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Sample records for thermodynamic power cycles

  1. Closed power cycles thermodynamic fundamentals and applications

    CERN Document Server

    Invernizzi, Costante Mario

    2013-01-01

    With the growing attention to the exploitation of renewable energies and heat recovery from industrial processes, the traditional steam and gas cycles are showing themselves often inadequate. The inadequacy is due to the great assortment of the required sizes power and of the large kind of heat sources. Closed Power Cycles: Thermodynamic Fundamentals and Applications offers an organized discussion about the strong interaction between working fluids, the thermodynamic behavior of the cycle using them and the technological design aspects of the machines. A precise treatment of thermal engines op

  2. Finite time thermodynamics of power and refrigeration cycles

    CERN Document Server

    Kaushik, Shubhash C; Kumar, Pramod

    2017-01-01

    This book addresses the concept and applications of Finite Time Thermodynamics to various thermal energy conversion systems including heat engines, heat pumps, and refrigeration and air-conditioning systems. The book is the first of its kind, presenting detailed analytical formulations for the design and optimisation of various power producing and cooling cycles including but not limited to: • Vapour power cycles • Gas power cycles • Vapour compression cycles • Vapour absorption cycles • Rankine cycle coupled refrigeration systems Further, the book addresses the thermoeconomic analysis for the optimisation of thermal cycles, an important field of study in the present age and which is characterised by multi-objective optimization regarding energy, ecology, the environment and economics. Lastly, the book provides the readers with key techniques associated with Finite Time Thermodynamics, allowing them to understand the relevance of irreversibilitie s associated with real processes and the scientific r...

  3. Second Law Of Thermodynamics Analysis Of Triple Cycle Power Plant

    Directory of Open Access Journals (Sweden)

    Matheus M. Dwinanto

    2012-11-01

    Full Text Available Triple cycle power plant with methane as a fuel has been analyzed on the basis of second law of thermodynamics.In this model, ideal Brayton cycle is selected as a topping cycle as it gives higher efficiency at lower pressure ratio comparedintercooler and reheat cycle. In trilple cycle the bottoming cycles are steam Rankine and organic Rankine cycle. Ammoniahas suitable working properties like critical temperature, boiling temperature, etc. Steam cycle consists of a deaerator andreheater. The bottoming ammonia cycle is a ideal Rankine cycle. Single pressure heat recovery steam and ammoniagenerators are selected for simplification of the analysis. The effects of pressure ratio and maximum temperature which aretaken as important parameters regarding the triple cycle are discussed on performance and exergetic losses. On the otherhand, the efficiency of the triple cycle can be raised, especially in the application of recovering low enthalpy content wasteheat. Therefore, by properly combining with a steam Rankine cycle, the ammonia Rankine cycle is expected to efficientlyutilize residual yet available energy to an optimal extent. The arrangement of multiple cycles is compared with combinedcycle having the same sink conditions. The parallel type of arrangement of bottoming cycle is selected due to increasedperformance.

  4. Thermodynamic performance optimization of a combined power/cooling cycle

    International Nuclear Information System (INIS)

    Pouraghaie, M.; Atashkari, K.; Besarati, S.M.; Nariman-zadeh, N.

    2010-01-01

    A combined thermal power and cooling cycle has already been proposed in which thermal energy is used to produce work and to generate a sub-ambient temperature stream that is suitable for cooling applications. The cycle uses ammonia-water mixture as working fluid and is a combination of a Rankine cycle and absorption cycle. The very high ammonia vapor concentration, exiting turbine under certain operating conditions, can provide power output as well as refrigeration. In this paper, the goal is to employ multi-objective algorithms for Pareto approach optimization of thermodynamic performance of the cycle. It has been carried out by varying the selected design variables, namely, turbine inlet pressure (P h ), superheater temperature (T superheat ) and condenser temperature (T condensor ). The important conflicting thermodynamic objective functions that have been considered in this study are turbine work (w T ), cooling capacity (q cool ) and thermal efficiency (η th ) of the cycle. It is shown that some interesting and important relationships among optimal objective functions and decision variables involved in the combined cycle can be discovered consequently. Such important relationships as useful optimal design principles would have not been obtained without the use of a multi-objective optimization approach.

  5. Thermodynamic Analysis of a Supercritical Mercury Power Cycle

    International Nuclear Information System (INIS)

    Roberts, A.S. Jr.

    1969-04-01

    An heat engine is considered which employs supercritical mercury as the working fluid and a magnetohydrodynamic (MHD) generator for thermal to electrical energy conversion. The main thrust of the paper is power cycle thermodynamics, where constraints are imposed by utilizing a MHD generator operating between supercritical, electrically conducting states of the working fluid; and, pump work is accomplished with liquid mercury. The temperature range is approximately 300 to 2200 K and system pressure is > 1,500 atm. Equilibrium and transport properties are carefully considered since these are known to vary radically in the vicinity of the critical point, which is found near the supercritical states of interest. A maximum gross plant efficiency is 20% with a regenerator effectiveness of 90% and greater, a cycle pressure ratio of two, and with highly efficient pump and generator. Certain specified cycle irreversibilities and others such as heat losses and heat exchanger pressure drops, which are not accounted for explicitly, reduce the gross plant efficiency to a few per cent. Experimental efforts aimed at practical application of the power cycle are discouraged by the marginal thermodynamic performance predicted by this study, unless such applications are insensitive to gross cycle efficiency

  6. Thermodynamic Analysis of a Supercritical Mercury Power Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Jr, A S

    1969-04-15

    An heat engine is considered which employs supercritical mercury as the working fluid and a magnetohydrodynamic (MHD) generator for thermal to electrical energy conversion. The main thrust of the paper is power cycle thermodynamics, where constraints are imposed by utilizing a MHD generator operating between supercritical, electrically conducting states of the working fluid; and, pump work is accomplished with liquid mercury. The temperature range is approximately 300 to 2200 K and system pressure is > 1,500 atm. Equilibrium and transport properties are carefully considered since these are known to vary radically in the vicinity of the critical point, which is found near the supercritical states of interest. A maximum gross plant efficiency is 20% with a regenerator effectiveness of 90% and greater, a cycle pressure ratio of two, and with highly efficient pump and generator. Certain specified cycle irreversibilities and others such as heat losses and heat exchanger pressure drops, which are not accounted for explicitly, reduce the gross plant efficiency to a few per cent. Experimental efforts aimed at practical application of the power cycle are discouraged by the marginal thermodynamic performance predicted by this study, unless such applications are insensitive to gross cycle efficiency.

  7. A brief review study of various thermodynamic cycles for high temperature power generation systems

    International Nuclear Information System (INIS)

    Yu, Si-Cong; Chen, Lin; Zhao, Yan; Li, Hong-Xu; Zhang, Xin-Rong

    2015-01-01

    Highlights: • Various high temperature power generation cycles for are reviewed and analyzed. • The operating temperature is higher than 700 K for high temperature power systems. • Thermodynamic cycle model study and working fluid choices are discussed. • Characteristics and future developments of high temperature cycles are presented and compared. - Abstract: This paper presents a review of the previous studies and papers about various thermodynamic cycles working for high temperature power generation procedures, in these cycles the highest temperature is not lower than 700 K. Thermodynamic cycles that working for power generation are divided into two broad categories, thermodynamic cycle model study and working fluid analysis. Thermodynamic cycle contains the simple cycle model and the complex cycle model, emphasis has been given on the complex thermodynamic cycles due to their high thermal efficiencies. Working fluids used for high temperature thermodynamic cycles is a dense gas rather than a liquid. A suitable thermodynamic cycle is crucial for effectively power generation especially under the condition of high temperature. The main purpose is to find out the characteristics of various thermodynamic cycles when they are working in the high temperature region for power generation. As this study shows, combined cycles with both renewable and nonrenewable energies as the heat source can show good performance

  8. Thermodynamic and economic analysis and optimization of power cycles for a medium temperature geothermal resource

    International Nuclear Information System (INIS)

    Coskun, Ahmet; Bolatturk, Ali; Kanoglu, Mehmet

    2014-01-01

    Highlights: • We conduct the thermodynamic and economic analysis of various geothermal power cycles. • The optimization process was performed to minimize the exergy losses. • Kalina cycle is a new technology compared to flash and binary cycles. • It is shown that Kalina cycle presents a viable choice for both thermodynamically and economically. - Abstract: Geothermal power generation technologies are well established and there are numerous power plants operating worldwide. Turkey is rich in geothermal resources while most resources are not exploited for power production. In this study, we consider geothermal resources in Kutahya–Simav region having geothermal water at a temperature suitable for power generation. The study is aimed to yield the method of the most effective use of the geothermal resource and a rational thermodynamic and economic comparison of various cycles for a given resource. The cycles considered include double-flash, binary, combined flash/binary, and Kalina cycle. The selected cycles are optimized for the turbine inlet pressure that would generate maximum power output and energy and exergy efficiencies. The distribution of exergy in plant components and processes are shown using tables. Maximum first law efficiencies vary between 6.9% and 10.6% while the second law efficiencies vary between 38.5% and 59.3% depending on the cycle considered. The maximum power output, the first law, and the second law efficiencies are obtained for Kalina cycle followed by combined cycle and binary cycle. An economic analysis of four cycles considered indicates that the cost of producing a unit amount of electricity is 0.0116 $/kW h for double flash and Kalina cycles, 0.0165 $/kW h for combined cycle and 0.0202 $/kW h for binary cycle. Consequently, the payback period is 5.8 years for double flash and Kalina cycles while it is 8.3 years for combined cycle and 9 years for binary cycle

  9. Output power analyses for the thermodynamic cycles of thermal power plants

    International Nuclear Information System (INIS)

    Sun Chen; Cheng Xue-Tao; Liang Xin-Gang

    2014-01-01

    Thermal power plant is one of the important thermodynamic devices, which is very common in all kinds of power generation systems. In this paper, we use a new concept, entransy loss, as well as exergy destruction, to analyze the single reheating Rankine cycle unit and the single stage steam extraction regenerative Rankine cycle unit in power plants. This is the first time that the concept of entransy loss is applied to the analysis of the power plant Rankine cycles with reheating and steam extraction regeneration. In order to obtain the maximum output power, the operating conditions under variant vapor mass flow rates are optimized numerically, as well as the combustion temperatures and the off-design flow rates of the flue gas. The relationship between the output power and the exergy destruction rate and that between the output power and the entransy loss rate are discussed. It is found that both the minimum exergy destruction rate and the maximum entransy loss rate lead to the maximum output power when the combustion temperature and heat capacity flow rate of the flue gas are prescribed. Unlike the minimum exergy destruction rate, the maximum entransy loss rate is related to the maximum output power when the highest temperature and heat capacity flow rate of the flue gas are not prescribed. (general)

  10. THERMODYNAMIC ANALYSIS AND SIMULATION OF A NEW COMBINED POWER AND REFRIGERATION CYCLE USING ARTIFICIAL NEURAL NETWORK

    Directory of Open Access Journals (Sweden)

    Hossein Rezvantalab

    2011-01-01

    Full Text Available In this study, a new combined power and refrigeration cycle is proposed, which combines the Rankine and absorption refrigeration cycles. Using a binary ammonia-water mixture as the working fluid, this combined cycle produces both power and refrigeration output simultaneously by employing only one external heat source. In order to achieve the highest possible exergy efficiency, a secondary turbine is inserted to expand the hot weak solution leaving the boiler. Moreover, an artificial neural network (ANN is used to simulate the thermodynamic properties and the relationship between the input thermodynamic variables on the cycle performance. It is shown that turbine inlet pressure, as well as heat source and refrigeration temperatures have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. In addition, the results of ANN are in excellent agreement with the mathematical simulation and cover a wider range for evaluation of cycle performance.

  11. Performance comparison of different thermodynamic cycles for an innovative central receiver solar power plant

    Science.gov (United States)

    Reyes-Belmonte, Miguel A.; Sebastián, Andrés; González-Aguilar, José; Romero, Manuel

    2017-06-01

    The potential of using different thermodynamic cycles coupled to a solar tower central receiver that uses a novel heat transfer fluid is analyzed. The new fluid, named as DPS, is a dense suspension of solid particles aerated through a tubular receiver used to convert concentrated solar energy into thermal power. This novel fluid allows reaching high temperatures at the solar receiver what opens a wide range of possibilities for power cycle selection. This work has been focused into the assessment of power plant performance using conventional, but optimized cycles but also novel thermodynamic concepts. Cases studied are ranging from subcritical steam Rankine cycle; open regenerative Brayton air configurations at medium and high temperature; combined cycle; closed regenerative Brayton helium scheme and closed recompression supercritical carbon dioxide Brayton cycle. Power cycle diagrams and working conditions for design point are compared amongst the studied cases for a common reference thermal power of 57 MWth reaching the central cavity receiver. It has been found that Brayton air cycle working at high temperature or using supercritical carbon dioxide are the most promising solutions in terms of efficiency conversion for the power block of future generation by means of concentrated solar power plants.

  12. Thermodynamic and economic analysis on geothermal integrated combined-cycle power plants

    International Nuclear Information System (INIS)

    Bettocchi, R.; Cantore, G.; Negri di Montenegro, G.; Gadda, E.

    1992-01-01

    This paper considers geothermal integrated power plants obtained matching a geothermal plant with, a two pressure level combined plant. The purpose of the paper is the evaluation of thermodynamic and economic aspects on geothermal integrated combined-cycle power plant and a comparison with conventional solutions. The results show that the integrated combined plant power is greater than the sum of combined cycle and geothermal plant powers considered separately and that the integrated plant can offer economic benefits reaching the 16% of the total capital required

  13. Parametric-based thermodynamic analysis of organic Rankine cycle as bottoming cycle for combined-cycle power plant

    International Nuclear Information System (INIS)

    Qureshi, S.; Memon, A.G.; Abbasi, A.F.

    2017-01-01

    In Pakistan, the thermal efficiency of the power plants is low because of a huge share of fuel energy is dumped into the atmosphere as waste heat. The ORC (Organic Rankine Cycle) has been revealed as one of the promising technologies to recover waste heat to enhance the thermal efficiency of the power plant. In current work, ORC is proposed as a second bottoming cycle for existing CCPP (Combined Cycle Power Plant). In order to assess the efficiency of the plant, a thermodynamic model is developed in the ESS (Engineering Equation Solver) software. The developed model is used for parametric analysis to assess the effects of various operating parameters on the system performance. The analysis of results shows that the integration of ORC system with existing CCPP system enhances the overall power output in the range of 150.5-154.58 MW with 0.24-5% enhancement in the efficiency depending on the operating conditions. During the parametric analysis of ORC, it is observed that inlet pressure of the turbine shows a significant effect on the performance of the system as compared to other operating parameters. (author)

  14. Thermodynamic modelling of a recompression CO_2 power cycle for low temperature waste heat recovery

    International Nuclear Information System (INIS)

    Banik, Shubham; Ray, Satyaki; De, Sudipta

    2016-01-01

    Highlights: • Thermodynamic model for recompression T-CO_2 is developed. • Energetic and exergetic analysis compared with S-CO_2 and Reg. Brayton cycle. • Maximum efficiency of 13.6% is obtained for T-CO_2 cycle. • Optimum recompression ratio of 0.48 is obtained for minimum irreversibility. • Reg. Brayton has better efficiency, T-CO_2 offers minimum irreversibility. - Abstract: Due to the rising prices of conventional fossil fuels, increasing the overall thermal efficiency of a power plant is essential. One way of doing this is waste heat recovery. This recovery is most difficult for low temperature waste heat, below 240 °C, which also covers majority of the waste heat source. Carbon dioxide, with its low critical temperature and pressure, offers an advantage over ozone-depleting refrigerants used in Organic Rankine Cycles (ORCs) and hence is most suitable for the purpose. This paper introduces parametric optimization of a transcritical carbon dioxide (T-CO_2) power cycle which recompresses part of the total mass flow of working fluid before entering the precooler, thereby showing potential for higher cycle efficiency. Thermodynamic model for a recompression T-CO_2 power cycle has been developed with waste heat source of 2000 kW and at a temperature of 200 °C. Results obtained from this model are analysed to estimate effects on energetic and exergetic performances of the power cycle with varying pressure and mass recompression ratio. Higher pressure ratio always improves thermodynamic performance of the cycle – both energetic and exergetic. Higher recompression ratio also increases exergetic efficiency of the cycle. However, it increases energy efficiency, only if precooler inlet temperature remains constant. Maximum thermal efficiency of the T-CO_2 cycle with a recompression ratio of 0.26 has been found to be 13.6%. To minimize total irreversibility of the cycle, an optimum ratio of 0.48 was found to be suitable.

  15. Thermodynamic analyses and optimization of a recompression N2O Brayton power cycle

    International Nuclear Information System (INIS)

    Sarkar, Jahar

    2010-01-01

    Thermodynamic analyses and simultaneous optimizations of cycle pressure ratio and flow split fraction to get maximum efficiency of N 2 O recompression Brayton cycle have been performed to study the effects of various operating conditions and component performances. The energetic as well as exergetic performance comparison with its counterpart recompression CO 2 cycle is presented as well. Optimization shows that the optimum minimum cycle pressure is close to pseudo-critical pressure for supercritical cycle, whereas saturation pressure corresponding to minimum cycle temperature for condensation cycle. Results show that the maximum thermal efficiency increases with decrease in minimum cycle temperature and increase in both maximum cycle pressure and temperature. Influence of turbine performance on cycle efficiency is more compared to that of compressors, HTR (high temperature recuperator) and LTR (low temperature recuperator). Comparison shows that N 2 O gives better thermal efficiency (maximum deviation of 1.2%) as well as second law efficiency compared to CO 2 for studied operating conditions. Component wise irreversibility distribution shows the similar trends for both working fluids. Present study reveals that N 2 O is a potential option for the recompression power cycle.

  16. Thermodynamic analysis of heat recovery steam generator in combined cycle power plant

    Directory of Open Access Journals (Sweden)

    Ravi Kumar Naradasu

    2007-01-01

    Full Text Available Combined cycle power plants play an important role in the present energy sector. The main challenge in designing a combined cycle power plant is proper utilization of gas turbine exhaust heat in the steam cycle in order to achieve optimum steam turbine output. Most of the combined cycle developers focused on the gas turbine output and neglected the role of the heat recovery steam generator which strongly affects the overall performance of the combined cycle power plant. The present paper is aimed at optimal utilization of the flue gas recovery heat with different heat recovery steam generator configurations of single pressure and dual pressure. The combined cycle efficiency with different heat recovery steam generator configurations have been analyzed parametrically by using first law and second law of thermodynamics. It is observed that in the dual cycle high pressure steam turbine pressure must be high and low pressure steam turbine pressure must be low for better heat recovery from heat recovery steam generator.

  17. Effects of ammonia concentration on the thermodynamic performances of ammonia–water based power cycles

    International Nuclear Information System (INIS)

    Kim, Kyoung Hoon; Han, Chul Ho; Kim, Kyoungjin

    2012-01-01

    The power generation systems using a binary working fluid such as ammonia–water mixture are proven to be the feasible method for utilizing a low-temperature waste heat source. In this work, ammonia–water based Rankine (AWR) regenerative Rankine (AWRR) power generation cycles are comparatively analyzed by investigating the effects of ammonia mass concentration in the working fluid on the thermodynamic performances of systems. Temperature distributions of fluid streams in the heat exchanging devices are closely examined at different levels of ammonia concentration and they might be the most important design consideration in optimizing the power systems using a binary working fluid. The analysis shows that the lower limit of workable ammonia concentration decreases with increasing turbine inlet pressure. Results also show that both the thermal and exergy efficiencies of AWRR system are generally better than those of AWR system, and can have peaks at the minimum allowable ammonia concentrations in the working range of system operation.

  18. Investigation of thermodynamic performances for two solar-biomass hybrid combined cycle power generation systems

    International Nuclear Information System (INIS)

    Liu, Qibin; Bai, Zhang; Wang, Xiaohe; Lei, Jing; Jin, Hongguang

    2016-01-01

    Highlights: • Two solar-biomass hybrid combined cycle power generation systems are proposed. • The characters of the two proposed systems are compared. • The on-design and off-design properties of the system are numerically investigated. • The favorable performances of thermochemical hybrid routine are validated. - Abstract: Two solar-biomass hybrid combined cycle power generation systems are proposed in this work. The first system employs the thermochemical hybrid routine, in which the biomass gasification is driven by the concentrated solar energy, and the gasified syngas as a solar fuel is utilized in a combined cycle for generating power. The second system adopts the thermal integration concept, and the solar energy is directly used to heat the compressed air in the topping Brayton cycle. The thermodynamic performances of the developed systems are investigated under the on-design and off-design conditions. The advantages of the hybrid utilization technical mode are demonstrated. The solar energy can be converted and stored into the chemical fuel by the solar-biomass gasification, with the net solar-to-fuel efficiency of 61.23% and the net solar share of 19.01% under the specific gasification temperature of 1150 K. Meanwhile, the proposed system with the solar thermochemical routine shows more favorable behaviors, the annual system overall energy efficiency and the solar-to-electric efficiency reach to 29.36% and 18.49%, while the with thermal integration concept of 28.03% and 15.13%, respectively. The comparison work introduces a promising approach for the efficient utilization of the abundant solar and biomass resources in the western China, and realizes the mitigation of CO_2 emission.

  19. Thermodynamic analysis of a binary power cycle for different EGS geofluid temperatures

    International Nuclear Information System (INIS)

    Zhang Fuzen; Jiang Peixe

    2012-01-01

    Enhanced Geothermal Systems show promise for meeting growing energy demands. The Organic Rankine Cycle (ORC) can be used to convert low and medium-temperature geothermal energy to electricity, but the working fluid must be carefully selected for the ORC system design. This paper compares the system performance using R134a, isobutane, R245fa and isopentane for four typical geofluid temperatures below 200 °C. Three type (subcritical, superheated and transcritical) power generation cycles and two heat transfer control models (total heat control model and vaporization control model) are used for different EGS source temperatures and working fluids. This paper presents a basic analysis method to select the most suitable working fluid and to optimize the operating and design parameters for a given EGS resource based on the thermodynamics. - Highlights: ► We present a method to selecting working fluids for EGS resources. ► Working fluids with critical temperatures near geofluid temperature is priority. ► Operating conditions requiring use of total heat control model give good behave. ► Transcritical cycle is good choice.

  20. Thermodynamic Analysis of a Rankine Cycle Powered Vapor Compression Ice Maker Using Solar Energy

    Directory of Open Access Journals (Sweden)

    Bing Hu

    2014-01-01

    Full Text Available To develop the organic Rankine-vapor compression ice maker driven by solar energy, a thermodynamic model was developed and the effects of generation temperature, condensation temperature, and working fluid types on the system performance were analyzed. The results show that the cooling power per square meter collector and ice production per square meter collector per day depend largely on generation temperature and condensation temperature and they increase firstly and then decrease with increasing generation temperature. For every working fluid there is an optimal generation temperature at which organic Rankine efficiency achieves the maximum value. The cooling power per square meter collector and ice production per square meter collector per day are, respectively, 126.44 W m−2 and 7.61 kg m−2 day−1 at the generation temperature of 140°C for working fluid of R245fa, which demonstrates the feasibility of organic Rankine cycle powered vapor compression ice maker.

  1. Thermodynamic analysis and comparison between CO_2 transcritical power cycles and R245fa organic Rankine cycles for low grade heat to power energy conversion

    International Nuclear Information System (INIS)

    Li, L.; Ge, Y.T.; Luo, X.; Tassou, S.A.

    2016-01-01

    Highlights: • CO_2 is a promising working fluid to be applied in low-grade power generation systems. • Thermodynamic models of CO_2 transcritical power cycles (T-CO_2) and R245fa ORC were developed. • Energy and exergy analyses were carried out for T-CO_2 and R245fa ORC systems. • Optimal system designs are existed for both T-CO_2 and R245fa ORC systems. - Abstract: In this paper, a theoretical study is conducted to investigate and compare the performance of CO_2 transcritical power cycles (T-CO_2) and R245fa organic Rankine cycles (ORCs) using low-grade thermal energy to produce useful shaft or electrical power. Each power cycle consists of typical Rankine cycle components, such as a working fluid pump, gas generator or evaporator, turbine with electricity generator, air cooled condenser and recuperator (internal heat exchanger). The thermodynamic models of both cycles have been developed and are applied to calculate and compare the cycle thermal and exergy efficiencies at different operating conditions and control strategies. The simulation results show that the system performances for both cycles vary with different operating conditions. When the heat source (waste heat) temperature increases from 120 °C to 260 °C and heat sink (cooling air) temperature is reduced from 20 °C to 0 °C, both thermal efficiencies of R245fa ORC and T-CO_2 with recuperator can significantly increase. On the other hand, R245fa ORC and T-CO_2 exergy efficiencies increase with lower heat sink temperatures and generally decrease with higher heat source temperatures. In addition, with the same operating conditions and heat transfer assumptions, the thermal and exergy efficiencies of R245fa ORCs are both slightly higher than those of T-CO_2. However, the efficiencies of both cycles can be enhanced by installing a recuperator in each system at specified operating conditions. Ultimately, optimal operating states can be predicted, with particular focus on the working fluid expander

  2. Advanced gas turbine cycles a brief review of power generation thermodynamics

    CERN Document Server

    Horlock, JH

    2003-01-01

    Primarily this book describes the thermodynamics of gas turbine cycles. The search for high gas turbine efficiency has produced many variations on the simple ""open circuit"" plant, involving the use of heat exchangers, reheating and intercooling, water and steam injection, cogeneration and combined cycle plants. These are described fully in the text. A review of recent proposals for a number of novel gas turbine cycles is also included. In the past few years work has been directed towards developing gas turbines which produce less carbon dioxide, or plants from which the CO2 can be d

  3. Evaluation of the maximized power of a regenerative endoreversible Stirling cycle using the thermodynamic analysis

    International Nuclear Information System (INIS)

    Ahmadi, Mohammad H.; Mohammadi, Amir H.; Dehghani, Saeed

    2013-01-01

    Highlights: • The optimal power of an endoreversible Stirling cycle is investigated. • In the endoreversible cycle, external heat transfer processes are considered irreversible. • Optimal temperature of the heat source leading to a maximum power for the cycle is detained. • Effect of design parameters on the power and its corresponding thermal efficiency is studied. - Abstract: In this communication, the optimal power of an endoreversible Stirling cycle with perfect regeneration is investigated. In the endoreversible cycle, external heat transfer processes are irreversible. Optimal temperature of the heat source leading to a maximum power for the cycle is detained. Moreover, effect of design parameters of the Stirling engine on the maximized power of the engine and its corresponding thermal efficiency is studied

  4. A low pressure thermodynamic cycle for electric power generation without mechanical compressor

    International Nuclear Information System (INIS)

    Proto, G.; Lenti, R.

    1996-01-01

    According to the 2 nd thermodynamic law there is no compulsion to have an expansion from high pressure level to atmospheric pressure, the only reason relying upon the minimization of the plant volumetry which is just one of the overall cost parameters. A thermodynamic cycle without rotating machinery does exist in avionic applications like the RAMJET, in which air flowing at supersonic speed is compressed in a convergent duct before being heated in the combustion chamber and then expanded to a much higher MACH number. The concept discussed here, however, is referred to a physical principle of different nature. In fact the inlet air flow is quasi static, while the propelling kinetic energy is the residual energy following the gas combustion, expansion, cooling in Supersonic Flow and ultimately its fluidic compression in a convergent duct. The concept theoretically relies upon the so called 'Simple T 0 change' transformation, according to which, in a Supersonic Flow at constant cross section and without mechanical dissipation, a decrease in the gas stagnation temperature (T 0 ) will turn into an increase of its stagnation pressure. The paper discusses the feasibility of such a process, focusing on a specific conceptual application to a subatmospheric pressure, high temperature Brayton cycle getting to the conclusion that, even with the materials technology limitations, there is the potential for significant improvement of the actual thermodynamic cycle efficiency. (author). 6 figs.,1 tab., 2 refs

  5. 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.

  6. A strategy for the economic optimization of combined cycle gas turbine power plants by taking advantage of useful thermodynamic relationships

    International Nuclear Information System (INIS)

    Godoy, E.; Benz, S.J.; Scenna, N.J.

    2011-01-01

    Optimal combined cycle gas turbine power plants characterized by minimum specific annual cost values are here determined for wide ranges of market conditions as given by the relative weights of capital investment and operative costs, by means of a non-linear mathematical programming model. On the other hand, as the technical optimization allows identifying trends in the system behavior and unveiling optimization opportunities, selected functional relationships are obtained as the thermodynamic optimal values of the decision variables are systematically linked to the ratio between the total heat transfer area and the net power production (here named as specific transfer area). A strategy for simplifying the resolution of the rigorous economic optimization problem of power plants is proposed based on the economic optima distinctive characteristics which describe the behavior of the decision variables of the power plant on its optima. Such approach results in a novel mathematical formulation shaped as a system of non-linear equations and additional constraints that is able to easily provide accurate estimations of the optimal values of the power plant design and operative variables. Research highlights: → We achieve relationships between power plants' economic and thermodynamic optima. → We achieve functionalities among thermodynamic optimal values of decision variables. → The rigorous optimization problem is reduced to a non-linear equations system. → Accurate estimations of power plants' design and operative variables are obtained.

  7. Families of optimal thermodynamic solutions for combined cycle gas turbine (CCGT) power plants

    International Nuclear Information System (INIS)

    Godoy, E.; Scenna, N.J.; Benz, S.J.

    2010-01-01

    Optimal designs of a CCGT power plant characterized by maximum second law efficiency values are determined for a wide range of power demands and different values of the available heat transfer area. These thermodynamic optimal solutions are found within a feasible operation region by means of a non-linear mathematical programming (NLP) model, where decision variables (i.e. transfer areas, power production, mass flow rates, temperatures and pressures) can vary freely. Technical relationships among them are used to systematize optimal values of design and operative variables of a CCGT power plant into optimal solution sets, named here as optimal solution families. From an operative and design point of view, the families of optimal solutions let knowing in advance optimal values of the CCGT variables when facing changes of power demand or adjusting the design to an available heat transfer area.

  8. Theoretical thermodynamic analysis of Rankine power cycle with thermal driven pump

    International Nuclear Information System (INIS)

    Lakew, Amlaku Abie; Bolland, Olav; Ladam, Yves

    2011-01-01

    Highlights: → The work is focused on theoretical aspects of thermal driven pump (TDP) Rankine cycle. → The mechanical pump is replaced by thermal driven pump. → Important parameters of thermal driven pump Rankine cycle are investigated. → TDP Rankine cycle produce more power but it requires additional low grade heat. - Abstract: A new approach to improve the performance of supercritical carbon dioxide Rankine cycle which uses low temperature heat source is presented. The mechanical pump in conventional supercritical carbon dioxide Rankine cycle is replaced by thermal driven pump. The concept of thermal driven pump is to increase the pressure of a fluid in a closed container by supplying heat. A low grade heat source is used to increase the pressure of the fluid instead of a mechanical pump, this increase the net power output and avoid the need for mechanical pump which requires regular maintenance and operational cost. The thermal driven pump considered is a shell and tube heat exchanger where the working fluid is contained in the tube, a tube diameter of 5 mm is chosen to reduce the heating time. The net power output of the Rankine cycle with thermal driven pump is compared to that of Rankine cycle with mechanical pump and it is observed that the net power output is higher when low grade thermal energy is used to pressurize the working fluid. The thermal driven pump consumes additional heat at low temperature (60 o C) to pressurize the working fluid.

  9. Thermodynamic analysis of a combined-cycle solar thermal power plant with manganese oxide-based thermochemical energy storage

    Directory of Open Access Journals (Sweden)

    Lei Qi

    2017-01-01

    Full Text Available We explore the thermodynamic efficiency of a solar-driven combined cycle power system with manganese oxide-based thermochemical energy storage system. Manganese oxide particles are reduced during the day in an oxygen-lean atmosphere obtained with a fluidized-bed reactor at temperatures in the range of 750–1600°C using concentrated solar energy. Reduced hot particles are stored and re-oxidized during night-time to achieve continuous power plant operation. The steady-state mass and energy conservation equations are solved for all system components to calculate the thermodynamic properties and mass flow rates at all state points in the system, taking into account component irreversibilities. The net power block and overall solar-to-electric energy conversion efficiencies, and the required storage volumes for solids and gases in the storage system are predicted. Preliminary results for a system with 100 MW nominal solar power input at a solar concentration ratio of 3000, designed for constant round-the-clock operation with 8 hours of on-sun and 16 hours of off-sun operation and with manganese oxide particles cycled between 750 and 1600°C yield a net power block efficiency of 60.0% and an overall energy conversion efficiency of 41.3%. Required storage tank sizes for the solids are estimated to be approx. 5–6 times smaller than those of state-of-the-art molten salt systems.

  10. Thermodynamic analysis of a combined-cycle solar thermal power plant with manganese oxide-based thermochemical energy storage

    Science.gov (United States)

    Lei, Qi; Bader, Roman; Kreider, Peter; Lovegrove, Keith; Lipiński, Wojciech

    2017-11-01

    We explore the thermodynamic efficiency of a solar-driven combined cycle power system with manganese oxide-based thermochemical energy storage system. Manganese oxide particles are reduced during the day in an oxygen-lean atmosphere obtained with a fluidized-bed reactor at temperatures in the range of 750-1600°C using concentrated solar energy. Reduced hot particles are stored and re-oxidized during night-time to achieve continuous power plant operation. The steady-state mass and energy conservation equations are solved for all system components to calculate the thermodynamic properties and mass flow rates at all state points in the system, taking into account component irreversibilities. The net power block and overall solar-to-electric energy conversion efficiencies, and the required storage volumes for solids and gases in the storage system are predicted. Preliminary results for a system with 100 MW nominal solar power input at a solar concentration ratio of 3000, designed for constant round-the-clock operation with 8 hours of on-sun and 16 hours of off-sun operation and with manganese oxide particles cycled between 750 and 1600°C yield a net power block efficiency of 60.0% and an overall energy conversion efficiency of 41.3%. Required storage tank sizes for the solids are estimated to be approx. 5-6 times smaller than those of state-of-the-art molten salt systems.

  11. 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.

  12. Comprehensive performance analyses and optimization of the irreversible thermodynamic cycle engines (TCE) under maximum power (MP) and maximum power density (MPD) conditions

    International Nuclear Information System (INIS)

    Gonca, Guven; Sahin, Bahri; Ust, Yasin; Parlak, Adnan

    2015-01-01

    This paper presents comprehensive performance analyses and comparisons for air-standard irreversible thermodynamic cycle engines (TCE) based on the power output, power density, thermal efficiency, maximum dimensionless power output (MP), maximum dimensionless power density (MPD) and maximum thermal efficiency (MEF) criteria. Internal irreversibility of the cycles occurred during the irreversible-adiabatic processes is considered by using isentropic efficiencies of compression and expansion processes. The performances of the cycles are obtained by using engine design parameters such as isentropic temperature ratio of the compression process, pressure ratio, stroke ratio, cut-off ratio, Miller cycle ratio, exhaust temperature ratio, cycle temperature ratio and cycle pressure ratio. The effects of engine design parameters on the maximum and optimal performances are investigated. - Highlights: • Performance analyses are conducted for irreversible thermodynamic cycle engines. • Comprehensive computations are performed. • Maximum and optimum performances of the engines are shown. • The effects of design parameters on performance and power density are examined. • The results obtained may be guidelines to the engine designers

  13. The thermodynamic cycle models for geothermal power plants by considering the working fluid characteristic

    Science.gov (United States)

    Mulyana, Cukup; Adiprana, Reza; Saad, Aswad H.; M. Ridwan, H.; Muhammad, Fajar

    2016-02-01

    The scarcity of fossil energy accelerates the development of geothermal power plant in Indonesia. The main issue is how to minimize the energy loss from the geothermal working fluid so that the power generated can be increased. In some of geothermal power plant, the hot water which is resulted from flashing is flown to injection well, and steam out from turbine is condensed in condenser, while the temperature and pressure of the working fluid is still high. The aim of this research is how the waste energy can be re-used as energy source to generate electric power. The step of the research is started by studying the characteristics of geothermal fluid out from the well head. The temperature of fluid varies from 140°C - 250°C, the pressure is more than 7 bar and the fluid phase are liquid, gas, or mixing phase. Dry steam power plant is selected for vapor dominated source, single or multiple flash power plant is used for dominated water with temperature > 225°C, while the binary power plant is used for low temperature of fluid enthalpy, the calculated power of these double and triple flash power plant are 50% of W1+W2. At the last step, the steam out from the turbine of unit 3 with the temperature 150°C is used as a heat source for binary cycle power plant named unit 4, while the hot water from the flasher is used as a heat source for the other binary cycle named unit 5 resulted power W5+W6 or 15% of W1+W2. Using this integrated model the power increased 75% from the original one.

  14. Optimum operating conditions for a combined power and cooling thermodynamic cycle

    International Nuclear Information System (INIS)

    Sadrameli, S.M.; Goswami, D.Y.

    2007-01-01

    The combined production of thermal power and cooling with an ammonia-water based cycle proposed by Goswami is under intensive investigation. In the cycle under consideration, simultaneous cooling output is produced by expanding an ammonia-rich vapor in an expander to sub-ambient temperatures and subsequently heating the cool exhaust. When this mechanism for cooling production is considered in detail, it is apparent that the cooling comes at some expense to work production. To optimize this trade-off, a very specific coefficient-of-performance has been defined. In this paper, the simulation of the cycle was carried out in the process simulator ASPEN Plus. The optimum operating conditions have been found by using the Equation Oriented mode of the simulator and some of the results have been compared with the experimental data obtained from the cycle. The agreement between the two sets proves the accuracy of the optimization results

  15. A thermodynamic analysis of waste heat recovery from reciprocating engine power plants by means of Organic Rankine Cycles

    International Nuclear Information System (INIS)

    Uusitalo, Antti; Honkatukia, Juha; Turunen-Saaresti, Teemu; Larjola, Jaakko

    2014-01-01

    Organic Rankine Cycle (ORC) is a Rankine cycle using organic fluid as the working fluid instead of water and steam. The ORC process is a feasible choice in waste heat recovery applications producing electricity from relatively low-temperature waste heat sources or in applications having a rather low power output. Utilizing waste heat from a large high-efficiency reciprocating engine power plant with ORC processes is studied by means of computations. In addition to exhaust gas heat recovery, this study represents and discusses an idea of directly replacing the charge air cooler (CAC) of a large turbocharged engine with an ORC evaporator to utilize the charge air heat in additional power production. A thermodynamic analysis for ORCs was carried out with working fluids toluene, n-pentane, R245fa and cyclohexane. The effect of different ORC process parameters on the process performance are presented and analyzed in order to investigate the heat recovery potential from the exhaust gas and charge air. A simplified feasibility consideration is included by comparing the ratio of the theoretical heat transfer areas needed and the obtained power output from ORC processes. The greatest potential is related to the exhaust gas heat recovery, but in addition also the lower temperature waste heat streams could be utilized to boost the electrical power of the engine power plant. A case study for a large-scale gas-fired engine was carried out showing that the maximum power increase of 11.4% was obtained from the exhaust gas and 2.4% from the charge air heat. - Highlights: • Waste heat recovery potential of reciprocating engines was studied. • Thermodynamic optimization for ORCs was carried out with different fluids. • The utilization of exhaust gas and charge air heat is presented and discussed. • Simplified economic feasibility study was included in the analysis. • Power increase of 11.4% was obtained from exhaust gas and 2.4% from charge air

  16. Thermodynamic performance assessment of an integrated geothermal powered supercritical regenerative organic Rankine cycle and parabolic trough solar collectors

    International Nuclear Information System (INIS)

    Cakici, Duygu Melek; Erdogan, Anil; Colpan, Can Ozgur

    2017-01-01

    In this study, the thermodynamic performance of an integrated geothermal powered supercritical regenerative organic Rankine cycle (ORC) and parabolic trough solar collectors (PTSC) is assessed. A thermal model based on the principles of thermodynamics (mass, energy, and exergy balances) and heat transfer is first developed for the components of this integrated system. This model gives the performance assessment parameters of the system such as the electrical and exergetic efficiencies, total exergy destruction and loss, productivity lack, fuel depletion ratio, and improvement potential rate. To validate this model, the data of an existing geothermal power plant based on a supercritical ORC and literature data for the PTSC are used. After validation, parametric studies are conducted to assess the effect of some of the important design and operating parameters on the performance of the system. As a result of these studies, it is found that the integration of ORC and PTSC systems increases the net power output but decreases the electrical and exergetic efficiencies of the integrated system. It is also shown that R134a is the most suitable working fluid type for this system; and the PTSCs and air cooled condenser are the main sources of the exergy destructions. - Highlights: • A geothermal power plant integrated with PTSC is investigated. • Different approaches for defining the exergetic efficiency are used. • The PTSCs and ACC are the main sources of the exergy destructions. • R134a gives the highest performance for any number of collectors studied.

  17. Thermodynamics and heat power

    CERN Document Server

    Granet, Irving

    2014-01-01

    Fundamental ConceptsIntroductionThermodynamic SystemsTemperatureForce and MassElementary Kinetic Theory of GasesPressureReviewKey TermsEquations Developed in This ChapterQuestionsProblemsWork, Energy, and HeatIntroductionWorkEnergyInternal EnergyPotential EnergyKinetic EnergyHeatFlow WorkNonflow WorkReviewKey TermsEquations Developed in This ChapterQuestionsProblemsFirst Law of ThermodynamicsIntroductionFirst Law of ThermodynamicsNonflow SystemSteady-Flow SystemApplications of First Law of ThermodynamicsReviewKey TermsEquations Developed in This ChapterQuestionsProblemsThe Second Law of ThermodynamicsIntroductionReversibility-Second Law of ThermodynamicsThe Carnot CycleEntropyReviewKey TermsEquations Developed in This ChapterQuestionsProblemsProperties of Liquids and GasesIntroductionLiquids and VaporsThermodynamic Properties of SteamComputerized PropertiesThermodynamic DiagramsProcessesReviewKey TermsEquations Developed in This ChapterQuestionsProblemsThe Ideal GasIntroductionBasic ConsiderationsSpecific Hea...

  18. Thermodynamic analysis and optimization of a Closed Regenerative Brayton Cycle for nuclear space power systems

    International Nuclear Information System (INIS)

    Ribeiro, Guilherme B.; Braz Filho, Francisco A.; Guimarães, Lamartine N.F.

    2015-01-01

    Nuclear power systems turned to space electric propulsion differ strongly from usual ground-based power systems regarding the importance of overall size and mass. For propulsion power systems, size and mass are essential drivers that should be minimized during conception processes. Considering this aspect, this paper aims the development of a design-based model of a Closed Regenerative Brayton Cycle that applies the thermal conductance of the main components in order to predict the energy conversion performance, allowing its use as a preliminary tool for heat exchanger and radiator panel sizing. The centrifugal-flow turbine and compressor characterizations were achieved using algebraic equations from literature data. A binary mixture of Helium–Xenon with molecular weight of 40 g/mole is applied and the impact of the components sizing in the energy efficiency is evaluated in this paper, including the radiator panel area. Moreover, an optimization analysis based on the final mass of heat the exchangers is performed. - Highlights: • A design-based model of a Closed Brayton Cycle is proposed for nuclear space needs. • Turbomachinery efficiency presented a strong influence on the system efficiency. • Radiator area presented the highest potential to increase the system efficiency. • There is maximum system efficiency for each total mass of heat exchangers. • Size or efficiency optimization was performed by changing heat exchanger proportion.

  19. Thermodynamics of nuclear power systems

    International Nuclear Information System (INIS)

    Anno, J.

    1983-01-01

    The conversion of nuclear energy to useful work follows essentially the same course as the conversion of thermal energy from fossil fuel to work. The thermal energy released in the reactor core is first transferred to the primary coolant which then generally transfers its heat to a secondary fluid. The secondary fluid serves as the working fluid in a heat engine. In this chapter the authors briefly examine the thermodynamic principles governing the operation of such engines, the major thermodynamic cycles used, and their application to nuclear power plants

  20. Thermodynamics of nuclear power systems

    International Nuclear Information System (INIS)

    Anno, J.

    1977-01-01

    The conversion of nuclear energy to useful work follows essentially the same course as the conversion of thermal energy from fossil fuel to work. The thermal energy released in the reactor core is first transferred to the primary coolant which then generally transfers its heat to a secondary fluid. The secondary fluid serves as the working fluid in a heat engine. The author briefly examines the thermodynamic principles governing the operation of such engines, the major thermodynamic cycles used, and their application to nuclear power plants. (Auth.)

  1. Superfluid thermodynamic cycle refrigerator

    Science.gov (United States)

    Swift, Gregory W.; Kotsubo, Vincent Y.

    1992-01-01

    A cryogenic refrigerator cools a heat source by cyclically concentrating and diluting the amount of .sup.3 He in a single phase .sup.3 He-.sup.4 He solution. The .sup.3 He in superfluid .sup.4 He acts in a manner of an ideal gas in a vacuum. Thus, refrigeration is obtained using any conventional thermal cycle, but preferably a Stirling or Carnot cycle. A single phase solution of liquid .sup.3 He at an initial concentration in superfluid .sup.4 He is contained in a first variable volume connected to a second variable volume through a superleak device that enables free passage of .sup.4 He while restricting passage of .sup.3 He. The .sup.3 He is compressed (concentrated) and expanded (diluted) in a phased manner to carry out the selected thermal cycle to remove heat from the heat load for cooling below 1 K.

  2. Power by waste heat recovery from low temperature industrial flue gas by Organic Flash Cycle (OFC) and transcritical-CO_2 power cycle: A comparative study through combined thermodynamic and economic analysis

    International Nuclear Information System (INIS)

    Mondal, Subha; De, Sudipta

    2017-01-01

    Both Organic flash cycle and transcritical CO_2 power cycle (T-CO_2 power cycle) allow cooling of hot flue gas stream to an appreciably lower temperature due to the absence of pinch limitation. In the present study, a combined thermodynamic and economic comparison is conducted between a T-CO_2 power cycle and Organic flash cycles using R-245fa and R600 as the working fluids. It is observed that work output per kg of flue gas flow rate is slightly higher for the T-CO_2 power cycle if the flue gas is allowed to cool to the corresponding lowest possible temperature in the Heat Recovery Unit (HRU). It is also observed that with maximum possible cooling of flue gas, minimum bare module costs (BMCs) for each kW power output of OFCs are somewhat higher compared to that of T-CO_2 power cycle. Minimum BMCs for each kW output of OFCs can be reduced substantially by increasing terminal temperature difference at the low temperature end of the HRU. However, the increasing terminal temperature difference at the low temperature end of the HRU is having negligible effect on BMC ($/kW) of T-CO_2 power cycle. - Highlights: • Combined thermodynamic and economic analysis done for T-CO_2 power cycle and OFC. • With highest heat recovery, T-CO_2 cycle produces slightly higher work output/kg of flue gas. • With highest heat recovery, minimum bare module costs in $/kW is slightly higher for OFCs. • Work outputs/kg of flue gas of all cycles are almost equal for these minimum BMCs. • BMCs in $/kW for OFCs sharply decrease with larger flue gas exit temperature.

  3. Comparison of the leading candidate combinations of blanket materials, thermodynamic cycles, and tritium systems for full scale fusion power plants

    International Nuclear Information System (INIS)

    Fraas, A.P.

    1975-01-01

    The many possible combinations of blanket materials, tritium generation and recovery systems, and power conversion systems were surveyed and a comprehensive set of designs were generated by using a common set of ground rules that include all of the boundary conditions that could be envisioned for a full-scale commercial fusion power plant. Particular attention was given to the effects of blanket temperature on power plant cycle efficiency and economics, the interdependence of the thermodynamic cycle and the tritium recovery system, and to thermal and pressure stresses in the blanket structure. The results indicate that, of the wide variety of systems that have been considered, the most promising employs lithium recirculated in a closed loop within a niobium blanket structure and cooled with boiling potassium or cesium. This approach gives the simplest and lowest cost tritium recovery system, the lowest pressure and thermal stresses, the simplest structure with the lowest probability of a leak, the greatest resistance to damage from a plasma energy dump, and the lowest rate of plasma contamination by either outgassing or sputtering. The only other blanket materials combination that appears fairly likely to give a satisfactory tritium generation and recovery system is a lithium-beryllium fluoride-Incoloy blanket, and even this system involves major uncertainties in the effectiveness, size, and cost of the tritium recovery system. Further, the Li 2 BeF 4 blanket system has the disadvantage that the world reserves of beryllium are too limited to support a full-blown fusion reactor economy, its poor thermal conductivity leads to cooling difficulties and a requirement for a complex structure with intricate cooling passages, and this inherently leads to an expansive blanket with a relatively high probability of leaks. The other blanket materials combinations yield even less attractive systems

  4. Thermodynamic analysis of a low-temperature organic Rankine cycle power plant operating at off-design conditions

    International Nuclear Information System (INIS)

    He, Zhonglu; Zhang, Yufeng; Dong, Shengming; Ma, Hongting; Yu, Xiaohui; Zhang, Yan; Ma, Xuelian; Deng, Na; Sheng, Ying

    2017-01-01

    Highlights: • An ORC power plant driven by low grade heat source is set up. • Energy and exergy analysis at off-design conditions is conducted. • The twin screw expander performance is characterized. • An empirical model to predict the net power output and thermal efficiency. - Abstract: This paper deals with an experimental study on a 50-kW Organic Rankine cycle (ORC) power generation plant driven by low-grade heat source. Hot water boiler and solar-thermal system were used as the low-grade heat source providing hot water at temperature ranging from 65 to 95 °C. A twin screw compressor has been modified as the expansion machine in the ORC module and its expansion efficiency under variable operating conditions was tested in the experiments. This work was purposed to assess the ORC system and get the performance map at off-design operating conditions in a typical year from the view of the first and the second law of thermodynamics. The maximum electricity production and thermal efficiency were 46.5 kW and 6.52% respectively at the optimal operating condition. The highest exergetic efficiency reached 36.3% and the exergy analysis showed that evaporation pressure and condensation pressure were the key parameters to influence the exergy flow and exergetic efficiency. Furthermore, by fitting the actual plant data obtained in different months, an empirical model has been developed to predict the net power output and thermal efficiency with acceptable accuracy. Lastly, as an illustration, the empirical model is used to analyze the performance of the solar-driven ORC system.

  5. ORCENT-2, Full Load Steam Turbine Cycle Thermodynamics for LWR Power Plant

    International Nuclear Information System (INIS)

    Fuller, L.C.

    1979-01-01

    1 - Description of problem or function: ORCENT-2 performs heat and mass balance calculations at valves-wide-open design conditions, maximum guaranteed rating conditions, and an approximation of part-load conditions for steam turbine cycles supplied with throttle steam, characteristic of contemporary light-water reactors. The program handles both condensing and back-pressure turbine exhaust arrangements. Turbine performance calculations are based on the General Electric Company method for 1800-rpm large steam turbine- generators operating with light-water-cooled nuclear reactors. Output includes all information normally shown on a turbine-cycle heat balance diagram. 2 - Method of solution: The turbine performance calculations follow the procedures outlined in General Electric report GET-6020. ORCENT-2 utilizes the 1967 American Society of Mechanical Engineers (ASME) formulations and procedures for calculating the properties of steam, adapted for ORNL use by D.W. Altom. 3 - Restrictions on the complexity of the problem: Maxima of: 12 feed-water heaters, 5 moisture removal stages in the low-pressure turbine section. ORCENT-2 is limited to 1800-rpm tandem-compound turbine-generators with single- or double-flow high pressure sections and one, two, or three double-flow low-pressure turbine sections. Steam supply for LWR cycles should be between 900 and 1100 psia and slightly wet to 100 degrees F of initial superheat. Generator rating should be greater than 100 MVA

  6. Detonation Jet Engine. Part 1--Thermodynamic Cycle

    Science.gov (United States)

    Bulat, Pavel V.; Volkov, Konstantin N.

