WorldWideScience

Sample records for exergy based fluid

  1. Evaluation of Working Fluids for Organic Rankine Cycle Based on Exergy Analysis

    Science.gov (United States)

    Setiawan, D.; Subrata, I. D. M.; Purwanto, Y. A.; Tambunan, A. H.

    2018-05-01

    One of the crucial aspects to determine the performance of Organic Rankine Cycle (ORC) is the selection of appropriate working fluids. This paper describes the simulative performance of several organic fluid and water as working fluid of an ORC based on exergy analysis with a heat source from waste heat recovery. The simulation was conducted by using Engineering Equation Solver (EES). The effect of several parameters and thermodynamic properties of working fluid was analyzed, and part of them was used as variables for the simulation in order to determine their sensitivity to the exergy efficiency changes. The results of this study showed that water is not appropriate to be used as working fluid at temperature lower than 130 °C, because the expansion process falls in saturated area. It was also found that Benzene had the highest exergy efficiency, i.e. about 10.49%, among the dry type working fluid. The increasing turbine inlet temperature did not lead to the increase of exergy efficiency when using organic working fluids with critical temperature near heat source temperature. Meanwhile, exergy efficiency decreasing linearly with the increasing condenser inlet temperature. In addition, it was found that working fluid with high latent heat of vaporization and specific heat exert in high exergy efficiency.

  2. Selection of Optimum Working Fluid for Organic Rankine Cycles by Exergy and Exergy-Economic Analyses

    Directory of Open Access Journals (Sweden)

    Kamyar Darvish

    2015-11-01

    Full Text Available The thermodynamic performance of a regenerative organic Rankine cycle that utilizes low temperature heat sources to facilitate the selection of proper organic working fluids is simulated. Thermodynamic models are used to investigate thermodynamic parameters such as output power, and energy efficiency of the ORC (Organic Rankine Cycle. In addition, the cost rate of electricity is examined with exergo-economic analysis. Nine working fluids are considered as part of the investigation to assess which yields the highest output power and exergy efficiency, within system constraints. Exergy efficiency and cost rate of electricity are used as objective functions for system optimization, and each fluid is assessed in terms of the optimal operating condition. The degree of superheat and the pressure ratio are independent variables in the optimization. R134a and iso-butane are found to exhibit the highest energy and exergy efficiencies, while they have output powers in between the systems using other working fluids. For a source temperature was equal to 120 °C, the exergy efficiencies for the systems using R134a and iso-butane are observed to be 19.6% and 20.3%, respectively. The largest exergy destructions occur in the boiler and the expander. The electricity cost rates for the system vary from 0.08 USD/kWh to 0.12 USD/kWh, depending on the fuel input cost, for the system using R134a as a working fluid.

  3. Thermal performance of gas turbine power plant based on exergy analysis

    International Nuclear Information System (INIS)

    Ibrahim, Thamir K.; Basrawi, Firdaus; Awad, Omar I.; Abdullah, Ahmed N.; Najafi, G.; Mamat, Rizlman; Hagos, F.Y.

    2017-01-01

    Highlights: • Modelling theoretical framework for the energy and exergy analysis of the Gas turbine. • Investigated the effects of ambient temperature on the energy and exergy performance. • The maximum exergy loss occurs in the gas turbine components. - Abstract: This study is about energy and exergy analysis of gas turbine power plant. Energy analysis is more quantitatively while exergy analysis is about the same but with the addition of qualitatively. The lack quality of the thermodynamic process in the system leads to waste of potential energy, also known as exergy destruction which affects the efficiency of the power plant. By using the first and second law of thermodynamics, the model for the gas turbine power plant is built. Each component in the thermal system which is an air compressor, combustion chamber and gas turbine play roles in affecting the efficiency of the gas turbine power plant. The exergy flow rate for the compressor (AC), the combustion chamber (CC) and the gas turbine (GT) inlet and outlet are calculated based on the physical exergy and chemical exergy. The exergy destruction calculation based on the difference between the exergy flow in and exergy flow out of the component. The combustion chamber has the highest exergy destruction. The air compressor has 94.9% and 92% of exergy and energy efficiency respectively. The combustion chamber has 67.5% and 61.8% of exergy and energy efficiency respectively while gas turbine has 92% and 82% of exergy and energy efficiency respectively. For the overall efficiency, the plant has 32.4% and 34.3% exergy and energy efficiency respectively. To enhance the efficiency, the intake air temperature should be reduced, modify the combustion chamber to have the better air-fuel ratio and increase the capability of the gas turbine to receive high inlet temperature.

  4. Experimental investigation and exergy analysis of a triple fluid vapor absorption refrigerator

    International Nuclear Information System (INIS)

    Jemaa, Radhouane Ben; Mansouri, Rami; Boukholda, Ismail; Bellagi, Ahmed

    2016-01-01

    Highlights: • Experimental study on a commercial triple fluid vapor absorption refrigerator performed. • An Aspen-hysys model developed and validated with experimental measurements. • Exergy analysis of the unit performed and discussed. • Absorber identified as largest source of irreversibility, followed by solution heat exchanger. - Abstract: This paper presents an energy and exergy analyses of a triple fluid vapor absorption refrigerator working with ammonia as refrigerant, water as absorbent and hydrogen as auxiliary gas. The experimental setup is constituted of a commercial unit equipped with the appropriate metrology. The temperature at the inlet and outlet of every component of the machine, as well as the cabinet and ambient temperature are continuously measured and monitored. A simulation model of the machine is developed using the process simulator Aspen-Hysys. The thermodynamic analysis includes energy and exergy efficiency calculations, destroyed exergy evaluation and degradation of the coefficient of performance (COP) in each component of the refrigerator. The results indicate that the absorber exhibits the largest source of irreversibility followed by the solution heat exchanger. These two components alone are at the origin of 63% of the total degradation of COP.

  5. Ecological accounting based on extended exergy: a sustainability perspective.

    Science.gov (United States)

    Dai, Jing; Chen, Bin; Sciubba, Enrico

    2014-08-19

    The excessive energy consumption, environmental pollution, and ecological destruction problems have gradually become huge obstacles for the development of societal-economic-natural complex ecosystems. Regarding the national ecological-economic system, how to make explicit the resource accounting, diagnose the resource conversion, and measure the disturbance of environmental emissions to the systems are the fundamental basis of sustainable development and coordinated management. This paper presents an extended exergy (EE) accounting including the material exergy and exergy equivalent of externalities consideration in a systematic process from production to consumption, and China in 2010 is chosen as a case study to foster an in-depth understanding of the conflict between high-speed development and the available resources. The whole society is decomposed into seven sectors (i.e., Agriculture, Extraction, Conversion, Industry, Transportation, Tertiary, and Domestic sectors) according to their distinct characteristics. An adaptive EE accounting database, which incorporates traditional energy, renewable energy, mineral element, and other natural resources as well as resource-based secondary products, is constructed on the basis of the internal flows in the system. In addition, the environmental emission accounting has been adjusted to calculate the externalities-equivalent exergy. The results show that the EE value for the year 2010 in China was 1.80 × 10(14) MJ, which is greatly increased. Furthermore, an EE-based sustainability indices system has been established to provide an epitomized exploration for evaluating the performance of flows and storages with the system from a sustainability perspective. The value of the EE-based sustainability indicator was calculated to be 0.23, much lower than the critical value of 1, implying that China is still developing in the stages of high energy consumption and a low sustainability level.

  6. Performance analysis of ventilation systems with desiccant wheel cooling based on exergy destruction

    International Nuclear Information System (INIS)

    Tu, Rang; Liu, Xiao-Hua; Hwang, Yunho; Ma, Fei

    2016-01-01

    Highlights: • Ventilation systems with desiccant wheel were analyzed from exergy destruction. • Main performances influencing factors for ventilation systems are put forward. • Improved ventilation systems with lower exergy destruction are suggested. • Performances of heat pumps driven ventilation systems are greatly increased. - Abstract: This paper investigates the performances of ventilation systems with desiccant wheel cooling from the perspective of exergy destructions. Based on the inherent influencing factors for exergy destructions of heat and mass transfer and heat sources, provide guidelines for efficient system design. First, performances of a basic ventilation system are simulated, which is operated at high regeneration temperature and low coefficient of performance (COP). Then, exergy analysis of the basic ventilation system shows that exergy destructions mainly exist in the heat and mass transfer components and the heat source. The inherent influencing factors for the heat and mass transfer exergy destruction are heat and mass transfer capacities, which are related to over dehumidification of the desiccant wheel, and unmatched coefficients, which represent the uniformity of the temperature or humidity ratio differences fields for heat and mass transfer components. Based on these findings, two improved ventilation systems are suggested. For the first system, over dehumidification is avoided and unmatched coefficients for each component are reduced. With lower heat and mass transfer exergy destructions and lower regeneration temperature, COP and exergy efficiency of the first system are increased compared with the basic ventilation system. For the second system, a heat pump, which recovers heat from the process air to heat the regeneration air, is adopted to replace the electrical heater and cooling devices. The exergy destruction of the heat pump is considerably reduced as compared with heat source exergy destruction of the basic ventilation

  7. Environmental emissions by Chinese industry: Exergy-based unifying assessment

    International Nuclear Information System (INIS)

    Bo Zhang; Chen, G.Q.; Xia, X.H.; Li, S.C.; Chen, Z.M.; Xi Ji

    2012-01-01

    Based on chemical exergy as an objective measure for the chemical deviation between the emission and the environment, a unifying assessment is carried out for major environmental emissions covering COD, ammonia nitrogen, SO 2 , soot, dust, NO x and solid waste by Chinese industry over 1997–2006, with emphasis on the sectoral and regional levels in 2006. Of the total emission in exergy up to 274.1 PJ in 2006, 67.7% is estimated from waste gases, 29.9% from waste water and 2.4% from solid waste. Five of 40 sectors and 12 of 30 regions are responsible for 72.7% and 65.5% of the total emission, respectively. SO 2 is the leading emission type in 9 sectors and 25 regions, and COD in another 28 sectors and 5 regions. Some pollution-intensive sectors such as Production and Distribution of Electric Power and Heat Power and Manufacture of Paper and Paper Products, and western and inland regions such as Guangxi and Ningxia with high emission intensities are identified. By clustering and disjoint principal component analysis with intensities of emissions and fuel coal use as variables, three principal components are extracted, and four statistically significant clusters are pinpointed in the sectoral and regional analysis. Corresponding policy-making implications are addressed. - Highlights: ► A chemical exergy-based unifying assessment for industrial emissions is performed. ► The emissions at the sectoral/regional levels in 2006 are systematically revealed. ► The main principal components and clusters for emission intensities are pinpointed.

  8. A general exergy-based environmental impact index

    International Nuclear Information System (INIS)

    Diaz-Mendez, Sosimo E.; Rodriguez-Lelis, Jose Maria; Hernandez-Guerrero, Abel

    2011-01-01

    An ecosystem is a complex system in which biotic and abiotic factors interact and influence each other both directly and indirectly. Each of these factors has to comply with a specific function in the different processes that occur inside the ecosystem, whether transporting or transforming energy or both. When anthropogenic emissions are produced, part of the useful energy of the ecosystem is used to assimilate or absorb those emissions, and the energy spent, loses its function and becomes lost work in accordance with the Gouy-Stodola theorem. Thus, the work that an ecosystem can carry out varies as a function of the lost work produced by anthropogenic sources. The permanency or loss of the ecosystem depends on how many irreversibilities it can support. The second law of thermodynamics through a systematic use of the exergy and lost work is the basis of this paper where a general environmental impact index, based on exergy, is proposed. For the purpose of this work, the ecosystem is divided in subsystems--water, soil, atmosphere, organisms and society- -all of them inter-related. The ideal work variation can be obtained from each subsystem within the selected ecosystem, and a global index can be determined by adding the partial lost work of each subsystem. This global index is then used to determine the trend followed by the ecosystem from its pristine, original or environmental line base state. This environmental impact index applicability is presented for a simple combustion example

  9. Exergy-based comparison of two Greek industries

    DEFF Research Database (Denmark)

    Xydis, George; Koroneos, C.; Naniki, E.

    2011-01-01

    In this work, the potential of the increase in exergy and energy efficiency of the Greek construction and Food, Drink and Tobacco (FDT) industries has been examined using energy and exergy analysis methodology. These two industries play a vital role towards sustainable development of the country....... The continuous increase in energy use in these two industries during the years 1971–2000 shows that both remain steadily in an ascendant orbit. The aim was to analyse and compare the energy use and exergy consumption in the Greek construction and FDT industries to gain insights into each sector's efficiency...

  10. The role of an exergy-based building stock model for exploration of future decarbonisation scenarios and policy making

    International Nuclear Information System (INIS)

    García Kerdan, Iván; Raslan, Rokia; Ruyssevelt, Paul; Morillón Gálvez, David

    2017-01-01

    State-of-the-art research suggests that energy systems are best evaluated using exergy analysis, as exergy represents the real value of an energy source, demonstrating it to be the only rational basis for evaluation. After discovering the lack of thermodynamic integration into stock modelling, this paper presents the development of an exergy-based building stock model. The aim of this paper is twofold. Firstly, to investigate the impact of large-scale future energy retrofit scenarios in the English and Welsh (E&W) non-domestic sector, and secondly, to determine the potential of exergy analysis in improving sectoral efficiency and its potential implications on exergy-oriented policy making. The research explores seven different large-scale future retrofit scenarios that encompass typical, low-carbon, and low-exergy approaches. Modelling results show that by 2050, current regulations have the potential to reduce carbon emissions by up to 49.0±2.9% and increasing sector thermodynamic efficiency from 10.7% to 13.7%. On the other hand, a low-exergy oriented scenario based on renewable electricity and heat pumps is able to reduce carbon emissions by 88.2±2.4%, achieving a sectoral exergy efficiency of 19.8%. This modelling framework can provide energy policy makers with new insights on policy options based on exergy indicators and the assessment of their potential impact. - Highlights: • A bottom-up exergy-based model was developed to analyse the UK non-domestic sector. • Different low-carbon and low-exergy large-scale retrofit scenarios were assessed. • The UK non-domestic sector as a whole has an exergy efficiency of 10.7±4.06%. • Exergy-based retrofits could reduce sectoral carbon emissions by 88±2.4% for 2050. • Exergy oriented policies are required to obtain a sustainable building sector.

  11. Human Body Exergy Metabolism

    OpenAIRE

    Mady, Carlos Eduardo Keutenedjian

    2013-01-01

    The exergy analysis of the human body is a tool that can provide indicators of health and life quality. To perform the exergy balance it is necessary to calculate the metabolism on an exergy basis, or metabolic exergy, although there is not yet consensus in its calculation procedure. Hence, the aim of this work is to provide a general method to evaluate this physical quantity for human body based on indirect calorimetry data. To calculate the metabolism on an exergy basis it is necessary to d...

  12. Development of a correlation for parameter controlling using exergy efficiency optimization of an Al_2O_3/water nanofluid based flat-plate solar collector

    International Nuclear Information System (INIS)

    Shojaeizadeh, Ehsan; Veysi, Farzad

    2016-01-01

    Highlights: • Exergy efficiency optimization of a flat-plate collector with Al_2O_3 nanofluid is studied. • Solar radiation and ambient temperature are assumed to be uncontrollable. • Solar collector inlet temperature is influenced by the presence of reservoir tank. • A suitable exponential correlation is proposed for the optimized exergy efficiency. • This exponential correlation also is used for controlling independent parameters. - Abstract: The current study deals with the exergy efficiency optimization of an Al_2O_3/water nanofluid-based flat-plate solar collector according to a mathematical optimization (Sequential Quadratic Programming (SQP) method). This study takes into account exergy efficiency optimization when solar radiation and ambient temperature parameters are assumed to be uncontrollable and presented to a wide range of transient data of climatic conditions where these might take place during spring and summer seasons of Kermanshah (Iran), and perform two main cases as follows: (1) the fluid temperature at the inlet of solar collector, T_i, is independent of storage tank (open loop); (2) the fluid temperature at the inlet of solar collector, T_i, is influenced by the presence of storage tank (closed loop). In any conditions of each case studies (working fluid with and without nanoparticles), a suitable decreasing exponential correlation as function of T_a/G_t values (i.e. ambient temperature to solar radiation ratio) is developed for the optimized exergy efficiency and also well controlling independent parameters values (mass flow rate of fluid, nanoparticle volume concentration and collector inlet temperature). Also, it is concluded that each of optimized parameters and the optimum exergy efficiency is of a linear relation with each other.

  13. Sensitivity analysis of exergy destruction in a real combined cycle power plant based on advanced exergy method

    International Nuclear Information System (INIS)

    Boyaghchi, Fateme Ahmadi; Molaie, Hanieh

    2015-01-01

    Highlights: • The advanced exergy destruction components of a real CCPP are calculated. • The TIT and r c variation are investigated on exergy destruction parts of the cycle. • The TIT and r c growth increase the improvement potential in the most of components. • The TIT and r c growth decrease the unavoidable part in some components. - Abstract: The advanced exergy analysis extends engineering knowledge beyond the respective conventional methods by improving the design and operation of energy conversion systems. In advanced exergy analysis, the exergy destruction is splitting into endogenous/exogenous and avoidable/unavoidable parts. In this study, an advanced exergy analysis of a real combined cycle power plant (CCPP) with supplementary firing is done. The endogenous/exogenous irreversibilities of each component as well as their combination with avoidable/unavoidable irreversibilities are determined. A parametric study is presented discussing the sensitivity of various performance indicators to the turbine inlet temperature (TIT), and compressor pressure ratio (r c ). It is observed that the thermal and exergy efficiencies increase when TIT and r c rise. Results show that combustion chamber (CC) concentrates most of the exergy destruction (more than 62%), dominantly in unavoidable endogenous form which is decreased by 11.89% and 13.12% while the avoidable endogenous exergy destruction increase and is multiplied by the factors of 1.3 and 8.6 with increasing TIT and r c , respectively. In addition, TIT growth strongly increases the endogenous avoidable exergy destruction in high pressure superheater (HP.SUP), CC and low pressure evaporator (LP.EVAP). It, also, increases the exogenous avoidable exergy destruction of HP.SUP and low pressure steam turbine (LP.ST) and leads to the high decrement in the endogenous exergy destruction of the preheater (PRE) by about 98.8%. Furthermore, r c growth extremely rises the endogenous avoidable exergy destruction of gas

  14. The calculation of the chemical exergies of coal-based fuels by using the higher heating values

    International Nuclear Information System (INIS)

    Bilgen, Selcuk; Kaygusuz, Kamil

    2008-01-01

    This paper demonstrates the application of exergy to gain a better understanding of coal properties, especially chemical exergy and specific chemical exergy. In this study, a BASIC computer program was used to calculation of the chemical exergies of the coal-based fuels. Calculations showed that the chemical composition of the coal influences strongly the values of the chemical exergy. The exergy value of a coal is closely related to the H:C and O:C ratios. High proportions of hydrogen and/or oxygen, compared to carbon, generally reduce the exergy value of the coal. High contents of the moisture and/or the ash cause to low values of the chemical exergy. The aim of this paper is to calculate the chemical exergy of coals by using equations given in the literature and to detect and to evaluate quantitatively the effect of irreversible phenomena increased the thermodynamic imperfection of the processes. In this paper, the calculated exergy values of the fuels will be useful for energy experts studied in the coal mining area and coal-fired powerplants

  15. An exergy analysis on the performance of a counterflow wet cooling tower

    International Nuclear Information System (INIS)

    Muangnoi, Thirapong; Asvapoositkul, Wanchai; Wongwises, Somchai

    2007-01-01

    Cooling towers are used to extract waste heat from water to atmospheric air. An energy analysis is usually used to investigate the performance characteristics of cooling tower. However, the energy concept alone is insufficient to describe some important viewpoints on energy utilization. In this study, an exergy analysis is used to indicate exergy and exergy destruction of water and air flowing through the cooling tower. Mathematical model based on heat and mass transfer principle is developed to find the properties of water and air, which will be further used in exergy analysis. The model is validated against experimental data. It is noted from the results that the amount of exergy supplied by water is larger than that absorbed by air, because the system produces entropy. To depict the utilizable exergy between water and air, exergy of each working fluid along the tower are presented. The results show that water exergy decreases continuously from top to bottom. On the other hand, air exergy is expressed in terms of convective and evaporative heat transfer. Exergy of air via convective heat transfer initially loses at inlet and slightly recovers along the flow before leaving the tower. However, exergy of air via evaporative heat transfer is generally high and able to consume exergy supplied by water. Exergy destruction is defined as the difference between water exergy change and air exergy change. It reveals that the cooling processes due to thermodynamics irreversibility perform poorly at bottom and gradually improve along the height of the tower. The results show that the lowest exergy destruction is located at the top of the tower

  16. Advanced exergy-based analyses applied to a system including LNG regasification and electricity generation

    Energy Technology Data Exchange (ETDEWEB)

    Morosuk, Tatiana; Tsatsaronis, George; Boyano, Alicia; Gantiva, Camilo [Technische Univ. Berlin (Germany)

    2012-07-01

    Liquefied natural gas (LNG) will contribute more in the future than in the past to the overall energy supply in the world. The paper discusses the application of advanced exergy-based analyses to a recently developed LNG-based cogeneration system. These analyses include advanced exergetic, advanced exergoeconomic, and advanced exergoenvironmental analyses in which thermodynamic inefficiencies (exergy destruction), costs, and environmental impacts have been split into avoidable and unavoidable parts. With the aid of these analyses, the potentials for improving the thermodynamic efficiency and for reducing the overall cost and the overall environmental impact are revealed. The objectives of this paper are to demonstrate (a) the potential for generating electricity while regasifying LNG and (b) some of the capabilities associated with advanced exergy-based methods. The most important subsystems and components are identified, and suggestions for improving them are made. (orig.)

  17. Exergy analysis on throttle reduction efficiency based on real gas equations

    International Nuclear Information System (INIS)

    Luo, Yuxi; Wang, Xuanyin

    2010-01-01

    This paper proposes an approach to calculate the efficiency of throttling in which the exergy (available energy) is used to evaluate the energy conversion processes. In the exergy calculation for real gases, a difficult part of integration can be removed by judiciously advised thermodynamic paths; the compressibility factor is calculated by using Peng-Robinson (P-R) equation. It is found that the largest deviation between the exergies calculated by the real gas equation and ideal gas assumption is about 1%. Because the exergy is a function of the pressure and temperature, the Joule-Thomson coefficients are used to calculate the temperature changes of throttling, based on the compressibility factors of the Soave-Redlich-Kwong (S-R-K) and P-R equations, and the temperature decreases are compared with those calculated by empirical formula. The result shows that the heat exergy contributes very little in throttling. The simple equation of ideal gas is suggested to calculate the efficiency of throttling for air at atmospheric temperatures.

  18. Multi-objective exergy-based optimization of a polygeneration energy system using an evolutionary algorithm

    International Nuclear Information System (INIS)

    Ahmadi, Pouria; Rosen, Marc A.; Dincer, Ibrahim

    2012-01-01

    A comprehensive thermodynamic modeling and optimization is reported of a polygeneration energy system for the simultaneous production of heating, cooling, electricity and hot water from a common energy source. This polygeneration system is composed of four major parts: gas turbine (GT) cycle, Rankine cycle, absorption cooling cycle and domestic hot water heater. A multi-objective optimization method based on an evolutionary algorithm is applied to determine the best design parameters for the system. The two objective functions utilized in the analysis are the total cost rate of the system, which is the cost associated with fuel, component purchasing and environmental impact, and the system exergy efficiency. The total cost rate of the system is minimized while the cycle exergy efficiency is maximized by using an evolutionary algorithm. To provide a deeper insight, the Pareto frontier is shown for multi-objective optimization. In addition, a closed form equation for the relationship between exergy efficiency and total cost rate is derived. Finally, a sensitivity analysis is performed to assess the effects of several design parameters on the system total exergy destruction rate, CO 2 emission and exergy efficiency.

  19. Benefits of Exergy-Based Analysis for Aerospace Engineering Applications—Part I

    Directory of Open Access Journals (Sweden)

    John H. Doty

    2009-01-01

    Full Text Available This paper compares the analysis of systems from two different perspectives: an energy-based focus and an exergy-based focus. A complex system was simply modeled as interacting thermodynamic systems to illustrate the differences in analysis methodologies and results. The energy-based analysis had combinations of calculated states that are infeasible. On the other hand, the exergy-based analyses only allow feasible states. More importantly, the exergy-based analyses provide clearer insight to the combination of operating conditions for optimum system-level performance. The results strongly suggest changing the analysis/design paradigm used in aerospace engineering from energy-based to exergy-based. This methodology shift is even more critical in exploratory research and development where previous experience may not be available to provide guidance. Although the models used herein may appear simplistic, the message is very powerful and extensible to higher-fidelity models: the 1st Law is only a necessary condition for design, whereas the 1st and 2nd Laws provide the sufficiency condition.

  20. Energy and exergy analysis of a double effect absorption refrigeration system based on different heat sources

    International Nuclear Information System (INIS)

    Kaynakli, Omer; Saka, Kenan; Kaynakli, Faruk

    2015-01-01

    Highlights: • Energy and exergy analysis was performed on double effect series flow absorption refrigeration system. • The refrigeration system runs on various heat sources such as hot water, hot air and steam. • A comparative analysis was carried out on these heat sources in terms of exergy destruction and mass flow rate of heat source. • The effect of heat sources on the exergy destruction of high pressure generator was investigated. - Abstract: Absorption refrigeration systems are environmental friendly since they can utilize industrial waste heat and/or solar energy. In terms of heat source of the systems, researchers prefer one type heat source usually such as hot water or steam. Some studies can be free from environment. In this study, energy and exergy analysis is performed on a double effect series flow absorption refrigeration system with water/lithium bromide as working fluid pair. The refrigeration system runs on various heat sources such as hot water, hot air and steam via High Pressure Generator (HPG) because of hot water/steam and hot air are the most common available heat source for absorption applications but the first law of thermodynamics may not be sufficient analyze the absorption refrigeration system and to show the difference of utilize for different type heat source. On the other hand operation temperatures of the overall system and its components have a major effect on their performance and functionality. In this regard, a parametric study conducted here to investigate this effect on heat capacity and exergy destruction of the HPG, coefficient of performance (COP) of the system, and mass flow rate of heat sources. Also, a comparative analysis is carried out on several heat sources (e.g. hot water, hot air and steam) in terms of exergy destruction and mass flow rate of heat source. From the analyses it is observed that exergy destruction of the HPG increases at higher temperature of the heat sources, condenser and absorber, and lower

  1. Energy and exergy analysis of solar power tower plants

    International Nuclear Information System (INIS)

    Xu Chao; Wang Zhifeng; Li Xin; Sun Feihu

    2011-01-01

    Establishing the renewable electricity contribution from solar thermal power systems based on energy analysis alone cannot legitimately be complete unless the exergy concept becomes a part of that analysis. This paper presents a theoretical framework for the energy analysis and exergy analysis of the solar power tower system using molten salt as the heat transfer fluid. Both the energy losses and exergy losses in each component and in the overall system are evaluated to identify the causes and locations of the thermodynamic imperfection. Several design parameters including the direct normal irradiation (DNI), the concentration ratio, and the type of power cycle are also tested to evaluate their effects on the energy and exergy performance. The results show that the maximum exergy loss occurs in the receiver system, followed by the heliostat field system, although main energy loss occurs in the power cycle system. The energy and exergy efficiencies of the receiver and the overall system can be increased by increasing the DNI and the concentration ratio, but that increment in the efficiencies varies with the values of DNI and the concentration ratio. It is also found that the overall energy and exergy efficiencies of the solar tower system can be increased to some extent by integrating advanced power cycles including reheat Rankine cycles and supercritical Rankine cycles. - Highlights: →We presented a theoretical framework for the energy and exergy analysis of the solar tower system. →We tested the effects of several design parameters on the energy and exergy performance. →The maximum exergy loss occurs in the receiver system, followed by the heliostat field system. →Integrating advanced power cycles leads to increases in the overall energy and exergy efficiencies.

  2. Enhancement of exergy efficiency in combustion systems using flameless mode

    International Nuclear Information System (INIS)

    Hosseini, Seyed Ehsan; Wahid, Mazlan Abdul

    2014-01-01

    Highlights: • Exergy efficiency in flameless combustion mode is 13% more than conventional combustion. • The maximum exergy efficiency in flameless combustion mode is achieved when oxidizer contains 10% oxygen. • Exergy destruction of flameless combustion is maximized when CO 2 is used for dilution of oxidizer. - Abstract: An exergitic-based analysis of methane (CH 4 ) conventional and flameless combustion in a lab-scale furnace is performed to determine the rate of pollutant formation and the effective potential of a given amount of fuel in the various combustion modes. The effects of inlet air temperature on exergy efficiency and pollutant formation of conventional combustion in various equivalence ratios are analyzed. The rate of exergy destruction in different conditions of flameless combustion (various equivalence ratios, oxygen concentration in the oxidizer and the effects of diluent) are computed using three-dimensional (3D) computational fluid dynamic (CFD). Fuel consumption reduction and exergy efficiency augmentation are the main positive consequences of using preheated air temperature in conventional combustion, however pollutants especially NO x formation increases dramatically. Low and moderate temperature inside the chamber conducts the flameless combustion system to low level pollutant formation. Fuel consumption and exergy destruction reduce drastically in flameless mode in comparison with conventional combustion. Exergy efficiency of conventional and flameless mode is 75% and 88% respectively in stoichiometric combustion. When CO 2 is used for dilution of oxidizer, chemical exergy increases due to high CO 2 concentration in the combustion products and exergy efficiency reduces around 2% compared to dilution with nitrogen (N 2 ). Since the rate of irreversibilities in combustion systems is very high in combined heat and power (CHP) generation and other industries, application of flameless combustion could be effective in terms of pollutant

  3. Analysis of exergy loss of gasoline surrogate combustion process based on detailed chemical kinetics

    International Nuclear Information System (INIS)

    Sun, Hongjie; Yan, Feng; Yu, Hao; Su, W.H.

    2015-01-01

    Highlights: • We explored the exergy loss sources of gasoline engine like combustion process. • The model combined non-equilibrium thermodynamics with detailed chemical kinetics. • We explored effects of initial conditions on exergy loss of combustion process. • Exergy loss decreases 15% of fuel chemical exergy by design of initial conditions. • Correspondingly, the second law efficiency increases from 38.9% to 68.9%. - Abstract: Chemical reaction is the most important source of combustion irreversibility in premixed conditions, but details of the exergy loss mechanisms have not been explored yet. In this study numerical analysis based on non-equilibrium thermodynamics combined with detailed chemical kinetics is conducted to explore the exergy loss mechanism of gasoline engine like combustion process which is simplified as constant volume combustion. The fuel is represented by the common accepted gasoline surrogates which consist of four components: iso-octane (57%), n-heptane (16%), toluene (23%), and 2-pentene (4%). We find that overall exergy loss is mainly composed of three peaks along combustion generated from chemical reactions in three stages, the conversion from large fuel molecules into small molecules (as Stage 1), the H 2 O 2 loop-related reactions (as Stage 2), and the violent oxidation reactions of CO, H, and O (as Stage 3). The effects of individual combustion boundaries, including temperature, pressure, equivalence ratio, oxygen concentration, on combustion exergy loss have been widely investigated. The combined effects of combustion boundaries on the total loss of gasoline surrogates are also investigated. We find that in a gasoline engine with a compression ratio of 10, the total loss can be reduced from 31.3% to 24.3% using lean combustion. The total loss can be further reduced to 22.4% by introducing exhaust gas recirculation and boosting the inlet charge. If the compression ratio is increased to 17, the total loss can be decreased to

  4. Environmental and exergy benefit of nanofluid-based hybrid PV/T systems

    International Nuclear Information System (INIS)

    Hassani, Samir; Saidur, R.; Mekhilef, Saad; Taylor, Robert A.

    2016-01-01

    Highlights: • Environmental and ExPBT analysis of different PV/T configurations is presented. • The exergy payback time of nanofluid-based hybrid PV/T system is about 2 years. • Nanofluid-based hybrid PV/T system is a reliable solution for pollution prevention. • Nanofluid-based hybrid PV/T system is highly recommended at high solar concentration. - Abstract: Photovoltaic/thermal (PV/T) solar systems, which produce both electrical and thermal energy simultaneously, represent a method to achieve very high conversion rates of sunlight into useful energy. In recent years, nanofluids have been proposed as efficient coolants and optical filter for PV/T systems. Aim of this paper is to theoretically analyze the life cycle exergy of three different configurations of nanofluids-based PV/T hybrid systems, and compare their performance to a standard PV and PV/T system. Electrical and thermal performance of the analyzed solar collectors was investigated numerically. The life cycle exergy analysis revealed that the nanofluids-based PV/T system showed the best performance compared to a standard PV and PV/T systems. At the optimum value of solar concentration C, nanofluid-based PV/T configuration with optimized optical and thermal properties produces ∼1.3 MW h/m 2 of high-grade exergy annually with the lowest exergy payback time of 2 years, whereas these are ∼0.36, ∼0.79 MW h/m 2 and 3.48, 2.55 years for standard PV and PV/T systems, respectively. In addition, the nanofluids-based PV/T system can prevent the emissions of about 448 kg CO 2 eq m −2 yr −1 . Overall, it was found that the nanofluids-based PV/T with optimized optical and thermal properties has potential for further development in a high-concentration solar system.

  5. Pitfalls of Exergy Analysis

    Science.gov (United States)

    Vágner, Petr; Pavelka, Michal; Maršík, František

    2017-04-01

    The well-known Gouy-Stodola theorem states that a device produces maximum useful power when working reversibly, that is with no entropy production inside the device. This statement then leads to a method of thermodynamic optimization based on entropy production minimization. Exergy destruction (difference between exergy of fuel and exhausts) is also given by entropy production inside the device. Therefore, assessing efficiency of a device by exergy analysis is also based on the Gouy-Stodola theorem. However, assumptions that had led to the Gouy-Stodola theorem are not satisfied in several optimization scenarios, e.g. non-isothermal steady-state fuel cells, where both entropy production minimization and exergy analysis should be used with caution. We demonstrate, using non-equilibrium thermodynamics, a few cases where entropy production minimization and exergy analysis should not be applied.

  6. Extended exergy-based sustainability accounting of a household biogas project in rural China

    International Nuclear Information System (INIS)

    Yang, J.; Chen, B.

    2014-01-01

    Biogas has been earmarked as one of the leading renewable energy sources capable of mitigating environmental emissions in rural areas. Thus, developing an accounting technique is of particular importance in coping with increasing problems related to renewable agriculture and rural energy supply. In this study, extended exergy was generalised for the sustainability evaluation of biogas projects. Furthermore, a series of extended exergy-based indicators was presented as benchmarking from the perspectives of resources, economics and greenhouse gas (GHG) emissions. The sustainability of a “Three-in-One” biogas production system in southern China was thereby evaluated based on the proposed framework. The results show that economic costs concentrate in the construction phase. GHG emissions are mainly derived from bricks and cement, with proportions of 36.23% and 34.91%, respectively. The largest resource depletion occurs during the consumption of feedstock (87.06%) in the operation phase. Compared with other renewable energy conversion systems, the biogas project has a higher renewability (0.925) and economic return on investment ratio (6.82) and a lower GHG emission intensity (0.012). With the merit of bridging thermodynamics and externality, the extended exergy-based approach presented in this study may effectively appraise the energy and environmental performance of biogas projects. - Highlights: • Extended exergy is used to describe the sustainability level of biogas projects. • A set of extended exergy based sustainability indicator is established. • Biogas project has high renewability and greenhouse gas emission abatement potential. • Multiple utilization of biogas digestate is a promising way to improve sustainability

  7. Thermodynamic and economic evaluations of a geothermal district heating system using advanced exergy-based methods

    International Nuclear Information System (INIS)

    Tan, Mehmet; Keçebaş, Ali

    2014-01-01

    Highlights: • Evaluation of a GDHS using advanced exergy-based methods. • Comparison of the results of the conventional and advanced exergy-based methods. • The modified exergetic efficiency and exergoeconomic factor are found as 45% and 13%. • Improvement and total cost-savings potentials are found to be 3% and 14%. • All the pumps have the highest improvement potential and total cost-savings potential. - Abstract: In this paper, a geothermal district heating system (GDHS) is comparatively evaluated in terms of thermodynamic and economic aspects using advanced exergy-based methods to identify the potential for improvement, the interactions among system components, and the direction and potential for energy savings. The actual operational data are taken from the Sarayköy GDHS, Turkey. In the advanced exergetic and exergoeconomic analyses, the exergy destruction and the total operating cost within each component of the system are split into endogenous/exogenous and unavoidable/avoidable parts. The advantages of these analyses over conventional ones are demonstrated. The results indicate that the advanced exergy-based method is a more meaningful and effective tool than the conventional one for system performance evaluation. The exergetic efficiency and the exergoeconomic factor of the overall system for the Sarayköy GDHS were determined to be 43.72% and 5.25% according to the conventional tools and 45.06% and 12.98% according to the advanced tools. The improvement potential and the total cost-savings potential of the overall system were also determined to be 2.98% and 14.05%, respectively. All of the pumps have the highest improvement potential and total cost-savings potential because the pumps were selected to have high power during installation at the Sarayköy GDHS

  8. Exergy analysis

    DEFF Research Database (Denmark)

    Dovjak, M.; Simone, Angela; Kolarik, Jakub

    2011-01-01

    al. (1998). The effect of different levels of RH, Ta and effective clothing insulation on human body exergy balance chain, changes in human body exergy consumption rate (hbExCr) and predicted mean vote (PMV) index were analyzed. The results show that thermal comfort conditions do not always results....... Hot and dry and cold and dry conditions have similar hbExCr. The difference appears, if the whole human body exergy balance chain is taken into consideration. To maintain comfortable conditions it is important that exergy consumption and stored exergy are at optimal values with a rational combination...

  9. An exergy-based multi-objective optimisation model for energy retrofit strategies in non-domestic buildings

    International Nuclear Information System (INIS)

    García Kerdan, Iván; Raslan, Rokia; Ruyssevelt, Paul

    2016-01-01

    While the building sector has a significant thermodynamic improvement potential, exergy analysis has been shown to provide new insight for the optimisation of building energy systems. This paper presents an exergy-based multi-objective optimisation tool that aims to assess the impact of a diverse range of retrofit measures with a focus on non-domestic buildings. EnergyPlus was used as a dynamic calculation engine for first law analysis, while a Python add-on was developed to link dynamic exergy analysis and a Genetic Algorithm optimisation process with the aforementioned software. Two UK archetype case studies (an office and a primary school) were used to test the feasibility of the proposed framework. Different measures combinations based on retrofitting the envelope insulation levels and the application of different HVAC configurations were assessed. The objective functions in this study are annual energy use, occupants' thermal comfort, and total building exergy destructions. A large range of optimal solutions was achieved highlighting the framework capabilities. The model achieved improvements of 53% in annual energy use, 51% of exergy destructions and 66% of thermal comfort for the school building, and 50%, 33%, and 80% for the office building. This approach can be extended by using exergoeconomic optimisation. - Highlights: • Integration of dynamic exergy analysis into a retrofit-oriented simulation tool. • Two UK non-domestic building archetypes are used as case studies. • The model delivers non-dominated solutions based on energy, exergy and comfort. • Exergy destructions of ERMs are optimised using GA algorithms. • Strengths and limitations of the proposed exergy-based framework are discussed.

  10. Exergy, exergoeconomic and environmental analyses and evolutionary algorithm based multi-objective optimization of combined cycle power plants

    International Nuclear Information System (INIS)

    Ahmadi, Pouria; Dincer, Ibrahim; Rosen, Marc A.

    2011-01-01

    A comprehensive exergy, exergoeconomic and environmental impact analysis and optimization is reported of several combined cycle power plants (CCPPs). In the first part, thermodynamic analyses based on energy and exergy of the CCPPs are performed, and the effect of supplementary firing on the natural gas-fired CCPP is investigated. The latter step includes the effect of supplementary firing on the performance of bottoming cycle and CO 2 emissions, and utilizes the first and second laws of thermodynamics. In the second part, a multi-objective optimization is performed to determine the 'best' design parameters, accounting for exergetic, economic and environmental factors. The optimization considers three objective functions: CCPP exergy efficiency, total cost rate of the system products and CO 2 emissions of the overall plant. The environmental impact in terms of CO 2 emissions is integrated with the exergoeconomic objective function as a new objective function. The results of both exergy and exergoeconomic analyses show that the largest exergy destructions occur in the CCPP combustion chamber, and that increasing the gas turbine inlet temperature decreases the CCPP cost of exergy destruction. The optimization results demonstrates that CO 2 emissions are reduced by selecting the best components and using a low fuel injection rate into the combustion chamber. -- Highlights: → Comprehensive thermodynamic modeling of a combined cycle power plant. → Exergy, economic and environmental analyses of the system. → Investigation of the role of multiobjective exergoenvironmental optimization as a tool for more environmentally-benign design.

  11. Exergy based methods for economic and risk design optimization of energy systems: Application to a gas turbine

    International Nuclear Information System (INIS)

    Cassetti, G.; Rocco, M.V.; Colombo, E.

    2014-01-01

    Exergy based analyses are considered by the scientific community appropriate tools for the design and the performance evaluation and improvements of energy systems. Moreover, they are today recognized as proper instruments to assess economic, environmental and social externalities of energy systems. This paper presents the results of a study in which different exergy analysis methods are adopted to determine the optimal design configuration of a gas turbine operating in simple Joule Brayton cycle. Standard exergy and Thermoeconomic analyses are performed to identify the highest thermodynamic efficiency and minimum economic cost configurations of the system, while for the environmental analysis Authors propose an innovative method in which the exergy analysis is combined with a Risk Analysis. With this method the total risk associated to the system is used as objective function in the same way as monetary cost is for standard Thermoeconomic analysis. These three methods aims therefore to determine the optimal design configurations of the system with respect to their specific objective functions, respectively: exergy cost (J/J), monetary (exergoeconomic) cost (€/J) and risk (injured/J) of the product. Results lead to three different optimal design parameters for the system, according to the objective of each analysis procedure. - Highlights: • An original implementation of Thermoeconomic framework is proposed. • Standard Exergy and Thermoeconomic analysis are performed on a case study. • A new model using exergy as allocation criteria for Risk Analysis is performed. • Different optimal configurations are obtained and compared

  12. Exergy Based Performance Analysis of Double Flow Solar Air Heater with Corrugated Absorber

    OpenAIRE

    S. P. Sharma; Som Nath Saha

    2017-01-01

    This paper presents the performance, based on exergy analysis of double flow solar air heaters with corrugated and flat plate absorber. A mathematical model of double flow solar air heater based on energy balance equations has been presented and the results obtained have been compared with that of a conventional flat-plate solar air heater. The double flow corrugated absorber solar air heater performs thermally better than the flat plate double flow and conventional flat-plate solar air heate...

  13. Exergy analysis of a coal/biomass co-hydrogasification based chemical looping power generation system

    International Nuclear Information System (INIS)

    Yan, Linbo; Yue, Guangxi; He, Boshu

    2015-01-01

    Power generation from co-utilization of coal and biomass is very attractive since this technology can not only save the coal resource but make sufficient utilization of biomass. In addition, with this concept, net carbon discharge per unit electric power generation can also be sharply reduced. In this work, a coal/biomass co-hydrogasification based chemical looping power generation system is presented and analyzed with the assistance of Aspen Plus. The effects of different operating conditions including the biomass mass fraction, R_b, the hydrogen recycle ratio, R_h_r, the hydrogasification pressure, P_h_g, the iron to fuel mole ratio, R_i_f, the reducer temperature, T_r_e, the oxidizer temperature, T_o_x, and the fuel utilization factor, U_f of the SOFC (solid oxide fuel cell) on the system operation results including the energy efficiency, η_e, the total energy efficiency, η_t_e, the exergy efficiency, η_e_x, the total exergy efficiency, η_t_e_x and the carbon capture rate, η_c_c, are analyzed. The energy and exergy balances of the whole system are also calculated and the corresponding Sankey diagram and Grassmann diagram are drawn. Under the benchmark condition, exergy efficiencies of different units in the system are calculated. η_t_e, η_t_e_x and η_c_c of the system are also found to be 43.6%, 41.2% and 99.1%, respectively. - Highlights: • A coal/biomass co-hydrogasification based chemical looping power generation system is setup. • Sankey and Grassmann diagrams are presented based on the energy and exergy balance calculations. • Sensitivity analysis is done to understand the system operation characteristics. • Total energy and exergy efficiencies of this system can be 43.6% and 41.2%, respectively. • About 99.1% of the carbon contained in coal and biomass can be captured in this system.

  14. Engineering design and exergy analyses for combustion gas turbine based power generation system

    International Nuclear Information System (INIS)

    Sue, D.-C.; Chuang, C.-C.

    2004-01-01

    This paper presents the engineering design and theoretical exergetic analyses of the plant for combustion gas turbine based power generation systems. Exergy analysis is performed based on the first and second laws of thermodynamics for power generation systems. The results show the exergy analyses for a steam cycle system predict the plant efficiency more precisely. The plant efficiency for partial load operation is lower than full load operation. Increasing the pinch points will decrease the combined cycle plant efficiency. The engineering design is based on inlet air-cooling and natural gas preheating for increasing the net power output and efficiency. To evaluate the energy utilization, one combined cycle unit and one cogeneration system, consisting of gas turbine generators, heat recovery steam generators, one steam turbine generator with steam extracted for process have been analyzed. The analytical results are used for engineering design and component selection

  15. Comparison between reverse Brayton and Kapitza based LNG boil-off gas reliquefaction system using exergy analysis

    Science.gov (United States)

    Kochunni, Sarun Kumar; Chowdhury, Kanchan

    2017-02-01

    LNG boil-off gas (BOG) reliquefaction systems in LNG carrier ships uses refrigeration devices which are based on reverse Brayton, Claude, Kapitza (modified Claude) or Cascade cycles. Some of these refrigeration devices use nitrogen as the refrigerants and hence nitrogen storage vessels or nitrogen generators needs to be installed in LNG carrier ships which consume space and add weight to the carrier. In the present work, a new configuration based on Kapitza liquefaction cycle which uses BOG itself as working fluid is proposed and has been compared with Reverse Brayton Cycle (RBC) on sizes of heat exchangers and compressor operating parameters. Exergy analysis is done after simulating at steady state with Aspen Hysys 8.6® and the comparison between RBC and Kapitza may help designers to choose reliquefaction system with appropriate process parameters and sizes of equipment. With comparable exergetic efficiency as that of an RBC, a Kaptiza system needs only BOG compressor without any need of nitrogen gas.

  16. Biomass boiler energy conversion system analysis with the aid of exergy-based methods

    International Nuclear Information System (INIS)

    Li, Changchun; Gillum, Craig; Toupin, Kevin; Donaldson, Burl

    2015-01-01

    Highlights: • Conventional exergy analysis and advanced exergy analysis are performed. • The combustion process dominates the exergy destruction. • Increase excess air will decrease the overall boiler exergy efficiency. • Increase the SH temperatures will increase the overall boiler exergy efficiency. • The avoidable exergy destructions in the air heaters are very small. - Abstract: The objective of this paper is to establish a theoretical framework for the exergy analysis and advanced exergy analysis of a real biomass boiler. These analyses can be used for both the diagnosis and optimization of a biomass boiler as well as for the design of a new biomass boiler. Conventional exergy analysis is performed to recognize the source(s) of inefficiency and irreversibility and identify exergy destruction in different components of the biomass boiler. An advanced exergy analysis is performed to provide comprehensive information about the avoidable exergy destruction and real fuel-saving potential for each component, as well as the overall system. Sensitivity studies of several design parameters including the excess air, biomass moisture and steam parameters were evaluated. The results show that the maximum exergy destruction occurs in the combustion process, followed by the Water Walls (WW) & Radiant Superheater (RSH) and the Low Temperature Superheater (LTSH). The fuel-saving and exergy efficiency improvement strategies for different components are discussed in this paper

  17. Exergy assessment and optimization of a cogeneration system based on a solid oxide fuel cell integrated with a Stirling engine

    International Nuclear Information System (INIS)

    Hosseinpour, Javad; Sadeghi, Mohsen; Chitsaz, Ata; Ranjbar, Faramarz; Rosen, Marc A.

    2017-01-01

    Highlights: • A novel cogeneration system driven by a SOFC and Stirling engine is proposed. • Energy and exergy assessments are reported of a novel cogeneration system. • The energy efficiency of the combined system can be achieved 75.88%. • The highest exergy destruction occurs in the air heat exchanger. - Abstract: A cogeneration system based on a methane-fed solid oxide fuel cell (SOFC) integrated with a Stirling engine is analyzed from the viewpoints of energy and exergy. The effects on the system performance are investigated of varying four key system parameters: current density, SOFC inlet temperature, compression ratio and regenerator effectiveness. The energy efficiency of the combined system is found to be 76.32% which is about 24.61% more than that of a stand-alone SOFC plant under the same conditions. Considering exergy efficiency as the only objective function, it is found that, as the SOFC inlet temperature increases, the exergy efficiency of the cogeneration system rises to an optimal value of 56.44% and then decreases. The second law analysis also shows that the air heat exchanger has the greatest exergy destruction rate of all system components. The cooling water of the engine also can supply the heating needs for a small home.

  18. Modeling the exergy behavior of human body

    International Nuclear Information System (INIS)

    Keutenedjian Mady, Carlos Eduardo; Silva Ferreira, Maurício; Itizo Yanagihara, Jurandir; Hilário Nascimento Saldiva, Paulo; Oliveira Junior, Silvio de

    2012-01-01

    Exergy analysis is applied to assess the energy conversion processes that take place in the human body, aiming at developing indicators of health and performance based on the concepts of exergy destroyed rate and exergy efficiency. The thermal behavior of the human body is simulated by a model composed of 15 cylinders with elliptical cross section representing: head, neck, trunk, arms, forearms, hands, thighs, legs, and feet. For each, a combination of tissues is considered. The energy equation is solved for each cylinder, being possible to obtain transitory response from the body due to a variation in environmental conditions. With this model, it is possible to obtain heat and mass flow rates to the environment due to radiation, convection, evaporation and respiration. The exergy balances provide the exergy variation due to heat and mass exchange over the body, and the exergy variation over time for each compartments tissue and blood, the sum of which leads to the total variation of the body. Results indicate that exergy destroyed and exergy efficiency decrease over lifespan and the human body is more efficient and destroys less exergy in lower relative humidities and higher temperatures. -- Highlights: ► In this article it is indicated an overview of the human thermal model. ► It is performed the energy and exergy analysis of the human body. ► Exergy destruction and exergy efficiency decreases with lifespan. ► Exergy destruction and exergy efficiency are a function of environmental conditions.

  19. Exergy sustainability.

    Energy Technology Data Exchange (ETDEWEB)

    Robinett, Rush D. III (.; ); Wilson, David Gerald; Reed, Alfred W.

    2006-05-01

    Exergy is the elixir of life. Exergy is that portion of energy available to do work. Elixir is defined as a substance held capable of prolonging life indefinitely, which implies sustainability of life. In terms of mathematics and engineering, exergy sustainability is defined as the continuous compensation of irreversible entropy production in an open system with an impedance and capacity-matched persistent exergy source. Irreversible and nonequilibrium thermodynamic concepts are combined with self-organizing systems theories as well as nonlinear control and stability analyses to explain this definition. In particular, this paper provides a missing link in the analysis of self-organizing systems: a tie between irreversible thermodynamics and Hamiltonian systems. As a result of this work, the concept of ''on the edge of chaos'' is formulated as a set of necessary and sufficient conditions for stability and performance of sustainable systems. This interplay between exergy rate and irreversible entropy production rate can be described as Yin and Yang control: the dialectic synthesis of opposing power flows. In addition, exergy is shown to be a fundamental driver and necessary input for sustainable systems, since exergy input in the form of power is a single point of failure for self-organizing, adaptable systems.

  20. Optimal selection among different domestic energy consumption patterns based on energy and exergy analysis

    International Nuclear Information System (INIS)

    Lu, S.; Wu, J.Y.

    2010-01-01

    In China market, people have many choices for air conditioning of their apartments, including heat-pump systems or gas-fired boilers for heating and air conditioners for cooling. Domestic hot water is usually provided by domestic water heaters making use of electricity or natural gas, which are known for their great energy costs. These systems consume much energy and increase the total cost of required domestic energy. A novel system combining heat pump with water heater is proposed in this paper, and it is named domestic energy system. The system can realize the provision of space heating, cooling and domestic hot water throughout a year. Based on different types of air conditioners, space heating equipments and water heaters, domestic energy consumption patterns are concluded to be eight categories. This study describes and compares the eight domestic energy consumption patterns by economic analysis and prime energy analysis method. Results show that the domestic energy system can provide good economy and save energy significantly. Furthermore, exergy analysis method is employed to compare the exergy efficiencies of different energy consumption systems. The results show that the domestic energy system has the highest energy conversion efficiency and can make remarkable contribution to social energy saving.

  1. EXERGY OF TEXTILE MATERIALS

    Directory of Open Access Journals (Sweden)

    V. N. Romaniuk

    2015-01-01

    Full Text Available The article presents solution for the task of evaluating exergy of the substance in the flow for textile and woven fabrics based on thermodynamic analysis of the corresponding technical systems. The exergy method allows estimating the energy effectiveness for the most problematic heat-technological systems of substance transformation and thus outlining the ways for decreasing the electric-power component in the production prime cost. The actuality of the issue stems from the renowned scenario alteration on the world energy market and is aggravated by necessity of retaining and building up the export potential of the light industry as an important component of the republic national-economic complex. The exergy method has been here for quite a long time and saw the interest fading and appearing again with periodicity of the research-generations alternation. Cooling down of every new generation towards the specified method is explained mostly by unresolved problem of the exergy evaluation for diverse materials, which poses a problem in the course of analysis of the substance transformation systems. The specified problem as a general rule does not create obstacles for energyconversion systems. However, the situation with substance-transformation systems is by far more complicated primarily due to diversity of the materials and respectively of the specification peculiarities of such component of the substance exergy in the flow as chemical component. Abeyance of conclusion in finding the chemical component of the substance exergy does not allow performing thermodynamic valuation of the energy provision for the heat-technological process in full measure. Which complicates the matters of decision-making and finding a medium for reduction of their energy consumption. All stated above relates to the textile industry and in the first instance to the finishing production departments.The authors present the exergy-evaluation problem solution for the

  2. Exergy analysis of the LFC process

    International Nuclear Information System (INIS)

    Li, Qingsong; Lin, Yuankui

    2016-01-01

    Highlights: • Mengdong lignite was upgraded by liquids from coal (LFC) process at a laboratory-scale. • True boiling point distillation of tar was performed. • Basing on experimental data, the LFC process was simulated in Aspen Plus. • Amounts of exergy destruction and efficiencies of blocks were calculated. • Potential measures for improving the LFC process are suggested. - Abstract: Liquid from coal (LFC) is a pyrolysis technology for upgrading lignite. LFC is close to viability as a large-scale commercial technology and is strongly promoted by the Chinese government. This paper presents an exergy analysis of the LFC process producing semicoke and tar, simulated in Aspen Plus. The simulation included the drying unit, pyrolysis unit, tar recovery unit and combustion unit. To obtain the data required for the simulation, Mengdong lignite was upgraded using a laboratory-scale experimental facility based on LFC technology. True boiling point distillation of tar was performed. Based on thermodynamic data obtained from the simulation, chemical exergy and physical exergy were determined for process streams and exergy destruction was calculated. The exergy budget of the LFC process is presented as a Grassmann flow diagram. The overall exergy efficiency was 76.81%, with the combustion unit causing the highest exergy destruction. The study found that overall exergy efficiency can be increased by reducing moisture in lignite and making full use of physical exergy of pyrolysates. A feasible method for making full use of physical exergy of semicoke was suggested.

  3. Exergy analysis of single effect absorption refrigeration systems: The heat exchange aspect

    International Nuclear Information System (INIS)

    Joybari, Mahmood Mastani; Haghighat, Fariborz

    2016-01-01

    Highlights: • Exergy analysis of LiBr/H 2 O absorption systems with identical COP was carried out. • Exergy destruction rank: absorber followed by generator, condenser and evaporator. • Lower heat source and chilled water inlet temperature reduced exergy destruction. • Higher cooling water inlet temperature reduced exergy destruction. • Lower HTF mass flow rate increased exergy efficiency even for fixed system COP. - Abstract: The main limitation of conventional energy analysis for the thermal performance of energy systems is that this approach does not consider the quality of energy. On the other hand, exergy analysis not only provides information about the systems performance, but also it can specify the locations and magnitudes of losses. A number of studies investigated the effect of parameters such as the component temperature, and heat transfer fluid (HTF) temperature and mass flow rate on the exergetic performance of the same absorption refrigeration system; thus, reported different coefficient of performance (COP) values. However, in this study, the system COP was considered to remain constant during the investigation. This means comparing systems with different heat exchanger designs (based on HTF mass flow rate and temperature) having the same COP value. The effect of HTF mass flow rate and inlet temperature of the cooling water, chilled water and heat source on the outlet specific exergy and exergy destruction rate of each component was investigated. It was found that the lower HTF mass flow rate decreased exergy destruction of the corresponding component. Moreover, the lower temperature of heat source and chilled water inlet increased the system exergetic efficiency. That was also the case for the higher cooling water inlet temperature. Based on the analysis, since the absorber and condenser accounted for a large portion of the total exergy destruction, cooling tower modification with lower cooling water mass flow rate is recommended

  4. Exergy analysis of helium liquefaction systems based on modified Claude cycle with two-expanders

    Science.gov (United States)

    Thomas, Rijo Jacob; Ghosh, Parthasarathi; Chowdhury, Kanchan

    2011-06-01

    Large-scale helium liquefaction systems, being energy-intensive, demand judicious selection of process parameters. An effective tool for design and analysis of thermodynamic cycles for these systems is exergy analysis, which is used to study the behavior of a helium liquefaction system based on modified Claude cycle. Parametric evaluation using process simulator Aspen HYSYS® helps to identify the effects of cycle pressure ratio and expander flow fraction on the exergetic efficiency of the liquefaction cycle. The study computes the distribution of losses at different refrigeration stages of the cycle and helps in selecting optimum cycle pressures, operating temperature levels of expanders and mass flow rates through them. Results from the analysis may help evolving guidelines for designing appropriate thermodynamic cycles for practical helium liquefaction systems.

  5. Energy and Exergy Based Optimization of Licl-Water Absorption Cooling System

    Directory of Open Access Journals (Sweden)

    Bhargav Pandya

    2017-06-01

    Full Text Available This study presents thermodynamic analysis and optimization of single effect LiCl-H2O absorption cooling system. Thermodynamic models are employed in engineering equation solver to compute the optimum performance parameters. In this study, cut off temperature to operate system has been obtained at various operating temperatures. Analysis depicts that on 3.59 % rise in evaporator temperature, the required cut-off temperature decreased by 12.51%. By realistic comparison between thermodynamic first and second law analysis, optimum generator temperature relative to energy and exergy based prospective has been evaluated. It is found that optimum generator temperature is strong function of evaporator and condenser temperature. Thus, it is feasible to find out optimum generator temperature for various combinations of evaporator and condenser temperatures. Contour plots of optimum generator temperature for several combinations of condenser and absorber temperatures have been also depicted.

  6. Exergy efficiency analysis of ORC (Organic Rankine Cycle) and ORC-based combined cycles driven by low-temperature waste heat

    International Nuclear Information System (INIS)

    Sun, Wenqiang; Yue, Xiaoyu; Wang, Yanhui

    2017-01-01

    Highlights: • ORC-ARC and ORC-ERC driven by low-temperature waste heat are investigated. • Thermodynamic models of basic ORC, ORC-ARC, and ORC-ERC are developed. • Exergy efficiencies of ORC, ORC-ARC, and ORC-ERC are parametrically simulated. • Suitable application conditions of ORC-ARC and ORC-ERC are reported. - Abstract: There is large amount of waste heat resources in industrial processes. However, most low-temperature waste heat is directly discharged into the environment. With the advantages of being energy-efficient, enabling investment-savings and being environmentally friendly, the Organic Rankine Cycle (ORC) plays an important role in recycling energy from low-temperature waste heat. In this study, the ORC system driven by industrial low-temperature waste heat was analyzed and optimized. The impacts of the operational parameters, including evaporation temperature, condensation temperature, and degree of superheat, on the thermodynamic performances of ORC system were conducted, with R113 used as the working fluid. In addition, the ORC-based cycles, combined with the Absorption Refrigeration Cycle (ARC) and the Ejector Refrigeration Cycle (ERC), were investigated to recover waste heat from low-temperature flue gas. The uncoupled ORC-ARC and ORC-ERC systems can generate both power and cooling for external uses. The exergy efficiency of both systems decreases with the increase of the evaporation temperature of the ORC. The net power output, the refrigerating capacity and the resultant exergy efficiency of the uncoupled ORC-ARC are all higher than those of the ORC-ERC for the evaporation temperature of the basic ORC >153 °C, in the investigated application. Finally, suitable application conditions over other temperature ranges are also given.

  7. Exergy in School?

    Directory of Open Access Journals (Sweden)

    Tomaž Kranjc

    2017-04-01

    Information Technologies (UPR FAMNIT of the University of Primorska. Based on interviews and questionnaires given to two groups of students — an experimental and a control group — in the beginning and the end of the semester, we investigated the influence (and possible advantages of the introduction of the concept of exergy and the second-law ficiency. In the presentation, we show a few examples that were treated with the experimental group in order to motivate the students and to make them familiar with the concept of exergy: the “energy losses” of a car engine and an analysis of improvements still allowed by nature; exergy loss associated with heat conduction; a simple exergy analysis of a heating house system (considering energy and exergy fluxes. We list some of the problems encountered by the students and the most common misconceptions as could be identified from the tests, questionnaires and interviews. An additional goal of the investigation is to test a longer-term knowledge of students. From our research it would appear that exergy and the second-law efficiency are useful concepts which make it possible for students to get a better grasp of the material and to not only obtain a clearer understanding and knowledge of standard topics like heat engines, but also a broader view and insight into the meaning of energy and both the first and the second law, and their interrelation.

  8. Comparison based on energy and exergy analyses of the potential cogeneration efficiencies for fuel cells and other electricity generation devices

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, M A [Ryerson Polytechnical Inst., Toronto, (CA). Dept. of Mechanical Engineering

    1990-01-01

    Comparisons of the potential cogeneration efficiencies are made, based on energy and exergy analyses, for several devices for electricity generation. The investigation considers several types of fuel cell system (Phosphoric Acid, Alkaline, Solid Polymer Electrolyte, Molten Carbonate and Solid Oxide), and several fossil-fuel and nuclear cogeneration systems based on steam power plants. In the analysis, each system is modelled as a device for which fuel and air enter, and electrical- and thermal-energy products and material and thermal-energy wastes exit. The results for all systems considered indicate that exergy analyses should be used when analysing the cogeneration potential of systems for electricity generation, because they weigh the usefulnesses of heat and electricity on equivalent bases. Energy analyses tend to present overly optimistic views of performance. These findings are particularly significant when large fractions of the heat output from a system are utilized for cogeneration. (author).

  9. Energy, Exergy and Advanced Exergy Analysis of a Milk Processing Factory

    DEFF Research Database (Denmark)

    Bühler, Fabian; Nguyen, Tuong-Van; Jensen, Jonas Kjær

    2016-01-01

    integration, an exergy analysis pinpoints the locations, causes and magnitudes of thermodynamic losses. The advanced exergy analysis further identifies the real potential for thermodynamic improvements of the system by splitting exergy destruction into its avoidable and unavoidable parts, which are related......, cream and milk powder. The results show the optimisation potential based on 1st and 2nd law analyses. An evaluation and comparison of the applicability of exergy methods, including advanced exergy methods, to the dairy industry is made. The comparison includes typical energy mappings conducted onsite......, and discusses the benefits and challenges of applying advanced thermodynamic methods to industrial processes....

  10. Exergy-based assessment for waste gas emissions from Chinese transportation

    International Nuclear Information System (INIS)

    Ji Xi; Chen, G.Q.; Chen, B.; Jiang, M.M.

    2009-01-01

    As an effective measure for environmental impact associated with the waste emissions, exergy is used to unify the assessment of the waste gases of CO, NO x , and SO 2 emitted from fossil fuel consumption by the transportation system in China. An index of emission exergy intensity defined as the ratio of the total chemical exergy of the emissions and the total converted turnover of the transportation is proposed to quantify the environmental impact per unit of traffic service. Time series analyses are presented for the emission exergy and emission exergy intensity of the whole Chinese transportation as well as for its four sectors of highways, railways, waterways and civil aviation from 1978 to 2004. For the increasing emission exergy with CO taking the largest share, the highways sector was the major contributor, while the railways sector initially standing as the second main contributor developed into the least after 1995. The temporal and structural variations of the emissions are illustrated against the transition of the transportation system in a socio-economic perspective, with emphasis on policy-making implications.

  11. Exergy analysis of HTGR-GT

    International Nuclear Information System (INIS)

    Cao Jianhua; Wang Jie; Yang Xiaoyong; Yu Suyuan

    2005-01-01

    The High Temperature Gas-cooled Reactor (HTGR) coupled with gas turbine for high efficiency in electricity production is supposed to be one of the candidates for the future nuclear power plants. The HTGR gas turbine cycle is theoretically based on the Brayton cycle with recuperated, intercooled and precooled sub-processes. In this paper, an exergy analysis of the Brayton Cycle on HTGR is presented. The analyses were done for four typical reactor outlet temperatures and the exergy loss distribution and exergy loss ratio of each sub-process was quantified. The results show that more than a half of the exergy loss takes place in the reactor, while the low pressure compressor (LPC), the high pressure compressor (HPC) and the intercooler denoted by compress system together, play a much small role in the contribution of exergy losses. With the rise of the reactor outlet temperature, both the exergy loss and exergy loss ratio of the reactor can be greatly cut down, so is the total exergy loss of the cycle; while the exergy loss ratios of the recuperator and precooler have a small rise. The total exergy efficiency of the cycle is quite high (50% more or less). (authors)

  12. Exergy accounting - the energy that matters

    Energy Technology Data Exchange (ETDEWEB)

    Fachina, V. [Petroleo do Brasil S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil)], E-mail: vicentefachina@petrobras.com.br

    2009-07-01

    The exergy concept is introduced by utilizing a general framework on which are based the model equations. An exergy analysis is performed on a case study: a control volume for a power module is created by comprising gas turbine, reduction gearbox, AC generator, exhaustion ducts and heat regenerator. The implementation of the equations is carried out by collecting test data of the equipment data sheets from the respective vendors. By utilizing an exergy map, one proposes both mitigating and contingent countermeasures for maximizing the exergy efficiency. An exergy accounting is introduced by showing how the exergy concept might eventually be brought up to the traditional money accounting. At last, one devises a unified approach for efficiency metrics in order to bridge the gaps between the physical and the economical realms. (author)

  13. Exergy analysis of micro-organic Rankine power cycles for a small scale solar driven reverse osmosis desalination system

    International Nuclear Information System (INIS)

    Tchanche, B.F.; Lambrinos, Gr.; Frangoudakis, A.; Papadakis, G.

    2010-01-01

    Exergy analysis of micro-organic Rankine heat engines is performed to identify the most suitable engine for driving a small scale reverse osmosis desalination system. Three modified engines derived from simple Rankine engine using regeneration (incorporation of regenerator or feedliquid heaters) are analyzed through a novel approach, called exergy-topological method based on the combination of exergy flow graphs, exergy loss graphs, and thermoeconomic graphs. For the investigations, three working fluids are considered: R134a, R245fa and R600. The incorporated devices produce different results with different fluids. Exergy destruction throughout the systems operating with R134a was quantified and illustrated using exergy diagrams. The sites with greater exergy destruction include turbine, evaporator and feedliquid heaters. The most critical components include evaporator, turbine and mixing units. A regenerative heat exchanger has positive effects only when the engine operates with dry fluids; feedliquid heaters improve the degree of thermodynamic perfection of the system but lead to loss in exergetic efficiency. Although, different modifications produce better energy conversion and less exergy destroyed, the improvements are not significant enough and subsequent modifications of the simple Rankine engine cannot be considered as economically profitable for heat source temperature below 100 °C. As illustration, a regenerator increases the system's energy efficiency by 7%, the degree of thermodynamic perfection by 3.5% while the exergetic efficiency is unchanged in comparison with the simple Rankine cycle, with R600 as working fluid. The impacts of heat source temperature and pinch point temperature difference on engine's performance are also examined. Finally, results demonstrate that energy analysis combined with the mathematical graph theory is a powerful tool in performance assessments of Rankine based power systems and permits meaningful comparison of different

  14. Energy and exergy analysis of a closed Brayton cycle-based combined cycle for solar power tower plants

    International Nuclear Information System (INIS)

    Zare, V.; Hasanzadeh, M.

    2016-01-01

    Highlights: • A novel combined cycle is proposed for solar power tower plants. • The effects of solar subsystem and power cycle parameters are examined. • The proposed combined cycle yields exergy efficiencies of higher than 70%. • For the overall power plant exergy efficiencies of higher than 30% is achievable. - Abstract: Concentrating Solar Power (CSP) technology offers an interesting potential for future power generation and research on CSP systems of all types, particularly those with central receiver system (CRS) has been attracting a lot of attention recently. Today, these power plants cannot compete with the conventional power generation systems in terms of Levelized Cost of Electricity (LCOE) and if a competitive LCOE is to be reached, employing an efficient thermodynamic power cycle is deemed essential. In the present work, a novel combined cycle is proposed for power generation from solar power towers. The proposed system consists of a closed Brayton cycle, which uses helium as the working fluid, and two organic Rankine cycles which are employed to recover the waste heat of the Brayton cycle. The system is thermodynamically assessed from both the first and second law viewpoints. A parametric study is conducted to examine the effects of key operating parameters (including solar subsystem and power cycle parameters) on the overall power plant performance. The results indicate that exergy efficiencies of higher than 30% are achieved for the overall power plant. Also, according to the results, the power cycle proposed in this work has a better performance than the other investigated Rankine and supercritical CO_2 systems operating under similar conditions, for these types of solar power plants.