    2016-01-01

    We present the most relevant works on jet engine design that utilize thermodynamic cycle of detonative combustion. The efficiency advantages of thermodynamic detonative combustion cycle over Humphrey combustion cycle at constant volume and Brayton combustion cycle at constant pressure were demonstrated. An ideal Ficket-Jacobs detonation cycle, and…

  7. Thermodynamic performance analysis of a combined power cycle using low grade heat source and LNG cold energy

    International Nuclear Information System (INIS)

    Kim, Kyoung Hoon; Kim, Kyung Chun

    2014-01-01

    Thermodynamic analysis of a combined cycle using a low grade heat source and LNG cold energy was carried out. The combined cycle consisted of an ammonia–water Rankine cycle with and without regeneration and a LNG Rankine cycle. A parametric study was conducted to examine the effects of the key parameters, such as ammonia mass fraction, turbine inlet pressure, condensation temperature. The effects of the ammonia mass fraction on the temperature distributions of the hot and cold streams in heat exchangers were also investigated. The characteristic diagram of the exergy efficiency and heat transfer capability was proposed to consider the system performance and expenditure of the heat exchangers simultaneously. The simulation showed that the system performance is influenced significantly by the parameters with the ammonia mass fraction having largest effect. The net work output of the ammonia–water cycle may have a peak value or increase monotonically with increasing ammonia mass fraction, which depends on turbine inlet pressure or condensation temperature. The exergy efficiency may decrease or increase or have a peak value with turbine inlet pressure depending on the ammonia mass fraction. - Highlights: • Thermodynamic analysis was performed for a combined cycle utilizing LNG cold energy. • Ammonia–water Rankine cycle and LNG Rankine cycle was combined. • A parametric study was conducted to examine the effects of the key parameters. • Characteristics of the exergy efficiency and heat transfer capability were proposed. • The system performance was influenced significantly by the ammonia mass fraction

  8. Integrated working fluid-thermodynamic cycle design of organic Rankine cycle power systems for waste heat recovery

    DEFF Research Database (Denmark)

    Cignitti, Stefano; Andreasen, Jesper Graa; Haglind, Fredrik

    2017-01-01

    recovery. Inthis paper, an organic Rankine cycle process and its pure working fluid are designed simultaneously forwaste heat recovery of the exhaust gas from a marine diesel engine. This approach can overcome designissues caused by the high sensitivity between the fluid and cycle design variables......Today, some established working fluids are being phased out due to new international regulations on theuse of environmentally harmful substances. With an ever-increasing cost to resources, industry wants toconverge on improved sustainability through resource recovery, and in particular waste heat...

  9. Thermodynamic optimization of power plants

    NARCIS (Netherlands)

    Haseli, Y.

    2011-01-01

    Thermodynamic Optimization of Power Plants aims to establish and illustrate comparative multi-criteria optimization of various models and configurations of power plants. It intends to show what optimization objectives one may define on the basis of the thermodynamic laws, and how they can be applied

  10. Thermodynamic power stations at low temperatures

    Science.gov (United States)

    Malherbe, J.; Ployart, R.; Alleau, T.; Bandelier, P.; Lauro, F.

    The development of low-temperature thermodynamic power stations using solar energy is considered, with special attention given to the choice of the thermodynamic cycle (Rankine), working fluids (frigorific halogen compounds), and heat exchangers. Thermomechanical conversion machines, such as ac motors and rotating volumetric motors are discussed. A system is recommended for the use of solar energy for irrigation and pumping in remote areas. Other applications include the production of cold of fresh water from brackish waters, and energy recovery from hot springs.

  11. Thermodynamic and economic studies of two new high efficient power-cooling cogeneration systems based on Kalina and absorption refrigeration cycles

    International Nuclear Information System (INIS)

    Rashidi, Jouan; Ifaei, Pouya; Esfahani, Iman Janghorban; Ataei, Abtin; Yoo, Chang Kyoo

    2016-01-01

    Highlights: • Proposing two new power and cooling cogeneration systems based on absorption chillers and Kalina cycles. • Model-based comparison through thermodynamic and economic standpoints. • Investigating sensitivity of system performance and costs to the key parameters. • Reducing total annual costs of the base system up to 8% by cogeneration. • Increasing thermal efficiency up to 4.9% despite of cooling generation. - Abstract: Two new power and cooling cogeneration systems based on Kalina cycle (KC) and absorption refrigeration cycle (AC) are proposed and studied from thermodynamic and economic viewpoints. The first proposed system, Kalina power-cooling cycle (KPCC), combines the refrigerant loop of the water-ammonia absorption chiller, consisting of an evaporator and two throttling valves with the KC. A portion of the KC mass flow enters the evaporator to generate cooling after being condensed in the KPCC system. KPCC is a flexible system adapting power and cooling cogeneration to the demand. The second proposed system, Kalina lithium bromide absorption chiller cycle (KLACC), consists of the KC and a single effect lithium bromide-water absorption chiller (AC_L_i_B_r_-_w_a_t_e_r). The KC subsystem discharges heat to the AC_L_i_B_r_-_w_a_t_e_r desorber before condensing in the condenser. The performance and economic aspects of both proposed systems are analyzed and compared with the stand alone KC. A parametric analysis is conducted to evaluate the sensitivity of efficiencies and the generated power and cooling quantities to the key operating variables. The results showed that, thermal efficiency and total annual costs decreased by 5.6% and 8% for KPCC system but increased 4.9% and 58% for KLACC system, respectively. Since the power-cooling efficiency of KLACC is 42% higher than KPCC it can be applied where the aim is cooling generation without considering economic aspects.

  12. Thermodynamic analysis of a nuclear-hydrogen power system using H2/O2 direct combustion product as a working substance in the bottom cycle

    International Nuclear Information System (INIS)

    Chen, D.Z.; Yu, C.P.

    1990-01-01

    A combined thermodynamic cycle using nuclear and hydrogen energy as heat sources was investigated in this paper. The cycle is composed of top cycle using HTGR as energy source and helium as working medium and a bottom cycle with H 2 /O 2 direct combustion product as working substance. hydrogen and oxygen are thermochemically by splitting of water produced through a part of nuclear heat recovered from the top cycle. They may be delivered to the O 2 /H 2 users or used as fuels for the high temperature bottom Rankine steam cycle. The combined cycle not only uses the new energy sources instead of conventional fossil fuels but it possess the advantages of both helium and steam cycle. It has a high thermal efficiency, large unit capacity, many-sided usage and less pollution. It may represent a new type of combined cycles for future energy conversion and power generation. Using computer diagram, a variety of schemes were calculated and analyzed. The influence of some main parameters upon the cycle performance were also studied

  13. Thermodynamic simulation of CO{sub 2} capture for an IGCC power plant using the calcium looping cycle

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y. [National Engineering Laboratory for Coal-Burning Pollutant Emission Reduction, Shandong University, Jinan (China); Zhao, C.; Ren, Q. [School of Energy and Environment, Southeast University, Nanjing (China)

    2011-06-15

    A CO{sub 2} capture process for an integrated gasification combined cycle (IGCC) power plant using the calcium looping cycle was proposed. The CO{sub 2} capture process using natural and modified limestone was simulated and investigated with the software package Aspen Plus. It incorporated a fresh feed of sorbent to compensate for the decay in CO{sub 2} capture activity during long-term cycles. The sorbent flow ratios have significant effect on the CO{sub 2} capture efficiency and net efficiency of the CO{sub 2} capture system. The IGCC power plant, using the modified limestone, exhibits higher CO{sub 2} capture efficiency than that using the natural limestone at the same sorbent flow ratios. The system net efficiency using the natural and modified limestones achieves 41.7% and 43.1%, respectively, at the CO{sub 2} capture efficiency of 90% without the effect of sulfation. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Thermodynamic cycles of adsorption desalination system

    International Nuclear Information System (INIS)

    Wu, Jun W.; Hu, Eric J.; Biggs, Mark J.

    2012-01-01

    Highlights: ► Thermodynamic cycles of adsorption desalination (AD) system have been identified all possible evaporator temperature scenarios. ► Temperature of evaporator determines the cycle. ► Higher evaporator temperature leads to higher water production if no cooling is required. -- Abstract: The potential to use waste heat to co-generate cooling and fresh water from saline water using adsorption on silica is attracting increasing attention. A variety of different thermodynamic cycles of such an adsorption desalination (AD) system arise as the temperature of the saline water evaporator is varied relative to temperature of the water used to cool the adsorbent as it adsorbs the evaporated water. In this paper, all these possible thermodynamic cycles are enumerated and analysed to determine their relative performances in terms of specific energy consumption and fresh water productivity.

  15. Thermodynamic studies of a HAT cycle and its components

    International Nuclear Information System (INIS)

    Nyberg, Bjoern; Thern, Marcus

    2012-01-01

    Highlights: → Performance maps for HAT cycles with different complexity are shown. → A suggestion, where to extract cooling air for the turbine is presented. → The influence of the makeup water on total efficiency is shown. → The optimal pressure level for intercooling is described. -- Abstract: The electric power grid contains more and more renewable power production such as wind and solar power. The use of renewable power sources increases the fluctuations in the power grid which increase the demand for highly efficient, fast-starting power-producing units that can cope with sudden production losses. One of the more innovative power plant cycles, that have the potential of competing with conventional combined power plants in efficiency but has a higher availability and faster start up time, is the Evaporative Gas Turbine (EvGT) or Humid Air Turbine (HAT). A thermodynamic evaluation of different HAT cycle layouts has been done in this paper. Each layout is evaluated separately which makes it possible to study different components individual contribution to the efficiency and specific power. The thermodynamic evaluation also shows that it is important to look at different cool-flow extracting positions. The effect of water temperature entering the cycle, called make-up water, and where it is introduced into the cycle has been evaluated. The make-up water temperature also affects the optimal pressure level for intercooling and it is shown that an optimal position can be decided considering design parameters of the compressor and the water circuit.

  16. Heat pipe thermodynamic cycle and its applications

    International Nuclear Information System (INIS)

    Kobayashi, Y.

    1985-01-01

    A new type of thermodynamic cycle originating from extended application of the heat pipe principle is proposed and its thermal cycle is discussed from the viewpoint of theoretical thermal efficiency and Coefficient of Performance. An idealized structure that will meet the basic function for thermal systems is also suggested. A significant advantage of these systems is their use with lowtemperature energy sources found in nature or heat rejected from industrial sites

  17. Efficiency of an air-cooled thermodynamic cycle

    International Nuclear Information System (INIS)

    Bezborodov, Yu.A.; Bubnov, V.P.; Nesterenko, V.B.

    1979-01-01

    The application of air, nitrogen, helium and the chemically reacting N 2 O 4 reversible 2NO 2 reversible 2NO + O 2 system as working agents and coolants for a low capacity nuclear power plant is investigated. The above system due to its physico-chemical and thermo-physical properties allows both a gaseous cycle and a cycle with condensation. The analysis has shown that a thermodynamic air-cooled cycle with the dissociating nitrogen tetroxide in the temperature range from 500 to 600 deg C has an advantage over cycles with air and nitrogen. To identify the chemical reaction kinetics in the thermodynamic processes, thermodynamic calculations of the gas-liquid cycle with N 2 O 4 both with simple and intermediate heat regeneration at different pressures over hot side were performed. At gas pressures lower than 12 - 15 atm, the cycle with a simple regeneration is more effective, and at pressure increase, the cycle with an intermediate regeneration is preferable

  18. Alternative thermodynamic cycle for the Stirling machine

    Science.gov (United States)

    Romanelli, Alejandro

    2017-12-01

    We develop an alternative thermodynamic cycle for the Stirling machine, where the polytropic process plays a central role. Analytical expressions for pressure and temperatures of the working gas are obtained as a function of the volume and the parameter that characterizes the polytropic process. This approach achieves closer agreement with the experimental pressure-volume diagram and can be adapted to any type of Stirling engine.

  19. Quantitative indexes of gas-steam thermo electrical power plants thermodynamical cycles; Indices quantitativos de ciclos termodinamicos de centrais termoeletricas de gas-vapor

    Energy Technology Data Exchange (ETDEWEB)

    Vlassov, D.; Vargas, J.V.C. [Parana Univ., Curitiba, PR (Brazil). Dept. de Engenharia Mecanica]. E-mails: vlassov@demec.ufpr.br; jvargas@demec.ufpr.br

    2002-07-01

    This paper analyses various thermal schemes of the world wide most used cycles in gas-steam thermoelectric power plants. The combination of gas turbine cycle with the steam-gas cycle in thermoelectric power plants is performed in several ways, resulting in different thermal schemes, used equipment and operation plant basic characteristics. The thermal scheme of a gas-steam power plant is a determinant factor for the definition of energetic, economic and ecological characteristics. For the comparative analysis various quantitative indexes are presented, as for example: the heat fraction supplied to the gas turbine cycle and the cycle binary rate.

  20. Thermodynamic Analysis of an Irreversible Maisotsenko Reciprocating Brayton Cycle

    Directory of Open Access Journals (Sweden)

    Fuli Zhu

    2018-03-01

    Full Text Available An irreversible Maisotsenko reciprocating Brayton cycle (MRBC model is established using the finite time thermodynamic (FTT theory and taking the heat transfer loss (HTL, piston friction loss (PFL, and internal irreversible losses (IILs into consideration in this paper. A calculation flowchart of the power output (P and efficiency (η of the cycle is provided, and the effects of the mass flow rate (MFR of the injection of water to the cycle and some other design parameters on the performance of cycle are analyzed by detailed numerical examples. Furthermore, the superiority of irreversible MRBC is verified as the cycle and is compared with the traditional irreversible reciprocating Brayton cycle (RBC. The results can provide certain theoretical guiding significance for the optimal design of practical Maisotsenko reciprocating gas turbine plants.

  1. Pyroelectric Energy Harvesting: With Thermodynamic-Based Cycles

    OpenAIRE

    Saber Mohammadi; Akram Khodayari

    2012-01-01

    This work deals with energy harvesting from temperature variations using ferroelectric materials as a microgenerator. The previous researches show that direct pyroelectric energy harvesting is not effective, whereas thermodynamic-based cycles give higher energy. Also, at different temperatures some thermodynamic cycles exhibit different behaviours. In this paper pyroelectric energy harvesting using Lenoir and Ericsson thermodynamic cycles has been studied numerically and the two cycles were c...

  2. Advanced adsorption cooling cum desalination cycle: A thermodynamic framework

    KAUST Repository

    Chakraborty, Anutosh; Thu, Kyaw; Ng, K. C.

    2011-01-01

    We have developed a thermodynamic framework to calculate adsorption cooling cum desalination cycle performances as a function of pore widths and pore volumes of highly porous adsorbents, which are formulated from the rigor of thermodynamic property

  3. Thermodynamic Optimization of Supercritical CO{sub 2} Brayton Cycles

    Energy Technology Data Exchange (ETDEWEB)

    Rhim, Dong-Ryul; Park, Sung-Ho; Kim, Su-Hyun; Yeom, Choong-Sub [Institute for Advanced Engineering, Yongin (Korea, Republic of)

    2015-05-15

    The supercritical CO{sub 2} Brayton cycle has been studied for nuclear applications, mainly for one of the alternative power conversion systems of the sodium cooled fast reactor, since 1960's. Although the supercritical CO{sub 2} Brayton cycle has not been expected to show higher efficiency at lower turbine inlet temperature over the conventional steam Rankine cycle, the higher density of supercritical CO{sub 2} like a liquid in the supercritical region could reduce turbo-machinery sizes, and the potential problem of sodium-water reaction with the sodium cooled fast reactor might be solved with the use of CO{sub 2} instead of water. The supercritical CO{sub 2} recompression Brayton cycle was proposed for the better thermodynamic efficiency than for the simple supercritical CO{sub 2} Brayton cycle. Thus this paper presents the efficiencies of the supercritical CO{sub 2} recompression Brayton cycle along with several decision variables for the thermodynamic optimization of the supercritical CO{sub 2} recompression Brayton cycle. The analytic results in this study show that the system efficiency reaches its maximum value at a compressor outlet pressure of 200 bars and a recycle fraction of 30 %, and the lower minimum temperature approach at the two heat exchangers shows higher system efficiency as expected.

  4. Thermodynamic analysis of a simple Organic Rankine Cycle

    International Nuclear Information System (INIS)

    Javanshir, Alireza; Sarunac, Nenad

    2017-01-01

    Thermodynamic performance (thermal efficiency and net power output) of a simple subcritical and supercritical Organic Rankine Cycle (ORC) was analyzed over a range of operating conditions for a number of working fluids to determine the effect of operating parameters on cycle performance and select the best working fluid. The results show that for an ORC operating with a dry working fluid, thermal efficiency decreases with an increase in the turbine inlet temperature (TIT) due to the convergence of the isobaric lines with temperature. The results also show that efficiency of an ORC operating with isentropic working fluids is higher compared to the dry and wet fluids, and working fluids with higher specific heat capacity provide higher cycle net power output. New expressions for thermal efficiency of a subcritical and supercritical simple ORC are proposed. For a subcritical ORC without the superheat, thermal efficiency is expressed as a function of the Figure of Merit (FOM), while for the superheated subcritical ORC thermal efficiency is given in terms of the modified Jacob number. For the supercritical ORC, thermal efficiency is expressed as a function of dimensionless temperature. - Highlights: • Analyzing thermodynamic performance of ORC over a range of operating conditions. • Selecting the best working fluid suitable for a simple ORC. • Proposing new expressions for thermal efficiency of a simple ORC.

  5. Thermodynamic analysis of steam-injected advanced gas turbine cycles

    Science.gov (United States)

    Pandey, Devendra; Bade, Mukund H.

    2017-12-01

    This paper deals with thermodynamic analysis of steam-injected gas turbine (STIGT) cycle. To analyse the thermodynamic performance of steam-injected gas turbine (STIGT) cycles, a methodology based on pinch analysis is proposed. This graphical methodology is a systematic approach proposed for a selection of gas turbine with steam injection. The developed graphs are useful for selection of steam-injected gas turbine (STIGT) for optimal operation of it and helps designer to take appropriate decision. The selection of steam-injected gas turbine (STIGT) cycle can be done either at minimum steam ratio (ratio of mass flow rate of steam to air) with maximum efficiency or at maximum steam ratio with maximum net work conditions based on the objective of plants designer. Operating the steam injection based advanced gas turbine plant at minimum steam ratio improves efficiency, resulting in reduction of pollution caused by the emission of flue gases. On the other hand, operating plant at maximum steam ratio can result in maximum work output and hence higher available power.

  6. 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

  7. Quantum thermodynamic cycles and quantum heat engines. II.

    Science.gov (United States)

    Quan, H T

    2009-04-01

    We study the quantum-mechanical generalization of force or pressure, and then we extend the classical thermodynamic isobaric process to quantum-mechanical systems. Based on these efforts, we are able to study the quantum version of thermodynamic cycles that consist of quantum isobaric processes, such as the quantum Brayton cycle and quantum Diesel cycle. We also consider the implementation of the quantum Brayton cycle and quantum Diesel cycle with some model systems, such as single particle in a one-dimensional box and single-mode radiation field in a cavity. These studies lay the microscopic (quantum-mechanical) foundation for Szilard-Zurek single-molecule engine.

  8. Thermodynamic cycle calculations for a pumped gaseous core fission reactor

    International Nuclear Information System (INIS)

    Kuijper, J.C.; Van Dam, H.

    1991-01-01

    Finite and 'infinitesimal' thermodynamic cycle calculations have been performed for a 'solid piston' model of a pumped Gaseous Core Fission Reactor with dissociating reactor gas, consisting of Uranium, Carbon and Fluorine ('UCF'). In the finite cycle calculations the influence has been investigated of several parameters on the thermodynamics of the system, especially on the attainable direct (nuclear to electrical) energy conversion efficiency. In order to facilitate the investigation of the influence of dissociation, a model gas, 'Modelium', was developed, which approximates, in a simplified, analytical way, the dissociation behaviour of the 'real' reactor gas. Comparison of the finite cycle calculation results with those of a so-called infinitesimal Otto cycle calculation leads to the conclusion that the conversion efficiency of a finite cycle can be predicted, without actually performing the finite cycle calculation, with reasonable accuracy, from the so-called 'infinitesimal efficiency factor', which is determined only by the thermodynamic properties of the reactor gas used. (author)

  9. Heat recovery from Diesel engines: A thermodynamic comparison between Kalina and ORC cycles

    International Nuclear Information System (INIS)

    Bombarda, Paola; Invernizzi, Costante M.; Pietra, Claudio

    2010-01-01

    In the context of heat recovery for electric power generation, Kalina cycle (a thermodynamic cycle using as working fluid a mixture of water and ammonia) and Organic Rankine Cycle (ORC) represent two different eligible technologies. In this work a comparison between the thermodynamic performances of Kalina cycle and an ORC cycle, using hexamethyldisiloxane as working fluid, was conducted for the case of heat recovery from two Diesel engines, each one with an electrical power of 8900 kWe. The maximum net electric power that can be produced exploiting the heat source constituted by the exhaust gases mass flow (35 kg/s for both engines, at 346 deg. C) was calculated for the two thermodynamic cycles. Owing to the relatively low useful power, for the Kalina cycle a relatively simple plant layout was assumed. Supposing reasonable design parameters and a logarithmic mean temperature difference in the heat recovery exchanger of 50 deg. C, a net electric power of 1615 kW and of 1603 kW respectively for the Kalina and for the ORC cycle was calculated. Although the obtained useful powers are actually equal in value, the Kalina cycle requires a very high maximum pressure in order to obtain high thermodynamic performances (in our case, 100 bar against about 10 bar for the ORC cycle). So, the adoption of Kalina cycle, at least for low power level and medium-high temperature thermal sources, seems not to be justified because the gain in performance with respect to a properly optimized ORC is very small and must be obtained with a complicated plant scheme, large surface heat exchangers and particular high pressure resistant and no-corrosion materials.

  10. Numerical Analysis of Integral Characteristics for the Condenser Setups of Independent Power-Supply Sources with the Closed-Looped Thermodynamic Cycle

    Directory of Open Access Journals (Sweden)

    Vysokomorny Vladimir S.

    2016-01-01

    Full Text Available The mathematical model of heat and mass transfer processes with phase transition is developed. It allows analyzing of integral characteristics for the condenser setup of independent power-supply plant with the organic Rankine cycle. Different kinds of organic liquids can be used as a coolant and working substance. The temperatures of the working liquid at the condenser outlet under different values of outside air temperature are determined. The comparative analysis of the utilization efficiency of different cooling systems and organic coolants is carried out.

  11. Numerical Analysis of Integral Characteristics for the Condenser Setups of Independent Power-Supply Sources with the Closed-Looped Thermodynamic Cycle

    Directory of Open Access Journals (Sweden)

    Olga V. Vysokomornaya

    2015-01-01

    Full Text Available The mathematical model of heat and mass transfer processes with phase transition is developed. It allows analysis of integral characteristics for the condenser setup of independent power-supply plant with the organic Rankine cycle. Different kinds of organic liquids can be used as a coolant and working substance. The temperatures of the working liquid at the condenser outlet under different values of outside air temperature are determined. The comparative analysis of the utilization efficiency of different cooling systems and organic coolants is carried out.

  12. Thermodynamic design of natural gas liquefaction cycles for offshore application

    Science.gov (United States)

    Chang, Ho-Myung; Lim, Hye Su; Choe, Kun Hyung

    2014-09-01

    A thermodynamic study is carried out for natural gas liquefaction cycles applicable to offshore floating plants, as partial efforts of an ongoing governmental project in Korea. For offshore liquefaction, the most suitable cycle may be different from the on-land LNG processes under operation, because compactness and simple operation are important as well as thermodynamic efficiency. As a turbine-based cycle, closed Claude cycle is proposed to use NG (natural gas) itself as refrigerant. The optimal condition for NG Claude cycle is determined with a process simulator (Aspen HYSYS), and the results are compared with fully-developed C3-MR (propane pre-cooled mixed refrigerant) JT cycles and various N2 (nitrogen) Brayton cycles in terms of efficiency and compactness. The newly proposed NG Claude cycle could be a good candidate for offshore LNG processes.

  13. Thermodynamic Modeling for Open Combined Regenerative Brayton and Inverse Brayton Cycles with Regeneration before the Inverse Cycle

    Directory of Open Access Journals (Sweden)

    Lingen Chen

    2012-01-01

    Full Text Available A thermodynamic model of an open combined regenerative Brayton and inverse Brayton cycles with regeneration before the inverse cycle is established in this paper by using thermodynamic optimization theory. The flow processes of the working fluid with the pressure drops and the size constraint of the real power plant are modeled. There are 13 flow resistances encountered by the working fluid stream for the cycle model. Four of these, the friction through the blades and vanes of the compressors and the turbines, are related to the isentropic efficiencies. The remaining nine flow resistances are always present because of the changes in flow cross-section at the compressor inlet of the top cycle, regenerator inlet and outlet, combustion chamber inlet and outlet, turbine outlet of the top cycle, turbine outlet of the bottom cycle, heat exchanger inlet, and compressor inlet of the bottom cycle. These resistances associated with the flow through various cross-sectional areas are derived as functions of the compressor inlet relative pressure drop of the top cycle, and control the air flow rate, the net power output and the thermal efficiency. The analytical formulae about the power output, efficiency and other coefficients are derived with 13 pressure drop losses. It is found that the combined cycle with regenerator can reach higher thermal efficiency but smaller power output than those of the base combined cycle at small compressor inlet relative pressure drop of the top cycle.

  14. Thermodynamic cycle analysis for capacitive deionization

    NARCIS (Netherlands)

    Biesheuvel, P.M.

    2009-01-01

    Capacitive deionization (CDI) is an ion removal technology based on temporarily storing ions in the polarization layers of two oppositely positioned electrodes. Here we present a thermodynamic model for the minimum work required for ion separation in the fully reversible case by describing the ionic

  15. Alternative ORC bottoming cycles FOR combined cycle power plants

    International Nuclear Information System (INIS)

    Chacartegui, R.; Sanchez, D.; Munoz, J.M.; Sanchez, T.

    2009-01-01

    In this work, low temperature Organic Rankine Cycles are studied as bottoming cycle in medium and large scale combined cycle power plants. The analysis aims to show the interest of using these alternative cycles with high efficiency heavy duty gas turbines, for example recuperative gas turbines with lower gas turbine exhaust temperatures than in conventional combined cycle gas turbines. The following organic fluids have been considered: R113, R245, isobutene, toluene, cyclohexane and isopentane. Competitive results have been obtained for toluene and cyclohexane ORC combined cycles, with reasonably high global efficiencies. The paper is structured in four main parts. A review of combined cycle and ORC cycle technologies is presented, followed by a thermodynamic analysis of combined cycles with commercial gas turbines and ORC low temperature bottoming cycles. Then, a parametric optimization of an ORC combined cycle plant is performed in order to achieve a better integration between these two technologies. Finally, some economic considerations related to the use of ORC in combined cycles are discussed.

  16. Not all counterclockwise thermodynamic cycles are refrigerators

    Science.gov (United States)

    Dickerson, R. H.; Mottmann, J.

    2016-06-01

    Clockwise cycles on PV diagrams always represent heat engines. It is therefore tempting to assume that counterclockwise cycles always represent refrigerators. This common assumption is incorrect: most counterclockwise cycles cannot be refrigerators. This surprising result is explored here for quasi-static ideal gas cycles, and the necessary conditions for refrigeration cycles are clarified. Three logically self-consistent criteria can be used to determine if a counterclockwise cycle is a refrigerator. The most fundamental test compares the counterclockwise cycle with a correctly determined corresponding Carnot cycle. Other criteria we employ include a widely accepted description of the functional behavior of refrigerators, and a corollary to the second law that limits a refrigerator's coefficient of performance.

  17. The nuclear power cycle

    International Nuclear Information System (INIS)

    2004-01-01

    Fifty years after the first nuclear reactor come on-line, nuclear power is fourth among the world's primary energy sources, after oil, coal and gas. In 2002, there were 441 reactors in operation worldwide. The United States led the world with 104 reactors and an installed capacity of 100,000 MWe, or more than one fourth of global capacity. Electricity from nuclear energy represents 78% of the production in France, 57% in Belgium, 46% in Sweden, 40% in Switzerland, 39% in South Korea, 34% in Japan, 30% in Germany, 30% in Finland, 26% in Spain, 22% in Great Britain, 20% in the United States and 16% in Russia. Worldwide, 32 reactors are under construction, including 21 in Asia. This information document presents the Areva activities in the nuclear power cycle: the nuclear fuel, the nuclear reactors, the spent fuel reprocessing and recycling and nuclear cleanup and dismantling. (A.L.B.)

  18. Thermodynamic calculation of a district energy cycle

    International Nuclear Information System (INIS)

    Hoehlein, B.; Bauer, A.; Kraut, G.; Scherberich, F.D.

    1975-08-01

    This paper presents a calculation model for a nuclear district energy circuit. Such a circuit means the combination of a steam reforming plant with heat supply from a high-temperature nuclear reactor and a methanation plant with heat production for district heating or electricity production. The model comprises thermodynamic calculations for the endothermic methane reforming reaction as well as the exothermic CO-hydrogenation in adiabatic reactors and allows the optimization of the district energy circuit under consideration. (orig.) [de

  19. A thermodynamic study of waste heat recovery from GT-MHR using organic Rankine cycles

    International Nuclear Information System (INIS)

    Yari, Mortaza; Mahmoudi, S.M.S.

    2011-01-01

    This paper presents an investigation on the utilization of waste heat from a gas turbine-modular helium reactor (GT-MHR) using different arrangements of organic Rankine cycles (ORCs) for power production. The considered organic Rankine cycles were: simple organic Rankine cycle (SORC), ORC with internal heat exchanger (HORC) and regenerative organic Rankine cycle (RORC). The performances of the combined cycles were studied from the point of view of first and second-laws of thermodynamics. Individual models were developed for each component and the effects of some important parameters such as compressor pressure ratio, turbine inlet temperature, and evaporator and environment temperatures on the efficiencies and on the exergy destruction rate were studied. Finally the combined cycles were optimized thermodynamically using the EES (Engineering Equation Solver) software. Based on the identical operating conditions for the GT-MHR cycle, a comparison between the three combined cycles and a simple GT-MHR cycle is also were made. This comparison was also carried out from the point of view of economics. The GT-MHR/SORC combined cycle proved to be the best among all the cycles from the point of view of both thermodynamics and economics. The efficiency of this cycle was about 10% higher than that of GT-MHR alone. (orig.)

  20. Advanced adsorption cooling cum desalination cycle: A thermodynamic framework

    KAUST Repository

    Chakraborty, Anutosh

    2011-01-01

    We have developed a thermodynamic framework to calculate adsorption cooling cum desalination cycle performances as a function of pore widths and pore volumes of highly porous adsorbents, which are formulated from the rigor of thermodynamic property surfaces of adsorbent-adsorbate system and the adsorption interaction potential between them. Employing the proposed formulations, the coefficient of performance (COP) and overall performance ratio (OPR) of adsorption cycle are computed for various pore widths of solid adsorbents. These results are compared with experimental data for verifying the proposed thermodynamic formulations. It is found from the present analysis that the COP and OPR of adsorption cooling cum desalination cycle is influenced by (i) the physical characteristics of adsorbents, (ii) characteristics energy and (iii) the surface-structural heterogeneity factor of adsorbent-water system. The present study confirms that there exists a special type of adsorbents having optimal physical characteristics that allows us to obtain the best performance.

  1. Exergetical analysis of combustion, heat transfers, thermodynamical cycles and their applications

    International Nuclear Information System (INIS)

    Buchet, E.

    1983-11-01

    Exergetic analysis allowed to show up and evaluate irreversibilities in combustion, vapor exchanges and thermodynamic cycles, and also to justify processes often used to improve yields of thermal and energetic plants, and among them some more and more complex in cogeneration plants. This analysic method has been applied to thermal or nuclear steam power plant, to gas turbines and to cogeneration [fr

  2. Nuclear power fuel cycle

    International Nuclear Information System (INIS)

    Havelka, S.; Jakesova, L.

    1982-01-01

    Economic problems are discussed of the fuel cycle (cost of the individual parts of the fuel cycle and the share of the fuel cycle in the price of 1 kWh), the technological problems of the fuel cycle (uranium ore mining and processing, uranium isotope enrichment, the manufacture of fuel elements, the building of long-term storage sites for spent fuel, spent fuel reprocessing, liquid and gaseous waste processing), and the ecologic aspects of the fuel cycle. (H.S.)

  3. Thermodynamic evaluation of the Kalina split-cycle concepts for waste heat recovery applications

    International Nuclear Information System (INIS)

    Nguyen, Tuong-Van; Knudsen, Thomas; Larsen, Ulrik; Haglind, Fredrik

    2014-01-01

    The Kalina split-cycle is a thermodynamic process for converting thermal energy into electrical power. It uses an ammonia–water mixture as a working fluid (like a conventional Kalina cycle) and has a varying ammonia concentration during the pre-heating and evaporation steps. This second feature results in an improved match between the heat source and working fluid temperature profiles, decreasing the entropy generation in the heat recovery system. The present work compares the thermodynamic performance of this power cycle with the conventional Kalina process, and investigates the impact of varying boundary conditions by conducting an exergy analysis. The design parameters of each configuration were determined by performing a multi-variable optimisation. The results indicate that the Kalina split-cycle with reheat presents an exergetic efficiency by 2.8% points higher than a reference Kalina cycle with reheat, and by 4.3% points without reheat. The cycle efficiency varies by 14% points for a variation of the exhaust gas temperature of 100 °C, and by 1% point for a cold water temperature variation of 30 °C. This analysis also pinpoints the large irreversibilities in the low-pressure turbine and condenser, and indicates a reduction of the exergy destruction by about 23% in the heat recovery system compared to the baseline cycle. - Highlights: • The thermodynamic performance of the Kalina split-cycle is assessed. • The Kalina split-cycle is compared to the Kalina cycle, with and without reheat. • An exergy analysis is performed to evaluate its thermodynamic performance. • The impact of varying boundary conditions is investigated. • The Kalina split-cycle displays high exergetic efficiency for low- and medium-temperature applications

  4. Optimum heat power cycles for specified boundary conditions

    International Nuclear Information System (INIS)

    Ibrahim, O.M.; Klein, S.A.; Mitchell, J.W.

    1991-01-01

    In this paper optimization of the power output of Carnot and closed Brayton cycles is considered for both finite and infinite thermal capacitance rates of the external fluid streams. The method of Lagrange multipliers is used to solve for working fluid temperatures that yield maximum power. Analytical expressions for the maximum power and the cycle efficiency at maximum power are obtained. A comparison of the maximum power from the two cycles for the same boundary conditions, i.e., the same heat source/sink inlet temperatures, thermal capacitance rates, and heat exchanger conductances, shows that the Brayton cycle can produce more power than the Carnot cycle. This comparison illustrates that cycles exist that can produce more power than the Carnot cycle. The optimum heat power cycle, which will provide the upper limit of power obtained from any thermodynamic cycle for specified boundary conditions and heat exchanger conductances is considered. The optimum heat power cycle is identified by optimizing the sum of the power output from a sequence of Carnot cycles. The shape of the optimum heat power cycle, the power output, and corresponding efficiency are presented. The efficiency at maximum power of all cycles investigated in this study is found to be equal to (or well approximated by) η = 1 - sq. root T L.in /φT H.in where φ is a factor relating the entropy changes during heat rejection and heat addition

  5. Numerical and experimental analyses of different magnetic thermodynamic cycles with an active magnetic regenerator

    International Nuclear Information System (INIS)

    Plaznik, Uroš; Tušek, Jaka; Kitanovski, Andrej; Poredoš, Alojz

    2013-01-01

    We have analyzed the influence of different magnetic thermodynamic cycles on the performance of a magnetic cooling device with an active magnetic regenerator (AMR) based on the Brayton, Ericsson and Hybrid Brayton–Ericsson cycles. Initially, a numerical simulation was performed using a 1D, time-dependent, numerical model. Then a comparison was made with respect to the cooling power and the COP for different temperature spans. We showed that applying the Ericsson or the Hybrid Brayton–Ericsson cycle with an AMR, instead of the standard Brayton cycle, can increase the efficiency of the selected cooling device. Yet, in the case of the Ericsson cycle, the cooling power was decreased compared to the Hybrid and especially compared to the Brayton cycle. Next, an experimental analysis was carried out using a linear-type magnetic cooling device. Again, the Brayton, Ericsson and Hybrid Brayton–Ericsson cycles with an AMR were compared with respect to the cooling power and the COP for different temperature spans. The results of the numerical simulation were confirmed. The Hybrid Brayton–Ericsson cycle with an AMR showed the best performance if a no-load temperature span was considered as a criterion. -- Highlights: • New thermodynamic cycles with an active magnetic regenerator (AMR) are presented. • Three different thermodynamic cycles with an AMR were analyzed. • Numerical and experimental analyses were carried out. • The best overall performance was achieved with the Hybrid Brayton–Ericsson cycle. • With this cycle the temperature span of test device was increased by almost 10%

  6. Optimum design and thermodynamic analysis of a gas turbine and ORC combined cycle with recuperators

    International Nuclear Information System (INIS)

    Cao, Yue; Gao, Yike; Zheng, Ya; Dai, Yiping

    2016-01-01

    Highlights: • A GT-ORC combined cycle with recuperators was designed. • The effect of the ORC turbine inlet pressure on the combined cycle was examined. • Toluene was a more suitable working fluid for the GT-ORC combined cycle. • The GT-ORC combined cycle performed better than the GT-Rankine combined cycle. • The sensitivity analysis to the ambient temperature was completed. - Abstract: Gas turbines are widely used in distributed power generation because of their high efficiency, low pollution and low operational cost. To further utilize the waste heat from gas turbines, an organic Rankine cycle (ORC) was proposed as the bottoming cycle for gas turbines in this paper. Two recuperators were coupled with the combined cycle to increase the thermal efficiency, and aromatics were chosen as the working fluid for the bottoming cycle. This paper focused on the optimum design and thermodynamic analysis of the gas turbine and ORC (GT-ORC) combined cycle. Results showed that the net power and thermal efficiency of the ORC increased with the ORC turbine inlet pressure and achieved optimum values at a specific pressure based on the optimum criteria. Furthermore, compared with the GT-Rankine combined cycle, the GT-ORC combined cycle had better thermodynamic performance. Toluene was a more suitable working fluid for the GT-ORC combined cycle. Moreover, ambient temperature sensitivity simulations concluded that the GT-ORC combined cycle had a maximum thermal efficiency and the combined cycle net power was mainly determined by the topping gas turbine cycle.

  7. Thermodynamics

    CERN Document Server

    Fermi, Enrico

    1956-01-01

    Indisputably, this is a modern classic of science. Based on a course of lectures delivered by the author at Columbia University, the text is elementary in treatment and remarkable for its clarity and organization. Although it is assumed that the reader is familiar with the fundamental facts of thermometry and calorimetry, no advanced mathematics beyond calculus is assumed.Partial contents: thermodynamic systems, the first law of thermodynamics (application, adiabatic transformations), the second law of thermodynamics (Carnot cycle, absolute thermodynamic temperature, thermal engines), the entr

  8. Evaporative gas turbine cycles. A thermodynamic evaluation of their potential

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, P M

    1993-03-01

    The report presents a systematic method of thermodynamically evaluating different gas turbine cycles, treating the working fluids as ideal gases (c{sub p}=c{sub p}(T)). All models used to simulate different components in the cycles are presented in the report in detail and then connected in a computer program fully developed by the author. The report focuses on the theme of evaporative gas turbine cycles, in which low level heat is used to evaporate water into the compressed air stream between the compressor and recuperator. This leads to efficiency levels close to a comparable combined cycle but without the steam bottoming cycle. A parametric analysis has been conducted with the aim of deciding the best configuration of an evaporative cycle both for an uncooled expander and for a cooled expander. The model proposed to simulate the cooled expander is a combination between two existing models. (121 refs., 35 figs.,).

  9. Thermodynamic analysis of a novel integrated solar combined cycle

    International Nuclear Information System (INIS)

    Li, Yuanyuan; Yang, Yongping

    2014-01-01

    Highlights: • A novel ISCC scheme with two-stage DSG fields has been proposed and analyzed. • HRSG and steam turbine working parameters have been optimized to match the solar integration. • New scheme exhibits higher solar shares in the power output and solar-to-electricity efficiency. • Thermodynamic performances between new and reference systems have been investigated and compared. - Abstract: Integrated solar combined cycle (ISCC) systems have become more and more popular due to their high fuel and solar energy utilization efficiencies. Conventional ISCC systems with direct steam generation (DSG) have only one-stage solar input. A novel ISCC with DSG system has been proposed and analyzed in this paper. The new system consists two-stage solar input, which would significantly increase solar share in the total power output. Moreover, how and where solar energy is input into ISCC system would have impact on the solar and system overall efficiencies, which have been analyzed in the paper. It has been found that using solar heat to supply latent heat for vaporization of feedwater would be superior to that to be used for sensible heating purposes (e.g. Superheating steam). The study shows that: (1) producing both the high- and low-pressure saturated steam in the DSG trough collector could be an efficient way to improve process and system performance; (2) for a given live steam pressure, the optimum secondary and reheat steam conditions could be matched to reach the highest system thermal efficiency and net solar-to-electricity efficiency; (3) the net solar-to-electricity efficiency could reach up to 30% in the novel two-stage ISCC system, higher than that in the one-stage ISCC power plant; (4) compared with the conventional combined cycle gas turbine (CCGT) power system, lower stack temperature could be achieved, owing to the elimination of the approach-temperature-difference constraint, resulting in better thermal match in the heat recovery steam generator

  10. Optical cycle power meter

    DEFF Research Database (Denmark)

    2014-01-01

    A bicycle power meter for measuring power generated when riding a bicycle, the power meter comprising a position-sensitive radiation detector (409) attachable to a component of a crank set (404) of bicycle, and a radiation source (408) attachable to the component of the crank set and configured t...

  11. Comparative analysis of thermodynamic performance and optimization of organic flash cycle (OFC) and organic Rankine cycle (ORC)

    International Nuclear Information System (INIS)

    Lee, Ho Yong; Park, Sang Hee; Kim, Kyoung Hoon

    2016-01-01

    A comparative thermodynamic performance and optimization analysis of basic organic flash cycle (OFCB), organic flash cycle with two-phase expander (OFCT), and organic Rankine cycle (ORC) activated by low-temperature sensible energy is carried out in the subcritical pressure regions. The three substances of R245fa, R123, and o-xylene are considered as the working fluids. Effects of cycle type, working fluid, and evaporation and source temperatures are systemically investigated on the system performance such as net power production, thermal and exergy efficiencies, and exergy destruction ratios at each component of the systems. Results show that the cycle type or working fluid which shows optimum performance depends on the source temperature, and organic flash cycle shows a potential for efficient recovery of low grade energy source.

  12. A study on different thermodynamic cycle schemes coupled with a high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Qu, Xinhe; Yang, Xiaoyong; Wang, Jie

    2017-01-01

    Highlights: • The features of three different power generation schemes, including closed Brayton cycle, non-reheating combined cycle and reheating combined cycle, coupled with high temperature gas-cooled reactor (HTGR) were investigated and compared. • The effects and mechanism of reactor core outlet temperature, compression ratio and other key parameters over cycle characteristics were analyzed by the thermodynamic models.. • It is found that reheated combined cycle has the highest efficiency. Reactor outlet temperature and main steam parameters are key factors to improve the cycle’s performance. - Abstract: With gradual increase in reactor outlet temperature, the efficient power conversion technology has become one of developing trends of (very) high temperature gas-cooled reactors (HTGRs). In this paper, different cycle power generation schemes for HTGRs were systematically studied. Physical and mathematical models were established for these three cycle schemes: closed Brayton cycle, simple combined cycle, and reheated combined cycle. The effects and mechanism of key parameters such as reactor core outlet temperature, reactor core inlet temperature and compression ratio on the features of these cycles were analyzed. Then, optimization results were given with engineering restrictive conditions, including pinch point temperature differences. Results revealed that within the temperature range of HTGRs (700–900 °C), the reheated combined cycle had the highest efficiency, while the simple combined cycle had the lowest efficiency (900 °C). The efficiencies of the closed Brayton cycle, simple combined cycle and reheated combined cycle are 49.5%, 46.6% and 50.1%, respectively. These results provide insights on the different schemes of these cycles, and reveal the effects of key parameters on performance of these cycles. It could be helpful to understand and develop a combined cycle coupled with a high temperature reactor in the future.

  13. Effect of irreversible processes on the thermodynamic performance of open-cycle desiccant cooling cycles

    International Nuclear Information System (INIS)

    La, Dong; Li, Yong; Dai, Yanjun; Ge, Tianshu; Wang, Ruzhu

    2013-01-01

    Highlights: ► Effects of irreversible processes on the performance of desiccant cooling cycle are identified. ► The exergy destructions involved are classified by the properties of the individual processes. ► Appropriate indexes for thermodynamic evaluation are proposed based on thermodynamic analyses. - Abstract: Thermodynamic analyses of desiccant cooling cycle usually focus on the overall cycle performance in previous study. In this paper, the effects of the individual irreversible processes in each component on thermodynamic performance are analyzed in detail. The objective of this paper is to reveal the elemental features of the individual components, and to show their effects on the thermodynamic performance of the whole cycle in a fundamental way. Appropriate indexes for thermodynamic evaluation are derived based on the first and second law analyses. A generalized model independent of the connection of components is developed. The results indicate that as the effectiveness of the desiccant wheel increases, the cycle performance is increased principally due to the significant reduction in exergy carried out by exhaust air. The corresponding exergy destruction coefficient of the cycle with moderate performance desiccant wheel is decreased greatly to 3.9%, which is more than 50% lower than that of the cycle with low performance desiccant wheel. The effect of the heat source is similar. As the temperature of the heat source increases from 60 °C to 90 °C, the percentage of exergy destruction raised by exhaust air increases sharply from 5.3% to 21.8%. High heat exchanger effectiveness improves the cycle performance mainly by lowering the irreversibility of the heat exchanger, using less regeneration heat and pre-cooling the process air effectively

  14. Heat exchangers for high-temperature thermodynamic cycles

    International Nuclear Information System (INIS)

    Fraas, A.P.

    1975-01-01

    The special requirements of heat exchangers for high temperature thermodynamic cycles are outlined and discussed with particular emphasis on cost and thermal stress problems. Typical approaches that have been taken to a comprehensive solution intended to meet all of the many boundary conditions are then considered by examining seven typical designs including liquid-to-liquid heat exchangers for nuclear plants, a heater for a closed cycle gas turbine coupled to a fluidized bed coal combustion chamber, steam generators for nuclear plants, a fossil fuel-fired potassium boiler, and a potassium condenser-steam generator. (auth)

  15. Thermodynamic analysis of absorption refrigeration cycles using the second law of thermodynamics method

    Energy Technology Data Exchange (ETDEWEB)

    Aphornratana, S; Eames, I W [Sheffield Univ. (United Kingdom). Dept. of Mechanical and Process Engineering

    1995-05-01

    The paper provides an easy to follow description of the second law (of thermodynamics) method as applied to a single-effect absorption refrigerator cycle. Results are presented in a novel graphical format, which aids insight and understanding of those factors that most affect the performance of absorption refrigerators, and which in turn provides strong indicators for the direction of future research. A novel method of calculating the entropy of lithium bromide solutions is offered. (author)

  16. Thermodynamic analysis of the advanced zero emission power plant

    Directory of Open Access Journals (Sweden)

    Kotowicz Janusz

    2016-03-01

    Full Text Available The paper presents the structure and parameters of advanced zero emission power plant (AZEP. This concept is based on the replacement of the combustion chamber in a gas turbine by the membrane reactor. The reactor has three basic functions: (i oxygen separation from the air through the membrane, (ii combustion of the fuel, and (iii heat transfer to heat the oxygen-depleted air. In the discussed unit hot depleted air is expanded in a turbine and further feeds a bottoming steam cycle (BSC through the main heat recovery steam generator (HRSG. Flue gas leaving the membrane reactor feeds the second HRSG. The flue gas consist mainly of CO2 and water vapor, thus, CO2 separation involves only the flue gas drying. Results of the thermodynamic analysis of described power plant are presented.

  17. Thermodynamic analysis and conceptual design for partial coal gasification air preheating coal-fired combined cycle

    Science.gov (United States)

    Xu, Yue; Wu, Yining; Deng, Shimin; Wei, Shirang

    2004-02-01

    The partial coal gasification air pre-heating coal-fired combined cycle (PGACC) is a cleaning coal power system, which integrates the coal gasification technology, circulating fluidized bed technology, and combined cycle technology. It has high efficiency and simple construction, and is a new selection of the cleaning coal power systems. A thermodynamic analysis of the PGACC is carried out. The effects of coal gasifying rate, pre-heating air temperature, and coal gas temperature on the performances of the power system are studied. In order to repower the power plant rated 100 MW by using the PGACC, a conceptual design is suggested. The computational results show that the PGACC is feasible for modernizing the old steam power plants and building the new cleaning power plants.

  18. Perform Thermodynamics Measurements on Fuel Cycle Case Study Systems

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Leigh R. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-09-01

    This document was prepared to meet FCR&D level 3 milestone M3FT-14IN0304022, “Perform Thermodynamics Measurements on Fuel Cycle Case Study Systems.” This work was carried out under the auspices of the Thermodynamics and Kinetics FCR&D work package. This document reports preliminary work in support of determining the thermodynamic parameters for the ALSEP process. The ALSEP process is a mixed extractant system comprised of a cation exchanger 2-ethylhexyl-phosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) and a neutral solvating extractant N,N,N’,N’-tetraoctyldiglycolamide (TODGA). The extractant combination produces complex organic phase chemistry that is challenging for traditional measurement techniques. To neutralize the complexity, temperature dependent solvent extraction experiments were conducted with neat TODGA and scaled down concentrations of the ALSEP formulation to determine the enthalpies of extraction for the two conditions. A full set of thermodynamic data for Eu, Am, and Cm extraction by TODGA from 3.0 M HNO3 is reported. These data are compared to previous extraction results from a 1.0 M HNO3 aqueous medium, and a short discussion of the mixed HEH[EHP]/TODGA system results is offered.

  19. An optimization method for gas refrigeration cycle based on the combination of both thermodynamics and entransy theory

    International Nuclear Information System (INIS)

    Chen, Qun; Xu, Yun-Chao; Hao, Jun-Hong

    2014-01-01

    Highlights: • An optimization method for practical thermodynamic cycle is developed. • The entransy-based heat transfer analysis and thermodynamic analysis are combined. • Theoretical relation between system requirements and design parameters is derived. • The optimization problem can be converted into conditional extremum problem. • The proposed method provides several useful optimization criteria. - Abstract: A thermodynamic cycle usually consists of heat transfer processes in heat exchangers and heat-work conversion processes in compressors, expanders and/or turbines. This paper presents a new optimization method for effective improvement of thermodynamic cycle performance with the combination of entransy theory and thermodynamics. The heat transfer processes in a gas refrigeration cycle are analyzed by entransy theory and the heat-work conversion processes are analyzed by thermodynamics. The combination of these two analysis yields a mathematical relation directly connecting system requirements, e.g. cooling capacity rate and power consumption rate, with design parameters, e.g. heat transfer area of each heat exchanger and heat capacity rate of each working fluid, without introducing any intermediate variable. Based on this relation together with the conditional extremum method, we theoretically derive an optimization equation group. Simultaneously solving this equation group offers the optimal structural and operating parameters for every single gas refrigeration cycle and furthermore provides several useful optimization criteria for all the cycles. Finally, a practical gas refrigeration cycle is taken as an example to show the application and validity of the newly proposed optimization method

  20. Biological catalysis of the hydrological cycle: life's thermodynamic function

    Science.gov (United States)

    Michaelian, K.

    2011-01-01

    Darwinian theory depicts life as being overwhelmingly consumed by a fight for survival in a hostile environment. However, from a thermodynamic perspective, life is a dynamic out of equilibrium process, stabilizing and coevolving in concert with its abiotic environment. The living component of the biosphere on the surface of the Earth of greatest biomass, the plants and cyanobacteria, are involved in the transpiration of a vast amount of water. Transpiration is part of the global water cycle, and it is this cycle that distinguishes Earth from its apparently life barren neighboring planets, Venus and Mars. The dissipation of sunlight into heat by organic molecules in the biosphere and its coupling to the water cycle (as well as other abiotic processes), is by far the greatest entropy producing process occurring on Earth. Life, from this perspective, can be viewed as performing an important thermodynamic function; acting as a dynamic catalyst by aiding irreversible abiotic process such as the water cycle, hurricanes, and ocean and wind currents to produce entropy. The role of animals in this view is that of unwitting but dedicated servants of the plants and cyanobacteria, helping them to grow and to spread into initially inhospitable areas.

  1. FINITE TIME THERMODYNAMIC MODELING AND ANALYSIS FOR AN IRREVERSIBLE ATKINSON CYCLE

    Directory of Open Access Journals (Sweden)

    Yanlin Ge

    2010-01-01

    Full Text Available Performance of an air-standard Atkinson cycle is analyzed by using finite-time thermodynamics. The irreversible cycle model which is more close to practice is founded. In this model, the non-linear relation between the specific heats of working fluid and its temperature, the friction loss computed according to the mean velocity of the piston, the internal irreversibility described by using the compression and expansion efficiencies, and heat transfer loss are considered. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle are derived by detailed numerical examples. Moreover, the effects of internal irreversibility, heat transfer loss and friction loss on the cycle performance are analyzed. The results obtained in this paper may provide guidelines for the design of practical internal combustion engines.

  2. Ideal thermodynamic processes of oscillatory-flow regenerative engines will go to ideal stirling cycle?

    Science.gov (United States)

    Luo, Ercang

    2012-06-01

    This paper analyzes the thermodynamic cycle of oscillating-flow regenerative machines. Unlike the classical analysis of thermodynamic textbooks, the assumptions for pistons' movement limitations are not needed and only ideal flowing and heat transfer should be maintained in our present analysis. Under such simple assumptions, the meso-scale thermodynamic cycles of each gas parcel in typical locations of a regenerator are analyzed. It is observed that the gas parcels in the regenerator undergo Lorentz cycle in different temperature levels, whereas the locus of all gas parcels inside the regenerator is the Ericson-like thermodynamic cycle. Based on this new finding, the author argued that ideal oscillating-flow machines without heat transfer and flowing losses is not the Stirling cycle. However, this new thermodynamic cycle can still achieve the same efficiency of the Carnot heat engine and can be considered a new reversible thermodynamic cycle under two constant-temperature heat sinks.

  3. Optimization of powered Stirling heat engine with finite speed thermodynamics

    International Nuclear Information System (INIS)

    Ahmadi, Mohammad H.; Ahmadi, Mohammad Ali; Pourfayaz, Fathollah; Bidi, Mokhtar; Hosseinzade, Hadi; Feidt, Michel

    2016-01-01

    Highlights: • Based on finite speed method and direct method, the optimal performance is investigated. • The effects of major parameters on the optimal performance are investigated. • The accuracy of the results was compared with previous works. - Abstract: Popular thermodynamic analyses including finite time thermodynamic analysis was lately developed based upon external irreversibilities while internal irreversibilities such as friction, pressure drop and entropy generation were not considered. The aforementioned disadvantage reduces the reliability of the finite time thermodynamic analysis in the design of an accurate Stirling engine model. Consequently, the finite time thermodynamic analysis could not sufficiently satisfy researchers for implementing in design and optimization issues. In this study, finite speed thermodynamic analysis was employed instead of finite time thermodynamic analysis for studying Stirling heat engine. The finite speed thermodynamic analysis approach is based on the first law of thermodynamics for a closed system with finite speed and the direct method. The effects of heat source temperature, regenerating effectiveness, volumetric ratio, piston stroke as well as rotational speed are included in the analysis. Moreover, maximum output power in optimal rotational speed was calculated while pressure losses in the Stirling engine were systematically considered. The result reveals the accuracy and the reliability of the finite speed thermodynamic method in thermodynamic analysis of Stirling heat engine. The outcomes can help researchers in the design of an appropriate and efficient Stirling engine.

  4. Energy Conversion Alternatives Study (ECAS), Westinghouse phase 1. Volume 4: Open recuperated and bottomed gas turbine cycles. [performance prediction and energy conversion efficiency of gas turbines in electric power plants (thermodynamic cycles)

    Science.gov (United States)

    Amos, D. J.; Grube, J. E.

    1976-01-01

    Open-cycle recuperated gas turbine plant with inlet temperatures of 1255 to 1644 K (1800 to 2500 F) and recuperators with effectiveness values of 0, 70, 80 and 90% are considered. A 1644 K (2500 F) gas turbine would have a 33.5% plant efficiency in a simple cycle, 37.6% in a recuperated cycle and 47.6% when combined with a sulfur dioxide bottomer. The distillate burning recuperated plant was calculated to produce electricity at a cost of 8.19 mills/MJ (29.5 mills/kWh). Due to their low capital cost $170 to 200 $/kW, the open cycle gas turbine plant should see duty for peaking and intermediate load duty.

  5. 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.

  6. Thermodynamic assessment of a wind turbine based combined cycle

    International Nuclear Information System (INIS)

    Rabbani, M.; Dincer, I.; Naterer, G.F.

    2012-01-01

    Combined cycles use the exhaust gases released from a Gas Turbine (GT). Approximately 30–40% of the turbine shaft work is typically used to drive the Compressor. The present study analyzes a system that couples a Wind Turbine (WT) with a combined cycle. It demonstrates how a WT can be used to supply power to the Compressor in the GT cycle and pump fluid through a reheat Rankine cycle, in order to increase the overall power output. Three different configurations are discussed, namely high penetration, low penetration and wind power addition. In the case of a low electricity demand and high penetration configuration, extra wind power is used to compress air which can then be used in the low penetration configuration. During a high load demand, all the wind power is used to drive the pump and compressor and if required additional compressed air is supplied by a storage unit. The analysis shows that increasing the combustion temperature reduces the critical velocity and mass flow rate. Increases in wind speed reduce both energy and exergy efficiency of the overall system. -- Highlights: ► This study analyzes a system that couples a wind turbine with a combined power generation cycle. ► Surplus wind power is used to compress air, which is then stored and used at a later time. ► Increasing the pressure ratio will reduce the work ratio between the Rankine and Brayton cycles. ► A higher combustion temperature will increase the net work output, as well as the system energy and exergy efficiencies.

  7. Thermodynamic analysis of an organic rankine cycle using a tubular solar cavity receiver

    International Nuclear Information System (INIS)

    Loni, R.; Kasaeian, A.B.; Mahian, O.; Sahin, A.Z.

    2016-01-01

    Highlights: • A non-regenerative Organic Rankine Cycle has been analyzed. • R113, R601, R11, R141b, Ethanol and Methanol were used as the working fluid. • A parabolic dish concentrator with a square prismatic cavity receiver was used. • Thermal efficiency, second law efficiency, and net power output were analyzed. - Abstract: In this study, a non-regenerative Organic Rankine Cycle (ORC) has been thermodynamically analyzed under superheated conditions, constant evaporator pressure of 2.5 MPa, and condenser temperature of 300 K. R113, R601, R11, R141b, Ethanol and Methanol were employed as the working fluid. A parabolic dish concentrator with a square prismatic tubular cavity receiver was used as the heat source of the ORC system. The effects of the tube diameter, the cavity depth, and the solar irradiation on the thermodynamic performance of the selected working fluid were investigated. Some thermodynamic parameters were analyzed in this study. These thermodynamic parameters included the thermal efficiency, second law efficiency, total irreversibility, availability ratio, mass flow rate, and net power output. The results showed that, among the selected working fluids, methanol had the highest thermal efficiency, net power output, second law efficiency, and availability ratio in the range of turbine inlet temperature (TIT) considered. On the other hand, methanol had the smallest total irreversibility in the same range of TIT. The results showed also that mass flow rate and consequently the net power output increased for higher solar irradiation, smaller tube diameter, and for the case of cubical cavity receiver (i.e. cavity depth h equal to the receiver aperture side length a).

  8. Exergetic comparison of two different cooling technologies for the power cycle of a thermal power plant

    International Nuclear Information System (INIS)

    Blanco-Marigorta, Ana M.; Victoria Sanchez-Henriquez, M.; Pena-Quintana, Juan A.

    2011-01-01

    Exergetic analysis is without any doubt a powerful tool for developing, evaluating and improving an energy conversion system. In the present paper, two different cooling technologies for the power cycle of a 50 MWe solar thermal power plant are compared from the exergetic viewpoint. The Rankine cycle design is a conventional, single reheat design with five closed and one open extraction feedwater heaters. The software package GateCycle is used for the thermodynamic simulation of the Rankine cycle model. The first design configuration uses a cooling tower while the second configuration uses an air cooled condenser. With this exergy analysis we identify the location, magnitude and the sources or thermodynamic inefficiencies in this thermal system. This information is very useful for improving the overall efficiency of the power system and for comparing the performance of both technologies.

  9. An integrated optimization for organic Rankine cycle based on entransy theory and thermodynamics

    International Nuclear Information System (INIS)

    Li, Tailu; Fu, Wencheng; Zhu, Jialing

    2014-01-01

    The organic Rankine cycle has been one of the essential heat-work conversion technologies nowadays. Lots of effectual optimization methods are focused on the promotion of the system efficiency, which are mainly relied on engineering experience and numerical simulations rather than theoretical analysis. A theoretical integrated optimization method was established based on the entransy theory and thermodynamics, with the ratio of the net power output to the ratio of the total thermal conductance to the thermal conductance in the condenser as the objective function. The system parameters besides the optimal pinch point temperature difference were obtained. The results show that the mass flow rate of the working fluid is inversely proportional to the evaporating temperature. An optimal evaporating temperature maximizes the net power output, and the maximal net power output corresponds to the maximal entransy loss and the change points of the heat source outlet temperature and the change rates for the entropy generation and the entransy dissipation. Moreover, the net power output and the total thermal conductance are inversely proportional to the pinch point temperature difference, contradicting with each other. Under the specified condition, the optimal operating parameters are ascertained, with the optimal pinch point temperature difference of 5 K. - Highlights: • We establish an integrated optimization model for organic Rankine cycle. • The model combines the entransy theory with thermodynamics. • The maximal net power output corresponds to the maximal entransy loss. • The pinch point temperature difference is optimized to be 5 K

  10. Thermodynamic analysis of a combined gas turbine, ORC cycle and absorption refrigeration for a CCHP system

    International Nuclear Information System (INIS)

    Mohammadi, Amin; Kasaeian, Alibakhsh; Pourfayaz, Fathollah; Ahmadi, Mohammad Hossein

    2017-01-01

    Highlights: • Thermodynamic analysis of a hybrid CCHP system. • Sensitivity analysis is performed on the most important parameters of the system. • Pressure ratio and gas turbine inlet temperature are the most effective parameters. - Abstract: Hybrid power systems are gained more attention due to their better performance and higher efficiency. Widespread use of these systems improves environmental situation as they reduce the amount of fossil fuel consumption. In this paper a hybrid system composed of a gas turbine, an ORC cycle and an absorption refrigeration cycle is proposed as a combined cooling, heating and power system for residential usage. Thermodynamic analysis is applied on the system. Also a parametric analysis is carried out to investigate the effect of different parameters on the system performance and output cooling, heating and power. The results show that under design conditions, the proposed plant can produce 30 kW power, 8 kW cooling and almost 7.2 ton hot water with an efficiency of 67.6%. Moreover, parametric analysis shows that pressure ratio and gas turbine inlet temperature are the most important and influential parameters. After these two, ORC turbine inlet temperature is the most effective parameter as it can change both net output power and energy efficiency of the system.

  11. Nonlinear Thermodynamic Analysis and Optimization of a Carnot Engine Cycle

    Directory of Open Access Journals (Sweden)

    Michel Feidt

    2016-06-01

    Full Text Available As part of the efforts to unify the various branches of Irreversible Thermodynamics, the proposed work reconsiders the approach of the Carnot engine taking into account the finite physical dimensions (heat transfer conductances and the finite speed of the piston. The models introduce the irreversibility of the engine by two methods involving different constraints. The first method introduces the irreversibility by a so-called irreversibility ratio in the entropy balance applied to the cycle, while in the second method it is emphasized by the entropy generation rate. Various forms of heat transfer laws are analyzed, but most of the results are given for the case of the linear law. Also, individual cases are studied and reported in order to provide a simple analytical form of the results. The engine model developed allowed a formal optimization using the calculus of variations.

  12. Thermodynamic performance evaluation of transcritical carbon dioxide refrigeration cycle integrated with thermoelectric subcooler and expander

    International Nuclear Information System (INIS)

    Dai, Baomin; Liu, Shengchun; Zhu, Kai; Sun, Zhili; Ma, Yitai

    2017-01-01

    New configurations of transcritical CO_2 refrigeration cycle combined with a thermoelectric (TE) subcooler and an expander (TES+EXP_H_M and TES+EXP_M_L) are proposed. The expander can operate between the high-pressure to the vessel pressure, or from vessel pressure to evaporation pressure. A power system is utilized to balance and supply power to thermoelectric subcooler and compressor. Thermodynamic performance optimizations and analyses are presented. Comparisons are carried out with the BASE, EXP_H_M, EXP_M_L, and TES cycles. The results show that the coefficient of performance (COP) improvement is more notable when the expander is installed between the liquid receiver and the evaporator. Maximum COP is obtained for the new cycles with a simultaneous optimization of discharge pressure and subcooling temperature. The new proposed TES+EXP_M_L cycle shows an excellent and steady performance than other cycles. It operates not only with the highest COP, but also the lowest discharge pressure. Under the working conditions of high gas cooler outlet temperature or low evaporation temperature, the merits of COP improvement and discharge pressure reduction are more prominent. The new cycle is more suitable for the hot regions where the CO_2 can not be sufficiently subcooled or the refrigerated space operates at low evaporation temperature. - Highlights: • New configurations of transcritical CO_2 refrigeration cycle are proposed. • New cycles are optimized and compared with other cycles. • The position of expander has an evident influence on the performance of CO_2 cycle. • TES+EXP_M_L cycle shows the highest COP and lowest discharge pressure. • The range of application for the TES+EXP_M_L cycle is recommended.

  13. Progress in Finite Time Thermodynamic Studies for Internal Combustion Engine Cycles

    Directory of Open Access Journals (Sweden)

    Yanlin Ge

    2016-04-01

    Full Text Available On the basis of introducing the origin and development of finite time thermodynamics (FTT, this paper reviews the progress in FTT optimization for internal combustion engine (ICE cycles from the following four aspects: the studies on the optimum performances of air standard endoreversible (with only the irreversibility of heat resistance and irreversible ICE cycles, including Otto, Diesel, Atkinson, Brayton, Dual, Miller, Porous Medium and Universal cycles with constant specific heats, variable specific heats, and variable specific ratio of the conventional and quantum working fluids (WFs; the studies on the optimum piston motion (OPM trajectories of ICE cycles, including Otto and Diesel cycles with Newtonian and other heat transfer laws; the studies on the performance limits of ICE cycles with non-uniform WF with Newtonian and other heat transfer laws; as well as the studies on the performance simulation of ICE cycles. In the studies, the optimization objectives include work, power, power density, efficiency, entropy generation rate, ecological function, and so on. The further direction for the studies is explored.

  14. Thermodynamic analysis of a directly heated oxyfuel supercritical power system

    International Nuclear Information System (INIS)

    Chowdhury, A.S.M. Arifur; Bugarin, Luz; Badhan, Antara; Choudhuri, Ahsan; Love, Norman

    2016-01-01

    Highlights: • A thermodynamic analysis of a supercritical power cycle is presented. • The supercritical power cycle is modeled using ASPEN HYSYS®. • A liquid methane and oxygen feed system is more efficient than a gaseous system. • CO_2 recirculated in gas form is 10.6% more efficient than when in liquid form. • Commercially available technologies permit liquid feed system delivery. - Abstract: Directly heated supercritical oxy-fuel gas turbines have potential to provide a higher thermal efficiency and lower pollutant emissions compared to current gas turbine systems. Motivated by the advantages of an oxyfuel-based directly heated supercritical power system, this paper presents an analysis of different operating conditions using ASPEN HYSYS®. This study first investigates the efficiency of gaseous or liquid methane and oxygen feed systems. T-s and P-v diagrams are generated and compared to each other to determine which is more efficient. The analysis revealed that the entropy generated during the combustion process for a liquid feed system is approximately three times higher than when methane and oxygen are compressed in gaseous form and delivered to the combustor and burned. To mitigate the high temperatures (3300 K) of the methane and oxygen combustion reaction, carbon dioxide is recirculated. For this portion of the system, the use of gaseous and liquid carbon dioxide recirculation loops and their corresponding efficiencies are determined. The investigation shows that the system yielded a higher net efficiency of 55.1% when gaseous carbon dioxide is recirculated as a diluent with liquid methane and oxygen delivery to the combustor.

  15. Investigation of thermodynamic cycle for generic 1200 MW{sub el} pressure channel reactor with nuclear steam superheat

    Energy Technology Data Exchange (ETDEWEB)

    Vincze, A.; Sidawi, K.; Abdullah, R.; Baldock, M.; Saltanov, E.; Pioro, I., E-mail: andrei.vincze@uoit.net, E-mail: khalil.sidawi@uoit.net, E-mail: rand.abdullah@uoit.net, E-mail: matthew.baldock@uoit.net, E-mail: eugene.saltanov@uoit.ca, E-mail: igor.pioro@uoit.ca [Univ. of Ontario Inst. of Tech., Oshawa, ON (Canada)

    2014-07-01

    Current Nuclear Power Plants (NPPs) play a significant role in energy production around the world. All NPPs operating today employ a Rankine steam cycle for the conversion of thermal power to electricity. This paper will examine the steam cycle arrangement an experimental pressure channel reactor using Nuclear Steam Superheat (NSS) and compare it to two advanced reactor designs, the Advanced CANDU Reactor 1000 (ACR-1000) and the Advanced Boiling Water Reactor (ABWR) designs. The thermodynamic cycle layout and thermal efficiencies of the three reactor types will be discussed. (author)

  16. Applicability of the minimum entropy generation method for optimizing thermodynamic cycles

    Institute of Scientific and Technical Information of China (English)

    Cheng Xue-Tao; Liang Xin-Gang

    2013-01-01

    Entropy generation is often used as a figure of merit in thermodynamic cycle optimizations.In this paper,it is shown that the applicability of the minimum entropy generation method to optimizing output power is conditional.The minimum entropy generation rate and the minimum entropy generation number do not correspond to the maximum output power when the total heat into the system of interest is not prescribed.For the cycles whose working medium is heated or cooled by streams with prescribed inlet temperatures and prescribed heat capacity flow rates,it is theoretically proved that both the minimum entropy generation rate and the minimum entropy generation number correspond to the maximum output power when the virtual entropy generation induced by dumping the used streams into the environment is considered.However,the minimum principle of entropy generation is not tenable in the case that the virtual entropy generation is not included,because the total heat into the system of interest is not fixed.An irreversible Carnot cycle and an irreversible Brayton cycle are analysed.The minimum entropy generation rate and the minimum entropy generation number do not correspond to the maximum output power if the heat into the system of interest is not prescribed.

  17. Applicability of the minimum entropy generation method for optimizing thermodynamic cycles

    International Nuclear Information System (INIS)

    Cheng Xue-Tao; Liang Xin-Gang

    2013-01-01

    Entropy generation is often used as a figure of merit in thermodynamic cycle optimizations. In this paper, it is shown that the applicability of the minimum entropy generation method to optimizing output power is conditional. The minimum entropy generation rate and the minimum entropy generation number do not correspond to the maximum output power when the total heat into the system of interest is not prescribed. For the cycles whose working medium is heated or cooled by streams with prescribed inlet temperatures and prescribed heat capacity flow rates, it is theoretically proved that both the minimum entropy generation rate and the minimum entropy generation number correspond to the maximum output power when the virtual entropy generation induced by dumping the used streams into the environment is considered. However, the minimum principle of entropy generation is not tenable in the case that the virtual entropy generation is not included, because the total heat into the system of interest is not fixed. An irreversible Carnot cycle and an irreversible Brayton cycle are analysed. The minimum entropy generation rate and the minimum entropy generation number do not correspond to the maximum output power if the heat into the system of interest is not prescribed. (general)

  18. The trigeneration cycle as a way to create multipurpose stationary power plants based on conversion of aeroderivative turbofan engines

    Science.gov (United States)

    Varaksin, A. Yu.; Arbekov, A. N.; Inozemtsev, A. A.

    2014-10-01

    A schematic cycle is considered, and thermodynamic analysis is performed to substantiate the possibility of creating multipurpose industrial power plants, operating on a trigeneration cycle, based on production-type turbofan engines.

  19. Analysis of engineering cycles thermodynamics and fluid mechanics series

    CERN Document Server

    Haywood, R W

    1980-01-01

    Analysis of Engineering Cycles, Third Edition, deals principally with an analysis of the overall performance, under design conditions, of work-producing power plants and work-absorbing refrigerating and gas-liquefaction plants, most of which are either cyclic or closely related thereto. The book is organized into two parts, dealing first with simple power and refrigerating plants and then moving on to more complex plants. The principal modifications in this Third Edition arise from the updating and expansion of material on nuclear plants and on combined and binary plants. In view of increased

  20. Study on the supercritical CO2 power cycles for landfill gas firing gas turbine bottoming cycle

    International Nuclear Information System (INIS)

    Kim, Min Seok; Ahn, Yoonhan; Kim, Beomjoo; Lee, Jeong Ik

    2016-01-01

    In this paper, a comparison of nine supercritical carbon dioxide (S-CO 2 ) bottoming power cycles in conjunction with a topping cycle of landfill gas (LFG) fired 5MWe gas turbine is presented. For the comparison purpose, a sensitivity study of the cycle design parameters for nine different cycles was conducted and each cycle thermodynamic performance is evaluated. In addition, the cycle performance evaluation dependency on the compressor inlet temperature variation is performed to investigate how S-CO 2 cycles sensitive to the heat sink temperature variation. Furthermore, the development of new S-CO 2 cycle layouts is reported and the suggested cycles' performances are compared to the existing cycle layouts. It was found that a recompression cycle is not suitable for the bottoming cycle application, but a partial heating cycle has relatively higher net produced work with a simple layout and small number of components. Although a dual heated and flow split cycle has the highest net produced work, it has disadvantages of having numerous components and complex process which requires more sophisticated operational strategies. This study identified that the recuperation process is much more important than the intercooling process to the S-CO 2 cycle design for increasing the thermal efficiency and the net produced work point of view. - Highlights: • Study of nine S-CO 2 power cycle layouts for a small scale landfill gas power generation application. • Development of new S-CO 2 cycle layouts. • Sensitivity analysis of S-CO 2 cycles to evaluate and compare nine cycles' performances.

  1. Power cycles with ammonia-water mixtures as working fluid

    Energy Technology Data Exchange (ETDEWEB)

    Thorin, Eva

    2000-05-01

    It is of great interest to improve the efficiency of power generating processes, i.e. to convert more of the energy in the heat source to power. This is favorable from an environmental point of view and can also be an economic advantage. To use an ammonia-water mixture instead of water as working fluid is a possible way to improve the efficiency of steam turbine processes. This thesis includes studies of power cycles with ammonia-water mixtures as working fluid utilizing different kinds of heat sources for power and heat generation. The thermophysical properties of the mixture are also studied. They play an important role in the calculations of the process performance and for the design of its components, such as heat exchangers. The studies concern thermodynamic simulations of processes in applications suitable for Swedish conditions. Available correlations for the thermophysical properties are compared and their influence on simulations and heat exchanger area predictions is investigated. Measurements of ammonia-water mixture viscosities using a vibrating wire viscometer are also described. The studies performed show that power cycles with ammonia-water mixtures as the working fluid are well suited for utilization of waste heat from industry and from gas engines. The ammonia-water power cycles can give up to 32 % more power in the industrial waste heat application and up to 54 % more power in the gas engine bottoming cycle application compared to a conventional Rankine steam cycle. However, ammonia-water power cycles in small direct-fired biomass-fueled cogeneration plants do not show better performance than a conventional Rankine steam cycle. When different correlations for the thermodynamic properties are used in simulations of a simple ammonia-water power cycle the difference in efficiency is not larger than 4 %, corresponding to about 1.3 percentage points. The differences in saturation properties between the correlations are, however, considerable at high

  2. New concepts for organic Rankine cycle power systems

    OpenAIRE

    Casati, E.I.M.

    2014-01-01

    Energy provision is one of the major challenges for the Human Society, and it is increasingly clear that the current production/consumption model is not sustainable. The envisaged energy system is smarter, more decentralised and integrated. Energy conversion systems based on the organic Rankine thermodynamic cycle (ORC) have the potential to play a major role in this framework, being one of the most proven solutions for the exploitation of external thermal sources in the power-output range fr...

  3. Optimization of the triple-pressure combined cycle power plant

    Directory of Open Access Journals (Sweden)

    Alus Muammer

    2012-01-01

    Full Text Available The aim of this work was to develop a new system for optimization of parameters for combined cycle power plants (CCGTs with triple-pressure heat recovery steam generator (HRSG. Thermodynamic and thermoeconomic optimizations were carried out. The objective of the thermodynamic optimization is to enhance the efficiency of the CCGTs and to maximize the power production in the steam cycle (steam turbine gross power. Improvement of the efficiency of the CCGT plants is achieved through optimization of the operating parameters: temperature difference between the gas and steam (pinch point P.P. and the steam pressure in the HRSG. The objective of the thermoeconomic optimization is to minimize the production costs per unit of the generated electricity. Defining the optimal P.P. was the first step in the optimization procedure. Then, through the developed optimization process, other optimal operating parameters (steam pressure and condenser pressure were identified. The developed system was demonstrated for the case of a 282 MW CCGT power plant with a typical design for commercial combined cycle power plants. The optimized combined cycle was compared with the regular CCGT plant.

  4. Ultimate refrigerating conditions, behavior turning and a thermodynamic analysis for absorption–compression hybrid refrigeration cycle

    International Nuclear Information System (INIS)

    Zheng Danxing; Meng Xuelin

    2012-01-01

    Highlights: ► Two novel fundamental concepts of the absorption refrigeration cycle were proposed. ► The interaction mechanism of compressor pressure increasing with other key-parameters was investigated. ► A set of optimal operating condition of hybrid refrigeration cycle was found. ► A simulation and investigation for R134a-DMF hybrid refrigeration cycle was performed. - Abstract: The absorption–compression hybrid refrigeration cycle has been considered as an effective approach to reduce the mechanical work consumption by using low-grade heat, such as solar energy. This work aims at studying the thermodynamic mechanism of the hybrid refrigeration cycle. Two fundamental concepts have been proposed, which are the ultimate refrigerating temperature (or the ultimate temperature lift) and the behavior turning. On the basis of that, the interaction mechanism of compressor pressure increasing with other key-parameters and the impact of compressor pressure increasing on the cycle performance have been investigated. The key-parameters include the concentration difference, the circulation ratio of working fluid, etc. The work points out that the hybrid refrigeration cycle performance varies with the change of compressor outlet pressure and depends on which one achieves dominance in the hybrid refrigeration cycle, the absorption sub-system or the compression sub-system. The behavior turning point during parameters changing corresponds to a maximum value of the heat powered coefficient of performance. In this case, the hybrid refrigeration cycle performance is optimal because the low-grade heat utilization is the most effective. In addition, to validate the theoretical analysis, a solar hybrid refrigeration cycle with R134a–DMF as working pair was simulated. The Peng–Robinson equation of state was adopted to calculate thermophysical properties when the reliability assessment of the prediction models on the available literature data of R134a–DMF system had been

  5. Investigating the effect of several thermodynamic parameters on exergy destruction in components of a tri-generation cycle

    International Nuclear Information System (INIS)

    Salehzadeh, A.; Khoshbakhti Saray, R.; JalaliVahid, D.

    2013-01-01

    Multiple energy generating cycles such as tri-generation cycles, which produce heat and cold in addition to power through burning of a primary fuel, have increasingly been used in recent decades. On the other hand, advanced exergy analysis of thermodynamic systems by splitting exergy destruction into endogenous and exogenous parts identifies internal irreversibilities of each of the components and the effect of these irreversibilities on the performance of other components. Therefore, main sources of exergy destruction in cycles can be highlighted and useful recommendations in order to improve the performance of thermodynamic cycles can be presented. In the present work, a tri-generation cycle with 100 MW power production, 70 MW heat and 9 MW cooling capacity is considered. For this tri-generation cycle, effects of various thermodynamic parameters on the amount of endogenous and exogenous exergy destructions, exergy loss and the amount of fuel consumption, are investigated. The results indicate that, increasing compressor pressure ratio, pre-heater outlet temperature and excess air leads to better combustion and lower exergy loss and fuel consumption. Increasing the mass flow rate of steam generator, while keeping the cycle outlet temperature constant and considering cooling capacity variable, lead to increase the first- and second-law efficiencies of the cycle. - Highlights: ► Advanced exergy analysis is used to analyze a tri-generation cycle. ► Increasing compressor pressure ratio leads to lower exergy loss and fuel consumption. ► Exergy loss is lowered by increasing pre-heater outlet temperature. ► Increasing the air flow rate of the cycle improves the performance of the cycle

  6. Gas turbine cooling modeling - Thermodynamic analysis and cycle simulations

    Energy Technology Data Exchange (ETDEWEB)

    Jordal, Kristin

    1999-02-01

    Considering that blade and vane cooling are a vital point in the studies of modern gas turbines, there are many ways to include cooling in gas turbine models. Thermodynamic methods for doing this are reviewed in this report, and, based on some of these methods, a number of model requirements are set up and a Cooled Gas Turbine Model (CGTM) for design-point calculations of cooled gas turbines is established. Thereafter, it is shown that it is possible to simulate existing gas turbines with the CGTM. Knowledge of at least one temperature in the hot part of the turbine (TET, TRIT or possibly TIT) is found to be vital for a complete heat balance over the turbine. The losses, which are caused by the mixing of coolant and main flow, are in the CGTM considered through a polytropic efficiency reduction factor S. Through the study of S, it can be demonstrated that there is more to gain from coolant reduction in a small and/or old turbine with poor aerodynamics, than there is to gain in a large, modern turbine, where the losses due to interaction between coolant and main flow are, relatively speaking, small. It is demonstrated, at the design point (TET=1360 deg C, {pi}=20) for the simple-cycle gas turbine, that heat exchanging between coolant and fuel proves to have a large positive impact on cycle efficiency, with an increase of 0.9 percentage points if all of the coolant passes through the heat exchanger. The corresponding improvement for humidified coolant is 0.8 percentage points. A design-point study for the HAT cycle shows that if all of the coolant is extracted after the humidification tower, there is a decrease in coolant requirements of 7.16 percentage points, from 19.58% to 12.52% of the compressed air, and an increase in thermal efficiency of 0.46 percentage points, from 53.46% to 53.92%. Furthermore, it is demonstrated with a TET-parameter variation, that the cooling of a simple-cycle gas turbine with humid air can have a positive effect on thermal efficiency

  7. Thermodynamic performance comparison between ORC and Kalina cycles for multi-stream waste heat recovery

    International Nuclear Information System (INIS)

    Wang, Yufei; Tang, Qikui; Wang, Mengying; Feng, Xiao

    2017-01-01

    Highlights: • Comparison between ORC and Kalina cycles (KC) for multi-stream waste heat recovery. • Divide waste heat into straight, convex and concave based on its composite curve. • Use heat ratio and temperature of the most point to show the feature of waste heat. • KC is suitable for straight and most concave heat, while ORC for convex one. - Abstract: Organic Rankine cycle (ORC) and Kalina cycle are the main technologies to recover waste heat for power generation. Up to now, many works dealing with the thermodynamic performance comparison between ORC and Kalina cycles are available, but these studies considered for heat recovery from a single heat source or stream. In the process industry, there are multiple waste heat streams, forming a complex heat source profile. In this paper, based on the simulation model developed in the Aspen Hysys software, the two cycles are calculated and compared. According to the waste heat composite curve, the multi-stream waste heat is divided into three kinds, straight, convex, and concave waste heat. Two parameters, the ratio of the heat above and below the most salient/concave point (R) and the temperature of the most point, are used to roughly express the feature of waste heat. With the efficiency from waste heat (exergy) to power as energy performance indicator, the calculation results for waste heat with maximum supply temperature 180 °C show that for straight and concave waste heat with R not less than 0.2, Kalina cycle is better than ORC, while for convex waste heat, ORC is preferable. The work can provide a reference to choose a suitable technology to recover low temperature waste heat for power generation in the process industry.

  8. THERMODYNAMIC ANALYSIS OF CARBON SEQUESTRATION METHODS IN LIGNITE POWER PLANTS

    International Nuclear Information System (INIS)

    Koroneos J. Christopher; Sakiltzis Christos; Rovas C. Dimitrios

    2008-01-01

    The green house effect is a very pressing issue of our times due to the big impact it will have in the future of life in our planet. The temperature increase of the earth which is the major impact of the greenhouse effect may change forever the climate and the way of life in many countries. It may lead to the reduction of agricultural production and at the end to famine, in several nations. The minimization of CO2 emissions and the introduction of new energy sources is the only solution to the catastrophe that is coming if inaction prevails. The objective of this work is to analyze the methods of the CO2 removal from the flue gases of power plants that use solid fuels. It is especially fit to the Greek conditions where the main fuel used is lignite. Three methods have been examined and compared thermodynamically. These are: (a) Removal of CO2 from the flue gas stream by absorption, (b) The combustion of lignite with pure oxygen and (c) The gasification of lignite. The lignite used in the analysis is the Greek lignite, produced at the Western Macedonia mines. The power plant, before carbon sequestration, has an efficiency of 39%, producing 330MW of electric power. After sequestration, the CO2 is compressed to pressures between 80-110 atm, before its final disposal. In the first method, the sequestration of CO2 is done utilizing a catalyst. The operation requires electricity and high thermal load which is received from low pressure steam extracted from the turbines. Additionally, electricity is required for the compression of the CO2 to 100 bars. This leads to a lower efficiency of the power plant by by 13%. In the second method, the lignite combustion is done with pure O2 produced at an air separation unit. The flue gasses are made up of CO2 and water vapor. This method requires electricity for carbon dioxide compression and the Air Separation unit, thus, the power plant efficiency is lowered by 26%. In the lignite gasification method, the products are a mixture of

  9. A combined thermodynamic cycle used for waste heat recovery of internal combustion engine

    International Nuclear Information System (INIS)

    He, Maogang; Zhang, Xinxin; Zeng, Ke; Gao, Ke

    2011-01-01

    In this paper, we present a steady-state experiment, energy balance and exergy analysis of exhaust gas in order to improve the recovery of the waste heat of an internal combustion engine (ICE). Considering the different characteristics of the waste heat of exhaust gas, cooling water, and lubricant, a combined thermodynamic cycle for waste heat recovery of ICE is proposed. This combined thermodynamic cycle consists of two cycles: the organic Rankine cycle (ORC), for recovering the waste heat of lubricant and high-temperature exhaust gas, and the Kalina cycle, for recovering the waste heat of low-temperature cooling water. Based on Peng–Robinson (PR) equation of state (EOS), the thermodynamic parameters in the high-temperature ORC were calculated and determined via an in-house computer program. Suitable working fluids used in high-temperature ORC are proposed and the performance of this combined thermodynamic cycle is analyzed. Compared with the traditional cycle configuration, more waste heat can be recovered by the combined cycle introduced in this paper. -- Highlights: ► We study the energy balance of fuel in internal combustion engine. ► Heat recovery effect of exhaust gas is good when ICE is at a high-load condition. ► We propose a new combined thermodynamic cycle for waste heat of ICE. ► The combined cycle has a higher recovery efficiency than previous configurations.

  10. 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.

  11. Optimum gas turbine cycle for combined cycle power plant

    International Nuclear Information System (INIS)

    Polyzakis, A.L.; Koroneos, C.; Xydis, G.

    2008-01-01

    The gas turbine based power plant is characterized by its relatively low capital cost compared with the steam power plant. It has environmental advantages and short construction lead time. However, conventional industrial engines have lower efficiencies, especially at part load. One of the technologies adopted nowadays for efficiency improvement is the 'combined cycle'. The combined cycle technology is now well established and offers superior efficiency to any of the competing gas turbine based systems that are likely to be available in the medium term for large scale power generation applications. This paper has as objective the optimization of a combined cycle power plant describing and comparing four different gas turbine cycles: simple cycle, intercooled cycle, reheated cycle and intercooled and reheated cycle. The proposed combined cycle plant would produce 300 MW of power (200 MW from the gas turbine and 100 MW from the steam turbine). The results showed that the reheated gas turbine is the most desirable overall, mainly because of its high turbine exhaust gas temperature and resulting high thermal efficiency of the bottoming steam cycle. The optimal gas turbine (GT) cycle will lead to a more efficient combined cycle power plant (CCPP), and this will result in great savings. The initial approach adopted is to investigate independently the four theoretically possible configurations of the gas plant. On the basis of combining these with a single pressure Rankine cycle, the optimum gas scheme is found. Once the gas turbine is selected, the next step is to investigate the impact of the steam cycle design and parameters on the overall performance of the plant, in order to choose the combined cycle offering the best fit with the objectives of the work as depicted above. Each alterative cycle was studied, aiming to find the best option from the standpoint of overall efficiency, installation and operational costs, maintainability and reliability for a combined power

  12. Combined cycle power plant with integrated low temperature heat (LOTHECO)

    International Nuclear Information System (INIS)

    Kakaras, E.; Doukelis, A.; Leithner, R.; Aronis, N.

    2004-01-01

    The major driver to enhance the efficiency of the simple gas turbine cycle has been the increase in process conditions through advancements in materials and cooling methods. Thermodynamic cycle developments or cycle integration are among the possible ways to further enhance performance. The current paper presents the possibilities and advantages from the LOTHECO natural gas-fired combined cycle concept. In the LOTHECO cycle, low-temperature waste heat or solar heat is used for the evaporation of injected water droplets in the compressed air entering the gas turbine's combustion chamber. Following a description of this innovative cycle, its advantages are demonstrated by comparison between different gas turbine power generation systems for small and large-scale applications, including thermodynamic and economic analysis. A commercial gas turbine (ALSTOM GT10C) has been selected and computed with the heat mass balance program ENBIPRO. The results from the energy analysis are presented and the features of each concept are discussed. In addition, the exergy analysis provides information on the irreversibilities of each process and suggested improvements. Finally, the economic analysis reveals that the combined cycle plant with a heavy-duty gas turbine is the most efficient and economic way to produce electricity at base load. However, on a smaller scale, innovative designs, such as the LOTHECO concept, are required to reach the same level of performance at feasible costs

  13. Computational tool for simulation of power and refrigeration cycles

    Science.gov (United States)

    Córdoba Tuta, E.; Reyes Orozco, M.

    2016-07-01

    Small improvement in thermal efficiency of power cycles brings huge cost savings in the production of electricity, for that reason have a tool for simulation of power cycles allows modeling the optimal changes for a best performance. There is also a big boom in research Organic Rankine Cycle (ORC), which aims to get electricity at low power through cogeneration, in which the working fluid is usually a refrigerant. A tool to design the elements of an ORC cycle and the selection of the working fluid would be helpful, because sources of heat from cogeneration are very different and in each case would be a custom design. In this work the development of a multiplatform software for the simulation of power cycles and refrigeration, which was implemented in the C ++ language and includes a graphical interface which was developed using multiplatform environment Qt and runs on operating systems Windows and Linux. The tool allows the design of custom power cycles, selection the type of fluid (thermodynamic properties are calculated through CoolProp library), calculate the plant efficiency, identify the fractions of flow in each branch and finally generates a report very educational in pdf format via the LaTeX tool.

  14. Thermo-economic performance of HTGR Brayton power cycles

    International Nuclear Information System (INIS)

    Linares, J. L.; Herranz, L. E.; Moratilla, B. Y.; Fernandez-Perez, A.

    2008-01-01

    High temperature reached in High and Very High Temperature Reactors (VHTRs) results in thermal efficiencies substantially higher than those of actual nuclear power plants. A number of studies mainly driven by achieving optimum thermal performance have explored several layout. However, economic assessments of cycle power configurations for innovative systems, although necessarily uncertain at this time, may bring valuable information in relative terms concerning power cycle optimization. This paper investigates the thermal and economic performance direct Brayton cycles. Based on the available parameters and settings of different designs of HTGR power plants (GTHTR-300 and PBMR) and using the first and second laws of thermodynamics, the effects of compressor inter-cooling and of the compressor-turbine arrangement (i.e., single vs. multiple axes) on thermal efficiency have been estimated. The economic analysis has been based on the El-Sayed methodology and on the indirect derivation of the reactor capital investment. The results of the study suggest that a 1-axis inter-cooled power cycle has a similar thermal performance to the 3-axes one (around 50%) and, what's more, it is substantially less taxed. A sensitivity study allowed assessing the potential impact of optimizing several variables on cycle performance. Further than that, the cycle components costs have been estimated and compared. (authors)

  15. Thermodynamic analysis and theoretical study of a continuous operation solar-powered adsorption refrigeration system

    International Nuclear Information System (INIS)

    Hassan, H.Z.; Mohamad, A.A.

    2013-01-01

    Due to the intermittent nature of the solar radiation, the day-long continuous production of cold is a challenge for solar-driven adsorption cooling systems. In the present study, a developed solar-powered adsorption cooling system is introduced. The proposed system is able to produce cold continuously along the 24-h of the day. The theoretical thermodynamic operating cycle of the system is based on adsorption at constant temperature. Both the cooling system operating procedure as well as the theoretical thermodynamic cycle are described and explained. Moreover, a steady state differential thermodynamic analysis is performed for all components and processes of the introduced system. The analysis is based on the energy conservation principle and the equilibrium dynamics of the adsorption and desorption processes. The Dubinin–Astakhov adsorption equilibrium equation is used in this analysis. Furthermore, the thermodynamic properties of the refrigerant are calculated from its equation of state. The case studied represents a water chiller which uses activated carbon–methanol as the working pair. The chiller is found to produce a daily mass of 2.63 kg cold water at 0 °C from water at 25 °C per kg of adsorbent. Moreover, the proposed system attains a cooling coefficient of performance of 0.66. - Highlights: • A new continuous operation solar-driven adsorption refrigeration system is introduced. • The theoretical thermodynamic cycle is presented and explained. • A complete thermodynamic analysis is performed for all components and processes of the system. • Activated carbon–methanol is used as the working pair in the case study

  16. 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

  17. GESIT: a thermodynamic program for single cycle gas turbine plants with and without intercoolers

    Energy Technology Data Exchange (ETDEWEB)

    Heil, J

    1973-08-01

    A computer program for the thermodynamic modeling of singlecycle gas turbine plants is described. A high-temperature reactor is assumed as a heat source in the program, but the HTR can be replaced with another heat source without difficulty. Starting from a set of independent data, the program calculates efficiencies and mass flows. It indicates all values for a heat and power balance and prints out the temperatures and pressures for the different parts of the cycle. Besides this, the program is able to optimize the compression ratios for minimal power input. It also takes into account turbine rotor cooling (at the roots of the blades). Furthermore, the program is able to use either total pressure loss or specified losses in different parts of the cycle. The program GESlT can also handle systems with one or two intercoolers, or with no intercooler. GESIT gives all input and output values for the heat exchangers and turbo-machines. First the single-cycle gas turbine plant is described. After that the computational basis for the program and the program structure is explained. Instructions for data input are given so that the program can be immediately utilized. An example of input data together with the associated output is presented. (auth)

  18. Thermally regenerative hydrogen/oxygen fuel cell power cycles

    Science.gov (United States)

    Morehouse, J. H.

    1986-01-01

    Two innovative thermodynamic power cycles are analytically examined for future engineering feasibility. The power cycles use a hydrogen-oxygen fuel cell for electrical energy production and use the thermal dissociation of water for regeneration of the hydrogen and oxygen. The TDS (thermal dissociation system) uses a thermal energy input at over 2000 K to thermally dissociate the water. The other cycle, the HTE (high temperature electrolyzer) system, dissociates the water using an electrolyzer operating at high temperature (1300 K) which receives its electrical energy from the fuel cell. The primary advantages of these cycles is that they are basically a no moving parts system, thus having the potential for long life and high reliability, and they have the potential for high thermal efficiency. Both cycles are shown to be classical heat engines with ideal efficiency close to Carnot cycle efficiency. The feasibility of constructing actual cycles is investigated by examining process irreversibilities and device efficiencies for the two types of cycles. The results show that while the processes and devices of the 2000 K TDS exceed current technology limits, the high temperature electrolyzer system appears to be a state-of-the-art technology development. The requirements for very high electrolyzer and fuel cell efficiencies are seen as determining the feasbility of the HTE system, and these high efficiency devices are currently being developed. It is concluded that a proof-of-concept HTE system experiment can and should be conducted.

  19. A comparative thermodynamic analysis of ORC and Kalina cycles for waste heat recovery: A case study for CGAM cogeneration system

    Directory of Open Access Journals (Sweden)

    Arash Nemati

    2017-03-01

    Full Text Available A thermodynamic modeling and optimization is carried out to compare the advantages and disadvantages of organic Rankine cycle (ORC and Kalina cycle (KC as a bottoming cycle for waste heat recovery from CGAM cogeneration system. Thermodynamic models for combined CGAM/ORC and CGAM/KC systems are performed and the effects of some decision variables on the energy and exergy efficiency and turbine size parameter of the combined systems are investigated. Solving simulation equations and optimization process have been done using direct search method by EES software. It is observed that at the optimum pressure ratio of air compressor, produced power of bottoming cycles has minimum values. Also, evaporator pressure optimizes the performance of cycle, but this optimum pressure level in ORC (11 bar is much lower than that of Kalina (46 bar. In addition, ORC's simpler configuration, higher net produced power and superheated turbine outlet flow, which leads to a reliable performance for turbine, are other advantages of ORC. Kalina turbine size parameter is lower than that of the ORC which is a positive aspect of Kalina cycle. However, by a comprehensive comparison between Kalina and ORC, it is concluded that the ORC has significant privileges for waste heat recovery in this case.

  20. Influence of different means of turbine blade cooling on the thermodynamic performance of combined cycle

    International Nuclear Information System (INIS)

    Sanjay; Singh, Onkar; Prasad, B.N.

    2008-01-01

    A comparative study of the influence of different means of turbine blade cooling on the thermodynamic performance of combined cycle power plant is presented. Seven schemes involving air and steam as coolants under open and closed loop cooling techniques have been studied. The open loop incorporates the internal convection, film and transpiration cooling techniques. Closed loop cooling includes only internal convection cooling. It has been found that closed loop steam cooling offers more specific work and consequently gives higher value of plant efficiency of about 60%, whereas open loop transpiration steam cooling, open loop steam internal convection cooling, transpiration air cooling, film steam cooling, film air, and internal convection air cooling have been found to yield lower values of plant efficiency in decreasing order as compared to closed loop steam cooling

  1. Thermodynamical cycle analysis of gas in a thermocompressor

    Energy Technology Data Exchange (ETDEWEB)

    Arques, P.

    1998-07-01

    A thermocompressor is a compressor that transforms the heat of a source into an energy of pressure without intermediate mechanical work. It is a Stirling engine simplification into a driven machine for which the piston that provides the power has been suppressed. This thermocompressor comprises a free piston displacer that separates cold and hot gas. The simulation takes into account the movement of the piston, heat transfers and variable mass with the time. The thermocompressor is a compressor of gas that works between one hot and one cold source. This compressor has neither crankshaft nor connecting rod assembly. In this paper, the author presents some results concerning this type of compressor. The ratio of pressures that it is possible to obtain is a function of the ratio of hot and cold source temperatures and of the extreme volume ratio. The global efficiency of the cycle with the regenerator go up by an maximum independent of the regenerator efficiency. The open cycle is executed in a thermocompressor that has a free piston separating cold and hot gas, intake and exhaust valves and the regenerator. The thermocompressor compression efficiency decreases when the volumetric ratio increases. For the gas, it is therefore desirable to have an extreme volume ratio closest to 1. In the paper, the author presents : Actual and calculated evolution of the free piston velocity compared to the theoretical evolution obtained by calculation with a pressure linearisation; friction influence between piston and cylinder; the differential equation of the movement of the piston; the period of pulsation of the piston; influence of the piston adiabaticity. By analytical study followed by an actual simulation, the author shows that: the regenerator efficiency has a very strong influence on the engine efficiency; taking into account the hot source temperature, the choice of volumes has affects the efficiency, consequences which must be taken into account.

  2. Thermodynamic, energy efficiency, and power density analysis of reverse electrodialysis power generation with natural salinity gradients

    NARCIS (Netherlands)

    Yip, N.Y.; Vermaas, D.A.; Nijmeijer, K.; Elimelech, M.

    2014-01-01

    Reverse electrodialysis (RED) can harness the Gibbs free energy of mixing when fresh river water flows into the sea for sustainable power generation. In this study, we carry out a thermodynamic and energy efficiency analysis of RED power generation, and assess the membrane power density. First, we

  3. Low-temperature behaviour of an ideal Bose gas and some forbidden thermodynamic cycles

    International Nuclear Information System (INIS)

    Chen Jincan; Lin Bihong

    2003-01-01

    Based on the equation of state of an ideal Bose gas, the heat capacities at constant volume and constant pressure of the Bose system are derived and used to analyse the low-temperature behaviour of the Bose system. It is expounded that some important thermodynamic processes such as a constant pressure and an adiabatic process cannot be carried out from the region of T > T c to that of T c , where T c is the critical temperature of Bose-Einstein condensation of the Bose system. Consequently, some typical thermodynamic cycles such as the Carnot cycle, Brayton cycle, Otto cycle, Ericsson cycle, Diesel cycle and Atkinson cycle cannot be operated across the critical temperature T c of Bose-Einstein condensation of an ideal Bose gas

  4. Dynamic simulation of combined cycle power plant cycling in the electricity market

    International Nuclear Information System (INIS)

    Benato, A.; Bracco, S.; Stoppato, A.; Mirandola, A.