  15. Comparison between regenerative organic Rankine cycle (RORC) and basic organic Rankine cycle (BORC) based on thermoeconomic multi-objective optimization considering exergy efficiency and levelized energy cost (LEC)

    International Nuclear Information System (INIS)

    Feng, Yongqiang; Zhang, Yaning; Li, Bingxi; Yang, Jinfu; Shi, Yang

    2015-01-01

    Highlights: • The thermoeconomic comparison of regenerative RORC and BORC is investigated. • The Pareto frontier solution with bi-objective compares with the corresponding single-objective solutions. • The three-objective optimization of the RORC and BORC is studied. • The RORC owns 8.1% higher exergy efficiency and 21.1% more LEC than the BORC under the Pareto-optimal solution. - Abstract: Based on the thermoeconomic multi-objective optimization by using non-dominated sorting genetic algorithm (NSGA-II), considering both thermodynamic performance and economic factors, the thermoeconomic comparison of regenerative organic Rankine cycles (RORC) and basic organic Rankine cycles (BORC) are investigated. The effects of five key parameters including evaporator outlet temperature, condenser temperature, degree of superheat, pinch point temperature difference and degree of supercooling on the exergy efficiency and levelized energy cost (LEC) are examined. Meanwhile, the Pareto frontier solution with bi-objective for maximizing exergy efficiency and minimizing LEC is obtained and compared with the corresponding single-objective solutions. Research demonstrates that there is a significant negative correlation between thermodynamic performance and economic factors. And the optimum exergy efficiency and LEC for the Pareto-optimal solution of the RORC are 55.97% and 0.142 $/kW h, respectively, which are 8.1% higher exergy efficiency and 21.1% more LEC than that of the BORC under considered condition. Highest exergy and thermal efficiencies are accompanied with lowest net power output and worst economic performance. Furthermore, taking the net power output into account, detailed investigation on the three-objective optimization for maximizing exergy efficiency, maximizing net power output and minimizing LEC is discussed

  16. An innovative application of extended exergy analysis into an industrial park.

    Science.gov (United States)

    Fan, Yupeng; Qiao, Qi; Fang, Lin

    2017-04-01

    Exergy is a thermodynamic term used to account all possible useful work theoretically throughout one process when it is brought into equilibrium with its environment. It however cannot directly incorporate non-physical flows, which can be accounted by extensions of the exergy consumption method. Extended exergy, which builds a bridge between thermal and anthropic dimensions, can both measure resource consumption and economic system. In this study, we applied extended exergy analysis to analyze an industrial park, including material consumption, social investment, and environmental influence. The total extended exergy consumption in the study park amounts to 2.52 EJ. The material-based exergy occupies the largest exergy consumption, followed by capital exergy, environmental remediation exergy, and labor exergy in decreasing order. The exergy capacity was proposed to depict the conversion ability from exergy consumption into economic benefits. In the study area, electronic information industry has the largest exergy capacity with a value of 70 RMB/GJ, indicating a high conversion power from exergy to money. New energy vehicles and parts manufacturing occupies bottom rung in terms of exergy capacity. From the view of material consumption, other industry consumed a lot more exergy compared to electronic information industry; for the environmental remediation, other industry has the lowest exergy capacity, indicating it discharged more pollutants than other clusters to output the same amount of money. Therefore, other industry needs to be urgently transformed and upgraded. The study could help to optimize industrial structure and environmental management in industrial parks.

  17. Exergy performance of human body under physical activities

    International Nuclear Information System (INIS)

    Mady, Carlos Eduardo Keutenedjian; Albuquerque, Cyro; Fernandes, Tiago Lazzaretti; Hernandez, Arnaldo José; Saldiva, Paulo Hilário Nascimento; Yanagihara, Jurandir Itizo; Oliveira, Silvio de

    2013-01-01

    The aim of this work is to apply performance indicators for individuals under physical activity based on the concepts of exergy destroyed and exergy efficiency. The cardiopulmonary exercise test is one of the most used tests to assess the functional capacity of individuals with varying degrees of physical training. To perform the exergy analysis during the test, it is necessary to calculate heat and mass flow rates, associated with radiation, convection, vaporization and respiration, determined from the measurements and some relations found in the literature. The energy balance allowed the determination of the internal temperature over time and the exergy variation of the body along the experiment. Eventually, it was possible to calculate the destroyed exergy and the exergy efficiency from the exergy analysis. The exergy rates and flow rates are dependent of the exercise level and the body metabolism. The results show that the relation between the destroyed exergy and the metabolism is almost constant during the test, furthermore its value has a great dependence of the subject age. From the exergy analysis it was possible to divide the subjects according to their training level, for the same destroyed exergy, subjects with higher lactate threshold can perform more work. - Highlights: • Exergy analysis was applied to the human body under physical activities. • Concept of maximum available work from ATP hydrolysis was compared with exergy analysis results. • For the same destroyed exergy, subjects with higher lactate threshold can perform more work. • Runners during physical activities tend to a state of minimum destroyed exergy and maximum exergy efficiency

  18. Performance of Loaded Thermal Storage Unit with a Commercial Phase Change Materials based on Energy and Exergy Analysis

    Directory of Open Access Journals (Sweden)

    Abdullah Nasrallh Olimat

    2017-11-01

    Article History: Received July 6th 2017; Received in revised form September 15th 2017; Accepted 25th Sept 2017; Available online How to Cite This Article: Olimat, A.N., Awad, A.S., Al-Gathain, F.M., and Shaban, N.A.. (2017 Performance of Loaded Thermal Storage Unit With A Commercial Phase Change Materials Based on Energy and Exergy Analysis. International Journal of Renewable Energy Develeopment, 6(3,283-290. https://doi.org/10.14710/ijred.6.3.283-290

  19. Exergy-based sustainability analysis of a low power, high frequency piezo-based ultrasound reactor for rapid biodiesel production

    International Nuclear Information System (INIS)

    Aghbashlo, Mortaza; Tabatabaei, Meisam; Hosseinpour, Soleiman; Khounani, Zahra; Hosseini, Seyed Sina

    2017-01-01

    Highlights: • Piezoultrasonic-assisted biodiesel production was exergetically analyzed. • Alcohol content, sonication time, and temperature affected exergetic parameters. • 6:1 methanol/oil, 10 min sonication, and 60 °C temperature were the best conditions. • The exergetic sustainability index at the favorable conditions was found to be 11. - Abstract: In this work a thermodynamic model was developed to attain enhanced process comprehension of waste cooking oil (WCO) transesterification process in a low power, high frequency piezo-based ultrasound reactor. The reactor performance was assessed using the exergy concept to distinguish the effects of various operational variables, i.e., methanol to oil molar ratio (4:1–8:1), ultrasonic irradiation time (6–10 min), and temperature (40–60 °C) on the efficiency and sustainability factors. The exergetic efficiency of the developed reactor was found to be ranging from 98% to 99% and from 9% to 91% using the universal and functional definitions, respectively. The maximum functional exergetic efficiency as a decision making parameter, was found at 91% for methanol to oil molar ratio of 6:1, ultrasonic irradiation time of 10 min, and temperature of 60 °C. The exergetic sustainability index of the transesterification process at the selected conditions was determined at about 11. Under these conditions, the reactor efficiently converted triglycerides to methyl esters with an acceptable conversion efficiency of 97%, satisfying the ASTM standard. Overall, the outcomes of the current survey manifested that exergy analysis can be a preferred basis for decision making on the efficiency and sustainability of various biodiesel synthesizing systems.

  20. Nonlinear Slewing Spacecraft Control Based on Exergy, Power Flow, and Static and Dynamic Stability

    Science.gov (United States)

    Robinett, Rush D.; Wilson, David G.

    2009-10-01

    This paper presents a new nonlinear control methodology for slewing spacecraft, which provides both necessary and sufficient conditions for stability by identifying the stability boundaries, rigid body modes, and limit cycles. Conservative Hamiltonian system concepts, which are equivalent to static stability of airplanes, are used to find and deal with the static stability boundaries: rigid body modes. The application of exergy and entropy thermodynamic concepts to the work-rate principle provides a natural partitioning through the second law of thermodynamics of power flows into exergy generator, dissipator, and storage for Hamiltonian systems that is employed to find the dynamic stability boundaries: limit cycles. This partitioning process enables the control system designer to directly evaluate and enhance the stability and performance of the system by balancing the power flowing into versus the power dissipated within the system subject to the Hamiltonian surface (power storage). Relationships are developed between exergy, power flow, static and dynamic stability, and Lyapunov analysis. The methodology is demonstrated with two illustrative examples: (1) a nonlinear oscillator with sinusoidal damping and (2) a multi-input-multi-output three-axis slewing spacecraft that employs proportional-integral-derivative tracking control with numerical simulation results.

  1. Exergy and energy analyses of two different types of PCM based thermal management systems for space air conditioning applications

    International Nuclear Information System (INIS)

    Tyagi, V.V.; Pandey, A.K.; Buddhi, D.; Tyagi, S.K.

    2013-01-01

    Highlights: ► Calcium chloride hexahydrate (CaCl 2 ⋅6H 2 O) as a PCM was used in this study. ► Two different capsulated system (HDPE based panel and balls) were designed. ► The results of CaCl 2 ⋅6H 2 O are very attractive for space air conditioning. ► Energy and exergy analyses for space cooling applications. - Abstract: This communication presents the experimental study of PCM based thermal management systems for space heating and cooling applications using energy and exergy analysis. Two different types of based thermal management system (TMS-I and TMS-II) using calcium chloride hexahydrate as the heat carrier has been designed, fabricated and studied for space heating and cooling applications at a typical climatic zone in India. In the first experimental arrangement the charging of PCM has been carried out with air conditioning system while discharging has been carried out using electric heater for both the thermal management systems. While in the second arrangement the charging of PCM has been carried out by solar energy and the discharging has been carried out by circulating the cooler ambient air during the night time. In the first experiment, TMS-I is found to be more effective than that of TMS-II while it was found to be reverse in the case of second experiment for both the charging and discharging processes not only for energetic but also for the exergetic performances

  2. Exergy-based method for analyzing the composition of the electricity cost generated in gas-fired combined cycle plants

    Energy Technology Data Exchange (ETDEWEB)

    Sarraf Borelli, Samuel Jose [Promon Engenharia Ltda., Av. Presidente Juscelino Kubitschek, 1830, Itaim, CEP:04543-900 Sao Paulo/SP (Brazil)], E-mail: sborelli@terra.com.br; Oliveira Junior, Silvio de [Environmental and Thermal Engineering Laboratory, Polytechnic School, University of Sao Paulo, Av. Prof. Luciano Gualberto, 1289, Cidade Universitaria, CEP:05508-900 Sao Paulo/SP (Brazil)], E-mail: silvio.oliveira@poli.usp.br

    2008-02-15

    The proposed method to analyze the composition of the cost of electricity is based on the energy conversion processes and the destruction of the exergy through the several thermodynamic processes that comprise a combined cycle power plant. The method uses thermoeconomics to evaluate and allocate the cost of exergy throughout the processes, considering costs related to inputs and investment in equipment. Although the concept may be applied to any combined cycle or cogeneration plant, this work develops only the mathematical modeling for three-pressure heat recovery steam generator (HRSG) configurations and total condensation of the produced steam. It is possible to study any nx1 plant configuration (n sets of gas turbine and HRSGs associated to one steam turbine generator and condenser) with the developed model, assuming that every train operates identically and in steady state. The presented model was conceived from a complex configuration of a real power plant, over which variations may be applied in order to adapt it to a defined configuration under study [Borelli SJS. Method for the analysis of the composition of electricity costs in combined cycle thermoelectric power plants. Master in Energy Dissertation, Interdisciplinary Program of Energy, Institute of Eletro-technical and Energy, University of Sao Paulo, Sao Paulo, Brazil, 2005 (in Portuguese)]. The variations and adaptations include, for instance, use of reheat, supplementary firing and partial load operation. It is also possible to undertake sensitivity analysis on geometrical equipment parameters.

  3. Exergy-based method for analyzing the composition of the electricity cost generated in gas-fired combined cycle plants

    Energy Technology Data Exchange (ETDEWEB)

    Borelli, Samuel Jose Sarraf [Promon Engenharia Ltda., Av. Presidente Juscelino Kubitschek, 1830, Itaim, CEP:04543-900 Sao Paulo/SP (Brazil); De Oliveira Junior, Silvio [Environmental and Thermal Engineering Laboratory, Polytechnic School, University of Sao Paulo, Av. Prof. Luciano Gualberto, 1289, Cidade Universitaria, CEP:05508-900 Sao Paulo/SP (Brazil)

    2008-02-15

    The proposed method to analyze the composition of the cost of electricity is based on the energy conversion processes and the destruction of the exergy through the several thermodynamic processes that comprise a combined cycle power plant. The method uses thermoeconomics to evaluate and allocate the cost of exergy throughout the processes, considering costs related to inputs and investment in equipment. Although the concept may be applied to any combined cycle or cogeneration plant, this work develops only the mathematical modeling for three-pressure heat recovery steam generator (HRSG) configurations and total condensation of the produced steam. It is possible to study any n x 1 plant configuration (n sets of gas turbine and HRSGs associated to one steam turbine generator and condenser) with the developed model, assuming that every train operates identically and in steady state. The presented model was conceived from a complex configuration of a real power plant, over which variations may be applied in order to adapt it to a defined configuration under study [Borelli SJS. Method for the analysis of the composition of electricity costs in combined cycle thermoelectric power plants. Master in Energy Dissertation, Interdisciplinary Program of Energy, Institute of Eletro-technical and Energy, University of Sao Paulo, Sao Paulo, Brazil, 2005 (in Portuguese)]. The variations and adaptations include, for instance, use of reheat, supplementary firing and partial load operation. It is also possible to undertake sensitivity analysis on geometrical equipment parameters. (author)

  4. Exergy-based method for analyzing the composition of the electricity cost generated in gas-fired combined cycle plants

    International Nuclear Information System (INIS)

    Sarraf Borelli, Samuel Jose; Oliveira Junior, Silvio de

    2008-01-01

    The proposed method to analyze the composition of the cost of electricity is based on the energy conversion processes and the destruction of the exergy through the several thermodynamic processes that comprise a combined cycle power plant. The method uses thermoeconomics to evaluate and allocate the cost of exergy throughout the processes, considering costs related to inputs and investment in equipment. Although the concept may be applied to any combined cycle or cogeneration plant, this work develops only the mathematical modeling for three-pressure heat recovery steam generator (HRSG) configurations and total condensation of the produced steam. It is possible to study any nx1 plant configuration (n sets of gas turbine and HRSGs associated to one steam turbine generator and condenser) with the developed model, assuming that every train operates identically and in steady state. The presented model was conceived from a complex configuration of a real power plant, over which variations may be applied in order to adapt it to a defined configuration under study [Borelli SJS. Method for the analysis of the composition of electricity costs in combined cycle thermoelectric power plants. Master in Energy Dissertation, Interdisciplinary Program of Energy, Institute of Eletro-technical and Energy, University of Sao Paulo, Sao Paulo, Brazil, 2005 (in Portuguese)]. The variations and adaptations include, for instance, use of reheat, supplementary firing and partial load operation. It is also possible to undertake sensitivity analysis on geometrical equipment parameters

  5. Energy and exergy utilization in transportation sector of Saudi Arabia

    International Nuclear Information System (INIS)

    Dincer, I.; Hussain, M.M.; Al-Zaharnah, I.

    2004-01-01

    In this paper we present an analysis of energy and exergy utilization in the transportation sector of Saudi Arabia by considering the sectoral energy and exergy flows for the years of 1990-2001. Energy and exergy analyses are conducted for its three subsectors, namely road, air and marine, and hence the energy and exergy efficiencies are obtained for comparison. Road subsector appears to be the most efficient one compared to air and marine subsectors. It is found that the energy efficiencies in air and marine subsectors are found to be equal to the corresponding exergy efficiencies due to the values of exergy grade function. A comparison of the overall energy and exergy efficiencies of Saudi Arabian transportation sector with the Turkish transportation sector is also presented for the year 1993 based on the data available. Although the sectoral coverage is not same for both countries, it is still useful to illustrate the situation on how subsectoral energy and exergy efficiencies vary over the years. Turkish transportation sector appears to be a bit more efficient for that particular year. It is believed that the present technique is practical and useful for analyzing sectoral energy and exergy utilization to determine how efficient energy and exergy are used in transportation sector. It is also be helpful to establish standards, based on exergy, to facilitate applications in industry and in other planning processes such as energy planning

  6. Quantifying global exergy resources

    International Nuclear Information System (INIS)

    Hermann, Weston A.

    2006-01-01

    Exergy is used as a common currency to assess and compare the reservoirs of theoretically extractable work we call energy resources. Resources consist of matter or energy with properties different from the predominant conditions in the environment. These differences can be classified as physical, chemical, or nuclear exergy. This paper identifies the primary exergy reservoirs that supply exergy to the biosphere and quantifies the intensive and extensive exergy of their derivative secondary reservoirs, or resources. The interconnecting accumulations and flows among these reservoirs are illustrated to show the path of exergy through the terrestrial system from input to its eventual natural or anthropogenic destruction. The results are intended to assist in evaluation of current resource utilization, help guide fundamental research to enable promising new energy technologies, and provide a basis for comparing the resource potential of future energy options that is independent of technology and cost

  7. Energy, exergy and sustainability analyses of hybrid renewable energy based hydrogen and electricity production and storage systems: Modeling and case study

    International Nuclear Information System (INIS)

    Caliskan, Hakan; Dincer, Ibrahim; Hepbasli, Arif

    2013-01-01

    In this study, hybrid renewable energy based hydrogen and electricity production and storage systems are conceptually modeled and analyzed in detail through energy, exergy and sustainability approaches. Several subsystems, namely hybrid geothermal energy-wind turbine-solar photovoltaic (PV) panel, inverter, electrolyzer, hydrogen storage system, Proton Exchange Membrane Fuel Cell (PEMFC), battery and loading system are considered. Also, a case study, based on hybrid wind–solar renewable energy system, is conducted and its results are presented. In addition, the dead state temperatures are considered as 0 °C, 10 °C, 20 °C and 30 °C, while the environment temperature is 30 °C. The maximum efficiencies of the wind turbine, solar PV panel, electrolyzer, PEMFC are calculated as 26.15%, 9.06%, 53.55%, and 33.06% through energy analysis, and 71.70%, 9.74%, 53.60%, and 33.02% through exergy analysis, respectively. Also, the overall exergy efficiency, ranging from 5.838% to 5.865%, is directly proportional to the dead state temperature and becomes higher than the corresponding energy efficiency of 3.44% for the entire system. -- Highlights: ► Developing a three-hybrid renewable energy (geothermal–wind–solar)-based system. ► Undertaking a parametric study at various dead state temperatures. ► Investigating the effect of dead state temperatures on exergy efficiency

  8. Preliminary Assessment of Noise Pollution Prevention in Wind Turbines Based on an Exergy Approach

    Directory of Open Access Journals (Sweden)

    Ofelia A. Jianu

    2017-06-01

    Full Text Available Most existing methods for energy transformation and use are inadvertently contaminating our watersupplies, releasing greenhouse gasses into the atmosphere, emitting compounds that diminish the earth'sprotective blanket of ozone, and depleting the earth's crust of natural resources. As a result, scientists andengineers are increasingly pursuing sustainable technologies so that costs associated with global warmingcan be minimized and adverse impact on living organisms can be prevented. A promising sustainablemethod is to harness energy from the wind via wind turbines. However, the noise generated by wind turbinesproves to be one of the most significant hindrances to the extensive use of wind turbines. In this study,noise generation produced by flow over objects is investigated to characterize the noise generated due toflow-structure interaction and aeroacoustics. As a benchmark, flow over a cylinder has been chosen for thisstudy, with the aim of correlating three main characteristics in noise generation. Hence, the generated soundpressure level, exergy destroyed and the normal flow velocity (∪ ∞ are employed to characterize the systemin order to relate the exergy destruction to the noise generated in the flow. The correlation has the potentialto be used in wind turbine designs to minimize noise pollution due to aerodynamic noise.

  9. The Characteristics of the Exergy Reference Environment and Its Implications for Sustainability-Based Decision-Making

    Directory of Open Access Journals (Sweden)

    Stephen Murphy

    2012-07-01

    Full Text Available In the energy realm there is a pressing need to make decisions in a complex world characterized by biophysical limits. Exergy has been promoted as a preferred means of characterizing the impacts of resource consumption and waste production for the purpose of improving decision-making. This paper provides a unique and critical analysis of universal and comprehensive formulations of the chemical exergy reference environment, for the purpose of better understanding how exergy can inform decision-making. Four related insights emerged from the analysis, notably: (1 standard and universal chemical exergy reference environments necessarily encounter internal inconsistencies and even contradictions in their very formulations; (2 these inconsistencies are a result of incompatibility between the exergy reference environment and natural environment, and the desire to model the exergy reference environment after the natural environment so as to maintain analytical relevance; (3 the topics for which exergy is most appropriate as an analytical tool are not well served by comprehensive reference environments, and (4 the inconsistencies point to a need for deeper reflection of whether it is appropriate to adopt a thermodynamic frame of analysis for situations whose relevant characteristics are non-thermodynamic (e.g., to characterize scarcity. The use of comprehensive reference environments may lead to incorrect recommendations and ultimately reduce its appeal for informing decision-making. Exergy may better inform decision-making by returning to process dependent reference states that model specific processes and situations for the purpose of engineering optimization.

  10. Exergy based parametric analysis of a combined reheat regenerative thermal power plant and water–LiBr vapor absorption refrigeration system

    International Nuclear Information System (INIS)

    Gogoi, T.K.; Talukdar, K.

    2014-01-01

    Highlights: • Exergy analysis of a combined power–absorption cooling system is provided. • Exergetic efficiency of the power cycle and absorption cooling system are calculated. • Irreversibility in each component and total system irreversibility are calculated. • Effect of operating parameters on exergetic performance and irreversibility is analyzed. • Optimum operating parameters are identified based on energy and exergy based results. - Abstract: In this paper, exergy analysis of a combined reheat regenerative steam turbine (ST) based power cycle and water–LiBr vapor absorption refrigeration system (VARS) is presented. Exergetic efficiency of the power cycle and VARS, energy utilization factor (EUF) of the combined system (CS) and irreversibility in each system component are calculated. The effect of fuel flow rate, boiler pressure, cooling capacity and VARS components’ temperature on performance, component and total system irreversibility is analyzed. The second law based results indicate optimum performance at 150 bar boiler pressure and VARS generator, condenser, evaporator and absorber temperature of 80 °C, 37.5 °C, 15 °C and 35 °C respectively. The present exergy based results conform well to the first law based results obtained in a previous analysis done on the same combined system. Irreversibility distribution among various power cycle components shows the highest irreversibility in the cooling tower. Irreversibility of the exhaust flue gas leaving the boiler and the boiler are the next major contributors. Among the VARS components, exergy destruction in the generator is the highest followed by irreversibility contribution of the absorber, condenser and the evaporator

  11. Exergy analysis of the energy use in Greece

    International Nuclear Information System (INIS)

    Koroneos, Christopher J.; Nanaki, Evanthia A.; Xydis, George A.

    2011-01-01

    In this work, an analysis is being done on the concept of energy and exergy utilization and an application to the residential and industrial sector of Greece. The energy and exergy flows over the period from 1990 to 2004 were taken into consideration. This period was chosen based on the data reliability. The energy and exergy efficiencies are calculated for the residential and industrial sectors and compared to the findings of a previous study concerning the exergy efficiency of the Greek transport sector. The residential energy and exergy efficiencies for the year 2003 were 22.36% and 20.92%, respectively, whereas the industrial energy and exergy efficiencies for the same year were 53.72% and 51.34%, respectively. The analysis of energy and exergy utilization determines the efficiency of the economy as a whole. The results can play an important role in the establishment of efficiency standards of the energy use in various economy sectors. These standards could be utilized by energy policy makers. - Research highlights: → This work analyzes energy and exergy utilization in the energy sector of Greece by considering the energy and exergy flows for the years of 1990-2004. → Energy and exergy analyses and hence efficiencies for the residential and industrial sector are then obtained and compared to transport energy and exergy efficiencies. → The industrial sector appears to be the most energy and exergy efficient one. → It should be noted that due to non-availability of data concerning the fuel energy consumption of the appliances as well as of industrial processes, a general methodology was employed in order to calculate the energy and exergy efficiencies. → It may also be concluded that the exergy analysis offers constructive suggestions for the optimization and improvement of the energy utilization effectiveness of the sectors under study.

  12. EXERGY ANALYSIS OF PRODUCTION LINE CANDIED FRUIT

    Directory of Open Access Journals (Sweden)

    V. D. Dem'шanov

    2014-01-01

    Full Text Available Summary. The task of exergy analysis - evaluation based on the second law of thermodynamics, thermodynamic degree of technical perfection of the whole system, as well as to identify those stages of a technical process, which contains the bulk of the loss of exergy in order to improve its efficiency. Using exergy analysis allows to solve a wide range of technical problems on the basis of a unified thermodynamic methods. Exergy analysis was performed by the method whereby thermotechnological system candied fruit production, conventionally separated from the environment of the closed control surface. Exchange scheme under consideration thermotechnological candied fruit production material, thermal and energy flows to the environment, as well as between the control surfaces. Exergy in external input material streams: air and water and citric acid, as well as output streams without having increment Shih-exergy in the process of passing through the reference surface - of running air-water and after washing, are in thermodynamic equilibrium with the surroundings is zero. In the total number of internal exergy losses include losses from the final result of the temperature difference in the heat exchange between the raw material to be dried and heated air electromechanical arising from irreversible alteration of structural and mechanical properties of the product, and the hydraulic loss due to the sudden increase of the specific volume of air as it enters the working chamber dryer. The resulting exergy efficiency is 8.87 %, which is 3.7 % higher than when using the technology of the prototype based on solar air-dried product. This indicates an increase in the degree of perfection of the thermodynamic system by using microwave heating of the product in combination with the removal of moisture in the atmosphere low temperature coolant, which precludes significant outside exergy loss on drying step.

  13. A comprehensive energy–exergy-based assessment and parametric study of a hydrogen production process using steam glycerol reforming

    International Nuclear Information System (INIS)

    Hajjaji, Noureddine; Chahbani, Amna; Khila, Zouhour

    2014-01-01

    Various assessment tools are applied to comprehensively investigate a glycerol-to-hydrogen production system. These tools investigate the chemical reactions, design and simulate the entire hydrogen production process, study the energetic and exergetic performances and perform parametric analyses (using intuitive and design of experiment-based methods). Investigating the chemical reaction of steam glycerol reforming reveals that the optimal conditions, determined based on maximizing the hydrogen production while minimizing the methane and carbon monoxide contents and coke formation, can be achieved at a reforming temperature and a water-to-glycerol feed ratio (WGFR) of 950 K and 9, respectively. The thermal and exergetic efficiencies of the resulting process are 66.6% and 59.9%, respectively. These findings are lower than those cited in the literature and relative to other reformates (methane, ethanol and methanol). The parametric investigation indicates that the performance of the process (energetic and exergetic) could be ensured by using an appropriate and judiciously selected combination of the reactor temperature and WGFR. Based on the parametric energetic and exergetic investigation, WGFR = 6 and T = 1100 K appear to be the most accurate parameters for the entire glycerol-to-hydrogen process. For this recommend configuration, the thermal and exergetic efficiencies are 78.1% and 66.1%, respectively. - Highlights: • Energy and exergy analysis are used to assess glycerol-to-hydrogen process. • Recommended conditions for glycerol-to-hydrogen process are WGFR = 6 and T = 1100 K. • For recommend conditions, thermal and exergetic efficiencies are 78.1% and 66.1%. • Energy and exergy consideration should be included by engineers and scientists

  14. An exergy method for compressor performance analysis

    Energy Technology Data Exchange (ETDEWEB)

    McGovern, J A; Harte, S [Trinity Coll., Dublin (Ireland)

    1995-07-01

    An exergy method for compressor performance analysis is presented. The purpose of this is to identify and quantify defects in the use of a compressor`s shaft power. This information can be used as the basis for compressor design improvements. The defects are attributed to friction, irreversible heat transfer, fluid throttling, and irreversible fluid mixing. They are described, on a common basis, as exergy destruction rates and their locations are identified. The method can be used with any type of positive displacement compressor. It is most readily applied where a detailed computer simulation program is available for the compressor. An analysis of an open reciprocating refrigeration compressor that used R12 refrigerant is given as an example. The results that are presented consist of graphs of the instantaneous rates of exergy destruction according to the mechanisms involved, a pie chart of the breakdown of the average shaft power wastage by mechanism, and a pie chart with a breakdown by location. (author)

  15. Application of exergy as thermodynamic indicator in ecology

    International Nuclear Information System (INIS)

    Jorgensen, S.E.; Nors Nielsen, Soren

    2007-01-01

    We introduce a modified form of exergy named eco-exergy as an ecological indicator. Exergy of detritus and of various organisms are found based upon the definition of eco-exergy. Eco-exergy measures a system's deviation from chemical equilibrium. It is, therefore, crucial to find the concentration of detritus and the various organisms at chemical equilibrium which is possible by the calculation of the probability to form detritus and the various organisms by chemical equilibrium. It implies that the probability to form proteins with the right amino acid sequence must be determined by the use of the amount of coding genes. It is stressed that what we determine by this method of exergy calculation is a relative eco-exergy index. It is not possible to find the eco-exergy of entire ecosystems, because they are far too complex to allow us to know all the details of an ecosystem. The eco-exergy indices have been found in a few cases to demonstrate the usefulness of the method and to show how the exergy indices can be translated to applicable ecological information

  16. Exergy analysis of a combined power and cooling cycle

    International Nuclear Information System (INIS)

    Fontalvo, Armando; Pinzon, Horacio; Duarte, Jorge; Bula, Antonio; Quiroga, Arturo Gonzalez; Padilla, Ricardo Vasquez

    2013-01-01

    This paper presents a comprehensive exergy analysis of a combined power and cooling cycle which combines a Rankine and absorption refrigeration cycle by using ammonia–water mixture as working fluid. A thermodynamic model was developed in Matlab ® to find out the effect of pressure ratio, ammonia mass fraction at the absorber and turbine efficiency on the total exergy destruction of the cycle. The contribution of each cycle component on the total exergy destruction was also determined. The results showed that total exergy destruction decreases when pressure ratio increases, and reaches a maximum at x ≈ 0.5, when ammonia mass fraction is varied at absorber. Also, it was found that the absorber, the boiler and the turbine had the major contribution to the total exergy destruction of the cycle, and the increase of the turbine efficiency reduces the total exergy destruction. The effect of rectification cooling source (external and internal) on the cycle output was investigated, and the results showed that internal rectification cooling reduces the total exergy destruction of the cycle. Finally, the effect of the presence or absence of the superheater after the rectification process was determined and it was obtained that the superheated condition reduces the exergy destruction of the cycle at high turbine efficiency values. Highlights: • A parametric exergy analysis of a combined power and cooling cycle is performed. • Two scenarios for rectifier cooling (internal and external) were studied. • Internal cooling source is more exergetic efficient than external cooling source. • The absorber and boiler have the largest total exergy destruction. • Our results show that the superheater reduces the exergy destruction of the cycle

  17. Advances in exergy analysis: a novel assessment of the Extended Exergy Accounting method

    International Nuclear Information System (INIS)

    Rocco, M.V.; Colombo, E.; Sciubba, E.

    2014-01-01

    Highlights: • General overview of exergy-based methods for system analysis is presented. • Taxonomy for exergy-based methods classification is proposed. • Theoretical foundations and details of Extended Exergy Accounting are described. - Abstract: Objective: This paper presents a theoretical reassessment of the Extended Exergy Accounting method (EEA in the following), a comprehensive exergy-based analytical paradigm for the evaluation of the total equivalent primary resource consumption in a generic system. Our intent in this paper was to rigorously review the EEA theory and to highlight its double “valence” as a resource quantifier and to clarify its operative potential. On the one side, EEA can be properly regarded as a general “costing” theory based on a proper knowledge of the cumulative exergy consumption of different supply chains, economic systems and labour market: it is indeed the only method that translates externalities (capital, labour and environmental remediation) into cumulative exergetic costs and thus allows for their rigorous inclusion in a comprehensive resource cost assessment. Indeed, the extended exergy cost eec reflects both the thermodynamic “efficiency” of the production chain and the “hidden” resource costs for the society as a whole. From another, perhaps even more innovative, perspective, EEA can be viewed as a space and time dependent methodology since economic and labour costs can only be included in the Extended Exergy balance via their exergy equivalents (via two rigorously defined postulates). Since the equivalent exergy cost of the externalities depends both on the type of society and on the time window of the analysis, the extended exergy cost eec reflects in a very real sense both the thermodynamic “efficiency” of the machinery and the “conversion efficiency” of the specific society within which the analysis is performed. We argue that these two intrinsic features of the EEA method provide both

  18. Exergy analysis of a gas-hydrate cool storage system

    International Nuclear Information System (INIS)

    Bi, Yuehong; Liu, Xiao; Jiang, Minghe

    2014-01-01

    Based on exergy analysis of charging and discharging processes in a gas-hydrate cool storage system, the formulas for exergy efficiency at the sensible heat transfer stage and the phase change stage corresponding to gas-hydrate charging and discharging processes are obtained. Furthermore, the overall exergy efficiency expressions of charging, discharging processes and the thermodynamic cycle of the gas-hydrate cool storage system are obtained. By using the above expressions, the effects of number of transfer units, the inlet temperatures of the cooling medium and the heating medium on exergy efficiencies of the gas-hydrate cool storage system are emphatically analyzed. The research results can be directly used to evaluate the performance of gas-hydrate cool storage systems and design more efficient energy systems by reducing the sources of inefficiency in gas-hydrate cool storage systems. - Highlights: • Formulas for exergy efficiency at four stages are obtained. • Exergy efficiency expressions of two processes and one cycle are obtained. • Three mainly influencing factors on exergy efficiencies are analyzed. • With increasing the inlet temperature of cooling medium, exergy efficiency increases. • With decreasing the inlet temperature of heating medium, exergy efficiency increases

  19. Energy, exergy and economic assessments of a novel integrated biomass based multigeneration energy system with hydrogen production and LNG regasification cycle

    International Nuclear Information System (INIS)

    Taheri, M.H.; Mosaffa, A.H.; Farshi, L. Garousi

    2017-01-01

    In this work, a novel integrated biomass based multigeneration energy system is presented and investigated for power, cooling and hydrogen production. The proposed system consists of a combination of biomass integrated gasifier-gas turbine cycle, a Rankine cycle, a cascade organic Rankine cycle, an absorption refrigeration system and a PEM to produce hydrogen. This system uses cold energy of LNG as a thermal sink. Comprehensive thermodynamic and economic analyses as well as an optimization are performed. The effects of operating parameters on thermodynamic performance and total cost rate are investigated for overall system and subsystems. The results show that the fuel mass flow rate is the dominant factor affecting the variation of energy efficiency and total cost rate. An increase in fuel mass flow rate from 4 kg s"−"1 to 10 kg s"−"1 leads to a decrease of 8.5% and an increase of 122.8% overall energy efficiency and total cost rate, respectively. Also, the largest increase in exergy efficiency occurs when gas turbine inlet temperature increases. The results of optimization showed that the highest net power output, mass flow rate of natural gas delivered to city and the flue gas temperature discharged to the environment are obtained for the exergy efficiency optimal design. - Highlights: • A novel multigeneration system is investigated and optimized thermodynamically and economically. • This system is proposed for power, cooling and hydrogen production. • Proposed system uses LNG cold energy thermal sink that can generate power after vaporization. • The effects of operating parameters on energy and exergy efficiencies and total cost rate are investigated. • An optimization is applied based on the energy, exergy and economic viewpoints.

  20. Exergy and Exergoeconomic Model of a Ground-Based CAES Plant for Peak-Load Energy Production

    Directory of Open Access Journals (Sweden)

    Giampaolo Manfrida

    2013-02-01

    Full Text Available Compressed Air Energy Storage is recognized as a promising technology for applying energy storage to grids which are more and more challenged by the increasing contribution of renewable such as solar or wind energy. The paper proposes a medium-size ground-based CAES system, based on pressurized vessels and on a multiple-stage arrangement of compression and expansion machinery; the system includes recovery of heat from the intercoolers, and its storage as sensible heat in two separate (hot/cold water reservoirs, and regenerative reheat of the expansions. The CAES plant parameters were adapted to the requirements of existing equipment (compressors, expanders and heat exchangers. A complete exergy analysis of the plant was performed. Most component cost data were procured from the market, asking specific quotations to the industrial providers. It is thus possible to calculate the final cost of the electricity unit (kWh produced under peak-load mode, and to identify the relative contribution between the two relevant groups of capital and component inefficiencies costs.

  1. Effect of reference environment on the turbofan engine with the aid of specific-exergy based methods

    Energy Technology Data Exchange (ETDEWEB)

    Turan, Onder [Anadolu University, School of Civil Aviation (Turkey)], e-mail: onderturan@anadolu.edu.tr

    2011-07-01

    Research is being carried out in the aeronautics sector on improving engine efficiency, and thereby increasing engine power, while reducing fuel consumption. The aim of this study was to determine the performance and efficiency of a turbofan engine and assess the impact of altitude on its performance. An exergetic analysis was carried out at different altitudes on a simple turbofan engine composed of inlet, fan, high pressure compressor and turbine, fan nozzle, compression chamber and exhaust. Exergy analysis allows the loss locations to be assessed and efficiencies evaluated in a meaningful way. Results showed that the turbofan engine has an efficiency of 25.68% to 28.11% and an exergy efficiency of 48.91% to 50.34%. It was found, moreover, that the combustion chamber was where the greatest efficiency losses occurred. This study permitted the exergy performance of a turbofan engine to be determined and identified the components where the greater losses occurred.

  2. Adopting exergy analysis for use in aerospace

    Science.gov (United States)

    Hayes, David; Lone, Mudassir; Whidborne, James F.; Camberos, José; Coetzee, Etienne

    2017-08-01

    Thermodynamic analysis methods, based on an exergy metric, have been developed to improve system efficiency of traditional heat driven systems such as ground based power plants and aircraft propulsion systems. However, in more recent years interest in the topic has broadened to include applying these second law methods to the field of aerodynamics and complete aerospace vehicles. Work to date is based on highly simplified structures, but such a method could be shown to have benefit to the highly conservative and risk averse commercial aerospace sector. This review justifies how thermodynamic exergy analysis has the potential to facilitate a breakthrough in the optimization of aerospace vehicles based on a system of energy systems, through studying the exergy-based multidisciplinary design of future flight vehicles.

  3. Exergy analysis of gas turbine with air bottoming cycle

    International Nuclear Information System (INIS)

    Ghazikhani, M.; Khazaee, I.; Abdekhodaie, E.

    2014-01-01

    In this paper, the exergy analysis of a conventional gas turbine and a gas turbine with air bottoming cycle (ABC) is presented in order to study the important parameters involved in improving the performance characteristics of the ABC based on the Second Law of thermodynamics. In this study, work output, specific fuel consumption (SFC) and the exergy destruction of the components are investigated using a computer model. The variations of the ABC cycle exergy parameters are comprehensively discussed and compared with those of the simple gas turbine. The results indicate that the amount of the exhaust exergy recovery in different operating conditions varies between 8.6 and 14.1% of the fuel exergy, while the exergy destruction due to the extra components in the ABC makes up only 4.7–7.4% of the fuel exergy. This is the reason why the SFC of the ABC is averagely 13.3% less and the specific work 15.4% more than those of the simple gas turbine. The results also reveal that in the ABC cycle, at a small value of pressure ratio, a higher specific work with lower SFC can be achieved in comparison with those of the simple gas turbine. - Highlights: • Exhaust exergy recovery in ABC gas turbine varies with 8.6–14.1% of the fuel exergy. • Irreversibility of the extra devices in ABC makes up 4.7–7.4% of the fuel exergy. • SFC in ABC is poor due to exergy recovery more than extra devices irreversibility. • At the same TIT and R c , specific work in the ABC is more than simple gas turbine. • The recuperator has the largest contribution in the irreversibility of the ABC

  4. Exergy Flows inside a One Phase Ejector for Refrigeration Systems

    Directory of Open Access Journals (Sweden)

    Mohammed Khennich

    2016-03-01

    Full Text Available The evaluation of the thermodynamic performance of the mutual transformation of different kinds of exergy linked to the intensive thermodynamic parameters of the flow inside the ejector of a refrigeration system is undertaken. Two thermodynamic metrics, exergy produced and exergy consumed, are introduced to assess these transformations. Their calculation is based on the evaluation of the transiting exergy within different ejector sections taking into account the temperature, pressure and velocity variations. The analysis based on these metrics has allowed pinpointing the most important factors affecting the ejector’s performance. A new result, namely the temperature rise in the sub-environmental region of the mixing section is detected as an important factor responsible for the ejector’s thermodynamic irreversibility. The overall exergy efficiency of the ejector as well as the efficiencies of its sections are evaluated based on the proposed thermodynamic metrics.

  5. Exergy destruction in ammonia scrubbers

    NARCIS (Netherlands)

    Zisopoulos, Filippos K.; Goot, van der Atze Jan; Boom, Remko M.

    2018-01-01

    A theoretical ammonia scrubbing process by sulfuric acid solution is assessed with the concept of exergy. The exergy destruction of chemical neutralization is mainly (75–94%) due to changes in the chemical exergy of streams and thermal effects from the reaction while mixing effects have a limited

  6. Exergy and Exergoenvironmental Analysis of a CCHP System Based on a Parallel Flow Double-Effect Absorption Chiller

    Directory of Open Access Journals (Sweden)

    Ali Mousafarash

    2016-01-01

    Full Text Available A combined cooling, heating, and power (CCHP system which produces electricity, heating, and cooling is modeled and analyzed. This system is comprised of a gas turbine, a heat recovery steam generator, and a double-effect absorption chiller. Exergy analysis is conducted to address the magnitude and the location of irreversibilities. In order to enhance understanding, a comprehensive parametric study is performed to see the effect of some major design parameters on the system performance. These design parameters are compressor pressure ratio, gas turbine inlet temperature, gas turbine isentropic efficiency, compressor isentropic efficiency, and temperature of absorption chiller generator inlet. The results show that exergy efficiency of the CCHP system is higher than the power generation system and the cogeneration system. In addition, the results indicate that when waste heat is utilized in the heat recovery steam generator, the greenhouse gasses are reduced when the fixed power output is generated. According to the parametric study results, an increase in compressor pressure ratio shows that the network output first increases and then decreases. Furthermore, an increase in gas turbine inlet temperature increases the system exergy efficiency, decreasing the total exergy destruction rate consequently.

  7. Numerical Calculation and Exergy Equations of Spray Heat Exchanger Attached to a Main Fan Diffuser

    Science.gov (United States)

    Cui, H.; Wang, H.; Chen, S.

    2015-04-01

    In the present study, the energy depreciation rule of spray heat exchanger, which is attached to a main fan diffuser, is analyzed based on the second law of thermodynamics. Firstly, the exergy equations of the exchanger are deduced. The equations are numerically calculated by the fourth-order Runge-Kutta method, and the exergy destruction is quantitatively effected by the exchanger structure parameters, working fluid (polluted air, i.e., PA; sprayed water, i.e., SW) initial state parameters and the ambient reference parameters. The results are showed: (1) heat transfer is given priority to latent transfer at the bottom of the exchanger, and heat transfer of convection and is equivalent to that of condensation in the upper. (2) With the decrease of initial temperature of SW droplet, the decrease of PA velocity or the ambient reference temperature, and with the increase of a SW droplet size or initial PA temperature, exergy destruction both increase. (3) The exergy efficiency of the exchanger is 72.1 %. An approach to analyze the energy potential of the exchanger may be provided for engineering designs.

  8. Combined solar organic Rankine cycle with reverse osmosis desalination process: Energy, exergy, and cost evaluations

    Energy Technology Data Exchange (ETDEWEB)

    Nafey, A.S.; Sharaf, M.A. [Department of Engineering Science, Faculty of Petroleum and Mining Engineering, Suez Canal University, Suez (Egypt)

    2010-11-15

    Organic Rankine cycles (ORC) have unique properties that are well suited to solar power generation. In this work design and performance calculations are performed using MatLab/SimuLink computational environment. The cycle consists of thermal solar collectors (Flat Plate Solar Collector (FPC), or Parabolic Trough Collector (PTC), or Compound Parabolic Concentrator (CPC)) for heat input, expansion turbine for work output, condenser unit for heat rejection, pump unit, and Reverse Osmosis (RO) unit. Reverse osmosis unit specifications used in this work is based on Sharm El-Shiekh RO desalination plant. Different working fluids such as: butane, isobutane, propane, R134a, R152a, R245ca, and R245fa are examined for FPC. R113, R123, hexane, and pentane are investigated for CPC. Dodecane, nonane, octane, and toluene are allocated for PTC. The proposed process units are modeled and show a good validity with literatures. Exergy and cost analysis are performed for saturation and superheated operating conditions. Exergy efficiency, total exergy destruction, thermal efficiency, and specific capital cost are evaluated for direct vapor generation (DVG) process. Toluene and Water achieved minimum results for total solar collector area, specific total cost and the rate of exergy destruction. (author)

  9. Thermodynamic analysis and optimization of an integrated Rankine power cycle and nano-fluid based parabolic trough solar collector

    International Nuclear Information System (INIS)

    Toghyani, Somayeh; Baniasadi, Ehsan; Afshari, Ebrahim

    2016-01-01

    Highlights: • The performance of an integrated nano-fluid based solar Rankine cycle is studied. • The effect of solar intensity, ambient temperature, and volume fraction is evaluated. • The concept of Finite Time Thermodynamics is applied. • It is shown that CuO/oil nano-fluid has the best performance from exergy perspective. - Abstract: In this paper, the performance of an integrated Rankine power cycle with parabolic trough solar system and a thermal storage system is simulated based on four different nano-fluids in the solar collector system, namely CuO, SiO_2, TiO_2 and Al_2O_3. The effects of solar intensity, dead state temperature, and volume fraction of different nano-particles on the performance of the integrated cycle are studied using second law of thermodynamics. Also, the genetic algorithm is applied to optimize the net output power of the solar Rankine cycle. The solar thermal energy is stored in a two-tank system to improve the overall performance of the system when sunlight is not available. The concept of Finite Time Thermodynamics is applied for analyzing the performance of the solar collector and thermal energy storage system. This study reveals that by increasing the volume fraction of nano-particles, the exergy efficiency of the system increases. At higher dead state temperatures, the overall exergy efficiency is increased, and higher solar irradiation leads to considerable increase of the output power of the system. It is shown that among the selected nano-fluids, CuO/oil has the best performance from exergy perspective.

  10. Molar exergy and flow exergy of pure chemical fuels

    International Nuclear Information System (INIS)

    Zanchini, Enzo; Terlizzese, Tiziano

    2009-01-01

    Expressions of the molar exergy and of the molar flow exergy of a pure chemical fuel are deduced rigorously from the basic principles of thermodynamics. It is shown that molar exergy and molar flow exergy coincide when the temperature T and the pressure p of the fuel are equal to the temperature T B and the pressure p B of the environment; a general relation between exergy and flow exergy is proved as a consequence. The deduction of the expression of the molar exergy of a chemical fuel for non-standard values of T B and p B is clarified. For hydrogen, carbon dioxide and several hydrocarbons, tables are reported to allow a simple calculation of the molar exergy of the fuel for any value of the temperature T B and the relative humidity φ B of the environment, in the range 268.15 K ≤ T B ≤ 313.15 K and 0.1 ≤ φ B ≤ 1, with reference to the standard atmospheric pressure. Additional tables are provided to evaluate the difference between the exergy or the flow exergy of the fuel in its given initial state and the exergy at T = T B and p = p B . In these tables, it is assumed that fuel and environment have the same temperature and that the fuel pressure varies in the range 1.01325 bar ≤ p ≤ 200 bar; the fuel may be gas or liquid.

  11. Exergy analysis of an industrial unit of catalyst regeneration based on the results of modeling and simulation

    International Nuclear Information System (INIS)

    Toghyani, Mahboubeh; Rahimi, Amir

    2015-01-01

    An industrial process is synthesized and developed for decoking of de-hydrogenation catalyst, used in LAB (Linear Alkyl Benzene) production. A multi-tube fixed bed reactor, with short length tubes is designed for decoking of catalyst as the main equipment of the process. This study provides a microscopic exergy analysis for decoking reactor and a macroscopic exergy analysis for synthesized regeneration process. The dynamic mathematical modeling technique and the simulation of process by a commercial software are applied simultaneously. The used model was previously developed for performance analysis of decoking reactor. An appropriate exergy model is developed and adopted to estimate the enthalpy, exergetic efficiency and irreversibility. The model is validated with respect to some operating data measured in a commercial regeneration unit for variations in gas and particle characteristics along the reactor. In coke-combustion period, in spite of high reaction rate, the reactor has low exergetic efficiency due to entropy production during heat and mass transfer processes. The effects of inlet gas flow rate, temperature and oxygen concentration are investigated on the exergetic efficiency and irreversibilities. Macroscopic results indicate that the fan has the highest irreversibilities among the other equipment. Applying proper operating variables reduces the cycle irreversibilities at least by 20%. - Highlights: • A microscopic exergy analysis for a multi-tube fixed bed reactor is conducted. • Controlling the O_2 concentration upgrades the reactor exergetic performance. • A macroscopic exergy analysis for synthesized regeneration process is conducted. • The fan is one of the main sources of the regeneration cycle irreversibility. • The proposed strategies can reduce the cycle irreversibilities at least by 20%.

  12. Exergy outcomes associated with the greenhouse effects

    International Nuclear Information System (INIS)

    Valero, A.; Arauzo, I.

    1991-01-01

    In this paper the effect on the exergy of the Earth's fossil fuels if natural environmental conditions are changed due to the greenhouse effect is studied. The change considered here is a temperature rise produced as a result of increased CO 2 concentration. The temperature change due to the increase in CO 2 concentration is modeled in accordance with the most recent studies on the greenhouse effect. The result is that the ''average fossil fuel'', based on estimates of proven reserves, will lose 0.3% of its exergy if the atmospheric concentration of CO 2 doubles. Assuming that CO 2 concentration will double over the next hundred years, this 0.3% exergy loss of proven reserves means that we will lose as much capacity to produce work as primary energy was consumed in USA and Canada during 1988

  13. Exergy analysis of a 1000 MW double reheat ultra-supercritical power plant

    International Nuclear Information System (INIS)

    Si, Ningning; Zhao, Zhigang; Su, Sheng; Han, Pengshuai; Sun, Zhijun; Xu, Jun; Cui, Xiaoning; Hu, Song; Wang, Yi; Jiang, Long; Zhou, Yingbiao; Chen, Gang; Xiang, Jun

    2017-01-01

    Highlights: • Set up a simple and effective method to analysis the performance of double reheat USC unit. • Exergy loss distribution of the double reheat USC unit was declared. • The sensitivity variations of the unit’s exergy efficiency has been revealed. • Provide the foundation for the operation optimization of double reheat USC unit. - Abstract: This study evaluates the performance of a 1000 MW double reheat ultra-supercritical power plant. An exergy analysis was performed to direct the energy loss distribution of this system. Based on the exergy balance equation, together with exergy efficiency, exergy loss coefficient, and exergy loss rate, the exergy distribution and efficiency of the unit were determined. Results show that the highest exergy loss in furnace is as high as 85%, which caused by the combustion of fuel and heat exchange of water wall. The VHP and the two LPs suffer the highest exergy losses, namely 1.86%, 2.04% and 2.13% respectively. The regenerative heating system has an exergy loss rate of 2.3%. The condenser suffers a heat loss of 999 MW, but its exergy is as low as 20.49 MW. The sensitivity variations of the unit’s exergy efficiency with load, feedwater temperature, main steam temperature and pressure, the twice reheat steam temperatures, and steam exhaust pressure were also analyzed, indicating that load, feedwater temperature, and steam exhaust pressure influence the exergy efficiency of this unit than other elements. The overall exergy efficiency decreases along with the gradual increase of steam exhaust pressure at any constant outlet boiler temperature, but it increases as the load, feedwater temperature, main steam temperature and pressure, and twice reheat steam temperatures increase at fixed steam exhaust pressure.

  14. Comprehensive exergy analysis of a commercial tomato paste plant with a double-effect evaporator

    International Nuclear Information System (INIS)

    Mojarab Soufiyan, Mohamad; Dadak, Ali; Hosseini, Seyed Sina; Nasiri, Farshid; Dowlati, Majid; Tahmasebi, Maryam; Aghbashlo, Mortaza

    2016-01-01

    In this study, a detailed exergy evaluation of a commercial tomato paste plant with a double-effect evaporator was conducted in order to provide information on the system thermodynamic inefficiencies. Using energy and exergy balance equations, all components of the plant were analyzed individually and their exergetic parameters were calculated on the basis of actual operational data. The required data were obtained from Nazchin tomato paste factory located in Tehran, Iran. In addition, it was attempted to quantify the exergy utilized for processing a given amount of the tomato paste. The results showed that over 82% of the total destroyed exergy in the plant occurred in the boiler combination as the main component wasting exergy. Furthermore, exergy analysis introduced this combination as the main equipment rejecting exergy to the ambient where 4.79% of its total exergy input was lost. The rational exergy efficiency of the first- and second-effect evaporative units was found to be 65.33% and 56.60%, respectively. The specific exergy consumption of the tomato paste production was also determined as 16.83 MJ/kg. Generally, exergy concept and its extensions could be served as a powerful assessment technique to optimize the design and performance of multiple-effect evaporation systems employed in food industry. - Highlights: • Exergy analysis of a tomato paste plant with a double-effect evaporator was done. • 82% of the total exergy destruction rate occurred in the boiler combination. • 16.83 MJ exergy was utilized for production of 1 kg tomato paste. • Optimal number of effects could be potentially found using exergy-based approaches.

  15. Splitting the exergy destruction into avoidable and unavoidable parts of a gas engine heat pump (GEHP) for food drying processes based on experimental values

    International Nuclear Information System (INIS)

    Gungor, Aysegul; Erbay, Zafer; Hepbasli, Arif; Gunerhan, Huseyin

    2013-01-01

    Highlights: • Advanced exergy analysis of a gas engine heat pump drying system for the first time. • Varying exergy efficiency values from 79.71% to 81.66% for the overall drying system. • Obtaining modified exergy efficiencies of 84.50–86.00% for the overall drying system. - Abstract: Some limitations in a conventional exergy analysis may be significantly reduced through an advanced exergy analysis. In this regard, the latter is a very useful tool to assess the real potential for improving a system component by splitting the exergy destruction into unavoidable and avoidable parts. This may provide a realistic measure to deduct the improvement potential for the thermodynamic efficiency of a component. For this purpose, improvement efforts are then made by focusing only on these avoidable parts. In this paper, a gas engine heat pump (GEHP) drying system was analyzed using both conventional and advanced exergy analyses. Three medicinal and aromatic plants (Foeniculum vulgare, Malva sylvestris L. and Thymus vulgaris) were dried in a pilot scale GEHP drier, which was designed, constructed and installed in Ege University, Izmir, Turkey. Drying experiments were performed at an air temperature of 45 °C with an air velocity of 1 m/s. For each system component, avoidable and unavoidable exergy destructions, modified exergy efficiency values and modified exergy destruction ratios were determined. Except for the compressor, the evaporator and the drying cabinet, most of the exergy destructions in the system components were avoidable and these avoidable parts can be reduced by design improvements. For the HP unit and the overall drying system, the values for exergy efficiency were obtained to be in the range of 82.51–85.11% and 79.71–81.66% while those for the modified exergy efficiency were calculated to be in the range of 85.70–89.26% and 84.50–86.00%, respectively

  16. The Exergy of Lift and Aircraft Exergy Flow Diagrams

    OpenAIRE

    Paulus, Jr., David; Gaggioli, Richard

    2010-01-01

    Aside from incidental, auxiliary loads, in level flight the principal load on the aircraft propulsion engine is the power required to provide the continuous lift. To construct an exergy flow diagram for an aircraft – for example, for the purpose of pinpointing inefficiencies and for costing – an expression is needed for the exergy delivered to and by the wings. That is, an expression is needed for the exergy of lift. The purpose of this paper is to present an expression de...

  17. Exergy analysis in industrial food processing

    NARCIS (Netherlands)

    Zisopoulos, F.K.

    2016-01-01

    The sustainable provision of food on a global scale in the near future is a very serious challenge. This thesis focuses on the assessment and design of sustainable industrial food production chains and processes by using the concept of exergy which is an objective metric based on the first and

  18. Is bioethanol a sustainable energy source? An energy-, exergy-, and emergy-based thermodynamic system analysis

    NARCIS (Netherlands)

    Liao, Wenjie; Heijungs, Reinout; Huppes, Gjalt

    2011-01-01

    Biofuels are widely seen as substitutes for fossil fuels to offset the imminent decline of oil production and to mitigate the emergent increase in GHG emissions. This view is, however, based on too simple an analysis, focusing on only one piece in the whole mosaic of the complex biofuel

  19. Framework for the Economic Analysis of Hybrid Systems Based on Exergy Consumption

    Energy Technology Data Exchange (ETDEWEB)

    Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cherry, Robert S. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Deason, Wesley R. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sabharwall, Piyush [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bragg-Sitton, Shannon M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Boardman, Richard D. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-08-01

    Starting from an overview of the dynamic behavior of the electricity market the need of the introduction of energy users that will provide a damping capability to the system is derived as also a qualitative analysis of the impact of uncertainty, both in the demand and supply side, is performed. Then it follows an introduction to the investment analysis methodologies based on the discounting of the cash flow, and then work concludes with the illustration and application of the exergonomic principles to provide a sound methodology for the cost accounting of the plant components to be used in the cash flow analysis.

  20. Energy and exergy performance analysis of a marine rotary desiccant air-conditioning system based on orthogonal experiment

    International Nuclear Information System (INIS)

    Zhu, Jun; Chen, Wu

    2014-01-01

    A novel marine rotary desiccant A/C (air-conditioning) system was developed and studied to improve energy utilization efficiency of ship A/C. The orthogonal experiment was first carried out to investigate the influence of various parameters of the marine rotary desiccant A/C system. During the orthogonal experiment the analysis of variance was used to exclude interference from the secondary influencing factor on system performance. The significant influencing factors of system were studied in great detail using the first and second laws of thermodynamics to find optimal setting parameters for best system performance. It is suggested from the analysis results that as regeneration temperature increases, the COP th (thermal coefficient of performance) and exergy efficiency of system (η e ) decreases by 46.9% and 38.8% respectively. They decrease in proportion to the increase of the temperature. η e reaches its maximum value of about 23.5% when the inlet humidity ratio of process air is 22 g/kg. Besides, the exergy loss of system concentrates on the regeneration air heater, the desiccant wheel and the regeneration air leaving the desiccant wheel, which account for 68.4%–81% of the total exergy loss. It can be concluded that applying the marine rotary desiccant A/C in high-temperature and high-humidity marine environment is advantageous. - Highlights: • Significant influencing factors of the system are found by the analysis of variance. • The change trends of the COP th and the η e are nearly proportional with the regeneration temperature. • The η e reaches its maximum value (about 23.5%) when the inlet humidity ratio of process air is 22 g/kg. • The contribution rate of the dry-bulb temperature of fresh air is up to 73.91% for the COP th . • Applying the marine rotary desiccant A/C in high-temperature and high-humidity marine environment is advantageous

  1. Energy and Exergy Analysis of Kalina Cycle for the Utilization of Waste Heat in Brine Water for Indonesian Geothermal Field

    Directory of Open Access Journals (Sweden)

    Nasruddin Nasruddin

    2015-04-01

    Full Text Available The utilization of waste heat in a power plant system—which would otherwise be released back to the environment—in order to produce additional power increases the efficiency of the system itself. The purpose of this study is to present an energy and exergy analysis of Kalina Cycle System (KCS 11, which is proposed to be utilized to generate additional electric power from the waste heat contained in geothermal brine water available in the Lahendong Geothermal power plant site in North Sulawesi, Indonesia. A modeling application on energy and exergy system is used to study the design of thermal system which uses KCS 11. To obtain the maximum power output and maximum efficiency, the system is optimized based on the mass fraction of working fluid (ammonia-water, as well as based on the turbine exhaust pressure. The result of the simulation is the optimum theoretical performance of KCS 11, which has the highest possible power output and efficiency. The energy flow diagram and exergy diagram (Grassman diagram was also presented for KCS 11 optimum system to give quantitative information regarding energy flow from the heat source to system components and the proportion of the exergy input dissipated in the various system components.

  2. Sugarcane exergy calculation; Calculo de la exergia de la cana de azucar

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez P, Maria I.; Nebra P, Silvia A. [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Energia]. E-mails: mariai@fem.unicamp.br.; sanebra@fem.unicamp.br; Martinez R, Arnaldo [Universidade de Oriente, Santiago de Cuba (Cuba). Facultad de Ingenieria Mecanica. Centro de Estudios de Refrigeracion Luis Fernando Brossard Perez]. E-mail: arnaldo@fim.ceefe.uo.edu.cu

    2000-07-01

    This paper presents a sugarcane exergy calculation, carried out considering the material as constituted by dry fiber and juice, being the last one that includes all the sucrose and water present in sugarcane. The variation intervals of sugarcane chemical composition and consequently the chemical composition of fibre and juice were obtained from a bibliography research. the finals results show that, the fibre exergy, as was considered totally dry and without sucrose, is a function of it chemical composition only. The quotient between the exergy and low calorific value has a middle value of 1,14 and the middle value of it exergy was 2329 kJ/kg of cane. Based on the environmental reference proposed by Szargut for the sugarcane juice exergy determination, it was obtained that the mixture component of the juice exergy has no piratical influence in the total exergy juice value, being the value of the reactive exergy component the determining of a middle value of sugarcane juice exergy of 2814,25 kJ/kg of juice and 2380Kj/Kg of cane. The sugarcane exergy value obtained for 8-18% of fiber, 75-82% of water and 14.5-22% of sucrose was 4709Kj/kg of cane. (author)

  3. Energy and exergy analysis of an annular shaft kiln with opposite burners

    International Nuclear Information System (INIS)

    Rong, Wenjie; Li, Baokuan; Qi, Fengsheng; Cheung, Sherman C.P.

    2017-01-01

    Highlights: • An OBASK is investigated for the energy and exergy performance. • The energy and exergy efficiency of the OBASK is of 63.6% and 35.7%, respectively. • The exergy destruction accounts for 44.5% of the total exergy input. - Abstract: Annular shaft kilns with opposite burners (OBASK) has been widely adopted due to the advantages of cost saving and easy controlling. Nonetheless, compared with the traditional annular shaft kiln, the OBASK is not favorable in terms of thermal performance and energy efficiency. Aiming to improve the thermal performance, a comprehensive energy and exergy analysis of an OBASK has been conducted based on the actual operational data obtained from on-site measurements. For making a thorough thermal analysis of the OBASK, special attentions have been focused in considering magnesium decomposition reaction and moisture in limestone in the methodology. The energy and exergy efficiencies are determined to be 63.6% and 35.7%, respectively. The exergy destruction is 44.0% of total exergy input of which fuel combustion causes 56.6% of the exergy destruction. Furthermore, the effects of CaO and moisture contents in limestone on energy and exergy efficiencies are analyzed. The results have demonstrated the potential energy saving of the OBASK and identified three proposed energy conservation measures. Improvement and effect of the three proposed measures on the thermal performance are verified via further analysis.

  4. Exergy analysis of the energy use in Greece

    DEFF Research Database (Denmark)

    Koroneos, C.J.; Nanaki, E.A.; Xydis, George

    2011-01-01

    In this work, an analysis is being done on the concept of energy and exergy utilization and an application to the residential and industrial sector of Greece. The energy and exergy flows over the period from 1990 to 2004 were taken into consideration. This period was chosen based on the data...... of the energy use in various economy sectors. These standards could be utilized by energy policy makers....

  5. Energy and exergy analyses of Angra-2 nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Marques, João G.O.; Costa, Antonella L.; Pereira, Claubia; Fortini, Ângela, E-mail: jgabrieloliveira2010@bol.com.br, E-mail: antonella@nuclear.ufmg.br, E-mail: claubia@nuclear.ufmg.br, E-mail: fortini@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

    2017-07-01

    Nuclear Power Plants (NPPs) based on Pressurized Water Reactors (PWRs) technology are considered an alternative to fossil fuels plants due to their reliability with low operational cost and low CO{sub 2} emissions. An example of PWR plant is Angra-2 built in Brazil. This NPP has a nominal electric power output of 1300 MW and made it possible for the country save its water resources during electricity generation from hydraulic plants, and improved Brazilian knowledge and technology in nuclear research area. Despite all these benefits, PWR plants generally have a relatively low thermal efficiency combined with a large amount of irreversibility generation or exergy destruction in their components, reducing their capacity to produce work. Because of that, it is important to assess such systems to understand how each component impacts on system efficiency. Based on that, the aim of this work is to evaluate Angra-2 by performing energy and exergy analyses to quantify the thermodynamic performance of this PWR plant and its components. The methodology consists in the development of a mathematical model in EES (Engineering Equation Solver) software based on thermodynamic states in addition to energy and exergy balance equations. According to the results, Angra 2 has energy efficiency of 36.18% and exergy efficiency of 49.24%. Reactor core is the most inefficient device in the NPP; it has exergy efficiency of 67.16% and is responsible for 63.88% of all exergy destroyed in Angra-2. (author)

  6. Sustainability Indicators for the Use of Resources—The Exergy Approach

    DEFF Research Database (Denmark)

    Koroneos, Christopher J.; Nanaki, Evanthia A.; Xydis, George

    2012-01-01

    , trends, and impacts. New thinking and research with regard to indicator frameworks, methodologies, and actual indicators are also needed. The value of the overall indicators depends on the production procedure of each material, and indicates their environmental impact. The use of “exergy indicators......” based on the exergy content of materials and the use of the second law of thermodynamics in this work presents the relationship between exergy content and environmental impact....

  7. Thermodynamic analysis of a solar-based multi-generation system with hydrogen production

    International Nuclear Information System (INIS)

    Ozturk, Murat; Dincer, Ibrahim

    2013-01-01

    Thermodynamic analysis of a renewable-based multi-generation energy production system which produces a number of outputs, such as power, heating, cooling, hot water, hydrogen and oxygen is conducted. This solar-based multi-generation system consists of four main sub-systems: Rankine cycle, organic Rankine cycle, absorption cooling and heating, and hydrogen production and utilization. Exergy destruction ratios and rates, power or heat transfer rates, energy and exergy efficiencies of the system components are carried out. Some parametric studies are performed in order to examine the effects of varying operating conditions (e.g., reference temperature, direct solar radiation and receiver temperature) on the exergy efficiencies of the sub-systems as well as the whole system. The solar-based multi-generation system which has an exergy efficiency of 57.35%, is obtained to be higher than using these sub-systems separately. The evaluation of the exergy efficiency and exergy destruction for the sub-systems and the overall system show that the parabolic dish collectors have the highest exergy destruction rate among constituent parts of the solar-based multi-generation system, due to high temperature difference between the working fluid and collector receivers. -- Highlights: ► Development of a new multi-generation system for solar-based hydrogen production. ► Investigation of exergy efficiencies and destructions in each process of the system. ► Evaluation of varying operating conditions on the exergy destruction and efficiency

  8. Exergy analysis of waste emissions from gas flaring

    Directory of Open Access Journals (Sweden)

    Olawale Saheed ISMAIL

    2016-07-01

    Full Text Available Gas flaring produces a stream of waste gases at high temperature and pressure which contains carbon monoxide, Hydrogen Sulphide etc. The resultant effect of which is detrimental to our planet and, consequently, to the life of both the living and the non-living things. It’s well known that gas flaring contributes in no small measure to the global warming. Exergy analysis is applied in this work to analyze waste emissions from gas flaring so as to have a model through which impact of gas flaring can be measured. The study considers both the thermo-mechanical exergy and the chemical exergy of these gases. Relevant data on gas flaring activities in the Niger-Delta region of Nigeria between the periods of fifteen (15 years was obtained from the Nigerian National Petroleum Corporation (NNPC. A computer program (Exergy Calculator was developed based on the equations generated in the Model. Exergy associated with gas flaring activities in Nigeria between the periods of 1998 through 2012 was calculated. The results show that 1 mscf (in thousand cubic feet of flared gases generate 0.000041 MWh of energy leading to a value of 440158.607 MWh of energy for the period under review.The analysis provides important conclusions and recommendations for improving oil platforms operationsin in order to safeguard the environment, health of the populace, and maximize recovered exergy from gas flaring.

  9. Exergy analysis of biomass organic Rankine cycle for power generation

    Science.gov (United States)

    Nur, T. B.; Sunoto

    2018-02-01

    The study examines proposed small biomass-fed Organic Rankine Cycle (ORC) power plant through exergy analysis. The system consists of combustion burner unit to utilize biomass as fuel, and organic Rankine cycle unit to produce power from the expander. The heat from combustion burner was transfered by thermal oil heater to evaporate ORC working fluid in the evaporator part. The effects of adding recuperator into exergy destruction were investigated. Furthermore, the results of the variations of system configurations with different operating parameters, such as the evaporating pressures, ambient temperatures, and expander pressures were analyzed. It was found that the largest exergy destruction occurs during processes are at combustion part, followed by evaporator, condenser, expander, and pump. The ORC system equipped with a recuperator unit exhibited good operational characteristics under wide range conditions compared to the one without recuperator.