    2016-01-01

    Highlights: • The flexibility of traditional power plants have become of primary importance. • Three dynamic models of the same single pressure HRSG are built. • The plant dynamic behaviour is predicted. • A lifetime calculation procedure is proposed and tested. • The drum lifetime reduction is estimated. - Abstract: The energy markets deregulation coupled with the rapid spread of unpredictable energy sources power units are stressing the necessity of improving traditional power plants flexibility. Cyclic operation guarantees high profits in the short term but, in the medium-long time, cause a lifetime reduction due to thermo-mechanical fatigue, creep and corrosion. In this context, Combined Cycle Power Plants are the most concerned in flexible operation problems. For this reason, two research groups from two Italian universities have developed a procedure to estimate the devices lifetime reduction with a particular focus on steam drums and superheaters/reheaters. To assess the lifetime reduction, it is essential to predict the thermodynamic variables trend in order to describe the plant behaviour. Therefore, the core of the procedure is the power plant dynamic model. At this purpose, in this paper, three different dynamic models of the same single pressure Combined Cycle Gas Turbine are presented. The models have been built using three different approaches and are used to simulate plant behaviour under real operating conditions. Despite these differences, the thermodynamic parameters time profiles are in good accordance as presented in the paper. At last, an evaluation of the drum lifetime reduction is performed.

  5. Preliminary thermodynamic study for an efficient turbo-blower external combustion Rankine cycle

    Science.gov (United States)

    Romero Gómez, Manuel; Romero Gómez, Javier; Ferreiro Garcia, Ramón; Baaliña Insua, Álvaro

    2014-08-01

    This research paper presents a preliminary thermodynamic study of an innovative power plant operating under a Rankine cycle fed by an external combustion system with turbo-blower (TB). The power plant comprises an external combustion system for natural gas, where the combustion gases yield their thermal energy, through a heat exchanger, to a carbon dioxide Rankine cycle operating under supercritical conditions and with quasi-critical condensation. The TB exploits the energy from the pressurised exhaust gases for compressing the combustion air. The study is focused on the comparison of the combustion system's conventional technology with that of the proposed. An energy analysis is carried out and the effect of the flue gas pressure on the efficiency and on the heat transfer in the heat exchanger is studied. The coupling of the TB results in an increase in efficiency and of the convection coefficient of the flue gas with pressure, favouring a reduced volume of the heat exchanger. The proposed innovative system achieves increases in efficiency of around 12 % as well as a decrease in the heat exchanger volume of 3/5 compared with the conventional technology without TB.

  6. Hybrid combined cycle power plant

    International Nuclear Information System (INIS)

    Veszely, K.

    2002-01-01

    In case of re-powering the existing pressurised water nuclear power plants by the proposed HCCPP solution, we can increase the electricity output and efficiency significantly. If we convert a traditional nuclear power plant unit to a HCCPP solution, we can achieve a 3.2-5.5 times increase in electricity output and the achievable gross efficiency falls between 46.8-52% and above, depending on the applied solution. These figures emphasise that we should rethink our power plant technologies and we have to explore a great variety of HCCPP solutions. This may give a new direction in the development of nuclear reactors and power plants as well.(author)

  7. Fast power cycle for fusion reactors

    International Nuclear Information System (INIS)

    Powell, J.; Fillo, J.; Makowitz, H.

    1978-01-01

    The unique, deep penetration capability of 14 MeV neutrons produced in DT fusion reactions allows the generation of very high temperature working fluid temperatures in a thermal power cycle. In the FAST (Fusion Augmented Steam Turbine) power cycle steam is directly superheated by the high temperature ceramic refractory interior of the blanket, after being generated by heat extracted from the relatively cool blanket structure. The steam is then passed to a high temperature gas turbine for power generation. Cycle studies have been carried out for a range of turbine inlet temperatures [1600 0 F to 3000 0 F (870 to 1650 0 C)], number of reheats, turbine mechanical efficiency, recuperator effectiveness, and system pressure losses. Gross cycle efficiency is projected to be in the range of 55 to 60%, (fusion energy to electric power), depending on parameters selected. Turbine inlet temperatures above 2000 0 F, while they do increase efficiency somewhat, are not necessarily for high cycle efficiency

  8. A review of chemical heat pumps, thermodynamic cycles and thermal energy storage technologies for low grade heat utilisation

    International Nuclear Information System (INIS)

    Chan, C.W.; Ling-Chin, J.; Roskilly, A.P.

    2013-01-01

    A major cause of energy inefficiency is a result of the generation of waste heat and the lack of suitable technologies for cost-effective utilisation of low grade heat in particular. The market potential for surplus/waste heat from industrial processes in the UK is between 10 TWh and 40 TWh, representing a significant potential resource which has remained unexploited to date. This paper reviews selected technologies suitable for utilisation of waste heat energy, with specific focus on low grade heat, including: (i) chemical heat pumps, such as adsorption and absorption cycles for cooling and heating; (ii) thermodynamic cycles, such as the organic Rankine cycle (ORC), the supercritical Rankine cycle (SRC) and the trilateral cycle (TLC), to produce electricity, with further focus on expander and zeotropic mixtures, and (iii) thermal energy storage, including sensible and latent thermal energy storages and their corresponding media to improve the performance of low grade heat energy systems. - Highlights: ► The review of various thermal technologies for the utilisation of under exploited low grade heat. ► The analyses of the absorption and adsorption heat pumps possibly with performance enhancement additives. ► The analyses of thermal energy storage technologies (latent and sensible) for heat storage. ► The analyses of low temperature thermodynamic cycles to maximise power production.

  9. Thermodynamic of the associated cycle and application to the assembly of thermochemical iodine sulphur cycle and a nuclear engine for the hydrogen production

    International Nuclear Information System (INIS)

    Dumont, Y.

    2008-01-01

    This thesis is devoted to the design of an assembly of a hydrogen production process by the thermochemical iodine-sulphur cycle and a nuclear reactor. The suggested coupling network uses a power cycle which produces a work which is directly used for the heat pump running. The purpose of this thermodynamic cycle association is to recover the rejected energy at low temperature of a process to provide the energy needs of this same process at high temperature. This association is applied to the studied coupling. The construction of the energy distribution network is designed by the pinch analysis. In the case of a conventional coupling, the efficiency of hydrogen production is 22.0%. By integrating the associated cycles into the coupling, the efficiency of production is 42.6%. The exergetic efficiency, representative of the energy using quality, increases from 58.7% to 85.4%. (author) [fr

  10. Thermodynamic Cycle and CFD Analyses for Hydrogen Fueled Air-breathing Pulse Detonation Engines

    Science.gov (United States)

    Povinelli, Louis A.; Yungster, Shaye

    2002-01-01

    This paper presents the results of a thermodynamic cycle analysis of a pulse detonation engine (PDE) using a hydrogen-air mixture at static conditions. The cycle performance results, namely the specific thrust, fuel consumption and impulse are compared to a single cycle CFD analysis for a detonation tube which considers finite rate chemistry. The differences in the impulse values were indicative of the additional performance potential attainable in a PDE.

  11. Thermodynamic performance analysis of a coupled transcritical and subcritical organic Rankine cycle system for waste heat recovery

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Xi Wu [Zhejiang Ocean University, Zhejian (China); Wang, Xiao Qiong; Li, You Rong; Wu, Chun Mei [Chongqing University, Chongqing (China)

    2015-07-15

    We present a novel coupled organic Rankine cycle (CORC) system driven by the low-grade waste heat, which couples a transcritical organic Rankine cycle with a subcritical organic Rankine cycle. Based on classical thermodynamic theory, a detailed performance analysis on the novel CORC system was performed. The results show that the pressure ratio of the expander is decreased in the CORC and the selection of the working fluids becomes more flexible and abundant. With the increase of the pinch point temperature difference of the internal heat exchanger, the net power output and thermal efficiency of the CORC all decrease. With the increase of the critical temperature of the working fluid, the system performance of the CORC is improved. The net power output and thermal efficiency of the CORC with isentropic working fluids are higher than those with dry working fluids.

  12. The universal power and efficiency characteristics for irreversible reciprocating heat engine cycles

    CERN Document Server

    Qin Xiao Yong; Sun Feng Rui; Wu Chih

    2003-01-01

    The performance of irreversible reciprocating heat engine cycles with heat transfer loss and friction-like term loss is analysed using finite-time thermodynamics. The universal relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, and the optimal relation between power output and the efficiency of the cycles are derived. Moreover, analysis and optimization of the model were carried out in order to investigate the effect of cycle processes on the performance of the cycle using numerical examples. The results obtained herein include the performance characteristics of irreversible reciprocating Diesel, Otto, Atkinson and Brayton cycles.

  13. Thermoeconomic analysis of a solar enhanced energy storage concept based on thermodynamic cycles

    International Nuclear Information System (INIS)

    Henchoz, Samuel; Buchter, Florian; Favrat, Daniel; Morandin, Matteo; Mercangöz, Mehmet

    2012-01-01

    Large scale energy storage may play an increasingly important role in the power generation and distribution sector, especially when large shares of renewable energies will have to be integrated into the electrical grid. Pumped-hydro is the only large scale storage technology that has been widely used. However the spread of this technology is limited by geographic constraints. In the present work, a particular implementation of a storage concept based on thermodynamic cycles, invented by ABB Switzerland ltd. Corporate Research, has been analysed thermoeconomically. A variant using solar thermal collectors is presented. It benefits from the synergy between daily variations in solar irradiance and in electricity demand. This results in an effective increase of the electric energy storage efficiency. A steady state multi-objective optimization of a 50 MW plant was done; minimizing the investment costs and maximizing the energy storage efficiency. Several types of cold storage substances have been implemented in the formulation and two different types of solar collector were investigated. A storage efficiency of 57% at a cost of 1200 USD/kW was calculated for an optimized plant using solar energy. Finally, a computation of the behaviour of the plant along the year showed a yearly availability of 84.4%. -- Highlights: ► A variant of electric energy storage based on thermodynamic cycles is presented. ► It uses solar collectors to improve the energy storage efficiency. ► An optimization minimizing capital cost and maximizing energy storage efficiency, was carried out. ► Capital costs lie between 982 and 3192 USD/kW and efficiency between 43.8% and 84.4%.

  14. Experimental opto-mechanics with levitated nanoparticles: towards quantum control and thermodynamic cycles (Presentation Recording)

    Science.gov (United States)

    Kiesel, Nikolai; Blaser, Florian; Delic, Uros; Grass, David; Dechant, Andreas; Lutz, Eric; Bathaee, Marzieh; Aspelmeyer, Markus

    2015-08-01

    Combining optical levitation and cavity optomechanics constitutes a promising approach to prepare and control the motional quantum state of massive objects (>10^9 amu). This, in turn, would represent a completely new type of light-matter interface and has, for example, been predicted to enable experimental tests of macrorealistic models or of non-Newtonian gravity at small length scales. Such ideas have triggered significant experimental efforts to realizing such novel systems. To this end, we have recently successfully demonstrated cavity-cooling of a levitated sub-micron silica particle in a classical regime at a pressure of approximately 1mbar. Access to higher vacuum of approx. 10^-6 mbar has been demonstrated using 3D-feedback cooling in optical tweezers without cavity-coupling. Here we will illustrate our strategy towards trapping, 3D-cooling and quantum control of nanoparticles in ultra-high vacuum using cavity-based feedback cooling methods and clean particle loading with hollow-core photonic crystal fibers. We will also discuss the current experimental progress both in 3D-cavity cooling and HCPCF-based transport of nanoparticles. As yet another application of cavity-controlled levitated nanoparticles we will show how to implement a thermodynamic Sterling cycle operating in the underdamped regime. We present optimized protocols with respect to efficiency at maximum power in this little explored regime. We also show that the excellent level of control in our system will allow reproducing all relevant features of such optimized protocols. In a next step, this will enable studies of thermodynamics cycles in a regime where the quantization of the mechanical motion becomes relevant.

  15. 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

  16. The realization and analysis of a new thermodynamic cycle for internal combustion engine

    Directory of Open Access Journals (Sweden)

    Dorić Jovan Ž.

    2011-01-01

    Full Text Available This paper presents description and thermodynamic analysis of a new thermodynamic cycle. Realization of this new cycle is possible to achieve with valveless internal combustion engine with more complete expansion. The main purpose of this new IC engine is to increase engines’ thermal efficiency. The engine was designed so that the thermodynamic changes of the working fluid are different than in conventional engines. Specific differences are reflected in a more complete expansion of the working fluid (the expansion stroke is larger than compression stroke, valveless gas flowing and complete discharge of residual combustion products from the combustion chamber. In this concept, the movement of the piston is different than in conventional piston mechanisms. The results obtained herein include the efficiency characteristics of irreversible reciprocating new engine cycle which is very similar to Miller cycle. The results show that with this thermodynamic cycle engine has higher efficiency than with the standard Otto cycle. In this article, the patent application material under number 2008/607 at the Intellectual Property Office of the Republic of Serbia was used.

  17. Thermoeconomic analysis and optimization of an ammonia–water power/cooling cogeneration cycle

    International Nuclear Information System (INIS)

    Zare, V.; Mahmoudi, S.M.S.; Yari, M.; Amidpour, M.

    2012-01-01

    The performance of an ammonia–water power/cooling cogeneration cycle is investigated and optimized paying more attention on the economic point of view. Thermodynamic and thermoeconomic models are developed in order to investigate the thermodynamic performance of the cycle and assess the unit cost of products. A parametric study is carried out and the cycle performance is optimized based on the thermal and exergy efficiencies as well as the sum of the unit costs of the system products. The results show that the sum of the unit cost of the cycle products obtained through thermoeconomic optimization is less than by around 18.6% and 25.9% compared to the cases when the cycle is optimized from the viewpoints of first and second laws of thermodynamics, respectively. It is also concluded that for each increase of $3/ton in unit cost of the steam as the heat source, the unit cost of the output power and cooling is increased by around $7.6/GJ and $15–19/GJ, respectively. -- Highlights: ► The theory of exergetic cost is applied to the case of ammonia–water power/cooling cycle. ► The cycle is optimized from the viewpoints of thermodynamics and economics. ► The economic optimization leads to a considerable reduction in the system product costs.

  18. Thermodynamic Analysis of Supplementary-Fired Gas Turbine Cycles

    DEFF Research Database (Denmark)

    Elmegaard, Brian; Henriksen, Ulrik Birk; Qvale, Einar Bjørn

    2002-01-01

    This paper presents an analysis of the possibilities for improving the efficiency of an indirectly biomass-fired gas turbine (IBFGT) by supplementary direct gas-firing. The supplementary firing may be based on natural gas, biogas, or pyrolysis gas. {The interest in this cycle arise from a recent...... demonstration of a two-stage gasification process through construction of several plants.} A preliminary analysis of the ideal recuperated Brayton cycle shows that for this cycle any supplementary firing will have a marginal efficiency of unity per extra unit of fuel. The same result is obtained...

  19. Thermodynamic Analysis of Supplementary-Fired Gas Turbine Cycles

    DEFF Research Database (Denmark)

    Elmegaard, Brian; Henriksen, Ulrik Birk; Qvale, Einar Bjørn

    2003-01-01

    to result in a high marginal efficiency. The paper shows that depending on the application, this is not always the case. The interest in this cycle arises from a recent demonstration of the feasibility of a two-stage gasification process through construction of several plants. The gas from this process...... could be divided into two streams, one for primary and one for supplementary firing. A preliminary analysis of the ideal, recuperated Brayton cycle shows that for this cycle any supplementary firing will have a marginal efficiency of unity per extra unit of fuel. The same result is obtained...

  20. Thermodynamic limit for coherence-limited solar power conversion

    Science.gov (United States)

    Mashaal, Heylal; Gordon, Jeffrey M.

    2014-09-01

    The spatial coherence of solar beam radiation is a key constraint in solar rectenna conversion. Here, we present a derivation of the thermodynamic limit for coherence-limited solar power conversion - an expansion of Landsberg's elegant basic bound, originally limited to incoherent converters at maximum flux concentration. First, we generalize Landsberg's work to arbitrary concentration and angular confinement. Then we derive how the values are further lowered for coherence-limited converters. The results do not depend on a particular conversion strategy. As such, they pertain to systems that span geometric to physical optics, as well as classical to quantum physics. Our findings indicate promising potential for solar rectenna conversion.

  1. Nuclear power and its fuel cycle

    International Nuclear Information System (INIS)

    Wymer, R.G.

    1986-01-01

    A series of viewgraphs describes the nuclear fuel cycle and nuclear power, covering reactor types, sources of uranium, enrichment of uranium, fuel fabrication, transportation, fuel reprocessing, and radioactive wastes

  2. Property Uncertainty Analysis and Methods for Optimal Working Fluids of Thermodynamic Cycles

    DEFF Research Database (Denmark)

    Frutiger, Jerome

    in the context of an industrial organic Rankine cycle, used for the recovery of waste heat from an engine of a marine container ship. The study illustrates that the model structure is vital for the uncertainties of equations of state and suggests that uncertainty becomes a criterion (along with e.g. goodness......-of-fit or ease of use) for the selection of an equation of state for a specific application. Furthermore, two studies on the identification of suitable working fluids for thermodynamic cycles are presented. The first one selects and assesses working fluid candidates for an organic Rankine cycle system to recover......There is an increasing interest in recovering industrial waste heat at low tempera-tures (70-250◦C). Thermodynamic cycles, such as heat pumps or organic Rankine cycles, can recover this heat and transfer it to other process streams or convert it into electricity. The working fluid, circulating...

  3. ThermoCycle: A Modelica library for the simulation of thermodynamic systems

    DEFF Research Database (Denmark)

    Quoilin, Sylvain; Desideri, Adriano; Wronski, Jorrit

    2014-01-01

    This paper presents the results of an on-going project to develop ThermoCycle, an open Modelica library for the simulation of low-capacity thermodynamic cycles and thermal systems. Special attention is paid to robustness and simulation speed since dynamic simulations are often limited by numerical...... constraints and failures, either during initialization or during integration. Furthermore, the use of complex equations of state (EOS) to compute thermodynamic properties significantly decreases the simulation speed. In this paper, the approach adopted in the library to overcome these challenges is presented...

  4. Brayton cycle space power systems

    International Nuclear Information System (INIS)

    Pietsch, A.; Trimble, S.W.; Harper, A.D.

    1985-01-01

    The latest accomplishments in the design and development of the Brayton Isotope Power System (BIPS) for space applications are described, together with a reexamination of the design/cost tradeoffs with respect to current economic parameters and technology status. The results of tests performed on a ground test version of the flight configuration, the workhorse loop, were used to confirm the performance projections made for the flight system. The results of cost-model analysis indicate that the use of the highest attainable power conversion system efficiency will yield the most cost-effective systems. 13 references

  5. Thermodynamic Optimization of a Geothermal- Based Organic Rankine Cycle System Using an Artificial Bee Colony Algorithm

    Directory of Open Access Journals (Sweden)

    Osman Özkaraca

    2017-10-01

    Full Text Available Geothermal energy is a renewable form of energy, however due to misuse, processing and management issues, it is necessary to use the resource more efficiently. To increase energy efficiency, energy systems engineers carry out careful energy control studies and offer alternative solutions. With this aim, this study was conducted to improve the performance of a real operating air-cooled organic Rankine cycle binary geothermal power plant (GPP and its components in the aspects of thermodynamic modeling, exergy analysis and optimization processes. In-depth information is obtained about the exergy (maximum work a system can make, exergy losses and destruction at the power plant and its components. Thus the performance of the power plant may be predicted with reasonable accuracy and better understanding is gained for the physical process to be used in improving the performance of the power plant. The results of the exergy analysis show that total exergy production rate and exergy efficiency of the GPP are 21 MW and 14.52%, respectively, after removing parasitic loads. The highest amount of exergy destruction occurs, respectively, in condenser 2, vaporizer HH2, condenser 1, pumps 1 and 2 as components requiring priority performance improvement. To maximize the system exergy efficiency, the artificial bee colony (ABC is applied to the model that simulates the actual GPP. Under all the optimization conditions, the maximum exergy efficiency for the GPP and its components is obtained. Two of these conditions such as Case 4 related to the turbine and Case 12 related to the condenser have the best performance. As a result, the ABC optimization method provides better quality information than exergy analysis. Based on the guidance of this study, the performance of power plants based on geothermal energy and other energy resources may be improved.

  6. Parametric analysis for a new combined power and ejector-absorption refrigeration cycle

    International Nuclear Information System (INIS)

    Wang Jiangfeng; Dai Yiping; Zhang Taiyong; Ma Shaolin

    2009-01-01

    A new combined power and ejector-absorption refrigeration cycle is proposed, which combines the Rankine cycle and the ejector-absorption refrigeration cycle, and could produce both power output and refrigeration output simultaneously. This combined cycle, which originates from the cycle proposed by authors previously, introduces an ejector between the rectifier and the condenser, and provides a performance improvement without greatly increasing the complexity of the system. A parametric analysis is conducted to evaluate the effects of the key thermodynamic parameters on the cycle performance. It is shown that heat source temperature, condenser temperature, evaporator temperature, turbine inlet pressure, turbine inlet temperature, and basic solution ammonia concentration have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. It is evident that the ejector can improve the performance of the combined cycle proposed by authors previously.

  7. Thermodynamic analysis of a new combined cooling and power system using ammonia–water mixture

    International Nuclear Information System (INIS)

    Wang, Jiangfeng; Wang, Jianyong; Zhao, Pan; Dai, Yiping

    2016-01-01

    Highlights: • A new combined cooling and power system is proposed. • Exergy destruction analysis is used to identify irreversibility of components in system. • Thermodynamic parameter analysis is performed for system. - Abstract: In order to achieve both power and cooling supply for users, a new combined cooling and power system using ammonia–water mixture is proposed to utilizing low grade heat sources, such as industrial waste heat, solar energy and geothermal energy. The proposed system combines a Kalina cycle and an ammonia–water absorption refrigeration cycle, in which the ammonia–water turbine exhaust is delivered to a separator to extract purer ammonia vapor. The purer ammonia vapor enters an evaporator to generate refrigeration output after being condensed and throttled. Mathematical models are established to simulate the combined system under steady-state conditions. Exergy destruction analysis is conducted to display the exergy destruction distribution in the system qualitatively and the results show that the major exergy destruction occurs in the heat exchangers. Finally a thermodynamic sensitivity analysis is performed and reveals that with an increase in the pressure of separator I or the ammonia mass fraction of basic solution, thermal efficiency and exergy efficiency of the system increase, whereas with an increase in the temperature of separator I, the ammonia–water turbine back pressure or the condenser II pressure, thermal efficiency and exergy efficiency of the system drop.

  8. Thermodynamic analysis of CO2 capture processes for power plants

    OpenAIRE

    Biyouki, Zeinab Amrollahi

    2014-01-01

    This thesis work presents an evaluation of various processes for reducing CO2 emissions from natural-gas-fired combined cycle (NGCC) power plants. The scope of the thesis is to focus mainly on post-combustion chemical absorption for NGCC. For the post-combustion capture plant, an important interface is the steam extraction from the steam turbine in order to supply the heat for solvent regeneration. The steam extraction imposes a power production penalty. The thesis includes analysis and compa...

  9. Parametric optimization design for supercritical CO2 power cycle using genetic algorithm and artificial neural network

    International Nuclear Information System (INIS)

    Wang Jiangfeng; Sun Zhixin; Dai Yiping; Ma Shaolin

    2010-01-01

    Supercritical CO 2 power cycle shows a high potential to recover low-grade waste heat due to its better temperature glide matching between heat source and working fluid in the heat recovery vapor generator (HRVG). Parametric analysis and exergy analysis are conducted to examine the effects of thermodynamic parameters on the cycle performance and exergy destruction in each component. The thermodynamic parameters of the supercritical CO 2 power cycle is optimized with exergy efficiency as an objective function by means of genetic algorithm (GA) under the given waste heat condition. An artificial neural network (ANN) with the multi-layer feed-forward network type and back-propagation training is used to achieve parametric optimization design rapidly. It is shown that the key thermodynamic parameters, such as turbine inlet pressure, turbine inlet temperature and environment temperature have significant effects on the performance of the supercritical CO 2 power cycle and exergy destruction in each component. It is also shown that the optimum thermodynamic parameters of supercritical CO 2 power cycle can be predicted with good accuracy using artificial neural network under variable waste heat conditions.

  10. Critical review of the first-law efficiency in different power combined cycle architectures

    International Nuclear Information System (INIS)

    Iglesias Garcia, Steven; Ferreiro Garcia, Ramon; Carbia Carril, Jose; Iglesias Garcia, Denis

    2017-01-01

    Highlights: • The adiabatic expansion based TC can improve the energy efficiency of CCs. • A revolutionary TC can be a starting point to develop high-performance CCs. • A theoretical thermal efficiency of 83.7% was reached in a Nuclear Power Plant using a TC as bottoming cycle. - Abstract: This critical review explores the potential of an innovative trilateral thermodynamic cycle used to transform low-grade heat into mechanical work and compares its performance with relevant traditional thermodynamic cycles in combined cycles. The aim of this work is to show that combined cycles use traditional low efficiency power cycles in their bottoming cycle, and to evaluate theoretically the implementation of alternative power bottoming cycles. Different types of combined cycles have been reviewed, highlighting their relevant characteristics. The efficiencies of power plants using combined cycles are reviewed and compared. The relevance of researching thermodynamic cycles for combined cycle applications is that a vast amount of heat energy is available at negligible cost in the bottoming cycle of a combined cycle, with the drawback that existing thermal cycles cannot make efficient use of such available low temperature heat due to their low efficiency. The first-law efficiency is used as a parameter to compare and suggest improvements in the combined cycles (CCs) reviewed. The analysis shows that trilateral cycles using closed processes are by far the most efficient published thermal cycles for combined cycles to transform low-grade heat into mechanical work. An innovative trilateral bottoming cycle is proposed to show that the application of non-traditional power cycles can increase significantly the first-law efficiency of CCs. The highest first-law efficiencies achieved are: 85.55% in a CC using LNG cool, 73.82% for a transport vehicle CC, 74.40% in a marine CC, 83.07% in a CC for nuclear power plants, 73.82% in a CC using Brayton and Rankine cycles, 78.31% in a CC

  11. Carbon Cycling with Nuclear Power

    Science.gov (United States)

    Lackner, Klaus S.

    2011-11-01

    Liquid hydrocarbon fuels like gasoline, diesel or jet fuel are the most efficient ways of delivering energy to the transportation sector, in particular cars, ships and airplanes. Unfortunately, their use nearly unavoidably leads to the emission of carbon dioxide into the atmosphere. Unless an equivalent amount is removed from the air, the carbon dioxide will accumulate and significantly contribute to the man-made greenhouse effect. If fuels are made from biomass, the capture of carbon dioxide is a natural part of the cycle. Here, we discuss technical options for capturing carbon dioxide at much faster rates. We outline the basic concepts, discuss how such capture technologies could be made affordable and show how they could be integrated into a larger system approach. In the short term, the likely source of the hydrocarbon fuels is oil or gas; in the longer term, technologies that can provide energy to remove oxygen from carbon dioxide and water molecules and combine the remaining components into liquid fuels make it possible to recycle carbon between fuels and carbon dioxide in an entirely abiotic process. Here we focus on renewable and nuclear energy options for producing liquid fuels and show how air capture combined with fuel synthesis could be more economic than a transition to electric cars or hydrogen-fueled cars.

  12. Performance analysis of Brayton cycle system for space power reactor

    International Nuclear Information System (INIS)

    Li Zhi; Yang Xiaoyong; Zhao Gang; Wang Jie; Zhang Zuoyi

    2017-01-01

    The closed Brayton cycle system now is the potential choice as the power conversion system for High Temperature Gas-cooled Reactors because of its high energy conversion efficiency and compact configuration. The helium is the best working fluid for the system for its chemical stability and small neutron absorption cross section. However, the Helium has small mole mass and big specific volume, which would lead to larger pipes and heat exchanger. What's more, the big compressor enthalpy rise of helium would also lead to an unacceptably large number of compressor's stage. For space use, it's more important to satisfy the limit of the system's volume and mass, instead of the requirement of the system's thermal capacity. So Noble-Gas binary mixture of helium and xenon is presented as the working fluid for space Brayton cycle. This paper makes a mathematical model for space Brayton cycle system by Fortran language, then analyzes the binary mixture of helium and xenon's properties and effects on power conversion units of the space power reactor, which would be helpful to understand and design the space power reactor. The results show that xenon would lead to a worse system's thermodynamic property, the cycle's efficiency and specific power decrease as xenon's mole fraction increasing. On the other hand, proper amount of xenon would decrease the enthalpy changes in turbomachines, which would be good for turbomachines' design. Another optimization method – the specific power optimization is also proposed to make a comparison. (author)

  13. Thermodynamic analyses of solar thermal gasification of coal for hybrid solar-fossil power and fuel production

    International Nuclear Information System (INIS)

    Ng, Yi Cheng; Lipiński, Wojciech

    2012-01-01

    Thermodynamic analyses are performed for solar thermal steam and dry gasification of coal. The selected types of coal are anthracite, bituminous, lignite and peat. Two model conversion paths are considered for each combination of the gasifying agent and the coal type: production of the synthesis gas with its subsequent use in a combined cycle power plant to generate power, and production of the synthesis gas with its subsequent use to produce gasoline via the Fischer–Tropsch synthesis. Replacement of a coal-fired 35% efficient Rankine cycle power plant and a combustion-based integrated gasification combined cycle power plant by a solar-based integrated gasification combined cycle power plant leads to the reduction in specific carbon dioxide emissions by at least 47% and 27%, respectively. Replacement of a conventional gasoline production process via coal gasification and a subsequent Fischer–Tropsch synthesis with gasoline production via solar thermal coal gasification with a subsequent Fischer–Tropsch synthesis leads to the reduction in specific carbon dioxide emissions by at least 39%. -- Highlights: ► Thermodynamic analyses for steam and dry gasification of coal are presented. ► Hybrid solar-fossil paths to power and fuels are compared to those using only combustion. ► Hybrid power production can reduce specific CO 2 emissions by more than 27%. ► Hybrid fuel production can reduce specific CO 2 emissions by more than 39%.

  14. Thermodynamic analysis of the heat regenerative cycle in porous medium engine

    International Nuclear Information System (INIS)

    Liu Hongsheng; Xie Maozhao; Wu Dan

    2009-01-01

    The advantages of homogeneous combustion in internal combustion engines are well known all over the world. Recent years, porous medium (PM) engine has been proposed as a new type engine based on the technique of combustion in porous medium, which can fulfils all requirements to perform homogeneous combustion. In this paper, working processes of a PM engine are briefly introduced and an ideal thermodynamic model of the PM heat regeneration cycle in PM engine is developed. An expression for the relation between net work output and thermal efficiency is derived for the cycle. In order to evaluate of the cycle, the influences of the expansion ratio, initial temperature and limited temperature on the net work and efficiency are discussed, and the availability terms of the cycle are analyzed. Comparing the PM heat regenerative cycle of the PM engine against Otto cycle and Diesel cycle shows that PM heat regenerative cycle can improve net work output greatly with little drop of efficiency. The aim of this paper is to predict the thermodynamic performance of PM heat regeneration cycle and provide a guide to further investigations of the PM engine

  15. A combined thermodynamic cycle based on methanol dissociation for IC (internal combustion) engine exhaust heat recovery

    International Nuclear Information System (INIS)

    Fu, Jianqin; Liu, Jingping; Xu, Zhengxin; Ren, Chengqin; Deng, Banglin

    2013-01-01

    In this paper, a novel approach for exhaust heat recovery was proposed to improve IC (internal combustion) engine fuel efficiency and also to achieve the goal for direct usage of methanol as IC engine fuel. An open organic Rankine cycle system using methanol as working medium is coupled to IC engine exhaust pipe for exhaust heat recovery. In the bottom cycle, the working medium first undergoes dissociation and expansion processes, and is then directed back to IC engine as fuel. As the external bottom cycle and the IC engine main cycle are combined together, this scheme forms a combined thermodynamic cycle. Then, this concept was applied to a turbocharged engine, and the corresponding simulation models were built for both of the external bottom cycle and the IC engine main cycle. On this basis, the energy saving potential of this combined cycle was estimated by parametric analyses. Compared to the methanol vapor engine, IC engine in-cylinder efficiency has an increase of 1.4–2.1 percentage points under full load conditions, while the external bottom cycle can increase the fuel efficiency by 3.9–5.2 percentage points at the working pressure of 30 bar. The maximum improvement to the IC engine global fuel efficiency reaches 6.8 percentage points. - Highlights: • A combined thermodynamic cycle using methanol as working medium for IC engine exhaust heat recovery is proposed. • The external bottom cycle of exhaust heat recovery and IC engine working cycle are combined together. • IC engine fuel efficiency could be improved from both in-cylinder working cycle and external bottom cycle. • The maximum improvement to the IC engine global fuel efficiency reaches 6.8 percentage points at full load

  16. Thermoeconomic optimization of a Kalina cycle for a central receiver concentrating solar power plant

    DEFF Research Database (Denmark)

    Modi, Anish; Kærn, Martin Ryhl; Andreasen, Jesper Graa

    2016-01-01

    with direct vapour generation and without storage. The use of the ammonia-water mixture as the power cycle working fluid with non-isothermal evaporation and condensation presents the potential to improve the overall performance of the plant. This however comes at a price of requiring larger heat exchangers...... because of lower thermal pinch and heat transfer degradation for mixtures as compared with using a pure fluid in a conventional steam Rankine cycle, and the necessity to use a complex cycle arrangement. Most of the previous studies on the Kalina cycle focused solely on the thermodynamic aspects......Concentrating solar power plants use a number of reflecting mirrors to focus and convert the incident solar energy to heat, and a power cycle to convert this heat into electricity. This paper evaluates the use of a high temperature Kalina cycle for a central receiver concentrating solar power plant...

  17. Thermodynamic and design considerations of organic Rankine cycles in combined application with a solar thermal gas turbine

    Science.gov (United States)

    Braun, R.; Kusterer, K.; Sugimoto, T.; Tanimura, K.; Bohn, D.

    2013-12-01

    Concentrated Solar Power (CSP) technologies are considered to provide a significant contribution for the electric power production in the future. Different kinds of technologies are presently in operation or under development, e.g. parabolic troughs, central receivers, solar dish systems and Fresnel reflectors. This paper takes the focus on central receiver technologies, where the solar radiation is concentrated by a field of heliostats in a receiver on the top of a tall tower. To get this CSP technology ready for the future, the system costs have to reduce significantly. The main cost driver in such kind of CSP technologies are the huge amount of heliostats. To reduce the amount of heliostats, and so the investment costs, the efficiency of the energy conversion cycle becomes an important issue. An increase in the cycle efficiency results in a decrease of the solar heliostat field and thus, in a significant cost reduction. The paper presents the results of a thermodynamic model of an Organic Rankine Cycle (ORC) for combined cycle application together with a solar thermal gas turbine. The gas turbine cycle is modeled with an additional intercooler and recuperator and is based on a typical industrial gas turbine in the 2 MW class. The gas turbine has a two stage radial compressor and a three stage axial turbine. The compressed air is preheated within a solar receiver to 950°C before entering the combustor. A hybrid operation of the gas turbine is considered. In order to achieve a further increase of the overall efficiency, the combined operation of the gas turbine and an Organic Rankine Cycle is considered. Therefore an ORC has been set up, which is thermally connected to the gas turbine cycle at two positions. The ORC can be coupled to the solar-thermal gas turbine cycle at the intercooler and after the recuperator. Thus, waste heat from different cycle positions can be transferred to the ORC for additional production of electricity. Within this investigation

  18. Detailed thermodynamic analysis of a diffusion-absorption refrigeration cycle

    International Nuclear Information System (INIS)

    Taieb, Ahmed; Mejbri, Khalifa; Bellagi, Ahmed

    2016-01-01

    This paper proposes an advanced simulation model for a Diffusion-Absorption Refrigerator DAR using ammonia/water/hydrogen as working fluids, and developed to describe and predict the behavior of the device under different operating conditions. The system is supposed to be cooled with ambient air and actuated with solar hot water available at 200 °C. The DAR is first simulated for a set of basic data; a COP of 0.126 associated to a cooling capacity of 22.3 W are found. Basing on the obtained results an exergetic analysis of the system is performed which shows that the rectifier contribution to the exergy destruction is the most important with 34%. In a second step, the thermal capacities of all heat exchangers of the DAR are evaluated and the mathematical model so modified that the calculated capacities are now used as input data. A parametric study of the cycle is then carried out. The COP is found to exhibit a maximum when the heat supplied to the boiler or to the bubble pump is varied. Similar behavior is observed for variable submergence ratio. It is further noted that the COP is very sensitive to the ambient air temperature and to the absorber efficiency. - Highlights: • A detailed model of a Diffusion Absorption is developed and simulated. • Irreversibility of each component of the cycle is examined. • A modified model based on thermal capacity of components of the DAR is elaborated. • System performance is calculated over a series of practical operating conditions.

  19. A multi-tank storage facility to effect power control in the PBMR power cycle

    International Nuclear Information System (INIS)

    Matimba, T.A.D.; Krueger, D.L.W.; Mathews, E.H.

    2007-01-01

    This article presents the concept of a storage facility used to effect power control in South Africa's PBMR power cycle. The concept features a multiple number of storage vessels whose purpose is to contain the working medium, helium, as it is withdrawn from the PBMR's closed loop power cycle, at low energy demand. This helium is appropriately replenished to the power cycle as the energy demand increases. Helium mass transfer between the power cycle and the storage facility, henceforth known as the inventory control system (ICS), is carried out by way of the pressure differential that exists between these two systems. In presenting the ICS concept, emphasis is placed on storage effectiveness; hence the discussion in this paper is centred on those features which accentuate storage effectiveness, namely:- Storage vessel multiplicity; - Unique initial pressures for each vessel arranged in a cascaded manner; and - A heat sink placed in each vessel to provide thermal inertia. Having presented the concept, the objective is to qualitatively justify the presence of each of the above-mentioned features using thermodynamics as a basis

  20. Dependence of cycle optimal configuration for closed gas turbines on thermodynamic properties of working fluids

    International Nuclear Information System (INIS)

    Andryushchenko, A.I.; Dubinin, A.B.; Krylov, E.E.

    1988-01-01

    The problem of choice of working fluids for NPP closed gas turbines (CGT) is discussed. Thermostable in the working temperature range, chemically inert relatively to structural materials, fire- and explosion - proof substances, radiation-resistant and having satisfactory neutron-physical characteristics are used as the working fluids. Final choice of a gas as a working fluid is exercised based on technical and economic comparison of different variants at optimum thermodynamic cycle and parameters for each gas. The character and degree of the effect of thermodynamic properties of gases on configuration of reference cycles of regenerative CGT are determined. It is established that efficiency and optimum parameters in nodal points of the reference cycle are specified by the degree of removing the compression processes from the critical point. Practical importance of the obtained results presupposes the possibility of rapid estimation of the efficiency of using a gas without multiparametric optimization

  1. Diagnostic system for combine cycle power plant

    International Nuclear Information System (INIS)

    Shimizu, Yujiro; Nomura, Masumi; Tanaka, Satoshi; Ito, Ryoji; Kita, Yoshiyuki

    2000-01-01

    We developed the Diagnostic System for Combined Cycle Power Plant which enables inexperienced operators as well as experienced operators to cope with abnormal conditions of Combined Cycle Power Plant. The features of this system are the Estimate of Emergency Level for Operation and the Prediction of Subsequent Abnormality, adding to the Diagnosis of Cause and the Operation Guidance. Moreover in this system, Diagnosis of Cause was improved by using our original method and support screens can be displayed for educational means in normal condition as well. (Authors)

  2. Multi-objective thermodynamic optimization of combined Brayton and inverse Brayton cycles using genetic algorithms

    International Nuclear Information System (INIS)

    Besarati, S.M.; Atashkari, K.; Jamali, A.; Hajiloo, A.; Nariman-zadeh, N.

    2010-01-01

    This paper presents a simultaneous optimization study of two outputs performance of a previously proposed combined Brayton and inverse Brayton cycles. It has been carried out by varying the upper cycle pressure ratio, the expansion pressure of the bottom cycle and using variable, above atmospheric, bottom cycle inlet pressure. Multi-objective genetic algorithms are used for Pareto approach optimization of the cycle outputs. The two important conflicting thermodynamic objectives that have been considered in this work are net specific work (w s ) and thermal efficiency (η th ). It is shown that some interesting features among optimal objective functions and decision variables involved in the Baryton and inverse Brayton cycles can be discovered consequently.

  3. Thermodynamic analysis of a new dual evaporator CO2 transcritical refrigeration cycle

    Science.gov (United States)

    Abdellaoui, Ezzaalouni Yathreb; Kairouani, Lakdar Kairouani

    2017-03-01

    In this work, a new dual-evaporator CO2 transcritical refrigeration cycle with two ejectors is proposed. In this new system, we proposed to recover the lost energy of condensation coming off the gas cooler and operate the refrigeration cycle ejector free and enhance the system performance and obtain dual-temperature refrigeration simultaneously. The effects of some key parameters on the thermodynamic performance of the modified cycle are theoretically investigated based on energetic and exergetic analysis. The simulation results for the modified cycle indicate more effective system performance improvement than the single ejector in the CO2 vapor compression cycle using ejector as an expander ranging up to 46%. The exergetic analysis for this system is made. The performance characteristics of the proposed cycle show its promise in dual-evaporator refrigeration system.

  4. Thermodynamic analysis of a new dual evaporator CO2 transcritical refrigeration cycle

    Directory of Open Access Journals (Sweden)

    Abdellaoui Ezzaalouni Yathreb

    2017-03-01

    Full Text Available In this work, a new dual-evaporator CO2 transcritical refrigeration cycle with two ejectors is proposed. In this new system, we proposed to recover the lost energy of condensation coming off the gas cooler and operate the refrigeration cycle ejector free and enhance the system performance and obtain dual-temperature refrigeration simultaneously. The effects of some key parameters on the thermodynamic performance of the modified cycle are theoretically investigated based on energetic and exergetic analysis. The simulation results for the modified cycle indicate more effective system performance improvement than the single ejector in the CO2 vapor compression cycle using ejector as an expander ranging up to 46%. The exergetic analysis for this system is made. The performance characteristics of the proposed cycle show its promise in dual-evaporator refrigeration system.

  5. Thermodynamic sensitivity analysis of a novel trigeneration thermodynamic cycle with two-phase expanders and two-phase compressors

    International Nuclear Information System (INIS)

    Briola, Stefano; Di Marco, Paolo; Gabbrielli, Roberto

    2017-01-01

    A novel Combined Cooling, Heating and Power (CCHP) cycle, operating with two-phase devices for the compression and expansion processes and a single-component wet working fluid, is proposed. A detailed sensitivity analysis of the novel CCHP cycle has been investigated in order to evaluate, in terms of energy performance indicators, its potentiality to serve typical trigenerative tertiary and industrial end-users with different fixed operating temperatures. In general, the novel CCHP cycle is characterized by higher energy performance indicators than a separated energy production system. The comparison between the novel CCHP cycle and several commercialized CCHP systems has been performed in the case studies related to tertiary and industrial end-users. The novel CCHP cycle shows a trigenerative capability in wide ranges of the end-users demands without surplus or deficit of the electric or thermal powers. Furthermore, the maximum allowable capital cost of the whole novel CCHP plant (BEPCC), that will assure the profitability of the investment, is calculated in the tertiary and industrial end-users case studies. For the tertiary end-user, the capital costs of the commercialized CCHP are between the minimum and maximum BEPCC values. On the contrary, for the industrial end-user, they are lower than the minimum and maximum BEPCC values. - Highlights: • Novel CCHP cycle with two-phase expanders and compressors has been conceived. • Novel CCHP cycle has higher performances than a separated energy production system. • Novel CCHP cycle satisfies the user demands in wide ranges without surplus/deficit. • Tertiary user: novel CCHP cycle is competitive against marketed CCHP systems. • Industrial user: novel CCHP cycle is not competitive against marketed CCHP systems.

  6. Closed-cycle cooling systems for nuclear power plants

    International Nuclear Information System (INIS)

    Santini, Lorenzo

    2006-01-01

    The long experience in the field of closed-cycle cooling systems and high technological level of turbo machines and heat exchangers concurs to believe in the industrial realizability of nuclear systems of high thermodynamic efficiency and intrinsic safety [it

  7. Mathematical modeling of the complete thermodynamic cycle of a new Atkinson cycle gas engine

    International Nuclear Information System (INIS)

    Shojaeefard, Mohammad Hassan; Keshavarz, Mojtaba

    2015-01-01

    The Atkinson cycle provides the potential to increase the efficiency of SI engines using overexpansion concept. This also will suggest decrease in CO_2 generation by internal combustion engine. In this study a mathematical modeling of complete thermodynamic cycle of a new two-stroke Atkinson cycle SI engine will be presented. The mathematical modeling is carried out using two-zone combustion analysis in order to make the model predict exhaust emission so that its values could be compared with the values of conventional SI engine. The model also is validated against experimental tests in that increase in efficiency is achieved compared to conventional SI engines. - Highlights: • The complete cycle model for the rotary Atkinson engine was developed. • Comparing the results with experimental data shows good model validity. • The model needs further improvement for the scavenging phase. • There is 5% increment in thermal efficiency with new engine compared to conventional SI engines.

  8. Minimization of the LCA impact of thermodynamic cycles using a combined simulation-optimization approach

    International Nuclear Information System (INIS)

    Brunet, Robert; Cortés, Daniel; Guillén-Gosálbez, Gonzalo; Jiménez, Laureano; Boer, Dieter

    2012-01-01

    This work presents a computational approach for the simultaneous minimization of the total cost and environmental impact of thermodynamic cycles. Our method combines process simulation, multi-objective optimization and life cycle assessment (LCA) within a unified framework that identifies in a systematic manner optimal design and operating conditions according to several economic and LCA impacts. Our approach takes advantages of the complementary strengths of process simulation (in which mass, energy balances and thermodynamic calculations are implemented in an easy manner) and rigorous deterministic optimization tools. We demonstrate the capabilities of this strategy by means of two case studies in which we address the design of a 10 MW Rankine cycle modeled in Aspen Hysys, and a 90 kW ammonia-water absorption cooling cycle implemented in Aspen Plus. Numerical results show that it is possible to achieve environmental and cost savings using our rigorous approach. - Highlights: ► Novel framework for the optimal design of thermdoynamic cycles. ► Combined use of simulation and optimization tools. ► Optimal design and operating conditions according to several economic and LCA impacts. ► Design of a 10MW Rankine cycle in Aspen Hysys, and a 90kW absorption cycle in Aspen Plus.

  9. Minimization of the LCA impact of thermodynamic cycles using a combined simulation-optimization approach

    Energy Technology Data Exchange (ETDEWEB)

    Brunet, Robert; Cortes, Daniel [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Campus Sescelades, Avinguda Paisos Catalans 26, 43007 Tarragona (Spain); Guillen-Gosalbez, Gonzalo [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Campus Sescelades, Avinguda Paisos Catalans 26, 43007 Tarragona (Spain); Jimenez, Laureano [Departament d' Enginyeria Quimica, Escola Tecnica Superior d' Enginyeria Quimica, Universitat Rovira i Virgili, Campus Sescelades, Avinguda Paisos Catalans 26, 43007 Tarragona (Spain); Boer, Dieter [Departament d' Enginyeria Mecanica, Escola Tecnica Superior d' Enginyeria, Universitat Rovira i Virgili, Campus Sescelades, Avinguda Paisos Catalans 26, 43007, Tarragona (Spain)

    2012-12-15

    This work presents a computational approach for the simultaneous minimization of the total cost and environmental impact of thermodynamic cycles. Our method combines process simulation, multi-objective optimization and life cycle assessment (LCA) within a unified framework that identifies in a systematic manner optimal design and operating conditions according to several economic and LCA impacts. Our approach takes advantages of the complementary strengths of process simulation (in which mass, energy balances and thermodynamic calculations are implemented in an easy manner) and rigorous deterministic optimization tools. We demonstrate the capabilities of this strategy by means of two case studies in which we address the design of a 10 MW Rankine cycle modeled in Aspen Hysys, and a 90 kW ammonia-water absorption cooling cycle implemented in Aspen Plus. Numerical results show that it is possible to achieve environmental and cost savings using our rigorous approach. - Highlights: Black-Right-Pointing-Pointer Novel framework for the optimal design of thermdoynamic cycles. Black-Right-Pointing-Pointer Combined use of simulation and optimization tools. Black-Right-Pointing-Pointer Optimal design and operating conditions according to several economic and LCA impacts. Black-Right-Pointing-Pointer Design of a 10MW Rankine cycle in Aspen Hysys, and a 90kW absorption cycle in Aspen Plus.

  10. Nuclear power and the nuclear fuel cycle

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1976-07-01

    The IAEA is organizing a major conference on nuclear power and the nuclear fuel cycle, which is to be held from 2 to 13 May 1977 in Salzburg, Austria. The programme for the conference was published in the preceding issue of the IAEA Bulletin (Vol.18, No. 3/4). Topics to be covered at the conference include: world energy supply and demand, supply of nuclear fuel and fuel cycle services, radioactivity management (including transport), nuclear safety, public acceptance of nuclear power, safeguarding of nuclear materials, and nuclear power prospects in developing countries. The articles in the section that follows are intended to serve as an introduction to the topics to be discussed at the Salzburg Conference. They deal with the demand for uranium and nuclear fuel cycle services, uranium supplies, a computer simulation of regional fuel cycle centres, nuclear safety codes, management of radioactive wastes, and a pioneering research project on factors that determine public attitudes toward nuclear power. It is planned to present additional background articles, including a review of the world nuclear fuel reprocessing situation and developments in the uranium enrichment industry, in future issues of the Bulletin. (author)

  11. Nuclear power and the nuclear fuel cycle

    International Nuclear Information System (INIS)

    Hardy, C.J.; Silver, J.M.

    1985-09-01

    The report provides data and assessments of the status and prospects of nuclear power and the nuclear fuel cycle. The report discusses the economic competitiveness of nuclear electricity generation, the extent of world uranium resources, production and requirements, uranium conversion and enrichment, fuel fabrication, spent fuel treatment and radioactive waste management. A review is given of the status of nuclear fusion research

  12. Parametric analysis and optimization for a combined power and refrigeration cycle

    International Nuclear Information System (INIS)

    Wang Jiangfeng; Dai Yiping; Gao Lin

    2008-01-01

    A combined power and refrigeration cycle is proposed, which combines the Rankine cycle and the absorption refrigeration cycle. This combined cycle uses a binary ammonia-water mixture as the working fluid and produces both power output and refrigeration output simultaneously with only one heat source. A parametric analysis is conducted to evaluate the effects of thermodynamic parameters on the performance of the combined cycle. It is shown that heat source temperature, environment temperature, refrigeration temperature, turbine inlet pressure, turbine inlet temperature, and basic solution ammonia concentration have significant effects on the net power output, refrigeration output and exergy efficiency of the combined cycle. A parameter optimization is achieved by means of genetic algorithm to reach the maximum exergy efficiency. The optimized exergy efficiency is 43.06% under the given condition

  13. Study on thermodynamic cycle of high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Qu Xinhe; Yang Xiaoyong; Wang Jie

    2017-01-01

    The development trend of the (very) High temperature gas-cooled reactor is to gradually increase the reactor outlet temperature. The different power conversion units are required at the different reactor outlet temperature. In this paper, for the helium turbine direct cycle and the combined cycle of the power conversion unit of the High temperature gas-cooled reactor, the mathematic models are established, and three cycle plans are designed. The helium turbine direct cycle is a Brayton cycle with recuperator, precooler and intercooler. In the combined cycle plan 1, the topping cycle is a simple Brayton cycle without recuperator, precooler and intercooler, and the bottoming cycle is based on the steam parameters (540deg, 6 MPa) recommended by Siemens. In the combined cycle plan 2, the topping cycle also is a simple Brayton cycle, and the bottoming cycle which is a Rankine cycle with reheating cycle is based on the steam parameters of conventional subcritical thermal power generation (540degC, 18 MPa). The optimization results showed that the cycle efficiency of the combined cycle plan 2 is the highest, the second is the helium turbine direct cycle, and the combined cycle plan 2 is the lowest. When the reactor outlet temperature is 900degC and the pressure ratio is 2.02, the cycle efficiency of the combined cycle plan 2 can reach 49.7%. The helium turbine direct cycle has a reactor inlet temperature above 500degC due to the regenerating cycle, so it requires a cooling circuit for the internal wall of the reactor pressure vessel. When the reactor outlet temperature increases, the increase of the pressure ratio required by the helium turbine direct cycle increases may bring some difficulties to the design and manufacture of the magnetic bearings. For the combined cycle, the reactor inlet temperature can be controlled below than 370degC, so the reactor pressure vessel can use SA533 steel without cooling the internal wall of the reactor pressure vessel. The pressure

  14. Modern concepts of thermodynamic optimization in Mexican thermoelectric power stations; Conceptos modernos de optimacion termodinamica en centrales termoelectricas mexicanas

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes de Gortari, J.; Vidal Santo, A.; Mendez Lavielle, F.; Bautista Godinez, O. [Facultad de Ingenieria, UNAM, Mexico, D.F. (Mexico)

    2002-03-01

    In this paper, a summary review of the current thermodynamic concepts to the maximum power generation and minimum entropy production are presented. The results of the analysis are considered in Mexican power stations using conventional cycles and are compared with other power stations around the world. [Spanish] En este trabajo se revisa el analisis de maxima generacion de potencia que implica la minimizacion de la produccion de entropia en centrales generadoras de potencia, de acuerdo con los lineamientos mas recientes publicados en la literatura. Los conceptos y resultados del analisis se aplican a varias centrales mexicanas y se comparan con otras centrales en el mundo.

  15. Enhancing power cycle efficiency for a supercritical Brayton cycle power system using tunable supercritical gas mixtures

    Science.gov (United States)

    Wright, Steven A.; Pickard, Paul S.; Vernon, Milton E.; Radel, Ross F.

    2017-08-29

    Various technologies pertaining to tuning composition of a fluid mixture in a supercritical Brayton cycle power generation system are described herein. Compounds, such as Alkanes, are selectively added or removed from an operating fluid of the supercritical Brayton cycle power generation system to cause the critical temperature of the fluid to move up or down, depending upon environmental conditions. As efficiency of the supercritical Brayton cycle power generation system is substantially optimized when heat is rejected near the critical temperature of the fluid, dynamically modifying the critical temperature of the fluid based upon sensed environmental conditions improves efficiency of such a system.

  16. Analysis of a novel solar energy-powered Rankine cycle for combined power and heat generation using supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.R.; Yamaguchi, H.; Uneno, D. [Department of Mechanical Engineering, Doshisha University, Kyoto 630-0321 (Japan); Fujima, K. [Mayekawa MFG Co., Ltd., 2000 Tatsuzawa Moriya-city, Ibaraki-Pref. 302-0118 (Japan); Enomoto, M. [Showa Denko K. K., 1-480, Inuzuka, Oyama-city, Tochigi 323-8679 (Japan); Sawada, N. [Showa Tansan Co., Ltd., 7-1, Ogimachi, Kawasaki-Ku, Kawasaki-city, Kanagawa 210-0867 (Japan)

    2006-10-15

    Theoretical analysis of a solar energy-powered Rankine thermodynamic cycle utilizing an innovative new concept, which uses supercritical carbon dioxide as a working fluid, is presented. In this system, a truly 'natural' working fluid, carbon dioxide, is utilized to generate firstly electricity power and secondly high-grade heat power and low-grade heat power. The uniqueness of the system is in the way in which both solar energy and carbon dioxide, available in abundant quantities in all parts of the world, are simultaneously used to build up a thermodynamic cycle and has the potential to reduce energy shortage and greatly reduce carbon dioxide emissions and global warming, offering environmental and personal safety simultaneously. The system consists of an evacuated solar collector system, a power-generating turbine, a high-grade heat recovery system, a low-grade heat recovery system and a feed pump. The performances of this CO{sub 2}-based Rankine cycle were theoretically investigated and the effects of various design conditions, namely, solar radiation, solar collector area and CO{sub 2} flow rate, were studied. Numerical simulations show that the proposed system may have electricity power efficiency and heat power efficiency as high as 11.4% and 36.2%, respectively. It is also found that the cycle performances strongly depend on climate conditions. Also the electricity power and heat power outputs increase with the collector area and CO{sub 2} flow rate. The estimated COP{sub power} and COP{sub heat} increase with the CO{sub 2} flow rate, but decrease with the collector area. The CO{sub 2}-based cycle can be optimized to provide maximum power, maximum heat recovery or a combination of both. The results suggest the potential of this new concept for applications to electricity power and heat power generation. (author)

  17. Maximisation of Combined Cycle Power Plant Efficiency

    Directory of Open Access Journals (Sweden)

    Janusz Kotowicz

    2015-12-01

    Full Text Available The paper presents concepts for increasing the efficiency of a modern combined cycle power plant. Improvement of gas turbine performance indicators as well as recovering heat from the air cooling the gas turbine’s flow system enable reaching gross electrical efficiencies of around 65%. Analyses for a wide range of compressor pressure ratios were performed. Operating characteristics were developed for the analysed combined cycle plant, for different types of open air cooling arrangements of the gas turbine’s expander: convective, transpiration and film.

  18. Utilization of waste heat from GT-MHR for power generation in organic Rankine cycles

    International Nuclear Information System (INIS)

    Yari, Mortaza; Mahmoudi, S.M.S.

    2010-01-01

    The gas turbine-modular helium reactor (GT-MHR) is currently being developed by an international consortium. In this power plant, circulating helium that has to be compressed in a single or two successive stages cools the reactor core. For thermodynamic reasons, these compression stages require pre-cooling of the helium to about 26 deg. C through the use of intercooler and pre-cooler in which water is used to cool the helium. Considerable thermal energy (∼300 MWth) is thus dissipated in these components. This thermal energy is then rejected to a heat sink. For different designs, the temperature ranges of the helium in the intercooler and pre-cooler could be about 100 and 150 deg. C, respectively. These are ideal energy sources to be used in an organic Rankine cycles for power generation. This study examines the performance of a gas-cooled nuclear power plant with closed Brayton cycle (CBC) combined with two organic Rankine cycles (ORC). More attention was paid to the irreversibilities generated in the combined cycle. Individual models are developed for each component through applications of the first and second laws of thermodynamics. The effects of the turbine inlet temperature, compressor pressure ratio, evaporator temperature and temperature difference in the evaporator on the first- and second-law efficiencies and on the exergy destruction rate of the combined cycle were studied. Finally the combined cycle was optimized thermodynamically using the EES (Engineering Equation Solver) software. Based on identical operating conditions, a comparison between the GT-MHR/ORC and a simple GT-MHR cycle is also made. It was found that both the first- and second-law efficiencies of GT-MHR/ORC cycle are about 3%-points higher than that of the simple GT-MHR cycle. Also, the exergy destruction rate for GT-MHR/ORC cycle is about 5% lower than that of the GT-MHR cycle.

  19. Combined production of hydrogen and power from heavy oil gasification: Pinch analysis, thermodynamic and economic evaluations

    Energy Technology Data Exchange (ETDEWEB)

    Domenichini, R.; Gallio, M. [Foster Wheeler Italiana Spa, via Caboto 1, 20094 Corsico (Milano) (Italy); Lazzaretto, A. [University of Padova, Department of Mechanical Engineering, via Venezia 1, 35131 Padova (Italy)

    2010-05-15

    Integrated Gasification Combined Cycle (IGCC) represents a commercially proven technology available for the combined production of hydrogen and electricity power from coal and heavy residue oils. When associated with CO{sub 2} capture and sequestration facilities, the IGCC plant gives an answer to the search for a clean and environmentally compatible use of high sulphur and heavy metal contents fuels, the possibility of installing large size plants for competitive electric power and hydrogen production, and a low cost of CO{sub 2} avoidance. The paper describes two new and realistic configurations of IGCC plant fed by refinery heavy residues and including a CO{sub 2} capture section, which are proposed on the basis of the experience gained in the construction of similar plants. They are based on oxygen blown entrained bed gasification and sized to produce a large amount of hydrogen and to feed one or two gas turbines of the combined cycle unit. The main thermodynamic and technological characteristics of the total plants are evaluated focusing on the heat integration between syngas cooling and combined cycle sections. Moreover, the overall performance characteristics and investment cost are estimated to supply a reliable estimate for the cost of electricity, given a value for the hydrogen selling price. (author)

  20. Combined production of hydrogen and power from heavy oil gasification: Pinch analysis, thermodynamic and economic evaluations

    International Nuclear Information System (INIS)

    Domenichini, R.; Gallio, M.; Lazzaretto, A.

    2010-01-01

    Integrated Gasification Combined Cycle (IGCC) represents a commercially proven technology available for the combined production of hydrogen and electricity power from coal and heavy residue oils. When associated with CO 2 capture and sequestration facilities, the IGCC plant gives an answer to the search for a clean and environmentally compatible use of high sulphur and heavy metal contents fuels, the possibility of installing large size plants for competitive electric power and hydrogen production, and a low cost of CO 2 avoidance. The paper describes two new and realistic configurations of IGCC plant fed by refinery heavy residues and including a CO 2 capture section, which are proposed on the basis of the experience gained in the construction of similar plants. They are based on oxygen blown entrained bed gasification and sized to produce a large amount of hydrogen and to feed one or two gas turbines of the combined cycle unit. The main thermodynamic and technological characteristics of the total plants are evaluated focusing on the heat integration between syngas cooling and combined cycle sections. Moreover, the overall performance characteristics and investment cost are estimated to supply a reliable estimate for the cost of electricity, given a value for the hydrogen selling price.

  1. Thermodynamic analysis of an Organic Rankine Cycle (ORC) based on industrial data

    International Nuclear Information System (INIS)

    Tumen Ozdil, N. Filiz; Segmen, M. Rıdvan; Tantekin, Atakan

    2015-01-01

    In this study, thermodynamic analysis of an Organic Rankine Cycle (ORC) is presented in a local power plant that is located southern of Turkey. The system that is analyzed includes an evaporator, a turbine, a condenser, a pump and a generator as components. System components are analyzed separately using actual plant data and performance cycle. The relationship between pinch point and exergy efficiency is observed. As the pinch point temperature decreases, the exergy efficiency increases due to low exergy destruction rate. The energy and exergy efficiencies of the ORC are calculated as 9.96% and 47.22%, respectively for saturated liquid form which is the real condition. In order to show the effect of the water phase of the evaporator inlet, exergy destruction and exergy efficiencies of components and overall system are calculated for different water phases. The exergy efficiency of the ORC is calculated as 41.04% for water mixture form which has quality 0.3. On the other hand, it is found as 40.29% for water mixture form which has quality 0.7. Lastly, it is calculated as 39.95% for saturated vapor form. Moreover, exergy destruction rates of the system are 520.01 kW for saturated liquid form, 598.39 kW for water mixture form which has quality 0.3, 609.5 kW for water mixture form which has quality 0.7 and 614.63 kW for saturated vapor form. The analyses show that evaporator has important effect on the system efficiency in terms of exergy rate. The evaporator is investigated particularly in order to improve the performance of the overall system. - Highlights: • Energy and exergy analysis of an Organic Rankine Cycle (ORC). • The main reasons of the irreversibility in the ORC. • Determination of exergy efficiency for the different water phases in the evaporator inlet. • Determination of the effect of the ambient temperature on ORC efficiency.

  2. Thermodynamics

    International Nuclear Information System (INIS)

    Zanchini, E.

    1988-01-01

    The definition of energy, in thermodynamics, is dependent by starting operative definitions of the basic concepts of physics on which it rests, such as those of isolated systems, ambient of a system, separable system and set of separable states. Then the definition of energy is rigorously extended to open systems. The extension gives a clear physical meaning to the concept of energy difference between two states with arbitrary different compositions

  3. Thermodynamic analysis of cooling systems for nuclear power stations condenser

    International Nuclear Information System (INIS)

    Beck, A.

    1985-06-01

    This work is an attempt to concentrate on the thermodynamic theory, the engineering solution and the quantities of water needed for the operation of a wet as well as a wet/dry cooling towers coupled to a nuclear turbine condenser,. About two hundred variables are needed for the design of a condenser - cooling tower system. In order to make the solution fast and handy, a computer model was developed. The amount of water evaporation from cooling towers is a function of the climate conditions prevailing around the site. To achieve an authentic analysis, the meteorological data of the northern Negev was used. The total amount of water necessary to add to the system in a year time of operation is large and is a function of both the blow-down rate and the evaporation. First estimations show that the use of a combined system, wet/dry cooling tower, is beneficial in the northern Negev area. Such a system can reduce significantly the amount of wasted fresh water. Lack of international experience is the major problem in the acceptability of wet/dry cooling towers. The technology of a wet cooling tower using sea water is also discussed where no technical or engineering limitations were found. This work is an attempt to give some handy tools for making the choice of cooling systems for nuclear power plants easier

  4. Hydrogen Monitoring in Nuclear Power Cycles

    International Nuclear Information System (INIS)

    Maurer, Heini; Staub, Lukas

    2012-09-01

    Maintaining constant Hydrogen levels in Nuclear power cycles is always associated with the challenge to determine the same reliably. Grab sample analysis is complicated and costly and online instruments currently known are difficult to maintain, verify and calibrate. Although amperometry has been proven to be the most suitable measuring principle for online instruments, it has never been thoroughly investigated what electrode materials would best perform in terms of measurement drift and regeneration requirements. This paper we will cover the findings of a research program, conducted at the R and D centre of Swan Analytische Instrumente AG in Hinwil Switzerland, aimed to find ideal electrode materials and sensor design to provide the nuclear industry with an enhanced method to determine dissolved hydrogen in nuclear power cycles. (authors)

  5. Nuclear power and the nuclear fuel cycle

    International Nuclear Information System (INIS)

    Scurr, I.F.; Silver, J.M.

    1990-01-01

    Australian Nuclear Science and Technology Organization maintains an ongoing assessment of the world's nuclear technology developments, as a core activity of its Strategic Plan. This publication reviews the current status of the nuclear power and the nuclear fuel cycle in Australia and around the world. Main issues discussed include: performances and economics of various types of nuclear reactors, uranium resources and requirements, fuel fabrication and technology, radioactive waste management. A brief account of the large international effort to demonstrate the feasibility of fusion power is also given. 11 tabs., ills

  6. Life cycle management at Ontario Power Generation

    International Nuclear Information System (INIS)

    Spekkens, P.

    2006-01-01

    This paper outlines the Life Cycle Management (LCM) program at Ontario Power Generation. LCM is carried out at different levels that includes components, systems, unit and fleet. A system involves cumulative effect of individual component aging. These components include steam generators, pressure tubes and feeders. A unit involves an overall unit aging strategy integrating all systems. At the fleet level, there is an optimal strategy for plant-level investments including end-of-life of a unit

  7. Irreversible thermodynamics of open chemical networks. I. Emergent cycles and broken conservation laws

    International Nuclear Information System (INIS)

    Polettini, Matteo; Esposito, Massimiliano

    2014-01-01

    In this paper and Paper II, we outline a general framework for the thermodynamic description of open chemical reaction networks, with special regard to metabolic networks regulating cellular physiology and biochemical functions. We first introduce closed networks “in a box”, whose thermodynamics is subjected to strict physical constraints: the mass-action law, elementarity of processes, and detailed balance. We further digress on the role of solvents and on the seemingly unacknowledged property of network independence of free energy landscapes. We then open the system by assuming that the concentrations of certain substrate species (the chemostats) are fixed, whether because promptly regulated by the environment via contact with reservoirs, or because nearly constant in a time window. As a result, the system is driven out of equilibrium. A rich algebraic and topological structure ensues in the network of internal species: Emergent irreversible cycles are associated with nonvanishing affinities, whose symmetries are dictated by the breakage of conservation laws. These central results are resumed in the relation a + b = s Y between the number of fundamental affinities a, that of broken conservation laws b and the number of chemostats s Y . We decompose the steady state entropy production rate in terms of fundamental fluxes and affinities in the spirit of Schnakenberg's theory of network thermodynamics, paving the way for the forthcoming treatment of the linear regime, of efficiency and tight coupling, of free energy transduction, and of thermodynamic constraints for network reconstruction

  8. Irreversible thermodynamics of open chemical networks. I. Emergent cycles and broken conservation laws.

    Science.gov (United States)

    Polettini, Matteo; Esposito, Massimiliano

    2014-07-14

    In this paper and Paper II, we outline a general framework for the thermodynamic description of open chemical reaction networks, with special regard to metabolic networks regulating cellular physiology and biochemical functions. We first introduce closed networks "in a box", whose thermodynamics is subjected to strict physical constraints: the mass-action law, elementarity of processes, and detailed balance. We further digress on the role of solvents and on the seemingly unacknowledged property of network independence of free energy landscapes. We then open the system by assuming that the concentrations of certain substrate species (the chemostats) are fixed, whether because promptly regulated by the environment via contact with reservoirs, or because nearly constant in a time window. As a result, the system is driven out of equilibrium. A rich algebraic and topological structure ensues in the network of internal species: Emergent irreversible cycles are associated with nonvanishing affinities, whose symmetries are dictated by the breakage of conservation laws. These central results are resumed in the relation a + b = s(Y) between the number of fundamental affinities a, that of broken conservation laws b and the number of chemostats s(Y). We decompose the steady state entropy production rate in terms of fundamental fluxes and affinities in the spirit of Schnakenberg's theory of network thermodynamics, paving the way for the forthcoming treatment of the linear regime, of efficiency and tight coupling, of free energy transduction, and of thermodynamic constraints for network reconstruction.

  9. The future of integrated coal gasification combined cycle power plants

    International Nuclear Information System (INIS)

    Mueller, R.; Termuehlen, H.

    1991-01-01

    This paper examines the future of integrated coal gasification combined cycle (IGCC) power plants as affected by various technical, economical and environmental trends in power generation. The topics of the paper include a description of natural gas-fired combined cycle power plants, IGCC plants, coal gasifier concepts, integration of gasifiers into combined cycle power plants, efficiency, environmental impacts, co-products of IGCC power plants, economics of IGCC power plants, and a review of IGCC power plant projects

  10. Integrated biomass pyrolysis with organic Rankine cycle for power generation

    Science.gov (United States)

    Nur, T. B.; Syahputra, A. W.

    2018-02-01

    The growing interest on Organic Rankine Cycle (ORC) application to produce electricity by utilizing biomass energy sources are increasingly due to its successfully used to generate power from waste heat available in industrial processes. Biomass pyrolysis is one of the thermochemical technologies for converting biomass into energy and chemical products consisting of liquid bio-oil, solid biochar, and pyrolytic gas. In the application, biomass pyrolysis can be divided into three main categories; slow, fast and flash pyrolysis mainly aiming at maximizing the products of bio-oil or biochar. The temperature of synthesis gas generated during processes can be used for Organic Rankine Cycle to generate power. The heat from synthesis gas during pyrolysis processes was transfer by thermal oil heater to evaporate ORC working fluid in the evaporator unit. In this study, the potential of the palm oil empty fruit bunch, palm oil shell, and tree bark have been used as fuel from biomass to generate electricity by integrated with ORC. The Syltherm-XLT thermal oil was used as the heat carrier from combustion burner, while R245fa was used as the working fluid for ORC system. Through Aspen Plus, this study analyses the influences on performance of main thermodynamic parameters, showing the possibilities of reaching an optimum performance for different working conditions that are characteristics of different design parameters.

  11. Thermodynamic analysis of Direct Urea Solid Oxide Fuel Cell in combined heat and power applications

    Science.gov (United States)

    Abraham, F.; Dincer, I.

    2015-12-01

    This paper presents a comprehensive steady state modelling and thermodynamic analysis of Direct Urea Solid Oxide Fuel Cell integrated with Gas Turbine power cycle (DU-SOFC/GT). The use of urea as direct fuel mitigates public health and safety risks associated with the use of hydrogen and ammonia. The integration scheme in this study covers both oxygen ion-conducting solid oxide fuel cells (SOFC-O) and hydrogen proton-conducting solid oxide fuel cells (SOFC-H). Parametric case studies are carried out to investigate the effects of design and operating parameters on the overall performance of the system. The results reveal that the fuel cell exhibited the highest level of exergy destruction among other system components. Furthermore, the SOFC-O based system offers better overall performance than that with the SOFC-H option mainly due to the detrimental reverse water-gas shift reaction at the SOFC anode as well as the unique configuration of the system.

  12. HESS Opinions "Biological catalysis of the hydrological cycle: life's thermodynamic function"

    Science.gov (United States)

    Michaelian, K.

    2012-08-01

    Darwinian theory depicts life as being overwhelmingly consumed by a fight for survival in a hostile environment. However, from a thermodynamic perspective, life is a dynamic, out of equilibrium process, stabilizing and coevolving in concert with its abiotic environment. The living components of the biosphere on the Earth's surface of greatest biomass, the plants and cyanobacteria, are involved in the transpiration of a vast amount of water. Transpiration is part of the global water cycle, and it is this cycle that distinguishes Earth from its apparently life-barren neighboring planets, Venus and Mars. The dissipation of sunlight into heat by organic molecules in the biosphere, and its coupling to the water cycle (as well as other abiotic processes), is by far the greatest entropy-producing process occurring on Earth. Life, from this perspective, can be viewed as performing an important thermodynamic function, acting as a dynamic catalyst by aiding irreversible abiotic processes such as the water cycle, hurricanes, and ocean and wind currents to produce entropy. The role of animals in this view is that of unwitting but dedicated servants of the plants and cyanobacteria, helping them to grow, and to spread into initially inhospitable areas.

  13. HESS Opinions "Biological catalysis of the hydrological cycle: life's thermodynamic function"

    Directory of Open Access Journals (Sweden)

    K. Michaelian

    2012-08-01

    Full Text Available Darwinian theory depicts life as being overwhelmingly consumed by a fight for survival in a hostile environment. However, from a thermodynamic perspective, life is a dynamic, out of equilibrium process, stabilizing and coevolving in concert with its abiotic environment. The living components of the biosphere on the Earth's surface of greatest biomass, the plants and cyanobacteria, are involved in the transpiration of a vast amount of water. Transpiration is part of the global water cycle, and it is this cycle that distinguishes Earth from its apparently life-barren neighboring planets, Venus and Mars. The dissipation of sunlight into heat by organic molecules in the biosphere, and its coupling to the water cycle (as well as other abiotic processes, is by far the greatest entropy-producing process occurring on Earth. Life, from this perspective, can be viewed as performing an important thermodynamic function, acting as a dynamic catalyst by aiding irreversible abiotic processes such as the water cycle, hurricanes, and ocean and wind currents to produce entropy. The role of animals in this view is that of unwitting but dedicated servants of the plants and cyanobacteria, helping them to grow, and to spread into initially inhospitable areas.

  14. Thermodynamic analysis of a Rankine cycle applied on a diesel truck engine using steam and organic medium

    International Nuclear Information System (INIS)

    Katsanos, C.O.; Hountalas, D.T.; Pariotis, E.G.

    2012-01-01

    Highlights: ► ORC improves bsfc from 10.7% to 8.4% as engine load increases from 25% to 100%. ► Increasing ORC high pressure increases thermodynamic efficiency and power output. ► Operating at high pressure the ORC is favorable for the engine cooling system. ► The low temperature values of the ORC favors heat extraction from the EGR gas. ► The impact of the exhaust gas heat exchanger on engine backpressure is limited. - Abstract: A theoretical study is conducted to investigate the potential improvement of the overall efficiency of a heavy-duty truck diesel engine equipped with a Rankine bottoming cycle for recovering heat from the exhaust gas. To this scope, a newly developed thermodynamic simulation model has been used, considering two different working media: water and the refrigerant R245ca. As revealed from the analysis, due to the variation of exhaust gas temperature with engine load it is necessary to modify the Rankine cycle parameters i.e. high pressure and superheated vapor temperature. For this reason, a new calculation procedure is applied for the estimation of the optimum Rankine cycle parameters at each operating condition. The calculation algorithm is conducted by taking certain design criteria into account, such as the exhaust gas heat exchanger size and its pinch point requirement. From the comparative evaluation between the two working media examined, using the optimum configuration of the cycle for each operating condition, it has been revealed that the brake specific fuel consumption improvement ranges from 10.2% (at 25% engine load) to 8.5% (at 100% engine load) for R245ca and 6.1% (at 25% engine load) to 7.5% (at 100% engine load) for water.

  15. Thermodynamic, energy efficiency, and power density analysis of reverse electrodialysis power generation with natural salinity gradients.

    Science.gov (United States)

    Yip, Ngai Yin; Vermaas, David A; Nijmeijer, Kitty; Elimelech, Menachem

    2014-05-06

    Reverse electrodialysis (RED) can harness the Gibbs free energy of mixing when fresh river water flows into the sea for sustainable power generation. In this study, we carry out a thermodynamic and energy efficiency analysis of RED power generation, and assess the membrane power density. First, we present a reversible thermodynamic model for RED and verify that the theoretical maximum extractable work in a reversible RED process is identical to the Gibbs free energy of mixing. Work extraction in an irreversible process with maximized power density using a constant-resistance load is then examined to assess the energy conversion efficiency and power density. With equal volumes of seawater and river water, energy conversion efficiency of ∼ 33-44% can be obtained in RED, while the rest is lost through dissipation in the internal resistance of the ion-exchange membrane stack. We show that imperfections in the selectivity of typical ion exchange membranes (namely, co-ion transport, osmosis, and electro-osmosis) can detrimentally lower efficiency by up to 26%, with co-ion leakage being the dominant effect. Further inspection of the power density profile during RED revealed inherent ineffectiveness toward the end of the process. By judicious early discontinuation of the controlled mixing process, the overall power density performance can be considerably enhanced by up to 7-fold, without significant compromise to the energy efficiency. Additionally, membrane resistance was found to be an important factor in determining the power densities attainable. Lastly, the performance of an RED stack was examined for different membrane conductivities and intermembrane distances simulating high performance membranes and stack design. By thoughtful selection of the operating parameters, an efficiency of ∼ 37% and an overall gross power density of 3.5 W/m(2) represent the maximum performance that can potentially be achieved in a seawater-river water RED system with low

  16. Thermodynamic evaluation of CHP (combined heat and power) plants integrated with installations of coal gasification

    International Nuclear Information System (INIS)

    Ziębik, Andrzej; Malik, Tomasz; Liszka, Marcin

    2015-01-01

    Integration of a CHP steam plant with an installation of coal gasification and gas turbine leads to an IGCC-CHP (integrated gasification combined cycle-combined heat and power). Two installations of coal gasification have been analyzed, i.e. pressurized entrained flow gasifier – case 1 and pressurized fluidized bed gasifier with CO_2 recirculation – case 2. Basing on the results of mathematical modelling of an IGCC-CHP plant, the algorithms of calculating typical energy indices have been derived. The following energy indices are considered, i.e. coefficient of heat performance and relative savings of chemical energy of fuels. The results of coefficients of heat performance are contained between 1.87 and 2.37. Values exceeding 1 are thermodynamically justified because the idea of cogeneration of heat and electricity based on combining cycles of the heat engine and heat pump the efficiency of which exceeds 1. Higher values concerning waste heat replace more thermodynamically effective sources of heat in CHP plants. Relative savings of the chemical energy of fuels are similar in both cases of IGCC-CHP plants and are contained between the lower value of the CHP (combined heat and power) plants fuelled with coal and higher value of CHP plants fired with natural gas. - Highlights: • Energy savings of fuel is an adequate measure of cogeneration. • Relative energy savings of IGCC-CHP is near the result of a gas and steam CHP. • COHP (coefficient of heat performance) can help to divide fuel between heat fluxes. • Higher values of COHP in the case of waste heat recovery result from the lower thermal parameters.

  17. Life cycle assessment integrated with thermodynamic analysis of bio-fuel options for solid oxide fuel cells.

    Science.gov (United States)

    Lin, Jiefeng; Babbitt, Callie W; Trabold, Thomas A

    2013-01-01

    A methodology that integrates life cycle assessment (LCA) with thermodynamic analysis is developed and applied to evaluate the environmental impacts of producing biofuels from waste biomass, including biodiesel from waste cooking oil, ethanol from corn stover, and compressed natural gas from municipal solid wastes. Solid oxide fuel cell-based auxiliary power units using bio-fuel as the hydrogen precursor enable generation of auxiliary electricity for idling heavy-duty trucks. Thermodynamic analysis is applied to evaluate the fuel conversion efficiency and determine the amount of fuel feedstock needed to generate a unit of electrical power. These inputs feed into an LCA that compares energy consumption and greenhouse gas emissions of different fuel pathways. Results show that compressed natural gas from municipal solid wastes is an optimal bio-fuel option for SOFC-APU applications in New York State. However, this methodology can be regionalized within the U.S. or internationally to account for different fuel feedstock options. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Performance analysis of a combined organic Rankine cycle and vapor compression cycle for power and refrigeration cogeneration

    International Nuclear Information System (INIS)

    Kim, Kyoung Hoon; Perez-Blanco, Horacio

    2015-01-01

    A thermodynamic analysis of cogeneration of power and refrigeration activated by low-grade sensible energy is presented in this work. An organic Rankine cycle (ORC) for power production and a vapor compression cycle (VCC) for refrigeration using the same working fluid are linked in the analysis, including the limiting case of cold production without net electricity production. We investigate the effects of key parameters on system performance such as net power production, refrigeration, and thermal and exergy efficiencies. Characteristic indexes proportional to the cost of heat exchangers or of turbines, such as total number of transfer units (NTU tot ), size parameter (SP) and isentropic volumetric flow ratio (VFR) are also examined. Three important system parameters are selected, namely turbine inlet temperature, turbine inlet pressure, and the flow division ratio. The analysis is conducted for several different working fluids. For a few special cases, isobutane is used for a sensitivity analysis due to its relatively high efficiencies. Our results show that the system has the potential to effectively use low grade thermal sources. System performance depends both on the adopted parameters and working fluid. - Highlights: • Waste heat utilization can reduce emissions of carbon dioxide. • The ORC/VCC cycle can deliver power and/or refrigeration using waste heat. • Efficiencies and size parameters are used for cycle evaluation. • The cycle performance is studied for eight suitable refrigerants. Isobutane is used for a sensitivity analysis. • The work shows that the isobutene cycle is quite promising.

  19. Modeling of a combined cycle power plant

    International Nuclear Information System (INIS)

    Faridah Mohamad Idris

    2001-01-01

    The combined cycle power plant is a non-linear, closed loop system, which consists of high-pressure (HP) superheater, HP evaporator, HP economizer, low-pressure (LP) evaporator, HP drum, HP deaerator, condenser, HP and LP steam turbine and gas turbine. The two types of turbines in the plant for example the gas turbine and the HP and LP steam turbines operate concurrently to generate power to the plant. The exhaust gas which originate from the combustion chamber drives the gas turbine, after which it flows into the heat recovery steam generator (HRSG) to generate superheated steam to be used in driving the HP and LP steam turbines. In this thesis, the combined cycle power plant is modeled at component level using the physical method. Assuming that there is delay in transport, except for the gas turbine system, the mass and heat balances are applied on the components of the plant to derive the governing equations of the components. These time dependent equations, which are of first order differential types, are then solved for the mass and enthalpy of the components. The solutions were simulated using Matlab Simulink using measured plant data. Where necessary there is no plant data available, approximated data were used. The generalized regression neural networks are also used to generate extra sets of simulation data for the HRSG system. Comparisons of the simulation results with its corresponding plant data showed good agreements between the two and indicated that the models developed for the components could be used to represent the combined cycle power plant under study. (author)

  20. 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.

  1. Thermodynamic control-oriented modeling of cycle-to-cycle exhaust gas temperature in an HCCI engine

    International Nuclear Information System (INIS)

    Dehghani Firoozabadi, M.; Shahbakhti, M.; Koch, C.R.; Jazayeri, S.A.

    2013-01-01

    Highlights: • First thermodynamic model in the literature to predict exhaust temperature in HCCI engines. • The model can be used for integrated control of HCCI combustion and exhaust temperature. • The model is experimentally validated at over 300 steady state and transient conditions. • Results show a good agreement between predicted and measured exhaust temperatures. • Sensitivity of exhaust gas temperature to variation of engine variables is shown. - Abstract: Model-based control of Homogenous Charge Compression Ignition (HCCI) engine exhaust temperature is a viable solution to optimize efficiency of both engine and the exhaust aftertreatment system. Low exhaust temperature in HCCI engines can limit the abatement of hydrocarbon (HC) and carbon monoxide (CO) emissions in an exhaust aftertreatment system. A physical–empirical model is described for control of exhaust temperature in HCCI engines. This model captures cycle-to-cycle dynamics affecting exhaust temperature and is based on thermodynamic relations and semi-empirical correlations. It incorporates intake and exhaust gas flow dynamics, residual gas mixing, and fuel burn rate and is validated with experimental data from a single cylinder engine at over 300 steady state and transient conditions. The validation results indicate a good agreement between predicted and measured exhaust gas temperature

  2. A Thermodynamic Analysis of Two Competing Mid-Sized Oxyfuel Combustion Combined Cycles

    Directory of Open Access Journals (Sweden)

    Egill Thorbergsson

    2016-01-01

    Full Text Available A comparative analysis of two mid-sized oxyfuel combustion combined cycles is performed. The two cycles are the semiclosed oxyfuel combustion combined cycle (SCOC-CC and the Graz cycle. In addition, a reference cycle was established as the basis for the analysis of the oxyfuel combustion cycles. A parametric study was conducted where the pressure ratio and the turbine entry temperature were varied. The layout and the design of the SCOC-CC are considerably simpler than the Graz cycle while it achieves the same net efficiency as the Graz cycle. The fact that the efficiencies for the two cycles are close to identical differs from previously reported work. Earlier studies have reported around a 3% points advantage in efficiency for the Graz cycle, which is attributed to the use of a second bottoming cycle. This additional feature is omitted to make the two cycles more comparable in terms of complexity. The Graz cycle has substantially lower pressure ratio at the optimum efficiency and has much higher power density for the gas turbine than both the reference cycle and the SCOC-CC.

  3. The Carnot cycle and the teaching of thermodynamics: a historical approach

    Science.gov (United States)

    Laranjeiras, Cássio C.; Portela, Sebastião I. C.

    2016-09-01

    The Carnot cycle is a topic that is traditionally present in introductory physics courses dedicated to the teaching of thermodynamics, playing an essential role in introducing the concept of Entropy and the consequent formulation of the second Law. Its effective understanding and contribution to the development of thermodynamics is often hindered, however. Among other things, this is the result of a pragmatic approach, which usually limits itself to presenting the isotherms and adiabatic curves in a P-V diagram and is totally disconnected from the historical fundamentals of Heat Theory. The purpose of this paper is to reveal the potential of an approach to the subject that recovers the historical and social dimensions of scientific knowledge, and to promote reflections about the nature of science (NOS).

  4. Análise termodinâmica de um ciclo de potência com célula a combustível sofc e turbina a vapor = Thermodynamic analysis of a power cycle such as SOFC fuel cell and steam turbine

    Directory of Open Access Journals (Sweden)

    Alexandre Sordi

    2006-01-01

    Full Text Available O objetivo deste artigo foi realizar a análise termodinâmica de um sistema híbrido, SOFC / ST (célula a combustível tipo SOFC e turbina a vapor ST. O combustível considerado para a análise foi o gás metano (biogás produzido por meio da digestão anaeróbica de resíduos orgânicos. A metodologia utilizada foi o balanço de energia dosistema SOFC / ST, considerando a reforma interna do metano na célula a combustível, de forma a obter a sua eficiência elétrica. O resultado foi comparado a um ciclo combinado convencional de turbina a gás e turbina a vapor (GT / ST para potências entre 10 MW e 30MW. A eficiência do sistema híbrido SOFC / ST variou de 61% a 66% em relação ao poder calorífico do metano; e a eficiência do ciclo combinado GT / ST variou de 41% a 55% para o mesmo intervalo de potência. Para geração distribuída a célula a combustível SOFC é atecnologia mais eficiente.The objective of this article was to analyze the thermodynamic of ahybrid system, SOFC / ST (SOFC fuel cell and ST steam turbine. The fuel for the analysis was the gas methane (biogas produced through the anaerobic digestion of the organic residues. The utilized methodology was the energy balance of the system SOFC / ST,considering the internal reforming of methane in the fuel cell, in a way to obtain its electric effectiveness. The result was compared to a conventional combined cycle of gas turbine and steam turbine (GT / ST for powers between 10 MW and 30 MW. The efficiency of the hybrid system SOFC / ST varied from 61 to 66% in relation to the lower heating value of methane; and the efficiency of the combined cycle GT / ST varied from 41 to 55% within the same power interval. For distributed generation, the SOFC fuel cell is the most efficienttechnology.

  5. Magnetic refrigeration cycle analysis using selected thermodynamic property characterizations for gadolinium gallium garnet

    International Nuclear Information System (INIS)

    Murphy, R.W.

    1992-01-01

    Magneto-thermodynamic property characterizations were selected, adapted, and compared to material property data for gadolinium gallium garnet in the temperature range 4--40 K and magnetic field range 0--6 T. The most appropriate formulations were incorporated into a model in which methods similar to those previously developed for other materials and temperature ranges were used to make limitation and relative performance assessments of Carnot, ideal regenerative, and pseudo-constant field regenerative cycles. Analysis showed that although Carnot cycle limitations on available temperature lift for gadolinium gallium garnet are not as severe as those for materials previously examined, substantial improvements in cooling capacity/temperature lift combinations can be achieved using regenerative cycles within specified fields limits if significant loss mechanisms are mitigated

  6. Thermodynamic analysis and optimization of IT-SOFC-based integrated coal gasification fuel cell power plants

    NARCIS (Netherlands)

    Romano, M.C.; Campanari, S.; Spallina, V.; Lozza, G.

    2011-01-01

    This work discusses the thermodynamic analysis of integrated gasification fuel cell plants, where a simple cycle gas turbine works in a hybrid cycle with a pressurized intermediate temperature–solid oxide fuel cell (SOFC), integrated with a coal gasification and syngas cleanup island and a bottoming

  7. Thermodynamic analysis and preliminary design of closed Brayton cycle using nitrogen as working fluid and coupled to small modular Sodium-cooled fast reactor (SM-SFR)

    International Nuclear Information System (INIS)

    Olumayegun, Olumide; Wang, Meihong; Kelsall, Greg

    2017-01-01

    Highlights: • Nitrogen closed Brayton cycle for small modular sodium-cooled fast reactor studied. • Thermodynamic modelling and analysis of closed Brayton cycle performed. • Two-shaft configuration proposed and performance compared to single shaft. • Preliminary design of heat exchangers and turbomachinery carried out. - Abstract: Sodium-cooled fast reactor (SFR) is considered the most promising of the Generation IV reactors for their near-term demonstration of power generation. Small modular SFRs (SM-SFRs) have less investment risk, can be deployed more quickly, are easier to operate and are more flexible in comparison to large nuclear reactor. Currently, SFRs use the proven Rankine steam cycle as the power conversion system. However, a key challenge is to prevent dangerous sodium-water reaction that could happen in SFR coupled to steam cycle. Nitrogen gas is inert and does not react with sodium. Hence, intercooled closed Brayton cycle (CBC) using nitrogen as working fluid and with a single shaft configuration has been one common power conversion system option for possible near-term demonstration of SFR. In this work, a new two shaft nitrogen CBC with parallel turbines was proposed to further simplify the design of the turbomachinery and reduce turbomachinery size without compromising the cycle efficiency. Furthermore, thermodynamic performance analysis and preliminary design of components were carried out in comparison with a reference single shaft nitrogen cycle. Mathematical models in Matlab were developed for steady state thermodynamic analysis of the cycles and for preliminary design of the heat exchangers, turbines and compressors. Studies were performed to investigate the impact of the recuperator minimum terminal temperature difference (TTD) on the overall cycle efficiency and recuperator size. The effect of turbomachinery efficiencies on the overall cycle efficiency was examined. The results showed that the cycle efficiency of the proposed

  8. A point of view on Otto cycle approach specific for an undergraduate thermodynamics course in CMU

    Science.gov (United States)

    Memet, F.; Preda, A.

    2015-11-01

    This paper refers to the description of the way in which can be presented to future marine engineers the analyzis of the performance of an Otto cycle, in a manner which is beyond the classic approach of the course of thermodynamics in Constanta Maritime University. The conventional course of thermodynamics is dealing with the topic of performance analysis of the cycle of the internal combustion engine with isochoric combustion for the situation in which the working medium is treated as such a perfect gas. This type of approach is viable only when are considered relatively small temperature differences. But this is the situation when specific heats are seen as constant. Instead, the practical experience has shown that small temperature differences are not viable, resulting the need for variable specific heat evaluation. The presentation bellow is available for the adiabatic exponent written as a liniar function depending on temperature. In the section of this paper dedicated to methods and materials, the situation in which the specific heat is taken as constant is not neglected, additionaly being given the algorithm for variable specific heat.For the both cases it is given the way in which it is assessed the work output. The calculus is based on the cycle shown in temperature- entropy diagram, in which are also indicated the irreversible adiabatic compression and expansion. The experience achieved after understanding this theory will allow to future professionals to deal successfully with the design practice of internal combustion engines.

  9. Thermodynamic evaluation of geothermal energy powered hydrogen production by PEM water electrolysis

    International Nuclear Information System (INIS)

    Yilmaz, Ceyhun; Kanoglu, Mehmet

    2014-01-01

    Thermodynamic energy and exergy analysis of a PEM water electrolyzer driven by geothermal power for hydrogen production is performed. For this purpose, work is produced from a geothermal resource by means of the organic Rankine cycle; the resulting work is used as a work input for an electrolysis process; and electrolysis water is preheated by the waste geothermal water. The first and second-law based performance parameters are identified for the considered system and the system performance is evaluated. The effects of geothermal water and electrolysis temperatures on the amount of hydrogen production are studied and these parameters are found to be proportional to each other. We consider a geothermal resource at 160 °C available at a rate of 100 kg/s. Under realistic operating conditions, 3810 kW power can be produced in a binary geothermal power plant. The produced power is used for the electrolysis process. The electrolysis water can be preheated to 80 °C by the geothermal water leaving the power plant and hydrogen can be produced at a rate of 0.0340 kg/s. The energy and exergy efficiencies of the binary geothermal power plant are 11.4% and 45.1%, respectively. The corresponding efficiencies for the electrolysis system are 64.0% and 61.6%, respectively, and those for the overall system are 6.7% and 23.8%, respectively. - Highlights: • Thermodynamic analysis of hydrogen production by PEM electrolysis powered by geothermal energy. • Power is used for electrolyser; used geothermal water is for preheating electrolysis water. • Effect of geothermal water and electrolysis temperatures on the amount of hydrogen production. • Hydrogen can be produced at a rate of 0.0340 kg/s for a resource at 160 °C available at 100 kg/s. • Energy and exergy efficiencies of the overall system are 6.7% and 23.8%, respectively

  10. Anammox revisited: thermodynamic considerations in early studies of the microbial nitrogen cycle.

    Science.gov (United States)

    Oren, Aharon

    2015-08-01

    This paper explores the early literature on the thermodynamics of processes in the microbial nitrogen cycle, evaluating parameters of transfer of energy which depends on the initial and final states of the system, the mechanism of the reactions involved and the rates of these reactions. Processes discussed include the anaerobic oxidation of ammonium (the anammox reaction), the use of inorganic nitrogen compounds as electron donors for anoxygenic photosynthesis, and the mechanism and bioenergetics of biological nitrogen fixation. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. Thermodynamic analysis and system design of a novel split cycle engine concept

    International Nuclear Information System (INIS)

    Dong, Guangyu; Morgan, Robert E.; Heikal, Morgan R.

    2016-01-01

    The split cycle engine is a new reciprocating internal combustion engine with a potential of a radical efficiency improvement. In this engine, the compression and combustion–expansion processes occur in different cylinders. In the compression cylinder, the charge air is compressed through a quasi-isothermal process by direct cooling of the air. The high pressure air is then heated in a recuperator using the waste heat of exhaust gas before induction to the combustion cylinder. The combustion process occurs during the expansion stroke, in a quasi-isobaric process. In this paper, a fundamental theoretical cycle analysis and one-dimensional engine simulation of the split cycle engine was undertaken. The results show that the thermal efficiency (η) is mainly decided by the CR (compression ratio) and ER (expansion ratio), the regeneration effectiveness (σ), and the temperature rising ratio (N). Based on the above analysis, a system optimization of the engine was conducted. The results showed that by increasing CR from 23 to 25, the combustion and recuperation processes could be improved. By increasing the expansion ratio to 26, the heat losses during the gas exchange stroke were further reduced. Furthermore, the coolant temperatures of the compression and expansion chambers can be controlled separately to reduce the wall heat transfer losses. Compared to a conventional engine, a 21% total efficiency improvement was achieved when the split cycle was applied. It was concluded that through the system optimization, a total thermal efficiency of 53% can be achieved on split cycle engine. - Highlights: • Fundamental mechanism of the split cycle engine is investigated. • The key affecting factors of the thermodynamic cycle efficiency are identified. • The practical efficiency of split cycle applying on diesel engine is analysed. • The design optimization on the split cycle engine concept is conducted.

  12. Thermodynamic modeling of the power plant based on the SOFC with internal steam reforming of methane

    International Nuclear Information System (INIS)

    Ivanov, Peter

    2007-01-01

    Mathematical model based on the thermodynamic modeling of gaseous mixtures is developed for SOFC with internal steam reforming of methane. Macroscopic porous-electrode theory, including non-linear kinetics and gas-phase diffusion, is used to calculate the reforming reaction and the concentration polarization. Provided the data concerning properties and costs of materials the model is fit for wide range of parametric analysis of thermodynamic cycles including SOFC

  13. Thermodynamic analysis of an integrated solid oxide fuel cell cycle with a rankine cycle

    International Nuclear Information System (INIS)

    Rokni, Masoud

    2010-01-01

    Hybrid systems consisting of solid oxide fuel cells (SOFC) on the top of a steam turbine (ST) are investigated. The plants are fired by natural gas (NG). A desulfurization reactor removes the sulfur content in the fuel while a pre-reformer breaks down the heavier hydro-carbons. The pre-treated fuel enters then into the anode side of the SOFC. The remaining fuels after the SOFC stacks enter a burner for further burning. The off-gases are then used to produce steam for a Rankine cycle in a heat recovery steam generator (HRSG). Different system setups are suggested. Cyclic efficiencies up to 67% are achieved which is considerably higher than the conventional combined cycles (CC). Both adiabatic steam reformer (ASR) and catalytic partial oxidation (CPO) fuel pre-reformer reactors are considered in this investigation.

  14. Experimental Study of a Low-Temperature Power Generation System in an Organic Rankine Cycle

    DEFF Research Database (Denmark)

    Mu, Yongchao; Zhang, Yufeng; Deng, Na

    2015-01-01

    This paper presents a new power generation system under the principle of organic Rankine cycle which can generate power with a low-temperature heat source. A prototype was built to investigate the proposed system. In the prototype, an air screw compressor was converted into an expander and used...... as the engine of the power generator. The style of the preheater was a shell and tube heat exchanger, which could provide a long path for the working fluid. A flooded heat exchanger with a high heat transfer coefficient was taken as the evaporator. R134a was used as working fluid for the Rankine cycle......, the average isentropic efficiency of the screw expander was 68%, and the efficiency of power generation varies from 1.2 to 4.56%. The highest value of thermodynamical perfectness was 29.06%. It can be concluded that organic Rankine cycle could be competitive for recovering low-temperature heat source...

  15. The thermodynamics of pyrochemical processes for liquid metal reactor fuel cycles

    International Nuclear Information System (INIS)

    Johnson, I.

    1987-01-01

    The thermodynamic basis for pyrochemical processes for the recovery and purification of fuel for the liquid metal reactor fuel cycle is described. These processes involve the transport of the uranium and plutonium from one liquid alloy to another through a molten salt. The processes discussed use liquid alloys of cadmium, zinc, and magnesium and molten chloride salts. The oxidation-reduction steps are done either chemically by the use of an auxiliary redox couple or electrochemically by the use of an external electrical supply. The same basic thermodynamics apply to both the salt transport and the electrotransport processes. Large deviations from ideal solution behavior of the actinides and lanthanides in the liquid alloys have a major influence on the solubilities and the performance of both the salt transport and electrotransport processes. Separation of plutonium and uranium from each other and decontamination from the more noble fission product elements can be achieved using both transport processes. The thermodynamic analysis is used to make process design computations for different process conditions

  16. Thermodynamic evaluation of solar-geothermal hybrid power plants in northern Chile

    International Nuclear Information System (INIS)

    Cardemil, José Miguel; Cortés, Felipe; Díaz, Andrés; Escobar, Rodrigo

    2016-01-01

    Highlights: • Thermodynamic evaluation of geothermal-solar hybrid systems. • A multi-parameter analysis for different cycle configurations. • Performance comparison between two operation modes. • Overview of the technical applicability of the hybridization. - Abstract: A thermodynamic model was developed using Engineering Equation Solver (EES) to evaluate the performance of single and double-flash geothermal power plants assisted by a parabolic trough solar concentrating collector field, considering four different geothermal reservoir conditions. The benefits of delivering solar thermal energy for either the superheating or evaporating processes were analyzed in order to achieve the maximum 2"n"d law efficiency for the hybrid schemes and reduce the geothermal resource consumption for a constant power production. The results of the hybrid single-flash demonstrate that the superheating process generates additional 0.23 kWe/kWth, while supplying solar heat to evaporate the geothermal brine only delivers 0.16 kWe/kWth. The double-flash hybrid plant simulation results allow obtaining 0.29 kWe/kWth and 0.17 kW/kWth by integrating solar energy at the superheater and evaporator, respectively. In this context, the hybrid single-flash power plant is able to produce at least 20% additional power output, depending on the characteristics of the geothermal resource. Moreover, all of the cases analyzed herein increased the exergy efficiency of the process by at least 3%. The developed model also allowed assessing the reduction on the consumption of the geothermal fluid from the reservoir when the plant power output stays constant, up to 16% for the hybrid single-flash, and 19% for the hybrid double-flash. Based on the results obtained in this study, the solar-geothermal hybrid scheme increases the power generation compared with geothermal-only power plants, being an attractive solution for improved management of the geothermal reservoir depletion rates. The study shows

  17. Analysis and optimization of three main organic Rankine cycle configurations using a set of working fluids with different thermodynamic behaviors

    Science.gov (United States)

    Hamdi, Basma; Mabrouk, Mohamed Tahar; Kairouani, Lakdar; Kheiri, Abdelhamid

    2017-06-01

    Different configurations of organic Rankine cycle (ORC) systems are potential thermodynamic concepts for power generation from low grade heat. The aim of this work is to investigate and optimize the performances of the three main ORC systems configurations: basic ORC, ORC with internal heat exchange (IHE) and regenerative ORC. The evaluation for those configurations was performed using seven working fluids with typical different thermodynamic behaviours (R245fa, R601a, R600a, R227ea, R134a, R1234ze and R1234yf). The optimization has been performed using a genetic algorithm under a comprehensive set of operative parameters such as the fluid evaporating temperature, the fraction of flow rate or the pressure at the steam extracting point in the turbine. Results show that there is no general best ORC configuration for all those fluids. However, there is a suitable configuration for each fluid. Contribution to the topical issue "Materials for Energy harvesting, conversion and storage II (ICOME 2016)", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  18. Thermodynamic optimisation and analysis of four Kalina cycle layouts for high temperature applications

    International Nuclear Information System (INIS)

    Modi, Anish; Haglind, Fredrik

    2015-01-01

    The Kalina cycle has seen increased interest in the last few years as an efficient alternative to the conventional steam Rankine cycle. However, the available literature gives little information on the algorithms to solve or optimise this inherently complex cycle. This paper presents a detailed approach to solve and optimise a Kalina cycle for high temperature (a turbine inlet temperature of 500 °C) and high pressure (over 100 bar) applications using a computationally efficient solution algorithm. A central receiver solar thermal power plant with direct steam generation was considered as a case study. Four different layouts for the Kalina cycle based on the number and/or placement of the recuperators in the cycle were optimised and compared based on performance parameters such as the cycle efficiency and the cooling water requirement. The cycles were modelled in steady state and optimised with the maximisation of the cycle efficiency as the objective function. It is observed that the different cycle layouts result in different regions for the optimal value of the turbine inlet ammonia mass fraction. Out of the four compared layouts, the most complex layout KC1234 gives the highest efficiency. The cooling water requirement is closely related to the cycle efficiency, i.e., the better the efficiency, the lower is the cooling water requirement. - Highlights: • Detailed methodology for solving and optimising Kalina cycle for high temperature applications. • A central receiver solar thermal power plant with direct steam generation considered as a case study. • Four Kalina cycle layouts based on the placement of recuperators optimised and compared

  19. Thermodynamic Analysis of an Integrated Solid Oxide Fuel Cell Cycle with a Rankine Cycle

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2010-01-01

    Hybrid systems consisting of Solid Oxide Fuel Cells (SOFC) on the top of a Steam Turbine (ST) are investigated. The plants are fired by natural gas (NG). A desulfurization reactor removes the sulfur content in the fuel while a pre-reformer breaks down the heavier hydrocarbons. The pre-treated fuel......% are achieved which is considerably higher than the conventional Combined Cycles (CC). Both ASR (Adiabatic Steam Reformer) and CPO (Catalytic Partial Oxidation) fuel pre-reformer reactors are considered in this investigation....