  10. Exergy Analysis of Serpentine Thermosyphon Solar Water Heater

    Directory of Open Access Journals (Sweden)

    Muhammad Faisal Hasan

    2018-03-01

    Full Text Available The performance of a solar hot water system is assessed for heat pump and domestic heating applications. Thermodynamic analysis on a serpentine-type thermosyphon flat-plate solar heater is conducted using the Second Law of thermodynamics. Exergetic optimization is first performed to determine the parameters for the maximum exergy efficiency using MATLAB optimization toolbox. Geometric parameters (collector surface area, dimensions, and pipe diameter, optical parameters (transmittance absorptance product, ambient temperature, solar irradiation and operating parameters (mass flow rate, fluid temperature, and overall heat transfer (loss coefficient are accounted for in the optimization scheme. The exergy efficiency at optimum condition is found to be 3.72%. The results are validated using experimental data and found to be in good agreement. The analysis is further extended to the influence of various operating parameters on the exergetic efficiency. It is observed that optical and thermal exergy losses contribute almost 20%, whereas approximately 77% exergy destruction is contributed by the thermal energy conversion. Exergy destruction due to pressure drop is found negligible. The result of this analysis can be used for designing and optimization of domestic heat pump system and hot water application.

  11. Energy, exergy, economic (3E) analyses and multi-objective optimization of vapor absorption heat transformer using NSGA-II technique

    International Nuclear Information System (INIS)

    Jain, Vaibhav; Sachdeva, Gulshan

    2017-01-01

    Highlights: • Study includes energy, exergy and economic analyses of absorption heat transformer. • It addresses multi-objective optimization study using NSGA-II technique. • Total annual cost and total exergy destruction are simultaneously optimized. • Results with multi-objective optimized design are more acceptable than other. - Abstract: Present paper addresses the energy, exergy and economic (3E) analyses of absorption heat transformer (AHT) working with LiBr-H 2 O fluid pair. The heat exchangers namely absorber, condenser, evaporator, generator and solution heat exchanger are designed for the size and cost estimation of AHT. Later, the effect of operating variables is examined on the system performance, size and cost. Simulation studies showed a conflict between thermodynamic and economic performance of the system. The heat exchangers with lower investment cost showed high irreversible losses and vice versa. Thus, the operating variables of systems are determined economically as well as thermodynamically by implementing non-dominated sort genetic algorithm-II (NSGA-II) technique of multi-objective optimization. In present work, if the cost based optimized design is chosen, total exergy destruction is 2.4% higher than its minimum possible value; whereas, if total exergy based optimized design is chosen, total annual cost is 6.1% higher than its minimum possible value. On the other hands, total annual cost and total exergy destruction are only 1.0% and 0.8%, respectively more from their minimum possible values with multi-objective optimized design. Thus, the multi-objective optimized design of the AHT is best outcome than any other single-objective optimized designs.

  12. Optimization of operating parameters in a hybrid wind–hydrogen system using energy and exergy analysis: Modeling and case study

    International Nuclear Information System (INIS)

    Fakehi, Amir Hossein; Ahmadi, Somayeh; Mirghaed, Mohammad Rezaie

    2015-01-01

    Highlights: • The exergy analysis of a hybrid system of a wind turbine and PEM electrolyzer/fuel-cell has been performed. • Effects of various operating parameters on the exergy efficiency have been investigated. • The exergy and energy efficiency in each of hybrid system’s components have been compared. - Abstract: In this study, hybrid renewable energy system based on wind/electrolyzer/PEM fuel cell are conceptually modeled, and also, exergy and energy analysis are performed. The energy and exergy flows are investigated by the proposed model for Khaf region-Iran with high average wind speed and monsoon. Exergy and energy analysis framework is made based on thermodynamic, electro-chemical and mechanical model of the different component of hybrid system. Also, the effects of various operating parameters in exergy efficiency are calculated. The results show an optimum wind speed where the exergy efficiency and power coefficient is at maximum level, and also, when the ambient temperature start to be increased in wind turbine, the efficiencies decrease by a great deal for constant wind speeds. Also, the optimum temperature is calculated by exergy analysis in electrolyzer and fuel cell as 353 and the exergy efficiency of electrolyzer decreases by increasing the membrane thickness. Furthermore, pressure changes affect exergy and energy efficiency in PEM fuel cell. Finally, the electrolyzer and fuel cell efficiencies are calculated as 68.5% and 47% respectively.

  13. Exergy Analysis of a Ground-Coupled Heat Pump Heating System with Different Terminals

    Directory of Open Access Journals (Sweden)

    Xiao Chen

    2015-04-01

    Full Text Available In order to evaluate and improve the performance of a ground-coupled heat pump (GCHP heating system with radiant floors as terminals, an exergy analysis based on test results is performed in this study. The system is divided into four subsystems, and the exergy loss and exergy efficiency of each subsystem are calculated using the expressions derived based on exergy balance equations. The average values of the measured parameters are used for the exergy analysis. The analysis results show that the two largest exergy losses occur in the heat pump and terminals, with losses of 55.3% and 22.06%, respectively, and the lowest exergy efficiency occurs in the ground heat exchange system. Therefore, GCHP system designers should pay close attention to the selection of heat pumps and terminals, especially in the design of ground heat exchange systems. Compared with the scenario system in which fan coil units (FCUs are substituted for the radiant floors, the adoption of radiant floors can result in a decrease of 12% in heating load, an increase of 3.24% in exergy efficiency of terminals and an increase of 1.18% in total exergy efficiency of the system. The results may point out the direction and ways of optimizing GCHP systems.

  14. General methodology for exergy balance in ProSimPlus® process simulator

    International Nuclear Information System (INIS)

    Ghannadzadeh, Ali; Thery-Hetreux, Raphaële; Baudouin, Olivier; Baudet, Philippe; Floquet, Pascal; Joulia, Xavier

    2012-01-01

    This paper presents a general methodology for exergy balance in chemical and thermal processes integrated in ProSimPlus ® as a well-adapted process simulator for energy efficiency analysis. In this work, as well as using the general expressions for heat and work streams, the whole exergy balance is presented within only one software in order to fully automate exergy analysis. In addition, after exergy balance, the essential elements such as source of irreversibility for exergy analysis are presented to help the user for modifications on either process or utility system. The applicability of the proposed methodology in ProSimPlus ® is shown through a simple scheme of Natural Gas Liquids (NGL) recovery process and its steam utility system. The methodology does not only provide the user with necessary exergetic criteria to pinpoint the source of exergy losses, it also helps the user to find the way to reduce the exergy losses. These features of the proposed exergy calculator make it preferable for its implementation in ProSimPlus ® to define the most realistic and profitable retrofit projects on the existing chemical and thermal plants. -- Highlights: ► A set of new expressions for calculation of exergy of material streams is developed. ► A general methodology for exergy balance in ProSimPlus ® is presented. ► A panel of solutions based on exergy analysis is provided to help the user for modifications on process flowsheets. ► The exergy efficiency is chosen as a variable in a bi-criteria optimization.

  15. Collective systems:physical and information exergies.

    Energy Technology Data Exchange (ETDEWEB)

    Robinett, Rush D. III (.; ); Wilson, David Gerald

    2007-04-01

    Collective systems are typically defined as a group of agents (physical and/or cyber) that work together to produce a collective behavior with a value greater than the sum of the individual parts. This amplification or synergy can be harnessed by solving an inverse problem via an information-flow/communications grid: given a desired macroscopic/collective behavior find the required microscopic/individual behavior of each agent and the required communications grid. The goal of this report is to describe the fundamental nature of the Hamiltonian function in the design of collective systems (solve the inverse problem) and the connections between and values of physical and information exergies intrinsic to collective systems. In particular, physical and information exergies are shown to be equivalent based on thermodynamics and Hamiltonian mechanics.

  16. Exergy analysis of a turbofan engine for an unmanned aerial vehicle during a surveillance mission

    International Nuclear Information System (INIS)

    Şöhret, Yasin; Dinç, Ali; Karakoç, T. Hikmet

    2015-01-01

    In this study, an exergy analysis of a turbofan engine, being the main power unit of an UAV (unmanned aerial vehicle) over the course of a surveillance mission flight, is presented. In this framework, an engine model is firstly developed, based upon engine design parameters and conditions using a genuine code. Next, the exergy analysis is performed according to thermodynamic laws. At the end of the study, the combustion chamber is identified as the most irreversible component of the engine, while the high pressure turbine and compressor are identified as the most efficient components throughout the flight. The minimum exergy efficiency is 58.24% for the combustion chamber at the end of the ingress flight phase, while the maximum exergy efficiency is found to be 99.09% for the high pressure turbine at the start of the ingress flight phase and landing loiter. The highest exergy destruction within the engine occurs at landing loiter, take-off and start of climb, with rates of 16998.768 kW, 16820.317 kW and 16564.378 kW respectively. - Highlights: • This study reveals the exergy parameters of a turbofan engine for an UAV. • Exergy analysis is conducted for a complete surveillance mission flight. • Variation of exergy parameters of engine components during the flight is presented. • The impact of the environment conditions on exergy parameters is proven.

  17. Energy, exergy, environmental and economic analysis of industrial fired heaters based on heat recovery and preheating techniques

    International Nuclear Information System (INIS)

    Shekarchian, M.; Zarifi, F.; Moghavvemi, M.; Motasemi, F.; Mahlia, T.M.I.

    2013-01-01

    Highlights: • 4-E analysis of a typical industrial grade fired heater unit is studied. • This analysis is accomplished for the first time in this study. • Heat recovery and air preheating lead to substantial reduction in the fuel consumption. • The company’s current costs are tremendously reduced by these methods. • The methods lead to mitigation in GHG emission and to reduction in the associated taxes. - Abstract: Fired heaters are ubiquitous in both the petroleum and petrochemical industries, due to it being vital in their day to day operations. They form major components in petroleum refineries, petrochemical facilities, and processing units. This study was commissioned in order to analyze the economic benefits of incorporating both heat recovery and air preheating methods into the existing fired heater units. Four fired heater units were analyzed from the energy and environmental point of views. Moreover, the second law efficiency and the rate of irreversibility were also analyzed via the exergy analysis. Both analyses was indicative of the fact that the heat recovery process enhances both the first and second law efficiencies while simultaneously assisting in the production of high and low pressure water steam. The implementation and usage of the process improves the thermal and exergy efficiencies from 63.4% to 71.7% and 49.4%, to 54.8%, respectively. Additionally, the heat recovery and air preheating methods leads to a substantial reduction in fuel consumption, in the realm of up to 7.4%, while also simultaneously decreasing heat loss and the irreversibility of the unit. Nevertheless, the results of the economic analysis posits that although utilizing an air preheater unit enhances the thermal performance of the system, due to the air preheater’s capital and maintenance costs, incorporating an air preheater unit to an existing fired heater is not economically justifiable. Furthermore, the results of the sensitivity analysis and payback period

  18. Advantages and limitations of exergy indicators to assess sustainability of bioenergy and biobased materials

    International Nuclear Information System (INIS)

    Maes, Dries; Van Passel, Steven

    2014-01-01

    Innovative bioenergy projects show a growing diversity in biomass pathways, transformation technologies and end-products, leading to complex new processes. Existing energy-based indicators are not designed to include multiple impacts and are too constrained to assess the sustainability of these processes. Alternatively, indicators based on exergy, a measure of “qualitative energy”, could allow a more holistic view. Exergy is increasingly applied in analyses of both technical and biological processes. But sustainability assessments including exergy calculations, are not very common and are not generally applicable to all types of impact. Hence it is important to frame the use of exergy for inclusion in a sustainability assessment. This paper reviews the potentials and the limitations of exergy calculations, and presents solutions for coherent aggregation with other metrics. The resulting approach is illustrated in a case study. Within the context of sustainability assessment of bioenergy, exergy is a suitable metric for the impacts that require an ecocentric interpretation, and it allows aggregation on a physical basis. The use of exergy is limited to a measurement of material and energy exchanges with the sun, biosphere and lithosphere. Exchanges involving services or human choices are to be measured in different metrics. This combination provides a more inclusive and objective sustainability assessment, especially compared to standard energy- or carbon-based indicators. Future applications of this approach in different situations are required to clarify the potential of exergy-based indicators in a sustainability context. -- Highlights: • Innovative bioenergy projects require more advanced sustainability assessments to incorporate all environmental impacts. • Exergy-based indicators provide solutions for objective and robust measurements. • The use of exergy in a sustainability assessment is limited to material exchanges, excluding exchanges with society

  19. Applicability of entropy, entransy and exergy analyses to the optimization of the Organic Rankine Cycle

    International Nuclear Information System (INIS)

    Zhu, Yadong; Hu, Zhe; Zhou, Yaodong; Jiang, Liang; Yu, Lijun

    2014-01-01

    Graphical abstract: Fig. 3a. Variations of the evaluation parameters with evaporation temperature in the case of prescribed hot and cold streams for R123. Fig. 3(a) indicates that among the seven parameters, the minimum entropy generation rate, exergy destruction rate, entransy efficiency, revised entropy generation number and the maximum entransy loss rate are corresponding to the maximum output power. However, the minimum entransy dissipation rate does not associate with the output power variation, it can be explained as follow: the entransy dissipation is one part of the entransy loss rate besides entransy variation (work entransy) or does not consider the influence of work output on the change of entransy. - Highlights: • Theories of entropy, exergy and entransy are applied to the optimization of the ORC. • Two commonly utilized working fluids – R123 and N-pentane are chosen for comparison. • Variable evaporation temperature, hot stream temperature and mass flow rate are considered. • 3-D coordinates are utilized to observe the global variation of parameters. • The concept of entransy loss rate is appropriate for all the cases discussed in this paper. - Abstract: Based on the theories of entropy, entransy and exergy, the concepts of entropy generation rate, revised entropy generation number, exergy destruction rate, entransy loss rate, entransy dissipation rate and entransy efficiency are applied to the optimization of the Organic Rankine Cycle. Cycles operating on R123 and N-pentane have been compared in three common cases which are variable evaporation temperature, hot stream temperature and hot stream mass flow rate. The optimization goal is to produce maximum output power. Some numerical analyses and simulations are presented, and the results show that when both the hot and cold stream conditions are fixed, all the entropy principle, the exergy theory, the entransy loss rate and the entransy efficiency are applicable to the optimization of the

  20. Resource analysis of the Chinese society 1980-2002 based on exergy-Part 2: Renewable energy sources and forest

    International Nuclear Information System (INIS)

    Chen, B.; Chen, G.Q.

    2007-01-01

    This second part is the continuation of the first part on fossil fuels and energy minerals. The major renewable energy sources and forest products entering the Chinese society from 1980 to 2002, including sunlight, wind power, tidal power, wave power, geothermal power and heating, biomass, hydroelectric resource and forestry products, are calculated and analyzed in detail in this paper. The solar exergy inputs from solar photovoltaics and solar collectors, including water heater, solar oven and solar building, are calculated and discussed. The development of the wind power plant is presented. Major tidal power plants, which are still working, are addressed. Wave power devices and plants are introduced. Geothermal resources, mainly for power generation and heating, associated with distribution, are depicted. The utilization of biomass, embracing firewood, straw and biogas, which served as the main obtainable local resources for private consumption and production in the rural areas, is illustrated. Development of hydroelectric resources as complement to scarce fossil fuels is represented, of which the small hydropower project adapted for rural areas is emphasized. Finally, forest products from timber forest and economic forest are presented, with the forestation, reproducing, tending areas and sum of odd forestation trees being manifested

  1. Energy and exergy analysis of low temperature district heating network

    International Nuclear Information System (INIS)

    Li, Hongwei; Svendsen, Svend

    2012-01-01

    Low temperature district heating with reduced network supply and return temperature provides better match of the low quality building heating demand and the low quality heating supply from waste heat or renewable energy. In this paper, a hypothetical low temperature district heating network is designed to supply heating for 30 low energy detached residential houses. The network operational supply/return temperature is set as 55 °C/25 °C, which is in line with a pilot project carried out in Denmark. Two types of in-house substations are analyzed to supply the consumer domestic hot water demand. The space heating demand is supplied through floor heating in the bathroom and low temperature radiators in the rest of rooms. The network thermal and hydraulic conditions are simulated under steady state. A district heating network design and simulation code is developed to incorporate the network optimization procedure and the network simultaneous factor. Through the simulation, the overall system energy and exergy efficiencies are calculated and the exergy losses for the major district heating system components are identified. Based on the results, suggestions are given to further reduce the system energy/exergy losses and increase the quality match between the consumer heating demand and the district heating supply. -- Highlights: ► Exergy and energy analysis for low and medium temperature district heating systems. ► Different district heating network dimensioning methods are analyzed. ► Major exergy losses are identified in the district heating network and the in-house substations. ► Advantages to apply low temperature district heating are highlighted through exergy analysis. ► The influence of thermal by-pass on system exergy/energy performance is analyzed.

  2. Exergy analysis of offshore processes on North Sea oil and gas platforms

    DEFF Research Database (Denmark)

    Nguyen, Tuong-Van; Pierobon, Leonardo; Elmegaard, Brian

    2012-01-01

    generation. In this paper, the most thermodynamically inefficient processes are identified by performing an exergy analysis, based on models built with the simulation tools Aspen Plus®, DNA and Aspen HYSYS®. Results reveal that the total exergy destruction of the system amounts to 69.4 MW, while the total...

  3. Feasibility study of microalgal and jatropha biodiesel production plants: Exergy analysis approach

    International Nuclear Information System (INIS)

    Ofori-Boateng, Cynthia; Keat, Teong Lee; JitKang, Lim

    2012-01-01

    The exergy analyses performed in this study are based on three thermodynamic performance parameters namely exergy destruction, exergy efficiency and thermodynamic improvement potentials. After mathematical analysis with Aspen Plus software, the results showed that 64% and 44% of the total exergy content of the input resources into microalgal methyl ester (MME) and jatropha methyl ester (JME) production plants were destroyed respectively for 1 ton of biodiesel produced. This implies that only 36% and 56% (for MME and JME production plants respectively) useful energy in the products is available to do work. The highest and lowest exergy destructions were recorded in the oil extraction units (38% and 39% of the total exergy destroyed for MME and JME plants respectively) and transesterification units (5% and 2% of total exergy destroyed for MME and JME plants respectively) respectively for 1 ton biodiesel produced. Since sustainable biodiesel production depends on cultivation of feedstock, oil extraction and transesterification processes, exergy analysis which is carried out on only the transesterification unit cannot justify the thermodynamic feasibility of the whole biodiesel production plant unless a complete thermodynamic assessment has been done for the whole plant. Thus, according to this study which considers all the biodiesel production processes, MME and JME production plants are not thermodynamically feasible. - Highlights: ► 64% of exergy content of input resources into MME production plant is destroyed. ► 44% of exergy content of input resources into JME production plant is destroyed. ► Exergetic efficiencies of MME and JME production plants are far less than 1. ► Thermodynamically, MME and JME production plants are unsustainable. ► Exergy loss can be reduced by using heat integrated reactive distillation process.

  4. Minimization of local impact of energy systems through exergy analysis

    International Nuclear Information System (INIS)

    Cassetti, Gabriele; Colombo, Emanuela

    2013-01-01

    Highlights: • The model proposed aims at minimizing local impact of energy systems. • The model is meant to minimize the impact starting from system thermodynamics. • The formulation combines exergy analysis and quantitative risk analysis. • The approach of the model is dual to Thermoeconomics. - Abstract: For the acceptability of energy systems, environmental impacts are becoming more and more important. One primary way for reducing impacts related to processes is by improving efficiency of plants. A key instrument currently used to verify such improvements is exergy analysis, extended to include also the environmental externalities generated by systems. Through exergy-based analyses, it is possible indeed to evaluate the overall amount of resources consumed along all the phases of the life cycle of a system, from construction to dismantling. However, resource consumption is a dimension of the impact of a system at global level, while it may not be considered a measure of its local impact. In the paper a complementary approach named Combined Risk and Exergy Analysis (CRExA) to assess impacts from major accidents in energy systems is proposed, based on the combination of classical exergy analysis and quantitative risk analysis (QRA). Impacts considered are focused on effects on human health. The approach leads to the identification of solutions to minimize damages of major accidents by acting on the energy system design

  5. Exergy conversion in the Japanese society

    International Nuclear Information System (INIS)

    Wall, G.

    1989-01-01

    In this paper exergy concept is reviewed as a tool for resource accounting. Conversions of energy and material resources in the Japanese society are described in terms of exergy. Necessary concepts and conventions are introduced. Exergy losses in transformations of material resources and in conversions of various forms of energy are described in some detail

  6. Exergy Evaluation of Desalination Processes

    Directory of Open Access Journals (Sweden)

    Veera Gnaneswar Gude

    2018-06-01

    Full Text Available Desalination of sea or brackish water sources to provide clean water supplies has now become a feasible option around the world. Escalating global populations have caused the surge of desalination applications. Desalination processes are energy intensive which results in a significant energy portfolio and associated environmental pollution for many communities. Both electrical and heat energy required for desalination processes have been reduced significantly over the recent years. However, the energy demands are still high and are expected to grow sharply with increasing population. Desalination technologies utilize various forms of energy to produce freshwater. While the process efficiency can be reported by the first law of thermodynamic analysis, this is not a true measure of the process performance as it does not account for all losses of energy. Accordingly, the second law of thermodynamics has been more useful to evaluate the performance of desalination systems. The second law of thermodynamics (exergy analysis accounts for the available forms of energy in the process streams and energy sources with a reference environment and identifies the major losses of exergy destruction. This aids in developing efficient desalination processes by eliminating the hidden losses. This paper elaborates on exergy analysis of desalination processes to evaluate the thermodynamic efficiency of major components and process streams and identifies suitable operating conditions to minimize exergy destruction. Well-established MSF, MED, MED-TVC, RO, solar distillation, and membrane distillation technologies were discussed with case studies to illustrate the exergy performances.

  7. Thermodynamic evaluation of a kerosene pre- Fraction unit using energy and exergy analysis

    Directory of Open Access Journals (Sweden)

    Ehsan Ghasemi

    2017-09-01

    Full Text Available This work applies the method of energy and exergy analysis over first step of linear alkyl benzene (LAB production namely kerosene pre fraction plant, to determine unit energy and exergy performance and loss, besides of opportunities for improvement based on operational data. For this purpose macroscopic energy and exergy balance was developed over main equipment including electro pumps, heat exchangers, air coolers, and distillation columns. The results shows that total energy performance of plant is 92.62% by 19.76 MW energy lost, while from exergy perspective, unit performance is 78.08% by 17.92 MW exergy lost. Maximum local exergy lost occurs in the feed pre heater exchanger by 27% performance which is designed to recover energy from top product of second column, furthermore results shows that upgrading low quality energy in air coolers based on heat pump concept would protect energy and exergy emission to the environment and reduce 40% of total lost energy and 16% of total lost exergy in plant.

  8. Studies on the Exergy Transfer Law for the Irreversible Process in the Waxy Crude Oil Pipeline Transportation

    Directory of Open Access Journals (Sweden)

    Qinglin Cheng

    2018-04-01

    Full Text Available With the increasing demand of oil products in China, the energy consumption of pipeline operation will continue to rise greatly, as well as the cost of oil transportation. In the field of practical engineering, saving energy, reducing energy consumption and adapting to the international oil situation are the development trends and represent difficult problems. Based on the basic principle of non-equilibrium thermodynamics, this paper derives the field equilibrium equations of non-equilibrium thermodynamic process for pipeline transportation. To seek the bilinear form of “force” and “flow” in the non-equilibrium thermodynamics of entropy generation rate, the oil pipeline exergy balance equation and the exergy transfer pipeline dynamic equation of the irreversibility were established. The exergy balance equation was applied to energy balance evaluation system, which makes the system more perfect. The exergy flow transfer law of the waxy oil pipeline were explored deeply from the directions of dynamic exergy, pressure exergy, thermal exergy and diffusion exergy. Taking an oil pipeline as an example, the influence factors of exergy transfer coefficient and exergy flow density were analyzed separately.

  9. Exergy analysis for combined regenerative Brayton and inverse Brayton cycles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zelong; Chen, Lingen; Sun, Fengrui [College of Naval Architecture and Power, Naval University of Engineering, Wuhan 430033 (China)

    2012-07-01

    This paper presents the study of exergy analysis of combined regenerative Brayton and inverse Brayton cycles. The analytical formulae of exergy loss and exergy efficiency are derived. The largest exergy loss location is determined. By taking the maximum exergy efficiency as the objective, the choice of bottom cycle pressure ratio is optimized by detailed numerical examples, and the corresponding optimal exergy efficiency is obtained. The influences of various parameters on the exergy efficiency and other performances are analyzed by numerical calculations.

  10. Exergy analysis for combined regenerative Brayton and inverse Brayton cycles

    OpenAIRE

    Zelong Zhang, Lingen Chen, Fengrui Sun

    2012-01-01

    This paper presents the study of exergy analysis of combined regenerative Brayton and inverse Brayton cycles. The analytical formulae of exergy loss and exergy efficiency are derived. The largest exergy loss location is determined. By taking the maximum exergy efficiency as the objective, the choice of bottom cycle pressure ratio is optimized by detailed numerical examples, and the corresponding optimal exergy efficiency is obtained. The influences of various parameters on the exergy efficien...

  11. Exergy Rate Profile of Multicomponent Distillation System

    Directory of Open Access Journals (Sweden)

    Kehinde Adewale Adesina

    2016-07-01

    Full Text Available Exergy rate profiles, exergetic efficiency and irreversibility were used to examine the driving forces in multicomponent distillation system with the view to identifying feasible and efficient operating parameters. The mixture used comprised of 5% propane, 15% iso-butane, 25% nbutane, 20% iso-pentane and 35% n-pentane. Operating variables were feed temperature (-30 oC and -80 oC, pressure (800 kPa and 1200 kPa, and reflux-ratio (2 and 6. Stage-by-stage system exergy analysis was estimated. Column profiles of base case -30 oC, -80 oC, -30 oC-reflus ratio 6, -80 oC reflux ratio 6 and base case reflux ratio 6 did not crossed thus are thermodynamically feasible. Base case -30 oC-reflux ratio 2, -80 oC-reflux ratio 2, and base case-reflux ratio 2 were crossed and constricted and are infeasible. Base case results gave efficiency of 81.7% at depropanizer and 65.2% at debutanizer. Base cases sensitivity results with -30 oC, -80 oC and reflux ratio 6, efficiency range 57.40 – 70% and 65.20% - 54.90% for depropanizer and debutanizer respectively. Spitted cases gave 81.7% and 62.20% with more scatter profiles. Splitted feed base case -30 oC design gave the lowest overall system exergy loss rate of 1.12E+6 and efficiency of 95.70%. Design feasible parameters, system efficiency and irreversibility which form basis

  12. Assessment of the Turkish utility sector through energy and exergy analyses

    International Nuclear Information System (INIS)

    Utlu, Zafer; Hepbasli, Arif

    2007-01-01

    The present study deals with evaluating the utility sector in terms of energetic and exergetic aspects. In this regard, energy and exergy utilization efficiencies in the Turkish utility sector over a wide range of period from 1990 to 2004 are assessed in this study. Energy and exergy analyses are performed for eight power plant modes, while they are based on the actual data over the period studied. Sectoral energy and exergy analyses are conducted to study the variations of energy and exergy efficiencies for each power plants throughout the years, and overall energy and exergy efficiencies are compared for these power plants. The energy utilization efficiencies for the overall Turkish utility sector range from 32.64% to 45.69%, while the exergy utilization efficiencies vary from 32.20% to 46.81% in the analyzed years. Exergetic improvement potential for this sector are also determined to be 332 PJ in 2004. It may be concluded that the methodology used in this study is practical and useful for analyzing sectoral and subsectoral energy and exergy utilization to determine how efficient energy and exergy are used in the sector studied. It is also expected that the results of this study will be helpful in developing highly applicable and productive planning for energy policies

  13. Energy and exergy analyses of medium temperature latent heat thermal storage with high porosity metal matrix

    International Nuclear Information System (INIS)

    Kumar, Ashish; Saha, Sandip K.

    2016-01-01

    Graphical abstract: I. Metal matrix is used as the thermal conductivity enhancers (TCE) in PCM-based TES. II. Time evolution second law analysis is evaluated for different porosities and pore diameters. III. Reduction in fluctuation in HTF temperature is significantly affected by the change in porosity (ε) shown in figure. IV. Maximum energy and exergy efficiencies are obtained for porosity of 0.85. V. Effect of pore diameter on first law and second law efficiencies is found to be marginal. - Abstract: Thermal energy storage system in a concentrating solar plant (CSP) reduces the gap between energy demand and supply caused by the intermittent behaviour of solar radiation. In this paper, detailed exergy and energy analyses of shell and tube type latent heat thermal storage system (LHTES) for medium temperature solar thermal power plant (∼200 °C) are performed to estimate the net useful energy during the charging and discharging period in a cycle. A commercial-grade organic phase change material (PCM) is stored inside the annular space of the shell and the heat transfer fluid (HTF) flows through the tubes. Thermal conductivity enhancer (TCE) in the form of metal matrix is embedded in PCM to augment heat transfer. A numerical model is developed to investigate the fluid flow and heat transfer characteristics using the momentum equation and the two-temperature non-equilibrium energy equation coupled with the enthalpy method to account for phase change in PCM. The effects of storage material, porosity and pore-diameter on the net useful energy that can be stored and released during a cycle, are studied. It is found that the first law efficiency of sensible heat storage system is less compared to LHTES. With the decrease in porosity, the first law and second law efficiencies of LHTES increase for both the charging and discharging period. There is no significant variation in energy and exergy efficiencies with the change in pore-diameter of the metal matrix.

  14. Exergy method technical and ecological applications

    CERN Document Server

    Szargut, J

    2005-01-01

    The exergy method makes it possible to detect and quantify the possibilities of improving thermal and chemical processes and systems. The introduction of the concept ""thermo-ecological cost"" (cumulative consumption of non-renewable natural exergy resources) generated large application possibilities of exergy in ecology. This book contains a short presentation on the basic principles of exergy analysis and discusses new achievements in the field over the last 15 years. One of the most important issues considered by the distinguished author is the economy of non-renewable natural exergy.

  15. On the definition of exergy efficiencies for petroleum systems: Application to offshore oil and gas processing

    DEFF Research Database (Denmark)

    Nguyen, Tuong-Van; Voldsund, Mari; Elmegaard, Brian

    2014-01-01

    Exergy-based efficiencies are measures of the thermodynamic perfection of systems and processes. A meaningful formulation of these performance criteria for petroleum systems is difficult because of (i) the high chemical exergy of hydrocarbons, (ii) the large variety of chemical components, and (iii....... They showed a low sensitivity to performance improvements, gave inconsistent results, or favoured facilities operating under certain con-ditions. We suggest an alternative formulation, called the component-by-component exergy efficiency, which builds on the decomposition of the exergy ows at the level...... the highest performance (29.6%). A more realistic measure of the technical potential for improving these systems can be carried out by splitting further the exergy destruction into its avoidable and unavoidable parts....

  16. Energy system analysis of a pilot net-zero exergy district

    International Nuclear Information System (INIS)

    Kılkış, Şiir

    2014-01-01

    Highlights: • Östra Sala backe is analyzed as a pilot district for the net-zero exergy target. • An analysis tool is developed for proposing an energy system for Östra Sala backe. • A total of 8 different measures are included and integrated in the energy system. • The exergy produced on-site is 49.7 GW h, the annual exergy consumed is 54.3 GW h. • The average value of the level of exergy match in the supply and demand is 0.84. - Abstract: The Rational Exergy Management Model (REMM) provides an analytical model to curb primary energy spending and CO 2 emissions by means of considering the level of match between the grade/quality of energy resources (exergy) on the supply and demand sides. This model is useful for developing forward-looking concepts with an energy systems perspective. One concept is net-zero exergy districts, which produce as much energy at the same grade or quality as consumed on an annual basis. This paper analyzes the district of Östra Sala backe in Uppsala Municipality in Sweden as a pilot, near net-zero exergy district. The district is planned to host 20,000 people at the end of four phases. The measures that are considered include an extension of the combined heat and power based district heating and cooling network, heat pumps driven on renewable energy, district heating driven white goods, smart home automation, efficient lighting, and bioelectricity driven public transport. A REMM Analysis Tool for net-zero exergy districts is developed and used to analyze 5 scenarios based on a Net-Zero Exergy District Option Index. According to the results, a pilot concept for the first phase of the project is proposed. This integrates a mix of 8 measures considering an annual electricity load of 46.0 GW h e and annual thermal load of 67.0 GW h t . The exergy that is produced on-site with renewable energy sources is 49.7 GW h and the annual exergy consumed is 54.3 GW h. The average value of the level of match between the demand and supply of

  17. Use of process steam in vapor absorption refrigeration system for cooling and heating applications: An exergy analysis

    Directory of Open Access Journals (Sweden)

    S. Anand

    2016-12-01

    Full Text Available The exponential increase in cost of conventional fuels shifts the interest toward the use of alternative as well waste energy sources for the operation of refrigeration and air-conditioning units. The present study therefore analyzes the performance of a process steam-operated vapor absorption system for cooling and heating applications using ammonia and water as working fluids based on first and second laws of thermodynamics. A mathematical model has been developed based on exergy analysis to investigate the performance of the system. The different performance parameters such as coefficient of performance (COP and exergetic efficiency of absorption system for cooling and heating applications are also calculated under different operating conditions. The results obtained show that cooling and heating COP along with second law efficiency (exergy efficiency increases with the heat source temperature at constant evaporator, condenser, and absorber temperature. Also, COP as well as exergy efficiency increases with an increase in the evaporator temperature at constant generator, condenser, and absorber temperature. The effect of ambient temperature on the exergetic efficiency for cooling and heating applications is also studied. The results obtained from the simulation studies can be used to optimize different components of the system so that the performance can be improved significantly.

  18. Exergy analysis for Generation IV nuclear plant optimization

    International Nuclear Information System (INIS)

    Gomez, A.; Azzaro-Pantel, C.; Domenech, S.; Pibouleau, L.; Latge, Ch.; Haubensack, D.; Dumaz, P.

    2010-01-01

    This paper deals with the application of the exergy concept to an energy production system involving a very high temperature reactor coupled with an innovative electricity-generating cycle. The objective is to propose a general approach to quantify exergy destruction of the involved process components, modelled by a thermodynamic simulator (Proceedings of the Conference on High Temperature Reactors, Beijing, China, 22-24 September 2004, International Atomic Agency, Vienna (Austria), HTR-2004; 1-11). The minimization of exergy destruction is then identified as the optimization criterion used in an optimization framework based on a genetic algorithm, in which the model is embedded. Finally, the approach is applied to electrical production by a Brayton-Rankine combined cycle connected to a nuclear reactor. Some typical results are presented. The perspectives of this work including the cogeneration of hydrogen and electricity are highlighted. (authors)

  19. Exergy analysis for Generation IV nuclear plant optimization

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, A.; Azzaro-Pantel, C.; Domenech, S.; Pibouleau, L. [Univ Toulouse, Lab Genie Chim, CNRS, UMR 5503, F-31700 Toulouse 1 (France); Latge, Ch. [CEA Cadarache DEN DTN DIR, St Paul Les Durance, (France); Haubensack, D.; Dumaz, P. [CEA Cadarache DEN DER SESI LCSI, St Paul Les Durance (France)

    2010-07-01

    This paper deals with the application of the exergy concept to an energy production system involving a very high temperature reactor coupled with an innovative electricity-generating cycle. The objective is to propose a general approach to quantify exergy destruction of the involved process components, modelled by a thermodynamic simulator (Proceedings of the Conference on High Temperature Reactors, Beijing, China, 22-24 September 2004, International Atomic Agency, Vienna (Austria), HTR-2004; 1-11). The minimization of exergy destruction is then identified as the optimization criterion used in an optimization framework based on a genetic algorithm, in which the model is embedded. Finally, the approach is applied to electrical production by a Brayton-Rankine combined cycle connected to a nuclear reactor. Some typical results are presented. The perspectives of this work including the cogeneration of hydrogen and electricity are highlighted. (authors)

  20. Systems Engineering in Terms of Exergy

    Directory of Open Access Journals (Sweden)

    José A. Camberos

    2009-01-01

    Full Text Available We address the design of a flight vehicle from the viewpoint of a system of systems and we discuss the integration of the individual technical disciplines. Then a conceptual fundamental methodology and tools required for the analysis, design, and optimization of aerospace vehicles in terms of the efficient use of on-board energy are discussed. This suggests changing the design paradigm to the optimization of a system of energy systems. We propose a foundation for system-level design with optimization based on minimum exergy destruction.

  1. Exergy and exergoeconomic analyses of a supercritical CO_2 cycle for a cogeneration application

    International Nuclear Information System (INIS)

    Wang, Xurong; Yang, Yi; Zheng, Ya; Dai, Yiping

    2017-01-01

    Detailed exergy and exergoeconomic analyses are performed for a combined cogeneration cycle in which the waste heat from a recompression supercritical CO_2 Brayton cycle (sCO_2) is recovered by a transcritical CO_2 cycle (tCO_2) for generating electricity. Thermodynamic and exergoeconomic models are developed on the basis of mass and energy conservations, exergy balance and exergy cost equations. Parametric investigations are then conducted to evaluate the influence of key decision variables on the sCO_2/tCO_2 performance. Finally, the combined cycle is optimized from the viewpoint of exergoeconomics. It is found that, combining the sCO_2 with a tCO_2 cycle not only enhances the energy and exergy efficiencies of the sCO_2, but also improves the cycle exergoeconomic performance. The results show that the most exergy destruction rate takes place in the reactor, and the components of the tCO_2 bottoming cycle have less exergy destruction. When the optimization is conducted based on the exergoeconomics, the overall exergoeconomic factor, the total cost rate and the exergy destruction cost rate are 53.52%, 11243.15 $/h and 5225.17 $/h, respectively. The optimization study reveals that an increase in reactor outlet temperature leads to a decrease in total cost rate and total exergy destruction cost rate of the system. - Highlights: • Exergy and exergoeconomic analyses of a combined sCO_2/tCO_2 cycle were performed. • Exergoeconomic optimization of the sCO_2/tCO_2 cycle was presented. • The reactor had the highest exergy loss among sCO_2/tCO_2 cycle components. • The overall exergoeconomic factor was up to 53.5% for the optimum case.

  2. Ecological Economic Evaluation Based on Emergy as Embodied Cosmic Exergy: A Historical Study for the Beijing Urban Ecosystem 1978–2004

    Directory of Open Access Journals (Sweden)

    Jiang Mei Ming

    2010-06-01

    Full Text Available For ecological economic evaluation based on the unified biophysical matrix this research illustrates an updated emergy synthesis in terms of embodied cosmic exergy instead of embodied solar energy, which successes the foundation of systems ecological theory but changes the starting point for the estimation from simply the sun to the cosmos. According to the modified definition implicating explicit scarcity and strict additivity based on the fundamental thermodynamics laws, the updated emergy approach overcomes the confusable and intractable deficiencies of traditional one and shows firmer theoretical basis as well as better applicability. As a case study for the regional socio-economic ecosystem, a cosmic emergy based ecological economic evaluation of the Beijing urban ecosystem during the period 1978-2004 is presented. The local and external resources supporting the concerned ecosystem are accounted and analyzed in a common unit, i.e., cosmic Joule, according to which a series of indicators are applied to reveal its evolutional characteristics through five aspects as emergy structure, emergy intensity, emergy welfare, environmental impacts, and degree of exploitation and economic efficiency. During the analyzed period, the major emergy source sustaining the operation of the ecosystem had changed from the renewable resources exploited locally to the nonrenewable resources purchased from outside. Emergy intensity for the Beijing urban ecosystem kept rising owing to the continuous investment of resources, which not only improved the living standard but also intensified the environmental pressure. Moreover, the increase of exploitation degree was accompanied with the decline of economic efficiency, while the rising emergy investment ratio implicates that Beijing was at the risks of resources shortage and high dependence on external resources

  3. Resource recovery from residual household waste: An application of exergy flow analysis and exergetic life cycle assessment.

    Science.gov (United States)

    Laner, David; Rechberger, Helmut; De Soete, Wouter; De Meester, Steven; Astrup, Thomas F

    2015-12-01

    Exergy is based on the Second Law of thermodynamics and can be used to express physical and chemical potential and provides a unified measure for resource accounting. In this study, exergy analysis was applied to four residual household waste management scenarios with focus on the achieved resource recovery efficiencies. The calculated exergy efficiencies were used to compare the scenarios and to evaluate the applicability of exergy-based measures for expressing resource quality and for optimizing resource recovery. Exergy efficiencies were determined based on two approaches: (i) exergy flow analysis of the waste treatment system under investigation and (ii) exergetic life cycle assessment (LCA) using the Cumulative Exergy Extraction from the Natural Environment (CEENE) as a method for resource accounting. Scenario efficiencies of around 17-27% were found based on the exergy flow analysis (higher efficiencies were associated with high levels of material recycling), while the scenario efficiencies based on the exergetic LCA lay in a narrow range around 14%. Metal recovery was beneficial in both types of analyses, but had more influence on the overall efficiency in the exergetic LCA approach, as avoided burdens associated with primary metal production were much more important than the exergy content of the recovered metals. On the other hand, plastic recovery was highly beneficial in the exergy flow analysis, but rather insignificant in exergetic LCA. The two approaches thereby offered different quantitative results as well as conclusions regarding material recovery. With respect to resource quality, the main challenge for the exergy flow analysis is the use of exergy content and exergy losses as a proxy for resource quality and resource losses, as exergy content is not per se correlated with the functionality of a material. In addition, the definition of appropriate waste system boundaries is critical for the exergy efficiencies derived from the flow analysis, as it

  4. Upgrading versus reforming: an energy and exergy analysis of two Solid Oxide Fuel Cell-based systems for a convenient biogas-to-electricity conversion

    International Nuclear Information System (INIS)

    Baldinelli, A.; Barelli, L.; Bidini, G.

    2017-01-01

    Highlights: • Biogas-to-electricity conversion through Solid Oxide Fuel Cell is investigated. • Two solutions are compared for biogas-to-electricity conversion. • Direct feeding by partially upgraded biogas meets with fuel cell long operation. • Best energy and exergy performances are obtained with an innovative system-design. • A sensitivity analysis on the process parameters determines its convenience margin. - Abstract: Aiming at designing biogas-to-electricity advanced systems, Solid Oxide Fuel Cells are promising candidates. They benefit from scalability on plant sizes that suit anaerobic digesters potentialities. For biogas-Solid Oxide Fuel Cells applications, the implementation of an external pre-reformer is usually considered. However, the possibility to perform direct fuel feeding to the Solid Oxide Fuel Cell offers new opportunities towards the realization of lean systems, which are competitive especially on small-scale installations (i.e. on-farm biogas-to-electricity conversion). In this frame, scientific literature is rather poor and, to cover this gap, system simulations are called for two reasons: first, to demonstrate the potential efficiency gain of new concepts; second, to provide a meaningful support for long-term experimental investigation on Solid Oxide Fuel Cells operated upon direct feeding of unreformed biogas. For that, the current study compares two system designs for biogas utilization into Solid Oxide Fuel Cells. The conventional one realizes biogas steam reforming prior the fuel cell, while the novel concept is based on direct feeding of partially upgraded biogas by means of carbon dioxide-separation membranes. As main outcome of the study, the system equipped with carbon dioxide-separation membranes achieves better performances than its conventional competitor does, scoring 51.1% energy efficiency and 52.3% exergy efficiency (compared to 37.2% and 38.6% respectively exhibited by the reformer-based system). Because of the lack

  5. Modeling of chemical exergy of agricultural biomass using improved general regression neural network

    International Nuclear Information System (INIS)

    Huang, Y.W.; Chen, M.Q.; Li, Y.; Guo, J.

    2016-01-01

    A comprehensive evaluation for energy potential contained in agricultural biomass was a vital step for energy utilization of agricultural biomass. The chemical exergy of typical agricultural biomass was evaluated based on the second law of thermodynamics. The chemical exergy was significantly influenced by C and O elements rather than H element. The standard entropy of the samples also was examined based on their element compositions. Two predicted models of the chemical exergy were developed, which referred to a general regression neural network model based upon the element composition, and a linear model based upon the high heat value. An auto-refinement algorithm was firstly developed to improve the performance of regression neural network model. The developed general regression neural network model with K-fold cross-validation had a better ability for predicting the chemical exergy than the linear model, which had lower predicted errors (±1.5%). - Highlights: • Chemical exergies of agricultural biomass were evaluated based upon fifty samples. • Values for the standard entropy of agricultural biomass samples were calculated. • A linear relationship between chemical exergy and HHV of samples was detected. • An improved GRNN prediction model for the chemical exergy of biomass was developed.

  6. Avoidable and unavoidable exergy destruction and exergoeconomic evaluation of the thermal processes in a real industrial plant

    Directory of Open Access Journals (Sweden)

    Vučković Goran D.

    2012-01-01

    Full Text Available Exergy analysis is a universal method for evaluating the rational use of energy. It can be applied to any kind of energy conversion system or chemical process. An exergy analysis identifies the location, the magnitude and the causes of thermodynamic inefficiencies and enhances understanding of the energy conversion processes in complex systems. Conventional exergy analyses pinpoint components and processes with high irreversibility. To overcome the limitations of the conventional analyses and to increase our knowledge about a plant, advanced exergy-based analyses are developed. These analyses provide additional information about component interactions and reveal the real potential for improvement of each component constituting a system, as well as of the overall system. In this paper, a real industrial plant is analyzed using both conventional and advanced exergy analyses, and exergoeconomic evaluation. Some of the exergy destruction in the plant components is unavoidable and constrained by technological, physical and economic limitations. Calculations related to the total avoidable exergy destruction caused by each component of the plant supplement the outcome of the conventional exergy analysis. Based on the all-reaching analysis, by improving the boiler operation (elimination of approximately 1 MW of avoidable exergy destruction in the steam boiler the greatest improvement in the efficiency of the overall system can be achieved.

  7. Diagnosis of an alternative ammonia process technology to reduce exergy losses

    International Nuclear Information System (INIS)

    Ghannadzadeh, Ali; Sadeqzadeh, Majid

    2016-01-01

    Highlights: • Pinpointed non-efficient units by visualized exergetic ammonia process flowsheets. • Recommended ways towards sustainable ammonia productions based on exergy-loss sources. • Demonstrated applicability of the exergetic solutions panel on an ammonia process. - Abstract: Ammonia production through more efficient technologies can be achieved using exergy analysis. Ammonia production is one of the most important but also one of most energy consuming processes in the chemical industry. Based on a panel of solutions previously developed, this study helps to identify potential areas of improvement using an exergy analysis that covers all aspects of conventional ammonia synthesis and separation. The total internal and external exergy losses are calculated as 3,152 and 6,364 kJ/kg, respectively. The process is then divided into five main functional blocks based on their exergy losses. The reforming block contains the largest exergy loss (3,098 kJ/kg) and thus the largest potential for improvement including preheating cold feed through an economizer, developing technology towards isobaric mixing, and pressure drop reduction in the secondary reformer as the main contributors to the irreversibility (1,302 kJ/kg) in this block. The second largest exergy loss resides in the ammonia synthesis block (3,075 kJ/kg) where solutions such as reduced temperature rise across the compressor, proper compressor isolation, reducing undesired components such as argon in the reactor feed, and using lower temperatures for reactor outlet streams, are proposed to decrease the exergy losses. Throttling process in the syngas separator is the key contributing mechanism for the irreversibility (1,635 kJ/kg exergy losses) in the gas upgrading block. The exergy losses in the residual ammonia removal block (833 kJ/kg exergy losses) are mainly due to the stripper and the absorber column where a modified column design might be helpful. The highest exergy loss in the preheating block

  8. Energy Rebound as a Potential Threat to a Low-Carbon Future: Findings from a New Exergy-Based National-Level Rebound Approach

    Directory of Open Access Journals (Sweden)

    Paul E. Brockway

    2017-01-01

    Full Text Available 150 years ago, Stanley Jevons introduced the concept of energy rebound: that anticipated energy efficiency savings may be “taken back” by behavioural responses. This is an important issue today because, if energy rebound is significant, this would hamper the effectiveness of energy efficiency policies aimed at reducing energy use and associated carbon emissions. However, empirical studies which estimate national energy rebound are rare and, perhaps as a result, rebound is largely ignored in energy-economy models and associated policy. A significant difficulty lies in the components of energy rebound assessed in empirical studies: most examine direct and indirect rebound in the static economy, excluding potentially significant rebound of the longer term structural response of the national economy. In response, we develop a novel exergy-based approach to estimate national energy rebound for the UK and US (1980–2010 and China (1981–2010. Exergy—as “available energy”—allows a consistent, thermodynamic-based metric for national-level energy efficiency. We find large energy rebound in China, suggesting that improvements in China’s energy efficiency may be associated with increased energy consumption (“backfire”. Conversely, we find much lower (partial energy rebound for the case of the UK and US. These findings support the hypothesis that producer-sided economies (such as China may exhibit large energy rebound, reducing the effectiveness of energy efficiency, unless other policy measures (e.g., carbon taxes are implemented. It also raises the prospect we need to deploy renewable energy sources faster than currently planned, if (due to rebound energy efficiency policies cannot deliver the scale of energy reduction envisaged to meet climate targets.

  9. Fluid discrimination based on rock physics templates

    International Nuclear Information System (INIS)

    Liu, Qian; Yin, Xingyao; Li, Chao

    2015-01-01

    Reservoir fluid discrimination is an indispensable part of seismic exploration. Reliable fluid discrimination helps to decrease the risk of exploration and to increase the success ratio of drilling. There are many kinds of fluid indicators that are used in fluid discriminations, most of which are single indicators. But single indicators do not always work well under complicated reservoir conditions. Therefore, combined fluid indicators are needed to increase accuracies of discriminations. In this paper, we have proposed an alternative strategy for the combination of fluid indicators. An alternative fluid indicator, the rock physics template-based indicator (RPTI) has been derived to combine the advantages of two single indicators. The RPTI is more sensitive to the contents of fluid than traditional indicators. The combination is implemented based on the characteristic of the fluid trend in the rock physics template, which means few subjective factors are involved. We also propose an inversion method to assure the accuracy of the RPTI input data. The RPTI profile is an intuitionistic interpretation of fluid content. Real data tests demonstrate the applicability and validity. (paper)

  10. Evolution of the decrease in mineral exergy throughout the 20th century. The case of copper in the US

    International Nuclear Information System (INIS)

    Valero, Alicia; Valero, Antonio; Arauzo, Inmaculada

    2008-01-01

    A mineral deposit is a natural resource whose exergy can be calculated from a defined reference environment (RE). This RE can be compared to a thermodynamically dead planet, where all materials have reacted, dispersed and mixed. Like any substance, a mine is characterized by its quantity, chemical composition and concentration (ore grade). The mine's exergy measures the minimum (reversible) energy to extract and concentrate the materials from the RE to the conditions in the mine. And the mine's exergy replacement cost accounts for the actual exergy required to accomplish this, with available technologies. The exergy assessment of the natural resource wealth of the Earth defined from a RE is named as exergoecology. The aim of this paper is to prove the usefulness of these two indicators for assessing the degradation of mineral deposits over history. As an example, the exergy decrease of US copper mines due to copper extraction throughout the 20th century has been determined. The results indicate that the exergy decrease was 65.4 Mtoe, while the exergy replacement cost 889.9 Mtoe. During the past century, the US extracted the equivalent of 2.5 and 1.2 times of its current national exergy reserves and base reserve of copper, respectively

  11. Energy and exergy assessments for an enhanced use of energy in buildings

    Science.gov (United States)

    Goncalves, Pedro Manuel Ferreira

    supply options are proposed and assessed as primary energy demand and exergy efficiency, showing it as a possible benchmarking method for future legislative frameworks regarding the energy performance assessment of buildings. Case study IV proposes a set of complementary indicators for comparing cogeneration and separate heat and electricity production systems. It aims to identify the advantages of exergy analysis relative to energy analysis, giving particular examples where these advantages are significant. The results demonstrate that exergy analysis can reveal meaningful information that might not be accessible using a conventional energy analysis approach, which is particularly evident when cogeneration and separated systems provide heat at very different temperatures. Case study V follows the exergy analysis method to evaluate the energy and exergy performance of a desiccant cooling system, aiming to assess and locate irreversibilities sources. The results reveal that natural gas boiler is the most inefficient component of the plant in question, followed by the chiller and heating coil. A set of alternative heating supply options for desiccant wheel regeneration is proposed, showing that, while some renewables may effectively reduce the primary energy demand of the plant, although this may not correspond to the optimum level of exergy efficiency. The thermal and chemical exergy components of moist air are also evaluated, as well as, the influence of outdoor environmental conditions on the energy/exergy performance of the plant. This research provides knowledge that is essential for the future development of complementary energy- and exergy-based indicators, helping to improve the current methodologies on performance assessments of buildings, cogeneration and desiccant cooling systems. The significance of exergy analysis is demonstrated for different types of buildings, which may be located in different climates (reference states) and be supplied by different types

  12. FORMATE-BASED FLUIDS: FORMULATION AND APPLICATION

    Directory of Open Access Journals (Sweden)

    Nediljka Gaurina-Međimurec

    2008-12-01

    Full Text Available Formate-based fluids has been successfully used in over hunders HPHT well operations since they introduced in field practice. They have many advantages when compared with conventional HPHT drilling and completion fluids such as: minimal formation damage, maintenance of additve properties at high temperatures, reduced hydraulic flow resistance, low potential for differential sticking, naturally lubricating, very low corrosion rates, biodegradable and pose little risk to the environment etc. Formate-based fluids can be applied during deep slim hole drilling, shale drilling, reservoir drilling, salt and gas hydrate formations drilling. The laboratory research was carried out to evaluate the rheological behavior of formate-based fluids as a function of temperature. Formate-based fluids were formulated using potassium formate brine, xanthan polymer, PAC, starch and calcium carbonate. Experimental results show that potassium formate improves the thermal stability of polymers.

  13. Energy, exergy, and economic analysis of a geothermal power plant

    Directory of Open Access Journals (Sweden)

    Hamid Kazemi

    2018-04-01

    Full Text Available The current study aimed at designing a geothermal power plant in the Nonal area in Damavand district for simultaneous generation of thermal energy the electric power in the network of Damavand City and a part of Tehran province, the organic working fluid for the above cycle is R245fa which is a non-flammable fluid of dry type. The values of energy efficiency, exergy, the net rate of entropy change, and the specific output power were calculated as 18.2%, 21.3%, 172.97 kW/K, and 31.43 kJ/kg, respectively. The cost of drilling a well, as well as designing and construction of Damavand’s geothermal power plant, were calculated to be 4.2 and 521.5 million (USD, respectively. Also, the cost per generation of each kW/h of power in Damavand power plant was 17 cents. The estimated payback time is calculated as 15 years. The analysis of the cycle in different months of the year showed that exergy efficiency has little change. The only significant effect of temperature changes was on the exergy efficiency as approximately a change of 2% can be seen during a year.

  14. Energy and exergy analyses of an ice-on-coil thermal energy storage system

    International Nuclear Information System (INIS)

    Ezan, Mehmet Akif; Erek, Aytunç; Dincer, Ibrahim

    2011-01-01

    In this study, energy and exergy analyses are carried out for the charging period of an ice-on-coil thermal energy storage system. The present model is developed using a thermal resistance network technique. First, the time-dependent variations of the predicted total stored energy, mass of ice, and outlet temperature of the heat transfer fluid from a storage tank are compared with the experimental data. Afterward, performance of an ice-on-coil type latent heat thermal energy storage system is investigated for several working and design parameters. The results of a comparative study are presented in terms of the variations of the heat transfer rate, total stored energy, dimensionless energetic/exergetic effectiveness and energy/exergy efficiency. The results indicate that working and design parameters of the ice-on-coil thermal storage tank should be determined by considering both energetic and exergetic behavior of the system. For the current parameters, storage capacity and energy efficiency of the system increases with decreasing the inlet temperature of the heat transfer fluid and increasing the length of the tube. Besides, the exergy efficiency increases with increasing the inlet temperature of the heat transfer fluid and increasing the length of the tube. -- Highlights: ► A comprehensive study on energy and exergy analyses of an ice-on-coil TES system. ► Determination of irreversibilities and their potential sources. ► Evaluation of both energy and exergy efficiencies and their comparisons.

  15. Energy and exergy assessments of a perlite expansion furnace in a plaster plant

    International Nuclear Information System (INIS)

    Gürtürk, Mert; Oztop, Hakan F.; Hepbaslı, Arif

    2013-01-01

    Highlights: • Importance of energy efficiency on perlite process is discussed. • Effects of perlite production on 3E, namely, energy, environment and economics is presented. • The system must be replaced with the developed technology and the return of the investment would be less than 18 months. - Abstract: In this study, energy and exergy assessments of a perlite expansion furnace in a plaster factory are performed. Chemical properties of the perlite and its application areas are described. Energy and exergy relations according to the First and Second Law of Thermodynamics are derived. Energy and exergy efficiencies, losses and exergy destructions are calculated based on the measurements obtained from the system. Evaluations of environmental impact, energy management and economic are finally generalized according to the obtained results. Energy and exergy efficiencies of the furnace are determined to be 66% and 26%, respectively. Reference temperature effects on exergy efficiency, destruction and sustainability index are also presented. The results showed that the furnace has not been well designed in terms of thermal aspects due to high energy and exergy losses and the manufacturer producing the perlite expanded should establish an energy management structure

  16. Exergy costing for energy saving in combined heating and cooling applications

    DEFF Research Database (Denmark)

    Nguyen, Chan; Veje, Christian T.; Willatzen, Morten

    2014-01-01

    . In the first method, referred to as energy costing, a conventional thermoeconomic analysis is used. Here the ammonia heat pump is subject to a thermodynamic analysis with mass and energy balance equations. In the second method referred to as exergy costing, an exergy based economic analysis is used, where...... exergy balance equations are used in conjunction with mass and energy balance equations. In both costing methods the thermodynamic analysis is followed by an economic analysis which includes investment and operating costs. For both methods the unit costs of heating and cooling are found and compared...

  17. Exergy, Energy, and Dynamic Parameter Analysis of Indigenously Developed Low-Concentration Photovoltaic System

    OpenAIRE

    Pankaj Yadav; Brijesh Tripathi; Manoj Kumar

    2013-01-01

    Piecewise linear parabolic trough collector (PLPTC) is designed and developed to concentrate solar radiation on monocrystalline silicon based photovoltaic module. A theoretical model is used to perform electrical energy and exergy analysis of low-concentration photovoltaic (LCPV) system working under actual test conditions (ATC). The exergy efficiency of LCPV system is in the range from 5.1% to 4.82% with increasing rate of input exergy rate from 30.81 W to 96.12 W, when conce...

  18. Application of exergy analysis to the thermodynamical study of operation cycles of diesel engines

    Energy Technology Data Exchange (ETDEWEB)

    Zellat, M

    1987-01-01

    To simulate the operation cycle of a diesel engine a general methodology is proposed, called as exergy theory, based on the simultaneous application of the first and second principles of thermodynamics. This analysis accounts for the exergy losses in function of what can be recovered from the second principle and give a more fruitful representation than the pure energy analysis which takes into account only the first principle. The concept of a recovery power turbine RPT, linked to the driving shaft and declutchable is described. The yield increase in nominal power and at half-charge when the RPT is disconnected, is explained by exergy analysis.

  19. Heat integration options based on pinch and exergy analyses of a thermosolar and heat pump in a fish tinning industrial process

    International Nuclear Information System (INIS)

    Quijera, José Antonio; García, Araceli; Alriols, María González; Labidi, Jalel

    2013-01-01

    Thermosolar technology is being inserted gradually in industrial activities. In order to reach high energy efficiency, thermosolar can be linked to heat pump technology, combining more efficient conventional and renewable energy support for processes. Their integration in complex processes can be improved systematically through well established analytical tools, like pinch and exergy analyses. This work presents a methodological procedure for the analysis of different options of heat integration of a solar thermal and heat pump technologies in a tuna fish tinning process. The plant is located in a climatic zone where diffuse irradiation contributes more energy to the process than beam irradiation does. Pinch and exergy analyses are applied in the context of a low and middle temperatures, where the process demands big amounts of hot water and middle pressure steam. In order to recover internal heat, pinch analysis allows to understand the complexity of the heat exchange network of the process and to define thermal tendency objectives for energy optimization. Exergy analysis quantifies the variation that the quality of energy undergoes while it is used in the process according to the different way of integration. Both analytical tools, in combination with economical variables, provide a powerful methodological procedure finding the most favourable heat integration and, by this, they help in the technological decision making and in the design phase. - Highlights: ► Integration of solar thermal energy in batch canning process was assessed. ► Pinch and exergy analyses were used to determine the optimal energy supply configuration. ► Combination of heat pump and solar thermal energy improves the energy efficiency and reduces fossil fuel consumption

  20. Exergy. Concept, challenges and usages for industry

    International Nuclear Information System (INIS)

    2013-04-01

    The increasing pressure on natural resources makes reduction of energy consumption a critical stake. The exergy concept offers a global, standard and rigorous framework to energy systems analysis, and as such, contributes to tackle the energy challenge. ENEA has released a publication that popularizes the exergy concept, explains its application within the energy efficiency field, and highlights its value for industrial actors

  1. Resource recovery from residual household waste: An application of exergy flow analysis and exergetic life cycle assessment

    DEFF Research Database (Denmark)

    Laner, David; Rechberger, Helmut; De Soete, Wouter

    2015-01-01

    Exergy is based on the Second Law of thermodynamics and can be used to express physical and chemical potential and provides a unified measure for resource accounting. In this study, exergy analysis was applied to four residual household waste management scenarios with focus on the achieved resource...... of the waste treatment system under investigation and (ii) exergetic life cycle assessment (LCA) using the Cumulative Exergy Extraction from the Natural Environment (CEENE) as a method for resource accounting. Scenario efficiencies of around 17-27% were found based on the exergy flow analysis (higher...... with the functionality of a material. In addition, the definition of appropriate waste system boundaries is critical for the exergy efficiencies derived from the flow analysis, as it is constrained by limited information available about the composition of flows in the system as well as about secondary production...

  2. Clay-based geothermal drilling fluids

    Energy Technology Data Exchange (ETDEWEB)

    Guven, N.; Carney, L.L.; Lee, L.J.; Bernhard, R.P.

    1982-11-01

    The rheological properties of fluids based on fibrous clays such as sepiolite and attapulgite have been systematically examined under conditions similar to those of geothermal wells, i.e. at elevated temperatures and pressures in environments with concentrated brines. Attapulgite- and sepiolite-based fluids have been autoclaved at temperatures in the range from 70 to 800/sup 0/F with the addition of chlorides and hydroxides of Na, K, Ca, and Mg. The rheological properties (apparent and plastic viscosity, fluid loss, gel strength, yield point, and cake thickness) of the autoclaved fluids have been studied and correlated with the chemical and physical changes that occur in the clay minerals during the autoclaving process.

  3. Regional and global exergy and energy efficiencies

    Energy Technology Data Exchange (ETDEWEB)

    Nakicenovic, N; Kurz, R [International Inst. for Applied Systems Analysis, Laxenburg (Austria). Environmentally Compatible Energy Strategies (Ecuador) Project; Gilli, P V [Graz Univ. of Technology (Austria)

    1996-03-01

    We present estimates of global energy efficiency by applying second-law (exergy) analysis to regional and global energy balances. We use a uniform analysis of national and regional energy balances and aggregate these balances first for three main economic regions and subsequently into world totals. The procedure involves assessment of energy and exergy efficiencies at each step of energy conversion, from primary exergy to final and useful exergy. Ideally, the analysis should be extended to include actual delivered energy services; unfortunately, data are scarce and only rough estimates can be given for this last stage of energy conversion. The overall result is that the current global primary to useful exergy efficiency is about one-tenth of the theoretical maximum and the service efficiency is even lower. (Author)

  4. Application of the Stirling engine driven with cryogenic exergy of LNG (liquefied natural gas) for the production of electricity

    International Nuclear Information System (INIS)

    Szczygieł, Ireneusz; Stanek, Wojciech; Szargut, Jan

    2016-01-01

    LNG (liquefied natural gas) delivered by means of sea-ships is pressurized and then regasified before its introduction to the system of pipelines. The utilization of cryogenic exergy of LNG for electricity production without combustion of any its portion is analyzed. For the conversion of LNG cryogenic exergy into electricity, the Stirling engine is proposed to be applied. The theoretical thermodynamic model of Stirling engine has been applied. This model is used to investigate the influence of pinch temperature in heat exchangers, engine compression ratio and dead volumes ratios on the thermodynamic parameters of the Stirling engine. The results of simulation represent the input data for investigations of thermodynamic performance of the proposed system. In order to evaluate the thermodynamic performance of the proposed process, an exergy analysis has been applied. The exergy efficiency and influence of design and operational parameters on exergy losses are determined for each of the proposed system configurations. The obtained results represent the background for advanced exergy-based analyses, including thermo-ecological cost. - Highlights: • Application of Stirling engine in LNG regasification. • Thermodynamic model of Stirling engine for cryogenic exergy recovery is applied. • Sensitivity analysis of operational parameters on system behaviour is applied. • Exergy analysis is conducted.

  5. Exergy analysis of encapsulation of photochromic dye by spray drying

    Science.gov (United States)

    Çay, A.; Akçakoca Kumbasar, E. P.; Morsunbul, S.

    2017-10-01

    Application of exergy analysis methodology for encapsulation of photochromic dyes by spray drying was presented. Spray drying system was investigated considering two subsystems, the heater and the dryer sections. Exergy models for each subsystem were proposed and exergy destruction rate and exergy efficiency of each subsystem and the whole system were computed. Energy and exergy efficiency of the system were calculated to be 5.28% and 3.40%, respectively. It was found that 90% of the total exergy inlet was destroyed during encapsulation by spray drying and the exergy destruction of the heater was found to be higher.

  6. Unsteady-state human-body exergy consumption rate and its relation to subjective assessment of dynamic thermal environments

    DEFF Research Database (Denmark)

    Schweiker, Marcel; Kolarik, Jakub; Dovjak, Mateja

    2016-01-01

    of the present study confirmed previously indicated trends that lowest human body exergy consumption rate is associated with thermal sensation close to neutrality. Moreover, higher acceptability was in general associated with lower human body exergy consumption rate. (C) 2016 Elsevier B.V. All rights reserved.......Few examples studied applicability of exergy analysis on human thermal comfort. These examples relate the human-body exergy consumption rate with subjectively obtained thermal sensation votes and had been based on steady-state calculation methods. However, humans are rarely exposed to steady...... between the human-body exergy consumption rate and subjective assessment of thermal environment represented by thermal sensation as well as to extend the investigation towards thermal acceptability votes. Comparison of steady-state and unsteady-state model showed that results from both models were...

  7. Reviews on Physically Based Controllable Fluid Animation

    Directory of Open Access Journals (Sweden)

    Pizzanu Kanongchaiyos

    2010-04-01

    Full Text Available In computer graphics animation, animation tools are required for fluid-like motions which are controllable by users or animator, since applying the techniques to commercial animations such as advertisement and film. Many developments have been proposed to model controllable fluid simulation with the need in realistic motion, robustness, adaptation, and support more required control model. Physically based models for different states of substances have been applied in general in order to permit animators to almost effortlessly create interesting, realistic, and sensible animation of natural phenomena such as water flow, smoke spread, etc. In this paper, we introduce the methods for simulation based on physical model and the techniques for control the flow of fluid, especially focus on particle based method. We then discuss the existing control methods within three performances; control ability, realism, and computation time. Finally, we give a brief of the current and trend of the research areas.

  8. Evolutionary synthesis of optimum light ends recovery unit with exergy analysis application

    International Nuclear Information System (INIS)

    Khalili-Garakani, Amirhossein; Ivakpour, Javad; Kasiri, Norollah

    2016-01-01

    Highlights: • Presenting an evolutionary synthesis algorithm. • Reducing configuration nominees based on exergy loss diagram of distillation columns. • Reduction of search space without decreasing the comprehensiveness and precision of the synthesis algorithm. • Rigorous simulation and optimization of sequences. - Abstract: Exergy analysis proved to be important in understanding of regions with poor energy efficiency and improve the design of distillation processes. In this study a new method based on exergy analysis is developed for the synthesis of a light ends recovery unit. The algorithm is some kinds of evolutionary one which employ total exergy loss diagrams of distillation columns for limiting the search space and reducing configuration nominees. The new method presented here for the light end separation unit, applies exergy loss diagrams as a powerful tool in locating the weak spot in the distillation columns of the Brugma sequence (as a first guess) and change the structure of the sequence step by step to achieve the best sequence. The results show that the new method could reduce the amount of calculations between 16% and 55% of the cases considered in this case study. The reduction of the search space takes place without decreasing the comprehensiveness and precision of the synthesis algorithm. Besides the amount of reduction in total annual cost and exergy loss of the optimum sequence is considerable.

  9. Energy and exergy utilization efficiencies and emission performance of Canadian transportation sector, 1990–2035

    International Nuclear Information System (INIS)

    Motasemi, F.; Afzal, Muhammad T.; Salema, Arshad Adam; Moghavvemi, M.; Shekarchian, M.; Zarifi, F.; Mohsin, R.

    2014-01-01

    Transportation sector of Canada is the second largest energy consuming sector which accounts for 30% of the total energy consumption of the country in 2009. The purpose of this work was to analyze the energy, exergy, and emission performance for four different modes of transport (road, air, rail, and marine) from the year 1990–2035. For historical period, the estimated overall energy efficiency ranges from 22.41% (1991) to 22.55% (2006) with a mean of 22.48 ± 0.07% and the overall exergy efficiency ranges from 21.61% (2001) to 21.87 (2006) with a mean of 21.74 ± 0.13%. Energy and exergy efficiencies may reach 20.95% and 20.97% in the year 2035 respectively based on the forecasted data. In comparison with other countries, we found that in the year 2000 the overall energy and exergy efficiencies for Canadian transportation sector were higher than Jordan, China, Norway, and Saudi Arabia but lower than Turkey and Malaysia. Between the year 1990–2009, the highest amount of emission produced in each subsector was: road CO 2 (80%), NO x (72%), and CO (carbon monoxide) (96%); air SO 2 (86%); rail NO x (6%) and marine NO x (7%). The road subsector produced the highest amount of emissions. - Highlights: • Energy, exergy and emission performance for Canadian transport was analyzed. • Maximum energy and exergy efficiencies were 22.55% and 21.87% in 2006 respectively. • Energy and exergy efficiencies may decrease in the year 2035. • CO 2 was the largest pollutant emitted followed by CO, NO x , and SO 2 . • Utilization of green fuels can improve exergy and emission performance

  10. Integrated assessment of exergy, energy and carbon dioxide emissions in an iron and steel industrial network

    International Nuclear Information System (INIS)

    Wu, Junnian; Wang, Ruiqi; Pu, Guangying; Qi, Hang

    2016-01-01

    Highlights: • Exergy, energy and CO_2 emissions assessment of iron and steel industrial network. • Effects of industry symbiosis measures on exergy, energy and CO_2 emissions. • Exploring the environmental impact from exergy losses. • The overall performance indexes are proposed for iron and steel industrial network. • Sinter strand and the wet quenching process have the lowest exergy efficiency. - Abstract: Intensive energy consumption and high pollution emissions in the iron and steel industry have caused problems to the energy system, in the economy, and in the environment. Iron and steel industrial network as an example of energy conservation and emissions reduction, require better analysis and assessment. The present study comprehensively assesses an iron and steel industrial network and its environmental performance with respect to exergy, energy and CO_2 emissions. The results show that the sinter strand needs to be greatly improved and the wet quenching process needs to be completely redesigned. The overall exergy efficiency and energy efficiency can be improved by adopting industrial symbiosis (IS) measures. We found that adjusting the energy structure to use renewable energy and recycling solid waste can greatly reduce CO_2 emissions. Moreover, the maximum exergy losses occurred in the blast furnace with the maximum CO_2 emissions. The iron making plant exerted a strong effect on the environment based on the equivalent CO_2 emission potentials. Many performance indicators of the entire industrial network were also examined in this work. It can be seen that integrated evaluation of energy and CO_2 emissions with exergy is necessary to help to mitigate adverse environmental impacts and more effectively fulfill the goals for energy conservation and emissions reduction.

  11. Exergy analysis of a MSF distillation plant

    International Nuclear Information System (INIS)

    Kahraman, Nafiz; Cengel, Yunus A.

    2005-01-01

    In this paper, a large MSF distillation plant in the gulf area is analyzed thermodynamically using actual plant operation data. Exergy flow rates are evaluated throughout the plant, and the exergy flow diagram is prepared. The rates of exergy destruction and their percentages are indicated on the diagram so that the locations of highest exergy destruction can easily be identified. The highest exergy destruction (77.7%) occurs within the MSF unit, as expected, and this can be reduced by increasing the number of flashing stages. The exergy destruction in the pumps and motors account for 5.3% of the total, and this also can be reduced by using high efficiency motors and pumps. The plant is determined to have a second law efficiency of just 4.2%, which is very low. This indicates that there are major opportunities in the plant to reduce exergy destruction and, thus, the amount of electric and thermal energy supplied, making the operation of the plant more cost effective

  12. Exergy and Energy Analysis of Combustion of Blended Levels of Biodiesel, Ethanol and Diesel Fuel in a DI Diesel Engine

    International Nuclear Information System (INIS)

    Khoobbakht, Golmohammad; Akram, A.; Karimi, Mahmoud; Najafi, G.

    2016-01-01

    Highlights: • Exergy analysis showed that thermal efficiency of diesel engine was 36.61%. • Energy loss and work output rates were 71.36 kW and 41.22 kW, respectively. • Exergy efficiency increased with increasing engine load and speed. • Exergy efficiency increased with increasing biodiesel and bioethanol. • 0.17 L of biodiesel, 0.08 L of ethanol in 1 L of diesel at 1900 rpm and 94% load had maximum exergy efficiency. - Abstract: In this study, the first and second laws of thermodynamics are employed to analyze the energy and energy in a four-cylinder, direct injection diesel engine using blended levels of biodiesel and ethanol in diesel fuel. Also investigated the effect of operating factors of engine load and speed as well as blended levels of biodiesel and ethanol in diesel fuel on the exergy efficiency. The experiments were designed using a statistical tool known as Design of Experiments (DoE) based on central composite rotatable design (CCRD) of response surface methodology (RSM). The resultant quadratic models of the response surface methodology were helpful to predict the response parameter (exergy efficiency) further to identify the significant interactions between the input factors on the responses. The results depicted that the exergy efficiency decreased with increasing percent by volume biodiesel and ethanol fuel. The fuel blend of 0.17 L biodiesel and 0.08 L of ethanol added to 1 L of diesel (equivalent with D80B14E6) at 1900 rpm and 94% load was realized have the most exergy efficiency. The results of energy and exergy analyses showed that 43.09% of fuel exergy was destructed and the average thermal efficiency was approximately 36.61%, and the exergetic efficiency was approximately 33.81%.

  13. Energy and exergy analyses of an integrated solar heat pump system

    International Nuclear Information System (INIS)

    Suleman, F.; Dincer, I.; Agelin-Chaab, M.

    2014-01-01

    An integrated solar and heat pump based system for industrial heating is developed in this study. The system comprises heat pump cycle for process heating water and solar energy for another industrial heating process. Comprehensive energy and exergy analyses are performed on the system. These analyses generated some compelling results as expected because of the use of green and environmentally friendly energy sources. The results show that the energy efficiency of the process is 58% while the exergy efficiency is 75%. Energetic COP of the heat pump cycle is 3.54 whereas the exergy efficiency is 42.5%. Moreover, the energetic COP of the system is 2.97 and the exergy efficiency of the system is 35.7%. In the parametric study, a different variation such as changing the temperature and pressure of the condenser also shows positive results. - Highlights: • An integrated system is analysed using renewable energy source which can be used in textile industry. • Energy losses and exergy destructions are calculated at all major components. • Energy and exergy efficiencies of all subunits, subsystems and overall system are determined. • A parametric study shows the effect of environment and operating conditions on efficiencies. • Solar energy for heating in textile industry is efficient and environmentally friendly

  14. Energy and exergy prices of various energy sources along with their CO2 equivalents

    International Nuclear Information System (INIS)

    Caliskan, Hakan; Hepbasli, Arif

    2010-01-01

    Various types of energy sources are used in the residential and industrial sectors. Choosing the type of sources is important. When an energy source is selected, its CO 2 equivalent and energy and exergy prices must be known for a sustainable future and for establishing energy policies. These prices are based on their energy values. Exergy analysis has been recently applied to a wide range of energy-related systems. Thus, obtaining the exergy values has become more meaningful for long-term planning. In this study, energy and exergy prices of various energy sources along with CO 2 equivalents are calculated and compared for residential and industrial applications in Turkey. Energy sources considered include coal, diesel oil, electricity, fuel oil, liquid petroleum gas (LPG), natural gas, heat pumps and geothermal, and their prices were obtained over a period of 18 months, from January 2008 to June 2009. For the residential and industrial sectors, minimum energy and exergy prices were found for ground source heat pumps, while maximum energy and exergy prices belong to LPG for both sectors.

  15. Cycle Design of Reverse Brayton Cryocooler for HTS Cable Cooling Using Exergy Analysis

    Science.gov (United States)

    Gupta, Sudeep Kumar; Ghosh, Parthasarathi

    2017-02-01

    The reliability and price of cryogenic refrigeration play an important role in the successful commercialization of High Temperature Superconducting (HTS) cables. For cooling HTS cable, sub-cooled liquid nitrogen (LN2) circulation system is used. One of the options to maintain LN2 in its sub-cooled state is by providing refrigeration with the help of Reverse Brayton Cryo-cooler (RBC). The refrigeration requirement is 10 kW for continuously sub-cooling LN2 from 72 K to 65 K for cooling 1 km length of HTS cable [1]. In this paper, a parametric evaluation of RBC for sub-cooling LN2 has been performed using helium as a process fluid. Exergy approach has been adopted for this analysis. A commercial process simulator, Aspen HYSYS® V8.6 has been used for this purpose. The critical components have been identified and their exergy destruction and exergy efficiency have been obtained for a given heat load condition.

  16. Critical of the concept of exergy

    International Nuclear Information System (INIS)

    Mora Casal, Rene Alejandro

    2015-01-01

    Exergy is a concept that, since its invention sixty years ago, has gained popularity and has extended beyond engineering applications. However, a deep study of this concept reveals problems and inconsistencies, both of theoretical type and of application. Six problems are identified and discussed: ambiguous notation, ambiguous reference states, applicability to real processes, redundancy with respect to other thermodynamic properties, inconsistency between the concepts of exergy and lost work, and applicability of the exergetic analysis results. Some roads to solution for these problems are proposed, being the fifth one the most difficult to solve, as it requires a redefinition of exergy. (author) [es

  17. Exergy energy, environment and sustainable development

    CERN Document Server

    Dincer, Ibrahim; Rosen, Marc A

    2007-01-01

    This book deals with exergy and its applications to various energy systems and applications as a potential tool for design, analysis and optimization, and its role in minimizing and/or eliminating environmental impacts and providing sustainable development. In this regard, several key topics ranging from the basics of the thermodynamic concepts to advanced exergy analysis techniques in a wide range of applications are covered as outlined in the contents. - Comprehensive coverage of exergy and its applications - Connects exergy with three essential areas in terms of energy, environment and sustainable development - Presents the most up-to-date information in the area with recent developments - Provides a number of illustrative examples, practical applications, and case studies - Easy to follow style, starting from the basics to the advanced systems.

  18. Characterization and Exergy Analysis of Triphenyl Borate

    International Nuclear Information System (INIS)

    Acarali, N. B.

    2015-01-01

    In this study, unlike from the literature, boron oxide, borax decahydrate, boric acid and borax pentahydrate as boron sources were used to synthesize Triphenyl Borate (TPB). The reactions of TPB were carried out by using both phenol and various boron sources in inert water-immiscible organic solvent successfully. On the basis of analyzes (FT-IR, SEM, TGA/DSC) obtained, it was seen that phenol acted as a support to borate structure framework and thermal characterisation of the amorphous solid under determined conditions suggested that usage of different boron sources had effects for glass transition temperature in TPB production. The exergy analysis was performed to the TPB production to determine efficiency. The exergy analysis showed that the highest exergy efficiency was obtained by using boron oxide as a boron source. Consequently, all analyses results showed that TPB was produced successfully. Accordingly, characterization and exergy analysis supported each other. (author)

  19. Performance analysis of organic Rankine cycles using different working fluids

    Directory of Open Access Journals (Sweden)

    Zhu Qidi

    2015-01-01

    Full Text Available Low-grade heat from renewable or waste energy sources can be effectively recovered to generate power by an organic Rankine cycle (ORC in which the working fluid has an important impact on its performance. The thermodynamic processes of ORCs using different types of organic fluids were analyzed in this paper. The relationships between the ORC’s performance parameters (including evaporation pressure, condensing pressure, outlet temperature of hot fluid, net power, thermal efficiency, exergy efficiency, total cycle irreversible loss, and total heat-recovery efficiency and the critical temperatures of organic fluids were established based on the property of the hot fluid through the evaporator in a specific working condition, and then were verified at varied evaporation temperatures and inlet temperatures of the hot fluid. Here we find that the performance parameters vary monotonically with the critical temperatures of organic fluids. The values of the performance parameters of the ORC using wet fluids are distributed more dispersedly with the critical temperatures, compared with those of using dry/isentropic fluids. The inlet temperature of the hot fluid affects the relative distribution of the exergy efficiency, whereas the evaporation temperature only has an impact on the performance parameters using wet fluid.

  20. Touch sensitive electrorheological fluid based tactile display

    Science.gov (United States)

    Liu, Yanju; Davidson, Rob; Taylor, Paul

    2005-12-01

    A tactile display is programmable device whose controlled surface is intended to be investigated by human touch. It has a great number of potential applications in the field of virtual reality and elsewhere. In this research, a 5 × 5 tactile display array including electrorheological (ER) fluid has been developed and investigated. Force responses of the tactile display array have been measured while a probe was moved across the upper surface. The purpose of this was to simulate the action of touch performed by human finger. Experimental results show that the sensed surface information could be controlled effectively by adjusting the voltage activation pattern imposed on the tactels. The performance of the tactile display is durable and repeatable. The touch sensitivity of this ER fluid based tactile display array has also been investigated in this research. The results show that it is possible to sense the touching force normal to the display's surface by monitoring the change of current passing through the ER fluid. These encouraging results are helpful for constructing a new type of tactile display based on ER fluid which can act as both sensor and actuator at the same time.

  1. Exergy Analysis of Complex Ship Energy Systems

    Directory of Open Access Journals (Sweden)

    Pierre Marty

    2016-04-01

    Full Text Available With multiple primary and secondary energy converters (diesel engines, steam turbines, waste heat recovery (WHR and oil-fired boilers, etc. and extensive energy networks (steam, cooling water, exhaust gases, etc., ships may be considered as complex energy systems. Understanding and optimizing such systems requires advanced holistic energy modeling. This modeling can be done in two ways: The simpler approach focuses on energy flows, and has already been tested, approved and presented; a new, more complicated approach, focusing on energy quality, i.e., exergy, is presented in this paper. Exergy analysis has rarely been applied to ships, and, as a general rule, the shipping industry is not familiar with this tool. This paper tries to fill this gap. We start by giving a short reminder of what exergy is and describe the principles of exergy modeling to explain what kind of results should be expected from such an analysis. We then apply these principles to the analysis of a large two-stroke diesel engine with its cooling and exhaust systems. Simulation results are then presented along with the exergy analysis. Finally, we propose solutions for energy and exergy saving which could be applied to marine engines and ships in general.

  2. Exergy of partially coherent thermal radiation

    International Nuclear Information System (INIS)

    Wijewardane, S.; Goswami, Yogi

    2012-01-01

    Exergy of electromagnetic radiation has been studied by a number of researchers for well over four decades in order to estimate the maximum conversion efficiencies of thermal radiation. As these researchers primarily dealt with solar and blackbody radiation, which have a low degree of coherence, they did not consider the partial coherence properties of thermal radiation. With the recent development of surface structures, which can emit radiation with high degree of coherence, the importance of considering the partial coherent properties in exergy calculation has become a necessity as the coherence properties directly influence the entropy of the wave field. Here in this paper we derive an expression for the exergy of quasi-monochromatic radiation using statistical thermodynamics and show that it is identical with the expressions derived using classical thermodynamics. We also present a method to calculate the entropy, thereby the exergy of partially coherent radiation using statistical thermodynamics and a method called matrix treatment of wave field. -- Highlights: ► Considered partial coherence of radiation for the first time to calculate exergy. ► The importance of this method is emphasized with energy conversion examples. ► Derived an expression for the exergy of radiation using statistical thermodynamics. ► Adopted a method to calculate intensity of statistically independent principle wave.

  3. Exergy analysis of industrial ammonia synthesis

    International Nuclear Information System (INIS)

    Kirova-Yordanova, Zornitza

    2004-01-01

    Exergy consumption of ammonia production plants depends strongly on the ammonia synthesis loop design. Due to the thermodynamically limited low degree of conversion of hydrogen-nitrogen mixture to ammonia, industrial ammonia synthesis is implemented as recycle process (so-called 'ammonia synthesis loop'). Significant quantities of reactants are recycled back to reactor, after the removal of ammonia at low temperatures. Modern ammonia synthesis plants use well-developed heat- and cold recovery to improve the reaction heat utilisation and to reduce the refrigeration costs. In this work, the exergy method is applied to estimate the effect of the most important process parameters on the exergy efficiency of industrial ammonia synthesis. A specific approach, including suitable definitions of the system boundaries and process parameters, is proposed. Exergy efficiency indexes are discussed in order to make the results applicable to ammonia synthesis loops of various designs. The dependence of the exergy losses on properly selected independent process parameters is studied. Some results from detailed exergy analysis of the most commonly used ammonia synthesis loop design configurations at a wide range of selected parameters values are shown

  4. Exergy costing for energy saving in combined heating and cooling applications

    International Nuclear Information System (INIS)

    Nguyen, Chan; Veje, Christian T.; Willatzen, Morten; Andersen, Peer

    2014-01-01

    Highlights: • We investigate the basis for cost apportioning of simultaneous heating and cooling. • Two thermoeconomic methods based on energy and exergy costing is demonstrated. • The unit cost of heating and cooling for a heat pump system is found and compared. • Energy costing may obstruct efficient use of energy. • Exergy costing provides the most rational cost apportioning for energy saving. - Abstract: The aim of this study is to provide a price model that motivates energy saving for a combined district heating and cooling system. A novel analysis using two thermoeconomic methods for apportioning the costs to heating and cooling provided simultaneously by an ammonia heat pump is demonstrated. In the first method, referred to as energy costing, a conventional thermoeconomic analysis is used. Here the ammonia heat pump is subject to a thermodynamic analysis with mass and energy balance equations. In the second method referred to as exergy costing, an exergy based economic analysis is used, where exergy balance equations are used in conjunction with mass and energy balance equations. In both costing methods the thermodynamic analysis is followed by an economic analysis which includes investment and operating costs. For both methods the unit costs of heating and cooling are found and compared. The analysis shows that the two methods yield significantly different results. Rather surprisingly, it is demonstrated that the exergy costing method results in about three times higher unit cost for heating than for cooling as opposed to equal unit costs when using the energy method. Further the exergy-based cost for heating changes considerably with the heating temperature while that of cooling is much less affected

  5. Exergy Losses in the Szewalski Binary Vapor Cycle

    Directory of Open Access Journals (Sweden)

    Tomasz Kowalczyk

    2015-10-01

    Full Text Available In this publication, we present an energy and exergy analysis of the Szewalski binary vapor cycle based on a model of a supercritical steam power plant. We used energy analysis to conduct a preliminary optimization of the cycle. Exergy loss analysis was employed to perform a comparison of heat-transfer processes, which are essential for hierarchical cycles. The Szewalski binary vapor cycle consists of a steam cycle bottomed with an organic Rankine cycle installation. This coupling has a negative influence on the thermal efficiency of the cycle. However, the primary aim of this modification is to reduce the size of the power unit by decreasing the low-pressure steam turbine cylinder and the steam condenser. The reduction of the “cold end” of the turbine is desirable from economic and technical standpoints. We present the Szewalski binary vapor cycle in addition to a mathematical model of the chosen power plant’s thermodynamic cycle. We elaborate on the procedure of the Szewalski cycle design and its optimization in order to attain an optimal size reduction of the power unit and limit exergy loss.

  6. Exergy analysis of a novel CHP–GSHP coupling system

    International Nuclear Information System (INIS)

    Kang, Shushuo; Li, Hongqiang; Liu, Lifang; Lei, Jing; Zhang, Guoqiang

    2016-01-01

    Highlights: • Exergy loss distributions and efficiency of the novel system are carried out and discussed. • Essential energy saving character of the novel system is revealed. • Influences of key operation parameter on thermodynamic performance are investigated. - Abstract: A novel natural gas based combined heating and power (CHP) and ground source heat pump (GSHP) coupling system has been suggested and analyzed in terms of first law of thermodynamics. In this paper, the performance of the novel system is investigated from the perspective of second law of thermodynamics, and the calculations are completed by the combination of Aspen plus simulation and theoretical derivation. The research results show that, the novel system can obtain total exergy efficiency 22.58%, about 3.7% higher than the reference system. So as to reveal the essential energy saving character about the novel system, the exergy loss distribution differences between the novel and reference system are discussed. Moreover, the key operation parameter which will affect the performance of the novel system is also investigated. The final research results show that, the novel integration approach will provide a good reference for the other similar high-efficiency energy system.

  7. Modelling the energy and exergy utilisation of the Mexican non-domestic sector: A study by climatic regions

    International Nuclear Information System (INIS)

    García Kerdan, Iván; Morillón Gálvez, David; Raslan, Rokia; Ruyssevelt, Paul

    2015-01-01

    This paper presents the development of a bottom-up stock model to perform a holistic energy study of the Mexican non-domestic sector. The current energy and exergy flows are shown based on a categorisation by climatic regions with the aim of understanding the impact of local characteristics on regional efficiencies. Due to the limited data currently available, the study is supported by the development of a detailed archetype-based stock model using EnergyPlus as a first law analysis tool combined with an existing exergy analysis method. Twenty-one reference models were created to estimate the electric and gas use in the sector. The results indicate that sectoral energy and exergy annual input are 95.37 PJ and 94.28 PJ, respectively. Regional exergy efficiencies were found to be 17.8%, 16.6% and 23.2% for the hot-dry, hot-humid and temperate climates, respectively. The study concludes that significant potential for improvements still exists, especially in the cases of space conditioning, lighting, refrigeration, and cooking where most exergy destructions occur. Additionally, this work highlights that the method described may be further used to study the impact of large-scale refurbishments and promote national regulations and standards for sustainable buildings that takes into consideration energy and exergy indicators. - Highlights: • A bottom-up physics model was developed to analyse the Mexican commercial stock. • A detailed energy analysis by climate, buildings and end-uses is presented. • The Mexican non-domestic sector as a whole has an exergy efficiency of 19.7%. • The lowest regional exergy efficiency is found at the hot-humid region with 16.6%. • By end use, the highest exergy destructions are caused by HVAC and lighting

  8. Energy and exergy utilizations of the Chinese urban residential sector

    International Nuclear Information System (INIS)

    Liu, Yanfeng; Li, Yang; Wang, Dengjia; Liu, Jiaping

    2014-01-01

    Highlights: • The energy and exergy use in China’s urban residential sector between 2002 and 2011 are analyzed. • The primary locations and causes of energy and exergy losses in the CURS are identified. • The large gap between the energy and exergy efficiencies implies great potential for energy saving. • The exergy utilization can be improved by using appropriate technology, management and policy. - Abstract: In this paper, the energy and exergy utilizations in the Chinese urban residential sector (CURS) are analyzed by considering the energy and exergy flows for the years between 2002 and 2011. The energy and exergy efficiencies of this sector are calculated to examine the potential for advancing the ‘true’ energy efficiency and determine the real energy losses. The results demonstrate large differences between the overall energy efficiencies (62.8–70.2%) and the exergy efficiencies (11.0–12.2%) for the years analyzed. The sizable gap between the energy and exergy efficiencies implies a high potential for energy savings in the CURS. Future energy saving strategies should pay more attention to the improvement in exergy efficiencies. Moreover, it is found that direct fuel use constituted the primary exergy losses of the CURS; coal-fired boiler heating systems cause approximately 35% of the total exergy losses. Gas stoves, cogeneration systems, coal stoves and gas water heaters constitute 15.3%, 15%, 5.5% and 4.9% of the total exergy losses, respectively

  9. The utility of environmental exergy analysis for decision making in energy

    International Nuclear Information System (INIS)

    Simpson, Adam P.; Edwards, Chris F.

    2013-01-01

    The analysis framework discussed and employed in this paper utilizes the recent recognition that exergy is a form of environmental free energy to provide a fundamental basis for valuing environmental interactions independent from their secondary impacts. The framework is comprised of two separate components: (1) environmental exergy analysis and (2) anthropocentric sensitivity analysis. Environmental exergy analysis is based on fundamental thermodynamic principles and analysis techniques. It extends the principles of technical exergy analysis to the environment in order to quantify the location, magnitudes, and types of environmental impact—state change, alteration of natural transfers, and destruction change. Anthropocentric sensitivity analysis is based on the concepts of anthropocentric value and anthropocentric sensitivity. It enables the results of environmental exergy analysis to be interpreted for decision making, but at the expense of introducing some subjectivity into the framework. A key attribute of the framework is its ability to evaluate the environmental performance of energy systems on a level playing field, regardless of the specifics of the systems—i.e., resources consumed, products and by-products produced, or system size and time scale. The utility of the analysis framework for decision making is demonstrated in this paper through application to three example energy systems. - Highlights: ► Utilizes the recognition that exergy is a form of environmental free energy. ► Combines environmental exergy analysis and anthropocentric sensitivity analysis. ► Evaluates/compares environmental performance of systems on a level playing field. ► Independence from the system specifics—resources, by-products, sizes, time scales. ► Utility for decision making is demonstrated using real and notional energy systems

  10. Tetra-combined cogeneration system. Exergy and thermo economic evaluation; Sistema tetra combinado de cogeracao. Avaliacao exergetica e termoeconomica

    Energy Technology Data Exchange (ETDEWEB)

    Arriola, Domingo Wilson Garagatti [Sao Paulo Univ., SP (Brazil). Escola Politecnica. Dept. de Engenharia Mecanica]. E-mail: wgarriol@usp.br; Oliveira Junior, Silvio de [Instituto de Pesquisas Tecnologicas (IPT), Sao Paulo, SP (Brazil)]. E-mail: olivsilj@ipt.br

    2000-07-01

    This paper presents the description and the exergy and thermo economic evaluation of a new cogeneration system, called tetra-combined cogeneration system, that generates electricity and chilled water (for air conditioning purposes) and eventually steam. This system is composed of a gas turbine, a heat recovery steam generator, a condensation/extraction steam turbine and a hybrid absorption/steam ejection chiller. The exergy and thermo economic performance (exergy based costs of electricity, steam and chilled water production) of this system is compared with the performances of conventional cogeneration systems, pointing out the advantages and disadvantages of this new system. (author)

  11. Tetra-combined cogeneration system. Exergy and thermoeconomic evaluation; Sistema tetra combinado de cogeracao. Avaliacao exergetica e termoeconomica

    Energy Technology Data Exchange (ETDEWEB)

    Arriola, Domingo Wilson Garagatti [Sao Paulo Univ., SP (Brazil). Escola Politecnica. Dept. de Engenharia Mecanica]. E-mail: wgarriol@usp.br; Oliveira Junior, Silvio de [Instituto de Pesquisas Tecnologicas (IPT), Sao Paulo, SP (Brazil)]. E-mail: olivsilj@ipt.br

    2000-07-01

    The description and the exergy and thermo economic evaluation of a new cogeneration system, called tetra-combined cogeneration system, that generates electricity and chilled water (for air conditioning purposes) and eventually steam is presented. This system is composed of a gas turbine, a heat recovery steam generator, a condensation/extraction steam turbine and a hybrid absorption/steam ejection chiller.The exergy and thermo economic performance (exergy based costs of electricity, steam and chilled water production) of this system is compared with the performances of conventional cogeneration systems, pointing out the advantages and disadvantages of this new system. (author)

  12. Exergy and environmental comparison of the end use of vehicle fuels: The Brazilian case

    International Nuclear Information System (INIS)

    Flórez-Orrego, Daniel; Silva, Julio A.M.; Oliveira Jr, Silvio de

    2015-01-01

    Highlights: • Total and non-renewable exergy costs of Brazilian transportation service are evaluated. • Specific CO 2 emissions of the Brazilian transportation service are determined. • Overall exergy efficiency of the end use of vehicle fuels in transportation sector is calculated. • A comparative extended analysis of the production and end use of transportation fuels is presented. - Abstract: In this work, a comparative exergy and environmental analysis of the vehicle fuel end use is presented. This analysis comprises petroleum and natural gas derivatives (including hydrogen), biofuels (ethanol and biodiesel), and their mixtures, besides of the electricity generated in the Brazilian electricity mix, intended to be used in plug in electric vehicles. The renewable and non-renewable unit exergy costs and CO 2 emission cost are proposed as suitable indicators for assessing the renewable exergy consumption intensity and the environmental impact, and for quantifying the thermodynamic performance of the transportation sector. This allows ranking the energy conversion processes along the vehicle fuels production routes and their end use, so that the best options for the transportation sector can be determined and better energy policies may be issued. It is found that if a drastic CO 2 emissions abatement of the sector is pursued, a more intensive utilization of ethanol in the Brazilian transportation sector mix is advisable. However, as the overall exergy conversion efficiency of the sugar cane industry is still very low, which increases the unit exergy cost of ethanol, better production and end use technologies are required. Nonetheless, with the current scenario of a predominantly renewable Brazilian electricity mix, based on more than 80% of renewable sources, this source consolidates as the most promising energy source to reduce the large amount of greenhouse gas emissions which transportation sector is responsible for

  13. Operation optimization of a distributed energy system considering energy costs and exergy efficiency

    International Nuclear Information System (INIS)

    Di Somma, M.; Yan, B.; Bianco, N.; Graditi, G.; Luh, P.B.; Mongibello, L.; Naso, V.

    2015-01-01

    Highlights: • Operation optimization model of a Distributed Energy System (DES). • Multi-objective strategy to optimize energy cost and exergy efficiency. • Exergy analysis in building energy supply systems. - Abstract: With the growing demand of energy on a worldwide scale, improving the efficiency of energy resource use has become one of the key challenges. Application of exergy principles in the context of building energy supply systems can achieve rational use of energy resources by taking into account the different quality levels of energy resources as well as those of building demands. This paper is on the operation optimization of a Distributed Energy System (DES). The model involves multiple energy devices that convert a set of primary energy carriers with different energy quality levels to meet given time-varying user demands at different energy quality levels. By promoting the usage of low-temperature energy sources to satisfy low-quality thermal energy demands, the waste of high-quality energy resources can be reduced, thereby improving the overall exergy efficiency. To consider the economic factor as well, a multi-objective linear programming problem is formulated. The Pareto frontier, including the best possible trade-offs between the economic and exergetic objectives, is obtained by minimizing a weighted sum of the total energy cost and total primary exergy input using branch-and-cut. The operation strategies of the DES under different weights for the two objectives are discussed. The operators of DESs can choose the operation strategy from the Pareto frontier based on costs, essential in the short run, and sustainability, crucial in the long run. The contribution of each energy device in reducing energy costs and the total exergy input is also analyzed. In addition, results show that the energy cost can be much reduced and the overall exergy efficiency can be significantly improved by the optimized operation of the DES as compared with the

  14. Variable flexure-based fluid filter

    Science.gov (United States)

    Brown, Steve B.; Colston, Jr., Billy W.; Marshall, Graham; Wolcott, Duane

    2007-03-13

    An apparatus and method for filtering particles from a fluid comprises a fluid inlet, a fluid outlet, a variable size passage between the fluid inlet and the fluid outlet, and means for adjusting the size of the variable size passage for filtering the particles from the fluid. An inlet fluid flow stream is introduced to a fixture with a variable size passage. The size of the variable size passage is set so that the fluid passes through the variable size passage but the particles do not pass through the variable size passage.

  15. Exergy analysis and optimization of a thermal management system with phase change material for hybrid electric vehicles

    International Nuclear Information System (INIS)

    Javani, N.; Dincer, I.; Naterer, G.F.; Yilbas, B.S.

    2014-01-01

    In the present study, energy and exergy analyses are conducted to investigate a new cooling system of hybrid electric vehicles (HEVs). A latent heat thermal energy storage system is integrated with an active refrigeration cycle where octadecane is selected as the phase change material (PCM). The liquid cooling system flows through the chiller following a conventional vapor compression cooling cycle. The latent heat shell and the tube heat exchanger operate in parallel with the chiller and a fraction of coolant enters the heat exchanger and, therefore, decreases the heat load of the chiller, leading to a lower work required by the compressor. The exergy destruction rate and the exergy efficiency of each component in a hybrid thermal management system (TMS) are calculated. In addition, the effects of parameters such as the fraction of coolant entering the heat storage system (PCM mass fraction), evaporator temperature, and compressor pressure ratio on the system performance are investigated. The findings of the exergy analysis reveal that the overall exergy efficiency of the system with PCM presence is 31%, having the largest exergy destruction rate of 0.4 kW and the heat exchangers have lower exergy efficiency as compared to other components. In addition, the results of the parametric study show that an increase in PCM mass fraction results in an increase in exergy efficiency of the system. An environmental impact assessment is also conducted and the results show that an increase in exergy efficiency of the cooling system reduces greenhouse gasses and also increases the sustainability of the system. Moreover, a multi-objective optimization using the genetic algorithm is performed by incorporating two objective functions, namely exergy efficiency to be maximized and total cost rate of the system to be minimized. A Pareto frontier is obtained and a single desirable optimal solution is selected based on LINMAP decision-making process. The results show that the maximum

  16. A Thermorisk framework for the analysis of energy systems by combining risk and exergy analysis

    International Nuclear Information System (INIS)

    Cassetti, G.; Colombo, E.; Zio, E.

    2016-01-01

    Highlights: • An exergy based analysis for improving efficiency and safety of energy systems is presented. • The relation between thermodynamic parameters and the safety characteristics is identified. • Possible modifications in the process are indicated to improve the safety of the system. - Abstract: The impact of energy production, transformation and use on the environmental resources encourage to understand the mechanisms of resource degradation and to develop proper analyses to reduce the impact of the energy systems on the environment. At the technical level, most attempts for reducing the environmental impact of energy systems focus on the improvement of process efficiency. One way toward an integrated approach is that of adopting exergy analysis for assessing efficiency and test improving design and operation solutions. The paper presents an exergy based analysis for improving efficiency and safety of energy systems, named Thermorisk analysis. The purpose of the Thermorisk analysis is to supply information to control, and eventually reduce, the risk of the systems (i.e. risk of accidents) by acting on the thermodynamic parameters and safety characteristics in the same frame. The proper combination of exergy and risk analysis allows monitoring the effects of efficiency improvement on the safety of the systems analyzed. A case study is presented, showing the potential of the analysis to identify the relation between the exergy efficiency and the risk of the system analyzed, and the contribution of inefficiencies on the safety of the process. Possible modifications in the process are indicated to improve the safety of the system.

  17. Thermodynamic exergy analysis for small modular reactor in nuclear hybrid energy system - 15110

    International Nuclear Information System (INIS)

    Boldon, L.; Liu, L.; Sabharwall, P.; Rabiti, C.; Bragg-Sitton, S.M.

    2015-01-01

    To assess the inherent value of energy in a thermal system, it is necessary to understand both the quantity and quality of energy available or the exergy. We study the case where nuclear energy through a small modular reactor (SMR) is supplementing the available wind energy through storage to meet the needs of the electrical grid. Nuclear power is also being used for the production of hydrogen via high temperature steam electrolysis. For a SMR exergy analysis, both the physical and economic environments must be considered. The physical environment incorporates the energy, raw materials, and reference environment, where the reference environment refers to natural resources available without limit and without cost. This paper aims to explore the use of exergy analysis methods to estimate and optimize SMR resources and costs for individual subsystems, based on thermodynamic principles-resource utilization and efficiency. The paper will present background information on exergy theory; identify the core subsystems in an SMR plant coupled with storage systems in support of renewable energy and hydrogen production; perform a thermodynamic exergy analysis; determine the cost allocation among these subsystems; and calculate unit 'exergetic' costs, unit 'exergo-economic' costs, and first and second law efficiencies. Exergetic and 'exergo-economic' costs ultimately determine how individual subsystems contribute to overall profitability and how efficiencies and consumption may be optimized to improve profitability, making SMRs more competitive with other generation technologies

  18. Exergy analysis of synthetic biofuel production via fast pyrolysis and hydroupgrading

    International Nuclear Information System (INIS)

    Peters, Jens F.; Petrakopoulou, Fontina; Dufour, Javier

    2015-01-01

    This paper presents the first assessment of the exergetic performance of a biorefinery process based on catalytic hydroupgrading of bio-oil from fast pyrolysis. Lignocellulosic biomass is converted into bio-oil through fast pyrolysis, which is then upgraded to synthetic fuels in a catalytic hydrotreating process. The biorefinery process is simulated numerically using commercial software and analyzed using exergetic analysis. Exergy balances are defined for each component of the plant and the exergetic efficiencies and exergy destruction rates are calculated at the component, section and plant level, identifying thermodynamic inefficiencies and revealing the potential for further improvement of the process. The overall biofuel process results in an exergetic efficiency of 60.1%, while the exergetic efficiency of the upgrading process in the biorefinery alone is 77.7%. Within the biorefinery, the steam reforming reactor is the main source of inefficiencies, followed by the two hydrotreating reactors. In spite of the high operating pressures in the hydrotreating section, the compressors have little impact on the total exergy destruction. Compared to competing lignocellulosic biofuel processes, like gasification with Fischer–Tropsch synthesis or lignocellulosic ethanol processes, the examined system achieves a significantly higher exergetic efficiency. - Highlights: • Exergetic analysis of a biorefinery for bio-oil hydroupgrading. • Detailed simulation model using 83 model compounds. • Exergy destruction quantified in each component of the plant. • Exergetic efficiency and potential for improvement determined on component level. • Highest exergy destruction in the pyrolysis plant and the steam reformer

  19. Exergy efficiency enhancement of MSF desalination by heat recovery from hot distillate water stages

    International Nuclear Information System (INIS)

    Al-Weshahi, Mohammed A.; Anderson, Alexander; Tian, Guohong

    2013-01-01

    This detailed exergy analysis of a 3800 m 3 /h Multi-Stage Flash (MSF) desalination plant is based on the latest published thermodynamics properties of water and seawater. The parameters of the study were extracted from a validated model of MSF desalination using IPSEpro software. The results confirmed that the overall exergy efficiency of the unit is lower than would be desirable at only 5.8%. Exergy inputs were destroyed by 55%, 17%, 10%, 4.3%, and 14% respectively, in the heat recovery stages, brine heater, heat rejection stages, pumps and brine streams disposal. Moreover, the detail of the study showed that the lowest exergy destruction occurs in the first stage, increasing gradually in heat recovery stages and sharply in heat rejection stages. The study concludes that recovering the heat from the hot distillate water stages can improve unit exergy efficiency from its low 5.8% to a more economical 14%, with the hot water parameters suitable for powering other thermal systems such as absorption chiller and multi-effect desalination

  20. Residential solar air conditioning: Energy and exergy analyses of an ammonia–water absorption cooling system

    International Nuclear Information System (INIS)

    Aman, J.; Ting, D.S.-K.; Henshaw, P.

    2014-01-01

    Large scale heat-driven absorption cooling systems are available in the marketplace for industrial applications but the concept of a solar driven absorption chiller for air-conditioning applications is relatively new. Absorption chillers have a lower efficiency than compression refrigeration systems, when used for small scale applications and this restrains the absorption cooling system from air conditioning applications in residential buildings. The potential of a solar driven ammonia–water absorption chiller for residential air conditioning application is discussed and analyzed in this paper. A thermodynamic model has been developed based on a 10 kW air cooled ammonia–water absorption chiller driven by solar thermal energy. Both energy and exergy analyses have been conducted to evaluate the performance of this residential scale cooling system. The analyses uncovered that the absorber is where the most exergy loss occurs (63%) followed by the generator (13%) and the condenser (11%). Furthermore, the exergy loss of the condenser and absorber greatly increase with temperature, the generator less so, and the exergy loss in the evaporator is the least sensitive to increasing temperature. -- Highlights: • 10 kW solar thermal driven ammonia–water air cooled absorption chiller is investigated. • Energy and exergy analyses have been done to enhance the thermal performance. • Low driving temperature heat sources have been optimized. • The efficiencies of the major components have been evaluated

  1. Exergy analysis of transcritical carbon dioxide refrigeration cycle with an expander

    International Nuclear Information System (INIS)

    Yang Junlan; Ma Yitai; Li Minxia; Guan Haiqing

    2005-01-01

    In this paper, a comparative study is performed for the transcritical carbon dioxide refrigeration cycles with a throttling valve and with an expander, based on the first and second laws of thermodynamics. The effects of evaporating temperature and outlet temperature of gas cooler on the optimal heat rejection pressure, the coefficients of performance (COP), the exergy losses, and the exergy efficiencies are investigated. In order to identify the amounts and locations of irreversibility within the two cycles, exergy analysis is employed to study the thermodynamics process in each component. It is found that in the throttling valve cycle, the largest exergy loss occurs in the throttling valve, about 38% of the total cycle irreversibility. In the expander cycle, the irreversibility mainly comes from the gas cooler and the compressor, approximately 38% and 35%, respectively. The COP and exergy efficiency of the expander cycle are on average 33% and 30% higher than those of the throttling valve cycle, respectively. It is also concluded that an optimal heat rejection pressure can be obtained for all the operating conditions to maximize the COP. The analysis results are of significance to provide theoretical basis for optimization design and operation control of the transcritical carbon dioxide cycle with an expander

  2. Exergy Analysis of the Revolving Vane Compressed Air Engine

    Directory of Open Access Journals (Sweden)

    Alison Subiantoro

    2016-01-01

    Full Text Available Exergy analysis was applied to a revolving vane compressed air engine. The engine had a swept volume of 30 cm3. At the benchmark conditions, the suction pressure was 8 bar, the discharge pressure was 1 bar, and the operating speed was 3,000 rev·min−1. It was found that the engine had a second-law efficiency of 29.6% at the benchmark conditions. The contributors of exergy loss were friction (49%, throttling (38%, heat transfer (12%, and fluid mixing (1%. A parametric study was also conducted. The parameters to be examined were suction reservoir pressure (4 to 12 bar, operating speed (2,400 to 3,600 rev·min−1, and rotational cylinder inertia (0.94 to 2.81 g·mm2. The study found that a higher suction reservoir pressure initially increased the second-law efficiency but then plateaued at about 30%. With a higher operating speed and a higher cylinder inertia, second-law efficiency decreased. As compared to suction pressure and operating speed, cylinder inertia is the most practical and significant to be modified.

  3. Exergy analysis of photovoltaic solar collector

    International Nuclear Information System (INIS)

    Sopian, K.; Othman, M.Y.Hj.

    1998-01-01

    The exergy analysis (availability or second law analysis) is applied to the photovoltaic thermal solar collector. Photovoltaic thermal collector is a special type of solar collector where electricity and heat are produced simultaneously. The electricity produced from the photovoltaic thermal collector is all converted into useful work. The available quantity of the heat collected can readily be determined by taking into account both the quantity (heat quantity) and quality ( a function of temperature) of the thermal energy. Therefore, using the concept of exergy allows heat produced from the thermal collector and the electricity generated from the photovoltaic cells to be compared or to be evaluated on the basis of a common measure such as the effectiveness on solar energy collection or the total amount of available energy. In this paper, the effectiveness of solar energy collection is called combined photovoltaic thermal exergy efficiency. An experimental setup of a double pas photovoltaic thermal solar collector has been deigned, fabricated and tested. (author)

  4. Energy, Entropy and Exergy in Communication Networks

    Directory of Open Access Journals (Sweden)

    Slavisa Aleksic

    2013-10-01

    Full Text Available The information and communication technology (ICT sector is continuously growing, mainly due to the fast penetration of ICT into many areas of business and society. Growth is particularly high in the area of technologies and applications for communication networks, which can be used, among others, to optimize systems and processes. The ubiquitous application of ICT opens new perspectives and emphasizes the importance of understanding the complex interactions between ICT and other sectors. Complex and interacting heterogeneous systems can only properly be addressed by a holistic framework. Thermodynamic theory, and, in particular, the second law of thermodynamics, is a universally applicable tool to analyze flows of energy. Communication systems and their processes can be seen, similar to many other natural processes and systems, as dissipative transformations that level differences in energy density between participating subsystems and their surroundings. This paper shows how to apply thermodynamics to analyze energy flows through communication networks. Application of the second law of thermodynamics in the context of the Carnot heat engine is emphasized. The use of exergy-based lifecycle analysis to assess the sustainability of ICT systems is shown on an example of a radio access network.

  5. Exergy analysis of a cogeneration power plant

    International Nuclear Information System (INIS)

    Núñez Bosch, Osvaldo Manuel

    2015-01-01

    In the following study exergetic evaluation of a cogeneration power plant in operation with installed electrical capacity of 24 MW and process heat demand of 190 MW it is performed. The main objective of the research was to determine the influence of the increase in power generation capacity, raising the superheated steam parameters and the number of regenerative heaters on the second law efficiency and irreversibilities in the different components of the plant. To study the power plant was divided into subsystems: steam generator blowdown expander, main steam pipe, steam turbine regenerative heaters, reduction system, deaerator and pumps. The study results show that exergy losses and irreversibilities differ widely from one subsystem to another. In general, the total irreversibility accounted for 70.7% of primary fuel availability. The steam generator subsystem had the highest contribution to the irreversibility of the plant by 54%. It was determined that the increased steam parameters helps reduce the irreversibility and increase the exergetic efficiency of installation. The suppression of the reduction and incorporation of extraction-condensing turbine produce the same effect and helps to reduce power consumption from the national grid. Based on the results recommendations for improving plant efficiency are made. (full text)

  6. Exergy destruction and losses on four North Sea offshore platforms: A comparative study of the oil and gas processing plants

    DEFF Research Database (Denmark)

    Voldsund, Mari; Nguyen, Tuong-Van; Elmegaard, Brian

    2014-01-01

    The oil and gas processing plants of four North Sea offshore platforms are analysed and compared, based on the exergy analysis method. Sources of exergy destruction and losses are identified and the findings for the different platforms are compared. Different platforms have different working...... conditions, which implies that some platforms need less heat and power than others. Reservoir properties and composition vary over the lifetime of an oil field, and therefore maintaining a high efficiency of the processing plant is challenging. The results of the analysis show that 27%-57% of the exergy...... destruction take place in the gas treatment sections, 13%-29% take place in the gas recompression sections and 10%-24% occur in the production manifolds. The exergy losses with flared gas are significant for two of the platforms. The exact potential for energy savings and for enhancing system performances...

  7. Cumulative exergy losses associated with the production of lead metal

    Energy Technology Data Exchange (ETDEWEB)

    Szargut, J [Technical Univ. of Silesia, Gliwice (PL). Inst. of Thermal-Engineering; Morris, D R [New Brunswick Univ., Fredericton, NB (Canada). Dept. of Chemical Engineering

    1990-08-01

    Cumulative exergy losses result from the irreversibility of the links of a technological network leading from raw materials and fuels extracted from nature to the product under consideration. The sum of these losses can be apportioned into partial exergy losses (associated with particular links of the technological network) or into constituent exergy losses (associated with constituent subprocesses of the network). The methods of calculation of the partial and constituent exergy losses are presented, taking into account the useful byproducts substituting the major products of other processes. Analyses of partial and constituent exergy losses are made for the technological network of lead metal production. (author).

  8. An Innovative Use of Renewable Ground Heat for Insulation in Low Exergy Building Systems

    Directory of Open Access Journals (Sweden)

    Hansjürg Leibundgut

    2012-08-01

    Full Text Available Ground heat is a renewable resource that is readily available for buildings in cool climates, but its relatively low temperature requires the use of a heat pump to extract it for heating. We developed a system that uses low temperature ground heat directly in a building wall to reduce transmission heat losses. The Active Low Exergy Geothermal Insulation Systems (ALEGIS minimizes exergy demand and maximizes the use of renewable geothermal heat from the ground. A fluid is pumped into a small pipe network in an external layer of a wall construction that is linked to a ground heat source. This decouples the building from the outside temperature, therefore eliminating large peak demands and reducing the primary energy demand. Our steady-state analysis shows that at a design temperature of −10 °C the 6 cm thick active insulation system has equivalent performance to 11 cm of passive insulation. Our comparison of heating performance of a building with our active insulation system versus a building with static insulation of the same thickness shows a 15% reduction in annual electricity demand, and thus exergy input. We present an overview of the operation and analysis of our low exergy concept and its modeled performance.

  9. A METHOD FOR EXERGY ANALYSIS OF SUGARCANE BAGASSE BOILERS

    Directory of Open Access Journals (Sweden)

    CORTEZ L.A.B.

    1998-01-01

    Full Text Available This work presents a method to conduct a thermodynamic analysis of sugarcane bagasse boilers. The method is based on the standard and actual reactions which allows the calculation of the enthalpies of each process subequation and the exergies of each of the main flowrates participating in the combustion. The method is presented using an example with real data from a sugarcane bagasse boiler. A summary of the results obtained is also presented together based on the 1st Law of Thermodynamics analysis, the exergetic efficiencies, and the irreversibility rates. The method presented is very rigorous with respect to data consistency, particularly for the flue gas composition.

  10. Energy efficiency analysis of styrene production by adiabatic ethylbenzene dehydrogenation using exergy analysis and heat integration

    Directory of Open Access Journals (Sweden)

    Ali Emad

    2018-03-01

    Full Text Available Styrene is a valuable commodity for polymer industries. The main route for producing styrene by dehydrogenation of ethylbenzene consumes a substantial amount of energy because of the use of high-temperature steam. In this work, the process energy requirements and recovery are studied using Exergy analysis and Heat Integration (HI based on Pinch design method. The amount of steam plays a key role in the trade-off between Styrene yield and energy savings. Therefore, optimizing the operating conditions for energy reduction is infeasible. Heat integration indicated an insignificant reduction in the net energy demand and exergy losses, but 24% and 34% saving in external heating and cooling duties, respectively. When the required steam is generated by recovering the heat of the hot reactor effluent, a considerable saving in the net energy demand, as well as the heating and cooling utilities, can be achieved. Moreover, around 68% reduction in the exergy destruction is observed.

  11. Performance Analysis of 20MW gas turbine power plant by Energy and Exergy Methods

    International Nuclear Information System (INIS)

    Lebele-Alawa, B. T.; Asuo, J. M.

    2013-01-01

    Energy and exergy analysis were conducted to evaluate the optimal performance of a 20 MW gas turbine power plant. The energy analysis was based on First Law of Thermodynamics, while the exergy method used both First and Second Laws of Thermodynamics. The locations and magnitude of losses which inhibited the performance of the power plant were identified by balance system equations. The internal losses associated with each plant component were estimated for improvement to be made to such component for maximum power output. The energy efficiency was 20.73 %, while the exergeric efficiency was 16.39 %; but the exergy loss of 38.62 % in the combustor was the largest among the components of plant. (au)

  12. Comparative energy and exergy performance assessments of a microcogenerator unit in different electricity mix scenarios

    International Nuclear Information System (INIS)

    Gonçalves, Pedro; Angrisani, Giovanni; Roselli, Carlo; Gaspar, Adélio R.; Gameiro da Silva, Manuel

    2013-01-01

    Highlights: • Experimental and energy–exergy modelling of a 6 kW micro-combined heat and power unit. • Evaluation of energy and exergy efficiencies for performance assessment. • Use of exergy and energy indicators for comparison with a reference system. • Use of different renewables supply options into the electric and heat reference system. • The electric grid mix of Portugal and Italy is used and discussed. - Abstract: The Directive 2004/8/EC on the promotion of cogeneration proposes a comparative indicator based on primary energy savings, neglecting some important thermodynamic aspects, such as exergy. This study aims to compare and discuss the usefulness of a set of complementary indicators for performance assessments of cogeneration systems, concerning thermodynamic principles based on first and second law (the exergy approach). As case study, a 6 kW electric output micro-combined heat and power unit was experimentally tested and a model of the unit was developed in TRNSYS. Considering as reference a set of different heat and electricity scenarios, including the actual electric mixes of Portugal and Italy, the indicators case incon (PES) and Primary and Total Irreversibilities Savings (PIS and TIS), as well as energy and exergy renewability ratios were assessed and discussed. The results show that the use of MCHP has higher advantages for the Italian electric grid, than an equivalent scenario considering the Portuguese electric network as reference. As result, for a particular scenario analysed, PES and PIS have 3% and 6% for Portugal, and 10% and 18% for Italy, respectively. Furthermore, for one particular scenario evaluated, the indicators energetic and exergetic renewability ratios have 23% and 14%, respectively for the Portuguese electric grid, and 19% and 10% for the Italian electric system

  13. Exergy metrication of radiant panel heating and cooling with heat pumps

    International Nuclear Information System (INIS)

    Kilkis, Birol

    2012-01-01

    Highlights: ► Rational Exergy Management Model analytically relates heat pumps and radiant panels. ► Heat pumps driven by wind energy perform better with radiantpanels. ► Better CO 2 mitigation is possible with wind turbine, heat pump, radiant panel combination. ► Energy savings and thermo-mechanical performance are directly linked to CO 2 emissions. - Abstract: Radiant panels are known to be energy efficient sensible heating and cooling systems and a suitable fit for low-exergy buildings. This paper points out the little known fact that this may not necessarily be true unless their low-exergy demand is matched with low-exergy waste and alternative energy resources. In order to further investigate and metricate this condition and shed more light on this issue for different types of energy resources and energy conversion systems coupled to radiant panels, a new engineering metric was developed. Using this metric, which is based on the Rational Exergy Management Model, true potential and benefits of radiant panels coupled to ground-source heat pumps were analyzed. Results provide a new perspective in identifying the actual benefits of heat pump technology in curbing CO 2 emissions and also refer to IEA Annex 49 findings for low-exergy buildings. Case studies regarding different scenarios are compared with a base case, which comprises a radiant panel system connected to a natural gas-fired condensing boiler in heating and a grid power-driven chiller in cooling. Results show that there is a substantial CO 2 emission reduction potential if radiant panels are optimally operated with ground-source heat pumps driven by renewable energy sources, or optimally matched with combined heat and power systems, preferably running on alternative fuels.

  14. Energy and exergy analysis of counter flow wet cooling towers

    Directory of Open Access Journals (Sweden)

    Saravanan Mani

    2008-01-01

    Full Text Available Cooling tower is an open system direct contact heat exchanger, where it cools water by both convection and evaporation. In this paper, a mathematical model based on heat and mass transfer principle is developed to find the outlet condition of water and air. The model is solved using iterative method. Energy and exergy analysis infers that inlet air wet bulb temperature is found to be the most important parameter than inlet water temperature and also variation in dead state properties does not affect the performance of wet cooling tower. .

  15. Thermodynamic evaluation of distillation columns using exergy loss profiles: a case study on the crude oil atmospheric distillation column

    Energy Technology Data Exchange (ETDEWEB)

    Tarighaleslami, Amir Hossein [Mahshahr Branch, Islamic Azad University, Chemical Engineering Faculty, Mahshar, Khouzestan (Iran, Islamic Republic of); Omidkhah, Mohammad Reza [Tarbiat Modares University, Chemical Engineering Department, Faculty of Engineering, Tehran (Iran, Islamic Republic of); Ghannadzadeh, Ali [University of Toulouse, Department of Process and System Engineering, Chemical Engineering Laboratory, Toulouse (France); Hoseinzadeh Hesas, Roozbeh [University of Malaya, Chemical Engineering Department, Faculty of Engineering, Kuala Lumpur (Malaysia)

    2012-06-15

    This paper presents a case study on the crude oil atmospheric distillation column of Tabriz refinery plant to show the applicability of exergy loss profiles in thermodynamic examination of the different retrofit options. The atmospheric distillation column of Tabriz refinery has been revamped as a consequence of increase of the plant capacity to 100,000 bpd. To cover the deficit of feedstock of the revamped unit, a blend of the existing feedstock with imported crude oil is used as a feedstock. However, to investigate how the blend of these two different types of crudes as a feedstock has an influence on the operating conditions, the examination of the column is needed. Exergy as a comprehensive thermodynamic property which translates the temperature, pressure and composition change into a common unit has been chosen to evaluate the distillation column thermodynamically. Furthermore, the exergy loss profile of the base case serves as a scoping tool to pinpoint the source of inefficiencies. Then, the exergy loss profile as a screening tool has found the retrofit options which are likely to yield greatest energy saving from a list of retrofit options proposed by the industrial partner. In the presented case study, the exergy loss profile identifies the best retrofit option with 17.16% reduction in exergy losses, which finally lead to 3.6% reduction of primary fuel demand. (orig.)

  16. Application of the exergy method to the environmental impact estimation: The nitric acid production as a case study

    International Nuclear Information System (INIS)

    Kirova-Yordanova, Zornitza

    2011-01-01

    In this work the exergy method is used to compare various methods for removal of NO x from waste (tail) gas released into the atmosphere from nitric acid production plants with respect to their overall environmental impact. Three basic methods for NO x abatement are analysed: selective catalytic reduction (SCR), non-selective catalytic reduction (NSCR) and extended absorption. The positive and negative effects and the net effect from the NO x abatement are calculated. The following exergy-based indicators are used for comparing the energy efficiency and the environmental impact of different treatment processes as a result from pollutants removal: reduction of the exergy of the emissions from the whole process route (ammonia and nitric acid production units); exergy of the additional emissions, arising as a result of the treatment process; total net reduction of the exergy consumption, Cumulative Energy Consumption (CEnC) and Cumulative Exergy Consumption (CExC) of natural resources as a result of the waste flows treatment. -- Highlights: → A thermodynamic study of the effects of three NO x abatement methods. → A comparison of the positive, negative and overall net effects of the three methods. → The best overall results are obtained for the extended absorption method. → The selective catalytic reduction method is estimated as unsatisfactory. → The non-selective catalytic reduction method could benefit from improved catalysts.

  17. The analysis of exergy and cash flow

    International Nuclear Information System (INIS)

    Weimin, H.

    1989-01-01

    The paper presents the analysis of the economic content of exergy parameter and the thermodynamical analogy of the analysis of cash flow, and gives out the reasonable foundations of the analysis of heat economy. The thoughts of optimum design of the combination of heat economic analysis and investment policy are also put forward

  18. Fluid, solid and fluid-structure interaction simulations on patient-based abdominal aortic aneurysm models.

    Science.gov (United States)

    Kelly, Sinead; O'Rourke, Malachy

    2012-04-01

    This article describes the use of fluid, solid and fluid-structure interaction simulations on three patient-based abdominal aortic aneurysm geometries. All simulations were carried out using OpenFOAM, which uses the finite volume method to solve both fluid and solid equations. Initially a fluid-only simulation was carried out on a single patient-based geometry and results from this simulation were compared with experimental results. There was good qualitative and quantitative agreement between the experimental and numerical results, suggesting that OpenFOAM is capable of predicting the main features of unsteady flow through a complex patient-based abdominal aortic aneurysm geometry. The intraluminal thrombus and arterial wall were then included, and solid stress and fluid-structure interaction simulations were performed on this, and two other patient-based abdominal aortic aneurysm geometries. It was found that the solid stress simulations resulted in an under-estimation of the maximum stress by up to 5.9% when compared with the fluid-structure interaction simulations. In the fluid-structure interaction simulations, flow induced pressure within the aneurysm was found to be up to 4.8% higher than the value of peak systolic pressure imposed in the solid stress simulations, which is likely to be the cause of the variation in the stress results. In comparing the results from the initial fluid-only simulation with results from the fluid-structure interaction simulation on the same patient, it was found that wall shear stress values varied by up to 35% between the two simulation methods. It was concluded that solid stress simulations are adequate to predict the maximum stress in an aneurysm wall, while fluid-structure interaction simulations should be performed if accurate prediction of the fluid wall shear stress is necessary. Therefore, the decision to perform fluid-structure interaction simulations should be based on the particular variables of interest in a given

  19. Exergy analysis of Portuguese municipal solid waste treatment via steam gasification

    International Nuclear Information System (INIS)

    Couto, Nuno; Silva, Valter; Monteiro, Eliseu; Rouboa, Abel

    2017-01-01

    Highlights: • Evaluation of Portuguese municipal solid waste gasification was conducted. • Previously studied biomass substrate was used as benchmark. • Numerical model built upon a reliable set of experimental runs was used. • Thermodynamic analysis on steam as gasifying agent was showed. • A CFD model was combined with RSM to optimize exergy efficiency. - Abstract: The presented study focuses on a thermodynamic analysis conducted on steam gasification of Portuguese municipal solid wastes (MSW). Current literature addressing this issue is extremely scarce due to the complexity in handling MSW’s heterogeneity. To fill this significant gap, a mathematical model built upon a reliable set of experimental runs from a semi-industrial gasifier was used to evaluate the effects of reactor temperature and steam-to-biomass ratio (SBR) on produced gas and tar content. Results from a previously studied biomass substrate were used as benchmark. Numerical results were validated with both experimental results and existing literature. Increase in gasification temperature led to a clear increase in both exergy values and exergy efficiency. On the other hand, increase in SBR led to a sharp increase in the exergy values when steam was first introduced, leading to relatively constant values when SBR was further increased. Regarding exergy efficiency, SBR led to a clear maximum value, which in the case of forest residues was found at SBR = 1, while for MSW at 1.5. In order to promote a more hydrogen-rich gas, data obtained from the numerical model was used to design an exergy efficiency optimization model based on the response surface method. Maximum hydrogen efficiency was found at 900 °C with a SBR of 1.5 for MSW and 1 for forest residues. Surprisingly, forest residues and MSW presented virtually the same maximum hydrogen efficiency.

  20. Exergy analysis of a combined heat and power plant with integrated lignocellulosic ethanol production

    International Nuclear Information System (INIS)

    Lythcke-Jørgensen, Christoffer; Haglind, Fredrik; Clausen, Lasse R.

    2014-01-01

    Highlights: • We model a system where lignocellulosic ethanol production is integrated with a combined heat and power (CHP) plant. • We conduct an exergy analysis for the ethanol production in six different system operation points. • Integrated operation, district heating (DH) production and low CHP loads all increase the exergy efficiency. • Separate operation has the largest negative impact on the exergy efficiency. • Operation is found to have a significant impact on the exergy efficiency of the ethanol production. - Abstract: Lignocellulosic ethanol production is often assumed integrated in polygeneration systems because of its energy intensive nature. The objective of this study is to investigate potential irreversibilities from such integration, and what impact it has on the efficiency of the integrated ethanol production. An exergy analysis is carried out for a modelled polygeneration system in which lignocellulosic ethanol production based on hydrothermal pretreatment is integrated in an existing combined heat and power (CHP) plant. The ethanol facility is driven by steam extracted from the CHP unit when feasible, and a gas boiler is used as back-up when integration is not possible. The system was evaluated according to six operation points that alternate on the following three different operation parameters: Load in the CHP unit, integrated versus separate operation, and inclusion of district heating production in the ethanol facility. The calculated standard exergy efficiency of the ethanol facility varied from 0.564 to 0.855, of which the highest was obtained for integrated operation at reduced CHP load and full district heating production in the ethanol facility, and the lowest for separate operation with zero district heating production in the ethanol facility. The results suggest that the efficiency of integrating lignocellulosic ethanol production in CHP plants is highly dependent on operation, and it is therefore suggested that the

  1. On the definition of exergy efficiencies for petroleum systems: Application to offshore oil and gas processing

    International Nuclear Information System (INIS)

    Nguyen, Tuong-Van; Voldsund, Mari; Elmegaard, Brian; Ertesvåg, Ivar Ståle; Kjelstrup, Signe

    2014-01-01

    Exergy-based efficiencies are measures of the thermodynamic perfection of systems and processes. A meaningful formulation of these performance criteria for petroleum systems is difficult because of (i) the high chemical exergy of hydrocarbons, (ii) the large variety of chemical components, and (iii) the differences in operating conditions between facilities. This work focuses on offshore processing plants, considering four oil platforms that differ by their working conditions and designs. Several approaches from the scientific literature for similar processes are presented and applied to the four cases. They showed a low sensitivity to performance improvements, gave inconsistent results, or favoured facilities operating under certain conditions. We suggest an alternative formulation, called the component-by-component exergy efficiency, which builds on the decomposition of the exergy flows at the level of the chemical compounds. It allows therefore for sound comparisons of separation systems, while it successfully evaluates their theoretical improvement potentials. The platform displaying the lowest efficiency (1.7%) is characterised by little pumping and compression works, at the opposite of the one displaying the highest performance (29.6%). A more realistic measure of the technical potential for improving these systems can be carried out by splitting further the exergy destruction into its avoidable and unavoidable parts. - Highlights: • Different exergy efficiency definitions for petroleum systems are reviewed. • These definitions are applied to four oil and gas platforms and are revealed to be inapplicable. • A new formulation, namely the component-by-component efficiency, is proposed. • The performance of the offshore platforms under study varies between 1.7% and 29.6%

  2. Solar and wind exergy potentials for Mars

    International Nuclear Information System (INIS)

    Delgado-Bonal, Alfonso; Martín-Torres, F. Javier; Vázquez-Martín, Sandra; Zorzano, María-Paz

    2016-01-01

    The energy requirements of the planetary exploration spacecrafts constrain the lifetime of the missions, their mobility and capabilities, and the number of instruments onboard. They are limiting factors in planetary exploration. Several missions to the surface of Mars have proven the feasibility and success of solar panels as energy source. The analysis of the exergy efficiency of the solar radiation has been carried out successfully on Earth, however, to date, there is not an extensive research regarding the thermodynamic exergy efficiency of in-situ renewable energy sources on Mars. In this paper, we analyse the obtainable energy (exergy) from solar radiation under Martian conditions. For this analysis we have used the surface environmental variables on Mars measured in-situ by the Rover Environmental Monitoring Station onboard the Curiosity rover and from satellite by the Thermal Emission Spectrometer instrument onboard the Mars Global Surveyor satellite mission. We evaluate the exergy efficiency from solar radiation on a global spatial scale using orbital data for a Martian year; and in a one single location in Mars (the Gale crater) but with an appreciable temporal resolution (1 h). Also, we analyse the wind energy as an alternative source of energy for Mars exploration and compare the results with those obtained on Earth. We study the viability of solar and wind energy station for the future exploration of Mars, showing that a small square solar cell of 0.30 m length could maintain a meteorological station on Mars. We conclude that the low density of the atmosphere of Mars is responsible of the low thermal exergy efficiency of solar panels. It also makes the use of wind energy uneffective. Finally, we provide insights for the development of new solar cells on Mars. - Highlights: • We analyse the exergy of solar radiation under Martian environment • Real data from in-situ instruments is used to determine the maximum efficiency of radiation • Wind

  3. On exergy analysis of industrial plants and significance of ambient temperature

    Energy Technology Data Exchange (ETDEWEB)

    Rian, Berit

    2011-07-01

    The exergy analysis has been a relatively mature theory for more than 30 years. However, it is not that developed in terms of procedures for optimizing systems, which partly explains why it is not that common. Misconceptions and prejudices, even among scientists, are also partly to blame.The main objective of this work was to contribute to the development of an understanding and methodology of the exergy analysis. The thesis was mainly based on three papers, two of which provided very different examples from existing industrial systems in Norway, thus showing the societal perspective in terms of resource utilization and thermodynamics. The last paper and the following investigation were limited to certain aspects of ambient conditions. Two Norwegian operational plants have been studied, one operative for close to 30 years (Kaarstoe steam production and distribution system), while the other has just started its expected 30 years of production (Snoehvit LNG plant). In addition to mapping the current operational status of these plants, the study of the Kaarstoe steam production and distribution system concluded that the potential for increasing the thermodynamic performance by rather cautious actions was significant, whereas the study of the Snoehvit LNG plant showed the considerable profit which the Arctic location provided in terms of reduced fuel consumption. The significance of the ambient temperature led to the study of systems with two ambient bodies (i.e. ambient water and ambient air) of different temperatures, here three different systems were investigated: A regenerative steam injection gas turbine (RSTIG), a simple Linde air liquefaction plant (Air Liq) and an air-source heat pump water heater (HPWH). In particular, the effect of the chosen environment on exergy analysis was negligible for RSTIG, modest for Air Liq and critical for HPWH. It was found that the amount of exergy received from the alternative ambient body, compared to the main exergy flow of

  4. Energy and Exergy Performances of Air-Based vs. Water-Based Heating and Cooling Systems: A Case Study of a Single-Family House

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

    2016-01-01

    Different indoor terminal units can be used to heat and cool indoor spaces. These terminal units mostly rely on convection and radiation heat transfer mechanisms but their relative ratios can vary significantly for air-based and water-based systems with implications on whole system performance, i...

  5. Exergy Steam Drying and Energy Integration

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Prem; Muenter, Claes (Exergy Engineering and Consulting, SE-417 55 Goeteborg (Sweden)). e-mail: verma@exergyse.com

    2008-10-15

    Exergy Steam Drying technology has existed for past 28 years and many new applications have been developed during this period. But during past few years the real benefits have been exploited in connection with bio-fuel production and energy integration. The steam dryer consists of a closed loop system, where the product is conveyed by superheated and pressurised carrier steam. The carrier steam is generated by the water vapours from the product being dried, and is indirectly superheated by another higher temperature energy source such as steam, flue gas, thermal oil etc. Besides the superior heat transfer advantages of using pressurised steam as a drying medium, the energy recovery is efficient and simple as the recovered energy (80-90%) is available in the form of steam. In some applications the product quality is significantly improved. Examples presented in this paper: Bio-Combine for pellets production: Through integration of the Exergy Steam Dryer for wood with a combined heat and power (CHP) plant, together with HP steam turbine, the excess carrier steam can be utilised for district heating and/or electrical power production in a condensing turbine. Bio-ethanol production: Both for first and second generation of ethanol can the Exergy process be integrated for treatment of raw material and by-products. Exergy Steam Dryer can dry the distillers dark grains and solubles (DDGS), wood, bagasse and lignin. Bio-diesel production: Oil containing seeds and fruits can be treated in order to improve both the quality of oil and animal feed protein, thus minimizing further oil processing costs and increasing the sales revenues. Sewage sludge as bio-mass: Municipal sewage sludge can be considered as a renewable bio-fuel. By drying and incineration, the combustion heat value of the sludge is sufficient for the drying process, generation of electrical energy and production of district heat. Keywords; Exergy, bio-fuel, bio-mass, pellets, bio-ethanol, biodiesel, bio

  6. Comparative performance analysis of low-temperature Organic Rankine Cycle (ORC) using pure and zeotropic working fluids

    International Nuclear Information System (INIS)

    Aghahosseini, S.; Dincer, I.