  20. Power and efficiency optimization for combined Brayton and inverse Brayton cycles

    International Nuclear Information System (INIS)

    Zhang Wanli; Chen Lingen; Sun Fengrui

    2009-01-01

    A thermodynamic model for open combined Brayton and inverse Brayton cycles is established considering the pressure drops of the working fluid along the flow processes and the size constraints of the real power plant using finite time thermodynamics in this paper. There are 11 flow resistances encountered by the gas stream for the combined Brayton and inverse Brayton cycles. Four of these, the friction through the blades and vanes of the compressors and the turbines, are related to the isentropic efficiencies. The remaining flow resistances are always present because of the changes in flow cross-section at the compressor inlet of the top cycle, combustion inlet and outlet, turbine outlet of the top cycle, turbine outlet of the bottom cycle, heat exchanger inlet, and compressor inlet of the bottom cycle. These resistances control the air flow rate and the net power output. The relative pressure drops associated with the flow through various cross-sectional areas are derived as functions of the compressor inlet relative pressure drop of the top cycle. The analytical formulae about the relations between power output, thermal conversion efficiency, and the compressor pressure ratio of the top cycle are derived with the 11 pressure drop losses in the intake, compression, combustion, expansion, and flow process in the piping, the heat transfer loss to the ambient, the irreversible compression and expansion losses in the compressors and the turbines, and the irreversible combustion loss in the combustion chamber. The performance of the model cycle is optimized by adjusting the compressor inlet pressure of the bottom cycle, the air mass flow rate and the distribution of pressure losses along the flow path. It is shown that the power output has a maximum with respect to the compressor inlet pressure of the bottom cycle, the air mass flow rate or any of the overall pressure drops, and the maximized power output has an additional maximum with respect to the compressor pressure

  1. Thermodynamic performance optimization of the absorption-generation process in an absorption refrigeration cycle

    International Nuclear Information System (INIS)

    Chen, Yi; Han, Wei; Jin, Hongguang

    2016-01-01

    Highlights: • This paper proposes a new thermal compressor model with boost pressure ratio. • The proposed model is an effective way to optimize the absorption-generation process. • Boost pressure ratio is a key parameter in the proposed thermal compressor model. • The optimum boost pressure ratios for two typical refrigeration systems are obtained. - Abstract: The absorption refrigeration cycle is a basic cycle that establishes the systems for utilizing mid-low temperature heat sources. A new thermal compressor model with a key parameter of boost pressure ratio is proposed to optimize the absorption-generation process. The ultimate generation pressure and boost pressure ratio are used to represent the potential and operating conditions of the thermal compressor, respectively. Using the proposed thermal compressor model, the operation mechanism and requirements of the absorption refrigeration system and absorption-compression refrigeration system are elucidated. Furthermore, the two typical heat conversion systems are optimized based on the thermal compressor model. The optimum boost pressure ratios of the absorption refrigeration system and the absorption-compression refrigeration system are 0.5 and 0.75, respectively. For the absorption refrigeration system, the optimum generation temperature is 125.31 °C at the cooling water temperature of 30 °C, which is obtained by simple thermodynamic calculation. The optimized thermodynamic performance of the absorption-compression refrigeration system is 16.7% higher than that of the conventional absorption refrigeration system when the generation temperature is 100 °C. The thermal compressor model proposed in this paper is an effective method for simplifying the optimization of the thermodynamic systems involving an absorption-generation process.

  2. Land use impact evaluation in life cycle assessment based on ecosystem thermodynamics

    International Nuclear Information System (INIS)

    Wagendorp, Tim; Gulinck, Hubert; Coppin, Pol; Muys, Bart

    2006-01-01

    Life Cycle Assessment (LCA) studies of products with a major part of their life cycle in biological production systems (i.e. forestry and agriculture) are often incomplete because the assessment of the land use impact is not operational. Most method proposals include the quality of the land in a descriptive way using rank scores for an arbitrarily selected set of indicators. This paper first offers a theoretical framework for the selection of suitable indicators for land use impact assessment, based on ecosystem thermodynamics. According to recent theories on the thermodynamics of open systems, a goal function of ecosystems is to maximize the dissipation of exogenic exergy fluxes by maximizing the internal exergy storage under form of biomass, biodiversity and complex trophical networks. Human impact may decrease this ecosystem exergy level by simplification, i.e. decreasing biomass and destroying internal complexity. Within this theoretical framework, we then studied possibilities for assessing the land use impact in a more direct way by measuring the ecosystems' capacity to dissipate solar exergy. Measuring ecosystem thermal characteristics by using remote sensing techniques was considered a promising tool. Once operational, it could offer a quick and cheap alternative to quantify land use impacts in any terrestrial ecosystem of any size. Recommendations are given for further exploration of this method and for its integration into an ISO compatible LCA framework

  3. Thermodynamic analysis of a refrigeration cycle using regenerative heat exchanger - suction/liquid line

    Energy Technology Data Exchange (ETDEWEB)

    Tebchirani, Tarik Linhares; Matos, Rudmar Serafim [Pos graduate Programme in Mechanical Engineering (PGMEC), Universidade Federal do Parana, Curitiba, PR (Brazil)], e-mails: tarik@utfpr.edu.br, rudmar@demec.ufpr.br

    2010-07-01

    This paper presents results from thermodynamic comparison of a conventional compression cycle and a steam cycle that uses a heat exchanger countercurrent (liquid line/suction line) in an air conditioning system split. The main objective is to study the relationship between the COP and the mass variation of refrigerant to the effectiveness of the heat exchanger. The papers presented in the literature discuss the matter in a theoretical way, are summarized in tables of rare loss statements without specification of methods. The methodology of work is based on testing of an air conditioner operating conventionally and also with the heat exchanger for the determination of values and parameters of interest. The tests were performed in a thermal chamber with temperature controlled and equipped with a data acquisition system for reading and storage results. The refrigerant was R22. Besides making possible an assessment of the feasibility of cost-benefit thermodynamics, it is suggested a different method for installing the equipment type split. (author)

  4. Working fluid selection for the Organic Rankine Cycle (ORC) exhaust heat recovery of an internal combustion engine power plant

    Science.gov (United States)

    Douvartzides, S.; Karmalis, I.

    2016-11-01

    Organic Rankine cycle technology is capable to efficiently convert low-grade heat into useful mechanical power. In the present investigation such a cycle is used for the recovery of heat from the exhaust gases of a four stroke V18 MAN 51/60DF internal combustion engine power plant operating with natural gas. Design is focused on the selection of the appropriate working fluid of the Rankine cycle in terms of thermodynamic, environmental and safety criteria. 37 candidate fluids have been considered and all Rankine cycles examined were subcritical. The thermodynamic analysis of all fluids has been comparatively undertaken and the effect of key operation conditions such as the evaporation pressure and the superheating temperature was taken into account. By appropriately selecting the working fluid and the Rankine cycle operation conditions the overall plant efficiency was improved by 5.52% and fuel consumption was reduced by 12.69%.

  5. Thermodynamic analysis of PBMR plant

    International Nuclear Information System (INIS)

    Sen, S.; Kadiroglu, O.K.

    2002-01-01

    The thermodynamic analysis of a PBMR is presented for various pressures and temperatures values. The design parameters of the components of the power plant are calculated and an optimum cycle for the maximum thermal efficiency is sought for. (author)

  6. Thermodynamics Properties of Binary Gas Mixtures for Brayton Space Nuclear Power System

    International Nuclear Information System (INIS)

    You Ersheng; Shi Lei; Zhang Zuoyi

    2014-01-01

    Space nuclear power system with closed Brayton cycle has the potential advantages of high cycle efficiency. It can be achieved to limit the specific mass of the system with a competitive design scheme, so as to strengthen the advantage of the nuclear energy applying in space propulsion and electric generating compared to solar or chemical propellant. Whereby, the thermodynamic properties of working fluids have a significant influence on the performance of the plant. Therefore, two binary mixtures helium-nitrogen and helium-carbon dioxide are introduced to analysis the variation in the transport and heat transfer capacity of working fluids. Based on the parameters of pure gases, the heat transfer coefficient, pressure losses and aerodynamic loading are calculated as a function of mole fraction at the temperature of 400 K and 1200 K, as well as the typical operating pressure of 2 MPa. Results indicated that the mixture of helium-carbon dioxide with a mole fraction of 0.4 is a more attractive choice for the high heat transfer coefficient, low aerodynamic loading and acceptable pressure losses in contrast to helium-nitrogen and other mixing ratios of helium-carbon dioxide. Its heat transfer coefficient is almost 20% more than that of pure helium and the normalized aerodynamic loading is less than 34% at 1200 K. However; the pressure losses are a little higher with ~3.5 times those of pure helium. (author)

  7. Thermodynamic analysis and optimization of an irreversible Ericsson cryogenic refrigerator cycle

    International Nuclear Information System (INIS)

    Ahmadi, Mohammad Hossein; Ahmadi, Mohammad Ali

    2015-01-01

    Highlights: • Thermodynamic modeling of Ericsson refrigeration is performed. • The latter is achieved using NSGA algorithm and thermodynamic analysis. • Different decision makers are utilized to determine optimum values of outcomes. - Abstract: Optimum ecological and thermal performance assessments of an Ericsson cryogenic refrigerator system are investigated in different optimization settings. To evaluate this goal, ecological and thermal approaches are proposed for the Ericsson cryogenic refrigerator, and three objective functions (input power, coefficient of performance and ecological objective function) are gained for the suggested system. Throughout the current research, an evolutionary algorithm (EA) and thermodynamic analysis are employed to specify optimum values of the input power, coefficient of performance and ecological objective function of an Ericsson cryogenic refrigerator system. Four setups are assessed for optimization of the Ericsson cryogenic refrigerator. Throughout the three scenarios, a conventional single-objective optimization has been utilized distinctly with each objective function, nonetheless of other objectives. Throughout the last setting, input power, coefficient of performance and ecological function objectives are optimized concurrently employing a non-dominated sorting genetic algorithm (GA) named the non-dominated sorting genetic algorithm (NSGA-II). As in multi-objective optimization, an assortment of optimum results named the Pareto optimum frontiers are gained rather than a single ultimate optimum result gained via conventional single-objective optimization. Thus, a process of decision making has been utilized for choosing an ultimate optimum result. Well-known decision-makers have been performed to specify optimized outcomes from the Pareto optimum results in the space of objectives. The outcomes gained from aforementioned optimization setups are discussed and compared employing an index of deviation presented in this

  8. Thermodynamic simulation of a multi-step externally fired gas turbine powered by biomass

    International Nuclear Information System (INIS)

    Durante, A.; Pena-Vergara, G.; Curto-Risso, P.L.; Medina, A.; Calvo Hernández, A.

    2017-01-01

    Highlights: • A realistic model for an EFGT fueled with solid biomass is presented. • Detailed submodels for the HTHE and the chemical reactions are incorporated. • An arbitrary number of compression and expansion stages is considered. • Model validation leads to good agreement with experimental results. • A layout with two-stage compression leads to good efficiencies and power output. - Abstract: A thermodynamic model for a realistic Brayton cycle, working as an externally fired gas turbine fueled with biomass is presented. The use of an external combustion chamber, allows to burn dirty fuels to preheat pure air, which is the working fluid for the turbine. It also avoids direct contact of ashes with the turbine blades, resulting in a higher life cycle for the turbine. The model incorporates a high temperature heat exchanger and an arbitrary number of turbines and compressors, with the corresponding number of intercoolers and reheaters. It considers irreversibilities such as non-isentropic compressions and expansions, and pressure losses in heat input and release. The composition and temperature of the combustion gases, as well as the variable flow rate of air and combustion gases, are calculated for specific biomasses. The numerical model for a single stage configuration has been validated by comparing its predictions with the data sheets of two commercial turbines. Results are in good agreement. Curves on the dependence of thermal efficiency and power output with the overall pressure ratio will be shown for several plant configurations with variable number of compression/expansion stages. Also the influence of different types of biomasses and their moisture will be analyzed on parameters such as fuel consumption and exhaust gases temperature. For a single step plant layout fueled with eucalyptus wood an efficiency of 23% is predicted, whereas for a configuration with two compressors and one turbine efficiency increases up to 25%. But it is remarkable

  9. Direct cycle type nuclear power plant

    International Nuclear Information System (INIS)

    Tagawa, Hisato; Ibe, Hidefumi.

    1990-01-01

    In a direct cycle type nuclear power plant such as BWR type reactor, since oxygen atoms in reactor water are actuvated by neutron irradiation in the reactor core, carry over of the thus formed radioactive nitrogen atoms causes increase in the dosage in a turbine system. Since 16 N accompanies in the main steams in the chemical form of 16 NO, it can not effectively be removed in a nitrogen removing device. In view of the above, hydrogen atom concentration is reduced by adding metals having high reaction with hydrogen atoms, for example, silver ions, chromium ions, or ruthenium ions are added to reactor water. Then, equilibrium concentration of 16 NO in water is reduced by suppressing the reaction: 16 NO 2 + H → 16 NO + OH. (T.M.)

  10. Thermodynamics of the CO2–Absorption/Desorption Section in the Integrated Gasifying Combined cycle — II. Analysis

    Directory of Open Access Journals (Sweden)

    Jaroslav KOZACZKA

    2012-06-01

    Full Text Available The thermodynamic analysis of the absorption/desorption section of the ICGC–cycle has been presented using the Second Law with special emphasis on the thermodynamic effectivity concept and usability for complex systems investigations. Essential problems have been discussed based on the classical bibliographical items on the subject. Numerical calculations have been accomplished using results obtained in the first part, which contained absorption and desorption modeling approach oriented onto thermodynamic analyzes. Additionally the special properties of dilute solutions, especially the CO2/water system, have been presented and the problem of the solute chemical concentration exergy change suggested.

  11. Combined heat and power considered as a virtual steam cycle heat pump

    International Nuclear Information System (INIS)

    Lowe, Robert

    2011-01-01

    The first aim of this paper is to shed light on the thermodynamic reasons for the practical pursuit of low temperature operation by engineers involved in the design and the operation of combined heat and power (CHP) and district heating (DH) systems. The paper shows that the steam cycle of a combined heat and power generator is thermodynamically equivalent to a conventional steam cycle generator plus an additional virtual steam cycle heat pump. This apparently novel conceptualisation leads directly to (i) the observed sensitivity of coefficient of performance of CHP to supply and return temperatures in associated DH systems, and (ii) the conclusion that the performance of CHP will tend to be significantly higher than real heat pumps operating at similar temperatures. The second aim, which is pursued more qualitatively, is to show that the thermodynamic performance advantages of CHP are consistent with the goal of deep, long-term decarbonisation of industrialised economies. As an example, estimates are presented, which suggest that CHP based on combined-cycle gas turbines with carbon capture and storage has the potential to reduce the carbon intensity of delivered heat by a factor of ∼30, compared with a base case of natural gas-fired condensing boilers. - Highlights: → Large-scale CHP systems are thermodynamically equivalent to virtual steam cycle heat pumps. → COPs of such virtual heat pumps are necessarily better than the Carnot limit for real heat pumps. → COPs can approach 9 for plant matched to district heating systems with flow temperatures of 90 deg. C. → CHP combined with CCGT and CCS can reduce the carbon intensity of delivered heat ∼30-fold.

  12. Thermodynamic analysis of a gas turbine cycle equipped with a non-ideal adiabatic model for a double acting Stirling engine

    International Nuclear Information System (INIS)

    Korlu, Mahmood; Pirkandi, Jamasb; Maroufi, Arman

    2017-01-01

    Highlights: • A gas turbine cycle equipped with a double acting Stirling engine is proposed. • The hybrid cycle effects, efficiency and power outputs are investigated. • The energy dissipation, the net enthalpy loss and wall heat leakage are considered. • The hybrid cycle improves the efficiency from 23.6 to 38.8%. - Abstract: The aim of this study is to investigate the thermodynamic performance of a gas turbine cycle equipped with a double acting Stirling engine. A portion of gas turbine exhaust gases are allocated to providing the heat required for the Stirling engine. Employing this hybrid cycle improves gas turbine performance and power generation. The double acting Stirling engine is used in this study and the non-ideal adiabatic model is used to numerical solution. The regenerator’s net enthalpy loss, the regenerator’s wall heat leakage, the energy dissipation caused by pressure drops in heat exchangers and regenerator are the losses that were taken into account for the Stirling engine. The hybrid cycle, gas turbine governing equations and Stirling engine analyses are carried out using the Matlab software. The pressure ratio of the compressor, the inlet temperature of turbine, the porosity, length and diameter of the regenerator were chosen as essential parameters in this article. Also the hybrid cycle effects, efficiency and power outputs are investigated. The results show that the hybrid gas turbine and Stirling engine improves the efficiency from 23.6 to 38.8%.

  13. Thermodynamic assessment of IGCC power plants with hot fuel gas desulfurization

    International Nuclear Information System (INIS)

    Giuffrida, Antonio; Romano, Matteo C.; Lozza, Giovanni G.

    2010-01-01

    In IGCC power plants, hot gas desulfurization (HGD) represents an attractive solution to simplify syngas treatments and to improve the efficiency, potentially reducing the final cost of electricity. In the present study, the various consequences of the introduction of a HGD station in the power plant are discussed and evaluated, in comparison with conventional near-ambient temperature clean-up. Attention is paid to the potential improvements of the overall energy balance of the complete power station, along with the requirements of the sorbent regeneration process, to the influence of the desulfurization temperature and to the different solutions needed to control the NO x emissions (altered by the presence of HGD). The net performance of complete IGCC power plants (with HGD or with conventional desulfurization) were predicted, with reference to status-of-the-art solutions based on an entrained flow, dry-feed, oxygen-blown gasifier and on an advanced, FB-class combined cycle. The net efficiency experiences about 2.5% point improvement with HGD, even if a small reduction in the power output was predicted, when using the same combustion turbine. An exhaustive sensitivity analysis was carried out to evaluate the effects of different working conditions at the HGD station, e.g. desulfurization temperature and oxygen content in the gaseous stream for sorbent regeneration. According to the obtained results, these parameters have a weak influence on the efficiency. In particular, a very elevated desulfurization temperature (above 400-500 o C) does not provide decisive thermodynamic advantages. Therefore, the HGD unit optimization can be driven by technical and economical aspects and by emission abatement requirements. For instance, utilization of nitrogen for HGD sorbent regeneration (rather than for syngas dilution) and higher fuel temperature may improve the NO formation. Hence, different strategies to achieve acceptable NO x emissions (e.g. steam dilution) and their

  14. Analysis of thermodynamics of two-fuel power unit integrated with a carbon dioxide separation plant

    Directory of Open Access Journals (Sweden)

    Kotowicz Janusz

    2014-12-01

    Full Text Available The article presents the results of thermodynamic analysis of the supercritical coal-fired power plant with gross electrical output of 900 MW and a pulverized coal boiler. This unit is integrated with the absorption-based CO2 separation installation. The heat required for carrying out the desorption process, is supplied by the system with the gas turbine. Analyses were performed for two variants of the system. In the first case, in addition to the gas turbine there is an evaporator powered by exhaust gases from the gas turbine expander. The second expanded variant assumes the application of gas turbine combined cycle with heat recovery steam generator and backpressure steam turbine. The way of determining the efficiency of electricity generation and other defined indicators to assess the energy performance of the test block was showed. The size of the gas turbine system was chosen because of the need for heat for the desorption unit, taking the value of the heat demand 4 MJ/kg CO2. The analysis results obtained for the both variants of the installation with integrated CO2 separation plant were compared with the results of the analysis of the block where the separation is not conducted.

  15. Thermodynamic analysis of diesel engine coupled with ORC and absorption refrigeration cycle

    International Nuclear Information System (INIS)

    Salek, Farhad; Moghaddam, Alireza Naghavi; Naserian, Mohammad Mahdi

    2017-01-01

    Highlights: • Coupling ORC and Ammonia absorption cycles with diesel engine to recover energy. • By using designed bottoming system, recovered diesel engine energy is about 10%. • By using designed bottoming system, engine efficiency will grow about 4.65%. - Abstract: In this paper, Rankine cycle and Ammonia absorption cycle are coupled with Diesel engine to recover the energy of exhaust gases. The novelty of this paper is the use of ammonia absorption refrigeration cycle bottoming Rankine cycle which coupled with diesel engine to produce more power. Bottoming system converts engine exhaust thermal energy to cooling and mechanical energy. Energy transfer process has been done by two shell and tube heat exchangers. Simulation processes have been done by programming mathematic models of cycles in EES Program. Based on results, recovered energy varies with diesel engine load. For the particular load case of current research, the use of two heat exchangers causes 0.5% decrement of engine mechanical power. However, the recovered energy is about 10% of engine mechanical power.

  16. Politics of nuclear power and fuel cycle

    International Nuclear Information System (INIS)

    Uddin, R.

    2007-01-01

    -is likely to remain evolving depending on regional and global affairs. Opposition or support for nuclear technology is also likely to be a function of regional and global politics. In response to such pressures, IAEA is organizing a workshop of 140 countries to discuss proposals to guarantee countries' supply of nuclear fuel (September 19-21-, 2006; Vienna). Premise and Question: A single nuclear power plant in a country may be good for the prestige of the country, but such units are unlikely to make a major impact on the energy scene. Hence, in order for nuclear power to play a significant role, countries that decide to 'go nuclear,' would most likely want to diversify a significant fraction of their electricity generating capacity (and possibly heating and, in the future, hydrogen production) to nuclear, possibly requiring at least few and possibly many nuclear power plants. In order to proceed with the nuclear option, these countries would expect a certain level of long term assurance on the fuel supply. What is the kind of options that would satisfy the needs of these countries and at the same time addressing the non-proliferation concerns? Options: The options available to countries for their nuclear program can be categorized as follows. A. Fully indigenous program with complete development of power plants and fuel cycle. B. Fully or partly indigenous program for power plant development; while depending on international consortium for fuel supply and waste treatment. C. Rely on international consortia to build and operate all aspects of nuclear power plants (with local manpower). Others: A total of around fifty to seventy five countries are likely to be interested in nuclear power in the next fifty years. These can be divided in to the three groups (A-C) given above. It is likely that, with time, there will be some expectation to move to higher levels (C to B and B to A). Countries already in group A and those willing to start in group C do not pose an issue. It is

  17. Parametrized overview of CO_2 power cycles for different operation conditions and configurations – An absolute and relative performance analysis

    International Nuclear Information System (INIS)

    Cardemil, José M.; Silva, Alexandre K. da

    2016-01-01

    Highlights: • Thermodynamic modeling of CO_2-based power cycles. • A multi-parameter analysis for different cycle configurations. • Performance comparison between CO_2 and four other fluids. • Detailed discussion considering optimized operational parameters (i.e., pressure, HX size). • Overview of the technical applicability of the CO_2. - Abstract: This thermodynamically based study focuses on the thermal performance of power cycles using CO_2 as the working fluid. The work considers numerous aspects that can influence the cycle's performance, such as the type of cycle (i.e., Rankine or Brayton), its configuration (i.e., with and without a recuperator), and different operational conditions (i.e., heat source temperature and the upper and lower operating pressures of the CO_2). To account for all possible scenarios, a thermodynamic routine was especially implemented and linked to a library that contained all the thermodynamics properties of CO_2. The results are mostly presented in terms of the absolute and relative 1st and 2nd Law efficiencies of CO_2 as well as the cycle's scale, here represented by the global conductance (UA) of the heat exchangers used within the cycle. For the relative performance assessment, four other working fluids, commonly used in energy conversion cycles, were considered (i.e., ethane, toluene, D4 siloxane and water). As expected, the absolute performance results indicate a strong dependence of the cycle's efficiencies on the operational conditions. As for the relative performance, the results suggest that while the CO_2's 1st Law efficiency might be lower than other fluids, its exergetic efficiency can be significantly higher. Furthermore, the calculations also indicate that the CO_2's needed global conductance is potentially lower than competing fluids (e.g., toluene) for certain operational conditions, which suggests that CO_2-based power plants can be more compact, since they might require smaller heat exchangers to produce

  18. Effects of thermal cycling on aluminum metallization of power diodes

    DEFF Research Database (Denmark)

    Brincker, Mads; Pedersen, Kristian Bonderup; Kristensen, Peter Kjær

    2015-01-01

    Reconstruction of aluminum metallization on top of power electronic chips is a well-known wear out phenomenon under power cycling conditions. However, the origins of reconstruction are still under discussion. In the current study, a method for carrying out passive thermal cycling of power diodes...

  19. Thermodynamic, economic and thermo-economic optimization of a new proposed organic Rankine cycle for energy production from geothermal resources

    International Nuclear Information System (INIS)

    Kazemi, Neda; Samadi, Fereshteh

    2016-01-01

    Highlights: • A new cycle was designed to improve basic organic Rankine cycle performance. • Peng Robinson equation of state was used to obtain properties of working fluids. • Operating parameters were optimized with three different objective functions. • Efficiency of new organic Rankine cycle is higher than other considered cycles. • Return on investment of new cycle for Iran is more than France and America. - Abstract: The main goal of this study is to propose and investigate a new organic Rankine cycle based on three considered configurations: basic organic Rankine cycle, regenerative organic Rankine cycle and two-stage evaporator organic Rankine cycle in order to increase electricity generation from geothermal sources. To analyze the considered cycles’ performance, thermodynamic (energy and exergy based on the first and second laws of thermodynamics) and economic (specific investment cost) models are investigated. Also, a comparison of cycles modeling results is carried out in optimum conditions according to different optimization which consist thermodynamic, economic and thermo-economic objective functions for maximizing exergy efficiency, minimizing specific investment cost and applying a multi-objective function in order to maximize exergy efficiency and minimize specific investment cost, respectively. Optimized operating parameters of cycles include evaporators and regenerative temperatures, pinch point temperature difference of evaporators and degree of superheat. Furthermore, Peng Robinson equation of state is used to obtain thermodynamic properties of isobutane and R123 which are selected as dry and isentropic working fluids, respectively. The results of optimization indicate that, thermal and exergy efficiencies increase and exergy destruction decrease especially in evaporators for both working fluids in new proposed organic Rankine cycle compared to the basic organic Rankine cycle. Moreover, the amount of specific investment cost in new

  20. Optimizing design of converters using power cycling lifetime models

    DEFF Research Database (Denmark)

    Nielsen, Rasmus Ørndrup; Munk-Nielsen, Stig

    2015-01-01

    Converter power cycling lifetime depends heavily on converter operation point. A lifetime model of a single power module switched mode power supply with wide input voltage range is shown. A lifetime model is created using a power loss model, a thermal model and a model for power cycling capability...... with a given mission profile. A method to improve the expected lifetime of the converter is presented, taking into account switching frequency, input voltage and transformer turns ratio....

  1. Thermodynamic analysis on theoretical models of cycle combined heat exchange process: The reversible heat exchange process

    International Nuclear Information System (INIS)

    Zhang, Chenghu; Li, Yaping

    2017-01-01

    Concept of reversible heat exchange process as the theoretical model of the cycle combined heat exchanger could be useful to determine thermodynamics characteristics and the limitation values in the isolated heat exchange system. In this study, the classification of the reversible heat exchange processes is presented, and with the numerical method, medium temperature variation tendency and the useful work production and usage in the whole process are investigated by the construction and solution of the mathematical descriptions. Various values of medium inlet temperatures and heat capacity ratio are considered to analyze the effects of process parameters on the outlet temperature lift/drop. The maximum process work transferred from the Carnot cycle region to the reverse cycle region is also researched. Moreover, influence of the separating point between different sub-processes on temperature variation profile and the process work production are analyzed. In addition, the heat-exchange-enhancement-factor is defined to study the enhancement effect of the application of the idealized process in the isolated heat exchange system, and the variation degree of this factor with process parameters change is obtained. The research results of this paper can be a theoretical guidance to construct the cycle combined heat exchange process in the practical system. - Highlights: • A theoretical model of Cycle combined heat exchange process is proposed. • The classification of reversible heat exchange process are presented. • Effects of Inlet temperatures and heat capacity ratio on process are analyzed. • Process work transmission through the whole process is studied. • Heat-exchange-enhancement-factor can be a criteria to express the application effect of the idealized process.

  2. Thermodynamic analysis of turbine blade cooling on the performance of gas turbine cycle

    International Nuclear Information System (INIS)

    Sarabchi, K.; Shokri, M.

    2002-01-01

    Turbine inlet temperature strongly affects gas turbine performance. Today blade cooling technologies facilitate the use of higher inlet temperatures. Of course blade cooling causes some thermodynamic penalties that destroys to some extent the positive effect of higher inlet temperatures. This research aims to model and evaluate the performance of gas turbine cycle with air cooled turbine. In this study internal and transpiration cooling methods has been investigated and the penalties as the result of gas flow friction, cooling air throttling, mixing of cooling air flow with hot gas flow, and irreversible heat transfer have been considered. In addition, it is attempted to consider any factor influencing actual conditions of system in the analysis. It is concluded that penalties due to blade cooling decrease as permissible temperature of the blade surface increases. Also it is observed that transpiration method leads to better performance of gas turbine comparing to internal cooling method

  3. Thermodynamic analysis of engineering solutions aimed at raising the efficiency of integrated gasification combined cycle

    Science.gov (United States)

    Gordeev, S. I.; Bogatova, T. F.; Ryzhkov, A. F.

    2017-11-01

    Raising the efficiency and environmental friendliness of electric power generation from coal is the aim of numerous research groups today. The traditional approach based on the steam power cycle has reached its efficiency limit, prompted by materials development and maneuverability performance. The rival approach based on the combined cycle is also drawing nearer to its efficiency limit. However, there is a reserve for efficiency increase of the integrated gasification combined cycle, which has the energy efficiency at the level of modern steam-turbine power units. The limit of increase in efficiency is the efficiency of NGCC. One of the main problems of the IGCC is higher costs of receiving and preparing fuel gas for GTU. It would be reasonable to decrease the necessary amount of fuel gas in the power unit to minimize the costs. The effect can be reached by raising of the heat value of fuel gas, its heat content and the heat content of cycle air. On the example of the process flowsheet of the IGCC with a power of 500 MW, running on Kuznetsk bituminous coal, by means of software Thermoflex, the influence of the developed technical solutions on the efficiency of the power plant is considered. It is received that rise in steam-air blast temperature to 900°C leads to an increase in conversion efficiency up to 84.2%. An increase in temperature levels of fuel gas clean-up to 900°C leads to an increase in the IGCC efficiency gross/net by 3.42%. Cycle air heating reduces the need for fuel gas by 40% and raises the IGCC efficiency gross/net by 0.85-1.22%. The offered solutions for IGCC allow to exceed net efficiency of analogous plants by 1.8-2.3%.

  4. Development of a novel rotary desiccant cooling cycle with isothermal dehumidification and regenerative evaporative cooling using thermodynamic analysis method

    International Nuclear Information System (INIS)

    La, D.; Li, Y.; Dai, Y.J.; Ge, T.S.; Wang, R.Z.

    2012-01-01

    A novel rotary desiccant cooling cycle is proposed and studied using thermodynamic analysis method. The proposed cycle integrates the technologies of isothermal dehumidification and regenerative evaporative cooling, which are beneficial for irreversibility reduction. Thermodynamic investigation on the basic rotary desiccant cooling cycle shows that the exergy efficiency of the basic cycle is only 8.6%. The processes of desiccant dehumidification and evaporative cooling, which are essentially the basis for rotary desiccant cooling, affect the exergy performance of the cycle greatly and account for about one third of the total exergy destruction. The proposed cycle has potential to improve rotary desiccant cooling technology. It is advantageous in terms of both heat source utilization rate and space cooling capacity. The exergy efficiency of the new cycle is enhanced significantly to 29.1%, which is about three times that of the ventilation cycle, and 60% higher than that of the two-stage rotary desiccant cooling cycle. Furthermore, the regeneration temperature is reduced from 80 °C to about 60 °C. The corresponding specific exergy of the supply air is increased by nearly 30% when compared with the conventional cycles. -- Highlights: ► A novel rotary desiccant cooling cycle is developed using thermodynamic analysis method. ► Isothermal dehumidification and regenerative evaporative cooling have been integrated. ► The cycle is advantageous in terms of both heat source utilization rate and space cooling capacity. ► Cascaded energy utilization is beneficial for cycle performance improvement. ► Upper limits, which will be helpful to practical design and optimization, are obtained.

  5. Thermodynamic evaluation of supercritical oxy-type power plant with high-temperature three-end membrane for air separation

    Directory of Open Access Journals (Sweden)

    Kotowicz Janusz

    2014-09-01

    Full Text Available Among the technologies which allow to reduce greenhouse gas emissions, mainly of carbon dioxide, special attention deserves the idea of ‘zero-emission’ technology based on boilers working in oxy-combustion technology. In the paper a thermodynamic analysis of supercritical power plant fed by lignite was made. Power plant consists of: 600 MW steam power unit with live steam parameters of 650 °C/30 MPa and reheated steam parameters of 670 °C/6 MPa; circulating fluidized bed boiler working in oxy-combustion technology; air separation unit and installation of the carbon dioxide compression. Air separation unit is based on high temperature membrane working in three-end technology. Models of steam cycle, circulation fluidized bed boiler, air separation unit and carbon capture installation were made using commercial software. After integration of these models the net electricity generation efficiency as a function of the degree of oxygen recovery in high temperature membrane was analyzed.

  6. Performance of a Kilowatt-Class Stirling Power Conversion System in a Thermodynamically-Coupled Configuration

    Science.gov (United States)

    Geng, S. M.; Briggs, M. H.; Hervol, D. S.

    A pair of 1kWe free-piston Stirling power convertors has been modified into a thermodynamically coupled configuration, and performance map testing has been completed. This is the same configuration planned for the full-scale 12 kWe power conversion unit (PCU) that will be used in the Fission Power System Technology Demonstration Unit (TDU). The 1-kWe convertors were operated over a range of conditions to evaluate the effects of thermodynamic coupling on convertor performance and to identify any possible control challenges. The thermodynamically coupled convertor showed no measurable difference in performance from the baseline data collected when the engines were separate and no major control issues were encountered during operation. The results of this test are guiding controller development and instrumentation selection for the TDU.

  7. Thermodynamic analysis and multi-objective optimization of various ORC (organic Rankine cycle) configurations using zeotropic mixtures

    International Nuclear Information System (INIS)

    Sadeghi, Mohsen; Nemati, Arash; Ghavimi, Alireza; Yari, Mortaza

    2016-01-01

    In this paper, the performance of the ORC (organic Rankine cycle) powered by geothermal water, in three different configurations, including the simple ORC, PTORC (parallel two-stage ORC) and STORC (series two-stage ORC), using zeotrpoic working fluids is investigated from the viewpoints of the energy and exergy. In addition, considering the net power output and TSP (turbine size parameter) as the two objective functions, the multi-objective optimization with the aim of maximizing the first function and minimizing the second one, is performed to determine the optimal values of decision variables including evaporators 1 and 2 pressure, the pinch point temperature difference and the superheating degree. The results show that using zeotropic mixtures as the working fluid instead of a pure fluid such as R245fa, leads to 27.76%, 24.98% and 24.79% improvement in power generation in the simple ORC, PTORC and STORC, respectively and also lower values of TSP. Moreover, it is observed that STORC has the highest amount of net power output and R407A can be selected as the most appropriate working fluid. The optimization results demonstrate that at the final optimum point achieved by Pareto frontier, the values of the objective functions are gained 877 kW and 0.08218 m, respectively. - Highlights: • Three different configurations of ORC powered by geothermal water are analyzed. • The thermodynamic performance of these systems using zeotrpoic mixtures is investigated. • Multi-objective optimization is performed to obtain optimum performance. • The Pareto-frontier is used to automatically select the most promising solutions.

  8. Performance analysis and comparison of an Atkinson cycle coupled to variable temperature heat reservoirs under maximum power and maximum power density conditions

    International Nuclear Information System (INIS)

    Wang, P.-Y.; Hou, S.-S.

    2005-01-01

    In this paper, performance analysis and comparison based on the maximum power and maximum power density conditions have been conducted for an Atkinson cycle coupled to variable temperature heat reservoirs. The Atkinson cycle is internally reversible but externally irreversible, since there is external irreversibility of heat transfer during the processes of constant volume heat addition and constant pressure heat rejection. This study is based purely on classical thermodynamic analysis methodology. It should be especially emphasized that all the results and conclusions are based on classical thermodynamics. The power density, defined as the ratio of power output to maximum specific volume in the cycle, is taken as the optimization objective because it considers the effects of engine size as related to investment cost. The results show that an engine design based on maximum power density with constant effectiveness of the hot and cold side heat exchangers or constant inlet temperature ratio of the heat reservoirs will have smaller size but higher efficiency, compression ratio, expansion ratio and maximum temperature than one based on maximum power. From the view points of engine size and thermal efficiency, an engine design based on maximum power density is better than one based on maximum power conditions. However, due to the higher compression ratio and maximum temperature in the cycle, an engine design based on maximum power density conditions requires tougher materials for engine construction than one based on maximum power conditions

  9. Multi-objective thermodynamic optimization of an irreversible regenerative Brayton cycle using evolutionary algorithm and decision making

    OpenAIRE

    Rajesh Kumar; S.C. Kaushik; Raj Kumar; Ranjana Hans

    2016-01-01

    Brayton heat engine model is developed in MATLAB simulink environment and thermodynamic optimization based on finite time thermodynamic analysis along with multiple criteria is implemented. The proposed work investigates optimal values of various decision variables that simultaneously optimize power output, thermal efficiency and ecological function using evolutionary algorithm based on NSGA-II. Pareto optimal frontier between triple and dual objectives is obtained and best optimal value is s...

  10. Thermodynamic and economic analysis of a partially-underground tower-type boiler design for advanced double reheat power plants

    International Nuclear Information System (INIS)

    Xu, Gang; Xu, Cheng; Yang, Yongping; Fang, Yaxiong; Zhou, Luyao; Yang, Zhiping

    2015-01-01

    An increasing number of tower-type boilers have been selected for advanced double reheat power plants, due to the uniform flue gas profile and the smooth steam temperature increase. The tall height and long steam pipelines lengths will however, result in dramatic increases in the difficulty of construction, as well as increased power plant investment cost. Given these factors, a novel partially-underground tower-type boiler design has been proposed in this study, which has nearly half of the boiler embedded underground, thereby significantly reducing the boiler height and steam pipeline lengths. Thermodynamic and economic analyses were quantitatively conducted on a 1000 MW advanced double reheat steam cycle. Results showed that compared to the reference power plant, the power plant with the proposed tower-type boiler design could reduce the net heat rate by 18.3 kJ/kWh and could reduce the cost of electricity (COE) by $0.60/MWh. The study also investigated the effects of price fluctuations on the cost-effectiveness of the reference power plant, for both the conventional and the proposed tower-type boilers designs, and found that the double reheat power plant with the proposed tower-type boiler design would be even more competitive and price-effective when the coal price and the investment costs increase. The research of this paper may provide a promising tower-type boiler design for advanced double reheat power plants with lower construction complexity and better cost-effectiveness. - Highlights: • A partially-underground tower-type boiler in double reheat power plants is proposed. for double reheat power plants is proposed. • Thermodynamic and economic analyses are quantitatively conducted. • Better energetic efficiency and greater economic benefits are achieved. • The impacts of price fluctuations on the economic feasibility are discussed

  11. Thermodynamic analysis of single-stage and multi-stage adsorption refrigeration cycles with activated carbon–ammonia working pair

    International Nuclear Information System (INIS)

    Xu, S.Z.; Wang, L.W.; Wang, R.Z.

    2016-01-01

    Highlights: • Activated carbon–ammonia multi-stage adsorption refrigerator was analyzed. • COP, exergetic efficiency and entropy production of cycles were calculated. • Single-stage cycle usually has the advantages of simple structure and high COP. • Multi-stage cycles adapt to critical conditions better than single-stage cycle. • Boundary conditions for choosing optimal cycle were summarized as tables. - Abstract: Activated carbon–ammonia multi-stage adsorption refrigeration cycle was analyzed in this article, which realized deep-freezing for evaporating temperature under −18 °C with heating source temperature much lower than 100 °C. Cycle mathematical models for single, two and three-stage cycles were established on the basis of thorough thermodynamic analysis. According to simulation results of thermodynamic evaluation indicators such as COP (coefficient of performance), exergetic efficiency and cycle entropy production, multi-stage cycle adapts to high condensing temperature, low evaporating temperature and low heating source temperature well. Proposed cycle with selected working pair can theoretically work under very severe conditions, such as −25 °C evaporating temperature, 40 °C condensing temperature, and 70 °C heating source temperature, but under these working conditions it has the drawback of low cycle adsorption quantity. It was found that both COP and exergetic efficiency are of great reference value in the choice of cycle, whereas entropy production is not so useful for cycle stage selection. Finally, the application boundary conditions of single-stage, two-stage, and three-stage cycles were summarized as tables according to the simulation results, which provides reference for choosing optimal cycle under different conditions.

  12. Combined cycle power plants: technological prospects for improving the efficiency

    International Nuclear Information System (INIS)

    Lauri, R.

    2009-01-01

    The combined cycle power plants characteristics are better than one course open to a closed loop presenting an electrical efficiency close to 60% do not reach for gas turbine engines for power plants and conventional steam engines. [it

  13. Organic Rankine cycle for power recovery of exhaust flue gas

    International Nuclear Information System (INIS)

    Guo, Cong; Du, Xiaoze; Yang, Lijun; Yang, Yongping

    2015-01-01

    To study the effects of different working fluids on the performance of organic Rankine cycle (ORC), three working fluids, a mixture that matches with heat source, a mixture that matches with heat sink and a pure working fluid, are selected in this paper. Thermodynamic models were built in Matlab together with REFPROP, with which, the physical properties of the selected working fluids can be acquired. Heat source of the ORC system is the exhaust flue gas of boiler in a 240 MW pulverized coal-fired power plant. Some indicators such as thermal efficiency, inlet temperature of expander, superheat degree, mass flow, volumetric flow, and exergy destruction distribution, as well as the influence of recuperator are studied. The analytical results show that the mixture that matches with heat sink has the greatest efficiency and the mixture that matches with heat source has the lowest superheat degree. The rate of heat exchanged in recuperator to that in evaporator has a maximum value with evaporating pressure. There exists no optimal working fluid for all indicators (thermal efficiency, heat exchanger area, mass flow and volumetric flow etc.). An appropriate working fluid should be chosen by taking both investment cost and power generating benefits into account. The cost-benefit ratio of the proposed ORC plant was evaluated either. - Highlights: • Three types of working fluids are selected for ORC using exhaust flue gas. • The mixture that matches with heat sink has the greatest efficiency. • The mixture that matches with heat source has the lowest superheat degree. • There does not exist a working fluid that satisfies all the indicators

  14. A mixed integer linear programming model for integrating thermodynamic cycles for waste heat exploitation in process sites

    International Nuclear Information System (INIS)

    Oluleye, Gbemi; Smith, Robin

    2016-01-01

    Highlights: • MILP model developed for integration of waste heat recovery technologies in process sites. • Five thermodynamic cycles considered for exploitation of industrial waste heat. • Temperature and quantity of multiple waste heat sources considered. • Interactions with the site utility system considered. • Industrial case study presented to illustrate application of the proposed methodology. - Abstract: Thermodynamic cycles such as organic Rankine cycles, absorption chillers, absorption heat pumps, absorption heat transformers, and mechanical heat pumps are able to utilize wasted thermal energy in process sites for the generation of electrical power, chilling and heat at a higher temperature. In this work, a novel systematic framework is presented for optimal integration of these technologies in process sites. The framework is also used to assess the best design approach for integrating waste heat recovery technologies in process sites, i.e. stand-alone integration or a systems-oriented integration. The developed framework allows for: (1) selection of one or more waste heat sources (taking into account the temperatures and thermal energy content), (2) selection of one or more technology options and working fluids, (3) selection of end-uses of recovered energy, (4) exploitation of interactions with the existing site utility system and (5) the potential for heat recovery via heat exchange is also explored. The methodology is applied to an industrial case study. Results indicate a systems-oriented design approach reduces waste heat by 24%; fuel consumption by 54% and CO_2 emissions by 53% with a 2 year payback, and stand-alone design approach reduces waste heat by 12%; fuel consumption by 29% and CO_2 emissions by 20.5% with a 4 year payback. Therefore, benefits from waste heat utilization increase when interactions between the existing site utility system and the waste heat recovery technologies are explored simultaneously. The case study also shows

  15. Comparative thermodynamic performance of some Rankine/Brayton cycle configurations for a low-temperature energy application

    Science.gov (United States)

    Lansing, F. L.

    1977-01-01

    Various configurations combining solar-Rankine and fuel-Brayton cycles were analyzed in order to find the arrangement which has the highest thermal efficiency and the smallest fuel share. A numerical example is given to evaluate both the thermodynamic performance and the economic feasibility of each configuration. The solar-assisted regenerative Rankine cycle was found to be leading the candidates from both points of energy utilization and fuel conservation.

  16. Thermodynamic analysis of thermal efficiency and power of Minto engine

    International Nuclear Information System (INIS)

    He, Wei; Hou, Jingxin; Zhang, Yang; Ji, Jie

    2011-01-01

    Minto engine is a kind of liquid piston heat engine that operates on a small temperature gradient. But there is no power formula for it yet. And its thermal efficiency is low and formula sometimes is misused. In this paper, deriving the power formula and simplifying the thermal efficiency formula of Minto engine based on energy distribution analysis will be discussed. To improve the original Minto engine, a new design of improved Minto engine is proposed and thermal efficiency formula and power formula are also given. A computer program was developed to analyze thermal efficiency and power of original and improved Minto engines operating between low and high-temperature heat sources. The simulation results show that thermal efficiency of improved Minto engine can reach over 7% between 293.15 K and 353.15 K which is much higher than that of original one; the temperature difference between upper and lower containers is lower than half of that between low and high temperature of heat sources when the original Minto engines output the maximum power; on the contrary, it is higher in the improved Minto engines. -- Highlights: ► The thermal efficiency formula of Minto engine is simplified and the power formula is established. ► A high-powered design of improved Minto engine is proposed. ► A computer simulation program based on real operating environment is developed.

  17. Electrofishing power requirements in relation to duty cycle

    Science.gov (United States)

    Miranda, L.E.; Dolan, C.R.

    2004-01-01

    Under controlled laboratory conditions we measured the electrical peak power required to immobilize (i.e., narcotize or tetanize) fish of various species and sizes with duty cycles (i.e., percentage of time a field is energized) ranging from 1.5% to 100%. Electrofishing effectiveness was closely associated with duty cycle. Duty cycles of 10-50% required the least peak power to immobilize fish; peak power requirements increased gradually above 50% duty cycle and sharply below 10%. Small duty cycles can increase field strength by making possible higher instantaneous peak voltages that allow the threshold power needed to immobilize fish to radiate farther away from the electrodes. Therefore, operating within the 10-50% range of duty cycles would allow a larger radius of immobilization action than operating with higher duty cycles. This 10-50% range of duty cycles also coincided with some of the highest margins of difference between the electrical power required to narcotize and that required to tetanize fish. This observation is worthy of note because proper use of duty cycle could help reduce the mortality associated with tetany documented by some authors. Although electrofishing with intermediate duty cycles can potentially increase effectiveness of electrofishing, our results suggest that immobilization response is not fully accounted for by duty cycle because of a potential interaction between pulse frequency and duration that requires further investigation.