    2013-01-01

    In this paper, a comprehensive thermodynamic analysis of the low-grade heat source Organic Rankine Cycle (ORC) is conducted and the cycle performance is analyzed and compared for different pure and zeotropic-mixture working fluids. The comparative performance evaluation of the cycle using a combined energy and exergy analysis is carried out by sensitivity assessment of the cycle certain operating parameters such as efficiency, flow rate, irreversibility, and heat input requirement at various temperatures and pressures. The environmental characteristics of the working fluids such as toxicity, flammability, ODP and GWP are studied and the cycle CO 2 emission is compared with different fuel combustion systems. R123, R245fa, R600a, R134a, R407c, and R404a are considered as the potential working fluids. Results from this analysis provide valuable insight into selection of the most suitable working fluids for power generating application at different operating conditions with a minimal environmental impact. -- Highlights: ► Combined energy and exergy analysis is conducted for Organic Rankine Cycle. ► Comparative assessment is performed for different pure and zeotropic working fluids. ► Exergy and energy efficiency, cycle irreversibility, and required external heat are analyzed. ► Toxicity, flammability, ODP and GWP of considered working fluids are studied. ► Environmental benefits of the renewable/waste heat-based ORC are investigated

  7. Nature of macroeconomic equilibrium and driving force of economic cycles in the light of difference between money and exergy forms in cost estimations

    Energy Technology Data Exchange (ETDEWEB)

    Bandura, A.V. [National Politechnical Univ., Kiev (Ukraine); Brodianskii, V.M. [Moscow Power Engineering Inst. Technical Univ. (Russian Federation)

    1996-11-01

    The main problem of exergy application directly in economic analysis is to find valid correlation between money-based cost and exergy based one (including exergy expenses of labour) and to define exergy cost as an economic category among the existing traditional economic ones. The present report is aimed to search the way for this macroeconomic problems` solution. It is demonstrated that exergy-based cost can be recalculated in a monetary form using a coefficient, defined as a ratio between money supply and the total exergy of all natural resources involved in production process, i.e. as a ratio between monetary and exergy bases. The difference between `natural` and current prices (P) can be used directly both for general quantitative characteristics of an economic cycles driving force and for control of market relationship imperfection. It is shown that for the period of time with the positive P, that is, current price is lower than a `natural` one, the recoveries in business cycles are observed. For the period of time with the negative P, that is, current price is higher than a natural one, economic recessions are observed. The moment of time when P = 0 corresponds to the turning point of a business cycle. In such a way the possibility to predict the turning points of business cycles is demonstrated. 14 refs, 2 figs, 2 tabs

  8. Exergy Analysis of Operating Lignite Fired Thermal Power Plant

    Directory of Open Access Journals (Sweden)

    K. Murugesan

    2009-01-01

    Full Text Available The energy assessment must be made through the energy quantity as well as the quality. But the usual energy analysisevaluates the energy generally on its quantity only. However, the exergy analysis assesses the energy on quantity as well asthe quality. The aim of the exergy analysis is to identify the magnitudes and the locations of real energy losses, in order toimprove the existing systems, processes or components. The present paper deals with an exergy analysis performed on anoperating 50MWe unit of lignite fired steam power plant at Thermal Power Station-I, Neyveli Lignite Corporation Limited,Neyveli, Tamil Nadu, India. The exergy losses occurred in the various subsystems of the plant and their components havebeen calculated using the mass, energy and exergy balance equations. The distribution of the exergy losses in several plantcomponents during the real time plant running conditions has been assessed to locate the process irreversibility. The Firstlaw efficiency (energy efficiency and the Second law efficiency (exergy efficiency of the plant have also been calculated.The comparison between the energy losses and the exergy losses of the individual components of the plant shows that themaximum energy losses of 39% occur in the condenser, whereas the maximum exergy losses of 42.73% occur in the combustor.The real losses of energy which has a scope for the improvement are given as maximum exergy losses that occurredin the combustor.

  9. Energy and exergy analyses of the diffusion absorption refrigeration system

    International Nuclear Information System (INIS)

    Yıldız, Abdullah; Ersöz, Mustafa Ali

    2013-01-01

    This paper describes the thermodynamic analyses of a DAR (diffusion absorption refrigeration) cycle. The experimental apparatus is set up to an ammonia–water DAR cycle with helium as the auxiliary inert gas. A thermodynamic model including mass, energy and exergy balance equations are presented for each component of the DAR cycle and this model is then validated by comparison with experimental data. In the thermodynamic analyses, energy and exergy losses for each component of the system are quantified and illustrated. The systems' energy and exergy losses and efficiencies are investigated. The highest energy and exergy losses occur in the solution heat exchanger. The highest energy losses in the experimental and theoretical analyses are found 25.7090 W and 25.4788 W respectively, whereas those losses as to exergy are calculated 13.7933 W and 13.9976 W. Although the values of energy efficiencies obtained from both the model and experimental studies are calculated as 0.1858, those values, in terms of exergy efficiencies are found 0.0260 and 0.0356. - Highlights: • The diffusion absorption refrigerator system is designed manufactured and tested. • The energy and exergy analyses of the system are presented theoretically and experimentally. • The energy and exergy losses are investigated for each component of the system. • The highest energy and exergy losses occur in the solution heat exchanger. • The energy and the exergy performances are also calculated

  10. Second law-based thermodynamic analysis of water-lithium bromide absorption refrigeration system

    Energy Technology Data Exchange (ETDEWEB)

    Kilic, Muhsin [Department of Mechanical Engineering, Faculty of Engineering and Architecture, Uludag University, TR 16059, Bursa (Turkey)]. E-mail: mkilic@uludag.edu.tr; Kaynakli, Omer [Department of Mechanical Engineering, Faculty of Engineering and Architecture, Uludag University, TR 16059, Bursa (Turkey)

    2007-08-15

    In this study, the first and the second law of thermodynamics are used to analyze the performance of a single-stage water-lithium bromide absorption refrigeration system (ARS) when some working parameters are varied. A mathematical model based on the exergy method is introduced to evaluate the system performance, exergy loss of each component and total exergy loss of all the system components. Parameters connected with performance of the cycle-circulation ratio (CR), coefficient of performance (COP), Carnot coefficient of performance (COP{sub c} ), exergetic efficiency ({xi}) and efficiency ratio ({tau})-are calculated from the thermodynamic properties of the working fluids at various operating conditions. Using the developed model, the effect of main system temperatures on the performance parameters of the system, irreversibilities in the thermal process and non-dimensional exergy loss of each component are analyzed in detail. The results show that the performance of the ARS increases with increasing generator and evaporator temperatures, but decreases with increasing condenser and absorber temperatures. Exergy losses in the expansion valves, pump and heat exchangers, especially refrigerant heat exchanger, are small compared to other components. The highest exergy loss occurs in the generator regardless of operating conditions, which therefore makes the generator the most important component of the cycle.

  11. Second law-based thermodynamic analysis of water-lithium bromide absorption refrigeration system

    International Nuclear Information System (INIS)

    Kilic, Muhsin; Kaynakli, Omer

    2007-01-01

    In this study, the first and the second law of thermodynamics are used to analyze the performance of a single-stage water-lithium bromide absorption refrigeration system (ARS) when some working parameters are varied. A mathematical model based on the exergy method is introduced to evaluate the system performance, exergy loss of each component and total exergy loss of all the system components. Parameters connected with performance of the cycle-circulation ratio (CR), coefficient of performance (COP), Carnot coefficient of performance (COP c ), exergetic efficiency (ξ) and efficiency ratio (τ)-are calculated from the thermodynamic properties of the working fluids at various operating conditions. Using the developed model, the effect of main system temperatures on the performance parameters of the system, irreversibilities in the thermal process and non-dimensional exergy loss of each component are analyzed in detail. The results show that the performance of the ARS increases with increasing generator and evaporator temperatures, but decreases with increasing condenser and absorber temperatures. Exergy losses in the expansion valves, pump and heat exchangers, especially refrigerant heat exchanger, are small compared to other components. The highest exergy loss occurs in the generator regardless of operating conditions, which therefore makes the generator the most important component of the cycle

  12. Unsteady exergy destruction of the neuron under dynamic stress conditions

    International Nuclear Information System (INIS)

    Genc, S.; Sorguven, E.; Ozilgen, M.; Aksan Kurnaz, I.

    2013-01-01

    Just like all physical systems, biological systems also obey laws of thermodynamics, and as such the useful work potential of a biological system is its exergy. In some studies, exergy of living systems is considered with respect to work performance of humans in offices or buildings; however the exergy analysis of biochemical reactions in a cell as a closed system goes largely untouched. In this study, exergy analysis was applied to glucose metabolism of a model neuron, and dynamic exergy destructions were calculated for four different conditions, namely normoxia, hypoxia, glucose starvation and excess glucose. Our results showed that neuronal metabolism achieved a new steady state under each condition within 5 min. This dynamic model predicts that, both exergy destruction and work potential rates increase with increasing blood glucose concentration. The ratio of exergy destruction rate to work potential rate increases logarithmically with increasing blood glucose concentration. The neuronal metabolism is thus found to function in an efficient way and switches to lower exergy destruction under stress conditions such as glucose starvation. This behavior seen in this exergy analysis study confirms the assumption of minimum entropy production in living systems. - Highlights: • Unsteady exergy analysis of glucose metabolism of a model neuron is performed. • Dynamic exergy losses were calculated for four different conditions: normoxia, hypoxia, glucose starvation and excess glucose. • Neuronal metabolism achieved a new steady state under each condition within 5 min. • Both exergy loss and work potential rates increase with increasing blood glucose concentration. • Neuronal metabolism functions in an efficient way and switches to lower exergy loss under stress conditions

  13. An attempt to introduce dynamics into generalised exergy considerations

    International Nuclear Information System (INIS)

    Grubbstroem, Robert W.

    2007-01-01

    In previous research, the author developed a general abstract framework for the exergy content of a system of finite objects [Grubbstroem RW. Towards a generalized exergy concept. In: van Gool W, Bruggink JJC, editors. Energy and time in the economic and physical sciences. Amsterdam: North-Holland; 1985. p. 41-56]. Each such object is characterised by its initial extensive properties and has an inner energy written as a function of these properties. It was shown that if these objects were allowed to interact, there is a maximum amount of work that can be extracted from the system as a whole, and a general formula for this potential was provided. It was also shown that if one of the objects was allowed to be of infinite magnitude initially, taking on the role as an environment having constant intensive properties, then the formula provided took on the same form as the classical expression for exergy. As a side result, the theoretical considerations demonstrated that the second law of thermodynamics could be interpreted as the inner energy function being a (weakly) convex function of its arguments, when these are chosen as the extensive properties. Since exergy considerations are based on the principle that total entropy is conserved when extracting work, these processes would take an infinite time to complete. In the current paper, instead, a differential-equation approach is introduced to describe the interaction in finite time between given finite objects of a system. Differences in intensive properties between the objects provide a force enabling an exchange of energy and matter. An example of such an interaction is heat conduction. The resulting considerations explain how the power extracted from the system will be limited by the processes being required to perform within finite-time constraints. Applying finite-time processes, in which entropy necessarily is generated, leads to formulating a theory for a maximal power output from the system. It is shown that

  14. A net-zero building application and its role in exergy-aware local energy strategies for sustainability

    International Nuclear Information System (INIS)

    Kılkış, Şiir

    2012-01-01

    Highlights: ► Net-zero exergy targets are put forth for more energy-sufficient buildings and districts. ► A premier building that is the first LEED Platinum building in Turkey exemplifies this target. ► The building integrates low-exergy measures with PV/BIPV, CHP, GSHP, solar collectors and TES. ► Two districts in the south heating network of Stockholm are compared with this technology bundle. ► Net-zero exergy targets are related to a re-structuring of an exergy-aware energy value chain. - Abstract: Based on two case studies, this paper explores the nexus of exergy, net-zero targets, and sustainable cities as a means of analyzing the role of exergy-aware strategies at the building and district level. The first case study is a premier building in Ankara that is ready to meet the net-zero exergy target. It is also the first building in Turkey to receive the highest Platinum rating in Leadership in Energy and Environmental Design. A net-zero exergy building (NZEXB) is a building that has an annual sum of net-zero exergy transfer across the building-district boundary. This new target is made possible by lowered annual exergy consumption, (AEXC), and increased on-site production from a bundle of sustainable energy technologies. The modeled results of the building indicate that the reduced AEXC of 60 kW h/m 2 yr is met with on-site production of 62 kW h/m 2 yr. On-site production includes PV and building integrated PV, a micro-wind turbine, combined heat and power, GSHP, and solar collectors. Diversified thermal energy storage tanks further facilitate the exergy supply to meet with the exergy demand. The results of this case study provide key lessons to structure an energy value chain that is more aware of exergy, which are up-scalable to the district level when the bundle of sustainable energy technologies is zoomed out across a larger spatial area. These key lessons are then compared with the second case study of two districts in the south heating network

  15. Simulation based engineering in fluid flow design

    CERN Document Server

    Rao, J S

    2017-01-01

    This volume offers a tool for High Performance Computing (HPC). A brief historical background on the subject is first given. Fluid Statics dealing with Pressure in fluids at rest, Buoyancy and Basics of Thermodynamics are next presented. The Finite Volume Method, the most convenient process for HPC, is explained in one-dimensional approach to diffusion with convection and pressure velocity coupling. Adiabatic, isentropic and supersonic flows in quasi-one dimensional flows in axisymmetric nozzles is considered before applying CFD solutions. Though the theory is restricted to one-dimensional cases, three-dimensional CFD examples are also given. Lastly, nozzle flows with normal shocks are presented using turbulence models. Worked examples and exercises are given in each chapter. Fluids transport thermal energy for its conversion to kinetic energy, thus playing a major role that is central to all heat engines. With the advent of rotating machinery in the 20th century, Fluid Engineering was developed in the form o...

  16. On the Reference State for Exergy when Ambient Temperature Fluctuates

    OpenAIRE

    Michel Pons

    2009-01-01

    Exergy (availability) is the amount of mechanical work that could be produced by reversible processes. This notion is revisited in the case when ambient temperature fluctuates. Simple examples are first considered, and then a theoretical approach is developed. It results that the most reliable way for combining entropy and total energy into an exergy function is a linear combination where entropy is multiplied by a constant temperature. It results that ambient air has non-zero exergy, but tha...

  17. Theoretical analysis of the performance of different cooling strategies with the concept of cool exergy

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

    2016-01-01

    The whole chains of exergy flows for different cooling systems were compared. The effects of cooling demand (internal vs. external solar shading), space cooling method (floor cooling vs. air cooling with ventilation system), and the availability of a nearby natural heat sink (intake air for the v......The whole chains of exergy flows for different cooling systems were compared. The effects of cooling demand (internal vs. external solar shading), space cooling method (floor cooling vs. air cooling with ventilation system), and the availability of a nearby natural heat sink (intake air...... for the ventilation system being outdoor air vs. air from the crawl-space, and air-to-water heat pump vs. ground heat exchanger as cooling source) on system exergy performance were investigated. It is crucial to minimize the cooling demand because it is possible to use a wide range of heat sinks (ground, lake, sea......-water, etc.) and indoor terminal units, only with a minimized demand. The water-based floor cooling system performed better than the air-based cooling system; when an air-to-water heat pump was used as the cooling source, the required exergy input was 28% smaller for the floor cooling system. The auxiliary...

  18. Modeling and Exergy Analysis of District Cooling

    DEFF Research Database (Denmark)

    Nguyen, Chan

    in the gas cooler, pinch temperature in the evaporator and effectiveness of the IHX. These results are complemented by the exergy analysis, where the exergy destruction ratio of the CO2 system’s component is found. Heat recovery from vapour compression heat pumps has been investigated. The heat is to be used...... consists of a combined heat and power (CHP) plant with a separate refrigeration plant, where its condenser heat is rejected to the environment. The recovery system consists of the same CHP plant but with a heat pump, where the condensation heat is recovered. Five different refrigerants (R717, R600a, R290...... and surrounding temperature has been carried out. It has been demonstrated that the two methods yield significantly different results. Energy costing prices the unit cost of heating and cooling equally independent of the quality of the heat transfer, and it tends to overprice the cost of cooling in an irrational...

  19. An exergy approach to efficiency evaluation of desalination

    KAUST Repository

    Ng, Kim Choon

    2017-05-02

    This paper presents an evaluation process efficiency based on the consumption of primary energy for all types of practical desalination methods available hitherto. The conventional performance ratio has, thus far, been defined with respect to the consumption of derived energy, such as the electricity or steam, which are susceptible to the conversion losses of power plants and boilers that burned the input primary fuels. As derived energies are usually expressed by the units, either kWh or Joules, these units cannot differentiate the grade of energy supplied to the processes accurately. In this paper, the specific energy consumption is revisited for the efficacy of all large-scale desalination plants. In today\\'s combined production of electricity and desalinated water, accomplished with advanced cogeneration concept, the input exergy of fuels is utilized optimally and efficiently in a temperature cascaded manner. By discerning the exergy destruction successively in the turbines and desalination processes, the relative contribution of primary energy to the processes can be accurately apportioned to the input primary energy. Although efficiency is not a law of thermodynamics, however, a common platform for expressing the figures of merit explicit to the efficacy of desalination processes can be developed meaningfully that has the thermodynamic rigor up to the ideal or thermodynamic limit of seawater desalination for all scientists and engineers to aspire to.

  20. An exergy approach to efficiency evaluation of desalination

    Science.gov (United States)

    Ng, Kim Choon; Shahzad, Muhammad Wakil; Son, Hyuk Soo; Hamed, Osman A.

    2017-05-01

    This paper presents an evaluation process efficiency based on the consumption of primary energy for all types of practical desalination methods available hitherto. The conventional performance ratio has, thus far, been defined with respect to the consumption of derived energy, such as the electricity or steam, which are susceptible to the conversion losses of power plants and boilers that burned the input primary fuels. As derived energies are usually expressed by the units, either kWh or Joules, these units cannot differentiate the grade of energy supplied to the processes accurately. In this paper, the specific energy consumption is revisited for the efficacy of all large-scale desalination plants. In today's combined production of electricity and desalinated water, accomplished with advanced cogeneration concept, the input exergy of fuels is utilized optimally and efficiently in a temperature cascaded manner. By discerning the exergy destruction successively in the turbines and desalination processes, the relative contribution of primary energy to the processes can be accurately apportioned to the input primary energy. Although efficiency is not a law of thermodynamics, however, a common platform for expressing the figures of merit explicit to the efficacy of desalination processes can be developed meaningfully that has the thermodynamic rigor up to the ideal or thermodynamic limit of seawater desalination for all scientists and engineers to aspire to.

  1. Microscope-Based Fluid Physics Experiments in the Fluids and Combustion Facility on ISS

    Science.gov (United States)

    Doherty, Michael P.; Motil, Susan M.; Snead, John H.; Malarik, Diane C.

    2000-01-01

    At the NASA Glenn Research Center, the Microgravity Science Program is planning to conduct a large number of experiments on the International Space Station in both the Fluid Physics and Combustion Science disciplines, and is developing flight experiment hardware for use within the International Space Station's Fluids and Combustion Facility. Four fluids physics experiments that require an optical microscope will be sequentially conducted within a subrack payload to the Fluids Integrated Rack of the Fluids and Combustion Facility called the Light Microscopy Module, which will provide the containment, changeout, and diagnostic capabilities to perform the experiments. The Light Microscopy Module is planned as a fully remotely controllable on-orbit microscope facility, allowing flexible scheduling and control of experiments within International Space Station resources. This paper will focus on the four microscope-based experiments, specifically, their objectives and the sample cell and instrument hardware to accommodate their requirements.

  2. Multidimensional modeling of the effect of Exhaust Gas Recirculation (EGR) on exergy terms in an HCCI engine fueled with a mixture of natural gas and diesel

    International Nuclear Information System (INIS)

    Jafarmadar, Samad; Nemati, Peyman; Khodaie, Rana

    2015-01-01

    Highlights: • The exergy efficiency decreases by 41.3%. • The irreversibility increases by 46.80%. • The cumulative heat loss exergy decreases by 68.10%. • The cumulative work exergy decreases by 63.4%. • The exhaust losses exergy increases by 28.79%. - Abstract: One of the most important issues in HCCI engines is auto-ignition timing control. EGR introduction into intake charge can be a method to control combustion phasing and its duration. In the current study, a FORTRAN-based code which includes 10 species (O_2, N_2, H_2O, CO_2, CO, H_2, OH, O, N, NO) associated with combustion products was employed to study the exergy analysis in a dual fuel (natural gas + diesel) HCCI engine at four EGR (exhaust gas recirculation) mass fractions (0%, 10%, 20%, and 30%) while the diesel fuel amount was held constant. In order to achieve this task, a 3-D CFD code was employed to model the energy balance during a closed cycle of running engine simulation. Moreover, an efficient Extend Coherent Flame Model-Three Zone model (ECFM-3Z) method was employed to analyze the combustion process. With crank positions at different EGR mass fractions, the exergy terms were identified and calculated separately. It was found that as EGR mass fraction increased from 0% to 30% (in 10% increment steps), exergy efficiency decreased from 48.9% to 28.7%. Furthermore, with the change in EGR mass fraction, the cumulative heat loss exergy decreased from 10.1% to 5.64% of mixture fuels chemical exergy.

  3. Exergy Analysis of a Subcritical Reheat Steam Power Plant with Regression Modeling and Optimization

    Directory of Open Access Journals (Sweden)

    MUHIB ALI RAJPER

    2016-07-01

    Full Text Available In this paper, exergy analysis of a 210 MW SPP (Steam Power Plant is performed. Firstly, the plant is modeled and validated, followed by a parametric study to show the effects of various operating parameters on the performance parameters. The net power output, energy efficiency, and exergy efficiency are taken as the performance parameters, while the condenser pressure, main steam pressure, bled steam pressures, main steam temperature, and reheat steam temperature isnominated as the operating parameters. Moreover, multiple polynomial regression models are developed to correlate each performance parameter with the operating parameters. The performance is then optimizedby using Direct-searchmethod. According to the results, the net power output, energy efficiency, and exergy efficiency are calculated as 186.5 MW, 31.37 and 30.41%, respectively under normal operating conditions as a base case. The condenser is a major contributor towards the energy loss, followed by the boiler, whereas the highest irreversibilities occur in the boiler and turbine. According to the parametric study, variation in the operating parameters greatly influences the performance parameters. The regression models have appeared to be a good estimator of the performance parameters. The optimum net power output, energy efficiency and exergy efficiency are obtained as 227.6 MW, 37.4 and 36.4, respectively, which have been calculated along with optimal values of selected operating parameters.

  4. Exergy analysis of building integrated semitransparent photovoltaic thermal (BiSPVT system

    Directory of Open Access Journals (Sweden)

    Neha Gupta

    2017-02-01

    Full Text Available In this paper, an exergy analysis of building integrated semitransparent photovoltaic thermal (BiSPVT system has been carried out. In the proposed system, the room below building integrated semitransparent photovoltaic thermal system has been considered as an air-conditioned (constant room temperature. Energy balance equation for each components namely semitransparent photovoltaic roof, floor and room air have been given. Based on energy balance, an analytical expression for room air, solar cell and room floor temperatures have been derived along with solar cell electrical efficiency. Further by considering the day lighting parameters, an overall exergy of the proposed system has been derived for different number of air change between the room and ambient air. It has been observed that there is reduction in room air and solar cell temperatures with an increase of number of air changes. However, solar cell electrical efficiency increases with decrease in temperature of solar cell. Further, it is found that an electrical power and illumination inside the room are more dominating in comparison with thermal exergy. An increase of 1.15% in an overall exergy is observed for the number of air changes varies from 0 to 4. Experimental validation of theoretical model has also been carried out.

  5. Scanning Probe Microscope-Based Fluid Dispensing

    NARCIS (Netherlands)

    Ghatkesar, M.K.; Perez Garza, H.H.; Heuck, F.; Staufer, U.

    2014-01-01

    Advances in micro and nano fabrication technologies have enabled fabrication of smaller and more sensitive devices for applications not only in solid-state physics but also in medicine and biology. The demand for devices that can precisely transport material, specifically fluids are continuously

  6. Numerical study of shear thickening fluid with discrete particles embedded in a base fluid

    Directory of Open Access Journals (Sweden)

    W Zhu

    2016-09-01

    Full Text Available The Shear Thickening Fluid (STF is a dilatant material, which displays non-Newtonian characteristics in its unique ability to transit from a low viscosity fluid to a high viscosity fluid. The research performed investigates the STF behavior by modeling and simulation of the interaction between the base flow and embedded rigid particles when subjected to shear stress. The model considered the Lagrangian description of the rigid particles and the Eulerian description of fluid flow. The numerical analysis investigated key parameters such as applied flow acceleration, particle distribution and arrangement, volume concentration of particles, particle size, shape and their behavior in a Newtonian and non-Newtonian fluid base. The fluid-particle interaction model showed that the arrangement, size, shape and volume concentration of the particles had a significant effect on the behavior of the STF. Although non-conclusive, the addition of particles in non-Newtonian fluids showed a promising trend of improved shear thickening effects at high shear strain rates.

  7. Energy and exergy analysis of integrated system of ammonia–water Kalina–Rankine cycle

    International Nuclear Information System (INIS)

    Chen, Yaping; Guo, Zhanwei; Wu, Jiafeng; Zhang, Zhi; Hua, Junye

    2015-01-01

    The integrated system of AWKRC (ammonia–water Kalina–Rankine cycle) is a novel cycle operated on KC (Kalina cycle) for power generation in non-heating seasons and on AWRC (ammonia–water Rankine cycle) for cogeneration of power and heating water in winter. The influences of inlet temperatures of both heat resource and cooling water on system efficiencies were analyzed based on the first law and the second law of thermodynamics. The calculation is based on following conditions that the heat resource temperature keeps 300 °C, the cooling water temperature for the KC or AWRC is respectively 25 °C or 15 °C; and the temperatures of heating water and backwater are respectively 90 °C and 40 °C. The results show that the evaluation indexes of the power recovery efficiency and the exergy efficiency of KC were respectively 18.2% and 41.9%, while the composite power recovery efficiency and the composite exergy efficiency of AWRC are respectively 21.1% and 43.0% accounting both power and equivalent power of cogenerated heating capacity, including 54.5% heating recovery ratio or 12.4% heating water exergy efficiency. The inventory flow diagrams of both energy and exergy gains and losses of the components operating on KC or AWRC are also demonstrated. - Highlights: • An integrated system of AWKRC (ammonia–water Kalina–Rankine cycle) is investigated. • NH_3–H_2O Rankine cycle is operated for cogenerating power and heating-water in winter. • Heating water with 90 °C and capacity of 54% total reclaimed heat load is cogenerated. • Kalina cycle is operated for power generation in other seasons with high efficiency. • Energy and exergy analysis draw similar results in optimizing the system parameters.

  8. Energy and exergy recovery in a natural gas compressor station – A technical and economic analysis

    International Nuclear Information System (INIS)

    Kostowski, Wojciech J.; Kalina, Jacek; Bargiel, Paweł; Szufleński, Paweł

    2015-01-01

    Highlights: • Energy and exergy flow in a natural gas compressor station. • Operational efficiency only 18.3% vs. 35.1% nominal. • 3 energy/exergy recovery systems proposed. • Up to 168.9 GW h/y electricity and 6.5 GW h/y heat recoverable. • Legal obstacles: operators not allowed to produce electricity. - Abstract: The paper presents possible solutions to improve the thermodynamic performance of a natural gas compressor station equipped with various type of compressor units and operated at part-load conditions. A method for setting a simplified energy and exergy balance based on the available metering information has been presented. For a case study plant, it has been demonstrated that the current part-load operation leads to a significant decrease in energy and exergy efficiency compared to the nominal state of machinery. Three alternative improvement strategies have been proposed: (1) installation of a heat recovery hot water generator for covering the existing heat demand of the plant; (2) installation of a heat recovery thermal oil heater for covering the existing heat demand and driving an organic Rankine cycle (ORC) for electricity generation; (3) installation of a heat recovery thermal oil heater with and ORC and gas expanders for switching into full-load operation of the gas turbine unit. Energy and exergy performance of the proposed strategies as well as their economic feasibility have been analyzed. The second scenario involving an ORC unit provides the highest local energy savings, however, its economic feasibility is not achieved under the current part-load operating conditions. A hypothetic scenario of the same station operated at full-load due to an increased gas transmission capacity demonstrate the economic feasibility (possible under optimistic price conditions). Finally, it has been shown that the possibility of waste energy recovery from natural gas transmission systems (in particular, from compressor stations) depends on legal

  9. Addressing Different Approaches for Evaluating Low-Exergy Communities

    NARCIS (Netherlands)

    Jansen, S.C.; Meggers, Forrest; Heiselberg, Per Kvols

    2016-01-01

    The IEA Annex 64 focusing on low-ex communities aims at the improvement of energy conversion chains on a community scale, using exergy analysis as the primary evaluation mode. Within this Annex the participants discuss important aspects and available methods for energy and exergy assessment as well

  10. Comparison between exergy and energy analysis for biodiesel production

    International Nuclear Information System (INIS)

    Amelio, A.; Van de Voorde, T.; Creemers, C.; Degrève, J.; Darvishmanesh, S.; Luis, P.; Van der Bruggen, B.

    2016-01-01

    This study investigates the exergy concept for use in chemical engineering applications, and compares the energy and exergy methodology for the production process of biodiesel. A process for biodiesel production was suggested and simulated in view of the energy and exergy analysis. A method was developed to implement the exergy concept in Aspen Plus 7.3. A comparison between the energy and the exergy approach reveals that the concepts have similarities but also some differences. In the exergy study, the reaction section has the largest losses whereas in the energy study separation steps are the most important. An optimization, using both concepts, was carried out using the same parameters. The optimized results were different depending on the objective function. It was concluded that exergy analysis is crucial during the design or redesign step in order to investigate thermodynamic efficiencies in each part of the process. - Highlights: • New flowsheet for the production of biodiesel simulated with Aspen Plus. • Calculation of the exergetic costs and several interesting indexes. • Comparison of exergy and energy analysis for the process studied.

  11. Agarwood Waste as A New Fluid Loss Control Agent in Water-based Drilling Fluid

    Directory of Open Access Journals (Sweden)

    Azlinda Azizi

    2013-10-01

    Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 Agarwood has been used widely in various ways, including traditional medicine and art. The usage of agarwood has grown broader in modern times include in therapeutic medicines and perfumery. In this paper the agarwood waste has been explored to be used as a fluid loss control agent to control fluid loss without affecting the drilling fluid rheological properties which are density, pH, viscosity, yield point and gel strength. Agarwood waste was used as an additive in the drilling fluid system due to its unique characteristic. Rheological and filtration measurements were performed on the formulated water-based drilling fluid. Formulations of a base solution of fresh water, sodium hydroxide, bentonite, barite, and xanthan gum were presented. The performance of the agarwood waste as the fluid loss control agent was compared with based fluid formulation and water-based drilling fluid with treating with conventional fluid loss control agent (starch. The filtrate volume of drilling fluid with agarwood waste was about 13 ml while for drilling fluid with conventional fluid loss control agent, starch gave 12 ml of filtrate volume after undergoing filtration test by using LPLT filter press. The performance of drilling fluid with agarwood was efficient as drilling fluid with starch. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso

  12. Proposing a novel combined cycle for optimal exergy recovery of liquefied natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Salimpour, M.R.; Zahedi, M.A. [Isfahan University of Technology (Iran, Islamic Republic of). Department of Mechanical Engineering

    2012-08-15

    The effective utilization of the cryogenic exergy associated with liquefied natural gas (LNG) vaporization is important. In this paper, a novel combined power cycle is proposed which utilizes LNG in different ways to enhance the power generation of a power plant. In addition to the direct expansion in the appropriate expander, LNG is used as a low-temperature heat sink for a middle-pressure gas cycle which uses nitrogen as working fluid. Also, LNG is used to cool the inlet air of an open Brayton gas turbine cycle. These measures are accomplished to improve the exergy recovery of LNG. In order to analyze the performance of the system, the influence of several key parameters such as pressure ratio of LNG turbine, ratio of the mass flow rate of LNG to the mass flow rate of air, pressure ratio of different compressors, LNG pressure and inlet pressure of nitrogen compressor, on the thermal efficiency and exergy efficiency of the offered cycle is investigated. Finally, the proposed combined cycle is optimized on the basis of first and second laws of thermodynamics. (orig.)

  13. The correlation of energy with entropy and exergy; Die Vernetzung der Energie mit Entropie und Exergie

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Gernot (Dr. Gernot Weber, Energie-Gebaeudetechnik, Kleinostheim)

    2011-07-01

    Thermodynamics generally is regarded as one of the most difficult fields of knowledge. This may be particularly due to the difficulties and due to the often very complicated described correlations between the terms energy, entropy and exergy in the technical literature. The contribution under consideration tries to explain these correlations to the (scientifically trained) technically interested readers understandable.

  14. Energy and Exergy Analysis of the Danish Industry Sector

    DEFF Research Database (Denmark)

    Bühler, Fabian; Nguyen, Tuong-Van; Elmegaard, Brian

    2015-01-01

    % to 56% in 2012. Industries with high-temperature processes, such as the cement and metal production sectors, present the highest exergy efficiencies but the lowest energy ones. The opposite conclusion is drawn for the food, paper and chemical industries. The exergy losses, which indicate the potential......A detailed analysis of the Danish industry is presented in this paper using the energy, exergy and embodied exergy methods. The 22 most energy-intensive process industries, which represent about 80% of the total primary energy use of the industry, were modelled and analysed in details for the years...... is not seen with the embodied exergy efficiency, which remains at around 29% for the Danish industry. This analysis shows that there are still large potentials to recover waste heat in most Danish industrial sectors and thus to increase their efficiencies....

  15. Energy and exergy analyses of solar drying process of pistachio

    International Nuclear Information System (INIS)

    Midilli, A.; Kucuk, H.

    2003-01-01

    This paper is concerned with the energy and exergy analyses of the drying process of shelled and unshelled pistachios using a solar drying cabinet. Using the first law of thermodynamics, energy analysis was carried to estimate the amounts of energy gained from solar air collectors and the ratios of energy utilization. However, exergy analysis was accomplished to determine the location, type, and magnitude of exergy losses during the solar drying process by applying the second law of thermodynamics. It was deduced that the exergy losses took place mostly in the 15th shelf where the available energy was less utilized. Moreover, the shelled and unshelled pistachios are sufficiently dried in the ranges between 40 and 60 deg. C and 37 and 62% of relative humidity at 1.23 m s -1 of drying air velocity in 6 h despite the exergy losses of 0.15-3.08 kJ kg -1

  16. Energy and exergy analyses of solar drying process of pistachio

    Energy Technology Data Exchange (ETDEWEB)

    Midilli, A [University of Nigde (Turkey). Dept. of Mechanical Engineering; Kucuk, H [Karadeniz Technical Univ., Trabzon (Turkey). Dept. of Mechanical Engineering

    2003-05-01

    This paper is concerned with the energy and exergy analyses of the drying process of shelled and unshelled pistachios using a solar drying cabinet. Using the first law of thermodynamics, energy analysis was carried to estimate the amounts of energy gained from solar air collectors and the ratios of energy utilization. However, exergy analysis was accomplished to determine the location, type, and magnitude of exergy losses during the solar drying process by applying the second law of thermodynamics. It was deduced that the exergy losses took place mostly in the 15th shelf where the available energy was less utilized. Moreover, the shelled and unshelled pistachios are sufficiently dried in the ranges between 40 and 60{sup o}C and 37 and 62% of relative humidity at 1.23 m s{sup -1} of drying air velocity in 6 h despite the exergy losses of 0.15-3.08 kJ kg{sup -1}. (Author)

  17. ENERGY AND EXERGY ANALYSIS OF A POWDER DETERGENT UNIT

    International Nuclear Information System (INIS)

    G. Bektas; F. Balkan

    2008-01-01

    In the recent years, there is a growing interest on minimization of energy utilization in various plants and thereby improving the performance. As an efficient tool for examining the processes, the exergy analysis gains importance. In the present work, the application of exergy analysis to powder detergent unit of a powder detergent production plant located at Izmir, Turkey were performed y using actual plant operational data. Also the energy analyses were considered for comparison. Although there are a number of energy and exergy analyses in various areas of industry, this study will be likely the first one for powder detergent production. The energy and exergy efficiencies of the equipments were calculated and it was concluded that according to the overall balance around the unit, the energy efficiency was 0.76 and the exergy efficiency was 0.40

  18. ENERGY AND EXERGY ANALYSIS OF A POWDER DETERGENT UNIT

    Energy Technology Data Exchange (ETDEWEB)

    G. Bektas; F. Balkan [Ege University, Chemical Engineering Department, Izmir (Turkey)

    2008-09-30

    In the recent years, there is a growing interest on minimization of energy utilization in various plants and thereby improving the performance. As an efficient tool for examining the processes, the exergy analysis gains importance. In the present work, the application of exergy analysis to powder detergent unit of a powder detergent production plant located at Izmir, Turkey were performed y using actual plant operational data. Also the energy analyses were considered for comparison. Although there are a number of energy and exergy analyses in various areas of industry, this study will be likely the first one for powder detergent production. The energy and exergy efficiencies of the equipments were calculated and it was concluded that according to the overall balance around the unit, the energy efficiency was 0.76 and the exergy efficiency was 0.40.

  19. Possibilities and consequences of the Total Cumulative Exergy Loss method in improving the sustainability of power generation

    International Nuclear Information System (INIS)

    Stougie, Lydia; Kooi, Hedzer J. van der

    2016-01-01

    Highlights: • The TCExL method can be applied to all kinds of technological systems. • All exergy losses during the lifetime of a technological system are considered. • The results of the TCExL method are independent of time and weighting factors. • Applying the TCExL method can improve the sustainability of power generation. • The system with the lowest TCExL score is not always economically favourable. - Abstract: It is difficult to decide which power generation system is the most sustainable when environmental, economic and social sustainability aspects are taken into account. Problems with conventional environmental sustainability assessment methods are that no consensus exists about the applied models and weighting factors and that exergy losses are not considered. Economic sustainability assessment methods do not lead to results that are independent of time because they are influenced by market developments, while social sustainability assessment methods suffer from the availability and qualitative or semi-quantitative nature of data. Existing exergy analysis methods do not take into account all exergy losses and/or are extended with factors or equations that are not commonly accepted. The new Total Cumulative Exergy Loss (TCExL) method is based on fundamental thermodynamic equations and takes into account all exergy losses caused by a technological system during its life cycle, i.e. internal exergy losses, exergy losses caused by emission abatement and exergy losses related to land use. The development of the TCExL method is presented as well as the application of this method and environmental, economic and social sustainability assessment methods to two case studies: power generation in combination with LNG evaporation and Fossil versus renewable energy sources for power generation. According to the results of the assessments, large differences exist between the environmental sustainability assessment and TCExL methods in the sense that different

  20. Exergy analysis and parameter study on a novel auto-cascade Rankine cycle

    International Nuclear Information System (INIS)

    Bao, Junjiang; Zhao, Li

    2012-01-01

    A novel auto-cascade Rankine cycle (ARC) is proposed to reduce thermodynamics irreversibility and improve energy utilization. Like the Kalina cycle, the working fluid for the ARC is zeotropic mixture, which can improve the system efficiency due to the temperature slip that zeotropic mixtures exhibit during phase change. Unlike the Kalina cycle, two expanders are included in the ARC rather than a expander and a throttling valve in the Kalina cycle, which means more work can be obtained. Using the exhaust gas as the heat source and water as the heat sink, a program is written by Matlab 2010a to carry out exergy analysis and parameter study on the ARC. Results show that the R245fa mass fraction in the primary circuit exists an optimum value with respect to the minimum total cycle irreversibility. The largest exergy loss occurs in evaporator, followed by the superheater, condenser, regenerator and IHE (Internal heat exchanger). As the R245fa mass fraction increases, the exergy losses of different components vary diversely. With the evaporation pressure rises, the total cycle irreversibility decreases and work output increases. Separator temperature has a greater influence on the system performance than superheating temperature. Compared with ORC (organic Rankine cycle) and Kalina cycle in the literature, the ARC has proven to be thermodynamically better. -- Highlights: ► We have proposed a novel auto-cascade Rankine cycle (ARC) system. ► The zeotropic mixture Isopentane/R245fa is employed in this system. ► Exergy analysis and parameter study on the ARC are presented. ► Compared with ORC and Kalina cycle in the literature, the ARC has proven to be thermodynamically better.

  1. Exergy recovery during LNG regasification: Electric energy production - Part two

    International Nuclear Information System (INIS)

    Dispenza, Celidonio; Dispenza, Giorgio; Rocca, Vincenzo La; Panno, Giuseppe

    2009-01-01

    In liquefied natural gas (LNG) regasification facilities, for exergy recovery during regasification, an option could be the production of electric energy recovering the energy available as cold. In a previous paper, the authors propose an innovative process which uses a cryogenic stream of LNG during regasification as a cold source in an improved combined heat and power (CHP) plant. Considering the LNG regasification projects in progress all over the World, an appropriate design option could be based on a modular unit having a mean regasification capacity of 2 x 10 9 standard cubic meters/year. This paper deals with the results of feasibility studies, developed by the authors at DREAM in the context of a research program, on ventures based on thermodynamic and economic analysis of improved CHP cycles and related innovative technology which demonstrate the suitability of the proposal

  2. An Efficient Sleepy Algorithm for Particle-Based Fluids

    Directory of Open Access Journals (Sweden)

    Xiao Nie

    2014-01-01

    Full Text Available We present a novel Smoothed Particle Hydrodynamics (SPH based algorithm for efficiently simulating compressible and weakly compressible particle fluids. Prior particle-based methods simulate all fluid particles; however, in many cases some particles appearing to be at rest can be safely ignored without notably affecting the fluid flow behavior. To identify these particles, a novel sleepy strategy is introduced. By utilizing this strategy, only a portion of the fluid particles requires computational resources; thus an obvious performance gain can be achieved. In addition, in order to resolve unphysical clumping issue due to tensile instability in SPH based methods, a new artificial repulsive force is provided. We demonstrate that our approach can be easily integrated with existing SPH based methods to improve the efficiency without sacrificing visual quality.

  3. The Tenuous Use of Exergy as a Measure of Resource Value or Waste Impact

    Directory of Open Access Journals (Sweden)

    Roydon A. Fraser

    2009-12-01

    Full Text Available Exergy is a thermodynamic concept that has been widely promoted for assessing and improving sustainability, notably in the characterization of resources and wastes. Despite having many notable benefits, exergy is often misused by authors who tend to apply it as an intrinsic characteristic of an object (i.e., as a static thermodynamic variable. Using both theoretical and empirical evidence the authors present five key limitations that must be overcome before exergy can be applied to characterize objects: (1 the incompatibility between exergy quality and resource quality; (2 the inability of exergy to characterize non work-producing resources via the concentration exergy; (3 the constraints placed on the derivation of exergy; (4 problems with the exergy reference environment; and (5 the multiple perspectives applied to exergy analysis. Until the limitations are addressed, exergy should only be used for its original purpose as a decision making tool for engineering systems analysis.

  4. Mechanism of chain formation in nanofluid based MR fluids

    International Nuclear Information System (INIS)

    Patel, Rajesh

    2011-01-01

    Mechanism of structure formation in bidispersed colloids is important for its physical and optical properties. It is microscopically observed that the mechanism of chain formation in magnetic nanofluid based magnetorheological (MR) fluid is quite different from that in the conventional MR fluid. Under the application of magnetic field the magnetic nanoparticles are filled inside the structural microcavities formed due to the association of large magnetic particles, and some of the magnetic nanoparticles are attached at the end of the chains formed by the large particles. The dipolar energy of the large particles in a magnetic nanofluid matrix becomes effective magnetic permeability (μ eff ) times smaller than that of the neutral medium. Inclusion of magnetic nanoparticles (∼10 nm) with large magnetic particles (∼3-5 μm) restricts the aggregation of large particles, which causes the field induced phase separation in MR fluids. Hence, nanofluid based MR fluids are more stable than conventional MR fluids, which subsequently increase their application potentiality. - Research highlights: → In bidispersed magnetic colloids nanoparticles are attached at the end of the chains formed by the large particles. → Inclusion of magnetic nanoparticles (∼10 nm) with large magnetic particles (∼3-5 m) restricts the aggregation of large particles. → Nanofluid based MR fluids are more stable than conventional MR fluids.

  5. Exergy efficient production, storage and distribution of solar energy

    Energy Technology Data Exchange (ETDEWEB)

    Sandnes, Bjoernar

    2003-07-01

    There are two main themes in this thesis. 1) Exergy efficient utilization of solar energy, where the introduction of alternative technologies such as photovoltaic/thermal collectors and phase change energy storage in a low temperature solar system is investigated. 2) The possibility of storing thermal energy in supercooled liquids is investigated. The introductory chapters introduce the concept of exergy, and focus on the use of solar heat as an inherently low quality source for covering low quality demands associated with space heating and hot water. The different stages of solar energy production, storage, and distribution of heat is discussed, with emphasis on exergy relevant issues. With the low temperature solar heating system as background, the introduction of some additional technologies that are investigated. A section of this thesis presents a study of a small scale PV/T collector as a possible component in a low temperature system. In another section the instrumentation that has been built for studies of full-size PV and thermal systems is described, and the possibility of using the PV unit outputs as parameters for controlling the thermal system operation is briefly discussed. It is suggested that the design of the PV/T unit in terms of whether priority should be given to electricity or heat production should be based on how consumption of high quality auxiliary energy is minimized, and not on adding up the combined exergy which is being produced. Solar combisystems require larger heat storage capacities compared to the more common solar hot water systems. Increased volumetric heat storage capacity can be achieved by latent heat storage systems where thermal energy is stored as heat of fusion in phase change materials (PCMs). A section presents a study where spherically encapsulated PCM is incorporated in a solar heat store. Solar combisystems are often complex, and have a relatively large number of interacting components. Another section describes a

  6. Energy and exergy analyses of electrolytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, M A [Ryerson Polytechnic Univ., Toronto, ON (Canada). Dept. of Mechanical Engineering

    1995-07-01

    The thermodynamic performance is investigated of a water-electrolysis process for producing hydrogen, based on current-technology equipment. Both energy and exergy analyses are used. Three cases are considered in which the principal driving energy inputs are (i) electricity, (ii) the high-temperature heat used to generate the electricity, and (iii) the heat source used to produce the high-temperature heat. The nature of the heat source (e.g.) fossil fuel, nuclear fuel, solar energy, (etc.) is left as general as possible. The analyses indicate that, when the main driving input is the hypothetical heat source, the principal thermodynamic losses are associated with water splitting, electricity generation and heat production; the losses are mainly due to the irreversibilities associated with converting a heat source to heat, and heat transfer across large temperature differences. The losses associated with the waste heat in used cooling water, because of its low quality, are not as significant as energy analysis indicates. (Author)

  7. Energy and exergy analysis of the turbo-generators and steam turbine for the main feed water pump drive on LNG carrier

    International Nuclear Information System (INIS)

    Mrzljak, Vedran; Poljak, Igor; Mrakovčić, Tomislav

    2017-01-01

    Highlights: • Two low-power steam turbines in the LNG carrier propulsion plant were investigated. • Energy and exergy efficiencies of both steam turbines vary between 46% and 62%. • The ambient temperature has a low impact on exergy efficiency of analyzed turbines. • The maximum efficiencies area of both turbines was investigated. • A method for increasing the turbo-generator efficiencies by 1–3% is presented. - Abstract: Nowadays, marine propulsion systems are mainly based on internal combustion diesel engines. Despite this fact, a number of LNG carriers have steam propulsion plants. In such plants, steam turbines are used not only for ship propulsion, but also for electrical power generation and main feed water pump drive. Marine turbo-generators and steam turbine for the main feed water pump drive were investigated on the analyzed LNG carrier with steam propulsion plant. The measurements of various operating parameters were performed and obtained data were used for energy and exergy analysis. All the measurements and calculations were performed during the ship acceleration. The analysis shows that the energy and exergy efficiencies of both analyzed low-power turbines vary between 46% and 62% what is significantly lower in comparison with the high-power steam turbines. The ambient temperature has a low impact on exergy efficiency of analyzed turbines (change in ambient temperature for 10 °C causes less than 1% change in exergy efficiency). The highest exergy efficiencies were achieved at the lowest observed ambient temperature. Also, the highest efficiencies were achieved at 71.5% of maximum developed turbo-generator power while the highest efficiencies of steam turbine for the main feed water pump drive were achieved at maximum turbine developed power. Replacing the existing steam turbine for the main feed water pump drive with an electric motor would increase the turbo-generator energy and exergy efficiencies for at least 1–3% in all analyzed

  8. Comparative exergy analyses of gasoline and hydrogen fuelled ices

    International Nuclear Information System (INIS)

    Nieminen, J.; Dincer, I.; Yang, Y.

    2009-01-01

    Comparative exergy models for naturally aspirated gasoline and hydrogen fuelled spark ignition internal combustion engines were developed according to the second laws of thermodynamics. A thorough graphical analysis of heat transfer, work, thermo mechanical, and intake charge exergy functions was made. An irreversibility function was developed as a function of entropy generation and graphed. A second law analysis yielded a proportional exergy distribution as a fraction of the intake charge exergy. It was found that the hydrogen fuelled engine had a greater proportion of the intake charge exergy converted into work exergy, indicating a second law efficiency of 50.13% as opposed to 44.34% for a gasoline fuelled engine. The greater exergy due to heat transfer or thermal availability associated with the hydrogen fuelled engine is postulated to be a part of the reason for decreased work output of a hydrogen engine. Finally, a second law analysis of both hydrogen and gasoline combustion reactions indicate a greater combustion irreversibility associated with gasoline combustion. A percentage breakdown of the combustion irreversibilities were also constructed according to information found in literature searches. (author)

  9. Understanding the Sustainability of Fuel from the Viewpoint of Exergy

    Directory of Open Access Journals (Sweden)

    Yaning Zhang

    2018-01-01

    Full Text Available At the same time of providing a huge amount of energy to the world population (social sustainability and global economy (economic sustainability, the fuel itself also releases a great amount of emissions to the environment the world people live in in the forms of gaseous pollutants (SOx, NOx, CO, CO2, CH4, etc. and ash compositions (Al2O3, CaO, Fe2O3, K2O, MgO, MnO, Na2O, P2O5, SO3, SiO2, TiO2, etc., seriously impacting the environment (environmental sustainability for the world population and global economy. Sustainability generally encompasses economic sustainability, environmental sustainability, and social sustainability, and all of these are significantly related to the energy/resource sustainability. This study addresses the sustainability of fuel from the viewpoint of exergy. It is demonstrated that the energy of a fuel is best evaluated by its chemical exergy, and the environmental impact of a fuel can be assessed through the chemical exergy of its emissions (the specific impacts such as toxicity or greenhouse effect are not detailed. Then, the sustainability of fuel can be understood from the viewpoint of exergy through three ways: (a high chemical exergy of the fuel, (b high exergy efficiency of the fuel conversion process, and (c low chemical exergy of the emissions.

  10. Rethinking exergy efficiency in favor of exergy sustainability as a criteria for design. Paper no. IGEC-1-ID12

    International Nuclear Information System (INIS)

    Seager, T.P.

    2005-01-01

    'Full text:' Engineering design in power generation or conversion has typically focused on minimizing exergy losses (entropy gains), or maximizing economic returns. Both entropy minimization and profit maximization are readily obtainable and acceptable objective criteria for design of thermodynamic processes. However, alternative criteria are imaginable. This research presents a framework for considering minimal environmental impact or maximum renewability as alternative design criteria. In the environmental case, fuel source is based upon an exergetic environmental metric called pollution potential. In the case of renewability, a life-cycle metric describing the replacement time frame of the fuel source is employed. When coupled, the two metrics together partially assess the overall sustainability of the design. (author)

  11. Exergy costs analysis of groundwater use and water transfers

    International Nuclear Information System (INIS)

    Carrasquer, Beatriz; Uche, Javier; Martínez-Gracia, Amaya

    2016-01-01

    Highlights: • A methodology to estimate the unit exergy cost of water supply alternatives is provided. • Two alternatives (water transfers and groundwaters) are defined. • The unit exergy costs are given as a function of design and operating parameters. • Unit exergy cost of groundwaters go from 1.01 to 2.67 and from 1 to 4.06 in water transfers. • Unit exergy costs are calculated and contrasted for the medium course of the Ebro. - Abstract: In the search for new alternatives to meet the water demands, it is interesting to analyze the cost of using alternatives different from those such as desalination and pumping. The exergy cost analysis can be a useful tool to estimate costs of those alternatives as a function of its energy efficiency and its relative abundance with respect to existing resources in their surroundings. This study proposes a methodology for assessing the costs of groundwaters and water transfers from surplus basins within the exergy perspective. An equation to assess the exergy costs of these alternatives is proposed. System boundaries are first identified to the assessment of input and output currents to the system in exergy values for the design and certain operating conditions. Next, an equation to assess water supply costs depending on design and operational parameters is proposed, from the analysis of different examples. Pumping efficiency, altitude gap and flow among other features are introduced in the calculations as those characteristics parameters. In the developed examples, unit exergy costs of groundwaters go from 1.01 to 2.67, and from 1 to 4.06 in case of water transfers. Maximum values, as expected within this perspective, are found at high pumped/transferred flows and high pumping levels and/or low pumping efficiency if pumping is required.

  12. Thermodynamic exergy analysis for small modular reactor in nuclear hybrid energy system

    Directory of Open Access Journals (Sweden)

    Boldon Lauren

    2016-01-01

    Full Text Available Small modular reactors (SMRs provide a unique opportunity for future nuclear development with reduced financial risks, allowing the United States to meet growing energy demands through safe, reliable, clean air electricity generation while reducing greenhouse gas emissions and the reliance on unstable fossil fuel prices. A nuclear power plant is comprised of several complex subsystems which utilize materials from other subsystems and their surroundings. The economic utility of resources, or thermoeconomics, is extremely difficult to analyze, particularly when trying to optimize resources and costs among individual subsystems and determine prices for products. Economics and thermodynamics cannot provide this information individually. Thermoeconomics, however, provides a method of coupling the quality of energy available based on exergy and the value of this available energy – “exergetic costs”. For an SMR exergy analysis, both the physical and economic environments must be considered. The physical environment incorporates the energy, raw materials, and reference environment, where the reference environment refers to natural resources available without limit and without cost, such as air input to a boiler. The economic environment includes market influences and prices in addition to installation, operation, and maintenance costs required for production to occur. The exergetic cost or the required exergy for production may be determined by analyzing the physical environment alone. However, to optimize the system economics, this environment must be coupled with the economic environment. A balance exists between enhancing systems to improve efficiency and optimizing costs. Prior research into SMR thermodynamics has not detailed methods on improving exergetic costs for an SMR coupled with storage technologies and renewable energy such as wind or solar in a hybrid energy system. This process requires balancing technological efficiencies and

  13. Exergy analysis of a crude oil atmospheric distillation unit

    International Nuclear Information System (INIS)

    Rivero, R.; Gonzalez, G.V.; Garcia, V.H.; Pulido, R.; Escarcega, C.A.

    1989-01-01

    This paper deals with the application of an exergy analysis to an existing and operating crude oil atmospheric distillation unit. The objective of such an analysis is to fully understand where energy inefficiencies and real energy losses are located and where modifications should be implemented to improve the overall utilization of energy in the plant. First, the description of the process and the block diagram are presented. After that, the calculating procedure to obtain the exergy balance, the exergy losses, the effectiveness and the improvement potential for each plant component is described and the corresponding results are shown. Finally, the component and overall evaluations are discussed

  14. Exergy evaluation of a typical 330 MW solar-hybrid coal-fired power plant in China

    International Nuclear Information System (INIS)

    Peng, Shuo; Wang, Zhaoguo; Hong, Hui; Xu, Da; Jin, Hongguang

    2014-01-01

    Highlights: • Exergy analysis of solar-hybrid coal-fired power plant has been processed. • EUD method is utilized to obtain detailed information on the exergy destruction in each process. • Off-design thermodynamic performances are discussed to identify the advantages. • Exergy destruction of several parts under varying solar radiation is examined. - Abstract: This study discusses the thermodynamic performance of a solar-hybrid coal-fired power plant that uses solar heat with temperature lower than 300 °C to replace the extracted steam from a steam turbine to heat the feed water. Through this process, the steam that was to be extracted can efficiently expand in the steam turbine to generate electricity. The flow rate of steam returning to the turbine retains only a small part of the main stream, allowing the steam turbine to run close to design conditions for all DNI. A solar-only thermal power plant without storage is also discussed to illustrate the advantages of a solar-hybrid coal-fired power plant. The off-design performances of both plants are compared based on the energy-utilization diagram method. The exergy destruction of the solar-hybrid coal-fired power plant is found to be lower than that of the solar-only thermal power plant. The comparison of two plants, which may provide detailed information on internal phenomena, highlights several advantages of the solar-hybrid coal-fired power plant in terms of off-design operation: lower exergy destruction in the solar feed water heater and steam turbine and higher exergy and solar-to-electricity efficiency. Preliminary technological economic performances of both plants are compared. The results obtained in this study indicate that a solar-hybrid coal-fired power plant could achieve better off-design performance and economic performance than a solar-only thermal power plant

  15. Energy Analysis and Multi-Objective Optimization of an Internal Combustion Engine-Based CHP System for Heat Recovery

    Directory of Open Access Journals (Sweden)

    Abdolsaeid Ganjehkaviri

    2014-10-01

    Full Text Available A comprehensive thermodynamic study is conducted of a diesel based Combined Heat and Power (CHP system, based on a diesel engine and an Organic Rankine Cycle (ORC. Present research covers both energy and exergy analyses along with a multi-objective optimization. In order to determine the irreversibilities in each component of the CHP system and assess the system performance, a complete parametric study is performed to investigate the effects of major design parameters and operating conditions on the system’s performance. The main contribution of the current research study is to conduct both exergy and multi-objective optimization of a system using different working fluid for low-grade heat recovery. In order to conduct the evolutionary based optimization, two objective functions are considered in the optimization; namely the system exergy efficiency, and the total cost rate of the system, which is a combination of the cost associated with environmental impact and the purchase cost of each component. Therefore, in the optimization approach, the overall cycle exergy efficiency is maximized satisfying several constraints while the total cost rate of the system is minimized. To provide a better understanding of the system under study, the Pareto frontier is shown for multi-objective optimization and also an equation is derived to fit the optimized point. In addition, a closed form relationship between exergy efficiency and total cost rate is derived.

  16. Exergy analysis of a centralized air conditioning system for ice water

    International Nuclear Information System (INIS)

    Armas, Juan C; Lapido, Margarita J; Castellanos, Juan A

    2006-01-01

    An exergetic analysis of a centralized system of air conditioning, based on a vapor compression refrigeration cycle, appears in this article. The investigation allows to calculate the irreversibilities (exergy destruction) in the main components of the refrigeration cycle as well as to evaluate the sensitivity of this indicator when the operating conditions changes. As main result the most sensible components of the cycle are identified, information that will be useful in order to define strategies of operation focused to the power efficiency increase.

  17. Introduction to supercritical fluids a spreadsheet-based approach

    CERN Document Server

    Smith, Richard; Peters, Cor

    2013-01-01

    This text provides an introduction to supercritical fluids with easy-to-use Excel spreadsheets suitable for both specialized-discipline (chemistry or chemical engineering student) and mixed-discipline (engineering/economic student) classes. Each chapter contains worked examples, tip boxes and end-of-the-chapter problems and projects. Part I covers web-based chemical information resources, applications and simplified theory presented in a way that allows students of all disciplines to delve into the properties of supercritical fluids and to design energy, extraction and materials formation systems for real-world processes that use supercritical water or supercritical carbon dioxide. Part II takes a practical approach and addresses the thermodynamic framework, equations of state, fluid phase equilibria, heat and mass transfer, chemical equilibria and reaction kinetics of supercritical fluids. Spreadsheets are arranged as Visual Basic for Applications (VBA) functions and macros that are completely (source code) ...

  18. High-water-base hydraulic fluid-irradiation experiments

    International Nuclear Information System (INIS)

    Bradley, E.C.; Meacham, S.A.

    1981-10-01

    A remote system for shearing spent nuclear fuel assemblies is being designed under the direction of the Consolidated Fuel Reprocessing Program (CFRP). The design incorporates a dual hydraulic fluid actuation system in which only one of the fluids, a high-water-base (HWBF), would be exposed to ionizing radiation and radioactive contamination. A commercially available synthetic, solution-type HWBF was selected as the reference. Single-sample irradiation experiments were conducted with three commercial fluids over a range of irradiation exposures. The physical and chemical properties of the irradiated HWBFs were analyzed and compared with unirradiated samples. In general, the results of the analyses showed increasing degradation of fluid properties with increasing irradiation dose. The results also indicated that a synthetic solution-type HWBF would perform satisfactorily in the remote shear system where irradiation doses up to 10 6 Gy (10 8 rad) are expected

  19. Fines Classification Based on Sensitivity to Pore-Fluid Chemistry

    KAUST Repository

    Jang, Junbong

    2015-12-28

    The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing characteristic of fine grains, pore-fluid chemistry is not addressed in current classification systems. Liquid limits obtained with electrically contrasting pore fluids (deionized water, 2-M NaCl brine, and kerosene) are combined to define the soil "electrical sensitivity." Liquid limit and electrical sensitivity can be effectively used to classify fine grains according to their fluid-soil response into no-, low-, intermediate-, or high-plasticity fine grains of low, intermediate, or high electrical sensitivity. The proposed methodology benefits from the accumulated experience with liquid limit in the field and addresses the needs of a broader range of geotechnical engineering problems. © ASCE.

  20. Fines classification based on sensitivity to pore-fluid chemistry

    Science.gov (United States)

    Jang, Junbong; Santamarina, J. Carlos

    2016-01-01

    The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing characteristic of fine grains, pore-fluid chemistry is not addressed in current classification systems. Liquid limits obtained with electrically contrasting pore fluids (deionized water, 2-M NaCl brine, and kerosene) are combined to define the soil “electrical sensitivity.” Liquid limit and electrical sensitivity can be effectively used to classify fine grains according to their fluid-soil response into no-, low-, intermediate-, or high-plasticity fine grains of low, intermediate, or high electrical sensitivity. The proposed methodology benefits from the accumulated experience with liquid limit in the field and addresses the needs of a broader range of geotechnical engineering problems.

  1. High-water-base hydraulic fluid-irradiation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, E.C.; Meacham, S.A.

    1981-10-01

    A remote system for shearing spent nuclear fuel assemblies is being designed under the direction of the Consolidated Fuel Reprocessing Program (CFRP). The design incorporates a dual hydraulic fluid actuation system in which only one of the fluids, a high-water-base (HWBF), would be exposed to ionizing radiation and radioactive contamination. A commercially available synthetic, solution-type HWBF was selected as the reference. Single-sample irradiation experiments were conducted with three commercial fluids over a range of irradiation exposures. The physical and chemical properties of the irradiated HWBFs were analyzed and compared with unirradiated samples. In general, the results of the analyses showed increasing degradation of fluid properties with increasing irradiation dose. The results also indicated that a synthetic solution-type HWBF would perform satisfactorily in the remote shear system where irradiation doses up to 10/sup 6/ Gy (10/sup 8/ rad) are expected.

  2. Analysis of an electricity–cooling cogeneration system based on RC–ARS combined cycle aboard ship

    International Nuclear Information System (INIS)

    Liang, Youcai; Shu, Gequn; Tian, Hua; Liang, Xingyu; Wei, Haiqiao; Liu, Lina

    2013-01-01

    Highlights: • A novel electricity–cooling cogeneration system was used to recover waste heat aboard ships. • Performance of such RC–ARS system was investigated theoretically. • Optimal exergy output can be obtained when the vaporization pressure of RC is 300 kPa. • The exergy efficiency of cogeneration system is 5–12% higher than that of basic Rankine cycle only. - Abstract: In this paper, an electricity–cooling cogeneration system based on Rankine–absorption refrigeration combined cycle is proposed to recover the waste heat of the engine coolant and exhaust gas to generate electricity and cooling onboard ships. Water is selected as the working fluid of the Rankine cycle (RC), and a binary solution of ammonia–water is used as the working fluid of the absorption refrigeration cycle. The working fluid of RC is preheated by the engine coolant and then evaporated and superheated by the exhaust gas. The absorption cycle is powered by the heat of steam at the turbine outlet. Electricity output, cooling capacity, total exergy output, primary energy ratio (PER) and exergy efficiency are chosen as the objective functions. Results show that the amount of additional cooling output is up to 18 MW. Exergy output reaches the maximum 4.65 MW at the vaporization pressure of 300 kPa. The study reveals that the electricity–cooling cogeneration system has improved the exergy efficiency significantly: 5–12% increase compared with the basic Rankine cycle only. Primary energy ratio (PER) decreases as the vaporization pressure increases, varying from 0.47 to 0.40

  3. Comparative study of two weir type cascade solar stills with and without PCM storage using energy and exergy analysis

    International Nuclear Information System (INIS)

    Sarhaddi, Faramarz; Farshchi Tabrizi, Farshad; Aghaei Zoori, Halimeh; Mousavi, Seyed Amir Hossein Seyed

    2017-01-01

    Highlights: • Performance evaluation of cascade solar stills with PCM storage is carried out. • Model of cascade solar still is weir type. • Present study is based on numerical simulation. • Effect of operating parameters is studies on yield, energy and exergy efficiencies. - Abstract: In this paper, the comparative study of energy and exergy performance of two weir type cascade solar stills with and without PCM storage in sunny and semi-cloudy days is carried out. The governing equations of energy analysis include a set of nonlinear equations which is obtained by writing energy balance for the various components of a solar still (i.e. glass cover, brackish water, absorber plate, phase change materials). A detailed exergy analysis is carried out and various irreversibility rates in the solar still system and its exergy efficiency are introduced. In order to solve the governing equations a computer simulation program is developed. The results of a numerical simulation of the present study are in good agreement with the experimental data of previous literatures. The numerical results of the present study show that the energy and exergy performance of solar still without PCM storage is better than the solar still with PCM storage in sunny days. On the other hand, the solar still with PCM storage is preferred for semi-cloudy days due to its better energy and exergy performance. The maximum value of the energy and exergy efficiencies of the solar still without PCM for a typical sunny day are 76.69% and 6.53%, respectively. While, the maximum energy and exergy efficiencies of the solar still with PCM for a sample semi-cloudy day are 74.35% and 8.59%, respectively. Furthermore, it is observed that the highest irreversibility rate belongs to the absorber plate and its value for the solar still without PCM on typical sunny day and the solar still with PCM on semi-cloudy days is 83.1% and 78.8% of the whole of system irreversibility rates, respectively. Whereas, the

  4. Exergy performance of different space heating systems: A theoretical study

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

    2016-01-01

    , the effects of floor covering resistance on the whole system performance were studied using two heat sources; a natural gas fired condensing boiler and an air-source heat pump. The heating systems were also compared in terms of auxiliary exergy use for pumps and fans. The low temperature floor heating system......Three space heating systems (floor heating with different floor covering resistances, radiator heating with different working temperatures, warm-air heating with and without heat recovery) were compared using a natural gas fired condensing boiler as the heat source. For the floor heating systems...... performed better than other systems in terms of exergy demand. The use of boiler as a heat source for a low-exergy floor heating system creates a mismatch in the exergy supply and demand. Although an air-source heat pump could be a better heat source, this depends on the origin of the electricity supplied...

  5. Cogeneration with gas turbine associated to the absorption refrigeration system: a computer program for exergy economics analysis; Cogeracao com turbina a gas associada ao sistema de refrigeracao por absorcao: um programa computacional para analise exergoeconomica

    Energy Technology Data Exchange (ETDEWEB)

    Antunes, Julio Santana [UNESP, Guaratingueta, SP (Brazil). Faculdade de Engenharia. Dept. de Matematica] E-mail: santana@feg.unesp.br; Silveira, Jose Luz; Balestieri, Jose Antonio Perrella [UNESP, Guaratingueta, SP (Brazil). Faculdade de Engenharia. Dept. de Energia

    2000-07-01

    This paper presents the development of a computer program for exergy and economic analysis of cogeneration systems applying gas turbine associated to the absorption refrigeration system. The computer program selects gas turbine systems viewing the operation under thermal parity through a data base composed by gas turbines commercially available in the market, under the ISO (International Standard Organization). The computer program corrects the system performance parameters selected for the installation local conditions. The exergy and economic analysis are made based on the lowest exergy manufacturing cost where the best system is considered. A case study of the computer program application is presented.

  6. Energy and exergy analysis of the silicon production process

    International Nuclear Information System (INIS)

    Takla, M.; Kamfjord, N.E.; Tveit, Halvard; Kjelstrup, S.

    2013-01-01

    We used energy and exergy analysis to evaluate two industrial and one ideal (theoretical) production process for silicon. The industrial processes were considered in the absence and presence of power production from waste heat in the off-gas. The theoretical process, with pure reactants and no side-reactions, was used to provide a more realistic upper limit of performance for the others. The energy analysis documented the large thermal energy source in the off-gas system, while the exergy analysis documented the potential for efficiency improvement. We found an exergetic efficiency equal to 0.33 ± 0.02 for the process without power production. The value increased to 0.41 ± 0.03 when waste heat was utilized. For the ideal process, we found an exergetic efficiency of 0.51. Utilization of thermal exergy in an off-gas of 800 °C increased this exergetic efficiency to 0.71. Exergy destructed due to combustion of by-product gases and exergy lost with the furnace off-gas were the largest contributors to the thermodynamic inefficiency of all processes. - Highlights: • The exergetic efficiency for an industrial silicon production process when silicon is the only product was estimated to 0.33. • With additional power production from thermal energy in the off-gas we estimated the exergetic efficiency to 0.41. • The theoretical silicon production process is established as the reference case. • Exergy lost with the off-gas and exergy destructed due to combustion account for roughly 75% of the total losses. • With utilization of the thermal exergy in the off-gas at a temperature of 800 °C the exergetic efficiency was 0.71

  7. Exergy Analysis of a Solar Humidification- Dehumidification Desalination Unit

    OpenAIRE

    Mohammed A. Elhaj; Jamal S. Yassin

    2013-01-01

    This paper presents the exergy analysis of a desalination unit using humidification-dehumidification process. Here, this unit is considered as a thermal system with three main components, which are the heating unit by using a solar collector, the evaporator or the humidifier, and the condenser or the dehumidifier. In these components the exergy is a measure of the quality or grade of energy and it can be destroyed in them. According to the second law of thermodynamics thi...

  8. Exergy Analysis of a Subcritical Refrigeration Cycle with an Improved Impulse Turbo Expander

    Directory of Open Access Journals (Sweden)

    Zhenying Zhang

    2014-08-01

    Full Text Available The impulse turbo expander (ITE is employed to replace the throttling valve in the vapor compression refrigeration cycle to improve the system performance. An improved ITE and the corresponding cycle are presented. In the new cycle, the ITE not only acts as an expansion device with work extraction, but also serves as an economizer with vapor injection. An increase of 20% in the isentropic efficiency can be attained for the improved ITE compared with the conventional ITE owing to the reduction of the friction losses of the rotor. The performance of the novel cycle is investigated based on energy and exergy analysis. A correlation of the optimum intermediate pressure in terms of ITE efficiency is developed. The improved ITE cycle increases the exergy efficiency by 1.4%–6.1% over the conventional ITE cycle, 4.6%–8.3% over the economizer cycle and 7.2%–21.6% over the base cycle. Furthermore, the improved ITE cycle is also preferred due to its lower exergy loss.

  9. Exergy method of analysis and its application to a helium cryorefrigerator

    International Nuclear Information System (INIS)

    Thirumaleshwar, M.

    1979-01-01

    Concepts of Exergy, Exergy balance, Exergy function and Exergetic efficiency are reviewed. Curves for the Exergetic efficiency of an ideal isobaric source system for the generalised case of an ideal gas, as well as for the specific case of Helium, are presented. An Enthalpy-Exergy diagram for Helium with a pressure range of 1 atm to 150 atm and temperature range of 10 K to 300 K is drawn. Use of this chart is illustrated by analysing a modified Brayton Cycle Cryorefrigerator system with reference to each of its components. Finally, the exergy balance indicates the fraction of the total exergy supplied which is 'lost' in each of the components. (author)

  10. Energy and exergy utilizations of the Jordanian SMEs industries

    International Nuclear Information System (INIS)

    Al-Ghandoor, A.; Al Salaymeh, M.; Al-Abdallat, Y.; Al-Rawashdeh, M.

    2013-01-01

    Highlights: ► We analyze the energy and exergy utilizations of the Jordanian SMEs industries. ► We developed an energy balance for the Jordanian SMEs industries. ► The low efficiencies values suggest that many opportunities for better industrial energy utilizations still exist. - Abstract: This study presents detailed analysis of the energy and exergy utilizations of the Jordanian Small-Medium Enterprises (SMEs) by considering the flows of energy and exergy through the main end uses in the Jordanian industrial sector. To achieve this purpose, a survey covering 180 facilities was conducted and energy consumption data was gathered to establish detailed end-use balance for the Jordanian industrial sector. The energy end-use balance provides a starting point to estimate the site and embodied energy and exergy efficiencies. The average site energy and exergy efficiencies of the Jordanian SMEs industries sector are estimated as 78.3% and 37.9% respectively, while the embodied energy and exergy efficiencies are estimated as 58.9% and 21.2% respectively. The low efficiencies values suggest that many opportunities for better industrial energy utilizations still exist.

  11. New exergy analysis of a regenerative closed Brayton cycle

    International Nuclear Information System (INIS)

    Naserian, Mohammad Mahdi; Farahat, Said; Sarhaddi, Faramarz

    2017-01-01

    Highlights: • The maximum power is studied relating to time and size constraints variations. • The influence of time and size constraints on exergy destruction are investigated. • The definitions of heat exergy, and second law efficiency are modified. - Abstract: In this study, the optimal performance of a regenerative closed Brayton cycle is sought through power maximization. Optimization is performed on the output power as the objective function using genetic algorithm. In order to take into account the time and the size constraints in current problem, the dimensionless mass-flow parameter is used. The influence of the unavoidable exergy destruction due to finite-time constraint is taken into account by developing the definition of heat exergy. Finally, the improved definitions are proposed for heat exergy, and the second law efficiency. Moreover, the new definitions will be compared with the conventional ones. For example, at a specified dimensionless mass-flow parameter, exergy overestimation in conventional definition, causes about 31% lower estimation of the second law efficiency. These results could be expected to be utilized in future solar thermal Brayton cycle assessment and optimization.

  12. Hydrogen Economy Model for Nearly Net-Zero Cities with Exergy Rationale and Energy-Water Nexus

    Directory of Open Access Journals (Sweden)

    Birol Kılkış

    2018-05-01

    Full Text Available The energy base of urban settlements requires greater integration of renewable energy sources. This study presents a “hydrogen city” model with two cycles at the district and building levels. The main cycle comprises of hydrogen gas production, hydrogen storage, and a hydrogen distribution network. The electrolysis of water is based on surplus power from wind turbines and third-generation solar photovoltaic thermal panels. Hydrogen is then used in central fuel cells to meet the power demand of urban infrastructure. Hydrogen-enriched biogas that is generated from city wastes supplements this approach. The second cycle is the hydrogen flow in each low-exergy building that is connected to the hydrogen distribution network to supply domestic fuel cells. Make-up water for fuel cells includes treated wastewater to complete an energy-water nexus. The analyses are supported by exergy-based evaluation metrics. The Rational Exergy Management Efficiency of the hydrogen city model can reach 0.80, which is above the value of conventional district energy systems, and represents related advantages for CO2 emission reductions. The option of incorporating low-enthalpy geothermal energy resources at about 80 °C to support the model is evaluated. The hydrogen city model is applied to a new settlement area with an expected 200,000 inhabitants to find that the proposed model can enable a nearly net-zero exergy district status. The results have implications for settlements using hydrogen energy towards meeting net-zero targets.

  13. Gas inflow in oil base fluids; Influxo de gas em fluidos a base de oleo

    Energy Technology Data Exchange (ETDEWEB)

    Lazaro, Welmar [PETROBRAS, Rio de Janeiro (Brazil). Dept. de Perfuracao. Div. de Fluidos de Perfuracao; Boas, Mario Barbosa V [PETROBRAS, Rio de Janeiro (Brazil). Centro de Pesquisas. Div. de Explotacao

    1990-12-31

    One of the major problems related to the use of oil base fluids is the dissolution of the natural gas in the fluid. This paper attempts initially at making a bibliographical review of all that was written on the subject of drilling fluids up to now. It also mentions some theoretical aspects regarding the process of gas dissolution in diesel oils, in order to produce an understanding of how the dissolution mechanism is processed. For a same increase in measured volume on the surface, the amount of gas incorporated into the fluid is significantly larger if the gas is dissolved in the oil phase than if it is emulsified in the fluid, as occurs when the fluid is water base. A rig team used to working with water-base fluids may be surprised with the fact that an increase of 20 bbl of fluid on the surface of a 5000 m well can mean the incorporation of about 1800 m{sup 3} of gas, if the fluid is oil-base and all the gas is in solution instead of the incorporation of 900 m{sup 3} if the fluid is water base. This paper has the goal of warning drilling engineers and technicians about this problem, as well as presenting charts and equations that allow for a more realistic evaluation of the amount of gas incorporated into oil fluids. (author) 16 refs., 7 figs., 2 tabs.

  14. Analysis of temperature glide matching of heat pumps with zeotropic working fluid mixtures for different temperature glides

    DEFF Research Database (Denmark)

    Zühlsdorf, Benjamin; Jensen, Jonas Kjær; Cignitti, Stefano

    2018-01-01

    refrigerants. This approach enables a match of the temperature glide of sink and source with the temperature of the working fluid during phase change and thus, a reduction of the exergy destruction due to heat transfer. The model was evaluated for four different boundary conditions. The exergy destruction due...

  15. Exergy analysis and optimisation of a marine molten carbonate fuel cell system in simple and combined cycle configuration

    International Nuclear Information System (INIS)

    Dimopoulos, George G.; Stefanatos, Iason C.; Kakalis, Nikolaos M.P.

    2016-01-01

    Highlights: • Process modelling and optimisation of an integrated marine MCFC system. • Component-level and spatially distributed exergy analysis and balances. • Optimal simple cycle MCFC system with 45.5% overall exergy efficiency. • Optimal combined cycle MCFC system with 60% overall exergy efficiency. • Combined cycle MCFC system yields 30% CO_2 relative emissions reduction. - Abstract: In this paper we present the exergy analysis and design optimisation of an integrated molten carbonate fuel cell (MCFC) system for marine applications, considering waste heat recovery options for additional power production. High temperature fuel cells are attractive solutions for marine energy systems, as they can significantly reduce gaseous emissions, increase efficiency and facilitate the introduction of more environmentally-friendly fuels, like LNG and biofuels. We consider an already installed MCFC system onboard a sea-going vessel, which has many tightly integrated sub-systems and components: fuel delivery and pre-reforming, internal reforming sections, electrochemical conversion, catalytic burner, air supply and high temperature exhaust gas. The high temperature exhaust gasses offer significant potential for heat recovery that can be directed into both covering the system’s auxiliary heat requirements and power production. Therefore, an integrated systems approach is employed to accurately identify the true sources of losses in the various components and to optimise the overall system with respect to its energy efficiency, taking into account the various trade-offs and subject to several constraints. Here, we present a four-step approach: a. dynamic process models development of simple and combined-cycle MCFC system; b. MCFC components and system models calibration via onboard MCFC measurements; c. exergy analysis, and d. optimisation of the simple and combined-cycle systems with respect to their exergetic performance. Our methodology is based on the

  16. Exergetic evaluation on photovoltaic/thermal hybrid panel; Taiyoko netsu hybrid panel no exergy hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Iwaki, H; Morita, Y; Fujisawa, T; Tani, T [Science University of Tokyo, Tokyo (Japan)

    1996-10-27

    The photovoltaic/thermal hybrid panel (PV/T) is an energy converter that was designed for the composite use of electricity and heat. In this paper, the validity of PV/T designed for trial was evaluated based on an exergetic theory. As the result of an experiment, the electric exergetic value of PV/T and PV is each 65.8 kWh/m{sup 2} and 58.6 kWh/m{sup 2}. The former is higher than the latter by 11.2%. The total exergetic value of PV/T is also 1.2 and 8.2 times as high as those of a PV and solar collector (SC), respectively. The calculation result of the optimum temperature operation showed that the exergetic value of PV/T is 3.1 times as high as the electric exergetic value. Therefore, the operation must be performed with the electric and thermal exergetic values set in a ratio of 3.1 to 1. In this paper, the operating mode is handled in which importance was more attached to the electric exergy than the thermal exergy. The flow rate of a heating medium on PV/T is not thus the flow control that maximizes the PV/T exergy. In the future, studies including these points will be promoted. 7 refs., 7 figs., 3 tabs.

  17. Inferring community properties of benthic macroinvertebrates in streams using Shannon index and exergy

    Science.gov (United States)

    Nguyen, Tuyen Van; Cho, Woon-Seok; Kim, Hungsoo; Jung, Il Hyo; Kim, YongKuk; Chon, Tae-Soo

    2014-03-01

    Definition of ecological integrity based on community analysis has long been a critical issue in risk assessment for sustainable ecosystem management. In this work, two indices (i.e., Shannon index and exergy) were selected for the analysis of community properties of benthic macroinvertebrate community in streams in Korea. For this purpose, the means and variances of both indices were analyzed. The results found an extra scope of structural and functional properties in communities in response to environmental variabilities and anthropogenic disturbances. The combination of these two parameters (four indices) was feasible in identification of disturbance agents (e.g., industrial pollution or organic pollution) and specifying states of communities. The four-aforementioned parameters (means and variances of Shannon index and exergy) were further used as input data in a self-organizing map for the characterization of water quality. Our results suggested that Shannon index and exergy in combination could be utilized as a suitable reference system and would be an efficient tool for assessment of the health of aquatic ecosystems exposed to environmental disturbances.

  18. Exergy analysis on the irreversibility of rotary air preheater in thermal power plant

    International Nuclear Information System (INIS)

    Wang Hongyue; Zhao Lingling; Zhou Qiangtai; Xu Zhigao; Kim, Hyung Taek

    2008-01-01

    Energy recovery devices can have a substantial impact on process efficiency and their relevance to the problem of conservation of energy resources is generally recognized to be beyond dispute. One type of such a device, which is commonly used in thermal power plants and air conditioning systems, is the rotary air preheater. A major disadvantage of the rotary air preheater is that there is an unavoidable leakage due to carry over and pressure difference. There are gas streams involved in the heat transfer and mixing processes. There are also irreversibilities, or exergy destruction, due to mixing, pressure losses and temperature gradients. Therefore, the purpose of this research paper is based from the second law of thermodynamics, which is to build up the relationship between the efficiency of the thermal power plant and the total process of irreversibility in the rotary air preheater using exergy analysis. For this, the effects of the variation of the principal design parameters on the rotary air preheater efficiency, the exergy efficiency, and the efficiency of the thermal power plant are examined by changing a number of parameters of rotary air preheater. Furthermore, some conclusions are reached and recommendations are made so as to give insight on designing some optimal parameters

  19. Comparative effects of building envelope improvements and occupant behavioural changes on the exergy consumption for heating and cooling

    International Nuclear Information System (INIS)

    Schweiker, Marcel; Shukuya, Masanori

    2010-01-01

    Much focus is put on measures to improve the building envelope system performance to reduce the impact of the building sector on the global environmental degradation. This paper compares the potential of building envelope improvements to those of a change in the occupant's behavioural pattern. Three cases of improvements together with a base case were analysed using exergy analysis, because the exergy concept is useful to understand the underlying processes and the necessary adjustments to the calculation of the heat-pump system. The assumptions for the occupant behaviour were set up based on our field measurements conducted in a dormitory building and the calculation was for steady-state conditions. It was found that the potential of occupant behavioural changes for the reduction in exergy consumption is more affected by the outdoor temperature compared to building envelope improvements. The influence of occupant behaviour was highly significant (more than 90% decrease of exergy consumption) when the temperature difference between indoors and outdoors is small, which is the case for long periods in regions with moderate temperatures during summer and/or winter. Nevertheless, both measures combined lead to a reduction from 76% up to 95% depending on the outside conditions and should be the final goal.

  20. Polyalkylene glycols, base fluids for special lubricants and hydraulic fluids; Polyalkylenglykole, Basisoele fuer Spezialschmierstoffe und Hydraulikfluessigkeiten

    Energy Technology Data Exchange (ETDEWEB)

    Poellmann, K. [Clariant GmbH (Germany)

    2004-08-01

    For many years polyalkylene glycols have been used as base fluids for special lubricants. In this matter they compete with polyol esters and polyalphaolefines. Synthesis of polyalkylen glycols is founded upon the anionic polymerisation of ethyleneoxid, propyleneoxid and if necessary of other oxigen-containing monomeres. The flexibility of this synthesis is the reason that polyalkylene glycole is a collective term, including a broad group of base fluids with partly extreme different properties. Typical for polyalkylene glycols is a high viscosity-index, watersolubility and adsorbing power for water, low friction numbers, but also the incompatibility with current mineral-oil-soluble additive systems. Because of this quality profile there has been developped specific niche-applications in the lubricant-area for polyalkylene glycols in the last 30 years, where each of the specific benefits has been used. Among them are watercontaining HFC hydraulicfluids, refrigerator oils, and oils for ethylene-compressors. HFC fluids are formulated with high-viscous, water-soluble polyalkylene glycols. For refrigerator oils in motor-car conditioning the R 134A compatibility of water-insoluble polyalkylene glycols is essential. For the use in ethylene-compressors the crucial point is the insolubility of polyalkylene glycol in ethylene. (orig.)

  1. Performances of cutting fluids in turning. Vegetable based oil - RV

    DEFF Research Database (Denmark)

    Axinte, Dragos Aurelian; Belluco, Walter

    1999-01-01

    Scope of the present measurement campaign is the evaluation of the cutting fluid performance. The report presents the standard routine and the results obtained when turning stainless steel and brass with a commercial vegetable based oil called RV. The methods were developed to be applicable...

  2. A Study Of Magnetic Fluid Based Squeeze Film Between Porous ...

    African Journals Online (AJOL)

    Efforts have been made to study and analyze the effect of surface roughness on the performance of magnetic fluid based squeeze film between porous elliptic plates. The transverse roughness of the bearing surface is characterized by a stochastic random variable with non-zero mean, variance and skewness.

  3. Temperature dependence of photonic crystals based on thermoresponsive magnetic fluids

    International Nuclear Information System (INIS)

    Pu Shengli; Bai Xuekun; Wang Lunwei

    2011-01-01

    The influence mechanisms of temperature on the band gap properties of the magnetic fluids based photonic crystals are elaborated. A method has been developed to obtain the temperature-dependent structure information (A sol /A) from the existing experimental data and then two critical parameters, i.e. the structure ratio (d/a) and the refractive index contrast (Δn) of the magnetic fluids photonic crystals are deduced for band diagram calculations. The temperature-dependent band gaps are gained for z-even and z-odd modes. Band diagram calculations display that the mid frequencies and positions of the existing forbidden bands are not very sensitive to the temperature, while the number of the forbidden bands at certain strengths of magnetic field may change with the temperature variation. The results presented in this work give a guideline for designing the potential photonic devices based on the temperature characteristics of the magnetic fluids based photonic crystals and are helpful for improving their quality. - Highlights: → Mechanisms of temperature dependence of magnetic fluids based photonic crystals are elaborated. → Properties of existing forbidden bands have relatively fine temperature stability. → Disappearance of existing forbidden band is found for some magnetic fields. → Emergence of new forbidden band with temperature is found for some magnetic fields.

  4. Fines Classification Based on Sensitivity to Pore-Fluid Chemistry

    KAUST Repository

    Jang, Junbong; Santamarina, Carlos

    2015-01-01

    The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing

  5. Drilling fluid base oil biodegradation potential of a soil ...

    African Journals Online (AJOL)

    Staphylococcus sp. isolated from oil-contaminated soil was grown in 1% drilling fluid base oil, HDF- 2000, as a sole source of carbon and energy. The organism has strong affinity for the substrate, growing at the rate of 0.16 h-1. It uses adherence and emulsification as mechanisms for oil uptake. In a nutrient-rich marine ...

  6. Optimization of morphing flaps based on fluid structure interaction modeling

    DEFF Research Database (Denmark)

    Barlas, Athanasios; Akay, Busra

    2018-01-01

    This article describes the design optimization of morphing trailing edge flaps for wind turbines with ‘smart blades’. A high fidelity Fluid Structure Interaction (FSI) simulation framework is utilized, comprised of 2D Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) models....... A coupled aero-structural simulation of a 10% chordwise length morphing trailing edge flap for a 4 MW wind turbine rotor is carried out and response surfaces are produced with respect to the flap internal geometry design parameters for the design conditions. Surrogate model based optimization is applied...

  7. Accurate fluid force measurement based on control surface integration

    Science.gov (United States)

    Lentink, David

    2018-01-01

    Nonintrusive 3D fluid force measurements are still challenging to conduct accurately for freely moving animals, vehicles, and deforming objects. Two techniques, 3D particle image velocimetry (PIV) and a new technique, the aerodynamic force platform (AFP), address this. Both rely on the control volume integral for momentum; whereas PIV requires numerical integration of flow fields, the AFP performs the integration mechanically based on rigid walls that form the control surface. The accuracy of both PIV and AFP measurements based on the control surface integration is thought to hinge on determining the unsteady body force associated with the acceleration of the volume of displaced fluid. Here, I introduce a set of non-dimensional error ratios to show which fluid and body parameters make the error negligible. The unsteady body force is insignificant in all conditions where the average density of the body is much greater than the density of the fluid, e.g., in gas. Whenever a strongly deforming body experiences significant buoyancy and acceleration, the error is significant. Remarkably, this error can be entirely corrected for with an exact factor provided that the body has a sufficiently homogenous density or acceleration distribution, which is common in liquids. The correction factor for omitting the unsteady body force, {{{ {ρ f}} {1 - {ρ f} ( {{ρ b}+{ρ f}} )}.{( {{{{ρ }}b}+{ρ f}} )}}} , depends only on the fluid, {ρ f}, and body, {{ρ }}b, density. Whereas these straightforward solutions work even at the liquid-gas interface in a significant number of cases, they do not work for generalized bodies undergoing buoyancy in combination with appreciable body density inhomogeneity, volume change (PIV), or volume rate-of-change (PIV and AFP). In these less common cases, the 3D body shape needs to be measured and resolved in time and space to estimate the unsteady body force. The analysis shows that accounting for the unsteady body force is straightforward to non

  8. Effect of the use of olive–pomace oil biodiesel/diesel fuel blends in a compression ignition engine: Preliminary exergy analysis

    International Nuclear Information System (INIS)

    López, I.; Quintana, C.E.; Ruiz, J.J.; Cruz-Peragón, F.; Dorado, M.P.

    2014-01-01

    Highlights: • Olive–pomace oil (OPO) biodiesel constitute a new second-generation biofuel. • Exergy efficiency and performance of OPO biodiesel, straight and blended with diesel fuel was evaluated. • OPO biodiesel, straight and blended, provided similar performance parameters. • OPO biodiesel, straight and blended, provided similar exergy efficiency compared to diesel fuel. • OPO biodiesel, straight and blended, provided no exergy cost increment compared to diesel fuel. - Abstract: Although biodiesel is among the most studied biofuels for diesel engines, it is usually produced from edible oils, which gives way to controversy between the use of land for fuel and food. For this reason, residues like olive–pomace oil are considered alternative raw materials to produce biodiesel that do not compete with the food industry. To gain knowledge about the implications of its use, olive–pomace oil methyl ester, straight and blended with diesel fuel, was evaluated as fuel in a direct injection diesel engine Perkins AD 3-152 and compared to the use of fossil diesel fuel. Performance curves were analyzed at full load and different speed settings. To perform the exergy balance of the tested fuels, the operating conditions corresponding to maximum engine power values were considered. It was found that the tested fuels offer similar performance parameters. When straight biodiesel was used instead of diesel fuel, maximum engine power decreased to 5.6%, while fuel consumption increased up to 7%. However, taking into consideration the Second Law of the Thermodynamics, the exergy efficiency and unitary exergetic cost reached during the operation of the engine under maximum power condition for the assessed fuels do not display significant differences. Based on the exergy results, it may be concluded that olive–pomace oil biodiesel and its blends with diesel fuel may substitute the use of diesel fuel in compression ignition engines without any exergy cost increment

  9. Exergy analysis of scroll compressors working with R22, R407C, and R417A as refrigerant for HVAC system

    Directory of Open Access Journals (Sweden)

    Kalaiselvam Sivakumar

    2009-01-01

    Full Text Available The rise in crisis of power enthralls the world economically and the options for conventional and non-conventional energy resources have been searched out. No system exists in this world with 100% efficiency due to several irreversibility's. If the output obtained from the system is maximum for a given input, maximum amount of energy can be saved globally. To understand the thermodynamic losses occurring in the system and to predict the available energy that can be tapped from the system, exergy plays a major role. Experimental study on exergy in a system can pave the way to understand the complete behavior of the system exergually. Conceptually exergy studies are based on simulation, to provide a new dimension to the concept of exergy experimental validation have been promoted. The analogy of exergy analysis of three refrigerants working in scroll compressors and their exergual features are explained in this paper. The refrigerants R22, R417A, and R407C and their thermo dynamical behavior, irreversibility were experimented in an air conditioning system with three scroll compressors, interaction between the system and the refrigerant in terms of pressure drop and heat transfer, friction has been implemented for the calculation of exergy. The entire system performance on the basis of refrigerant is validated in each part of the air conditioning system. The resultant coefficient of performance of R407C is 2.41% less than R22 in a R22 designed scroll compressor with minimal exergy losses. The second law efficiency of 50 to 55% obtained in R22 has fewer rules over R407C and R417A which has 48 to 52%. The diminutive deviation of results encourages R417A refrigerant to be used as a substitute for R22. Thus the exergual prediction of performance of refrigerant and second law efficiency can identify the use of eco-friendly refrigerant in scroll compressor.

  10. Two Examples of Exergy Optimization Regarding the “Thermo-Frigopump” and Combined Heat and Power Systems

    Directory of Open Access Journals (Sweden)

    Michel Feidt

    2013-02-01

    Full Text Available In a recent review an optimal thermodynamics and associated new upper bounds have been proposed, but it was only relative to power delivered by engines. In fact, it appears that for systems and processes with more than one utility (mainly mechanical or electrical power, energy conservation (First Law is limited for representing their efficiency. Consequently, exergy analysis combining the First and Second Law seems essential for optimization of systems or processes situated in their environment. For thermomechanical systems recent papers report on comparisons between energy and exergy analysis and corresponding optimization, but the proposed models mainly use heat transfer conductance modelling, except for internal combustion engine. Here we propose to reconsider direct and inverse configurations of Carnot machines, with two examples. The first example is concerned with “thermofrigo-pump” where the two utilities are hot and cold thermal exergies due to the difference in the temperature level compared to the ambient one. The second one is relative to a “combined heat and power” (CHP system. In the two cases, the model is developed based on the Carnot approach, and use of the efficiency-NTU method to characterize the heat exchangers. Obtained results are original thermodynamics optima, that represent exergy upper bounds for these two cases. Extension of the proposed method to other systems and processes is examined, with added technical constraints or not.

  11. Experimental and numerical analysis of the optimized finned-tube heat exchanger for OM314 diesel exhaust exergy recovery

    International Nuclear Information System (INIS)

    Hatami, M.; Ganji, D.D.; Gorji-Bandpy, M.

    2015-01-01

    Highlights: • An optimized finned-tube heat exchanger is modeled. • Artificial Neural Networks and Genetic Algorithm are applied. • Exergy recovery from exhaust of a diesel engine is studied. - Abstract: In this research, a multi objective optimization based on Artificial Neural Network (ANN) and Genetic Algorithm (GA) are applied on the obtained results from numerical outcomes for a finned-tube heat exchanger (HEX) in diesel exhaust heat recovery. Thirty heat exchangers with different fin length, thickness and fin numbers are modeled and those results in three engine loads are optimized with weight functions for pressure drop, recovered heat and HEX weight. Finally, two cases of HEXs (an optimized and a non-optimized) are produced experimentally and mounted on the exhaust of an OM314 diesel engine to compare their results in heat and exergy recovery. All experiments are done for five engine loads (0%, 20%, 40%, 60% and 80% of full load) and four water mass flow rates (50, 40, 30 and 20 g/s). Results show that maximum exergy recovers occurs in high engine loads and optimized HEX with 10 fins have averagely 8% second law efficiency in exergy recovery

  12. Energy and exergy evaluation of a 220MW thermal power plant ...

    African Journals Online (AJOL)

    Energy and exergy evaluation of a 220MW thermal power plant. ... Nigerian Journal of Technology ... At the variation of environmental or dead state temperature, ther e were no appreciable changes in the values of exergy efficiency of the ...

  13. Exergy analysis of heating, refrigerating and air conditioning methods and applications

    CERN Document Server

    Dincer, Ibrahim

    2015-01-01

    Improve and optimize efficiency of HVAC and related energy systems from an exergy perspective. From fundamentals to advanced applications, Exergy Analysis of Heating, Air Conditioning, and Refrigeration provides readers with a clear and concise description of exergy analysis and its many uses. Focusing on the application of exergy methods to the primary technologies for heating, refrigerating, and air conditioning, Ibrahim Dincer and Marc A. Rosen demonstrate exactly how exergy can help improve and optimize efficiency, environmental performance, and cost-effectiveness. The book also discusses the analysis tools available, and includes many comprehensive case studies on current and emerging systems and technologies for real-world examples. From introducing exergy and thermodynamic fundamentals to presenting the use of exergy methods for heating, refrigeration, and air conditioning systems, this book equips any researcher or practicing engineer with the tools needed to learn and master the application of exergy...

  14. Advanced exergy analysis for a bottoming organic rankine cycle coupled to an internal combustion engine

    International Nuclear Information System (INIS)

    Galindo, J.; Ruiz, S.; Dolz, V.; Royo-Pascual, L.

    2016-01-01

    Highlights: • Advanced exergy analysis were carried out using experimental data of an ORC. • Exergy destruction analyzed as endogenous/exogenous and unavoidable/avoidable. • Exergy destruction was estimated by considering technological restrictions. - Abstract: This paper deals with the evaluation and analysis of a bottoming ORC cycle coupled to an IC engine by means of conventional and advanced exergy analysis. Using experimental data of an ORC coupled to a 2 l turbocharged engine, both conventional and advanced exergy analysis are carried out. Splitting the exergy in the advanced exergy analysis into unavoidable and avoidable provides a measure of the potential of improving the efficiency of this component. On the other hand, splitting the exergy into endogenous and exogenous provides information between interactions among system components. The result of this study shows that there is a high potential of improvement in this type of cycles. Although, from the conventional analysis, the exergy destruction rate of boiler is greater than the one of the expander, condenser and pump, the advanced exergy analysis suggests that the first priority of improvement should be given to the expander, followed by the pump, the condenser and the boiler. A total amount of 3.75 kW (36.5%) of exergy destruction rate could be lowered, taking account that only the avoidable part of the exergy destruction rate can be reduced.

  15. Exergy transfer and parametric study of counter flow wet cooling towers

    International Nuclear Information System (INIS)

    Wang Li; Li Nianping

    2011-01-01

    A thermodynamic analysis of the counter flow wet cooling tower (CWCT) is performed in this paper. Both energy and exergy formulations are developed and validated for the system. Four types of exergy transfer processes occurring inside the CWCT are investigated schematically. A parametric study is conducted under various operating conditions in order to investigate the effects of thermal efficiency and water-to-air ratio on the exergy performance of the CWCT. Unlike past studies, the transiting exergy contained in the inlet and outlet water is not considered. It is found that the exergy efficiency is always less than 25%. The exergy parameters including evaporation water loss, exergy efficiency, exergy input, internal and external exergy losses are very sensitive to the thermal efficiency when it is very close to 1.0 at lower water-to-air ratios. - Research highlights: → We model counter flow wet cooling towers and make a detailed exergy analysis. → Four types of exergy transfer processes are investigated schematically. → Only a small part of exergy input, less than 25%, is effectively utilized.

  16. Advanced exergy analyses of an ejector expansion transcritical CO_2 refrigeration system

    International Nuclear Information System (INIS)

    Bai, Tao; Yu, Jianlin; Yan, Gang

    2016-01-01

    Highlights: • Advanced exergy analyses are performed on CO_2 EERC cycle. • Compressor should be improved first, followed by ejector, evaporator and gas cooler. • Interactions among the system components are assessed with advanced exergy analysis. • Real potential for exergy destruction reduction of the system is 43.44%. - Abstract: This paper presents a thermodynamic investigation on an ejector expansion transcritical CO_2 refrigeration system with advanced exergy analysis. By splitting the exergy destruction into endogenous/exogenous and unavoidable/avoidable parts, more valuable information of the interactions among the system components and the components improvement potential is provided. The results indicate that the compressor with largest avoidable endogenous exergy destruction possesses the highest priority of improvement, followed by the ejector, evaporator and gas cooler. The system exergy destruction is dominantly endogenous, and 43.44% of the total exergy destruction can be avoided by improving the system components. The evaporator has a serious impact on the exogenous exergy destruction within the compressor and ejector, and its own exergy destruction is entirely belongs to endogenous part. The effects of the discharge pressure, compressor efficiency and ejector efficiency on the system exergetic performance are discussed. There is an optimal discharge pressure with respect to the minimum endogenous exergy destruction in the compressor. Avoidable endogenous exergy destruction rates of the compressor and ejector are respectively reduced by 93.6% and 81.7% when the corresponding component efficiency varies from 0.5 to 0.9.

  17. Energy and exergy analysis of industrial fluidized bed drying of paddy

    International Nuclear Information System (INIS)

    Sarker, Md. Sazzat Hossain; Ibrahim, Mohd Nordin; Abdul Aziz, Norashikin; Punan, Mohd Salleh

    2015-01-01

    This paper presents energy and exergy analysis of industrial fluidized bed paddy drying. The maximum design capacity of the dryer was 22 t/h. Existing energy and exergy models developed applying the First and Second law of Thermodynamics are employed to estimate the amounts of energy used, the ratios of energy utilization, magnitude of exergy losses and exergy efficiencies during the drying process. The analysis shows that energy usage and (EUR) energy utilization ratios vary between 38.91 kJ/s to 132.00 kJ/s and 5.24–13.92 %, respectively while exergy efficiency vary from 46.99 to 58.14%. A simple exergy balance reveals that only 31.18–37.01 % exergy are utilized for drying of paddy and the remaining large amount of exergy are wasted. Exergy can be increased through providing sufficient insulation on dryer body and recycling the exhaust air which need to be studied further for investigating the economic feasibility. - Highlights: • Energy and exergy analysis of industrial fluidized bed paddy drying are presented. • Energy usage varies from 38.91 kJ/s to 132.00 kJ/s. • Energy usage ratio is found to vary between 5.24 and 13.38%. • Exergy efficiency varies from 41.30 to 58.14%. • Only 31.18–37.01 % exergy are utilized in the paddy drying system

  18. The application of exergy to human-designed systems

    Science.gov (United States)

    Hamilton, P.

    2012-12-01

    Exergy is the portion of the total energy of a system that is available for conversion to useful work. Exergy takes into account both the quantity and quality of energy. Heat is the inevitable product of using any form of high-quality energy such as electricity. Modern commercial buildings and industrial facilities use large amounts of electricity and so produce huge amounts of heat. This heat energy typically is treated as a waste product and discharged to the environment and then high-quality energy sources are consumed to satisfy low-quality energy heating and cooling needs. Tens of thousands of buildings and even whole communities could meet much of their heating and cooling needs through the capture and reuse of heat energy. Yet the application of exergy principles often faces resistance because it challenges conventions about how we design, construct and operate human-engineered systems. This session will review several exergy case studies and conclude with an audience discussion of how exergy principles may be both applied and highlighted in formal and informal education settings.

  19. A novel syngas-fired hybrid heating source for solar-thermal applications: Energy and exergy analysis

    International Nuclear Information System (INIS)

    Pramanik, Santanu; Ravikrishna, R.V.

    2016-01-01

    Highlights: • Biomass-derived syngas as a hybrid energy source for solar thermal power plants. • A novel combustor concept using rich-catalytic and MILD combustion technologies. • Hybrid energy source for a solar-driven supercritical CO 2 -based Brayton cycle. • Comprehensive energetic and exergetic analysis of the combined system. - Abstract: A hybrid heating source using biomass-derived syngas is proposed to enable continuous operation of standalone solar thermal power generation plants. A novel, two-stage, low temperature combustion system is proposed that has the potential to provide stable combustion of syngas with near-zero NO x emissions. The hybrid heating system consists of a downdraft gasifier, a two-stage combustion system, and other auxiliaries. When integrated with a solar cycle, the entire system can be referred to as the integrated gasification solar combined cycle (IGSCC). The supercritical CO 2 Brayton cycle (SCO 2 ) is selected for the solar cycle due to its high efficiency. The thermodynamic performance evaluation of the individual unit and the combined system has been conducted from both energy and exergy considerations. The effect of parameters such as gasification temperature, biomass moisture content, equivalence ratio, and pressure ratio is studied. The efficiency of the IGSCC exhibited a non-monotonic behavior. A maximum thermal efficiency of 36.5% was achieved at an overall equivalence ratio of 0.22 and pressure ratio of 2.75 when the gasifier was operating at T g = 1073 K with biomass containing 20% moisture. The efficiency increased to 40.8% when dry biomass was gasified at a temperature of 973 K. The exergy analysis revealed that the maximum exergy destruction occurred in the gasification system, followed by the combustion system, SCO 2 cycle, and regenerator. The exergy analysis also showed that 8.72% of the total exergy is lost in the exhaust; however, this can be utilized for drying of the biomass.

  20. Synthetic-based fluid replacement: excellent drilling efficiency and imaging evaluation achieved with inhibitive water-based fluid

    Energy Technology Data Exchange (ETDEWEB)

    Mendonca, Ricardo; Fernandez, Jovan Andrade [PETROBRAS, Rio de Janeiro, RJ (Brazil); Anderson, Tom; Loureiro, Mario; Pereira, Alex; Shah, Fayyaz [Halliburton Baroid, Aracaju, SE (Brazil)

    2004-07-01

    The highly reactive Calumbi shale is encountered in wells drilled by PETROBRAS in the Sergipe area. Normally an invert emulsion fluid would be used. However, the ability to run high resolution imaging logs was crucial to determining the potential of the offshore Sergipe fields, and these tools work best in water-based fluids. PETROBRAS selected a new high performance water-based fluid (WBF) to drill the Poco 3-GA-73-SES well. The fluid selection was based on the results of X-ray diffraction, dispersion/erosion and linear swell meter testing of Calumbi formation samples. The new WBF incorporates a unique polymer chemistry that can provide shale inhibition very similar to that achieved with an invert emulsion fluid, without sacrificing drilling performance. The polymeric additives can effectively flocculate and encapsulate colloidal drill solids so that they can be easily removed mechanically. The polymers also help prevent hole erosion and bit balling. After the high-performance WBF was used, the following results were obtained on the Poco 3- GA-73-SES well: 805 m drilled in 65 hr (12.65 m/hr) in a single bit run; trips completed with minimal use of the pumps or back reaming, considered exceptional for a WBF while drilling the Calumbi shale; imaging logs run successfully with no delays or obstructions while tripping or logging; the average hole diameter was 8.63-in. per the caliper log for the 8 1/2-in. section; no accretion on the bit or drill string observed; no flow line plugging or shaker screen blinding. (author)

  1. Exergy Analyses of Fabricated Compound Parabolic Solar Collector with Evacuated Tubes at Different Operating Conditions: Indore (India)

    Science.gov (United States)

    Geete, Ankur; Dubey, Akash; Sharma, Ankush; Dubey, Anshul

    2018-05-01

    In this research work, compound parabolic solar collector (CPC) with evacuated tubes is fabricated. Main benefit of CPC is that there is no requirement of solar tracking system. With fabricated CPC; outlet temperatures of flowing fluid, instantaneous efficiencies, useful heat gain rates and inlet exergies (with and without considering Sun's cone angle) are experimentally found. Observations are taken at different time intervals (1200, 1230, 1300, 1330 and 1400 h), mass flow rates (1.15, 0.78, 0.76, 0.86 and 0.89 g/s), ambient temperatures and with various dimensions of solar collector. This research work is concluded as; maximum instantaneous efficiency is 69.87% which was obtained with 0.76 g/s flow rate of water at 1300 h and 42°C is the maximum temperature difference which was also found at same time. Maximum inlet exergies are 139.733 and 139.532 kW with and without considering Sun's cone angle at 1300 h, respectively. Best thermal performance from the fabricated CPC with evacuated tubes is found at 1300 h. Maximum inlet exergy is 141.365 kW which was found at 1300 h with 0.31 m aperture width and 1.72 m absorber pipe length.

  2. Model identification methodology for fluid-based inerters

    Science.gov (United States)

    Liu, Xiaofu; Jiang, Jason Zheng; Titurus, Branislav; Harrison, Andrew

    2018-06-01

    Inerter is the mechanical dual of the capacitor via the force-current analogy. It has the property that the force across the terminals is proportional to their relative acceleration. Compared with flywheel-based inerters, fluid-based forms have advantages of improved durability, inherent damping and simplicity of design. In order to improve the understanding of the physical behaviour of this fluid-based device, especially caused by the hydraulic resistance and inertial effects in the external tube, this work proposes a comprehensive model identification methodology. Firstly, a modelling procedure is established, which allows the topological arrangement of the mechanical networks to be obtained by mapping the damping, inertance and stiffness effects directly to their respective hydraulic counterparts. Secondly, an experimental sequence is followed, which separates the identification of friction, stiffness and various damping effects. Furthermore, an experimental set-up is introduced, where two pressure gauges are used to accurately measure the pressure drop across the external tube. The theoretical models with improved confidence are obtained using the proposed methodology for a helical-tube fluid inerter prototype. The sources of remaining discrepancies are further analysed.

  3. Assessing exergy of forest ecosystem using airborne and satellite data

    Science.gov (United States)

    Brovkina, Olga; Fabianek, Tomas; Lukes, Petr; Zemek, Frantisek

    2017-04-01

    Interactions of the energy flows of forest ecosystem with environment are formed by a suite of forest structure, functions and pathways of self-control. According to recent thermodynamic theory for open systems, concept of exergy of solar radiation has been applied to estimate energy consumptions on evapotranspiration and biomass production in forest ecosystem or to indicate forest decline and human land use impact on ecosystem stability. However, most of the methods for exergy estimation in forest ecosystem is not stable and its physical meaning remains on the surface. This study was aimed to contribute to understanding the exergy of forest ecosystem using combination of remote sensing (RS) and eddy covariance technologies, specifically: 1/to explore exergy of solar radiation depending on structure of solar spectrum (number of spectral bands of RS data), and 2/to explore the relationship between exergy and flux tower eddy covariance measurements. Two study forest sites were located in Western Beskids in the Czech Republic. The first site was dominated by young Norway spruce, the second site was dominated by mature European beech. Airborne hyperspectral data in VNIR, SWIR and TIR spectral regions were acquired 9 times for study sites during a vegetation periods in 2015-2016. Radiometric, geometric and atmospheric corrections of airborne data were performed. Satellite multispectral Landsat-8 cloud-free 21 scenes were downloaded and atmospherically corrected for the period from April to November 2015-2016. Evapotranspiration and latent heat fluxes were collected from operating flux towers located on study sites according to date and time of remote sensing data acquisition. Exergy was calculated for each satellite and airborne scene using various combinations of spectral bands as: Ex=E^out (K+ln E^out/E^in )+R, where Ein is the incoming solar energy, Eout is the reflected solar energy, R = Ein-Eout is absorbed energy, Eout/Ein is albedo and K is the Kullback increment

  4. Exergy analysis of aluminum recovery from municipal solid waste incineration

    DEFF Research Database (Denmark)

    Vyzinkarova, Dana; Allegrini, Elisa; Laner, D.

    Two main challenges, associated with the recovery of aluminum from state-of-the-art municipal solid waste (MSW) incineration plants, are yield as well as quality losses of metallic aluminum due to particle surface oxidation and presence of impurities. Yet, in the framework of life cycle assessment...... (LCA) a direct measure for expressing the quality of primary and secondary resources is missing. In view of a possible solution, exergy has been proposed as a concept to evaluate the quality of resources. In this paper, LCA and exergy analyses for two waste treatment approaches are conducted...... in parallel to each other, with a goal to evaluate the added value of exergy for LCA studies in the resource recovery context. The functional unit is the treatment of 1 ton MSW. Two alternative approaches for recovering aluminum from MSW directed to a waste-to-energy plant are considered. A) MSW is treated...

  5. Energy and Exergy Analyses of the Danish Industry Sector

    DEFF Research Database (Denmark)

    Bühler, Fabian; Nguyen, Tuong-Van; Elmegaard, Brian

    2016-01-01

    A detailed analysis of the Danish industry is presented in this paper using the energy and exergy methods. For the 22 most energy-intensive process industries, which represent about 80% of the total primary energy use of the industrial sector, detailed end-use models were created and analysed...... of using electricity and district heat in the industry is shown. The exergy efficiencies for each process industry were found to be in the range of 12% to 56% in 2012. However variations in the efficiencies within the sectors for individual process industries occur, underlining the need for detailed......, by determining the sectors losses and exergy destruction. In addition the importance of applying a system analysis is shown, which corrects the site efficiencies for electricity and district heating use. The use of 22 industries,further highlights differences amongst industries belonging to the same sector....

  6. EXERGY ANALYSIS OF GEOTHERMAL POWER PLANT KAMOJANG 68, 3 MW IN CAPACITY

    OpenAIRE

    Aziz, Amiral

    2018-01-01

    The importance of exergy analysis in preliminary design of geothermal power has been proven. An exergy analysis was carried out and the locations and quantities of exergy losses, wastes and destructions in the different processes of the plan were pinpointed. The obtained results show that the total exergy available from production wells KMJ 68 was calculated to be 6967.55 kW. The total exergy received from wells which is connected during the analysis and enter into the separator was found to ...

  7. Exergy analysis of the FIGUEIRA thermal power plant operation - state of Parana, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Stanescu, George; Lima, Joao E. [Parana Univ., Curitiba, PR (Brazil). Dept. de Engenharia Mecanica]. E-mails: stanescu@demec.ufpr.br; joeduli@demec.ufpr.br; Andrade, Carlos de [FIGUEIRA Thermal Power Plant, Figueira, PR (Brazil)]. E-mail: ccarlosaandrade@zipmail.com.br

    2000-07-01

    Exergy analysis is a powerful tool to evaluate, design and improve the thermal systems. The method of exergy analysis or availability analysis is well suited for furthering the goal of increasing the efficiency of existing power generation systems, and the capability of more effective energy resource use. Exergy analysis of the FIGUEIRA thermal power plant is presented. Exergy losses occurring in various components are considered and the exergy balance is shown in tabular form. Results clearly reveal that the steam generator is the principal site of thermodynamic losses, while the condenser is relatively unimportant. (author)

  8. Base fluid in improving heat transfer for EV car battery

    Science.gov (United States)

    Bin-Abdun, Nazih A.; Razlan, Zuradzman M.; Shahriman, A. B.; Wan, Khairunizam; Hazry, D.; Ahmed, S. Faiz; Adnan, Nazrul H.; Heng, R.; Kamarudin, H.; Zunaidi, I.

    2015-05-01

    This study examined the effects of base fluid (as coolants) channeling inside the heat exchanger in the process of the increase in thermal conductivity between EV car battery and the heat exchanger. The analysis showed that secondary cooling system by means of water has advantages in improving the heat transfer process and reducing the electric power loss on the form of thermal energy from batteries. This leads to the increase in the efficiency of the EV car battery, hence also positively reflecting the performance of the EV car. The present work, analysis is performed to assess the design and use of heat exchanger in increasing the performance efficiency of the EV car battery. This provides a preface to the use this design for nano-fluids which increase and improve from heat transfer.

  9. Fluid-based radon mitigation technology development for industrial applications

    International Nuclear Information System (INIS)

    Liu, K.V.; Gabor, J.D.; Holtz, R.E.; Gross, K.C.

    1996-01-01

    The objective of the radon mitigation technology development effort is to develop an efficient and economical radon gas removal technology based on a fluid absorption process. The technology must be capable of cleaning up a wide range of radon gas stream concentrations to a level that meets EPA gas emission standards for residential and industrial applications. Argonne has recently identified a phenomenon that offers the possibility of radon recovery from the atmosphere with high efficiency at room temperature, and radon release at slightly elevated temperatures (50-60 degrees C.) such a device would offer numerous substantial advantages over conventional cryogenic charcoal systems for the removal of radon. Controlled sources of radon in Argonne's radon research facility are being used to quantitatively assess the performance of a selected class of absorbing fluids over a range of radon concentrations. This paper will discuss the design of laboratory- and engineering-scale radon absorption units and present some preliminary experimental test results

  10. High viscosity fluid simulation using particle-based method

    KAUST Repository

    Chang, Yuanzhang

    2011-03-01

    We present a new particle-based method for high viscosity fluid simulation. In the method, a new elastic stress term, which is derived from a modified form of the Hooke\\'s law, is included in the traditional Navier-Stokes equation to simulate the movements of the high viscosity fluids. Benefiting from the Lagrangian nature of Smoothed Particle Hydrodynamics method, large flow deformation can be well handled easily and naturally. In addition, in order to eliminate the particle deficiency problem near the boundary, ghost particles are employed to enforce the solid boundary condition. Compared with Finite Element Methods with complicated and time-consuming remeshing operations, our method is much more straightforward to implement. Moreover, our method doesn\\'t need to store and compare to an initial rest state. The experimental results show that the proposed method is effective and efficient to handle the movements of highly viscous flows, and a large variety of different kinds of fluid behaviors can be well simulated by adjusting just one parameter. © 2011 IEEE.

  11. A MEMS SOI-based piezoresistive fluid flow sensor

    Science.gov (United States)

    Tian, B.; Li, H. F.; Yang, H.; Song, D. L.; Bai, X. W.; Zhao, Y. L.

    2018-02-01

    In this paper, a SOI (silicon-on-insulator)-based piezoresistive fluid flow sensor is presented; the presented flow sensor mainly consists of a nylon sensing head, stainless steel cantilever beam, SOI sensor chip, printed circuit board, half-cylinder gasket, and stainless steel shell. The working principle of the sensor and some detailed contrastive analysis about the sensor structure were introduced since the nylon sensing head and stainless steel cantilever beam have distinct influence on the sensor performance; the structure of nylon sensing head and stainless steel cantilever beam is also discussed. The SOI sensor chip was fabricated using micro-electromechanical systems technologies, such as reactive ion etching and low pressure chemical vapor deposition. The designed fluid sensor was packaged and tested; a calibration installation system was purposely designed for the sensor experiment. The testing results indicated that the output voltage of the sensor is proportional to the square of the fluid flow velocity, which is coincident with the theoretical derivation. The tested sensitivity of the sensor is 3.91 × 10-4 V ms2/kg.

  12. The exploitation of the physical exergy of liquid natural gas by closed power thermodynamic cycles. An overview

    International Nuclear Information System (INIS)

    Invernizzi, Costante M.; Iora, Paolo

    2016-01-01

    The world trade in LNG (liquefied natural gas) has tripled in the last 15 years and the forecasts are for its further rapid expansion. Although the cryogenic exergy of the LNG could be used in many industrial processes, it is recognized also as a source for power cycles. When using the low temperature capacity of LNG for power production, several thermodynamic cycles can be considered. This paper reports the state-of-the art of the most relevant solutions based on conventional and non-conventional thermodynamic closed cycles. Moreover, a novel metrics framework, suitable for a fairer comparison among the energy recovery performances of the different technologies is proposed. According to the defined indicators the compounds plants with gas turbine and closed Brayton cycles perform really better, with an almost full use of LNG available cold temperature and a fuel consumption with an efficiency better than that of the current combined cycles. The Rankine cycles with organic working fluids (pure fluids or non-azeotropic mixtures) using seawater or heat available at low temperature (for instance at 150 °C) also perform in a very satisfactory way. Real gas Brayton cycles and carbon dioxide condensation cycles work with very good thermal efficiency also at relatively low maximum temperatures (300 ÷ 600 °C) and could have peculiar applications. - Highlights: • A review of systems for the combined re-gasification of LNG and generation of power. • The considered systems are: closed Brayton cycles, condensation cycles, gas turbines. • Definition of new parameters for an energy assessment of the systems? performances. • A comparison among the various systems from the energy point of view.

  13. Exergy analysis of a solar-powered vacuum membrane distillation unit using two models

    International Nuclear Information System (INIS)

    Miladi, Rihab; Frikha, Nader; Gabsi, Slimane

    2017-01-01

    A detailed exergy analysis of a solar powered VMD unit was performed using two models: the ideal mixture model and the model using the thermodynamics properties of seawater. The exergy flow rates of process steam, given by the two models differed of about 18%, on average. Despite these differences, the two models agree that during the step of condensation, the most important fraction of exergy was destroyed. Moreover, in this work, two forms of exergy efficiency are calculated. The overall exergy efficiency of the unit with reference to the exergy collected by the solar collector was 3.25% and 2.30% according to Cerci and Sharqawy models, respectively. But, it was 0.182% and 0.128%, when referenced to the exergy of solar radiation, according to Cerci and Sharqawy models, respectively. Besides, the utilitarian exergy efficiency was 9.96%. Since the heat exchanger, the hollow-fiber module and the condenser have a very high exergy performance, then it can be concluded that the enhancement or reduction of exergy losses will be mainly by recovering heat lost in brine discharges and in the rejection of the cooling water. In addition, the influence of the rejection rate on exergy efficiencies was studied. - Highlights: • Two exergy models were compared using a VMD plant dataset. • Two forms of exergy efficiency were evaluated and discussed. • The components responsible for the biggest losses in the system were identified. • The direction for performance enhancement of the desalination device was pointed out. • The influence of the rejection rate on exergy efficiencies was studied.

  14. Exergy analysis of wine production: Red wine production process as a case study

    International Nuclear Information System (INIS)

    Genc, Mahmut; Genc, Seda; Goksungur, Yekta

    2017-01-01

    Highlights: • Red wine production process was studied thermodynamically by exergy analysis method. • The first study on exergetic analysis of a red wine production process. • Energetic and exergetic efficiencies are calculated as 57.2 and 41.8%, respectively. • Cumulative exergy loss is computed as 2692.51 kW for 1 kg/s grape. • Specific exergy loss is found as 5080.20 kW/kg wine. - Abstract: This paper performs exergy analysis of a red wine production line and defines the exergy destruction rates to assess the system performance in terms of sustainability. A model study with necessary data is chosen for the calculations. The total exergy destruction rate of the overall system was determined to be 344.08 kW while the greatest destruction rate of the exergy in the whole system occurred in the open fermenter (333.6 kW). The system thermal efficiency was obtained to be 57.2% while the exergy efficiency was calculated as 41.8%. The total exergy destruction rate of the overall system increases with the increase both in the grape flow rate and the reference temperature when the reference pressure is assumed as 101.325 kPa. Furthermore, the chemical exergy of streams was found much higher than the physical exergy for each stream. The exergy results were illustrated through the Grassmann diagram. Furthermore, cumulative exergy loss and specific exergy loss values were determined as 2692.51 kW/1 kg/s grape processed and 5080.20 kW/kg wine, respectively.

  15. Morphing-Based Shape Optimization in Computational Fluid Dynamics

    Science.gov (United States)

    Rousseau, Yannick; Men'Shov, Igor; Nakamura, Yoshiaki

    In this paper, a Morphing-based Shape Optimization (MbSO) technique is presented for solving Optimum-Shape Design (OSD) problems in Computational Fluid Dynamics (CFD). The proposed method couples Free-Form Deformation (FFD) and Evolutionary Computation, and, as its name suggests, relies on the morphing of shape and computational domain, rather than direct shape parameterization. Advantages of the FFD approach compared to traditional parameterization are first discussed. Then, examples of shape and grid deformations by FFD are presented. Finally, the MbSO approach is illustrated and applied through an example: the design of an airfoil for a future Mars exploration airplane.

  16. More efficient mushroom canning through pinch and exergy analysis

    NARCIS (Netherlands)

    Paudel, Ekaraj; Sman, van der Ruud G.M.; Westerik, Nieke; Awasthi, Ashutosh; Dewi, Belinda P.C.; Boom, Remko M.

    2017-01-01

    Conventional production of canned mushrooms involves multiple processing steps as vacuum hydration, blanching, sterilization, etc. that are intensive in energy and water usage. We analyzed the current mushroom processing technique plus three alternative scenarios via pinch and exergy analysis.

  17. Thermodynamic optimization of heat exchanger tanks by exergy ...

    African Journals Online (AJOL)

    The paper introduces heat exchanger tanks, detailing their dominant thermodynamic relations to obtain the exergy analysis relations of heat exchanger tanks. Heat exchanger tank is examined under various laboratory conditions, including the power of heat element inside the tank, mass flow rate of cooling water of tank ...

  18. Exergy analysis of an IGCC design configuration for Plant Wansley

    International Nuclear Information System (INIS)

    Tsatsaronis, G.; Tawfik, T.; Lin, L.; Gallaspy, D.T.

    1989-01-01

    An integrated gasification-combined-cycle power plant design was developed for Georgia Power Company's Plant Wansley. This paper discusses the plant configuration and presents the most important results obtained from a detailed exergy analysis of the plant design. This analysis will be completed in a subsequent paper through an exergoeconomic analysis to identify design improvements for reducing the electricity cost

  19. Evaluation of seasonal exergy efficiency of air handing unit

    Directory of Open Access Journals (Sweden)

    Kęstutis Genys

    2015-10-01

    Full Text Available The article deals with the air handling unit seasonal exergy efficiency. TRNSYS simulation tool is used to evaluate it. The object of research is air treatment device used to treat an air for the ventilation of laboratory. The mathematical model of air handling unit using TRNSYS simulation tool was developed when the technical parameters of air handling unit and energy exchange in it were analysed. The developed model according to the made observations during the warm and cold periods was tested and validation of elements was performed. The simulation of air handling unit operation after the verification of reliability and permitted tolerances was performed. The control mechanisim which allows simulating the operation of air handling unit during cold and warm periods of the year was made. The mathematical algorithm for calculation of air handling unit exergy efficiency coefficient applying the principles of exergy analysis was developed. The seasonal exergy efficiency of air handling unit equal to 3.94 percent during the simulation was obtained.

  20. Energy and Exergy Performance of three FPSO Operational Modes

    DEFF Research Database (Denmark)

    Sánchez, Yamid Alberto Carranza; Junior, Silvio de Oliveira; da Silva, Julio Augusto Mendes

    2015-01-01

    by the FPSO operator. Energy and exergy criteria have been applied to evaluate and compare the performance of components and systems of the three operational modes of the FPSO. The processing and utilities plants have been modeled and simulated by using Aspen HYSYS®. Results indicate that higher oil content...

  1. Exergy optimization of cooling tower for HGSHP and HVAC applications

    International Nuclear Information System (INIS)

    Singh, Kuljeet; Das, Ranjan

    2017-01-01

    Highlights: • Development of new correlations for outlet parameters with all inlet parameters. • Simultaneous achievement of required heat load and minimum exergy destruction. • Multiple combinations of parameters found for same heat load at minimized exergy. • Study useful for optimum control of cooling tower under varying ambient conditions. • Generalized optimization study can be implemented for any mechanical cooling tower. - Abstract: In the present work, a constrained inverse optimization method for building cooling applications is proposed to control the mechanical draft wet cooling tower by minimizing the exergy destruction and satisfying an imposed heat load under varying environmental conditions. The optimization problem is formulated considering the cooling dominated heating, ventilation and air conditioning (HVAC) and hybrid ground source heat pump (HGSHP). As per the requirement, new second degree correlations for the tower outlet parameters (water temperature, air dry and wet-bulb temperatures) with five inlet parameters (dry-bulb temperature, relative humidity, water inlet temperature, water and air mass flow rates) are developed. The Box–Behnken design response surface method is implemented for developing the correlations. Subsequently, the constrained optimization problem is solved using augmented Lagrangian genetic algorithm. This work further developed optimum inlet parameters operating curves for the HGSHP and the HVAC systems under varying environmental conditions aimed at minimizing the exergy destruction along with the fulfillment of the required heat load.

  2. Energy and exergy analyses of malt drink production in Nigeria

    International Nuclear Information System (INIS)

    Fadare, D.A.; Nkpubre, D.O.; Oni, A.O.; Falana, A.; Waheed, M.A.; Bamiro, O.A.

    2010-01-01

    Energy requirements and exergy inefficiencies for processing of malt drink were estimated for a Nigerian brewery. The process was divided into twenty-one basic unit operations and grouped into four main group operations: silo house, brew house, filter room and packaging house. The energy intensity for processing a batch of 9.8 tonnes brew grains to 562 hl of malt drink was estimated as 261.63 MJ/hl consisting of electrical (41.01%), thermal (58.81%) and manual (0.19%) of the total energy. The most energy intensive group operation was the Packaging House operation, followed by the Brew House operation with energy intensities of 223.19 and 35.94 MJ/hl, respectively. The exergy analysis revealed that the packaging house operation was responsible for most of the inefficiency (92.16%) followed by brew house operation (7.17%) and the silo house and filter room operations with less than 1% of the total exergy lost. The most exergy loss took place in the pasteurizer, which accounted for 59.75% of the overall system inefficiency. Modification in the pasteurizer and use of spent grains as alternate source of energy in the steam boiler were recommended to improve the energy efficiency of the system.

  3. Energy and exergy analyses of malt drink production in Nigeria

    Energy Technology Data Exchange (ETDEWEB)

    Fadare, D.A.; Nkpubre, D.O.; Oni, A.O.; Falana, A.; Bamiro, O.A. [Mechanical Engineering Department, University of Ibadan, P. M.B. 1, Ibadan, Oyo State (Nigeria); Waheed, M.A. [Mechanical Engineering Department, University of Agriculture, P. M.B. 2240, Abeokuta, Ogun State (Nigeria)

    2010-12-15

    Energy requirements and exergy inefficiencies for processing of malt drink were estimated for a Nigerian brewery. The process was divided into twenty-one basic unit operations and grouped into four main group operations: silo house, brew house, filter room and packaging house. The energy intensity for processing a batch of 9.8 tonnes brew grains to 562 hl of malt drink was estimated as 261.63 MJ/hl consisting of electrical (41.01%), thermal (58.81%) and manual (0.19%) of the total energy. The most energy intensive group operation was the Packaging House operation, followed by the Brew House operation with energy intensities of 223.19 and 35.94 MJ/hl, respectively. The exergy analysis revealed that the packaging house operation was responsible for most of the inefficiency (92.16%) followed by brew house operation (7.17%) and the silo house and filter room operations with less than 1% of the total exergy lost. The most exergy loss took place in the pasteurizer, which accounted for 59.75% of the overall system inefficiency. Modification in the pasteurizer and use of spent grains as alternate source of energy in the steam boiler were recommended to improve the energy efficiency of the system. (author)

  4. Tailoring peritoneal dialysis fluid for optimal acid-base targets.

    Science.gov (United States)

    Feriani, Mariano

    2009-01-01

    Mild derangements of acid-base status are common features in peritoneal dialysis patients, metabolic acidosis being the most frequent alteration. One of the main tasks of dialysis is to correct these derangements and the target is the normalization of the acid-base parameters since they affect several organs and functions. Since factors affecting acid-base homeostasis are intrinsic characteristics of the individual patient (metabolic acid production, distribution space for bicarbonate, dialytic prescription, etc.), it is not surprising that only relatively few patients achieve the normal range. Only a certain modulation of buffer infusion by using different buffer concentrations in the dialysis fluid may ensure a good correction in a large percentage of patients.

  5. Fluid Analysis and Improved Structure of an ATEG Heat Exchanger Based on Computational Fluid Dynamics

    Science.gov (United States)

    Tang, Z. B.; Deng, Y. D.; Su, C. Q.; Yuan, X. H.

    2015-06-01

    In this study, a numerical model has been employed to analyze the internal flow field distribution in a heat exchanger applied for an automotive thermoelectric generator based on computational fluid dynamics. The model simulates the influence of factors relevant to the heat exchanger, including the automotive waste heat mass flow velocity, temperature, internal fins, and back pressure. The result is in good agreement with experimental test data. Sensitivity analysis of the inlet parameters shows that increase of the exhaust velocity, compared with the inlet temperature, makes little contribution (0.1 versus 0.19) to the heat transfer but results in a detrimental back pressure increase (0.69 versus 0.21). A configuration equipped with internal fins is proved to offer better thermal performance compared with that without fins. Finally, based on an attempt to improve the internal flow field, a more rational structure is obtained, offering a more homogeneous temperature distribution, higher average heat transfer coefficient, and lower back pressure.

  6. Assessment of energy and exergy efficiencies of a grate clinker cooling system through the optimization of its operational parameters

    International Nuclear Information System (INIS)

    Ahamed, J.U.; Madlool, N.A.; Saidur, R.; Shahinuddin, M.I.; Kamyar, A.; Masjuki, H.H.

    2012-01-01

    Grate coolers are widely used in cement industries to recover heat from hot clinker, coming out from the rotary kiln. This study focuses on improving the energy, exergy and recovery efficiencies of a grate cooling system through the optimization of its operational parameters such as masses of cooling air and clinker, cooling air temperature, and grate speed. It has been found that the energy and recovery energy efficiencies of a cooling system can be increased by 1.1% and 1.9%, respectively, with every 5% mass increases of cooling air. Similarly, it has been estimated that energy and recovery energy efficiencies can be increased by 2.0% and 0.4% with every 5% increase of cooling temperature. The exergy and its recovery efficiencies found to be increased by 3.6% and 2.2%, respectively, for the same condition. Energy efficiency and energy recovery efficiencies are increased by 3.5% and 1.4% with every 9.1% increase of grate speed. Using heat recovery from the exhaust air, energy and exergy recovery efficiencies of the cooling system found to be increased by 21.5% and 9.4%, respectively. It has been found that about 38.10% and 30.86% energy cost can be saved by changing mass flow rate of clinker and mass flow rate of cooling air, respectively. -- Highlights: ► The energy and exergy efficiencies of the base case clinker cooler are 81.2% and 53.7%, respectively. ► To increase 5% mass flow of cooling air, the energy and exergy efficiency increase 1.1% and 0.9%, respectively. ► Increase of grate speed and cooling air temperature cause to increase of all efficiencies. ► Heat recovery from the exhaust air experiences 21.5% and 9.4% in energy and exergy recovery efficiency, respectively. ► Reduction of clinker mass flow reduces the emission of NO x , CO, PM and CO 2 .

  7. Energy and Exergy Analysis of Ocean Compressed Air Energy Storage Concepts

    Directory of Open Access Journals (Sweden)

    Vikram C. Patil

    2018-01-01

    Full Text Available Optimal utilization of renewable energy resources needs energy storage capability in integration with the electric grid. Ocean compressed air energy storage (OCAES can provide promising large-scale energy storage. In OCAES, energy is stored in the form of compressed air under the ocean. Underwater energy storage results in a constant-pressure storage system which has potential to show high efficiency compared to constant-volume energy storage. Various OCAES concepts, namely, diabatic, adiabatic, and isothermal OCAES, are possible based on the handling of heat in the system. These OCAES concepts are assessed using energy and exergy analysis in this paper. Roundtrip efficiency of liquid piston based OCAES is also investigated using an experimental liquid piston compressor. Further, the potential of improved efficiency of liquid piston based OCAES with use of various heat transfer enhancement techniques is investigated. Results show that adiabatic OCAES shows improved efficiency over diabatic OCAES by storing thermal exergy in thermal energy storage and isothermal OCAES shows significantly higher efficiency over adiabatic and diabatic OCAES. Liquid piston based OCAES is estimated to show roundtrip efficiency of about 45% and use of heat transfer enhancement in liquid piston has potential to improve roundtrip efficiency of liquid piston based OCAES up to 62%.

  8. Offshore disposal of oil-based drilling fluid waste

    International Nuclear Information System (INIS)

    Malachosky, E.; Shannon, B.E.; Jackson, J.E.

    1991-01-01

    Offshore drilling operations in the Gulf of Mexico may use oil-based drilling fluids to mitigate drilling problems. The result is the generation of a significant quantity of oily cuttings and mud. The transportation of this waste for onshore disposal is a concern from a standpoint of both personnel safety and potential environmental impact. A process for preparing a slurry of this waste and the subsequent disposal of the slurry through annular pumping has been put into use by ARCO Oil and Gas Company. The disposal technique has been approved by the Minerals Management Service (MMS). The slurried waste is displaced down a casing annulus into a permeable zone at a depth below the surface casing setting depth. The annular disposal includes all cuttings and waste oil mud generated during drilling with oil-based fluids. This disposal technique negates the need for cuttings storage on the platform, transportation to shore, and the environmental effects of onshore surface disposal. The paper describes the environmental and safety concerns with onshore disposal, the benefits of annular disposal, and the equipment and process used for the preparation and pumping of the slurry

  9. Energy and exergy analysis of a new ejector enhanced auto-cascade refrigeration cycle

    International Nuclear Information System (INIS)

    Yan, Gang; Chen, Jiaheng; Yu, Jianlin

    2015-01-01

    Highlights: • A new ejector enhanced auto-cascade refrigeration cycle using R134a/R23 is proposed. • The performance of new and basic cycles is compared by simulation method. • The new cycle outperforms the basic cycle in both energetic and exergy aspects. • Both cycles have optimum mixture compositions to obtain optimal performance. - Abstract: A new ejector enhanced auto-cascade refrigeration cycle using R134a/R23 refrigerant mixture is proposed in this paper. In the new cycle, an ejector is used to recover part of the work that would otherwise be lost in the throttling processes. The performance comparison between the new cycle and a basic auto-cascade refrigeration cycle is carried out based on the first and second laws of thermodynamics. The simulation results show that both the coefficient of performance and exergy efficiency of the new cycle can be improved by 8.42–18.02% compared with those of the basic cycle at the same operation conditions as the ejector has achieved pressure lift ratios of 1.12–1.23. It is found that in the new cycle, the highest exergy destruction occurs in the compressor followed by the condenser, cascade condenser, expansion valve, ejector and evaporator. The effect of some main parameters on the cycle performance is further investigated. The results show that for the new cycle, the achieved performance improvement over the basic cycle is also dependent on the mixture composition and the vapor quality at the condenser outlet. The coefficient of performance improvement of the new cycle over the basic cycle degrades with increasing vapor quality. In addition, there exists an optimum mixture composition to obtain the maximum coefficient of performance for the new cycle when other operation conditions are given. The optimum mixture composition of both cycles may be fixed at about 0.5 under the given evaporating temperature.

  10. Reinforcement learning for optimal control of low exergy buildings

    International Nuclear Information System (INIS)

    Yang, Lei; Nagy, Zoltan; Goffin, Philippe; Schlueter, Arno

    2015-01-01

    Highlights: • Implementation of reinforcement learning control for LowEx Building systems. • Learning allows adaptation to local environment without prior knowledge. • Presentation of reinforcement learning control for real-life applications. • Discussion of the applicability for real-life situations. - Abstract: Over a third of the anthropogenic greenhouse gas (GHG) emissions stem from cooling and heating buildings, due to their fossil fuel based operation. Low exergy building systems are a promising approach to reduce energy consumption as well as GHG emissions. They consists of renewable energy technologies, such as PV, PV/T and heat pumps. Since careful tuning of parameters is required, a manual setup may result in sub-optimal operation. A model predictive control approach is unnecessarily complex due to the required model identification. Therefore, in this work we present a reinforcement learning control (RLC) approach. The studied building consists of a PV/T array for solar heat and electricity generation, as well as geothermal heat pumps. We present RLC for the PV/T array, and the full building model. Two methods, Tabular Q-learning and Batch Q-learning with Memory Replay, are implemented with real building settings and actual weather conditions in a Matlab/Simulink framework. The performance is evaluated against standard rule-based control (RBC). We investigated different neural network structures and find that some outperformed RBC already during the learning phase. Overall, every RLC strategy for PV/T outperformed RBC by over 10% after the third year. Likewise, for the full building, RLC outperforms RBC in terms of meeting the heating demand, maintaining the optimal operation temperature and compensating more effectively for ground heat. This allows to reduce engineering costs associated with the setup of these systems, as well as decrease the return-of-invest period, both of which are necessary to create a sustainable, zero-emission building

  11. Advanced exergy analysis on a modified auto-cascade freezer cycle with an ejector

    International Nuclear Information System (INIS)

    Bai, Tao; Yu, Jianlin; Yan, Gang

    2016-01-01

    This paper presents a study on a modified ejector enhanced auto-cascade freezer cycle with conventional thermodynamic and advanced exergy analysis methods. The energetic analysis shows that the modified cycle exhibits better performance than the conventional auto-cascade freezer cycle, and the system COP and volumetric refrigeration capacity could be improved by 19.93% and 28.42%. Furthermore, advanced exergy analysis is adopted to better evaluate the performance of the proposed cycle. The exergy destruction within a system component is split into endogenous/exogenous and unavoidable/avoidable parts in the advanced exergy analysis. The results show that the compressor with the largest avoidable endogenous exergy destruction has highest improvement priority, followed by the condenser, evaporator and ejector, which is different from the conclusion obtained from the conventional exergy analysis. The evaporator/condenser greatly affects the exogenous exergy destruction within the system components, and the compressor has large impact on the exergy destruction within the condenser. Improving the efficiencies of the compressor efficiency and the ejector could effectively reduce the corresponding avoidable endogenous exergy destruction. The exergy destruction within the evaporator almost entirely belongs to the endogenous part, and reducing the temperature difference at the evaporator is the main approach of reducing its exergy destruction. - Highlights: • A modified ejector enhanced auto-cascade freezer cycle is proposed. • Conventional and advanced exergy analyses are performed in this study. • Compressor should be firstly improved first, followed by condenser and evaporator. • Interactions among the system components are assessed with advanced exergy analysis.