  18. Thermodynamic analysis of a dual loop heat recovery system with trilateral cycle applied to exhaust gases of internal combustion engine for propulsion of the 6800 TEU container ship

    International Nuclear Information System (INIS)

    Choi, Byung Chul; Kim, Young Min

    2013-01-01

    A dual loop waste heat recovery power generation system that comprises an upper trilateral cycle and a lower organic Rankine cycle, in which discharged exhaust gas heat is recovered and re-used for propulsion power, was theoretically applied to an internal combustion engine for propulsion in a 6800 TEU container ship. The thermodynamic properties of this exhaust gas heat recovery system, which vary depending on the boundary temperature between the upper and lower cycles, were also investigated. The results confirmed that this dual loop exhaust gas heat recovery power generation system exhibited a maximum net output of 2069.8 kW, and a maximum system efficiency of 10.93% according to the first law of thermodynamics and a maximum system exergy efficiency of 58.77% according to the second law of thermodynamics. In this case, the energy and exergy efficiencies of the dual loop system were larger than those of the single loop trilateral cycle. Further, in the upper trilateral cycle, the volumetric expansion ratio of the turbine could be considerably reduced to an adequate level to be employed in the practical system. When this dual loop exhaust gas heat recovery power generation system was applied to the main engine of the container ship, which was actually in operation, a 2.824% improvement in propulsion efficiency was confirmed in comparison to the case of a base engine. This improvement in propulsion efficiency resulted in about 6.06% reduction in the specific fuel oil consumption and specific CO 2 emissions of the main engine during actual operation. - Highlights: • WHRS was theoretically applied to exhaust gas of a main engine for ship propulsion. • A dual loop EG-WHRS using water and R1234yf as working fluids has been suggested. • Limitation of single loop trilateral cycle was improved by the dual loop system. • The propulsion efficiency of 2.824% was improved by the dual loop EG-WHRS. • This resulted in about 6.06% reduction in the SFOC and specific CO

  19. Thermodynamic performance simulation and concise formulas for triple-pressure reheat HRSG of gas–steam combined cycle under off-design condition

    International Nuclear Information System (INIS)

    Zhang, Guoqiang; Zheng, Jiongzhi; Yang, Yongping; Liu, Wenyi

    2016-01-01

    Highlights: • An off-design performance simulation of triple-pressure reheat HRSG is executed. • The bottoming cycle characteristics of energy transfer/conversion are analyzed. • Concise formulas for the off-design performance of bottoming cycle are proposed. • The accuracy of the formulas is verified under different load control strategies. • The errors of the formulas are generally within 1% at a load of 100–50%. - Abstract: Concise semi-theoretical, semi-empirical formulas are developed in this study to predict the off-design performance of the bottoming cycle of the gas–steam turbine combined cycle. The formulas merely refer to the key thermodynamic design parameters (full load parameters) of the bottoming cycle and off-design gas turbine exhaust temperature and flow, which are convenient in determining the overall performance of the bottoming cycle. First, a triple-pressure reheat heat recovery steam generator (HRSG) is modeled, and thermodynamic analysis is performed. Second, concise semi-theoretical, semi-empirical performance prediction formulas for the bottoming cycle are proposed through a comprehensive analysis of the heat transfer characteristics of the HRSG and the energy conversion characteristics of the steam turbine under the off-design condition. The concise formulas are found to be effective, i.e., fast, simple, and precise in obtaining the thermodynamic parameters for bottoming cycle efficiency, HRSG heat transfer capacity, HRSG efficiency, steam turbine power output, and steam turbine efficiency under the off-design condition. Accuracy is verified by comparing the concise formulas’ calculation results with the simulation results and practical operation data under different load control strategies. The calculation errors are within 1.5% (mainly less than 1% for both simulation and actual operation data) under combined cycle load (gas turbine load) ranging from 50% to 100%. However, accuracy declines sharply when the turbine

  20. An integrated solar thermal power system using intercooled gas turbine and Kalina cycle

    International Nuclear Information System (INIS)

    Peng, Shuo; Hong, Hui; Jin, Hongguang; Wang, Zhifeng

    2012-01-01

    A new solar tower thermal power system integrating the intercooled gas turbine top cycle and the Kalina bottoming cycle is proposed in the present paper. The thermodynamic performance of the proposed system is investigated, and the irreversibility of energy conversion is disclosed using the energy–utilization diagram method. On the top cycle of the proposed system, the compressed air after being intercooled is heated at 1000 °C or higher at the solar tower receiver and is used to drive the gas turbine to generate power. The ammonia–water mixture as the working substance of the bottom cycle recovers the waste heat from the gas turbine to generate power. A concise analytical formula of solar-to-electric efficiency of the proposed system is developed. As a result, the peak solar-to-electric efficiency of the proposed system is 27.5% at a gas turbine inlet temperature of 1000 °C under the designed solar direct normal irradiance of 800 W/m 2 . Compared with a conventional solar power tower plant, the proposed integrated system conserves approximately 69% of consumed water. The results obtained in the current study provide an approach to improve solar-to-electric efficiency and offer a potential to conserve water for solar thermal power plants in arid area. -- Highlights: ► An Integrated Solar Thermal Power System is modeled. ► A formula forecasting the thermodynamic performance is proposed. ► The irreversibility of energy conversion is disclosed using an energy utilization method. ► The effect of key operational parameters on thermal performance is examined.

  1. Microfabricated rankine cycle steam turbine for power generation and methods of making the same

    Science.gov (United States)

    Frechette, Luc (Inventor); Muller, Norbert (Inventor); Lee, Changgu (Inventor)

    2009-01-01

    In accordance with the present invention, an integrated micro steam turbine power plant on-a-chip has been provided. The integrated micro steam turbine power plant on-a-chip of the present invention comprises a miniature electric power generation system fabricated using silicon microfabrication technology and lithographic patterning. The present invention converts heat to electricity by implementing a thermodynamic power cycle on a chip. The steam turbine power plant on-a-chip generally comprises a turbine, a pump, an electric generator, an evaporator, and a condenser. The turbine is formed by a rotatable, disk-shaped rotor having a plurality of rotor blades disposed thereon and a plurality of stator blades. The plurality of stator blades are interdigitated with the plurality of rotor blades to form the turbine. The generator is driven by the turbine and converts mechanical energy into electrical energy.

  2. Hybrid solar central receiver for combined cycle power plant

    Science.gov (United States)

    Bharathan, Desikan; Bohn, Mark S.; Williams, Thomas A.

    1995-01-01

    A hybrid combined cycle power plant including a solar central receiver for receiving solar radiation and converting it to thermal energy. The power plant includes a molten salt heat transfer medium for transferring the thermal energy to an air heater. The air heater uses the thermal energy to preheat the air from the compressor of the gas cycle. The exhaust gases from the gas cycle are directed to a steam turbine for additional energy production.

  3. Thermodynamic Analysis of an Integrated Gasification Solid Oxide Fuel Cell Plant with a Kalina Cycle

    DEFF Research Database (Denmark)

    Pierobon, Leonardo; Rokni, Masoud

    2015-01-01

    % is achieved; plant size and nominal power are selected based on the required cultivation area. SOFC heat recovery with SKC is compared to a Steam Cycle (SC). Although ammonia-water more accurately fits the temperature profile of the off-gases, the presence of a Hybrid Recuperator enhances the available work......-treated fuel then enters the anode side of the SOFC. Complete fuel oxidation is ensured in a burner by off-gases exiting the SOFC stacks. Off-gases are utilized as heat source for a SKC where a mixture of ammonia and water is expanded in a turbine to produce additional electric power. Thus, a triple novel......A hybrid plant that consists of a gasification system, Solid Oxide Fuel Cells (SOFC) and a Simple Kalina Cycle (SKC) is investigated. Woodchips are introduced into a fixed bed gasification plant to produce syngas, which is then fed into an integrated SOFC-SKC plant to produce electricity. The pre...

  4. Continuity and boundary conditions in thermodynamics: From Carnot's efficiency to efficiencies at maximum power

    Science.gov (United States)

    Ouerdane, H.; Apertet, Y.; Goupil, C.; Lecoeur, Ph.

    2015-07-01

    Classical equilibrium thermodynamics is a theory of principles, which was built from empirical knowledge and debates on the nature and the use of heat as a means to produce motive power. By the beginning of the 20th century, the principles of thermodynamics were summarized into the so-called four laws, which were, as it turns out, definitive negative answers to the doomed quests for perpetual motion machines. As a matter of fact, one result of Sadi Carnot's work was precisely that the heat-to-work conversion process is fundamentally limited; as such, it is considered as a first version of the second law of thermodynamics. Although it was derived from Carnot's unrealistic model, the upper bound on the thermodynamic conversion efficiency, known as the Carnot efficiency, became a paradigm as the next target after the failure of the perpetual motion ideal. In the 1950's, Jacques Yvon published a conference paper containing the necessary ingredients for a new class of models, and even a formula, not so different from that of Carnot's efficiency, which later would become the new efficiency reference. Yvon's first analysis of a model of engine producing power, connected to heat source and sink through heat exchangers, went fairly unnoticed for twenty years, until Frank Curzon and Boye Ahlborn published their pedagogical paper about the effect of finite heat transfer on output power limitation and their derivation of the efficiency at maximum power, now mostly known as the Curzon-Ahlborn (CA) efficiency. The notion of finite rate explicitly introduced time in thermodynamics, and its significance cannot be overlooked as shown by the wealth of works devoted to what is now known as finite-time thermodynamics since the end of the 1970's. The favorable comparison of the CA efficiency to actual values led many to consider it as a universal upper bound for real heat engines, but things are not so straightforward that a simple formula may account for a variety of situations. The

  5. A combined power cycle utilizing low-temperature waste heat and LNG cold energy

    International Nuclear Information System (INIS)

    Shi Xiaojun; Che Defu

    2009-01-01

    This paper has proposed a combined power system, in which low-temperature waste heat can be efficiently recovered and cold energy of liquefied natural gas (LNG) can be fully utilized as well. This system consists of an ammonia-water mixture Rankine cycle and an LNG power generation cycle, and it is modelled by considering mass, energy and species balances for every component and thermodynamic analyses are conducted. The results show that the proposed combined cycle has good performance, with net electrical efficiency and exergy efficiency of 33% and 48%, respectively, for a typical operating condition. The power output is equal to 1.25 MWh per kg of ammonia-water mixture. About 0.2 MW of electrical power for operating sea water pumps can be saved. Parametric analyses are performed for the proposed combined cycle to evaluate the effects of key factors on the performance of the proposed combined cycle through simulation calculations. Results show that a maximum net electrical efficiency can be obtained as the inlet pressure of ammonia turbine increases and the peak value increases as the ammonia mass fraction increases. Exergy efficiency goes up with the increased ammonia turbine inlet pressure. With the ammonia mass fraction increases, the net electrical efficiency increases, whereas exergy efficiency decreases. For increasing LNG turbine inlet pressure or heat source temperature, there is also a peak of net electrical efficiency and exergy efficiency. With the increase of LNG gas turbine outlet pressure, exergy efficiency increases while net electrical efficiency drops

  6. On q-power cycles in cubic graphs

    DEFF Research Database (Denmark)

    Bensmail, Julien

    2017-01-01

    In the context of a conjecture of Erdos and Gyárfás, we consider, for any q ≥ 2, the existence of q-power cycles (i.e. with length a power of q) in cubic graphs. We exhibit constructions showing that, for every q ≥ 3, there exist arbitrarily large cubic graphs with no q-power cycles. Concerning...... the remaining case q = 2 (which corresponds to the conjecture of Erdos and Gyárfás), we show that there exist arbitrarily large cubic graphs whose only 2-power cycles have length 4 only, or 8 only....

  7. EXPERIMENTAL AND THEORETICAL INVESTIGATIONS OF NEW POWER CYCLES AND ADVANCED FALLING FILM HEAT EXCHANGERS; FINAL

    International Nuclear Information System (INIS)

    Arsalan Razani; Kwang J. Kim

    2001-01-01

    The final report for the DOE/UNM grant number DE-FG26-98FT40148 discusses the accomplishments of both the theoretical analysis of advanced power cycles and experimental investigation of advanced falling film heat exchangers. This final report also includes the progress report for the third year (period of October 1, 2000 to September 30, 2001). Four new cycles were studied and two cycles were analyzed in detail based on the second law of thermodynamics. The first cycle uses a triple combined cycle, which consists of a topping cycle (Brayton/gas), an intermediate cycle (Rankine/steam), and a bottoming cycle (Rankine/ammonia). This cycle can produce high efficiency and reduces the irreversibility of the Heat Recovery Steam Generator (HRSC) of conventional combined power cycles. The effect of important system parameters on the irreversibility distribution of all components in the cycle under reasonable practical constraints was evaluated. The second cycle is a combined cycle, which consists of a topping cycle (Brayton/gas) and a bottoming cycle (Rankine/ammonia) with integrated compressor inlet air cooling. This innovative cycle can produce high power and efficiency. This cycle is also analyzed and optimized based on the second the second law to obtain the irreversibility distribution of all components in the cycle. The results of the studies have been published in peer reviewed journals and ASME conference proceeding. Experimental investigation of advanced falling film heat exchangers was conducted to find effective additives for steam condensation. Four additives have been selected and tested in a horizontal tube steam condensation facility. It has been observed that heat transfer additives have been shown to be an effective way to increase the efficiency of conventional tube bundle condenser heat exchangers. This increased condensation rate is due to the creation of a disturbance in the liquid condensate surround the film. The heat transfer through such a film has

  8. Thermodynamic modelling and efficiency analysis of a class of real indirectly fired gas turbine cycles

    Directory of Open Access Journals (Sweden)

    Ma Zheshu

    2009-01-01

    Full Text Available Indirectly or externally-fired gas-turbines (IFGT or EFGT are novel technology under development for small and medium scale combined power and heat supplies in combination with micro gas turbine technologies mainly for the utilization of the waste heat from the turbine in a recuperative process and the possibility of burning biomass or 'dirty' fuel by employing a high temperature heat exchanger to avoid the combustion gases passing through the turbine. In this paper, by assuming that all fluid friction losses in the compressor and turbine are quantified by a corresponding isentropic efficiency and all global irreversibilities in the high temperature heat exchanger are taken into account by an effective efficiency, a one dimensional model including power output and cycle efficiency formulation is derived for a class of real IFGT cycles. To illustrate and analyze the effect of operational parameters on IFGT efficiency, detailed numerical analysis and figures are produced. The results summarized by figures show that IFGT cycles are most efficient under low compression ratio ranges (3.0-6.0 and fit for low power output circumstances integrating with micro gas turbine technology. The model derived can be used to analyze and forecast performance of real IFGT configurations.

  9. Changes of the thermodynamic parameters in failure conditions of the micro-CHP cycle

    Science.gov (United States)

    Matysko, Robert; Mikielewicz, Jarosław; Ihnatowicz, Eugeniusz

    2014-03-01

    The paper presents the calculations for the failure conditions of the ORC (organic Rankine cycle) cycle in the electrical power system. It analyses the possible reasons of breakdown, such as the electrical power loss or the automatic safety valve failure. The micro-CHP (combined heat and power) system should have maintenance-free configuration, which means that the user does not have to be acquainted with all the details of the ORC system operation. However, the system should always be equipped with the safety control systems allowing for the immediate turn off of the ORC cycle in case of any failure. In case of emergency, the control system should take over the safety tasks and protect the micro-CHP system from damaging. Although, the control systems are able to respond quickly to the CHP system equipped with the inertial systems, the negative effects of failure are unavoidable and always remain for some time. Moreover, the paper presents the results of calculations determining the inertia for the micro-CHP system of the circulating ORC pump, heat removal pump (cooling condenser) and the heat supply pump in failure conditions.

  10. Changes of the thermodynamic parameters in failure conditions of the micro-CHP cycle

    Directory of Open Access Journals (Sweden)

    Matysko Robert

    2014-03-01

    Full Text Available The paper presents the calculations for the failure conditions of the ORC (organic Rankine cycle cycle in the electrical power system. It analyses the possible reasons of breakdown, such as the electrical power loss or the automatic safety valve failure. The micro-CHP (combined heat and power system should have maintenance-free configuration, which means that the user does not have to be acquainted with all the details of the ORC system operation. However, the system should always be equipped with the safety control systems allowing for the immediate turn off of the ORC cycle in case of any failure. In case of emergency, the control system should take over the safety tasks and protect the micro-CHP system from damaging. Although, the control systems are able to respond quickly to the CHP system equipped with the inertial systems, the negative effects of failure are unavoidable and always remain for some time. Moreover, the paper presents the results of calculations determining the inertia for the micro-CHP system of the circulating ORC pump, heat removal pump (cooling condenser and the heat supply pump in failure conditions.

  11. Specification of life cycle assessment in nuclear power plants

    International Nuclear Information System (INIS)

    Abbaspour, M.; Kargari, N.; Mastouri, R.

    2008-01-01

    Life Cycle Assessment is an environmental management tool for assessing the environmental impacts of a product of a process. life cycle assessment involves the evaluation of environmental impacts through all stages of life cycle of a product or process. In other words life cycle assessment has a c radle to grave a pproach. Some results of life cycle assessment consist of pollution prevention, energy efficient system, material conservation, economic system and sustainable development. All power generation technologies affect the environment in one way or another. The main environmental impact does not always occur during operation of power plant. The life cycle assessment of nuclear power has entailed studying the entire fuel cycle from mine to deep repository, as well as the construction, operation and demolition of the power station. Nuclear power plays an important role in electricity production for several countries. even though the use of nuclear power remains controversial. But due to the shortage of fossil fuel energy resources many countries have started to try more alternation to their sources of energy production. A life cycle assessment could detect all environmental impacts of nuclear power from extracting resources, building facilities and transporting material through the final conversion to useful energy services

  12. Comparison of Optimal Thermodynamic Models of the Tricarboxylic Acid Cycle from Heterotrophs, Cyanobacteria, and Green Sulfur Bacteria.

    Science.gov (United States)

    Thomas, Dennis G; Jaramillo-Riveri, Sebastian; Baxter, Douglas J; Cannon, William R

    2014-12-26

    We have applied a new stochastic simulation approach to predict the metabolite levels, material flux, and thermodynamic profiles of the oxidative TCA cycles found in E. coli and Synechococcus sp. PCC 7002, and in the reductive TCA cycle typical of chemolithoautotrophs and phototrophic green sulfur bacteria such as Chlorobaculum tepidum. The simulation approach is based on modeling states using statistical thermodynamics and employs an assumption similar to that used in transition state theory. The ability to evaluate the thermodynamics of metabolic pathways allows one to understand the relationship between coupling of energy and material gradients in the environment and the self-organization of stable biological systems, and it is shown that each cycle operates in the direction expected due to its environmental niche. The simulations predict changes in metabolite levels and flux in response to changes in cofactor concentrations that would be hard to predict without an elaborate model based on the law of mass action. In fact, we show that a thermodynamically unfavorable reaction can still have flux in the forward direction when it is part of a reaction network. The ability to predict metabolite levels, energy flow, and material flux should be significant for understanding the dynamics of natural systems and for understanding principles for engineering organisms for production of specialty chemicals.

  13. Conceptual design of a thermo-electrical energy storage system based on heat integration of thermodynamic cycles – Part A: Methodology and base case

    International Nuclear Information System (INIS)

    Morandin, Matteo; Maréchal, François; Mercangöz, Mehmet; Buchter, Florian

    2012-01-01

    The interest in large scale electricity storage (ES) with discharging time longer than 1 h and nominal power greater than 1 MW, is increasing worldwide as the increasing share of renewable energy, typically solar and wind energy, imposes severe load management issues. Thermo-electrical energy storage (TEES) based on thermodynamic cycles is currently under investigation at ABB corporate research as an alternative solution to pump hydro and compressed air energy storage. TEES is based on the conversion of electricity into thermal energy during charge by means of a heat pump and on the conversion of thermal energy into electricity during discharge by means of a thermal engine. The synthesis and the thermodynamic optimization of a TEES system based on hot water, ice storage and transcritical CO 2 cycles, is discussed in two papers. In this first paper a methodology for the conceptual design of a TEES system based on the analysis of the thermal integration between charging and discharging cycles through Pinch Analysis tools is introduced. According to such methodology, the heat exchanger network and temperatures and volumes of storage tanks are not defined a priori but are determined after the cycle parameters are optimized. For this purpose a heuristic procedure based on the interpretation of the composite curves obtained by optimizing the thermal integration between the cycles was developed. Such heuristic rules were implemented in a code that allows finding automatically the complete system design for given values of the intensive parameters of the charging and discharging cycles only. A base case system configuration is introduced and the results of its thermodynamic optimization are discussed here. A maximum roundtrip efficiency of 60% was obtained for the base case configuration assuming turbomachinery and heat exchanger performances in line with indications from manufacturers. -- Highlights: ► Energy storage based on water, ice, and transcritical CO 2 cycles is

  14. Combined Turbine and Cycle Optimization for Organic Rankine Cycle Power Systems—Part A

    DEFF Research Database (Denmark)

    Meroni, Andrea; La Seta, Angelo; Andreasen, Jesper Graa

    2016-01-01

    Axial-flow turbines represent a well-established technology for a wide variety of power generation systems. Compactness, flexibility, reliability and high efficiency have been key factors for the extensive use of axial turbines in conventional power plants and, in the last decades, in organic...... Rankine cycle power systems. In this two-part paper, an overall cycle model and a model of an axial turbine were combined in order to provide a comprehensive preliminary design of the organic Rankine cycle unit, taking into account both cycle and turbine optimal designs. Part A presents the preliminary...

  15. Noncircular Chainrings Do Not Influence Maximum Cycling Power.

    Science.gov (United States)

    Leong, Chee-Hoi; Elmer, Steven J; Martin, James C

    2017-12-01

    Noncircular chainrings could increase cycling power by prolonging the powerful leg extension/flexion phases, and curtailing the low-power transition phases. We compared maximal cycling power-pedaling rate relationships, and joint-specific kinematics and powers across 3 chainring eccentricities (CON = 1.0; LOW ecc  = 1.13; HIGH ecc  = 1.24). Part I: Thirteen cyclists performed maximal inertial-load cycling under 3 chainring conditions. Maximum cycling power and optimal pedaling rate were determined. Part II: Ten cyclists performed maximal isokinetic cycling (120 rpm) under the same 3 chainring conditions. Pedal and joint-specific powers were determined using pedal forces and limb kinematics. Neither maximal cycling power nor optimal pedaling rate differed across chainring conditions (all p > .05). Peak ankle angular velocity for HIGH ecc was less than CON (p pedal system allowed cyclists to manipulate ankle angular velocity to maintain their preferred knee and hip actions, suggesting maximizing extension/flexion and minimizing transition phases may be counterproductive for maximal power.

  16. Thermodynamic Analysis of Simple Gas Turbine Cycle with Multiple Regression Modelling and Optimization

    Directory of Open Access Journals (Sweden)

    Abdul Ghafoor Memon

    2014-03-01

    Full Text Available In this study, thermodynamic and statistical analyses were performed on a gas turbine system, to assess the impact of some important operating parameters like CIT (Compressor Inlet Temperature, PR (Pressure Ratio and TIT (Turbine Inlet Temperature on its performance characteristics such as net power output, energy efficiency, exergy efficiency and fuel consumption. Each performance characteristic was enunciated as a function of operating parameters, followed by a parametric study and optimization. The results showed that the performance characteristics increase with an increase in the TIT and a decrease in the CIT, except fuel consumption which behaves oppositely. The net power output and efficiencies increase with the PR up to certain initial values and then start to decrease, whereas the fuel consumption always decreases with an increase in the PR. The results of exergy analysis showed the combustion chamber as a major contributor to the exergy destruction, followed by stack gas. Subsequently, multiple regression models were developed to correlate each of the response variables (performance characteristic with the predictor variables (operating parameters. The regression model equations showed a significant statistical relationship between the predictor and response variables.

  17. Thermodynamic analysis of an open cycle solid desiccant cooling system using Artificial Neural Network

    International Nuclear Information System (INIS)

    Koronaki, I.P.; Rogdakis, E.; Kakatsiou, T.

    2012-01-01

    Highlights: ► A neural network model based on experimental data was developed. ► Description of the experimental setup. ► Prediction of the state conditions of air at the process and regeneration stream. ► Sensitivity Analysis performed on these predicted results. ► Predicted output values in line with correlation model based on data from industry. - Abstract: This paper examines the performance of an installed open cycle air-conditioning system with a silica gel desiccant wheel which uses a conventional heat pump and heat exchangers for the improvement of the outlet air of the system. A neural network model based on the training of a black box model with experimental data was developed as a method based on experimental results predicting the state conditions of air at the process and regeneration stream. The model development was followed by a Sensitivity Analysis performed on these predicted results. The key parameters were the thermodynamic condition of process and regeneration air streams, the sensible heat factor of the room, and the mass air flow ratio of the regeneration and process streams. The results of this analysis revealed that all investigated parameters influenced the performance of the desiccant unit. Predicted output values of the proposed Neural Network Model for Desiccant Systems are in line with results from other correlation models based on the interpolation of experimental data obtained from industrial air conditioning installations.

  18. Nuclear power and the nuclear fuel cycle

    International Nuclear Information System (INIS)

    1988-06-01

    The percentage of electricity generated by nuclear energy in each of the 26 countries that operated nuclear power plants in 1987 is given. The current policy and programs of some of these countries is described. News concerning uranium mining, enrichment, reprocessing and waste management is also included. Data in the form of a generalized status summary for all power reactors (> 30 MWEN) prepared from the nuclear power reactor data files of ANSTO is shown

  19. Low CO2-emissions hybrid solar combined-cycle power system with methane membrane reforming

    International Nuclear Information System (INIS)

    Li, Yuanyuan; Zhang, Na; Cai, Ruixian

    2013-01-01

    Based on the principle of cascade utilization of multiple energy resources, a gas-steam combined cycle power system integrated with solar thermo-chemical fuel conversion and CO 2 capture has been proposed and analyzed. The collected solar heat at 550 °C drives the endothermic methane reforming and is converted to the produced syngas chemical exergy, and then released as high-temperature thermal energy via combustion for power generation, achieving its high-efficiency heat-power conversion. The reforming reaction is integrated with a hydrogen separation membrane, which continuously withdraws hydrogen from the reaction zone and enables nearly full methane conversion. The CO 2 enriched gas being concentrated in the retentate zone is collected and processed with pre-combustion decarbonization. The system is thermodynamically simulated using the ASPEN PLUS code. The results show that with 91% CO 2 captured, the specific CO 2 emission is 25 g/kWh. An exergy efficiency of 58% and thermal efficiency of 51.6% can be obtained. A fossil fuel saving ratio of 31.2% is achievable with a solar thermal share of 28.2%, and the net solar-to-electricity efficiency based on the gross solar heat incident on the collector is about 36.4% compared with the same gas-steam combined cycle system with an equal CO 2 removal ratio obtained by post-combustion decarbonization. - Highlights: ► A solar-assisted hybrid combined cycle power system has been proposed and analyzed. ► The system integrates power generation with solar-driven reforming and CO 2 capture. ► solar heat upgrading and high-efficiency heat-to-power conversion are achieved. ► membrane reforming enables high CH 4 conversion and pre-combustion CO 2 capture. ► The system thermodynamic performances have been investigated and compared

  20. 47 CFR 27.50 - Power limits and duty cycle.

    Science.gov (United States)

    2010-10-01

    ... MISCELLANEOUS WIRELESS COMMUNICATIONS SERVICES Technical Standards § 27.50 Power limits and duty cycle. (a) The.... In measuring transmissions in this band using an average power technique, the peak-to-average ratio (PAR) of the transmission may not exceed 13 dB. (6) Peak transmit power must be measured over any...

  1. Waste-to-energy advanced cycles and new design concepts for efficient power plants

    CERN Document Server

    Branchini, Lisa

    2015-01-01

    This book provides an overview of state-of-the-art technologies for energy conversion from waste, as well as a much-needed guide to new and advanced strategies to increase Waste-to-Energy (WTE) plant efficiency. Beginning with an overview of municipal solid waste production and disposal, basic concepts related to Waste-To-Energy conversion processes are described, highlighting the most relevant aspects impacting the thermodynamic efficiency of WTE power plants. The pervasive influences of main steam cycle parameters and plant configurations on WTE efficiency are detailed and quantified. Advanc

  2. Thermodynamic analysis of waste heat power generation system

    International Nuclear Information System (INIS)

    Guo, Jiangfeng; Xu, Mingtian; Cheng, Lin

    2010-01-01

    In the present work, a waste heat power generation system is analyzed based on the criteria with and without considering the heat/exergy loss to the environment. For the criteria without considering the heat/exergy loss to the environment, the first- and second-law efficiencies display different tendencies with the variations of some system parameters. When the heat/exergy loss to the environment is taken into consideration, the first and second law efficiencies display the same tendency. Thus, choosing the appropriate expressions for the performance criteria is crucial for the optimization design of the waste heat power generation system. It is found that there are two approaches to improving the system performance: one is to improve the heat/exergy input; the other is to enhance the heat-work conversion ability of the system. The former would deteriorate the environment if the heat-work conversion ability of the system remains unchanged; the latter could reduce the environmental impact but it's restricted by the heat/exergy input. Therefore, the optimal operation condition should be achieved at the trade-off between the heat/exergy input and the heat-work conversion ability of the system.

  3. Basic chemically recuperated gas turbines--power plant optimization and thermodynamics second law analysis

    International Nuclear Information System (INIS)

    Alves, Lourenco Gobira; Nebra, Silvia Azucena

    2004-01-01

    One of the proposals to increase the performance of the gas turbines is to improve chemical recuperated cycle. In this cycle, the heat in the turbine exhaust gases is used to heat and modify the chemical characteristics of the fuel. One mixture of natural gas and steam receives heat from the exhaust turbine gases; the mixture components react among themselves producing hot synthesis gas. In this work, an analysis and nonlinear optimization of the cycle were made in order to investigate the temperature and pressure influence on the global cycle performance. The chemical composition in the reformer was assumed according to chemical equilibrium equations, which presents good agreement with data from literature. The mixture of hot gases was treated like ideal gases. The maximum net profit was achieved and a thermodynamic second law analysis was made in order to detect the greatest sources of irreversibility

  4. Theoretical analysis of a combined power and ejector refrigeration cycle using zeotropic mixture

    International Nuclear Information System (INIS)

    Yang, Xingyang; Zhao, Li; Li, Hailong; Yu, Zhixin

    2015-01-01

    Highlights: • A combined power and refrigeration cycle using zeotropic mixture is analyzed. • The cycle performances with different mixture compositions are compared. • Both exergy and parametric analysis of the combined cycle are conducted. - Abstract: A theoretical study on a combined power and ejector refrigeration cycle using zeotropic mixture isobutane/pentane is carried out. The performances of different mixture compositions are compared. An exergy analysis is conducted for the cycle. The result reveals that most exergy destruction happens in the ejector, where more than 40% exergy is lost. The heat exchange in generator causes the second largest exergy loss, larger than 28%. As the mass fraction of isobutane changes ranges from 100% to 0%, the relative exergy destruction of each component is also changing. And mixture isobutane/pentane (50/50) has the maximum exergy efficiency of 7.83%. The parametric analysis of generator temperature, condenser temperature and evaporator temperature for all the mixtures shows that, all these three thermodynamic parameters have a strong effect on the cycle performance.

  5. Thermodynamic analysis of SCW NPP cycles with thermo-chemical co-generation of hydrogen

    International Nuclear Information System (INIS)

    Naidin, N.; Mokry, S.; Monichan, R.; Chophla, K.; Pioro, I.; Naterer, G.; Gabriel, K.

    2009-01-01

    Research activities are currently conducted worldwide to develop Generation IV nuclear reactor concepts with the objective of improving thermal efficiency and increasing economic competitiveness of Generation IV Nuclear Power Plants (NPPs) compared to modern thermal power plants. The Super-Critical Water-cooled Reactor (SCWR) concept is one of the six Generation IV options chosen for further investigation and development in several countries including Canada and Russia. Water-cooled reactors operating at subcritical pressures (10 - 16 MPa) have provided a significant amount of electricity production for the past 50 years. However, the thermal efficiency of the current NPPs is not very high (30 - 35%). As such, more competitive designs, with higher thermal efficiencies, which will be close to that of modern thermal power plants (45 - 50%), need to be developed and implemented. Super-Critical Water (SCW) NPPs will have much higher operating parameters compared to current NPPs (i.e., steam pressures of about 25 MPa and steam outlet temperatures up to 625 o C). Furthermore, SCWRs operating at higher temperatures can facilitate an economical co-generation of hydrogen through thermochemical cycles (particularly, the copper-chlorine cycle) or direct high-temperature electrolysis. The two SCW NPP cycles proposed by this paper are based on direct, regenerative, no-reheat and single-reheat configurations. As such, the main parameters and performance in terms of thermal efficiency of the SCW NPP concepts mentioned above are being analyzed. The cycles are generally comprised of: an SCWR, a SC turbine, one deaerator, ten feedwater heaters, and pumps. The SC turbine of the no-reheat cycle consists of one High-Pressure (HP) cylinder and two Low-Pressure (LP) cylinders. Alternatively, the SC turbine for the single-reheat cycle is comprised of one High-Pressure (HP) cylinder, one Intermediate-Pressure (IP) cylinder and two Low-Pressure (LP) cylinders. Since the single-reheat option

  6. Performance comparison and parametric optimization of subcritical Organic Rankine Cycle (ORC) and transcritical power cycle system for low-temperature geothermal power generation

    International Nuclear Information System (INIS)

    Shengjun, Zhang; Huaixin, Wang; Tao, Guo

    2011-01-01

    Research highlights: → We conduct the thermodynamic and economic performance comparison of the fluids in both subcritical ORC and transcritical power cycle. → We perform parameter optimization based on five indicators. → The optimum operation parameters and working fluids are not the same for different indicators. → The LEC value is used as the determining factor for fluids screening. → The transcritical power cycle with R125 as the working fluid was a cost-effective approach. - Abstract: Organic Rankine Cycle (ORC) is a promising technology for converting the low-grade energy to electricity. This paper presents an investigation on the parameter optimization and performance comparison of the fluids in subcritical ORC and transcritical power cycle in low-temperature (i.e. 80-100 o C) binary geothermal power system. The optimization procedure was conducted with a simulation program written in Matlab using five indicators: thermal efficiency, exergy efficiency, recovery efficiency, heat exchanger area per unit power output (APR) and the levelized energy cost (LEC). With the given heat source and heat sink conditions, performances of the working fluids were evaluated and compared under their optimized internal operation parameters. The optimum cycle design and the corresponding operation parameters were provided simultaneously. The results indicate that the choice of working fluid varies the objective function and the value of the optimized operation parameters are not all the same for different indicators. R123 in subcritical ORC system yields the highest thermal efficiency and exergy efficiency of 11.1% and 54.1%, respectively. Although the thermal efficiency and exergy efficiency of R125 in transcritical cycle is 46.4% and 20% lower than that of R123 in subcritical ORC, it provides 20.7% larger recovery efficiency. And the LEC value is relatively low. Moreover, 22032L petroleum is saved and 74,019 kg CO 2 is reduced per year when the LEC value is used as

  7. Optimization of fog inlet air cooling system for combined cycle power plants using genetic algorithm

    International Nuclear Information System (INIS)

    Ehyaei, Mehdi A.; Tahani, Mojtaba; Ahmadi, Pouria; Esfandiari, Mohammad

    2015-01-01

    In this research paper, a comprehensive thermodynamic modeling of a combined cycle power plant is first conducted and the effects of gas turbine inlet fogging system on the first and second law efficiencies and net power outputs of combined cycle power plants are investigated. The combined cycle power plant (CCPP) considered for this study consist of a double pressure heat recovery steam generator (HRSG) to utilize the energy of exhaust leaving the gas turbine and produce superheated steam to generate electricity in the Rankine cycle. In order to enhance understanding of this research and come up with optimum performance assessment of the plant, a complete optimization is using a genetic algorithm conducted. In order to achieve this goal, a new objective function is defined for the system optimization including social cost of air pollution for the power generation systems. The objective function is based on the first law efficiency, energy cost and the external social cost of air pollution for an operational system. It is concluded that using inlet air cooling system for the CCPP system and its optimization results in an increase in the average output power, first and second law efficiencies by 17.24%, 3.6% and 3.5%, respectively, for three warm months of year. - Highlights: • To model the combined cycle power plant equipped with fog inlet air cooling method. • To conduct both exergy and economic analyses for better understanding. • To conduct a complete optimization using a genetic algorithm to determine the optimal design parameters of the system

  8. Performance analysis of an absorption double-effect cycle for power and cold generation using ammonia/lithium nitrate

    International Nuclear Information System (INIS)

    Ventas, R.; Lecuona, A.; Vereda, C.; Rodriguez-Hidalgo, M.C.

    2017-01-01

    Highlights: • Two-stage double-effect cycle for combined power and cooling with flexibility. • Ammonia/lithium nitrate as solution for the absorption cycle. • Efficiency, when only producing power, of 19.5% for a generation temperature of 173 °C. • When combined cooling and power COP = 0.53 and electric efficiency of 5% for a generation temperature of 140 °C. • Better efficiencies than conventional double-effect cycles. - Abstract: The performance of a two-stage double-effect absorption machine for combined power and cold generation is proposed and studied theoretically, generating innovative schemes. The ammonia/lithium nitrate solution allows this cycle, consuming either solar thermal or residual heat. The machine is represented by means of a thermodynamic steady-state cycle. First, only power generation and only cold production are separately studied as function of the main internal temperatures, introducing the concepts of mixed and unmixed vapour and of virtual temperatures for allowing comparison. The results indicate that for producing power the efficiency of the cycle increases when rising the maximum pressure while for producing cold is the contrary. The maximum efficiency obtained for only power production with no superheating is 19.5% at a high generation temperature of 173 °C and at a moderate 20.3 bars of maximum pressure. The solution crystallization avoids a higher efficiency. The combined power and cooling cycle allows adapting the energy production to cold demand or to power demand by splitting the vapour generated. At a generation temperature of 132 °C, when splitting the vapour generated into half for power and half for cooling, the cycle obtains an electric efficiency of 6.5% and a COP of 0.52. This cycle is compared to a conventional double-effect cycle configured in parallel flow, obtaining the same electric efficiency but with a 32% higher COP.

  9. Estimation and Uncertainty Analysis of Flammability Properties for Computer-aided molecular design of working fluids for thermodynamic cycles

    DEFF Research Database (Denmark)

    Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

    Computer Aided Molecular Design (CAMD) is an important tool to generate, test and evaluate promising chemical products. CAMD can be used in thermodynamic cycle for the design of pure component or mixture working fluids in order to improve the heat transfer capacity of the system. The safety......, there is no information about the reliability of the data. Furthermore, the global optimality of the GC parameters estimation is often not ensured....

  10. Direct comparasion of an engine working under Otto, Miller end Diesel cycles : thermodynamic analysis and real engine performance

    OpenAIRE

    Ribeiro, Bernardo Sousa; Martins, Jorge

    2007-01-01

    One of the ways to improve thermodynamic efficiency of Spark Ignition engines is by the optimisation of valve timing and lift and compression ratio. The throttleless engine and the Miller cycle engine are proven concepts for efficiency improvements of such engines. This paper reports on an engine with variable valve timing (VVT) and variable compression ratio (VCR) in order to fulfill such an enhancement of efficiency. Engine load is controlled by the valve opening per...

  11. A performance analysis for MHD power cycles operating at maximum power density

    International Nuclear Information System (INIS)

    Sahin, Bahri; Kodal, Ali; Yavuz, Hasbi

    1996-01-01

    An analysis of the thermal efficiency of a magnetohydrodynamic (MHD) power cycle at maximum power density for a constant velocity type MHD generator has been carried out. The irreversibilities at the compressor and the MHD generator are taken into account. The results obtained from power density analysis were compared with those of maximum power analysis. It is shown that by using the power density criteria the MHD cycle efficiency can be increased effectively. (author)

  12. Modular Trough Power Plant Cycle and Systems Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Price, H.; Hassani, V.

    2002-01-01

    This report summarizes an analysis to reduce the cost of power production from modular concentrating solar power plants through a relatively new and exciting concept that merges two mature technologies to produce distributed modular electric power in the range of 500 to 1,500 kWe. These are the organic Rankine cycle (ORC) power plant and the concentrating solar parabolic (CSP) trough technologies that have been developed independent of each other over many years.

  13. Optimization of a recompression supercritical carbon dioxide cycle for an innovative central receiver solar power plant

    International Nuclear Information System (INIS)

    Reyes-Belmonte, M.A.; Sebastián, A.; Romero, M.; González-Aguilar, J.

    2016-01-01

    Peculiar thermodynamic properties of carbon dioxide (CO 2 ) when it is held at or above its critical condition (stated as supercritical CO 2 or sCO 2 ) have attracted the attention of many researchers. Its excellent thermophysical properties at medium-to-moderate temperature range have made it to be considered as the alternative working fluid for next power plant generation. Among those applications, future nuclear reactors, solar concentrated thermal energy or waste energy recovery have been shown as the most promising ones. In this paper, a recompression sCO 2 cycle for a solar central particles receiver application has been optimized, observing net cycle efficiency close to 50%. However, small changes on cycle parameters such as working temperatures, recuperators efficiencies or mass flow distribution between low and high temperature recuperators were found to drastically modify system overall efficiency. In order to mitigate these uncertainties, an optimization analysis based on recuperators effectiveness definition was performed observing that cycle efficiency could lie among 40%–50% for medium-to-moderate temperature range of the studied application (630 °C–680 °C). Due to the lack of maturity of current sCO 2 technologies and no power production scale demonstrators, cycle boundary conditions based on the solar application and a detailed literature review were chosen. - Highlights: • Mathematical modelling description for recompression sCO 2 cycle. • Split fraction and recuperators effectiveness effect into sCO 2 cycle performance. • Optimization methodology of sCO 2 cycle for an innovative solar central receiver. • Power generation using particles central receiver.

  14. Thermodynamic performance analysis and optimization of DMC (Dual Miller Cycle) cogeneration system by considering exergetic performance coefficient and total exergy output criteria

    International Nuclear Information System (INIS)

    Ust, Yasin; Arslan, Feyyaz; Ozsari, Ibrahim; Cakir, Mehmet

    2015-01-01

    Miller cycle engines are one of the popular engine concepts that are available for improving performance, reducing fuel consumption and NO x emissions. There are many research studies that investigated the modification of existing conventional engines for operation on a Miller cycle. In this context, a comparative performance analysis and optimization based on exergetic performance criterion, total exergy output and exergy efficiency has been carried out for an irreversible Dual–Miller Cycle cogeneration system having finite-rate of heat transfer, heat leak and internal irreversibilities. The EPC (Exergetic Performance Coefficient) criterion defined as the ratio of total exergy output to the loss rate of availability. Performance analysis has been also extended to the Otto–Miller and Diesel-Miller cogeneration cycles which may be considered as two special cases of the Dual–Miller cycle. The effect of the design parameters such as compression ratio, pressure ratio, cut-off ratio, Miller cycle ratio, heat consumer temperature ratio, allocation ratio and the ratio of power to heat consumed have also been investigated. The results obtained from this paper will provide guidance for the design of Dual–Miller Cycle cogeneration system and can be used for selection of optimal design parameters. - Highlights: • A thermodynamic performance estimation tool for DM cogeneration cycle is presented. • Using the model two special cases OM and dM cogeneration cycles can be analyzed. • The effects of r M , ψ, χ 2 and R have been investigated. • The results evaluate exergy output and environmental aspects together.

  15. Performance of ammonia–water based cycles for power generation from low enthalpy heat sources

    International Nuclear Information System (INIS)

    Mergner, Hanna; Weimer, Thomas

    2015-01-01

    Cost efficient power generation from low temperature heat sources requires an optimal usage of the available heat. In addition to the ORC (Organic Rankine Cycles), cycles with ammonia and water as working fluid show promising results regarding efficiency. Due to their non-isothermal phase change, mixtures can adapt well to a liquid heat source temperature profile and reduce the exergetic losses. In this analysis thermodynamic calculations on the layouts of two existing ammonia–water cycles are compared: a geothermal power plant based on a Siemens’ patent and a modified lab plant based on a patent invented by Kalina (KCS-34). The difference between the two cycles is the position of the internal heat recovery. Cycle simulations were carried out at defined boundary conditions in order to identify optimal operation parameters. For the selected heat source of 393.15 K (hot water) the ammonia mass fraction between 80% and 90% results in the best performance in both configurations. In general, the layout of Siemens achieves a slightly better efficiency compared to the KCS-34. Compared to an ORC using R245fa as working fluid, the exergetic efficiency can be increased by the ammonia/water based cycles by approximately 25%. - Highlights: • Two NH 3 /H 2 O based cycles based on existing plants are analyzed and compared. • A simple KCS-34 focuses on a high enthalpy difference at the turbine. • The Kalina cycle of a Siemens patent KC SG1 runs on a high vapor mass flow. • The layout of the KC SG1 shows slightly better results compared to the KCS-34. • NH 3 /H 2 O cycles show an efficiency increase compared to a regular ORC with R245fa

  16. Energy-exergy analysis of compressor pressure ratio effects on thermodynamic performance of ammonia water combined cycle

    International Nuclear Information System (INIS)

    Mohtaram, Soheil; Chen, Wen; Zargar, T.; Lin, Ji

    2017-01-01

    Highlights: • Energy exergy analysis is conducted to find the effects of RP. • EES software is utilized to perform the detailed energy-exergy analyses. • Effects investigated through energy and exergy destruction, enthalpy, yields, etc. • Detailed results are reported showing the performance of gas and combined cycle. - Abstract: The purpose of this study is to investigate the effect of compressor pressure ratio (RP) on the thermodynamic performances of ammonia-water combined cycle through energy and exergy destruction, enthalpy temperature, yields, and flow velocity. The energy-exergy analysis is conducted on the ammonia water combined cycle and the Rankine cycle, respectively. Engineering Equation Solver (EES) software is utilized to perform the detailed analyses. Values and ratios regarding heat drop and exergy loss are presented in separate tables for different equipments. The results obtained by the energy-exergy analysis indicate that by increasing the pressure ratio compressor, exergy destruction of high-pressure compressors, intercooler, gas turbine and the special produced work of gas turbine cycle constantly increase and the exergy destruction of recuperator, in contrast, decreases continuously. In addition, the least amount of input fuel into the combined cycle is observed when the pressure ratio is no less than 7.5. Subsequently, the efficiency of the cycle in gas turbine and combined cycle is reduced because the fuel input into the combined cycle is increased.

  17. Thermodynamic and energy efficiency analysis of power generation from natural salinity gradients by pressure retarded osmosis.

    Science.gov (United States)

    Yip, Ngai Yin; Elimelech, Menachem

    2012-05-01

    The Gibbs free energy of mixing dissipated when fresh river water flows into the sea can be harnessed for sustainable power generation. Pressure retarded osmosis (PRO) is one of the methods proposed to generate power from natural salinity gradients. In this study, we carry out a thermodynamic and energy efficiency analysis of PRO work extraction. First, we present a reversible thermodynamic model for PRO and verify that the theoretical maximum extractable work in a reversible PRO process is identical to the Gibbs free energy of mixing. Work extraction in an irreversible constant-pressure PRO process is then examined. We derive an expression for the maximum extractable work in a constant-pressure PRO process and show that it is less than the ideal work (i.e., Gibbs free energy of mixing) due to inefficiencies intrinsic to the process. These inherent inefficiencies are attributed to (i) frictional losses required to overcome hydraulic resistance and drive water permeation and (ii) unutilized energy due to the discontinuation of water permeation when the osmotic pressure difference becomes equal to the applied hydraulic pressure. The highest extractable work in constant-pressure PRO with a seawater draw solution and river water feed solution is 0.75 kWh/m(3) while the free energy of mixing is 0.81 kWh/m(3)-a thermodynamic extraction efficiency of 91.1%. Our analysis further reveals that the operational objective to achieve high power density in a practical PRO process is inconsistent with the goal of maximum energy extraction. This study demonstrates thermodynamic and energetic approaches for PRO and offers insights on actual energy accessible for utilization in PRO power generation through salinity gradients. © 2012 American Chemical Society

  18. Thermodynamic and economic performances optimization of an organic Rankine cycle system utilizing exhaust gas of a large marine diesel engine

    International Nuclear Information System (INIS)

    Yang, Min-Hsiung; Yeh, Rong-Hua

    2015-01-01

    Highlights: • A new parameter is proposed for optimizing economic performance of the ORC system. • Maximal thermodynamic and economic performances of an ORC system are presented. • The corresponding operating pressures in turbine of optimum thermodynamic and economic performances are investigated. • An optimal effectiveness of pre-heater is obtained for the ORC system. - Abstract: The aim of this study is to investigate the thermodynamic and economic performances optimization for an ORC system recovering the waste heat of exhaust gas from a large marine diesel engine of the merchant ship. Parameters of net power output index and thermal efficiency are used to represent the economic and thermodynamic performances, respectively. The maximum net power output index and thermal efficiency are obtained and the corresponding turbine inlet pressure, turbine outlet pressure, and effectiveness of pre-heater of the ORC system are also evaluated using R1234ze, R245fa, R600, and R600a. Furthermore, the analyses of the effects of turbine inlet temperature and cooling water temperature on the optimal economic and thermodynamic performances of the ORC system are carried out. The results show that R245fa performs the most satisfactorily followed by R600, R600a, and R1234ze under optimal economic performance. However, in the optimal thermodynamic performance evaluations, R1234ze has the largest thermal efficiency followed by R600a, R245fa, and R600. The payback periods will decrease from 0.5 year for R245fa to 0.65 year for R1234ze respectively as the system is equipped with a pre-heater. In addition, compared with conventional diesel oil feeding, the proposed ORC system can reduce 76% CO 2 emission per kilowatt-hour

  19. Report on studies on closed cycle MHD power generation; Closed cycle MHD hatsuden kento hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-04-01

    Summarized herein are results of the studies on closed cycle MHD (CCMHD) power generation by the study committee. The studied system is based on the MHD gas turbine combined Brayton cycle of about 500,000 kW in output power, firing natural gas as the fuel, and the conceptual design works therefor are completed. The major findings are: the overall plant efficiency: 54.2% at the power transmission side, plot area required per unit power output: 0.04 m{sup 2}/KW, unit construction cost: 251,000 yen/KW, and unit power generation cost: 10.2 yen/KWh. This system will be more operable than the gas turbine combined cycle with steam system, because start-up time, output change rate, optimum load and so on are constrained not on the power generator side but on the gas turbine side. The expected environmental effects include the exhaust gas NOX concentration being equivalent with that associated with the conventional power generator of 2-stage combustion system, quantity of combustion gases to be treated being approximately 40% of that associated with the gas turbine combined cycle, and reduced CO2 gas emissions, resulting from enhanced power generation efficiency. It is expected that the CCMHD system can exhibit higher efficiency than the high-temperature gas turbine combined cycle system. (NEDO)

  20. Fusion blankets for high efficiency power cycles

    International Nuclear Information System (INIS)

    Powell, J.R.; Fillo, J.A.; Horn, F.L.; Lazareth, O.W.; Usher, J.L.

    1980-04-01

    Definitions are given of 10 generic blanket types and the specific blanket chosen to be analyzed in detail from each of the 10 types. Dimensions, compositions, energy depositions and breeding ratios (where applicable) are presented for each of the 10 designs. Ultimately, based largely on neutronics and thermal hyraulics results, breeding an nonbreeding blanket options are selected for further design analysis and integration with a suitable power conversion subsystem

  1. Thermodynamics, maximum power, and the dynamics of preferential river flow structures at the continental scale

    Directory of Open Access Journals (Sweden)

    A. Kleidon

    2013-01-01

    Full Text Available The organization of drainage basins shows some reproducible phenomena, as exemplified by self-similar fractal river network structures and typical scaling laws, and these have been related to energetic optimization principles, such as minimization of stream power, minimum energy expenditure or maximum "access". Here we describe the organization and dynamics of drainage systems using thermodynamics, focusing on the generation, dissipation and transfer of free energy associated with river flow and sediment transport. We argue that the organization of drainage basins reflects the fundamental tendency of natural systems to deplete driving gradients as fast as possible through the maximization of free energy generation, thereby accelerating the dynamics of the system. This effectively results in the maximization of sediment export to deplete topographic gradients as fast as possible and potentially involves large-scale feedbacks to continental uplift. We illustrate this thermodynamic description with a set of three highly simplified models related to water and sediment flow and describe the mechanisms and feedbacks involved in the evolution and dynamics of the associated structures. We close by discussing how this thermodynamic perspective is consistent with previous approaches and the implications that such a thermodynamic description has for the understanding and prediction of sub-grid scale organization of drainage systems and preferential flow structures in general.

  2. Relation of the second law of thermodynamics to the power conversion of energy fluctuations

    International Nuclear Information System (INIS)

    Yater, J.C.