  12. Acoustic Velocity and Attenuation in Magnetorhelogical fluids based on an effective density fluid model

    Directory of Open Access Journals (Sweden)

    Shen Min

    2016-01-01

    Full Text Available Magnetrohelogical fluids (MRFs represent a class of smart materials whose rheological properties change in response to the magnetic field, which resulting in the drastic change of the acoustic impedance. This paper presents an acoustic propagation model that approximates a fluid-saturated porous medium as a fluid with a bulk modulus and effective density (EDFM to study the acoustic propagation in the MRF materials under magnetic field. The effective density fluid model derived from the Biot’s theory. Some minor changes to the theory had to be applied, modeling both fluid-like and solid-like state of the MRF material. The attenuation and velocity variation of the MRF are numerical calculated. The calculated results show that for the MRF material the attenuation and velocity predicted with this effective density fluid model are close agreement with the previous predictions by Biot’s theory. We demonstrate that for the MRF material acoustic prediction the effective density fluid model is an accurate alternative to full Biot’s theory and is much simpler to implement.

  13. Thermodynamic performance assessment of a novel environmentally-benign solar energy based integrated system

    International Nuclear Information System (INIS)

    Yuksel, Yunus Emre; Ozturk, Murat; Dincer, Ibrahim

    2016-01-01

    Highlights: • Development of a novel solar energy based system for multigenaration applications. • Evaluation of the exergy efficiency and destruction rate in each system component. • Investigation of the varying operating conditions on the system performance. • Evaluation of complete parametric studies and performance analysis of the system. - Abstract: In this paper, a novel solar energy based multigeneration system for producing electricity, hydrogen, hot water, heating and cooling is presented and analyzed thermodynamically for potential applications. The energy and exergy analyses are conducted for entire system and its sub-systems, which are a parabolic trough collector system, a double-stage organic Rankine cycle, a proton exchange membrane electrolyzer, a PEM fuel cycle and a quadruple effect absorption cooling system. The parametric studies are performed in order to indicate the impacts of some key indicators on the integrated system performance. These analyses are simulated by using the Engineering Equation Solver software. The results show that the increase in ambient temperature increases the exergetic coefficient performance of the Quadruple Effect Absorption Cooling System. In addition, the increase in solar intensity, temperature of absorber pipes inner surface and concentration of ammonia in working fluid mixture has the positive effect on produced electricity from the expanders and turbine, and hydrogen from the PEM electrolyzer. According to exergy analyses, the largest exergy destruction rates are obtained in the parabolic trough collector, PEM fuel cell and turbine. Therefore, any improvements in these components would lead to a better efficiency of the integrated system.

  14. Thermodynamic assessment of integrated biogas-based micro-power generation system

    International Nuclear Information System (INIS)

    Hosseini, Seyed Ehsan; Barzegaravval, Hasan; Wahid, Mazlan Abdul; Ganjehkaviri, Abdolsaeid; Sies, Mohsin Mohd

    2016-01-01

    Highlights: • A thermodynamic modelling of an integrated biogas-based micro-power generation system is reported. • The impact of design parameters on the thermodynamic performance of the system is evaluated. • High turbine inlet temperatures lead the system to the higher energy and exergy efficiency and higher power generation. • Enhancement of GT isentropic efficiency incurs negative effects on the performance of air preheater and heat exchanger. • The rate of power generation increases by the enhancement of steam turbine pressure in ORC. - Abstract: In this paper, a thermodynamic modelling of an integrated biogas (60%CH_4 + 40%CO_2) micro-power generation system for electricity generation is reported. This system involves a gas turbine cycle and organic Rankine cycle (ORC) where the wasted heat of gas turbine cycle is recovered by closed ORC. The net output power of the micro-power generation system is fixed at 1.4 MW includes 1 MW power generated by GT and 0.4 MW by ORC. Energy and exergy assessments and related parametric studies are carried out, and parameters that influence on energy and exergy efficiency are evaluated. The performance of the system with respect to variation of design parameters such as combustion air inlet temperature, turbine inlet temperature, compressor pressure ratio, gas turbine isentropic efficiency and compressor isentropic efficiency (from the top cycle) and steam turbine inlet pressure, and condenser pressure (from bottoming cycle) is evaluated. The results reveal that by the increase of gas turbine isentropic efficiency, the outlet temperature of gas turbine decreases which incurs negative impacts on the performance of air preheater and heat exchanger, however the energy and exergy efficiency increases in the whole system. By the increase of air compressor pressure ratio, the energy and exergy of the combined cycle decreases. The exergy efficiency of ORC alters by the variation of gas turbine parameters which can be

  15. Fluid model of inductively coupled plasma etcher based on COMSOL

    International Nuclear Information System (INIS)

    Cheng Jia; Ji Linhong; Zhu Yu; Shi Yixiang

    2010-01-01

    Fluid dynamic models are generally appropriate for the investigation of inductively coupled plasmas. A commercial ICP etcher filled with argon plasma is simulated in this study. The simulation is based on a multiphysical software, COMSOL(TM), which is a partial differential equation solver. Just as with other plasma fluid models, there are drift-diffusion approximations for ions, the quasi-neutrality assumption for electrons movements, reduced Maxwell equations for electromagnetic fields, electron energy equations for electron temperatures and the Navier-Stokes equation for neutral background gas. The two-dimensional distribution of plasma parameters are shown at 200 W of power and 1.33 Pa (10 mTorr) of pressure. Then the profile comparison of the electron number density and temperature with respect to power is illustrated. Finally we believe that there might be some disagreement between the predicted values and the real ones, and the reasons for this difference would be the Maxwellian eedf assumption and the lack of the cross sections of collisions and the reaction rates. (semiconductor physics)

  16. A fluid density sensor based on a resonant tube

    International Nuclear Information System (INIS)

    Zhu, Yong; Dao, Dzung Viet; Woodfield, Peter

    2014-01-01

    A fluid density sensor based on resonance frequency change of a metallic tube is presented. The sensor has been developed without using a complex micro-fabrication process. The sensor is able to identify fluid types/contaminations and improve the performance by reducing testing time, decreasing complexity of testing equipment and reducing sample sizes. The sensor can measure the resonance frequency of its own structure and determine the change in resonance frequency due to the subsequent sample inside the tube. Numerical modelling, analytical modelling and physical testing of a prototype sensor showed comparable results for both the magnitude and resonance frequency shift. The modelling results yielded a resonance frequency shift of 200 Hz from 9.87 kHz to 9.67 kHz after the water was filled into the tube. The actual testing illustrated a resonance frequency change of 280 Hz from 9.11 kHz to 8.83 kHz. The ultimate aim of the work is to determine resonance frequencies of desired samples at a level that could detect genetic disease on a cellular level. (paper)

  17. [Present status and trend of heart fluid mechanics research based on medical image analysis].

    Science.gov (United States)

    Gan, Jianhong; Yin, Lixue; Xie, Shenghua; Li, Wenhua; Lu, Jing; Luo, Anguo

    2014-06-01

    With introduction of current main methods for heart fluid mechanics researches, we studied the characteristics and weakness for three primary analysis methods based on magnetic resonance imaging, color Doppler ultrasound and grayscale ultrasound image, respectively. It is pointed out that particle image velocity (PIV), speckle tracking and block match have the same nature, and three algorithms all adopt block correlation. The further analysis shows that, with the development of information technology and sensor, the research for cardiac function and fluid mechanics will focus on energy transfer process of heart fluid, characteristics of Chamber wall related to blood fluid and Fluid-structure interaction in the future heart fluid mechanics fields.

  18. Role of exergy in increasing efficiency and sustainability and reducing environmental impact

    International Nuclear Information System (INIS)

    Rosen, Marc A.; Dincer, Ibrahim; Kanoglu, Mehmet

    2008-01-01

    The use of exergy is described as a measure for identifying and explaining the benefits of sustainable energy and technologies, so the benefits can be clearly understood and appreciated by experts and non-experts alike, and the utilization of sustainable energy and technologies can be increased. Exergy can be used to assess and improve energy systems, and can help better understand the benefits of utilizing green energy by providing more useful and meaningful information than energy provides. Exergy clearly identifies efficiency improvements and reductions in thermodynamic losses attributable to more sustainable technologies. A new sustainability index is developed as a measure of how exergy efficiency affects sustainable development. Exergy can also identify better than energy the environmental benefits and economics of energy technologies. The results suggest that exergy should be utilized by engineers and scientists, as well as decision and policy makers, involved in green energy and technologies in tandem with other objectives and constraints

  19. Analysis of cumulative exergy losses in the chains of technological processes

    International Nuclear Information System (INIS)

    Szargut, J.

    1989-01-01

    This paper reports on cumulative exergy consumption (CExC) which characterizes the chain of technological processes leading from natural resources to the final product under consideration. The difference of CExC and exergy of material or energy carrier expresses the cumulative exergy loss (CExL) in the mentioned technological chain. Two apportionment methods of CExL have been proposed. Partial exergy losses appear in particular links of the technological chain and characterize the influence of irreversibility of these links. Constituent exergy losses express the influence of thermodynamic imperfection of constituent technological chains leading to the final link of the total technological chain. Analysis of the partial and constituent exergy losses informs about the possibilities of improvement of the technological chains

  20. Subjective thermal sensation and human body exergy consumption rate: analysis and correlation

    DEFF Research Database (Denmark)

    Simone, Angela; Dovjak, M.; Kolarik, Jakub

    2011-01-01

    , it is reasonable to consider both the exergy flows in building and those within the human body. There is a need to verify the human-body exergy model with the Thermal-Sensation (TS) response of subjects exposed to different combinations of indoor climate parameters (temperature, humidity, etc.). First results...... available on the relation between human-body exergy consumption rates and subjectively assessed thermal sensation showed that the minimum human body exergy consumption rate is associated with thermal sensation votes close to thermal neutrality, tending to slightly cool side of thermal sensation. By applying...... the exergy concept to the built indoor environment, additional results are going to be explored. By using the data available so far of operative temperature (to), the human body exergy consumption rates increase as to increases above 24°C or decreases below 22°C at relative humidity (RH) lower than 50...

  1. An investigation on the assessed thermal sensation and human body exergy consumption rate

    DEFF Research Database (Denmark)

    Simone, Angela; Kolarik, Jakub; Iwamatsu, Toshiya

    2010-01-01

    perception of the indoor environment is rare. As the building should provide healthy and comfortable environment for its occupants, it is reasonable to consider both the exergy flows in the building and within the human body. A relatively new approach of the relation between the exergy concept and the built......-environment research has been explored in the present work. The relationship of subjectively assessed thermal sensation data, from earlier thermal comfort studies, to the calculated human-body exergy consumption has been analysed. The results show that the minimum human body exergy consumption rate was related......The exergy concept helps to optimize indoor climate conditioning systems to meet the requirements of sustainable building design. While the exergy approach to design and operation of indoor climate conditioning systems is relatively well established, its exploitation in connection to human...

  2. A relation between calculated human body exergy consumption rate and subjectively assessed thermal sensation

    DEFF Research Database (Denmark)

    Simone, Angela; Kolarik, Jakub; Iwamatsu, Toshiya

    2011-01-01

    occupants, it is reasonable to consider both the exergy flows in building and those within the human body. Until now, no data have been available on the relation between human-body exergy consumption rates and subjectively assessed thermal sensation. The objective of the present work was to relate thermal...... sensation data, from earlier thermal comfort studies, to calculated human-body exergy consumption rates. The results show that the minimum human body exergy consumption rate is associated with thermal sensation votes close to thermal neutrality, tending to the slightly cool side of thermal sensation....... Generally, the relationship between air temperature and the exergy consumption rate, as a first approximation, shows an increasing trend. Taking account of both convective and radiative heat exchange between the human body and the surrounding environment by using the calculated operative temperature, exergy...

  3. Personal Computer (PC) based image processing applied to fluid mechanics

    Science.gov (United States)

    Cho, Y.-C.; Mclachlan, B. G.

    1987-01-01

    A PC based image processing system was employed to determine the instantaneous velocity field of a two-dimensional unsteady flow. The flow was visualized using a suspension of seeding particles in water, and a laser sheet for illumination. With a finite time exposure, the particle motion was captured on a photograph as a pattern of streaks. The streak pattern was digitized and processed using various imaging operations, including contrast manipulation, noise cleaning, filtering, statistical differencing, and thresholding. Information concerning the velocity was extracted from the enhanced image by measuring the length and orientation of the individual streaks. The fluid velocities deduced from the randomly distributed particle streaks were interpolated to obtain velocities at uniform grid points. For the interpolation a simple convolution technique with an adaptive Gaussian window was used. The results are compared with a numerical prediction by a Navier-Stokes computation.

  4. VIBRATION ANALYSIS OF TURBINE BASED ON FLUID-STRUCTURE COUPLING

    Institute of Scientific and Technical Information of China (English)

    LIU Demin; LIU Xiaobing

    2008-01-01

    The vibration of a Francis turbine is analyzed with the additional quality matrix method based on fluid-structure coupling (FSC). Firstly, the vibration frequency and mode of blade and runner in air and water are calculated. Secondly, the influences to runner frequency domain by large flow, small flow and design flow working conditions are compared. Finally the influences to runner modes by centrifugal forces under three rotating speeds of 400 r/min, 500 r/min and 600 r/min are compared. The centrifugal force and small flow working condition have greatly influence on the vibration of small runner. With the increase of centrifugal force, the vibration frequency of the runner is sharply increased. Some order frequencies are even close to the runner natural frequency in the air. Because the low frequency vibration will severely damage the stability of the turbine, low frequency vibration of units should be avoided as soon as possible.

  5. Propositions for a PDF model based on fluid particle acceleration

    International Nuclear Information System (INIS)

    Minier, J.P.; Pozorski, J.

    1997-05-01

    This paper describes theoretical propositions to model the acceleration of a fluid particle in a turbulent flow. Such a model is useful for the PDF approach to turbulent reactive flows as well as for the Lagrangian modelling of two-phase flows. The model developed here draws from ideas already put forward by Sawford but which are generalized to the case of non-homogeneous flows. The model is built so as to revert continuously to Pope's model, which uses a Langevin equation for particle velocities, when the Reynolds number becomes very high. The derivation is based on the technique of fast variable elimination. This technique allow a careful analysis of the relations between different levels of modelling. It also allows to address certain problems in a more rigorous way. In particular, application of this technique shows that models presently used can in principle simulate bubbly flows including the pressure-gradient and added-mass forces. (author)

  6. Energy and exergy analyses of Photovoltaic/Thermal flat transpired collectors: Experimental and theoretical study

    International Nuclear Information System (INIS)

    Gholampour, Maysam; Ameri, Mehran

    2016-01-01

    Highlights: • A Photovoltaic/Thermal flat transpired collector was theoretically and experimentally studied. • Performance of PV/Thermal flat transpired plate was evaluated using equivalent thermal, first, and second law efficiencies. • According to the actual exergy gain, a critical radiation level was defined and its effect was investigated. • As an appropriate tool, equivalent thermal efficiency was used to find optimum suction velocity and PV coverage percent. - Abstract: PV/Thermal flat transpired plate is a kind of air-based hybrid Photovoltaic/Thermal (PV/T) system concurrently producing both thermal and electrical energy. In order to develop a predictive model, validate, and investigate the PV/Thermal flat transpired plate capabilities, a prototype was fabricated and tested under outdoor conditions at Shahid Bahonar University of Kerman in Kerman, Iran. In order to develop a mathematical model, correlations for Nusselt numbers for PV panel and transpired plate were derived using CFD technique. Good agreement was obtained between measured and simulated values, with the maximum relative root mean square percent deviation (RMSE) being 9.13% and minimum correlation coefficient (R-squared) 0.92. Based on the critical radiation level defined in terms of the actual exergy gain, it was found that with proper fan and MPPT devices, there is no concern about the critical radiation level. To provide a guideline for designers, using equivalent thermal efficiency as an appropriate tool, optimum values for suction velocity and PV coverage percent under different conditions were obtained.

  7. Thermodynamic and economic optimizations of a waste heat to power plant driven by a subcritical ORC (Organic Rankine Cycle) using pure or zeotropic working fluid

    International Nuclear Information System (INIS)

    Le, Van Long; Kheiri, Abdelhamid; Feidt, Michel; Pelloux-Prayer, Sandrine

    2014-01-01

    This paper carried out the thermodynamic and economic optimizations of a subcritical ORC (Organic Rankine Cycle) using a pure or a zeotropic mixture working fluid. Two pure organic compounds, i.e. n-pentane and R245fa, and their mixtures with various concentrations were used as ORC working fluid for this study. Two optimizations, i.e. exergy efficiency maximization and LCOE (Levelized Cost of Electricity) minimization, were performed to find out the optimum operating conditions of the system and to determine the best working fluid from the studied media. Hot water at temperature of 150 °C and pressure of 5 bars was used to simulate the heat source medium. Whereas, cooling water at temperature of 20 °C was considered to be the heat sink medium. The mass flow rate of heat source is fixed at 50 kg/s for the optimizations. According to the results, the n-pentane-based ORC showed the highest maximized exergy efficiency (53.2%) and the lowest minimized LCOE (0.0863 $/kWh). Regarding ORCs using zeotropic working fluids, 0.05 and 0.1 R245fa mass fraction mixtures present the comparable economic features and thermodynamic performances to the system using n-pentane at minimum LCOE. The ORC using R245fa represents the least profitable system. - Highlights: • Thermoeconomic optimization is carried out for a subcritical ORC. • Exergy efficiency and Levelized Cost of Electricity are optimized. • R245fa, n-Pentane and their mixtures are used as ORC working fluid. • CO 2 emissions can be substantially reduced by waste heat recovery using an ORC

  8. Magnetorheological fluid based on thixotropic PTFE-oil organogel

    Science.gov (United States)

    Zhang, Hansong; Yan, Hua; Hu, Zhide; Yang, Jianjian; Niu, Fanghao

    2018-04-01

    Polytetrafluoroethylene (PTFE) micropowders were employed in this work to fabricate PTFE-oil organogel, then carbonyl iron particles were dispersed in this thixotropic organogel to prepare magnetorheological fluids without any other additives. By performing a comparative investigation of MRFs' performances, enhanced magnetorheological response, suspension stability and tribological performance were obtained contrast to pure silicon oil based MRFs. The experimental results revealed a changeable viscosity of organogel, considerable increases in thixotropy also can be observed with the increase of PTFE content. Sedimentation tests demonstrated a much better suspension stability of MRFs based on organogel, suggesting that the internal network microstructures formed by hydrogen bonds between PTFE microparticles and oil molecular chains are likely to impose the gaps among magnetic particles thus hinder the particle aggregation and sedimentation. Moreover, a critical PTFE volume fraction about 4.7 vol% was recognized in this study, lower content organogels tended to display enhanced yield stresses contrast to pure silicon oil based MRFs while high content organogels showed slightly lower ones. It may suggest a compromise between nonmagnetic particle adsorption and the reinforcement effect of network microstructures. The adsorption is likely to decrease the saturation magnetization of carbonyl iron particles and to hinder the formation of field-induced chains, however, the reinforcement effect tends to strengthen these magnetic chains. Besides, the tribological tests confirmed the lubricant effects of PTFE-oil organogel by acquiring rather sharp decreases in friction coefficients of organogel based MRFs especially in the presence of magnetic field.

  9. Framework for analysis of solar energy systems in the built environment from an exergy perspective

    OpenAIRE

    Torio, H.; Schmidt, D.

    2010-01-01

    Exergy analysis is a more powerful tool than mere energy analysis for showing the improvement potential of energy systems. Direct use of solar radiation instead of degrading other high quality energy resources found in nature is advantageous. Yet, due to physical inconsistencies present in the exergy analysis framework for assessing direct-solar systems commonly found in literature, high exergy losses arise in the conversion process of solar radiation in direct-solar systems. However, these l...

  10. Energy–exergy analysis and optimisation of a model sugar factory in Turkey

    International Nuclear Information System (INIS)

    Taner, Tolga; Sivrioglu, Mecit

    2015-01-01

    This study is related to the energy and exergy analysis of a model sugar factory in Turkey. In this study, energy efficiency issue in food industries are investigated within a general context to provide energy saving by reducing energy – exergy losses in the sugar production process. The aim of this study is to determine the best energy and exergy efficiency with the mass and energy balances according to design parameters for a sugar factory. Energy savings that can be applied in food industries are examined. Appropriate scenarios are prepared, and optimization results are compared. As a result of thermodynamics calculations made according to the 1st and 2nd Laws of Thermodynamics, energy and exergy efficiencies of a factory were calculated. Factory total energy efficiency and exergy efficiency were found to be 72.2% and 37.4%, respectively, and according to these results, energy quality was found to be 0.64. In conclusion, the current turbine power process energy and exergy efficiencies were 46.4% and 27.7%, respectively, and the optimized turbine power process energy and exergy efficiencies were 48.7% and 31.7%, respectively. This study performs an attitude to the problem of exergy optimization of the turbine power plant. An overall assessment of the energy and exergy efficiency calculations is performed and is focused on how they should be. - Highlights: • The energy and exergy efficiency of a sugar plant depends more on steam than process. • Energy and exergy efficiencies of a factory increase when the turbine power increases, as in a sugar factory. • Statistical analysis demonstrates the precision of data. • Thermoeconomic analysis of the energy and exergy efficiency of the Çumra Sugar Integrated Plant is performed.

  11. Effects of varying composition of biogas on performance and emission characteristics of compression ignition engine using exergy analysis

    International Nuclear Information System (INIS)

    Verma, Saket; Das, L.M.; Kaushik, S.C.

    2017-01-01

    Highlights: • Different compositions of biogas have been studied in dual fuel mode using exergy analysis. • Diesel substitution by biogas decreases with higher CO_2 fractions in biogas. • Exergy efficiency decreases with higher CO_2 fractions in biogas. • With low CO_2 fractions in biogas equitable performance can be obtained in dual fuel mode. • Engine modifications are needed to utilize high CO_2 containing biogas. - Abstract: Growing energy demands and environmental degradation with uncontrolled exploitation of fossil fuels have compelled the world to look for the alternatives. In this context, biogas is a promising candidate, which can easily be utilized in IC engines for vehicular as well as decentralized power generation applications. Primary constituents of raw biogas are methane (CH_4) that defines its heating value, and carbon dioxide (CO_2) that acts like a diluent. This dilution effect reduces the flame speed and heating value of biogas, eventually deteriorating the engine performances. Present article focuses on experimental evaluation and quantification of these variations of the engine performance. Three compositions of biogas: BG93, BG84 and BG75 (containing 93%, 84% and 75% of CH_4 by volume respectively) were studied on a small CI engine in dual fuel mode. Moreover, to evaluate individual process inefficiencies, exergy analysis based on second-law of thermodynamics is implemented. Exergy balances for different compositions of biogas are presented. Biogas dual fuel operation showed 80–90% diesel substitution at lower engine loads. At higher loads, total irreversibility of the engine was increased from 59.56% for diesel operation to 61.44%, 64.18% and 64.64% for BG93, BG84 and BG75 biogas compositions respectively. Furthermore, combustion irreversibility was found to be decreasing with higher CO_2 concentrations in biogas. BG93 showed comparable results to that of diesel operation with 26.9% and 27.4% second-law efficiencies respectively.

  12. Preparation and Characterization of Water-Based Nano-fluids for Nuclear Applications

    International Nuclear Information System (INIS)

    Williams, W.C.; Forrest, E.; Hu, L.W.; Buongiorno, J.

    2006-01-01

    As part of an effort to evaluate water-based nano-fluids for nuclear applications, preparation and characterization has been performed for nano-fluids being considered for MIT's nano-fluid heat transfer experiments. Three methods of generating these nano-fluids are available: creating them from chemical precipitation, purchasing the nano-particles in powder form and mixing them with the base fluid, and direct purchase of prepared nano-fluids. Characterization of nano-fluids includes colloidal stability, size distribution, concentration, and elemental composition. Quality control of the nano-fluids to be used for heat transfer testing is crucial; an exact knowledge of the fluid constituents is essential to uncovering mechanisms responsible for heat transport enhancement. Testing indicates that nano-fluids created by mixing a liquid with nano-particles in powder form are often not stable, although some degree of stabilization is obtainable with pH control and/or surfactant addition. Some commercially available prepared nano-fluids have been found to contain unacceptable levels of impurities and/or include a different weight percent of nano-particles compared to vendor specifications. Tools utilized to characterize and qualify nano-fluids for this study include neutron activation analysis (NAA), inductively-coupled plasma spectroscopy (ICP), transmission electron microscopy (TEM) imaging, thermogravimetric analysis (TGA) and dynamic light scattering (DLS). Preparation procedures and characterization results for selected nano-fluids will be discussed in detail. (authors)

  13. Energy and exergy analyses of a copper-chlorine thermochemical water decomposition pilot plant for hydrogen production

    International Nuclear Information System (INIS)

    Orhan, M.F.; Dincer, I.; Rosen, M.A.

    2008-01-01

    Nuclear-based hydrogen production via thermochemical water decomposition using a copper-chlorine (Cu-Cl) cycle consists of a series of chemical reactions in which water is split into hydrogen and oxygen as the net result. This is accomplished through reactions involving intermediate copper and chlorine compounds, which are recycled. Energy and exergy analyses are reported here of a Cu-Cl pilot plant, including the relevant chemical reactions. The reference environment is taken to be at a temperature of 298.15 K and atmospheric pressure (1 atm). The chemical exergy of a substance, which is the maximum work that can be obtained from it by taking it to chemical equilibrium with the reference environment at constant temperature and pressure, is calculated with property data for the substance and the reference environment, with enthalpy and entropy values calculated using Shomate equations. The reaction heat, exergy destruction and efficiencies in each chemical reaction vary with the reaction temperature and reference-environment temperature. A parametric study with variable reaction and reference-environment temperatures is also presented. (author)

  14. Exergy analysis of the solar still integrated nano composite phase change materials

    International Nuclear Information System (INIS)

    Methre, V.K.; Eswaramoorthy, M.

    2015-01-01

    This paper communicates the exergy analysis of solar still integrated with nano composite phase change materials for design and operating parameters. Al_2O_3 nano materials (50 nm) is dispersed by weight ratio in paraffin wax at melting state and its thermophysical properties are evaluated using developed correlation. Exergy balance equation for basin liner, thermal energy storage, glass cover and saline water is developed and exergy efficiency is analysed. It is found that exergy efficiency is improved by higher weight ratio of Al_2O_3 nano materials with paraffin wax alone. (author)

  15. The influence of Thomson effect in the energy and exergy efficiency of an annular thermoelectric generator

    International Nuclear Information System (INIS)

    Kaushik, S.C.; Manikandan, S.

    2015-01-01

    Highlights: • Exergy analysis in the annular thermoelectric generator (ATEG) system is proposed. • Analytical expressions for the power output, exergy efficiency of an ATEG is derived. • The effects of S r , R L , and θ in P out and exergy efficiency of an ATEG is studied. • The influence of Thomson effect in P out and exergy efficiency of an ATEG is studied. - Abstract: The exoreversible thermodynamic model of an annular thermoelectric generator (ATEG) considering Thomson effect in conjunction with Peltier, Joule and Fourier heat conduction has been investigated using exergy analysis. New expressions for optimum current at the maximum power output and maximum energy, exergy efficiency conditions, and dimensionless irreversibilities in the ATEG are derived. The modified expression for figure of merit of a thermoelectric generator considering the Thomson effect has also been obtained. The results show that the power output, energy and exergy efficiency of the ATEG is lower than the flat plate thermoelectric generator. The effects of annular shape parameter (S r = r 2 /r 1 ), load resistance (R L ), dimensionless temperature ratio (θ = T h /T c ) and the thermal and electrical contact resistances in power output, energy/exergy efficiency of the ATEG have been studied. It has also been proved that because of the influence of Thomson effect, the power output and energy/exergy efficiency of the ATEG is reduced. This study will help in the designing of the actual annular thermoelectric generation systems

  16. Dynamic Exergy Analysis for the Thermal Storage Optimization of the Building Envelope

    Directory of Open Access Journals (Sweden)

    Valentina Bonetti

    2017-01-01

    Full Text Available As a measure of energy “quality”, exergy is meaningful for comparing the potential for thermal storage. Systems containing the same amount of energy could have considerably different capabilities in matching a demand profile, and exergy measures this difference. Exergy stored in the envelope of buildings is central in sustainability because the environment could be an unlimited source of energy if its interaction with the envelope is optimised for maintaining the indoor conditions within comfort ranges. Since the occurring phenomena are highly fluctuating, a dynamic exergy analysis is required; however, dynamic exergy modelling is complex and has not hitherto been implemented in building simulation tools. Simplified energy and exergy assessments are presented for a case study in which thermal storage determines the performance of seven different wall types for utilising nocturnal ventilation as a passive cooling strategy. Hourly temperatures within the walls are obtained with the ESP-r software in free-floating operation and are used to assess the envelope exergy storage capacity. The results for the most suitable wall types were different between the exergy analysis and the more traditional energy performance indicators. The exergy method is an effective technique for selecting the construction type that results in the most favourable free-floating conditions through the analysed passive strategy.

  17. Investigation into the Use of Water Based Brake Fluid for Light Loads

    Directory of Open Access Journals (Sweden)

    W. A. Akpan

    2012-12-01

    Full Text Available This paper addresses the possibility of using water based fluid as a brake fluid for light loads. Characterization of both standard and water based braked fluids formulated was carried out. The properties of the latter were compared with that of a standard commercial brake fluid. The actual test of the formulated brake fluid was carried out with a Nissan Sunny vehicle model 1.5 within the speed range of 20km/hr to 80km/hr at the permanent campus of University of Uyo and the braking efficiency obtained attest to its suitability for light loads.

  18. Nonimaging optics maximizing exergy for hybrid solar system

    Science.gov (United States)

    Winston, Roland; Jiang, Lun; Abdelhamid, Mahmoud; Widyolar, Bennett K.; Ferry, Jonathan; Cygan, David; Abbasi, Hamid; Kozlov, Alexandr; Kirk, Alexander; Elarde, Victor; Osowski, Mark

    2016-09-01

    The project team of University of California at Merced (UC-Merced), Gas Technology Institute (GTI) and MicroLink Devices Inc. (MicroLink) are developing a hybrid solar system using a nonimaging compound parabolic concentrator (CPC) that maximizes the exergy by delivering direct electricity and on-demand heat. The hybrid solar system technology uses secondary optics in a solar receiver to achieve high efficiency at high temperature, collects heat in particles and uses reflective liftoff cooled double junction (2J) InGaP/GaAs solar cells with backside infrared (IR) reflectors on the secondary optical element to raise exergy efficiency. The nonimaging optics provides additional concentration towards the high temperature thermal stream and enables it to operate efficiently at 650 °C while the solar cell is maintained at 40 °C to operate as efficiently as possible.

  19. The exergy underground coal gasification technology for power generation and chemical applications

    Energy Technology Data Exchange (ETDEWEB)

    Blinderman, M.S. [Ergo Exergy Technologies Inc., Montreal, PQ (Canada)

    2006-07-01

    Underground coal gasification (UCG) is a gasification process carried out in non-mined coal seams using injection and production wells drilled from the surface, converting coal in situ into a product gas usable for chemical processes and power generation. The UCG process developed, refined and practised by Ergo Exergy Technologies is called the Exergy UCG Technology or {epsilon}UCG{trademark} technology. This paper describes the technology and its applications. The {epsilon}UCG technology is being applied in numerous power generation and chemical projects worldwide, some of which are described. These include power projects in South Africa, India, Pakistan and Canada, as well as chemical projects in Australia and Canada. A number of {epsilon}UCG{trademark} based industrial projects are now at a feasibility usage in India, New Zealand, USA and Europe. An {epsilon}UCG{trademark} IGCC power plant will generate electricity at a much lower cost than existing fossil fuel power plants. CO{sub 2} emissions of the plant can be reduced to a level 55% less than those of a supercritical coal-fired plant and 25% less than the emissions of NG CC. 10 refs., 8 figs.

  20. A critical review on energy, exergy, exergoeconomic and economic (4-E analysis of thermal power plants

    Directory of Open Access Journals (Sweden)

    Ravinder Kumar

    2017-02-01

    Full Text Available The growing energy supply, demand has created an interest towards the plant equipment efficiency and the optimization of existing thermal power plants. Also, a thermal power plant dependency on fossil fuel makes it a little bit difficult, because of environmental impacts has been always taken into consideration. At present, most of the power plants are going to be designed by the energetic performance criterion which is based on the first law of thermodynamics. Sometimes, the system energy balance is not sufficient for the possible finding of the system imperfections. Energy losses taking place in a system can be easily determined by using exergy analysis. Hence, it is a powerful tool for the measurement of energy quality, thereby helps to make complex thermodynamic systems more efficient. Nowadays, economic optimization of plant is also a big problem for researchers because of the complex nature. At a viewpoint of this, a comprehensive literature review over the years of energy, exergy, exergoeconomic and economic (4-E analysis and their applications in thermal power plants stimulated by coal, gas, combined cycle and cogeneration system have been done thoroughly. This paper is addressed to those researchers who are doing their research work on 4-E analysis in various thermal power plants. If anyone extracts an idea for the development of the concept of 4-E analysis using this article, we will achieve our goal. This review also indicates the scope of future research in thermal power plants.

  1. Energy and Exergy Analysis of Cogeration System with Biogas Engines

    OpenAIRE

    Doseva, Nadezhda; Chakyrova, Daniela

    2015-01-01

    In this paper, an existing cogeneration system driven by biogas internal combustion engines (ICE) is a subject of an investigation by energy and exergy analyses. The system is installed in the Varna Wastewater Treatment Plant (Varna WWTP), Bulgaria and its purpose is to utilize the methane produced as a byproduct of the solids stabilization process at Varna WWTP. Otherwise, the produced methane would pollute the environment. The presented paperhas been organised in the following way: first, i...

  2. Exergy analysis of an experimental heat transformer for water purification

    International Nuclear Information System (INIS)

    Rivera, W.; Huicochea, A.; Martinez, H.; Siqueiros, J.; Juarez, D.; Cadenas, E.

    2011-01-01

    First and second law of thermodynamics have been used to analyze the performance of an experimental heat transformer used for water purification. The pure water is produced in the auxiliary condenser delivering an amount of heat, which is recycled into the heat transformer increasing the heat source temperatures and also the internal, external and exergy coefficients of performance. The theoretical and experimental study was divided into two parts. In the first part, a second law analysis was carried out to the experimental system showing that the absorber and the condenser are the components with the highest irreversibilities. In the second part, with the results obtained from the second law analysis, new test runs were carried out at similar conditions than the former but varying only one selected temperature at the time. Comparing the COP (coefficient of performance) between the old and new test runs, it was shown that higher internal, external and exergy coefficients of performance were obtained in all the new test runs. Also it was shown that the ECOP (exergy coefficient of performance) increases with an increment of the amount of the purified water produced and with the decrease of the flow ratio. -- Research highlights: → By the first time an experimental results of a heat transformer for water purification with heat recycling has been presented. → An exergy analysis has been carried out in order to identify the irreversibilities in the main components of the system. → With the results obtained of the second law analysis new experimental test runs were carried out minimizing the system irreversibilities and furthermore increasing the system efficiency.

  3. The concept 'environment' in exergy analysis Some special cases

    International Nuclear Information System (INIS)

    Serova, E.N.; Brodianski, V.M.

    2004-01-01

    The concept 'environment' is of considerable importance in present-day engineering thermodynamics. Introduction of this concept in operation brings not only simplification of the methods of solving classical thermodynamic problems, but also gives the exergy method which forms the major new part of thermodynamics, including some parts of biology, economics and other fields of science. But practice shows that it is necessary to define the concept 'environment' more precisely in some cases

  4. The exergy fields in transport processes: Their calculation and use

    Energy Technology Data Exchange (ETDEWEB)

    Lior, N.; Sarmiento-Darkin, W.; Al-Sharqawi, H.S. [University of Penn, Philadelphia, PA (United States). Dept. of Mechanical Engineering & Applied Mechanics

    2006-04-15

    This paper is a brief review of the method for analyzing the space and time dependent exergy and irreversibility fields in processes. It presents the basic equations, the method for their use, major literature sources, and three examples from the authors' work: flow desiccation, combustion of oil droplets, and combustion of pulverized coal. Conclusions from this Second Law analysis are used to attempt process improvement suggestions.

  5. Optimization-based Fluid Simulation on Unstructured Meshes

    DEFF Research Database (Denmark)

    Misztal, Marek Krzysztof; Bridson, Robert; Erleben, Kenny

    2010-01-01

    for solving the fluid dynamics equations as well as direct access to the interface geometry data, making in- clusion of a new surface energy term feasible. Furthermore, using an unstructured mesh makes it straightforward to handle curved solid boundaries and gives us a possibility to explore several fluid...

  6. ANALYSIS OF EXERGY PARAMETERS OF BIOGAS POWER PLANT

    Directory of Open Access Journals (Sweden)

    Denysova A.E.

    2014-08-01

    Full Text Available The techniques of an exergy analysis concerning various circuits of biogas units, which allows replacing traditional energy resources and improving environmental conditions, has been presented. The heat schemes of biogas units were proposed, and analysis of their effectiveness was made. The comparison of different cycle parameters of various biogas units (i.e. a combustion turbine unit, a combined cycle gas turbine unit with gas discharges into the boiler and a combined cycle gas turbine with a high-temperature vapor generator and a reheating stage was made, and the comparison of their exergy characteristics was carried out. The results of exergy analysis had demonstrated that the cycle of biogas CCGT (combined cycle gas turbine with a reheating stage and using a high-pressure steam generator is the most effective, that can be explained by the fact that the thermal energy proportions of combustion products, accounting for the steam cycle and the gas cycle are approximately equal, comparing to conventional combined cycle gas turbine units.

  7. Energy-, exergy- and emergy analysis of biomass production

    Energy Technology Data Exchange (ETDEWEB)

    Hovelius, K.

    1997-11-01

    In this report, results from analyzing salix-, winter wheat-, and winter rape cultivations from energy, exergy, and EMERGY perspectives are presented. The exchange in terms of energy for this Salix cultivation is 28 times , but if instead an exergy analysis is done the exchange for exactly the same process is 36 times. The energy analysis gives an energy exchange of 8.1 for winter wheat cultivation, and 5.7 for winter rape cultivation. Corresponding exchanges for the exergy analysis are 9.3 for winter wheat and 6.6 for winter rape. The EMERGY analysis gives a transformity for salix of 1.04E+11 sej/kg DM, for winter wheat 3.85E+11 sej/kg DM, and for winter rape 1.03E+12 sej/kg DM. Thus, the EMERGY need is bigger for rape cultivation than for winter wheat and salix cultivations. The NEYR is the ratio between the EMERGY yield and the EMERGY invested from society (economy, services and other resources), and it is 1.10 for this salix cultivation, and 0.66 for both the winter wheat and the winter rape cultivations. The EIR is the ratio between the EMERGY invested from society and the EMERGY invested from the environment, and it is 2.23 for this salix cultivation, 11.5 for the winter wheat cultivation , and 11.8 for the winter rape cultivation. 26 refs, 11 figs, 25 tabs

  8. Physically-Based Rendering of Particle-Based Fluids with Light Transport Effects

    Science.gov (United States)

    Beddiaf, Ali; Babahenini, Mohamed Chaouki

    2018-03-01

    Recent interactive rendering approaches aim to efficiently produce images. However, time constraints deeply affect their output accuracy and realism (many light phenomena are poorly or not supported at all). To remedy this issue, in this paper, we propose a physically-based fluid rendering approach. First, while state-of-the-art methods focus on isosurface rendering with only two refractions, our proposal (1) considers the fluid as a heterogeneous participating medium with refractive boundaries, and (2) supports both multiple refractions and scattering. Second, the proposed solution is fully particle-based in the sense that no particles transformation into a grid is required. This interesting feature makes it able to handle many particle types (water, bubble, foam, and sand). On top of that, a medium with different fluids (color, phase function, etc.) can also be rendered.

  9. Avoidable and unavoidable exergy destructions of a fluidized bed coal combustor and a heat recovery steam generator

    International Nuclear Information System (INIS)

    Callak, Meliha; Balkan, Firuz; Hepbasli, Arif

    2015-01-01

    Highlights: • Performing advanced exergy analysis of a fluidized-bed combustion for the first time. • Comparing conventional and modified exergy efficiencies of the subsystems. • Deducting inefficiencies of the system components for possible improvements. - Abstract: Advanced exergy analysis was performed using the actual operational data taken from a fluidized bed coal combustor (FBCC) and a heat recovery steam generator (HRSG) in a textile plant located at Torbalı, Izmir. First, the conventional exergy analysis of the units was carried out. The exergetic efficiencies of the units were found to be 44.2% and 46.2%, respectively. Advanced exergy analysis was then performed by splitting the exergy destructions of the units into avoidable and unavoidable parts. The avoidable exergy destruction rates of the FBCC and the HRSG were determined to be 2999 kW and 760 kW according to the measurements. Correspondingly, the exergy efficiencies were modified to 53.1% and 48.1%, respectively

  10. Improvement potential of a real geothermal power plant using advanced exergy analysis

    International Nuclear Information System (INIS)

    Gökgedik, Harun; Yürüsoy, Muhammet; Keçebaş, Ali

    2016-01-01

    The main purpose of this paper is to quantitatively evaluate thermodynamic performance of a geothermal power plant (GPP) from potential for improvement point of view. Thus, sources of inefficiency and irreversibilities can be determined through exergy analysis. The advanced exergy analysis is more appropriate to determine real potential for thermodynamic improvements of the system by splitting exergy destruction into unavoidable and avoidable portions. The performance critical components and the potential for exergy efficiency improvement of a GPP were determined by means of the advanced exergy analysis. This plant is the Bereket GPP in Denizli/Turkey as a current operating system. The results show that the avoidable portion of exergy destruction in all components except for the turbines is higher than the unavoidable value. Therefore, much can be made to lessen the irreversibilities for components of the Bereket GPP. The total exergy efficiency of the system is found to be 9.60%. Its efficiency can be increased up to 15.40% by making improvements in the overall components. Although the heat exchangers had lower exergy and modified exergy efficiencies, their exergy improvement potentials were high. Finally, in the plant, the old technology is believed to be one of the main reasons for low efficiencies. - Highlights: • Evaluation of potential for improvement of a GPP using advanced exergy analysis. • Efficiency can be increased up to 15.40% by making improvements in the components. • Heat exchangers are the highest avoidable values, making them the least efficient components in plant. • The main reasons for low efficiencies are believed to be the old technology.

  11. Drivers of choice for fluid milk versus plant-based alternatives: What are consumer perceptions of fluid milk?

    Science.gov (United States)

    McCarthy, K S; Parker, M; Ameerally, A; Drake, S L; Drake, M A

    2017-08-01

    Fluid milk consumption has declined for decades while consumption of nondairy alternatives has increased. A better understanding of why consumers purchase fluid milk or nondairy alternatives is needed to assist increased sales of milk or maintain sales without further decline. The objective of this study was to determine the extrinsic attributes that drive purchase within each product category. The second objective was to determine the personal values behind the purchase of each beverage type to give further understanding why particular attributes are important. An online conjoint survey was launched with 702 dairy consumers, 172 nondairy consumers, and 125 consumers of both beverages. Individual means-end chain interviews were conducted with fluid milk consumers (n = 75), plant-based alternative consumers (n = 68), and consumers of both beverages (n = 78). Fat content was the most important attribute for dairy milk followed by package size and label claims. Consumers of fluid milk preferred 1 or 2% fat content, gallon, or half-gallon packaging, conventionally pasteurized store-brand milk. Sugar level was the most important attribute for plant-based beverages, followed by plant source and package size. Almond milk was the most desirable plant source, and half-gallon packaging was the most preferred packaging. Means-end chain interviews results suggested that maintaining a balanced diet and healthy lifestyle was important to all consumer groups. Lactose free was an important attribute for plant-based alternative consumers and consumers of both dairy and nondairy. A distinguishing characteristic of those who only drank nondairy plant-based alternatives was that plant-based beverages contributed to a goal to consume less animal products, beliefs about animal mistreatment, and perceived lesser effect on the environment than fluid milk. Unique to fluid milk consumers was that fluid milk was perceived as a staple food item. These results suggest that the dairy industry

  12. Crystallization from a milk-based revised simulated body fluid

    International Nuclear Information System (INIS)

    Dorozhkin, Sergey V; Dorozhkina, Elena I

    2007-01-01

    A milk-based revised simulated body fluid (milk-rSBF) was prepared by a conventional route but instead of deionized water, all necessary chemicals were dissolved in whole cow's milk (3.2% fat). In order to accelerate crystallization and increase the amount of precipitates, the influence of milk was studied from condensed solutions equal to four times the ionic concentrations of rSBF (4rSBF). The experiments were performed under physiological conditions (solution pH = 7.35-7.40, temperature 37.0 ± 0.2 deg. C, duration 7 days) in a constant-composition double-diffusion device, which provided a slow crystallization under strictly controlled conditions. Similar experiments with 4rSBF but dissolved in deionized water were used as a control. An extra set of experiments with 4rSBF dissolved in deionized water but with an addition of 40 g l -1 bovine serum albumin (BSA) was used as another control. The influence of milk appeared to be similar to that of dissolved BSA: some components of milk (presumably albumins and proteins) were found to co-precipitate with calcium phosphates, which had a strong negative influence on both the crystallinity and the crystal sizes of the precipitates. In addition, both milk and BSA strongly inhibited crystallization of calcium phosphates: the precipitates turned out to contain a minor amount of calcium phosphates and a substantial amount of organic phase

  13. Graphene nanoplatelets as high-performance filtration control material in water-based drilling fluids

    Science.gov (United States)

    Ridha, Syahrir; Ibrahim, Arif; Shahari, Radzi; Fonna, Syarizal

    2018-05-01

    The main objective of this work is to evaluate the effectiveness of graphene nanoplatelets (GNP) as filtration control materials in water based drilling fluids. Three (3) general samples of water based drilling fluids were prepared including basic potassium chloride (KCl) drilling fluids, nanosilica (NS) drilling fluids and GNP drilling fluids. Several concentrations of NS and GNP were dispersed in controlled formulations of water based drilling fluids. Standard API filtration tests were carried out for comparison purposes as well as High Temperature High Pressure (HTHP) filtration tests at 150 °F (∼66 °C), 250 °F (∼121 °C) and 350 °F (∼177 °C) at a fixed 500 (∼3.45MPa) psi to study the filtration trend as a function of temperature. Mud cake samples from several tests were selectively chosen and analyzed under Field Emission Scanning Electron Microscope (FESEM) for its morphology. Results from this work show that nanoparticle concentrations play a factor in filtration ability of colloid materials in water based drilling fluids when studied at elevated temperature. Low temperature filtration, however, shows only small differences in volume in all the drilling fluid samples. 0.1 ppb concentrations of GNP reduced the fluid loss of 350 °F by 4.6 mL as compared to the similar concentration of NS drilling fluids.

  14. Assessment of the energy and exergy efficiencies of farm to fork grain cultivation and bread making processes in Turkey and Germany

    International Nuclear Information System (INIS)

    Degerli, Bahar; Nazir, Serap; Sorgüven, Esra; Hitzmann, Bernd; Özilgen, Mustafa

    2015-01-01

    Energy and exergy efficiencies of the wheat and rye bread and hamburger bun making processes are assessed based on data from Turkey and Germany. Amount of the land required to produce the same amount of wheat in Turkey is 3.34 times of that required in Germany; this ratio is 2.30 for the rye grain. These results show that the efficiency of the conversion of the solar energy into the grain mass is low in Turkey. CDP (Cumulative degree of perfection) for the wheat and the rye grain production is 3.73 and 4.96 in Turkey, and 11.26 and 10.46 in Germany. Specific energy utilization for rye bread production is almost the same in Turkey and Germany; but it is 12% higher in Turkey for wheat bread and hamburger bun making. Hamburger bun production requires the maximum energy utilization due to the higher weight loss in baking. The rye bread production process requires the minimum energy utilization due to the lower energy input in the agriculture and higher efficiency in the flour production. The maximum exergy destructions occur during the milling and the baking steps. - Highlights: • Agriculture determines the energy and exergy efficiency of bread making. • Conversion efficiency of the solar energy into grain mass is lower in Turkey. • The smallest energy and exergy is needed for the rye bread making. • The largest energy and exergy is needed for the hamburger bun making. • Energy efficiency per mass of bread production is 12% higher in Germany.

  15. Exergy analysis of a gas turbine power plant | Oko | Journal of ...

    African Journals Online (AJOL)

    Exergy analysis of a 100MW gas turbine power plant that works on the. Brayton cycle is presented. The average increase in the thermodynamic degradation of the plant over the period of six (6) years at three different levels of load was assessed. The exergy analysis of the plant was done on two sets of data: one from the ...

  16. A relation between calculated human body exergy consumption rate and subjectively assessed thermal sensation

    Energy Technology Data Exchange (ETDEWEB)

    Simone, Angela; Kolarik, Jakub; Olesen, Bjarne W. [ICIEE/BYG, Technical University of Denmark (Denmark); Iwamatsu, Toshiya [Faculty of Urban Environmental Science, Tokyo Metropolitan University (Japan); Asada, Hideo [Architech Consulting Co., Tokyo (Japan); Dovjak, Mateja [Faculty of Civil and Geodetic Engineering, University of Ljubljana (Slovenia); Schellen, Lisje [Eindhoven University of Technology, Faculty of Architecture Building and Planning (Netherlands); Shukuya, Masanori [Laboratory of Building Environment, Tokyo City University, Yokohama (Japan)

    2011-01-15

    Application of the exergy concept to research on the built environment is a relatively new approach. It helps to optimize climate conditioning systems so that they meet the requirements of sustainable building design. As the building should provide a healthy and comfortable environment for its occupants, it is reasonable to consider both the exergy flows in building and those within the human body. Until now, no data have been available on the relation between human-body exergy consumption rates and subjectively assessed thermal sensation. The objective of the present work was to relate thermal sensation data, from earlier thermal comfort studies, to calculated human-body exergy consumption rates. The results show that the minimum human body exergy consumption rate is associated with thermal sensation votes close to thermal neutrality, tending to the slightly cool side of thermal sensation. Generally, the relationship between air temperature and the exergy consumption rate, as a first approximation, shows an increasing trend. Taking account of both convective and radiative heat exchange between the human body and the surrounding environment by using the calculated operative temperature, exergy consumption rates increase as the operative temperature increases above 24 C or decreases below 22 C. With the data available so far, a second-order polynomial relationship between thermal sensation and the exergy consumption rate was established. (author)

  17. An application of energy and exergy analysis in agricultural sector of Malaysia

    International Nuclear Information System (INIS)

    Ahamed, J.U.; Saidur, R.; Masjuki, H.H.; Mekhilef, S.; Ali, M.B.; Furqon, M.H.

    2011-01-01

    Thermodynamic losses usually take place in machineries used for agricultural activities. Therefore, it is important to identify and quantify the losses in order to devise strategies or policies to reduce them. An exergy analysis is a tool that can identify the losses occurred in any sector. In this study, an analysis has been carried out to estimate energy and exergy consumption of the agricultural sector in Malaysia. Energy and exergy efficiencies have been determined for the devices used in the agricultural sector of Malaysia, where petrol, diesel and fuel oil are used to run the machineries. Energy and exergy flow diagrams for the overall efficiencies of Malaysian agricultural sector are presented as well. The average overall energy and exergy efficiencies of this sector were found to be 22% and 20.728%, respectively, within the period from 1991 to 2009. These figures were found to be lower than those of Norway but higher than Turkey. - Highlights: ► Highest exergy efficiency was found about 20.7% for the year 2007. ► The exergy efficiency of the agro-sector in Malaysia was lower than that of energy efficiency. ► It was also found that this sector of Malaysia is less efficient than Saudi Arabia and Norway. ► Energy and exergy losses were identified through this analysis. ► Part of the losses can be reduced using appropriate technology, management and policy.

  18. Exergy analysis of a circulating fluidized bed boiler cogeneration power plant

    International Nuclear Information System (INIS)

    Gürtürk, Mert; Oztop, Hakan F.

    2016-01-01

    Highlights: • Analysis of energy and exergy for a cogeneration power plant have been performed. • This plant has circulating fluidized bed boiler. • Energy and exergy efficiencies of the boiler are obtained as 84.65% and 29.43%, respectively. • Exergy efficiency of the plant was calculated as 20%. - Abstract: In this study, energy and exergy analysis of a cogeneration power plant have been performed. The steam which is produced by the cogeneration power plant is used for salt production and most important part of the cogeneration power plant is the circulation fluidized bed boiler. Energy and exergy efficiency of the circulation fluidized bed boiler were found as 84.65% and 29.43%, respectively. Exergy destruction of the circulation fluidized bed boiler was calculated as 21789.39 kW and 85.89% of exergy destruction in the plant. The automation system of the cogeneration power plant is insufficient. Exergy efficiency of the plant was calculated as 20%. Also, some design parameters increasing energy losses were determined.

  19. Energy and advanced exergy analysis of an existing hydrocarbon recovery process

    International Nuclear Information System (INIS)

    Mehrpooya, Mehdi; Lazemzade, Roozbeh; Sadaghiani, Mirhadi S.; Parishani, Hossein

    2016-01-01

    Highlights: • Advanced exergoeconomic analysis is performed for propane refrigerant system. • Avoidable/unavoidable & endogenous/exogenous irreversibilities were calculated. • Advanced exergetic analysis identifies the potentials for improving the system. - Abstract: An advanced exergy analysis of the Ethane recovery plant in the South Pars gas field is presented. An industrial refrigeration cycle with propane refrigerant is investigated by the exergy analysis method. The equations of exergy destruction and exergetic efficiency for the main cycle units such as evaporators, condensers, compressors, and expansion valves are developed. Exergetic efficiency of the refrigeration cycle is determined to be 33.9% indicating a high potential for improvements. The simulation results reveal that the exergy loss and exergetic efficiencies of the air cooler and expansion sections respectively are the lowest among the compartments of the cycle. The coefficient of performance (COP) is obtained as 2.05. Four parts of irreversibility (avoidable/unavoidable) and (endogenous/exogenous) are calculated for the units with highest inefficiencies. The advanced exergy analysis reveals that the exergy destruction has two major contributors: (1) 59.61% of the exergy is lost in the unavoidable form in all units and (2) compressors contribute to 25.47% of the exergy destruction. So there is a high potential for improvement for these units, since 63.38% of this portion is avoidable.

  20. Energy and exergy use in public and private sector of Saudi Arabia

    Energy Technology Data Exchange (ETDEWEB)

    Dincer, I. E-mail: idincer@kfupm.edu.sa; Hussain, M.M.; Al-Zaharnah, I

    2004-09-01

    In this paper, we deal with the analysis of energy and exergy utilization in the public and private sector of Saudi Arabia by considering the energy and exergy flows for the years between 1990 and 2001. Energy and exergy analyses for the public and private sector are undertaken to study the energy and exergy efficiencies. These sectoral efficiencies are then compared, and energy and exergy flow diagrams for the public and private sector over the years are presented, respectively. Energy and exergy efficiencies of the public and private sector are compared for its six sub-sectors, namely commercial, governmental, streets, Mosques, hospitals and charity associations, particularly illustrated for the year 2000. Hospital sub-sector appears to be the most energy efficient sector and government sub-sector the most exergy efficient one. The results presented here provide insights into the sectoral energy use that may assist energy policy makers for the country. It is believed that the present techniques are useful for analyzing sectoral energy and exergy utilization, and that they provide Saudi Arabia with energy savings through energy efficiency and/or energy conservation measures. It is also be helpful to establish standards to facilitate application in industry and in other planning processes such as energy planning.

  1. energy and exergy evaluation of a 220mw thermal power plant

    African Journals Online (AJOL)

    HOD

    The outcomes of this work provide the exergy consumption and distribution profiles of the thermal power plant ... power plant with post-combustion CO2 capture. The once-through boiler exhibited the highest exergy destruction of all the plants ...

  2. Energy and exergy use in public and private sector of Saudi Arabia

    International Nuclear Information System (INIS)

    Dincer, I.; Hussain, M.M.; Al-Zaharnah, I.

    2004-01-01

    In this paper, we deal with the analysis of energy and exergy utilization in the public and private sector of Saudi Arabia by considering the energy and exergy flows for the years between 1990 and 2001. Energy and exergy analyses for the public and private sector are undertaken to study the energy and exergy efficiencies. These sectoral efficiencies are then compared, and energy and exergy flow diagrams for the public and private sector over the years are presented, respectively. Energy and exergy efficiencies of the public and private sector are compared for its six sub-sectors, namely commercial, governmental, streets, Mosques, hospitals and charity associations, particularly illustrated for the year 2000. Hospital sub-sector appears to be the most energy efficient sector and government sub-sector the most exergy efficient one. The results presented here provide insights into the sectoral energy use that may assist energy policy makers for the country. It is believed that the present techniques are useful for analyzing sectoral energy and exergy utilization, and that they provide Saudi Arabia with energy savings through energy efficiency and/or energy conservation measures. It is also be helpful to establish standards to facilitate application in industry and in other planning processes such as energy planning

  3. An application of energy and exergy analysis in residential sector of Malaysia

    International Nuclear Information System (INIS)

    Saidur, R.; Masjuki, H.H.; Jamaluddin, M.Y.

    2007-01-01

    In this paper, the useful concept of energy and exergy utilization is defined, analyzed and applied to the residential sector of Malaysia by taking into account the energy and exergy flows for a period of 8 years from the year 1997 to 2004. The energy and exergy efficiencies are determined for the devices used in this sector and found to be 70% and 28%, respectively. Energy and exergy flow diagrams for the overall efficiencies of Malaysian residential sector are also illustrated in this paper. It is found that the current methodology applied in Saudi Arabia is suitable to analyze energy and exergy use in Malaysian residential sector. It has been found that the exergy efficiency of the Malaysian residential sector appears to be much lower than its corresponding energy efficiency. It has been observed that about 21% of total exergy losses are caused by refrigerator-freezer and 12% of total loss is caused by air conditioner. Washing machine, fan and rice cooker contribute about 11%, 10% and 8% of total exergy losses, respectively

  4. Energy, Exergy and Performance Analysis of Small-Scale Organic Rankine Cycle Systems for Electrical Power Generation Applicable in Rural Areas of Developing Countries

    Directory of Open Access Journals (Sweden)

    Suresh Baral

    2015-01-01

    Full Text Available This paper introduces the concept of installing a small-scale organic Rankine cycle system for the generation of electricity in remote areas of developing countries. The Organic Rankine Cycle Systems (ORC system uses a commercial magnetically-coupled scroll expander, plate type heat exchangers and plunger type working fluid feed pump. The heat source for the ORC system can be solar energy. A series of laboratory tests were conducted to confirm the cycle efficiency and expander power output of the system. Using the actual system data, the exergy destruction on the system components and exergy efficiency were assessed. Furthermore, the results of the variations of system energy and exergy efficiencies with different operating parameters, such as the evaporating and condensing pressures, degree of superheating, dead state temperature, expander inlet temperature and pressure ratio were illustrated. The system exhibited acceptable operational characteristics with good performance under a wide range of conditions. A heat source temperature of 121 °C is expected to deliver a power output of approximately 1.4 kW. In addition, the system cost analysis and financing mechanisms for the installation of the ORC system were discussed.

  5. Energy and exergy analysis at the utility and commercial sectors of Malaysia

    International Nuclear Information System (INIS)

    Saidur, R.; Sattar, M.A.; Masjuki, H.H.; Abdessalam, H.; Shahruan, B.S.

    2007-01-01

    In this paper, sectoral energy and exergy analysis model is applied to the utility and commercial sectors of Malaysia by considering the energy and exergy flows from 1990 to 2003. The energy and exergy efficiencies are determined for the sub-sectors and devices used in these two sectors. It has been found the hydroelectric power plant sub-sector is more energy and exergy efficient compared to the thermal power plant sub-sector. The energy and exergy efficiencies of utility and commercial sectors of Malaysia are compared with a few other countries around the world as well. The utility and commercial sectors of Malaysia are found to be more efficient than that of Thailand, Brunei, China, and Vietnam in 1999

  6. Exergy losses of resource recovery from a waste-to-energy plant

    DEFF Research Database (Denmark)

    Vyzinkarova, Dana; Laner, D.; Astrup, Thomas Fruergaard

    2013-01-01

    Metal resources recovered from waste incineration bottom ash (BA) are of lower quality as compared to primary resources, but to date no framework for expressing the quality losses exists. Exergy is a concept that may have the potential to evaluate the resource quality in waste management....... In this study, focusing on recovery from waste-to-energy plants with basic and advanced BA treatment, the goal is to give an indication about quality of selected recovered resources (Fe, Al, and Cu) by means of exergy analysis. Metal flows are modeled through both incineration scenarios, and then chemical....... The results indicate that exergy losses due to mixing are insignificant as compared to chemical exergies of metals in all flows. Total exergy losses for Fe, Al, and Cu recovery in the two WtE systems range from 38% to 90%....

  7. WEXA: exergy analysis for increasing the efficiency of air/water heat pumps - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Gasser, L.; Wellig, B.; Hilfiker, K.

    2008-04-15

    This comprehensive final report for the Swiss Federal Office of Energy (SFOE) presents the results of a study at the made by the Engineering and Architecture department at the Lucerne University of Applied Sciences and Arts. The subject of the WEXA study (Waermepumpen-Exergie-Analyse - heat pump exergy analysis) is the analysis of the operation of air/water heat-pumps using exergy analysis methods. The basic thermodynamics of heating systems using heat-pumps is discussed. The exergy analyses and exergy balances for the various components and processes of an air/water heat-pump are presented and discussed. Comparisons are presented for heat-pumps with on/off and continuous control systems for their compressors and fans. The paper is concluded with a collection of appendices on the subject.

  8. Numerical Analysis of Exergy for Air-Conditioning Influenced by Ambient Temperature

    Directory of Open Access Journals (Sweden)

    Jing-Nang Lee

    2014-07-01

    Full Text Available The article presents numerical analysis of exergy for air-conditioning influenced by ambient temperature. The model of numerical simulation uses an integrated air conditioning system exposed in varied ambient temperature to observe change of the four main devices, the compressor, the condenser, the capillary, and the evaporator in correspondence to ambient temperature. The analysis devices of the four devices’s exergy influenced by the varied ambient temperature and found that the capillary has unusual increasing exergy loss vs. increasing ambient temperature in comparison to the other devices. The result shows that reducing exergy loss of the capillary influenced by the ambient temperature is the key for improving working efficiency of an air-conditioning system when influence of the ambient temperature is considered. The higher ambient temperature causes the larger pressure drop of capillary and more exergy loss.

  9. Energy and exergy analysis of a two pass photovoltaic –thermal (PV/T) air heater

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, M.; Jayaraj, S. [Department of Mechanical Engineering, National Institute of Technology, Calicut-673601 (India)

    2013-07-01

    A double pass hybrid solar air (PV/T) heater with slats is designed and fabricated to study elaborately its thermal and electrical performance corresponding to the warm and humid environment. Air as a heat removing fluid is made to flow through upper and lower channels of the collector. The collector is designed in such way that the absorber plate is partially covered by solar cells. Thin metallic strips (called slats) are attached longitudinally at the bottom side of the absorber plate to improve the overall system performance (by increasing the cooling rate of the absorber plate). Thermal and electrical performances of the whole system at different cooling rates are presented. The exergy analysis of double pass hybrid solar air (PV/T) heater with slats has also been carried out. The instantaneous overall energy and overall exergy efficiency of the double pass hybrid (PV/T) solar air heater varies between 29 – 37 percent and 14-17 percent respectively. These obtained values are comparable with that of published results.

  10. Sensitivity of energy and exergy performances of heating and cooling systems to auxiliary components

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

    2017-01-01

    . Different forms of energy (electricity and heat) are used in heating and cooling systems, and therefore, a holistic approach to system design and analysis is needed. In particular, distribution systems use electricity as a direct input to pumps and fans, and to other components. Therefore, exergy concept......Heating and cooling systems in buildings consist of three main subsystems: heating/cooling plant, distribution system, and indoor terminal unit. The choice of indoor terminal unit determines the characteristics of the distribution system and the heating and cooling plants that can be used...... should be used in design and analysis of the whole heating and cooling systems, in addition to the energy analysis. In this study, water-based (floor heating and cooling, and radiator heating) and air-based (air heating and cooling) heating and cooling systems were compared in terms of their energy use...

  11. Mathematical modeling of the dynamic stability of fluid conveying pipe based on integral equation formulations

    International Nuclear Information System (INIS)

    Elfelsoufi, Z.; Azrar, L.

    2016-01-01

    In this paper, a mathematical modeling of flutter and divergence analyses of fluid conveying pipes based on integral equation formulations is presented. Dynamic stability problems related to fluid pressure, velocity, tension, topography slope and viscoelastic supports and foundations are formulated. A methodological approach is presented and the required matrices, associated to the influencing fluid and pipe parameters, are explicitly given. Internal discretizations are used allowing to investigate the deformation, the bending moment, slope and shear force at internal points. Velocity–frequency, pressure-frequency and tension-frequency curves are analyzed for various fluid parameters and internal elastic supports. Critical values of divergence and flutter behaviors with respect to various fluid parameters are investigated. This model is general and allows the study of dynamic stability of tubes crossed by stationary and instationary fluid on various types of supports. Accurate predictions can be obtained and are of particular interest for a better performance and for an optimal safety of piping system installations. - Highlights: • Modeling the flutter and divergence of fluid conveying pipes based on RBF. • Dynamic analysis of a fluid conveying pipe with generalized boundary conditions. • Considered parameters fluid are the pressure, tension, slopes topography, velocity. • Internal support increase the critical velocity value. • This methodologies determine the fluid parameters effects.

  12. Current and future energy and exergy efficiencies in the Iran’s transportation sector

    International Nuclear Information System (INIS)

    Zarifi, F.; Mahlia, T.M.I.; Motasemi, F.; Shekarchian, M.; Moghavvemi, M.

    2013-01-01

    Highlights: • The overall energy and exergy efficiencies of the sector were calculated. • The overall efficiencies were compared to other countries. • The overall energy and exergy efficiencies have been predicted by scenario approach. • A summary of recommendations to improve the sector is provided. - Abstract: Transportation is the second largest energy consumer sector in Iran which accounts for 24% of total energy consumption in 2009. This large percentage (almost a quarter) of energy consumption necessitates the determination of energy and exergy flows and their respective losses, which will enable the reduction of both energy growth and its consequent environmental impacts in the near future. This paper attempts to analyze and investigate the energy and exergy utilization of the transportation sector in Iran for the period of 1998–2009. Additionally, the total energy consumption in each subsector and the overall energy and exergy efficiencies are predicted via scenario approach. A comparison of the overall energy and exergy efficiencies of Iran with six other countries is also presented. The results show that the overall energy and exergy efficiencies of transportation sector in Iran is higher than China and Norway, while it is lower than Saudi Arabia, Jordan, Turkey, and Malaysia for the year 2000. Road appears to be the most efficient subsector. The overall energy efficiency is determined to be in the range of 22.02% in 1998, to 21.49% in 2009, while the overall exergy efficiency is determine to be in the range of 21.47% in 1998, to 21.19% in 2009. The energy consumption in each subsector is predicted from 2010 to 2035. It was discovered that the overall energy and exergy efficiencies possesses an upward trend during this time period. Finally, some recommendations vis-à-vis the improvement of the energy and exergy efficiencies in Iranian transportation sector in the future was provided and duly discussed

  13. Performance analysis of an integrated gas-, steam- and organic fluid-cycle thermal power plant

    International Nuclear Information System (INIS)

    Oko, C.O.C.; Njoku, I.H.

    2017-01-01

    This paper presents the performance analysis of an existing combined cycle power plant augmented with a waste heat fired organic Rankine cycle power plant for extra power generation. This was achieved by performing energy and exergy analysis of the integrated gas-, steam- and organic fluid-cycle thermal power plant (IPP). Heat source for the subcritical organic Rankine cycle (ORC) was the exhaust flue gases from the heat recovery steam generators of a 650 MW natural gas fired combined cycle power plant. The results showed that extra 12.4 MW of electricity was generated from the attached ORC unit using HFE7100 as working fluid. To select ORC working fluid, ten isentropic fluids were screened and HFE7100 produced the highest net power output and cycle efficiency. Exergy and energy efficiencies of the IPP improved by 1.95% and 1.93%, respectively. The rate of exergy destruction in the existing combined cycle plant was highest in the combustion chamber, 59%, whereas in the ORC, the highest rate of exergy destruction occurred in the evaporator, 62%. Simulations showed exergy efficiency of the IPP decreased with increasing ambient temperature. Exit stack flue gas temperature reduced from 126 °C in the combined cycle power plant to 100 °C in the integrated power plant. - Highlights: • Combined cycle plant retrofitted with ORC produced extra 12.4 MW electric power. • ORC is powered with low temperature flue gas from an existing combined cycle plant. • Exergy destruction rate in integrated plant(IPP) is less than in combined plant. • Exit stack temperature of the IPP has less environmental thermal pollution. • Exergy and energy efficiencies of the IPP improved by 1.95% and 1.93%, respectively.

  14. Emergy and exergy analyses: Complementary methods or irreducible ideological options?

    International Nuclear Information System (INIS)

    Sciubba, Enrico; Ulgiati, Sergio

    2005-01-01

    The paper discusses the similarities and the incompatibilities between two forms of Energy Analysis (exergy and emergy, 'EXA' and 'EMA' in the following), both of which try to represent the behavior of physical systems by means of cumulative energy input/output methods that result in a double integration over space and time domains. Theoretical background, definitions and balance algebra are discussed first, in a 'statement-counterstatement' format that helps pinpointing differences and similarities. A significant, albeit simplified, benchmark case (ethanol production from corn) is used to compare the results and analytically assess the merits of each approach as well as possible synergic aspects. Corn production, transport and industrial conversion to ethanol are included in the analysis. First, mass balance and energy accounting are performed in each step of the process, then, exergy and emergy evaluations are carried out separately to lead to a set of performance indicators, the meaning of which is discussed with reference to their proper scale of application. The Authors underline that each method has its own preferred field of application and conclude that the two approaches appear to be characterized not much as different (and therefore competing) tools, but as different paradigms, whose meta-levels (their 'philosophies') substantially differ. In particular, EXA is found to provide the most correct and insightful assessment of thermodynamic features of any process and to offer a clear quantitative indication of both the irreversibilities and the degree of matching between the used resources and the end-use material or energy flows. EXA combined with costing considerations results in Thermo-Economics (TE), presently the best engineering method for System optimization. One of EXA recent extensions, Extended Exergy Accounting (EEA) includes all externalities in the exergy resource accounting, thus providing a more complete picture of how a process is interacting

  15. Energy and exergy analysis of a cruise ship

    DEFF Research Database (Denmark)

    Baldi, Francesco; Ahlgren, Fredrik; Nguyen, Tuong-Van

    2015-01-01

    but increasing share of the industry. The complexity of the energy system of a s hip where the energy required by propulsion is no longer the trivial main contributor to the whole energy use thus makes this kind of ship of particular interest for the analysis of how energy is converted from its original form...... destruction is generated in the Diesel engines and in the oil - fired boilers) and in the sea water cooler (5.4%) ; the main exergy losses happen instead in the exhaust gas, mostly from the main engines (6 7% of total losses) and particularly from those not equipped with heat recovery devices . The improved...

  16. Mathematical foundation of the optimization-based fluid animation method

    DEFF Research Database (Denmark)

    Erleben, Kenny; Misztal, Marek Krzysztof; Bærentzen, Jakob Andreas

    2011-01-01

    We present the mathematical foundation of a fluid animation method for unstructured meshes. Key contributions not previously treated are the extension to include diffusion forces and higher order terms of non-linear force approximations. In our discretization we apply a fractional step method to ...

  17. A refractometry-based glucose analysis of body fluids.

    Science.gov (United States)

    Zirk, Kai; Poetzschke, Harald

    2007-05-01

    In principle, refractometry appears to be a suitable method for the measurement of glucose concentrations in body fluids (such as blood and the intercellular fluid), even though the refractive index of the measured samples, as an additive property, is not specific. But, if certain conditions are fulfilled, the glucose content can be calculated using the refractive index in combination with values from a further measurement. This study describes the determination of the glucose content using refractometry in human blood serum derivates, which were selected - due to their ready availability - to be used as a model for interstitial fluid. Refractometry of body fluids requires the elimination of disturbing components from the measurement sample. First of all, a homogenous fluid (i.e. consisting of one phase) is required, so that all cells and components in suspension need to be separated out. Furthermore, certain dissolved macromolecular components which are known to disturb the measurement process must also be removed. In human serum samples which had been ultrafiltrated with a range of ultrafilters of different pore sizes, a comparative evaluation showed that only ultrafiltration through a filter with a separation limit of between 3 and 30kDa resulted in maximal reduction of the refractive index (compared to native serum), whereas ultrafilters with greater separation limits did not. The total content of osmotically active solutes (the tonicity) also exerts a clear influence. However, exemplary measurements in blood plasma fluid from one volunteer showed that the electrical conductivity is (without an additive component) directly proportional to the osmolality: physiological changes in the state of body hydration (hyperhydration and dehydration) do not lead to any considerable changes in the relation between ionised and uncharged solute particles, but instead result in a sufficiently clear dilution or concentration of the blood fluid's low molecular components. This

  18. Human Body Exergy Balance: Numerical Analysis of an Indoor Thermal Environment of a Passive Wooden Room in Summer

    Directory of Open Access Journals (Sweden)

    Koichi Isawa

    2015-09-01

    Full Text Available To obtain a basic understanding of the resultant changes in the human body exergy balance (input, consumption, storage, and output accompanying outdoor air temperature fluctuations, a “human body system and a built environmental system” coupled with numerical analysis was conducted. The built environmental system assumed a wooden room equipped with passive cooling strategies, such as thermal insulation and solar shading devices. It was found that in the daytime, the cool radiation exergy emitted by surrounding surfaces, such as walls increased the rate of human body exergy consumption, whereas the warm radiant exergy emitted by the surrounding surfaces at night decreased the rate of human body exergy consumption. The results suggested that the rates and proportions of the different components in the exergy balance equation (exergy input, consumption, storage, and output vary according to the outdoor temperature and humidity conditions.

  19. Effects of Floor Covering Resistance of a Radiant Floor on System Energy and Exergy Performances

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Shukuya, Masanori; Olesen, Bjarne W.

    2016-01-01

    Floor covering resistance (material and thickness) can be influenced by subjective choices (architectural design, interior design, texture, etc.) with significant effects on the performance of a radiant heating and cooling system. To study the effects of floor covering resistance on system...... performance, a water-based radiant floor heating and cooling system (dry, wooden construction) was considered to be coupled to an air-to-water heat pump, and the effects of varying floor covering resistances (0.05 m2K/W, 0.09 m2K/W and 0.15 m2K/W) on system performance were analyzed in terms of energy...... and exergy. In order to achieve the same heating and cooling outputs, higher average water temperatures are required in the heating mode (and lower temperatures in the cooling mode) with increasing floor covering resistance. These temperature requirements decrease the heat pump’s performance (lower...

  20. Exergy analysis of a combined heat and power plant with integrated lignocellulosic ethanol production

    DEFF Research Database (Denmark)

    Lythcke-Jørgensen, Christoffer Ernst; Haglind, Fredrik; Clausen, Lasse Røngaard

    2014-01-01

    production. An exergy analysis is carried out for a modelled polygeneration system in which lignocellulosic ethanol production based on hydrothermal pretreatment is integrated in an existing combined heat and power (CHP) plant. The ethanol facility is driven by steam extracted from the CHP unit when feasible...... district heating production in the ethanol facility. The results suggest that the efficiency of integrating lignocellulosic ethanol production in CHP plants is highly dependent on operation, and it is therefore suggested that the expected operation pattern of such polygeneration system is taken......Lignocellulosic ethanol production is often assumed integrated in polygeneration systems because of its energy intensive nature. The objective of this study is to investigate potential irreversibilities from such integration, and what impact it has on the efficiency of the integrated ethanol...

  1. Properties of forced convection experimental with silicon carbide based nano-fluids

    Science.gov (United States)

    Soanker, Abhinay

    With the advent of nanotechnology, many fields of Engineering and Science took a leap to the next level of advancements. The broad scope of nanotechnology initiated many studies of heat transfer and thermal engineering. Nano-fluids are one such technology and can be thought of as engineered colloidal fluids with nano-sized colloidal particles. There are different types of nano-fluids based on the colloidal particle and base fluids. Nano-fluids can primarily be categorized into metallic, ceramics, oxide, magnetic and carbon based. The present work is a part of investigation of the thermal and rheological properties of ceramic based nano-fluids. alpha-Silicon Carbide based nano-fluid with Ethylene Glycol and water mixture 50-50% volume concentration was used as the base fluid here. This work is divided into three parts; Theoretical modelling of effective thermal conductivity (ETC) of colloidal fluids, study of Thermal and Rheological properties of alpha-SiC nano-fluids, and determining the Heat Transfer properties of alpha-SiC nano-fluids. In the first part of this work, a theoretical model for effective thermal conductivity (ETC) of static based colloidal fluids was formulated based on the particle size, shape (spherical), thermal conductivity of base fluid and that of the colloidal particle, along with the particle distribution pattern in the fluid. A MATLAB program is generated to calculate the details of this model. The model is specifically derived for least and maximum ETC enhancement possible and thereby the lower and upper bounds was determined. In addition, ETC is also calculated for uniform colloidal distribution pattern. Effect of volume concentration on ETC was studied. No effect of particle size was observed for particle sizes below a certain value. Results of this model were compared with Wiener bounds and Hashin- Shtrikman bounds. The second part of this work is a study of thermal and rheological properties of alpha-Silicon Carbide based nano-fluids

  2. Complex fluid network optimization and control integrative design based on nonlinear dynamic model

    International Nuclear Information System (INIS)

    Sui, Jinxue; Yang, Li; Hu, Yunan

    2016-01-01

    In view of distribution according to complex fluid network’s needs, this paper proposed one optimization computation method of the nonlinear programming mathematical model based on genetic algorithm. The simulation result shows that the overall energy consumption of the optimized fluid network has a decrease obviously. The control model of the fluid network is established based on nonlinear dynamics. We design the control law based on feedback linearization, take the optimal value by genetic algorithm as the simulation data, can also solve the branch resistance under the optimal value. These resistances can provide technical support and reference for fluid network design and construction, so can realize complex fluid network optimization and control integration design.

  3. Implementation of an evidence-based guideline on fluid resuscitation: lessons learnt for future guidelines

    NARCIS (Netherlands)

    Tabbers, M.M.; Boluyt, N.; Offringa, M.

    2010-01-01

    There is little experience with the nationwide implementation of an evidence-based pediatric guideline on first-choice fluid for resuscitation in hypovolemia. We investigated fluid prescribing behavior at (1) guideline development, (2) after guideline development, and (3) after active implementation

  4. DNA hydrogel-based supercapacitors operating in physiological fluids

    Science.gov (United States)

    Hur, Jaehyun; Im, Kyuhyun; Hwang, Sekyu; Choi, ByoungLyong; Kim, Sungjee; Hwang, Sungwoo; Park, Nokyoung; Kim, Kinam

    2013-01-01

    DNA nanostructures have been attractive due to their structural properties resulting in many important breakthroughs especially in controlled assemblies and many biological applications. Here, we report a unique energy storage device which is a supercapacitor that uses nanostructured DNA hydrogel (Dgel) as a template and layer-by-layer (LBL)-deposited polyelectrolyte multilayers (PEMs) as conductors. Our device, named as PEM-Dgel supercapacitor, showed excellent performance in direct contact with physiological fluids such as artificial urine and phosphate buffered saline without any need of additional electrolytes, and exhibited almost no cytotoxicity during cycling tests in cell culture medium. Moreover, we demonstrated that the PEM-Dgel supercapacitor has greater charge-discharge cycling stability in physiological fluids than highly concentrated acid electrolyte solution which is normally used for supercapacitor operation. These conceptually new supercapacitors have the potential to be a platform technology for the creation of implantable energy storage devices for packageless applications directly utilizing biofluids. PMID:23412432

  5. Fluid emulsion base potential of shea butter | Oyedele | Journal of ...

    African Journals Online (AJOL)

    SB emulsion formulations were prepared from the fluid SB/LP blends by homogenizing each at 1:9 ratio (v/v) with potassium hydroxide (KOH) aqueous solution (0.1, 0.2, 0.4, or 0.6 M concentration, respectively), and with 0.2 M KOH at different mixing ratios (2:8, 3:7, 4:6, or 5:5 v/v), respectively. The physical consistency and ...

  6. Process analysis using the concept of intrinsic and extrinsic exergy losses

    International Nuclear Information System (INIS)

    Chang Hsuan; Chuang, S.-C.

    2003-01-01

    This paper introduces a two-level idealization concept and decomposes the exergy losses of processing operations into the intrinsic part and the extrinsic part. The first level idealization is the reversible operation and the second level idealization is the thermodynamic equilibrium operation. The exergy losses arising from the deviations from the first level idealization only, caused by configuration constraints, are defined as the intrinsic exergy losses. The extra exergy losses which arise from further deviations from the second level idealization, caused by transport rate limitations, are defined as the extrinsic exergy losses. Demonstrated by several example cases of different complex levels, the analysis results can pinpoint what and where to focus on for improvements: (1) design configurations or transport rate limitations, and (2) the specific locations within the operations or processes. As an example, for a de-ethanizer, the improvement measures on configuration-related and transport rate-related design conditions result in a 11.42% reduction of overall column intrinsic exergy loss and a 81.74% reduction of total individual stage extrinsic exergy loss

  7. Exergy and exergoeconomic analysis of a petroleum refinery utilities plant using the condensing to power method

    Energy Technology Data Exchange (ETDEWEB)

    Mendes da Silva, Julio Augusto; Pellegrini, Luiz Felipe; Oliveira Junior, Silvio [Polytechnic School of the University of Sao Paulo, SP (Brazil)], e-mails: jams@usp.br, luiz.pellegrini@usp.br, soj@usp.br; Plaza, Claudio; Rucker, Claudio [Petrobras - Petroleo Brasileiro S.A., Rio de Janeiro, RJ (Brazil)], e-mails: claudioplaza@petrobras.com.br, rucker@petrobras.com.br

    2010-07-01

    In this paper a brief description of the main processes present in a modern high capacity refinery is done. The methodology used to evaluate, through exergy analysis, the performance of the refinery's utilities plant since it is responsible for a very considerable amount of the total exergy destruction in a refinery is presented. The utilities plant products: steam, electricity, shaft power and high pressure water had their exergy unit cost determined using exergoeconomic approach. A simple and effective method called condensing to power was used to define the product of the condensers in exergy basis. Using this method it is possible to define the product of the condenser without the use of negentropy concept nor the aggregation of condensers to the steam turbines. By using this new approach, the costs obtained for the plant's products are exactly the same costs obtained when the condenser is aggregated to the steam turbine but with the advantage that the information about the stream between condenser and the steam turbine is not lost and the condenser can be evaluated singly. The analysis shows that the equipment where attention and resources should be focused are the boilers followed by the gas turbine, that together, are responsible for 80% of total exergy destruction in the utilities plant. The total exergy efficiency found for the utilities plant studied is 35% while more than 280 MW of exergy is destroyed in the utilities processes. (author)

  8. Fluid Dynamic Models for Bhattacharyya-Based Discriminant Analysis.

    Science.gov (United States)

    Noh, Yung-Kyun; Hamm, Jihun; Park, Frank Chongwoo; Zhang, Byoung-Tak; Lee, Daniel D

    2018-01-01

    Classical discriminant analysis attempts to discover a low-dimensional subspace where class label information is maximally preserved under projection. Canonical methods for estimating the subspace optimize an information-theoretic criterion that measures the separation between the class-conditional distributions. Unfortunately, direct optimization of the information-theoretic criteria is generally non-convex and intractable in high-dimensional spaces. In this work, we propose a novel, tractable algorithm for discriminant analysis that considers the class-conditional densities as interacting fluids in the high-dimensional embedding space. We use the Bhattacharyya criterion as a potential function that generates forces between the interacting fluids, and derive a computationally tractable method for finding the low-dimensional subspace that optimally constrains the resulting fluid flow. We show that this model properly reduces to the optimal solution for homoscedastic data as well as for heteroscedastic Gaussian distributions with equal means. We also extend this model to discover optimal filters for discriminating Gaussian processes and provide experimental results and comparisons on a number of datasets.

  9. Bartter syndrome prenatal diagnosis based on amniotic fluid biochemical analysis.

    Science.gov (United States)

    Garnier, Arnaud; Dreux, Sophie; Vargas-Poussou, Rosa; Oury, Jean-François; Benachi, Alexandra; Deschênes, Georges; Muller, Françoise

    2010-03-01

    Bartter syndrome is an autosomic recessive disease characterized by severe polyuria and sodium renal loss. The responsible genes encode proteins involved in electrolyte tubular reabsorption. Prenatal manifestations, mainly recurrent polyhydramnios because of fetal polyuria, lead to premature delivery. After birth, polyuria leads to life-threatening dehydration. Prenatal genetic diagnosis needs an index case. The aim of this study was to analyze amniotic fluid biochemistry for the prediction of Bartter syndrome. We retrospectively studied 16 amniotic fluids of Bartter syndrome-affected fetuses diagnosed after birth, only six of them being genetically proven. We assayed total proteins, alpha-fetoprotein, and electrolytes and defined a Bartter index corresponding to the multiplication of total protein and of alpha-fetoprotein. Results were compared with two control groups matched for gestational age-non-Bartter polyhydramnios (n = 30) and nonpolyhydramnios (n = 60). In Bartter syndrome, we observed significant differences (p Bartter index (0.16, 0.82, and 1.0, respectively). No statistical difference was observed for electrolytes. In conclusion, Bartter syndrome can be prenatally suspected on amniotic fluid biochemistry (sensitivity 93% and specificity 100%), allowing appropriate management before and after birth.

  10. Coal to SNG: Technical progress, modeling and system optimization through exergy analysis

    International Nuclear Information System (INIS)

    Li, Sheng; Ji, Xiaozhou; Zhang, Xiaosong; Gao, Lin; Jin, Hongguang

    2014-01-01

    Highlights: • Technical progresses of coal to SNG technologies are reported. • The entire coal to SNG system is modeled. • Coupling between SNG production and power generation is investigated. • Breakthrough points for further energy saving are determined. • System performance is optimized based on the first and second laws of thermodynamics. - Abstract: For both energy security and CO 2 emission reduction, synthetic natural gas (SNG) production from coal is an important path to implement clean coal technologies in China. In this paper, an overview of the progress of coal to SNG technologies, including the development of catalysts, reactor designs, synthesis processes, and systems integration, is provided. The coal to SNG system is modeled, the coupling between SNG production and power generation is investigated, the breakthrough points for further energy savings are determined, and the system performance is optimized based on the first and the second laws of thermodynamics. From the viewpoint of the first law of thermodynamics, the energy conversion efficiency of coal to SNG system can reach 59.8%. To reduce the plant auxiliary power, the breakthrough points are the development of low-energy-consumption oxygen production technology and gas purification technology or seeking new oxidants for coal gasification instead of oxygen. From the viewpoint of the second law of thermodynamics, the major exergy destruction in a coal to SNG system occurs in the coal gasification unit, SNG synthesis unit and the raw syngas cooling process. How to reduce the exergy destruction in these units is the key to energy savings and system performance enhancement. The conversion ratio of the first SNG synthesis reactor and the split ratio of the recycle gas are key factors that determine the performance of both the SNG synthesis process and the whole plant. A “turning point” phenomenon is observed: when the split ratio is higher than 0.90, the exergy destruction of the SNG

  11. Exergy storage to exploit solar energy in air conditioning

    Energy Technology Data Exchange (ETDEWEB)

    Navarrete-Gonzalez, J.J.; Torres-Reyes, E. [Guanajuato Univ., Guanajuato (Mexico). Inst. de Investigaciones Cientificas; Cervantes-de Gortari, J.G. [Univ. of Cuidad, Mexico City (Mexico). Dept. de Termoenergia y Mejoramiento Ambiental

    2006-07-01

    A thermodynamic procedure was developed to analyze the exergy of a rock bed thermal storage unit that used solar power to acclimatize a pig farm. Thermal behaviour was described by means of a control volume that included the entire system and assumed a unidirectional air flow and an adiabatic process. The thermodynamic properties of the system were determined as a function of the experimental temperature profiles developed during thermal storage from solar to thermal energy conversion provided by a solar collector at a fixed mass rate of air flow. Experimental data were used to calculate the energy yield and to determine the entropy generation inside the system. The aim of the study was to determine how well the thermodynamic model matched the real data obtained experimentally during normal operating conditions. Results indicated that an exergy accumulation existed inside the control volume, which was the net result of the energy gain during the heating process. However, entropy generation due to irreversibilities was studied for just 1 air flow. Further research is needed to establish a semi-empirical model of the process with the minimum of entropy generation. It was concluded that the thermal energy storage system was suitable for use in pig farms. 5 refs., 8 figs.

  12. Exergy analysis of a distillation tower for crude oil fractionation

    International Nuclear Information System (INIS)

    Rivero, R.

    1990-01-01

    In this paper the application of the exergy method to a crude oil atmospheric distillation tower is presented. The fundamentals and procedures are presented as well as the main parameters used to describe the thermodynamic performance of the system, such as Exergy Losses, Effectiveness and Improvement Potential. A parametric analysis of the influence on the effectiveness of the tower is then performed as a function of the number of trays, the amount of stripping steam, the use of reboilers and the operation pressure. The results obtained are discussed. As expected, the effectiveness of the tower increases with the overall number of trays in the tower and in the stripping columns for a constant operation pressure and a constant amount of stripping steam but there is a limit at which the pressure drop across the trays and the stripping steam requirements make the effectiveness decrease. The use of reboilers in the stripping columns adjacent to the main tower allows an increase in the effectiveness basically due to a greater heat integration. Finally, the increase in the operation pressure of the tower produces an increase of the effectiveness but also an increase in the stripping steam requirements

  13. Parametric study of an absorption refrigeration machine using advanced exergy analysis

    International Nuclear Information System (INIS)

    Gong, Sunyoung; Goni Boulama, Kiari

    2014-01-01

    An advanced exergy analysis of a water–lithium bromide absorption refrigeration machine was conducted. For each component of the machine, the proposed analysis quantified the irreversibility that can be avoided and the irreversibility that is unavoidable. It also identified the irreversibility originating from inefficiencies within the component and the irreversibility that does not originate from the operation of the considered component. It was observed that the desorber and absorber concentrated most of the exergy destruction. Furthermore, the exergy destruction at these components was found to be dominantly endogenous and unavoidable. A parametrical study has been presented discussing the sensitivity of the different performance indicators to the temperature at which the heat source is available, the temperature of the refrigerated environment, and the temperature of the cooling medium used at the condenser and absorber. It was observed that the endogenous avoidable exergy destruction at the desorber, i.e. the portion of the desorber irreversibility that could be avoided by improving the design and operation of the desorber, decreased when the heat source or the temperature at which the cooling effect was generated increased, and it decreased when the heat sink temperature increased. The endogenous avoidable exergy destruction at the absorber displayed the same variations, though it was observed to be less affected by the heat source temperature. Contrary to the aforementioned two components, the exergy destruction at the evaporator and condenser were dominantly endogenous and avoidable, with little sensitivity to the cycle operating parameters. - Highlights: • Endogenous, exogenous, avoidable and unavoidable irreversibilities were calculated for a water–LiBr absorption machine. • Overall, desorber and absorber concentrated most of the exergy destruction of the cycle. • The exergy destruction was mainly endogenous and unavoidable for the desorber and

  14. Thermodynamic energy and exergy analysis of three different engine combustion regimes

    International Nuclear Information System (INIS)

    Li, Yaopeng; Jia, Ming; Chang, Yachao; Kokjohn, Sage L.; Reitz, Rolf D.

    2016-01-01

    Highlights: • Energy and exergy distributions of three different combustion regimes are studied. • CDC demonstrates the highest utilization efficiency of heat transfer and exhaust. • HCCI achieves the highest energy and exergy efficiencies over CDC and RCCI. • HCCI and RCCI demonstrate lower exergy destruction than CDC. • Combustion temperature, rate, duration and regime affect exergy destruction. - Abstract: Multi-dimensional models were coupled with a detailed chemical mechanism to investigate the energy and exergy distributions of three different combustion regimes in internal combustion engines. The results indicate that the 50% heat release point (CA50) considerably affects fuel efficiency and ringing intensity (RI), in which RI is used to quantify the knock level. Moreover, the burn duration from the 10% heat release point (CA10) to CA50 dominates RI, and the position of 90% heat release point (CA90) affects fuel efficiency. The heat transfer losses of conventional diesel combustion (CDC) strongly depend on the local temperature gradient, while it is closely related to the heat transfer area for homogeneous charge compression ignition (HCCI) and reactivity controlled compression ignition (RCCI). Among the three combustion regimes, CDC has the largest utilization efficiency for heat transfer and exhaust energy due to its higher temperature in the heat transfer layer and higher exhaust pressure and temperature. The utilization efficiency of heat transfer and exhaust in RCCI is less affected by the variation of CA50 compared to those in CDC and HCCI. Exergy destruction is closely related to the homogeneity of in-cylinder temperature and equivalence ratio during combustion process, the combustion temperature, the chemical reaction rate, and the combustion duration. Under the combined effect, HCCI and RCCI demonstrate lower exergy destruction than CDC at the same load. Overall, the variations of the exergy distribution for the three combustion regimes

  15. Numerical analysis of splashing fluid using hybrid method of mesh-based and particle-based modelings

    International Nuclear Information System (INIS)

    Tanaka, Nobuatsu; Ogawara, Takuya; Kaneda, Takeshi; Maseguchi, Ryo

    2009-01-01

    In order to simulate splashing and scattering fluid behaviors, we developed a hybrid method of mesh-based model for large-scale continuum fluid and particle-based model for small-scale discrete fluid particles. As for the solver of the continuum fluid, we adopt the CIVA RefIned Multiphase SimulatiON (CRIMSON) code to evaluate two phase flow behaviors based on the recent computational fluid dynamics (CFD) techniques. The phase field model has been introduced to the CRIMSON in order to solve the problem of loosing phase interface sharpness in long-term calculation. As for the solver of the discrete fluid droplets, we applied the idea of Smoothed Particle Hydrodynamics (SPH) method. Both continuum fluid and discrete fluid interact each other through drag interaction force. We verified our method by applying it to a popular benchmark problem of collapse of water column problems, especially focusing on the splashing and scattering fluid behaviors after the column collided against the wall. We confirmed that the gross splashing and scattering behaviors were well reproduced by the introduction of particle model while the detailed behaviors of the particles were slightly different from the experimental results. (author)

  16. Carbon exergy tax applied to biomass integrated gasification combined cycle in sugarcane industry

    International Nuclear Information System (INIS)

    Fonseca Filho, Valdi Freire da; Matelli, José Alexandre; Perrella Balestieri, José Antonio

    2016-01-01

    The development of technologies based on energy renewable sources is increasing worldwide in order to diversify the energy mix and satisfy the rigorous environmental legislation and international agreements to reduce pollutant emission. Considering specific characteristics of biofuels available in Brazil, studies regarding such technologies should be carried out aiming energy mix diversification. Several technologies for power generation from biomass have been presented in the technical literature, and plants with BIGCC (biomass integrated gasification combined cycle) emerge as a major technological innovation. By obtaining a fuel rich in hydrogen from solid biomass gasification, BIGCC presents higher overall process efficiency than direct burning of the solid fuel in conventional boilers. The objective of this paper is to develop a thermodynamic and chemical equilibrium model of a BIGCC configuration for sugarcane bagasse. The model embodies exergetic cost and CO_2 emission analyses through the method of CET (carbon exergy tax). An exergetic penalty comparison between the BIGCC technology (with and without CO_2 capture and sequestration), a natural gas combined cycle and the traditional steam cycle of sugarcane sector is then presented. It is verified that the BIGCC configuration with CO_2 capture and sequestration presents technical and environmental advantages when compared to traditional technology. - Highlights: • We compared thermal cycles with the exergetic carbon exergy tax. • Thermal cycles with and without carbon capture and sequestration were considered. • Burned and gasified sugarcane bagasse was assumed as renewable fuel. • Exergetic carbon penalty tax was imposed to all studied configurations. • BIGCC with carbon sequestration revealed to be advantageous.

  17. Experimental investigation and exergy analysis on thermal storage integrated micro-cogeneration system

    International Nuclear Information System (INIS)

    Johar, Dheeraj Kishor; Sharma, Dilip; Soni, Shyam Lal; Gupta, Pradeep K.; Goyal, Rahul

    2017-01-01

    Highlights: • Energy Storage System is integrated with Micro cogeneration system. • Erythritol is used as Phase Change Material. • Maximum energy saved is 15.2%. • Maximum exergy saved is 4.22%. • Combined systems are feasible to increase energy and exergy efficiency. - Abstract: This paper describes the performance of thermal storage integrated micro-cogeneration system based on single cylinder diesel engine. In addition to electricity generated from genset, waste heat from hot exhaust of diesel engine was used to heat water in a double pipe heat exchanger of 67.70 cm length with inside tube diameter of 3.81 cm and outside tube diameter of 5.08 cm. Additionally, a latent heat thermal energy storage system was also integrated with this cogeneration system. A shell and tube type heat exchanger of 346 mm diameter and 420 mm height with 45 tubes of 18 mm diameter each was designed and fabricated, to store thermal energy, in which Erythritol (C_4H_1_0O_4) was used as phase changing material. The test results show that micro capacity (4.4 kW), stationary, single cylinder, diesel engine can be successfully utilized to simultaneously produce power as well as heating, and to also store thermal energy. Slight decrease in engine performance was observed when double pipe heat exchanger and latent heat thermal energy storage system was integrated with engine but the amount of energy which could be recovered was significant. Maximum percentage of energy saved was obtained at a load of 3.6 kW and was 15.2%.

  18. Performance of Partially-Hydrolyzed Polyacrylamide in Water Based Drilling Fluids

    Directory of Open Access Journals (Sweden)

    Ali Reza Nasiri*

    2013-05-01

    Full Text Available Fluid properties with constant improvement in efficiency have been noticeable as important criteria in drilling operation. The main drilling fluid properties highly depend on utilization of new polymers with high efficiency in drilling fluid composition. In this paper, the performance of a new polymer, called partially hydrolyzed polyacrylamide polymer (PHPA, is studied which has recently entered the drilling fluids industry in Iran. Hence viscosity property, fluid loss control and shale inhibition of this polymer have been evaluated based on an international standard method of API-13-I by considering the drilling and operational priorities of thecountry. Then the thermal effect, salt contaminants such as sodium chloride, calcium chloride, magnesium chloride and pH tolerance effect as major pollution indicators are also investigated in relation to polymeric fluid properties. The results obtained by the tests show that furthermore polymer PHPA increases rheological properties (apparent viscosity, plastic fluidity and yield point and it plays important role in increases in fluid loss. This polymer has also demonstrated acceptable resistance toward sodium chloride contaminants, but its efficiency decreases toward calcium and magnesium ion contaminants. The thermal tests show that polymer PHPA has high thermal stability up to 150°C. This polymer improves shale inhibition property and by encapsulation mechanism prevents dispersion of shale cuttings into the drilling fluid system as it stops any changes in fluid properties which will finally results inwellbore stability.

  19. Application of eco-exergy for assessment of ecosystem health and development of structurally dynamic models

    DEFF Research Database (Denmark)

    Zhang, J.; Gürkan, Zeren; Jørgensen, S.E.

    2010-01-01

    are developed using eco-exergy as the goal function, have been applied in explaining and exploring ecosystem properties and changes in community structure driven by biotic and abiotic factors. In this paper, we review the application of eco-exergy for the assessment of ecosystem health and development......Eco-exergy has been widely used in the assessment of ecosystem health, parameter estimations, calibrations, validations and prognoses. It offers insights into the understanding of ecosystem dynamics and disturbance-cl riven changes. Particularly, structurally dynamic models (SDMs), which...

  20. Analysis on exergy consumption patterns for space heating in Slovenian buildings

    DEFF Research Database (Denmark)

    Dovjak, Mateja; Shukuya, Masanori; Olesen, Bjarne W.

    2010-01-01

    and demand is taken into consideration. Exergy calculations enable us to analyze how much exergy is consumed in which part, from boiler to building envelope. They also reveal how much energy is supplied for the purpose of heating. Results show that insulation has much bigger effect than effect of boiler...... efficiency. However, the most effective solution is to improve building envelope together with boiler efficiency. Better thermal insulation also makes an important contribution to the improvement of thermal comfort conditions. It causes higher surface temperatures resulting in a larger warm radiant exergy...... emission rate and consequently better thermal comfort....

  1. Risk-based Comparative Study of Fluid Power Pitch Concepts

    DEFF Research Database (Denmark)

    Liniger, Jesper; Pedersen, Henrik Clemmensen; N. Soltani, Mohsen

    2017-01-01

    Proper functioning of the pitch system is essential to both normal operation and safety critical shut down of modern multi megawatt wind turbines. Several studies on field failure rates for such turbines show that pitch systems are a major contributor to failures which entails an increased risk....... Thus, more reliable and safe concepts are needed. A review of patents and patent applications covering fluid power pitch concepts, reveals that many propose closed-type hydraulic systems. This paper proposes a closed-type concept with a bootstrap reservoir. In contrary to a conventional system where...

  2. Energy and exergy efficiency comparison of horizontal and vertical axis wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Pope, K.; Dincer, I.; Naterer, G.F. [Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, Ontario (Canada)

    2010-09-15

    In this paper, an energy and exergy analysis is performed on four different wind power systems, including both horizontal and vertical axis wind turbines. Significant variability in turbine designs and operating parameters are encompassed through the selection of systems. In particular, two airfoils (NACA 63(2)-215 and FX 63-137) commonly used in horizontal axis wind turbines are compared with two vertical axis wind turbines (VAWTs). A Savonius design and Zephyr VAWT benefit from operational attributes in wind conditions that are unsuitable for airfoil type designs. This paper analyzes each system with respect to both the first and second laws of thermodynamics. The aerodynamic performance of each system is numerically analyzed by computational fluid dynamics software, FLUENT. A difference in first and second law efficiencies of between 50 and 53% is predicted for the airfoil systems, whereas 44-55% differences are predicted for the VAWT systems. Key design variables are analyzed and the predicted results are discussed. The exergetic efficiency of each wind turbine is studied for different geometries, design parameters and operating conditions. It is shown that the second law provides unique insight beyond a first law analysis, thereby providing a useful design tool for wind power development. (author)

  3. Towards modeling of combined cooling, heating and power system with artificial neural network for exergy destruction and exergy efficiency prognostication of tri-generation components

    International Nuclear Information System (INIS)

    Taghavifar, Hadi; Anvari, Simin; Saray, Rahim Khoshbakhti; Khalilarya, Shahram; Jafarmadar, Samad; Taghavifar, Hamid

    2015-01-01

    The current study is an attempt to address the investigation of the CCHP (combined cooling, heating and power) system when 10 input variables were chosen to analyze 10 most important objective output parameters. Moreover, ANN (artificial neural network) was successfully applied on the tri-generation system on account of its capability to predict responses with great confidence. The results of sensitivity analysis were considered as foundation for selecting the most suitable and potent input parameters of the supposed cycle. Furthermore, the best ANN topology was attained based on the least amount of MSE and number of iterations. Consequently, the trainlm (Levenberg–Marquardt) training approach with 10-9-10 configuration has been exploited for ANN modeling in order to give the best output correspondence. The maximum MRE = 1.75% (mean relative error) and minimum R 2  = 0.984 represents the reliability and outperformance of the developed ANN over common conventional thermodynamic analysis carried out by EES (engineering equation solver) software. - Highlights: • Exergy analysis is undertaken for CCHP components based on operative factors. • ANN tool is applied to obtained database from thermodynamic analyses session. • The best ANN topology is detected at 10-9-10 with trainlm learning algorithm. • The input and output layer parameters were selected based on sensitivity analysis.

  4. A field application of nanoparticle-based invert emulsion drilling fluids

    Energy Technology Data Exchange (ETDEWEB)

    Borisov, Alexey S.; Husein, Maen, E-mail: mhusein@ucalgary.ca [University of Calgary, Department of Chemical & Petroleum Engineering (Canada); Hareland, Geir [Oklahoma State University, Department of Chemical Engineering (United States)

    2015-08-15

    Application of nanotechnology in drilling fluids for the oil and gas industry has been a focus of several recent studies. A process for the in situ synthesis of nanoparticles (NPs) into drilling fluids has been developed previously in our group and showed that calcium-based NPs (CNPs) and iron-based NPs (INPs), respectively, with concentrations of 0.5–2.0 wt% can dramatically improve filtration properties of commercial drilling fluids in a laboratory environment. In this work, a modified process for the emulsion-based synthesis of NPs on a 20 m{sup 3} volume and its subsequent full-scale field testing are presented. Comparison between NP carrier fluids prepared under controlled environment in the laboratory and those prepared on a large scale in a mixing facility revealed very little variation in the main characteristics of the drilling fluid; including the size of the solid constituents. Transmission electron microscopy photographs suggest an average CNP particle size in the carrier fluid of 51 ± 11 nm. Results from the full-scale field test showed that total mud losses while drilling with CNP-based invert emulsion were on average 27 % lower than in the case of conventional fluids. This loss prevention falls within the range observed in the laboratory.

  5. Numerical study of cullet glass subjected to microwave heating and SiC susceptor effects. Part II: Exergy transfer analysis

    International Nuclear Information System (INIS)

    Acevedo, Luis; Usón, Sergio; Uche, Javier

    2015-01-01

    Highlights: • Exergy transfer analysis is proposed for the analysis of microwave glass heating. • Distribution of exergy transferred, accumulated and destroyed is quantified. • The method is applied to the comparison of different susceptor positions. - Abstract: The mathematical model of exergy transfer in cullet glass heated by microwave inside of a cubical cavity with the aid of a susceptor is presented. Part I of this paper presented a numerical combined electromagnetic and heat transfer model by applying both transient Maxwell’s equations and heat transfer equations. Then, the electromagnetic and temperature fields were used to obtain the exergy transfer analysis in the oven. Exergy transfer analysis informs us about the efficiency of energy transformations taking place during the heating process, since it explains how the quality of the energy behaves along the heating process. The rate of internal exergy, exergy flowing and destroyed exergy were obtained and presented for this transient process. Part I showed that the susceptor location could change the temperature fields of cullet glass. So, an exergy analysis is important to understand the irreversibilities produced by a susceptor during preheating (microwaves activation) and heating process of the cullet glass, and how they could be minimized. Exergy transfer analysis shows how both, electromagnetic and heat transfer, are responsible of the irreversibilities generated in the heating process

  6. Respiratory Adaptations in Acid-base Disturbances: Role of Cerebral Fluids,

    Science.gov (United States)

    1979-06-19

    The respiratory and metabolic components of acid-base homeostasis are defined. A quantitative empirical description of the (incomplete) mutual...literature. Respiratory adaptations in steady acid-base disturbances of metabolic origin (hyperventilation with hypocapnia in primary metabolic acidosis, and...hypoventilation with hypercapnia in metabolic alkalosis ) are analyzed as a function of the acidity of the cerebral fluids (cerebrospinal and cerebral interstitial fluid). (Author)

  7. Predicting fluid responsiveness with transthoracic echocardiography is not yet evidence based

    DEFF Research Database (Denmark)

    Wetterslev, M; Haase, N; Johansen, R R

    2013-01-01

    an integrated tool in the intensive care unit, this systematic review examined studies evaluating the predictive value of TTE for fluid responsiveness. In October 2012, we searched Pubmed, EMBASE and Web of Science for studies evaluating the predictive value of TTE-derived variables for fluid responsiveness...... responsiveness. Of the 4294 evaluated citations, only one study fully met our inclusion criteria. In this study, the predictive value of variations in inferior vena cava diameter (> 16%) for fluid responsiveness was moderate with sensitivity of 71% [95% confidence interval (CI) 44-90], specificity of 100% (95......% CI 73-100) and an area under the receiver operating curve of 0.90 (95% CI 0.73-0.98). Only one study of TTE-based methods fulfilled the criteria for valid assessment of fluid responsiveness. Before recommending the use of TTE in predicting fluid responsiveness, proper evaluation including...

  8. Oil base fluids without tensoactive additives; Fluidos a base de oleo sem tensoativos

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Jose Carlos V; Aragao, Atila Fernando L [PETROBRAS, XX (Brazil). Centro de Desenvolvimento de Recursos Humanos Norte e Nordeste

    1990-12-31

    The goal of this paper is to define an ideal oil base fluid composition without tensoactive additives, since these may cause damage to producing formation during drilling or well completion. We investigated the rheological, filtrating and phase separation properties of the systems composed of diesel oil, organophilic clay and a polar agent (water or ethyl alcohol). In order to to that, we used the 286 Baroid digital rotating viscometer, filtrating cells standardized according to the American Petroleum Institute (AP) for temperatures of 25 deg C to 149 deg C and pressures of 6,89 x 10{sup 5} Pa (100 psig) to 3,44 x 10{sup 6} (500 psig), and the setting method, according to the determinations of respectively rheological, filtrating and phase separation parameters. Results proved that the composition: diesel oil-94% v/v, Na Cl saturated solution - 6% v/v and bentone - 17,1 to 22,8 kg/m{sup 3} (6 to 8 lb/bbl), is ideal to meet the properties required for drilling and well completion operations for low densities, that is 0,84% to 1,02 (6,9 to 8,5 ib/gal). In order to obtain densities in the interval of 1,02 to 1,14 (8,5 to 9,5 ib/gal) the system should be condensed with calcite (Ca CO{sub 3}) and the base fluid composition should be : diesel oil-94 to 98% v/v, Na Cl saturated solution - 2 to 6% v/v and bentone 17,1 to 22,8 kg/m{sup 3} (6 to 8 ib/bbl). The average cost per barrel for the systems studied here is of the same order of conventional oil base fluids (with tensoactive additives). (author) 13 refs., 7 figs., 3 tabs.

  9. Oil base fluids without tensoactive additives; Fluidos a base de oleo sem tensoativos

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Jose Carlos V.; Aragao, Atila Fernando L. [PETROBRAS, XX (Brazil). Centro de Desenvolvimento de Recursos Humanos Norte e Nordeste

    1989-12-31

    The goal of this paper is to define an ideal oil base fluid composition without tensoactive additives, since these may cause damage to producing formation during drilling or well completion. We investigated the rheological, filtrating and phase separation properties of the systems composed of diesel oil, organophilic clay and a polar agent (water or ethyl alcohol). In order to to that, we used the 286 Baroid digital rotating viscometer, filtrating cells standardized according to the American Petroleum Institute (AP) for temperatures of 25 deg C to 149 deg C and pressures of 6,89 x 10{sup 5} Pa (100 psig) to 3,44 x 10{sup 6} (500 psig), and the setting method, according to the determinations of respectively rheological, filtrating and phase separation parameters. Results proved that the composition: diesel oil-94% v/v, Na Cl saturated solution - 6% v/v and bentone - 17,1 to 22,8 kg/m{sup 3} (6 to 8 lb/bbl), is ideal to meet the properties required for drilling and well completion operations for low densities, that is 0,84% to 1,02 (6,9 to 8,5 ib/gal). In order to obtain densities in the interval of 1,02 to 1,14 (8,5 to 9,5 ib/gal) the system should be condensed with calcite (Ca CO{sub 3}) and the base fluid composition should be : diesel oil-94 to 98% v/v, Na Cl saturated solution - 2 to 6% v/v and bentone 17,1 to 22,8 kg/m{sup 3} (6 to 8 ib/bbl). The average cost per barrel for the systems studied here is of the same order of conventional oil base fluids (with tensoactive additives). (author) 13 refs., 7 figs., 3 tabs.

  10. Performance of the mineral blended ester oil-based drilling fluid systems

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, A.R.; Kamis, A.; Foo, K.S. [University Teknologi (Malaysia)

    2001-06-01

    A study was conducted in which the properties of ester oil-based drilling fluid systems were examined using a blended mixture of ester and synthetic mineral oil. Biodegradable invert emulsion ester-based fluids are preferred over mineral oil-based drilling fluids for environmental reasons, but they tend to cause alkaline hydrolysis resulting in solidification of the drilling fluid systems. The drilling fluid examined here consisted of Malaysian palm oil ester derivatives (methyl laureate ester or isopropyl laureate ester) blended with commercially available synthetic mineral oil. This mineral oil was added to reduce the problem of alkaline hydrolysis. This mixture, however, was found to be unstable and could not solve the problem at high temperature. The isopropyl laureate and mineral oil blended system was more stable towards the hydrolysis process up to 250 degrees F. In order to enhance the performance of an invert emulsion drilling fluid system, it was recommended that brine water content of the fluid system be lowered. 3 refs., 2 figs.

  11. Preliminary assessment of water-based nano-fluids for use as coolants in PWRs

    International Nuclear Information System (INIS)

    Jacopo Buongiorno

    2005-01-01

    Full text of publication follows: The impact of using water-based fluids with small additions (<2% vol.) of nano-sized (10-100 nm) particle populations as coolants for current and advanced PWRs is evaluated. Such 'engineered' fluids (known as nano-fluids) are attractive because the presence of the nano-particles enhances energy transport considerably. As a result, nano-fluids are known to have (i) higher thermal conductivity than water (up to 20% depending on nano-particle material, size and volumetric fraction), (ii) higher heat transfer coefficients (up to 40%), (iii) higher CHF (up to 300% in pool boiling), and (iv) comparable pressure drop. Furthermore, nano-fluids appear to be very stable suspensions with little or no sedimentation, because of the small size of the dispersed particles and their typically low volumetric fractions. The ultimate objective of this work is to assess whether existing PWRs could be retro-fitted with a water-based nano-fluid coolant, to increase safety margins, reduce stored energy, and/or allow for power up-rates. Also, advanced PWRs could be designed with nano-fluids. The linear heat generation rate in PWRs is limited by a) fuel centerline melting, b) cladding overheating (CHF), and c) stored energy release following a large-break LOCA. Mechanisms b) and c) are usually the most limiting. For given geometry and linear power, it is obvious that the core with the nano-fluid coolant will have higher margins to CHF and LOCA limits. Conversely, for given margins, a higher linear power can be accommodated by the nano-fluid-cooled core. Standard thermal-hydraulic models for the PWR hot fuel pin (including a RELAP model for the LOCA) have been used to quantify the benefit of using nano-fluid coolants on the performance of a PWR. (author)

  12. Exergy and thermoeconomic evaluation of hydrogen production from natural gas; Avaliacao exergetica e termo-economica da producao de hidrogenio a partir do gas natural

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Flavio Eduardo da [PROMON Engenharia Ltda., Sao Paulo, SP (Brazil); Oliveira Junior, Silvio de [Universidade de Sao Paulo (USP), SP (Brazil). Escola Politecnica

    2008-07-01

    Some specific processes are required to obtain pure hydrogen and the most usual one is the natural gas reforming, where natural gas reacts with superheated steam producing H{sub 2}, CO, CO{sub 2} and H{sub 2}O. This paper presents exergy and thermoeconomic analysis of a complete hydrogen production unit of a petroleum refinery. The hydrogen production unit analysed in this paper has to supply 550,000 Nm{sup 3} of hydrogen per day to purify diesel oil. Based on a synthesis plant of the hydrogen production unit, the exergy efficiency of each component and of the overall plant are calculated. The hydrogen production cost is determined by means of a thermoeconomic analysis in which the equality cost partition method is employed, including capital and operational costs, in order to determine the production cost of hydrogen and other products of the plant.(author)

  13. Physical Hydronomics: Application of the exergy analysis to the assessment of environmental costs of water bodies. The case of the inland basins of Catalonia

    International Nuclear Information System (INIS)

    Valero, Antonio; Uche, Javier; Valero, Alicia; Martinez, Amaya

    2009-01-01

    The water cycle is governed by the thermodynamic laws. Therefore Thermodynamics and more specifically Exergoecology, that is the application of the exergy analysis in the evaluation of natural fluxes and resources on Earth, could help to build a solid cost structure based strictly on Physics and far away from price policies or subjectivities. Any type of degradation of water bodies along their rivers, lakes, etc., could then be quantified. Moreover, the physical information of the resource can be unified into universal units (energy units), and the monetary conversion of exergy costs is automatic through conventional energy prices. This paper presents a new discipline named 'Physical Hydronomics', as a guide to assess environmental costs included in the European Water Framework Directive (WFD).

  14. A Quality Function Deployment-Based Model for Cutting Fluid Selection

    Directory of Open Access Journals (Sweden)

    Kanika Prasad

    2016-01-01

    Full Text Available Cutting fluid is applied for numerous reasons while machining a workpiece, like increasing tool life, minimizing workpiece thermal deformation, enhancing surface finish, flushing away chips from cutting surface, and so on. Hence, choosing a proper cutting fluid for a specific machining application becomes important for enhanced efficiency and effectiveness of a manufacturing process. Cutting fluid selection is a complex procedure as the decision depends on many complicated interactions, including work material’s machinability, rigorousness of operation, cutting tool material, metallurgical, chemical, and human compatibility, reliability and stability of fluid, and cost. In this paper, a decision making model is developed based on quality function deployment technique with a view to respond to the complex character of cutting fluid selection problem and facilitate judicious selection of cutting fluid from a comprehensive list of available alternatives. In the first example, HD-CUTSOL is recognized as the most suitable cutting fluid for drilling holes in titanium alloy with tungsten carbide tool and in the second example, for performing honing operation on stainless steel alloy with cubic boron nitride tool, CF5 emerges out as the best honing fluid. Implementation of this model would result in cost reduction through decreased manpower requirement, enhanced workforce efficiency, and efficient information exploitation.

  15. A magneto-rheological fluid-based torque sensor for smart torque wrench application

    Science.gov (United States)

    Ahmadkhanlou, Farzad; Washington, Gregory N.

    2013-04-01

    In this paper, the authors have developed a new application where MR fluid is being used as a sensor. An MR-fluid based torque wrench has been developed with a rotary MR fluid-based damper. The desired set torque ranges from 1 to 6 N.m. Having continuously controllable yield strength, the MR fluid-based torque wrench presents a great advantage over the regular available torque wrenches in the market. This design is capable of providing continuous set toque from the lower limit to the upper limit while regular torque wrenches provide discrete set torques only at some limited points. This feature will be especially important in high fidelity systems where tightening torque is very critical and the tolerances are low.

  16. Microdroplet-based universal logic gates by electrorheological fluid

    KAUST Repository

    Zhang, Mengying

    2011-01-01

    We demonstrate a uniquely designed microfluid logic gate with universal functionality, which is capable of conducting all 16 logic operations in one chip, with different input voltage combinations. A kind of smart colloid, giant electrorheological (GER) fluid, functions as the translation media among fluidic, electronic and mechanic information, providing us with the capability of performing large integrations either on-chip or off-chip, while the on-chip hybrid circuit is formed by the interconnection of the electric components and fluidic channels, where the individual microdroplets travelling in a channel represents a bit. The universal logic gate reveals the possibilities of achieving a large-scale microfluidic processor with more complexity for on-chip processing for biological, chemical as well as computational experiments. © 2011 The Royal Society of Chemistry.

  17. Emergy and Eco-exergy Evaluation of Four Forest Restoration Modes

    Science.gov (United States)

    Four different forest restoration modes (Acacia mangium plantation, mixed-native species plantation, conifer plantation and Eucalyptus plantation) were evaluated using Energy System Theory and the emergy synthesis method. In addition, the eco-exergies of the four forest restorati...

  18. The thermodynamic properties of the upper continental crust: Exergy, Gibbs free energy and enthalpy

    International Nuclear Information System (INIS)

    Valero, Alicia; Valero, Antonio; Vieillard, Philippe

    2012-01-01

    This paper shows a comprehensive database of the thermodynamic properties of the most abundant minerals of the upper continental crust. For those substances whose thermodynamic properties are not listed in the literature, their enthalpy and Gibbs free energy are calculated with 11 different estimation methods described in this study, with associated errors of up to 10% with respect to values published in the literature. Thanks to this procedure we have been able to make a first estimation of the enthalpy, Gibbs free energy and exergy of the bulk upper continental crust and of each of the nearly 300 most abundant minerals contained in it. Finally, the chemical exergy of the continental crust is compared to the exergy of the concentrated mineral resources. The numbers obtained indicate the huge chemical exergy wealth of the crust: 6 × 10 6 Gtoe. However, this study shows that approximately only 0.01% of that amount can be effectively used by man.

  19. Energy–exergy and economic analyses of a hybrid solar–hydrogen renewable energy system in Ankara, Turkey

    International Nuclear Information System (INIS)

    Ozden, Ender; Tari, Ilker

    2016-01-01

    Highlights: • Uninterrupted energy in an emergency blackout situation. • System modeling of a solar–hydrogen based hybrid renewable energy system. • A comprehensive thermodynamical analysis. • Levelized cost of electricity analysis for a project lifetime of 25 years. - Abstract: A hybrid (Solar–Hydrogen) stand-alone renewable energy system that consists of photovoltaic panels (PV), Proton Exchange Membrane (PEM) fuel cells, PEM based electrolyzers and hydrogen storage is investigated by developing a complete model of the system using TRNSYS. The PV panels are mounted on a tiltable platform to improve the performance of the system by monthly adjustments of the tilt angle. The total area of the PV panels is 300 m 2 , the PEM fuel cell capacity is 5 kW, and the hydrogen storage is at 55 bars pressure and with 45 m 3 capacity. The main goal of this study is to verify that the system meets the electrical power demand of the emergency room without experiencing a shortage for a complete year in an emergency blackout situation. For this purpose, after modeling the system, energy and exergy analyses for the hydrogen cycle of the system for a complete year are performed, and the energy and exergy efficiencies are found as 4.06% and 4.25%, respectively. Furthermore, an economic analysis is performed for a project lifetime of 25 years based on Levelized Cost of Electricity (LCE), and the LCE is calculated as 0.626 $/kWh.

  20. Exergy costs analysis of water desalination and purification techniques by transfer functions

    International Nuclear Information System (INIS)

    Carrasquer, Beatriz; Martínez-Gracia, Amaya; Uche, Javier

    2016-01-01

    Highlights: • A procedure to estimate the unit exergy cost of water treatment techniques is provided. • Unit exergy costs of water purification and desalination are given as a function of design and operating parameters. • Unit exergy costs range from 3.3 to 6.8 in purification and from 2 to 26 in desalination. • They could be used in their preliminary design as good indicators of their energy efficiency. - Abstract: The unit exergy costs of desalination and purification, which are two alternatives commonly used for water supply and treatment, have been characterized as a function of the energy efficiency of the process by combining the Exergy Cost Analysis with Transfer Function Analysis. An equation to assess the exergy costs of these alternatives is then proposed as a quick guide to know the energy efficiency of any water treatment process under different design and operating conditions. This combination, was satisfactory applied to groundwaters and water transfers. After identifying the boundaries of the system, input and output flows are calculated in exergy values. Next, different examples are analyzed in order to propose a generic equation to assess the exergy cost of the water restoration technologies, attending to their main features. Recovery ratio, energy requirements and salts concentrations (for desalination), and plant capacity and organic matter recovery (for water purification) are introduced in the calculations as their main endogenous parameters. Values obtained for typical operation ranges of commercial plants showed that unit exergy costs of water purification ranged from 3.3 to 6.8; maximum values, as expected, were found at low plant capacities and high organic matter removal ratios. For water desalination, values varied from 2 to 7 in membrane technologies and from 10 to 26 in thermal processes. The recovery ratio and salts concentration in raw water increased the unit exergy costs in membrane techniques. In distillation processes

  1. Compliance of secondary production and eco-exergy as indicators of benthic macroinvertebrates assemblages' response to canopy cover conditions in Neotropical headwater streams.

    Science.gov (United States)

    Linares, Marden Seabra; Callisto, Marcos; Marques, João Carlos

    2018-02-01

    Riparian vegetation cover influences benthic assemblages structure and functioning in headwater streams, as it regulates light availability and autochthonous primary production in these ecosystems.Secondary production, diversity, and exergy-based indicators were applied in capturing how riparian cover influences the structure and functioning of benthic macroinvertebrate assemblages in tropical headwater streams. Four hypotheses were tested: (1) open canopy will determine the occurrence of higher diversity in benthic macroinvertebrate assemblages; (2) streams with open canopy will exhibit more complex benthic macroinvertebrate communities (in terms of information embedded in the organisms' biomass); (3) in streams with open canopy benthic macroinvertebrate assemblages will be more efficient in using the available resources to build structure, which will be reflected by higher eco-exergy values; (4) benthic assemblages in streams with open canopy will exhibit more secondary productivity. We selected eight non-impacted headwater streams, four shaded and four with open canopy, all located in the Neotropical savannah (Cerrado) of southeastern Brazil. Open canopy streams consistently exhibited significantly higher eco-exergy and instant secondary production values, exemplifying that these streams may support more complex and productive benthic macroinvertebrate assemblages. Nevertheless, diversity indices and specific eco-exergy were not significantly different in shaded and open canopy streams. Since all the studied streams were selected for being considered as non-impacted, this suggests that the potential represented by more available food resources was not used to build a more complex dissipative structure. These results illustrate the role and importance of the canopy cover characteristics on the structure and functioning of benthic macroinvertebrate assemblages in tropical headwater streams, while autochthonous production appears to play a crucial role as food

  2. Energy and exergy analyses of native cassava starch drying in a tray dryer

    International Nuclear Information System (INIS)

    Aviara, Ndubisi A.; Onuoha, Lovelyn N.; Falola, Oluwakemi E.; Igbeka, Joseph C.

    2014-01-01

    Energy and exergy analyses of native cassava starch drying in a tray dryer were carried out to assess the performance of the system in terms of energy utilization, energy utilization ratio, energy efficiency, exergy inflow and outflow, exergy loss and exegetic efficiency. The results indicated that for the starch with ash content of 0.76%, 0.85% crude protein, 0.16% crude fat, negligible amount of fiber, average granule size of 14.1 μm, pH of 5.88, amylose content of 23.45% and degree of crystallinity of 22.34%, energy utilization and energy utilization ratio increased from 1.93 to 5.51 J/s and 0.65 to 0.6 as the drying temperature increased from 40 to 60 °C. Energy efficiency increased from 16.036 to 30.645%, while exergy inflow, outflow and losses increased from 0.399 to 2.686, 0.055 to 0.555 and 0.344 to 2.131 J/s respectively in the above temperature range. Exergetic efficiency increased with increase in both drying air temperature and energy utilization and was lower than energy efficiency. Exergetic improvement potential also increased with increase in drying air temperature. Model equations that could be used to express the energy and exergy parameters as a function of drying temperature were established. - Highlights: • Energy and exergy analyses of cassava starch drying in a tray dryer were carried out. • Energy utilization increased with drying temperature. • Energy efficiency was higher than exergy efficiency. • Energy and exergy efficiencies increased with increase in temperature. • Improvement potential increased with increase in temperature

  3. Overall energy, exergy and carbon credit analysis by different type of hybrid photovoltaic thermal air collectors

    International Nuclear Information System (INIS)

    Agrawal, Sanjay; Tiwari, G.N.

    2013-01-01

    Highlights: ► Comparative study of PVT air collectors. ► CO 2 analysis of all type of PVT air collectors. ► Study of thermal energy, exergy gain and exergy efficiency. ► Exergy efficiency of unglazed hybrid PVT tiles air collector is most efficient. - Abstract: In this paper, comparative analysis of different type of photovoltaic thermal (PVT) air collector namely: (i) unglazed hybrid PVT tiles, (ii) glazed hybrid PVT tiles and (iii) conventional hybrid PVT air collectors have been carried out for the composite climate of Srinagar (India). The comparative study has been carried out in terms of overall thermal energy and exergy gain, exergy efficiency and carbon credit earned by different type of hybrid PVT air collectors. It has been observed that overall annual thermal energy and exergy gain of unglazed hybrid PVT tiles air collector is higher by 27% and 29.3% respectively as compared to glazed hybrid PVT tiles air collector and by 61% and 59.8% respectively as compared to conventional hybrid PVT air collector. It has also been observed that overall annual exergy efficiency of unglazed and glazed hybrid PVT tiles air collector is higher by 9.6% and 53.8% respectively as compared to conventional hybrid PVT air collector. On the basis of comparative study, it has been concluded that CO 2 emission reduction per annum on the basis of overall thermal energy gain of unglazed and glazed hybrid PVT tiles air collector is higher by 62.3% and 27.7% respectively as compared to conventional hybrid PVT air collector and on the basis of overall exergy gain it is 59.7% and 22.7%.

  4. Exergy analysis for stationary flow systems with several heat exchange temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Lampinen, M J; Heikkinen, M A [Helsinki Univ. of Technology, Espoo (Finland). Dept. of Energy Engineering

    1995-07-01

    A thermodynamic theory of exergy analysis for a stationary flow system having several heat inputs and outputs at different temperature levels is presented. As a new result a relevant reference temperature of the surroundings is derived for each case. Also a general formula which combines exergy analysis with a modified Carnot efficiency is derived. The results are illustrated by numerical examples for mechanical multi-circuit heat pump cycles, for a Brayton process and for an absorption heat pump. (Author)

  5. Exergy analysis of parabolic trough solar collectors integrated with combined steam and organic Rankine cycles

    International Nuclear Information System (INIS)

    Al-Sulaiman, Fahad A.

    2014-01-01

    Highlights: • As the solar irradiation increases, the exergetic efficiency increases. • The R134a combined cycle has best exergetic performance, 26%. • The R600a combined cycle has the lowest exergetic efficiency, 20%. • The main source of exergy destruction is the solar collector. • There is an exergetic improvement potential of 75% in the systems considered. - Abstract: In this paper, detailed exergy analysis of selected thermal power systems driven by parabolic trough solar collectors (PTSCs) is presented. The power is produced using either a steam Rankine cycle (SRC) or a combined cycle, in which the SRC is the topping cycle and an organic Rankine cycle (ORC) is the bottoming cycle. Seven refrigerants for the ORC were examined: R134a, R152a, R290, R407c, R600, R600a, and ammonia. Key exergetic parameters were examined: exergetic efficiency, exergy destruction rate, fuel depletion ratio, irreversibility ratio, and improvement potential. For all the cases considered it was revealed that as the solar irradiation increases, the exergetic efficiency increases. Among the combined cycles examined, the R134a combined cycle demonstrates the best exergetic performance with a maximum exergetic efficiency of 26% followed by the R152a combined cycle with an exergetic efficiency of 25%. Alternatively, the R600a combined cycle has the lowest exergetic efficiency, 20–21%. This study reveals that the main source of exergy destruction is the solar collector where more than 50% of inlet exergy is destructed, or in other words more than 70% of the total destructed exergy. In addition, more than 13% of the inlet exergy is destructed in the evaporator which is equivalent to around 19% of the destructed exergy. Finally, this study reveals that there is an exergetic improvement potential of 75% in the systems considered

  6. Exergy and Energy Analysis of Low Temperature District Heating Network

    DEFF Research Database (Denmark)

    Li, Hongwei; Svendsen, Svend

    is in line with a pilot project that is carrying out in Denmark with network supply/return temperature at 55oC/25 oC. The consumer domestic hot water (DHW) demand is supplied with a special designed district heating (DH) storage tank. The space heating (SH) demand is supplied with a low temperature radiator......Low temperature district heating (LTDH) with reduced network supply and return temperature provides better match of the low quality building thermal demand and the low quality waste heat supply. In this paper, an exemplary LTDH network was designed for 30 low energy demand residential houses, which....... The network thermal and hydraulic conditions were simulated under steady state with an in-house district heating network design and simulation code. Through simulation, the overall system energetic and exergetic efficiencies were calculated and the exergy losses for the major district heating system...

  7. Energy and exergy analysis of low temperature district heating network

    DEFF Research Database (Denmark)

    Li, Hongwei; Svendsen, Svend

    2012-01-01

    is designed to supply heating for 30 low energy detached residential houses. The network operational supply/return temperature is set as 55 °C/25 °C, which is in line with a pilot project carried out in Denmark. Two types of in-house substations are analyzed to supply the consumer domestic hot water demand...... energy/exergy losses and increase the quality match between the consumer heating demand and the district heating supply.......Low temperature district heating with reduced network supply and return temperature provides better match of the low quality building heating demand and the low quality heating supply from waste heat or renewable energy. In this paper, a hypothetical low temperature district heating network...

  8. Numerical analysis and field study of time dependent exergy-energy of a gas-steam combined cycle

    Directory of Open Access Journals (Sweden)

    Barari Bamdad

    2012-01-01

    Full Text Available In this study, time dependent exergy analysis of the Fars Combined Power Plant Cycle has been investigated. Exergy analysis has been used for investigating each part of actual combined cycle by considering irreversibility from Apr 2006 to Oct 2010. Performance analysis has been done for each part by evaluating exergy destruction in each month. By using of exergy analysis, aging of each part has been evaluated respect to time duration. In addition, the rate of lost work for each month has been calculated and variation of this parameter has been considered as a function of aging rate. Finally, effects of exergy destruction of each part have been investigated on exergy destruction of whole cycle. Entire analysis has been done for Unit 3 and 4 of gas turbine cycle which combined by Unit B of steam cycle in Fars Combined Power Plant Cycle located in Fars province in Iran.

  9. Exergy Analysis of a Pilot Parabolic Solar Dish-Stirling System

    Directory of Open Access Journals (Sweden)

    Ehsan Gholamalizadeh

    2017-09-01

    Full Text Available Energy and exergy analyses were carried out for a pilot parabolic solar dish-Stirling System. The system was set up at a site at Kerman City, located in a sunny desert area of Iran. Variations in energy and exergy efficiency were considered during the daytime hours of the average day of each month in a year. A maximum collector energy efficiency and total energy efficiency of 54% and 12.2%, respectively, were predicted in July, while during the period between November and February the efficiency values were extremely low. The maximum collector exergy efficiency was 41.5% in July, while the maximum total exergy efficiency reached 13.2%. The values of energy losses as a percentage of the total losses of the main parts of the system were also reported. Results showed that the major energy and exergy losses occurred in the receiver. The second biggest portion of energy losses occurred in the Stirling engine, while the portion of exergy loss in the concentrator was higher compared to the Stirling engine. Finally, the performance of the Kerman pilot was compared to that of the EuroDish project.

  10. Exergy analysis of integrated waste management in the recovery and recycling of used cooking oils.

    Science.gov (United States)

    Talens Peiró, Laura; Villalba Méndez, Gara; Gabarrell i Durany, Xavier

    2008-07-01

    Used cooking oil (UCO) is a domestic waste generated daily by food industries, restaurants, and households. It is estimated that in Europe 5 kg of UCO are generated per inhabitant, totalling 2.5 million metric tons per year. Recovering UCO for the production of biodiesel offers a way of minimizing and avoiding this waste and related pollution. An exergy analysis of the integrated waste management (IWM) scheme for UCO is used to evaluate such a possibility by accounting for inputs and outputs in each stage, calculating the exergy loss and the resource input and quantifying the possible improvements. The IWM includes the collection, pretreatment, and delivery of UCO and the production of biodiesel. The results show that the greatest exergy loss occurs during the transport stages (57%). Such exergy loss can be minimized to 20% by exploiting the full capacity of collecting vans and using biodiesel in the transport stages. Further, the cumulative exergy consumption helps study how the exergy consumption of biodiesel can be further reduced by using methanol obtained from biogas in the transesterification stage. Finally, the paper discusses how increasing the collection of UCO helps minimize uncontrolled used oil disposal and consequently provides a sustainable process for biodiesel production.

  11. Energy and exergy utilization efficiencies in the Japanese residential/commercial sectors

    International Nuclear Information System (INIS)

    Kondo, Kumiko

    2009-01-01

    Unlike the manufacturing sector, the residential/commercial sectors of Japan struggle to meet their environmental requirements. For instance, their CO 2 emission levels have increased tremendously since 1990. This research estimates energy and 'exergy (available energy)' efficiencies in Japan's residential/commercial sectors during the period 1990-2006. Since an exergy analysis reveals 'available energy losses', it is an effective tool to achieve sustainable societies. The primary objective of this paper is to examine the potential for advancing the 'true' energy efficiency in Japan's residential/commercial sectors-by observing energy and exergy efficiency disparities. The results show large differences between the overall energy and exergy efficiencies in the residential (60.12%, 6.33%)/commercial sectors (51.78%, 5.74%) in 2006. This implies great potential for energy savings in both sectors. Furthermore, this research suggests that the residential sector may face more difficulties than the commercial sector, although the latter appears to be less energy-efficient, according to recent statistics. This is because the disparity between energy and exergy efficiencies has expanded in the residential sector since 2000. This study illustrates the importance of exergy analyses in promoting sustainable energy policies and new adaptation strategies.

  12. Exergy analysis, parametric analysis and optimization for a novel combined power and ejector refrigeration cycle

    International Nuclear Information System (INIS)

    Dai Yiping; Wang Jiangfeng; Gao Lin

    2009-01-01

    A new combined power and refrigeration cycle is proposed, which combines the Rankine cycle and the ejector refrigeration cycle. This combined cycle produces both power output and refrigeration output simultaneously. It can be driven by the flue gas of gas turbine or engine, solar energy, geothermal energy and industrial waste heats. An exergy analysis is performed to guide the thermodynamic improvement for this cycle. And a parametric analysis is conducted to evaluate the effects of the key thermodynamic parameters on the performance of the combined cycle. In addition, a parameter optimization is achieved by means of genetic algorithm to reach the maximum exergy efficiency. The results show that the biggest exergy loss due to the irreversibility occurs in heat addition processes, and the ejector causes the next largest exergy loss. It is also shown that the turbine inlet pressure, the turbine back pressure, the condenser temperature and the evaporator temperature have significant effects on the turbine power output, refrigeration output and exergy efficiency of the combined cycle. The optimized exergy efficiency is 27.10% under the given condition.

  13. Extended exergy concept to facilitate designing and optimization of frequency-dependent direct energy conversion systems

    International Nuclear Information System (INIS)

    Wijewardane, S.; Goswami, Yogi

    2014-01-01

    Highlights: • Proved exergy method is not adequate to optimize frequency-dependent energy conversion. • Exergy concept is modified to facilitate the thermoeconomic optimization of photocell. • The exergy of arbitrary radiation is used for a practical purpose. • The utility of the concept is illustrated using pragmatic examples. - Abstract: Providing the radiation within the acceptable (responsive) frequency range(s) is a common method to increase the efficiency of the frequency-dependent energy conversion systems, such as photovoltaic and nano-scale rectenna. Appropriately designed auxiliary items such as spectrally selective thermal emitters, optical filters, and lenses are used for this purpose. However any energy conversion method that utilizes auxiliary components to increase the efficiency of a system has to justify the potential cost incurred by those auxiliary components through the economic gain emerging from the increased system efficiency. Therefore much effort should be devoted to design innovative systems, effectively integrating the auxiliary items and to optimize the system with economic considerations. Exergy is the widely used method to design and optimize conventional energy conversion systems. Although the exergy concept is used to analyze photovoltaic systems, it has not been used effectively to design and optimize such systems. In this manuscript, we present a modified exergy method in order to effectively design and economically optimize frequency-dependent energy conversion systems. Also, we illustrate the utility of this concept using examples of thermophotovoltaic, Photovoltaic/Thermal and concentrated solar photovoltaic