    1979-01-01

    The relation of the second law of thermodynamics to the power conversion of fluctuation energy is analyzed using the master equation of the model for the conversion circuit. The performance equation for independent particles shows that the power-conversion performance is given by the second law both for classical and quantum-effect diodes. The relation of the second law to power-conversion models based on the theoretical and experimental results for diode performance for interacting particles exhibiting many-body, multiparticle, or other anomalous and excess-current effects is examined. The performance equations are derived from the master equation for models for interacting particles to determine the conditions required by the second law for power conversion. These conditions are given in terms of the distribution throughout the power-conversion circuit for all the parameters that determine the particle and multiparticle barrier-crossing probability such as the effective mass and spectral density functions. Circuits for spectroscopic measurements for power-conversion circuits with interacting particles are noted. Using selected experimental values for the diode nonlinearity factors in these circuits, open circuit voltages are computed that are not predicted by the second law of thermodynamics

  3. Organic flash cycles for efficient power production

    Science.gov (United States)

    Ho, Tony; Mao, Samuel S.; Greif, Ralph

    2016-03-15

    This disclosure provides systems, methods, and apparatus related to an Organic Flash Cycle (OFC). In one aspect, a modified OFC system includes a pump, a heat exchanger, a flash evaporator, a high pressure turbine, a throttling valve, a mixer, a low pressure turbine, and a condenser. The heat exchanger is coupled to an outlet of the pump. The flash evaporator is coupled to an outlet of the heat exchanger. The high pressure turbine is coupled to a vapor outlet of the flash evaporator. The throttling valve is coupled to a liquid outlet of the flash evaporator. The mixer is coupled to an outlet of the throttling valve and to an outlet of the high pressure turbine. The low pressure turbine is coupled to an outlet of the mixer. The condenser is coupled to an outlet of the low pressure turbine and to an inlet of the pump.

  4. Geometrical thermodynamics and P-V criticality of the black holes with power-law Maxwell field

    Energy Technology Data Exchange (ETDEWEB)

    Hendi, S.H.; Panah, B.E. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Panahiyan, S. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Shahid Beheshti University, Physics Department, Tehran (Iran, Islamic Republic of); Talezadeh, M.S. [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of)

    2017-02-15

    We study the thermodynamical structure of Einstein black holes in the presence of power Maxwell invariant nonlinear electrodynamics for two different cases. The behavior of temperature and conditions regarding the stability of these black holes are investigated. Since the language of geometry is an effective method in general relativity, we concentrate on the geometrical thermodynamics to build a phase space for studying thermodynamical properties of these black holes. In addition, taking into account the denominator of the heat capacity, we use the proportionality between cosmological constant and thermodynamical pressure to extract the critical values for these black holes. Besides, the effects of the variation of different parameters on the thermodynamical structure of these black holes are investigated. Furthermore, some thermodynamical properties such as the volume expansion coefficient, speed of sound, and isothermal compressibility coefficient are calculated and some remarks regarding these quantities are given. (orig.)

  5. Geometrical thermodynamics and P-V criticality of the black holes with power-law Maxwell field

    International Nuclear Information System (INIS)

    Hendi, S.H.; Panah, B.E.; Panahiyan, S.; Talezadeh, M.S.

    2017-01-01

    We study the thermodynamical structure of Einstein black holes in the presence of power Maxwell invariant nonlinear electrodynamics for two different cases. The behavior of temperature and conditions regarding the stability of these black holes are investigated. Since the language of geometry is an effective method in general relativity, we concentrate on the geometrical thermodynamics to build a phase space for studying thermodynamical properties of these black holes. In addition, taking into account the denominator of the heat capacity, we use the proportionality between cosmological constant and thermodynamical pressure to extract the critical values for these black holes. Besides, the effects of the variation of different parameters on the thermodynamical structure of these black holes are investigated. Furthermore, some thermodynamical properties such as the volume expansion coefficient, speed of sound, and isothermal compressibility coefficient are calculated and some remarks regarding these quantities are given. (orig.)

  6. Comparative Life-Cycle Cost Analysis Of Solar Photovoltaic Power ...

    African Journals Online (AJOL)

    Comparative Life-Cycle Cost Analysis Of Solar Photovoltaic Power System And Diesel Generator System For Remote Residential Application In Nigeria. ... like capital cost, and diesel fuel costs are varied. The results show the photovoltaic system to be more cost-effective at low-power ranges of electrical energy supply.

  7. Analysis of a carbon dioxide transcritical power cycle using a low temperature source

    International Nuclear Information System (INIS)

    Cayer, Emmanuel; Galanis, Nicolas; Desilets, Martin; Nesreddine, Hakim; Roy, Philippe

    2009-01-01

    A detailed analysis of a carbon dioxide transcritical power cycle using an industrial low-grade stream of process gases as its heat source is presented. The methodology is divided in four steps: energy analysis, exergy analysis, finite size thermodynamics and calculation of the heat exchangers' surface. The results have been calculated for fixed temperature and mass flow rate of the heat source, fixed maximum and minimum temperatures in the cycle and a fixed sink temperature by varying the high pressure of the cycle and its net power output. The main results show the existence of an optimum high pressure for each of the four steps; in the first two steps, the optimum pressure maximises the thermal or exergetic efficiency while in the last two steps it minimises the product UA or the heat exchangers' surface. These high pressures are very similar for the energy and exergy analyses. The last two steps also have nearly identical optimizing high pressures that are significantly lower that the ones for the first two steps. In addition, the results show that the augmentation of the net power output produced from the limited energy source has no influence on the results of the energy analysis, decreases the exergetic efficiency and increases the heat exchangers' surface. Changing the net power output has no significant impact on the high pressures optimizing each of the four steps

  8. Power conversion systems based on Brayton cycles for fusion reactors

    International Nuclear Information System (INIS)

    Linares, J.I.; Herranz, L.E.; Moratilla, B.Y.; Serrano, I.P.

    2011-01-01

    This paper investigates Brayton power cycles for fusion reactors. Two working fluids have been explored: helium in classical configurations and CO 2 in recompression layouts (Feher cycle). Typical recuperator arrangements in both cycles have been strongly constrained by low temperature of some of the energy thermal sources from the reactor. This limitation has been overcome in two ways: with a combined architecture and with dual cycles. Combined architecture couples the Brayton cycle with a Rankine one capable of taking advantage of the thermal energy content of the working fluid after exiting the turbine stage (iso-butane and steam fitted best the conditions of the He and CO 2 cycles, respectively). Dual cycles set a specific Rankine cycle to exploit the lowest quality thermal energy source, allowing usual recuperator arrangements in the Brayton cycle. The results of the analyses indicate that dual cycles could reach thermal efficiencies around 42.8% when using helium, whereas thermal performance might be even better (46.7%), if a combined CO 2 -H 2 O cycle was set.

  9. Cycle improvement for nuclear steam power plant

    International Nuclear Information System (INIS)

    Silvestri, G.J. Jr.

    1976-01-01

    A pressure-increasig ejector element is disposed in an extraction line intermediate to a high pressure turbine element and a feedwater heater. The ejector utilizes high pressure fluid from a reheater drain as the motive fluid to increase the pressure at which the extraction steam is introduced into the feedwater heater. The increase in pressure of the extraction steam entering the feedwater heater due to the steam passage through the ejector increases the heat exchange capability of the extraction steam thus increasing the overall steam power plant efficiency

  10. Estimating the power efficiency of the thermal power plant modernization by using combined-cycle technologies

    International Nuclear Information System (INIS)

    Hovhannisyan, L.S.; Harutyunyan, N.R.

    2013-01-01

    The power efficiency of the thermal power plant (TPP) modernization by using combined-cycle technologies is introduced. It is shown that it is possible to achieve the greatest decrease in the specific fuel consumption at modernizing the TPP at the expense of introducing progressive 'know-how' of the electric power generation: for TPP on gas, it is combined-cycle, gas-turbine superstructures of steam-power plants and gas-turbines with heat utilization

  11. Reflections on the motive power of fire and other papers on the second law of thermodynamics

    CERN Document Server

    Carnot, Sadi

    2005-01-01

    Reflections on the Motive Power of Fire,"" along with other papers in this volume, laid the foundation of modern thermodynamics. Highly readable, ""Reflections"" contains no arguments that depend on calculus, consisting mostly of statements couched in exact language. It represents a tribute to Carnot's capacity to generalize, and to see fundamental processes at work in complex mechanisms.""Reflections on the Motive Power of Fire"" examines the relation between heat and the work done by heat in high- and low-pressure steam engines, air-engines, and an internal combustion machine. Carnot establi

  12. Low grade waste heat recovery using heat pumps and power cycles

    International Nuclear Information System (INIS)

    Bor, D.M. van de; Infante Ferreira, C.A.; Kiss, Anton A.

    2015-01-01

    Thermal energy represents a large part of the global energy usage and about 43% of this energy is used for industrial applications. Large amounts are lost via exhaust gases, liquid streams and cooling water while the share of low temperature waste heat is the largest. Heat pumps upgrading waste heat to process heat and cooling and power cycles converting waste heat to electricity can make a strong impact in the related industries. The potential of several alternative technologies, either for the upgrading of low temperature waste heat such as compression-resorption, vapor compression and trans-critical heat pumps, or for the conversion of this waste heat by using organic Rankine, Kalina and trilateral cycle engines, are investigated with regards to energetic and economic performance by making use of thermodynamic models. This study focuses on temperature levels of 45–60 °C as at this temperature range large amounts of heat are rejected to the environment but also investigates the temperature levels for which power cycles become competitive. The heat pumps deliver 2.5–11 times more energy value than the power cycles in this low temperature range at equal waste heat input. Heat engines become competitive with heat pumps at waste heat temperatures at 100 °C and above. - Highlights: • Application of heat pump technology for heating and cooling. • Compression resorption heat pumps operating with large glides approaching 100 K. • Compression-resorption heat pumps with wet compression. • Potential to convert Industrial waste heat to power or high grade heat. • Comparison between low temperature power cycles and heat pumps

  13. Osmotic Power Generation by Inner Selective Hollow Fiber Membranes: An investigation of thermodynamics, mass transfer, and module scale modelling

    KAUST Repository

    Xiong, Jun Ying; Cai, Dong Jun; Chong, Qing Yu; Lee, Swin Hui; Chung, Neal Tai-Shung

    2016-01-01

    A comprehensive analysis of fluid motion, mass transport, thermodynamics and power generation during pressure retarded osmotic (PRO) processes was conducted. This work aims to (1) elucidate the fundamental relationship among various membrane

  14. Enhancement of LNG plant propane cycle through waste heat powered absorption cooling

    International Nuclear Information System (INIS)

    Rodgers, P.; Mortazavi, A.; Eveloy, V.; Al-Hashimi, S.; Hwang, Y.; Radermacher, R.

    2012-01-01

    In liquefied natural gas (LNG) plants utilizing sea water for process cooling, both the efficiency and production capacity of the propane cycle decrease with increasing sea water temperature. To address this issue, several propane cycle enhancement approaches are investigated in this study, which require minimal modification of the existing plant configuration. These approaches rely on the use of gas turbine waste heat powered water/lithium bromide absorption cooling to either (i) subcool propane after the propane cycle condenser, or (ii) reduce propane cycle condensing pressure through pre-cooling of condenser cooling water. In the second approach, two alternative methods of pre-cooling condenser cooling water are considered, which consist of an open sea water loop, and a closed fresh water loop. In addition for all cases, three candidate absorption chiller configurations are evaluated, namely single-effect, double-effect, and cascaded double- and single-effect chillers. The thermodynamic performance of each propane cycle enhancement scheme, integrated in an actual LNG plant in the Persian Gulf, is evaluated using actual plant operating data. Subcooling propane after the propane cycle condenser is found to improve propane cycle total coefficient of performance (COP T ) and cooling capacity by 13% and 23%, respectively. The necessary cooling load could be provided by either a single-effect, double-effect or cascaded and single- and double-effect absorption refrigeration cycle recovering waste heat from a single gas turbine operated at full load. Reducing propane condensing pressure using a closed fresh water condenser cooling loop is found result in propane cycle COP T and cooling capacity enhancements of 63% and 22%, respectively, but would require substantially higher capital investment than for propane subcooling, due to higher cooling load and thus higher waste heat requirements. Considering the present trend of short process enhancement payback periods in the

  15. Automation of analytical systems in power cycles

    International Nuclear Information System (INIS)

    Staub Lukas

    2008-01-01

    'Automation' is a widely used term in instrumentation and is often applied to signal exchange, PLC and SCADA systems. Common use, however, does not necessarily described autonomous operation of analytical devices. We define an automated analytical system as a black box with an input (sample) and an output (measured value). In addition we need dedicated status lines for assessing the validities of the input for our black box and the output for subsequent systems. We will discuss input parameters, automated analytical processes and output parameters. Further considerations will be given to signal exchange and integration into the operating routine of a power plant. Local control loops (chemical dosing) and the automation of sampling systems are not discussed here. (author)

  16. Does humidification improve the micro Gas Turbine cycle? Thermodynamic assessment based on Sankey and Grassmann diagrams

    International Nuclear Information System (INIS)

    Montero Carrero, Marina; De Paepe, Ward; Bram, Svend; Parente, Alessandro; Contino, Francesco

    2017-01-01

    Highlights: •The Sankey and Grassmann diagrams of an mGT and an mHAT are drawn and presented. •Water injection leads to a 1.4% mGT electrical efficiency increase. •The saturator acts as an aftercooler enabling greater heat recovery in the recuperator. •In the saturator there is an enthalpy gain but a net exergy loss due to evaporation. •The total exergy efficiency of the mGT and mHAT are 35.7% and 30.6% respectively. -- Abstract: Despite appearing as a promising technology for decentralised Combined Heat and Power (CHP), the rather low electrical efficiency of micro Gas Turbines (mGTs) prevents them from being attractive for users with a variable heat demand. Hot water injection in mGTs, achieved by transforming the cycle into a micro Humid Air Turbine (mHAT), allows increasing the electrical efficiency of these units in moments of low heat demand—therefore decoupling heat and electricity production. This paper introduces and compares the Sankey (enthalpy flow) and Grassmann (exergy flow) diagrams of an mGT based on the Turbec T100 and the corresponding mHAT cycle. Results show that the electrical efficiency of the T100 increases by 1.4% absolute points with water injection, while the total exergy efficiency decreases by 5.1%. Although in the saturation tower there is an enthalpy gain, exergy actually decreases in this component due to the increase in entropy related to the evaporation of water. The benefits of water injection mostly rely on the increased heat capacity of the air-vapour mixture, the lower fuel consumption, the larger amount of heat recovered in the recuperator and the reduced power required in the compressor.

  17. Thermodynamic performance analysis and optimization of a solar-assisted combined cooling, heating and power system

    International Nuclear Information System (INIS)

    Wang, Jiangjiang; Lu, Yanchao; Yang, Ying; Mao, Tianzhi

    2016-01-01

    This study aims to present a thermodynamic performance analysis and to optimize the configurations of a hybrid combined cooling, heating and power (CCHP) system incorporating solar energy and natural gas. A basic natural gas CCHP system containing a power generation unit, a heat recovery system, an absorption cooling system and a storage tank is integrated with solar photovoltaic (PV) panels and/or a heat collector. Based on thermodynamic modeling, the thermodynamic performance, including energy and exergy efficiencies, under variable work conditions, such as electric load factor, solar irradiance and installation ratio, of the solar PV panels and heat collector is investigated and analyzed. The results of the energy supply side analysis indicate that the integration of solar PV into the CCHP system more efficiently improves the exergy efficiency, whereas the integration of a solar heat collector improves the energy efficiency. To match the building loads, the optimization method combined with the operation strategy is employed to optimize the system configurations to maximize the integrated benefits of energy and economic costs. The optimization results of demand–supply matching demonstrate that the integration of a solar heat collector achieves a better integrated performance than the solar PV integration in the specific case study. - Highlights: • Design a CCHP system integrated with solar PV and heat collector. • Present the energy and exergy analyses under variable work conditions. • Propose an optimization method of CCHP system for demand-supply matching.

  18. Gas--steam turbine combined cycle power plants

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J.E.

    1978-10-01

    The purpose of this technology evaluation is to provide performance and cost characteristics of the combined gas and steam turbine, cycle system applied to an Integrated Community Energy System (ICES). To date, most of the applications of combined cycles have been for electric power generation only. The basic gas--steam turbine combined cycle consists of: (1) a gas turbine-generator set, (2) a waste-heat recovery boiler in the gas turbine exhaust stream designed to produce steam, and (3) a steam turbine acting as a bottoming cycle. Because modification of the standard steam portion of the combined cycle would be necessary to recover waste heat at a useful temperature (> 212/sup 0/F), some sacrifice in the potential conversion efficiency is necessary at this temperature. The total energy efficiency ((electric power + recovered waste heat) divided by input fuel energy) varies from about 65 to 73% at full load to 34 to 49% at 20% rated electric power output. Two major factors that must be considered when installing a gas--steam turbine combines cycle are: the realiability of the gas turbine portion of the cycle, and the availability of liquid and gas fuels or the feasibility of hooking up with a coal gasification/liquefaction process.

  19. Combined Turbine and Cycle Optimization for Organic Rankine Cycle Power Systems—Part B: Application on a Case Study

    Directory of Open Access Journals (Sweden)

    Angelo La Seta

    2016-05-01

    Full Text Available Organic Rankine cycle (ORC power systems have recently emerged as promising solutions for waste heat recovery in low- and medium-size power plants. Their performance and economic feasibility strongly depend on the expander. The design process and efficiency estimation are particularly challenging due to the peculiar physical properties of the working fluid and the gas-dynamic phenomena occurring in the machine. Unlike steam Rankine and Brayton engines, organic Rankine cycle expanders combine small enthalpy drops with large expansion ratios. These features yield turbine designs with few highly-loaded stages in supersonic flow regimes. Part A of this two-part paper has presented the implementation and validation of the simulation tool TURAX, which provides the optimal preliminary design of single-stage axial-flow turbines. The authors have also presented a sensitivity analysis on the decision variables affecting the turbine design. Part B of this two-part paper presents the first application of a design method where the thermodynamic cycle optimization is combined with calculations of the maximum expander performance using the mean-line design tool described in part A. The high computational cost of the turbine optimization is tackled by building a model which gives the optimal preliminary design of an axial-flow turbine as a function of the cycle conditions. This allows for estimating the optimal expander performance for each operating condition of interest. The test case is the preliminary design of an organic Rankine cycle turbogenerator to increase the overall energy efficiency of an offshore platform. For an increase in expander pressure ratio from 10 to 35, the results indicate up to 10% point reduction in expander performance. This corresponds to a relative reduction in net power output of 8.3% compared to the case when the turbine efficiency is assumed to be 80%. This work also demonstrates that this approach can support the plant designer

  20. Power Cycling Test Method for Reliability Assessment of Power Device Modules in Respect to Temperature Stress

    DEFF Research Database (Denmark)

    Choi, Ui-Min; Blaabjerg, Frede; Jørgensen, Søren

    2018-01-01

    Power cycling test is one of the important tasks to investigate the reliability performance of power device modules in respect to temperature stress. From this, it is able to predict the lifetime of a component in power converters. In this paper, representative power cycling test circuits......, measurement circuits of wear-out failure indicators as well as measurement strategies for different power cycling test circuits are discussed in order to provide the current state of knowledge of this topic by organizing and evaluating current literature. In the first section of this paper, the structure...... of a conventional power device module and its related wear-out failure mechanisms with degradation indicators are discussed. Then, representative power cycling test circuits are introduced. Furthermore, on-state collector-emitter voltage (VCE ON) and forward voltage (VF) measurement circuits for wear-out condition...

  1. Electrochemical thermodynamic measurement system

    Science.gov (United States)

    Reynier, Yvan [Meylan, FR; Yazami, Rachid [Los Angeles, CA; Fultz, Brent T [Pasadena, CA

    2009-09-29

    The present invention provides systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and electrochemical energy storage and conversion systems. Systems and methods of the present invention are configured for simultaneously collecting a suite of measurements characterizing a plurality of interconnected electrochemical and thermodynamic parameters relating to the electrode reaction state of advancement, voltage and temperature. Enhanced sensitivity provided by the present methods and systems combined with measurement conditions that reflect thermodynamically stabilized electrode conditions allow very accurate measurement of thermodynamic parameters, including state functions such as the Gibbs free energy, enthalpy and entropy of electrode/electrochemical cell reactions, that enable prediction of important performance attributes of electrode materials and electrochemical systems, such as the energy, power density, current rate and the cycle life of an electrochemical cell.

  2. Ideal cycle analysis of a regenerative pulse detonation engine for power production

    Science.gov (United States)

    Bellini, Rafaela

    Over the last few decades, considerable research has been focused on pulse detonation engines (PDEs) as a promising replacement for existing propulsion systems with potential applications in aircraft ranging from the subsonic to the lower hypersonic regimes. On the other hand, very little attention has been given to applying detonation for electric power production. One method for assessing the performance of a PDE is through thermodynamic cycle analysis. Earlier works have adopted a thermodynamic cycle for the PDE that was based on the assumption that the detonation process could be approximated by a constant volume process, called the Humphrey cycle. The Fickett-Jacob cycle, which uses the one--dimensional Chapman--Jouguet (CJ) theory of detonation, has also been used to model the PDE cycle. However, an ideal PDE cycle must include a detonation based compression and heat release processes with a finite chemical reaction rate that is accounted for in the Zeldovich -- von Neumann -- Doring model of detonation where the shock is considered a discontinuous jump and is followed by a finite exothermic reaction zone. This work presents a thermodynamic cycle analysis for an ideal PDE cycle for power production. A code has been written that takes only one input value, namely the heat of reaction of a fuel-oxidizer mixture, based on which the program computes all the points on the ZND cycle (both p--v and T--s plots), including the von Neumann spike and the CJ point along with all the non-dimensionalized state properties at each point. In addition, the program computes the points on the Humphrey and Brayton cycles for the same input value. Thus, the thermal efficiencies of the various cycles can be calculated and compared. The heat release of combustion is presented in a generic form to make the program usable with a wide variety of fuels and oxidizers and also allows for its use in a system for the real time monitoring and control of a PDE in which the heat of reaction

  3. Thermodynamic analysis of the use a chemical heat pump to link a supercritical water-cooled nuclear reactor and a thermochemical water-splitting cycle for hydrogen production

    International Nuclear Information System (INIS)

    Granovskii, Mikhail; Dincer, Ibrahim; Rosen, Marc A.; Pioro, Igor

    2008-01-01

    Increases in the power generation efficiency of nuclear power plants (NPPs) are mainly limited by the permissible temperatures in nuclear reactors and the corresponding temperatures and pressures of the coolants in reactors. Coolant parameters are limited by the corrosion rates of materials and nuclear-reactor safety constraints. The advanced construction materials for the next generation of CANDU reactors, which employ supercritical water (SCW) as a coolant and heat carrier, permit improved 'steam' parameters (outlet temperatures up to 625degC and pressures of about 25 MPa). An increase in the temperature of steam allows it to be utilized in thermochemical water splitting cycles to produce hydrogen. These methods are considered by many to be among the most efficient ways to produce hydrogen from water and to have advantages over traditional low-temperature water electrolysis. However, even lower temperature water splitting cycles (Cu-Cl, UT-3, etc.) require an intensive heat supply at temperatures higher than 550-600degC. A sufficient increase in the heat transfer from the nuclear reactor to a thermochemical water splitting cycle, without jeopardizing nuclear reactor safety, might be effectively achieved by application of a heat pump, which increases the temperature of the heat supplied by virtue of a cyclic process driven by mechanical or electrical work. Here, a high-temperature chemical heat pump, which employs the reversible catalytic methane conversion reaction, is proposed. The reaction shift from exothermic to endothermic and back is achieved by a change of the steam concentration in the reaction mixture. This heat pump, coupled with the second steam cycle of a SCW nuclear power generation plant on one side and a thermochemical water splitting cycle on the other, increases the temperature of the 'nuclear' heat and, consequently, the intensity of heat transfer into the water splitting cycle. A comparative preliminary thermodynamic analysis is conducted of

  4. Performance review: PBMR closed cycle gas turbine power plant

    International Nuclear Information System (INIS)

    Pradeep Kumar, K.N.; Tourlidakis, A.; Pilidis, P.

    2001-01-01

    Helium is considered as one of the ideal working fluid for closed cycle using nuclear heat source due to its low neutron absorption as well as high thermodynamic properties. The commercial viability of the Helium turbo machinery depends on operational success. The past attempts failed due to poor performances manifested in the form of drop in efficiency, inability to reach maximum load, slow response to the transients etc. Radical changes in the basic design were suggested in some instances as possible solutions. A better understanding of the operational performance is necessary for the detailed design of the plant and the control systems. This paper describes the theory behind the off design and transient modelling of a closed cycle gas turbine plant. A computer simulation model has been created specifically for this cycle. The model has been tested for various turbine entry temperatures along the steady state and its replications at various locations were observed. The paper also looks at the various control methods available for a closed cycle and some of the options were simulated. (author)

  5. Thermodynamic and heat transfer analysis of heat recovery from engine test cell by Organic Rankine Cycle

    Science.gov (United States)

    Shokati, Naser; Mohammadkhani, Farzad; Farrokhi, Navid; Ranjbar, Faramarz

    2014-12-01

    During manufacture of engines, evaluation of engine performance is essential. This is accomplished in test cells. During the test, a significant portion of heat energy released by the fuel is wasted. In this study, in order to recover these heat losses, Organic Rankine Cycle (ORC) is recommended. The study has been conducted assuming the diesel oil to be composed of a single hydrocarbon such as C12H26. The composition of exhaust gases (products of combustion) have been computed (and not determined experimentally) from the stoichiometric equation representing the combustion reaction. The test cell heat losses are recovered in three separate heat exchangers (preheater, evaporator and superheater). These heat exchangers are separately designed, and the whole system is analyzed from energy and exergy viewpoints. Finally, a parametric study is performed to investigate the effect of different variables on the system performance characteristics such as the ORC net power, heat exchangers effectiveness, the first law efficiency, exergy destruction and heat transfer surfaces. The results of the study show that by utilizing ORC, heat recovery equivalent to 8.85 % of the engine power is possible. The evaporator has the highest exergy destruction rate, while the pump has the lowest among the system components. Heat transfer surfaces are calculated to be 173.6, 58.7, and 11.87 m2 for the preheater, evaporator and superheater, respectively.

  6. Cycling of conventional power plants: Technical limits and actual costs

    International Nuclear Information System (INIS)

    Van den Bergh, Kenneth; Delarue, Erik

    2015-01-01

    Highlights: • Literature reports a wide range of cycling parameters (technical and cost-related). • The impact of different cycling parameters is assessed. • The German 2013 system is studied as a case study. • Even for stringent parameters, the dynamic limit of the portfolio is not reached. • Cycling costs can be reduced with 40% when taken into account in the scheduling. - Abstract: Cycling of conventional generation units is an important source of operational flexibility in the electricity generation system. Cycling is changing the power output of conventional units by means of ramping and switching (starting up and shutting down). In the literature, a wide range of technical and cost-related cycling parameters can be found. Different studies allocate different cycling parameters to similar generation units. This paper assesses the impact of different cycling parameters allocated to a conventional generation portfolio. Both the technical limitations of power plants and all costs related to cycling are considered. The results presented in this paper follow from a unit commitment model, used for a case study based on the German 2013 system. The conventional generation portfolio has to deliver different residual load time series, corresponding to different levels of renewables penetration. The study shows, under the assumptions made, that although the dynamic limits of some units are reached, the limits of the conventional generation portfolio as a whole are not reached, even if stringent dynamic parameters are assigned to the generation portfolio and a highly variable residual load is imposed to the system. The study shows also the importance of including full cycling costs in the unit commitment scheduling. The cycling cost can be reduced by up to 40% when fully taken into account

  7. Thermodynamic analysis of a fuel cell power system for transportation applications

    International Nuclear Information System (INIS)

    Hussain, M.M.; Baschuk, J.J.; Li, X.; Dincer, I.

    2004-01-01

    This study deals with the thermodynamic modeling of a polymer electrolyte membrane (PEM) fuel cell power system for transportation applications. The PEM fuel cell performance model developed previously by two of the authors is incorporated into the present model. The analysis includes the operation of all the components in the system, which consists of two major modules: PEM fuel cell stack module and system module and a cooling pump. System module includes air compressor, heat exchanger, humidifier and a cooling loop. A parametric study is performed to examine the effect of varying operating conditions (e.g., temperature pressure and air stoichiometry) on the energy and exergy efficiencies of the system. Further, thermodynamic irreversibilities in each component of the system are determined. It is found that, with the increase of external load (current density), the difference between the gross stack power and net system power increases. The largest irreversibility rate occurs in the fuel cell stack. Thus, minimization of irreversibility rate in the fuel cell stack is essential to enhance the performance of the system, which in turn reduces the cost and helps in commercialization of fuel cell power system in transportation applications. (author)

  8. Assessment of the thorium fuel cycle in power reactors

    International Nuclear Information System (INIS)

    Kasten, P.R.; Homan, F.J.; Allen, E.J.

    1977-01-01

    A study was conducted at Oak Ridge National Laboratory to evaluate the role of thorium fuel cycles in power reactors. Three thermal reactor systems were considered: Light Water Reactors (LWRs); High-Temperature Gas-Cooled Reactors (HTGRs); and Heavy Water Reactors (HWRs) of the Canadian Deuterium Uranium Reactor (CANDU) type; most of the effort was on these systems. A summary comparing thorium and uranium fuel cycles in Fast Breeder Reactors (FBRs) was also compiled

  9. INTEGRATED PYROLYSIS COMBINED CYCLE BIOMASS POWER SYSTEM CONCEPT DEFINITION

    International Nuclear Information System (INIS)

    Sandvig, Eric; Walling, Gary; Brown, Robert C.; Pletka, Ryan; Radlein, Desmond; Johnson, Warren

    2003-01-01

    Advanced power systems based on integrated gasification/combined cycles (IGCC) are often presented as a solution to the present shortcomings of biomass as fuel. Although IGCC has been technically demonstrated at full scale, it has not been adopted for commercial power generation. Part of the reason for this situation is the continuing low price for coal. However, another significant barrier to IGCC is the high level of integration of this technology: the gas output from the gasifier must be perfectly matched to the energy demand of the gas turbine cycle. We are developing an alternative to IGCC for biomass power: the integrated (fast) pyrolysis/ combined cycle (IPCC). In this system solid biomass is converted into liquid rather than gaseous fuel. This liquid fuel, called bio-oil, is a mixture of oxygenated organic compounds and water that serves as fuel for a gas turbine topping cycle. Waste heat from the gas turbine provides thermal energy to the steam turbine bottoming cycle. Advantages of the biomass-fueled IPCC system include: combined cycle efficiency exceeding 37 percent efficiency for a system as small as 7.6 MW e ; absence of high pressure thermal reactors; decoupling of fuel processing and power generation; and opportunities for recovering value-added products from the bio-oil. This report provides a technical overview of the system including pyrolyzer design, fuel clean-up strategies, pyrolysate condenser design, opportunities for recovering pyrolysis byproducts, gas turbine cycle design, and Rankine steam cycle. The report also reviews the potential biomass fuel supply in Iowa, provide and economic analysis, and present a summery of benefits from the proposed system

  10. INTEGRATED PYROLYSIS COMBINED CYCLE BIOMASS POWER SYSTEM CONCEPT DEFINITION

    Energy Technology Data Exchange (ETDEWEB)

    Eric Sandvig; Gary Walling; Robert C. Brown; Ryan Pletka; Desmond Radlein; Warren Johnson

    2003-03-01

    Advanced power systems based on integrated gasification/combined cycles (IGCC) are often presented as a solution to the present shortcomings of biomass as fuel. Although IGCC has been technically demonstrated at full scale, it has not been adopted for commercial power generation. Part of the reason for this situation is the continuing low price for coal. However, another significant barrier to IGCC is the high level of integration of this technology: the gas output from the gasifier must be perfectly matched to the energy demand of the gas turbine cycle. We are developing an alternative to IGCC for biomass power: the integrated (fast) pyrolysis/ combined cycle (IPCC). In this system solid biomass is converted into liquid rather than gaseous fuel. This liquid fuel, called bio-oil, is a mixture of oxygenated organic compounds and water that serves as fuel for a gas turbine topping cycle. Waste heat from the gas turbine provides thermal energy to the steam turbine bottoming cycle. Advantages of the biomass-fueled IPCC system include: combined cycle efficiency exceeding 37 percent efficiency for a system as small as 7.6 MW{sub e}; absence of high pressure thermal reactors; decoupling of fuel processing and power generation; and opportunities for recovering value-added products from the bio-oil. This report provides a technical overview of the system including pyrolyzer design, fuel clean-up strategies, pyrolysate condenser design, opportunities for recovering pyrolysis byproducts, gas turbine cycle design, and Rankine steam cycle. The report also reviews the potential biomass fuel supply in Iowa, provide and economic analysis, and present a summery of benefits from the proposed system.

  11. sCO2 Power Cycles Summit Summary November 2017.

    Energy Technology Data Exchange (ETDEWEB)

    Mendez Cruz, Carmen Margarita; Rochau, Gary E.; Lance, Blake

    2018-04-01

    Over the past ten years, the Department of Energy (DOE) has helped to develop components and technologies for the Supercritical Carbon Dioxide (sCO2) power cycle capable of efficient operation at high temperatures and high efficiency. The DOE Offices of Fossil Energy, Nuclear Energy, and Energy Efficiency and Renewable Energy collaborated in the planning and execution of the sCO2 Power Cycle Summit conducted in Albuquerque, NM in November 2017. The summit brought together participants from government, national laboratories, research, and industry to engage in discussions regarding the future of sCO 2 Power Cycles Technology. This report summarizes the work involved in summit planning and execution, before, during, and after the event, including the coordination between three DOE offices and technical content presented at the event.

  12. Power generation costs for alternate reactor fuel cycles

    International Nuclear Information System (INIS)

    Smolen, G.R.; Delene, J.G.

    1980-09-01

    The total electric generating costs at the power plant busbar are estimated for various nuclear reactor fuel cycles which may be considered for power generation in the future. The reactor systems include pressurized water reactors (PWR), heavy-water reactors (HWR), high-temperature gas cooled reactors (HTGR), liquid-metal fast breeder reactors (LMFBR), light-water pre-breeder and breeder reactors (LWPR, LWBR), and a fast mixed spectrum reactor (FMSR). Fuel cycles include once-through, uranium-only recycle, and full recycle of the uranium and plutonium in the spent fuel assemblies. The U 3 O 8 price for economic transition from once-through LWR fuel cycles to both PWR recycle and LMFBR systems is estimated. Electric power generation costs were determined both for a reference set of unit cost parameters and for a range of uncertainty in these parameters. In addition, cost sensitivity parameters are provided so that independent estimations can be made for alternate cost assumptions

  13. To Estimation of Efficient Usage of Organic Fuel in the Cycle of Steam Power Installations

    Directory of Open Access Journals (Sweden)

    A. P. Nesenchuk

    2013-01-01

    Full Text Available Tendencies of power engineering development in the world were shown in this article. There were carried out the thermodynamic Analysis of efficient usage of different types of fuel. This article shows the obtained result, which reflects that low-calorie fuel (from the point of thermodynamics is more efficient to use at steam power stations then high-energy fuel.

  14. Simulation and parametric optimisation of thermal power plant cycles

    Directory of Open Access Journals (Sweden)

    P. Ravindra Kumar

    2016-09-01

    Full Text Available The objective of the paper is to analyse parametric studies and optimum steam extraction pressures of three different (subcritical, supercritical and ultra-supercritical coal fired power plant cycles at a particular main steam temperature of 600 °C by keeping the reheat temperature at 537 °C and condenser pressure at 0.09 bar as constant. In order to maximize the heat rate gain possible with supercritical and ultra-supercritical steam conditions, eight stages of feed water heater arrangement with single reheater is considered. The system is optimized in such a way that the percentage exergetic losses are reduced for the increase of the exergetic efficiency and higher fuel utilization. The plant cycles are simulated and optimized by using Cycle Tempo 5.0 simulation software tool. From the simulation study, it is observed that the thermal efficiency of the three different power plant cycles obtained as 41.40, 42.48 and 43.03%, respectively. The specific coal consumption for three different power plant cycles are 0.56, 0.55 and 0.54 Tonnes/MWh. The improvement in feed water temperatures at the inlet of steam generator of respective cycles are 291, 305 and 316 °C.

  15. Nuclear power and the possibility of alternative fuel cycles

    International Nuclear Information System (INIS)

    Engelmann, P.

    1979-01-01

    Concern about the societal implications, potential risks and the possibility of nuclear weapons proliferation has slowed down the growth of nuclear energy. Assuming a further moderate growth of nuclear power in the Federal Republic of Germany several fuel cycle and reactor strategies can the followed without exhausting the nuclear the resources before the year 2100. The uranium demand of various reactor strategies with LWR's FBR's and HTR's is compared for two demand cases in the FRG. While recycling of spent fuel seems necessary in any case, it is shown that the Th/U cycle can provide a realistic alternative to the U/Pu cycle. The parallel introduction of both cycles appears as the best solution, as it reduces the overall risks and leads to minimum uranium demand. The risk of nuclear proliferation does not vary considerably with the fuel cycle applied; it can, however, be reduced to acceptable levels by safeguards methods and institutional means. (orig.) [de

  16. Comparison of Optimal Thermodynamic Models of the Tricarboxylic Acid Cycle from Heterotrophs, Cyanobacteria, and Green Sulfur Bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Dennis G.; Jaramillo Riveri, Sebastian I.; Baxter, Douglas J.; Cannon, William R.

    2014-12-15

    We have applied a new stochastic simulation approach to predict the metabolite levels, energy flow, and material flux in the different oxidative TCA cycles found in E. coli and Synechococcus sp. PCC 7002, and in the reductive TCA cycle typical of chemolithoautotrophs and phototrophic green sulfur bacteria such as Chlorobaculum tepidum. The simulation approach is based on equations of state and employs an assumption similar to that used in transition state theory. The ability to evaluate the thermodynamics of metabolic pathways allows one to understand the relationship between coupling of energy and material gradients in the environment and the selforganization of stable biological systems, and it is shown that each cycle operates in the direction expected due to its environmental niche. The simulations predict changes in metabolite levels and flux in response to changes in cofactor concentrations that would be hard to predict without an elaborate model based on the law of mass action. In fact, we show that a thermodynamically unfavorable reaction can still have flux in the forward direction when it is part of a reaction network. The ability to predict metabolite levels, energy flow and material flux should be significant for understanding the dynamics of natural systems and for understanding principles for engineering organisms for production of specialty chemicals, such as biofuels.

  17. 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.

  18. Life cycle analysis of advanced nuclear power generation technologies

    International Nuclear Information System (INIS)

    Uchiyama, Yoji; Yokoyama, Hayaichi

    1996-01-01

    In this research, as for light water reactors and fast breeder reactors, for the object of all the processes from the mining, transport and refining of fuel, electric power generation to the treatment and disposal of waste, the amount of energy input and the quantity of CO 2 emission over the life cycle were analyzed, and regarding the influence that the technical progress of nuclear power generation exerted to environment, the effect of improvement was elucidated. Attention has been paid to nuclear power generation as its CO 2 emission is least, and the effect of global warming is smallest. In order to reduce the quantity of radioactive waste generation in LWRs and the cost of fuel cycle, and to extend the operation cycle, the technical development for heightening fuel burnup is in progress. The process of investigation of the new technologies of nuclear power generation taken up in this research is described. The analysis of the energy balance of various power generation methods is discussed. In the case of pluthermal process, the improvement of energy balance ratio is dependent on uranium enrichment technology. Nuclear power generation requires much materials and energy for the construction, and emits CO 2 indirectly. The CO 2 unit emission based on the analysis of energy balance was determined for the new technologies of nuclear power generation, and the results are shown. (K.I.)

  19. Riemannian geometry of thermodynamics and systems with repulsive power-law interactions.

    Science.gov (United States)

    Ruppeiner, George

    2005-07-01

    A Riemannian geometric theory of thermodynamics based on the postulate that the curvature scalar R is proportional to the inverse free energy density is used to investigate three-dimensional fluid systems of identical classical point particles interacting with each other via a power-law potential energy gamma r(-alpha) . Such systems are useful in modeling melting transitions. The limit alpha-->infinity corresponds to the hard sphere gas. A thermodynamic limit exists only for short-range (alpha>3) and repulsive (gamma>0) interactions. The geometric theory solutions for given alpha>3 , gamma>0 , and any constant temperature T have the following properties: (1) the thermodynamics follows from a single function b (rho T(-3/alpha) ) , where rho is the density; (2) all solutions are equivalent up to a single scaling constant for rho T(-3/alpha) , related to gamma via the virial theorem; (3) at low density, solutions correspond to the ideal gas; (4) at high density there are solutions with pressure and energy depending on density as expected from solid state physics, though not with a Dulong-Petit heat capacity limit; (5) for 33.7913 a phase transition is required to go between these regimes; (7) for any alpha>3 we may include a first-order phase transition, which is expected from computer simulations; and (8) if alpha-->infinity, the density approaches a finite value as the pressure increases to infinity, with the pressure diverging logarithmically in the density difference.

  20. Thermodynamics analysis of a modified dual-evaporator CO2 transcritical refrigeration cycle with two-stage ejector

    International Nuclear Information System (INIS)

    Bai, Tao; Yan, Gang; Yu, Jianlin

    2015-01-01

    In this paper, a modified dual-evaporator CO 2 transcritical refrigeration cycle with two-stage ejector (MDRC) is proposed. In MDRC, the two-stage ejector are employed to recover the expansion work from cycle throttling processes and enhance the system performance and obtain dual-temperature refrigeration simultaneously. The effects of some key parameters on the thermodynamic performance of the modified cycle are theoretically investigated based on energetic and exergetic analyses. The simulation results for the modified cycle show that two-stage ejector exhibits more effective system performance improvement than the single ejector in CO 2 dual-temperature refrigeration cycle, and the improvements of the maximum system COP (coefficient of performance) and system exergy efficiency could reach 37.61% and 31.9% over those of the conventional dual-evaporator cycle under the given operating conditions. The exergetic analysis for each component at optimum discharge pressure indicates that the gas cooler, compressor, two-stage ejector and expansion valves contribute main portion to the total system exergy destruction, and the exergy destruction caused by the two-stage ejector could amount to 16.91% of the exergy input. The performance characteristics of the proposed cycle show its promise in dual-evaporator refrigeration system. - Highlights: • Two-stage ejector is used in dual-evaporator CO 2 transcritical refrigeration cycle. • Energetic and exergetic methods are carried out to analyze the system performance. • The modified cycle could obtain dual-temperature refrigeration simultaneously. • Two-stage ejector could effectively improve system COP and exergy efficiency

  1. Power plant cycle chemistry - a currently neglected power plant chemistry discipline

    International Nuclear Information System (INIS)

    Bursik, A.

    2005-01-01

    Power plant cycle chemistry seems to be a stepchild at both utilities and universities and research organizations. It is felt that other power plant chemistry disciplines are more important. The last International Power Cycle Chemistry Conference in Prague may be cited as an example. A critical review of the papers presented at this conference seems to confirm the above-mentioned statements. This situation is very unsatisfactory and has led to an increasing number of component failures and instances of damage to major cycle components. Optimization of cycle chemistry in fossil power plants undoubtedly results in clear benefits and savings with respect to operating costs. It should be kept in mind that many seemingly important chemistry-related issues lose their importance during forced outages of units practicing faulty plant cycle chemistry. (orig.)

  2. Involvement of Thermodynamic Cycle Analysis in a Concurrent Approach to Reciprocating Engine Design

    Directory of Open Access Journals (Sweden)

    J. Macek

    2001-01-01

    Full Text Available A modularised approach to thermodynamic optimisation of new concepts of volumetric combustion engines concerning efficiency and emissions is outlined. Levels of primary analysis using a computerised general-change entropy diagram and detailed multizone, 1 to 3-D finite volume methods are distinguished. The use of inverse algorithms based on the same equations is taken into account.

  3. Thermodynamic efficiency analysis and cycle optimization of deeply precooled combined cycle engine in the air-breathing mode

    Science.gov (United States)

    Zhang, Jianqiang; Wang, Zhenguo; Li, Qinglian

    2017-09-01

    The efficiency calculation and cycle optimization were carried out for the Synergistic Air-Breathing Rocket Engine (SABRE) with deeply precooled combined cycle. A component-level model was developed for the engine, and exergy efficiency analysis based on the model was carried out. The methods to improve cycle efficiency have been proposed. The results indicate cycle efficiency of SABRE is between 29.7% and 41.7% along the flight trajectory, and most of the wasted exergy is occupied by the unburned hydrogen in exit gas. Exergy loss exists in each engine component, and the sum losses of main combustion chamber(CC), pre-burner(PB), precooler(PC) and 3# heat exchanger(HX3) are greater than 71.3% of the total loss. Equivalence ratio is the main influencing factor of cycle, and it can be regulated by adjusting parameters of helium loop. Increase the maximum helium outlet temperature of PC by 50 K, the total assumption of hydrogen will be saved by 4.8%, and the cycle efficiency is advanced by 3% averagely in the trajectory. Helium recirculation scheme introduces a helium recirculation loop to increase local helium flow rate of PC. It turns out the total assumption of hydrogen will be saved by 9%, that's about 1740 kg, and the cycle efficiency is advanced by 5.6% averagely.

  4. The wet compression technology for gas turbine power plants: Thermodynamic model

    International Nuclear Information System (INIS)

    Bracco, Stefano; Pierfederici, Alessandro; Trucco, Angela

    2007-01-01

    This paper examines from a thermodynamic point of view the effects of wet compression on gas turbine power plants, particularly analysing the influence of ambient conditions on the plant performance. The results of the mathematical model, implemented in 'Matlab' software, have been compared with the simulation results presented in literature and in particular the values of the 'evaporative rate', proposed in Araimo et al. [L. Araimo, A. Torelli, Thermodynamic analysis of the wet compression process in heavy duty gas turbine compressors, in: Proceedings of the 59th ATI Annual Congress, Genova, 2004, pp. 1249-1263; L. Araimo, A. Torelli, Wet compression technology applied to heavy duty gas turbines - GT power augmentation and efficiency upgrade, in: Proceedings of the 59th ATI Annual Congress, Genova, 2004, pp. 1265-1277] by 'Gas Turbines Department' of Ansaldo Energia S.p.A., have been taken into account to validate the model. The simulator permits to investigate the effects of the fogging and wet compression techniques and estimate the power and efficiency gain of heavy duty gas turbines operating in hot and arid conditions

  5. Nuclear power generation and fuel cycle report 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-10-01

    This report presents the current status and projections through 2015 of nuclear capacity, generation, and fuel cycle requirements for all countries using nuclear power to generate electricity for commercial use. It also contains information and forecasts of developments in the worldwide nuclear fuel market. Long term projections of U.S. nuclear capacity, generation, and spent fuel discharges for two different scenarios through 2040 are developed. A discussion on decommissioning of nuclear power plants is included.

  6. Nuclear power generation and fuel cycle report 1996

    International Nuclear Information System (INIS)

    1996-10-01

    This report presents the current status and projections through 2015 of nuclear capacity, generation, and fuel cycle requirements for all countries using nuclear power to generate electricity for commercial use. It also contains information and forecasts of developments in the worldwide nuclear fuel market. Long term projections of U.S. nuclear capacity, generation, and spent fuel discharges for two different scenarios through 2040 are developed. A discussion on decommissioning of nuclear power plants is included

  7. Thermodynamic Analysis of a Steam Power Plant with Double Reheat and Feed Water Heaters

    Directory of Open Access Journals (Sweden)

    M. M. Rashidi

    2014-03-01

    Full Text Available A steam cycle with double reheat and turbine extraction is presented. Six heaters are used, three of them at high pressure and the other three at low pressure with deaerator. The first and second law analysis for the cycle and optimization of the thermal and exergy efficiencies are investigated. An exergy analysis is performed to guide the thermodynamic improvement for this cycle. The exergy and irreversibility analyses of each component of the cycle are determined. Effects of turbine inlet pressure, boiler exit steam temperature, and condenser pressure on the first and second laws' efficiencies are investigated. Also the best turbine extraction pressure on the first law efficiency is obtained. The results show that the biggest exergy loss occurs in the boiler followed by the turbine. The results also show that the overall thermal efficiency and the second law efficiency decrease as the condenser pressure increases for any fixed outlet boiler temperature, however, they increase as the boiler temperature increases for any condenser pressure. Furthermore, the best values of extraction pressure from high, intermediate, and low pressure turbine which give the maximum first law efficiencies are obtained based on the required heat load corresponding to each exit boiler temperature.

  8. Thermodynamic analysis of combined cycle under design/off-design conditions for its efficient design and operation

    International Nuclear Information System (INIS)

    Zhang, Guoqiang; Zheng, Jiongzhi; Xie, Angjun; Yang, Yongping; Liu, Wenyi

    2016-01-01

    Highlights: • Based on the PG9351FA gas turbine, two gas-steam combined cycles are redesigned. • Analysis of detailed off-design characteristics of the combined cycle main parts. • Suggestions for improving design and operation performance of the combined cycle. • Higher design efficiency has higher off-design efficiency in general PR range. • High pressure ratio combined cycles possess good off-design performance. - Abstract: To achieve a highly efficient design and operation of combined cycles, this study analyzed in detail the off-design characteristics of the main components of three combined cycles with different compressor pressure ratios (PRs) based on real units. The off-design model of combined cycle was built consisting of a compressor, a combustor, a gas turbine, and a heat recovery steam generator (HRSG). The PG9351FA unit is selected as the benchmark unit, on the basis of which the compressor is redesigned with two different PRs. Then, the design/off-design characteristics of the three units with different design PRs and the interactive relations between topping and bottoming cycles are analyzed with the same turbine inlet temperature (TIT). The results show that the off-design characteristics of the topping cycle affect dramatically the combined cycle performance. The variation range of the exergy efficiency of the topping cycle for the three units is between 11.9% and 12.4% under the design/off-design conditions. This range is larger than that of the bottoming cycle (between 9.2% and 9.5%). The HRSG can effectively recycle the heat/heat exergy of the gas turbine exhaust. Comparison among the three units shows that for a traditional gas-steam combined cycle, a high design efficiency results in a high off-design efficiency in the usual PR range. The combined cycle design efficiency of higher pressure ratio is almost equal to that of the PG9351FA, but its off-design efficiency is higher (maximum 0.42%) and the specific power decreases. As for

  9. Thermodynamic optimisation and analysis of four Kalina cycle layouts for high temperature applications

    DEFF Research Database (Denmark)

    Modi, Anish; Haglind, Fredrik

    2015-01-01

    The Kalina cycle has seen increased interest in the last few years as an efficient alternative to the conventional steam Rankine cycle. However, the available literature gives little information on the algorithms to solve or optimise this inherently complex cycle. This paper presents a detailed a...

  10. Thermodynamics II essentials

    CERN Document Server

    REA, The Editors of

    2013-01-01

    REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Thermodynamics II includes review of thermodynamic relations, power and refrigeration cycles, mixtures and solutions, chemical reactions, chemical equilibrium, and flow through nozzl

  11. Fast thermal cycling-enhanced electromigration in power metallization

    NARCIS (Netherlands)

    Nguyen, Van Hieu; Salm, Cora; Krabbenborg, B.H.; Krabbenborg, B.H.; Bisschop, J.; Mouthaan, A.J.; Kuper, F.G.

    Fast thermal nterconnects used in power ICs are susceptible to short circuit failure due to a combination of fast thermal cycling and electromigration stresses. In this paper, we present a study of electromigration-induced extrusion short-circuit failure in a standard two level metallization

  12. Improvements in steam cycle electric power generating plants

    International Nuclear Information System (INIS)

    Bienvenu, Claude.

    1973-01-01

    The invention relates to a steam cycle electric energy generating plants of the type comprising a fossil or nuclear fuel boiler for generating steam and a turbo alternator group, the turbine of which is fed by the boiler steam. The improvement is characterized in that use is made of a second energy generating group in which a fluid (e.g. ammoniac) undergoes a condensation cycle the heat source of said cycle being obtained through a direct or indirect heat exchange with a portion of the boiler generated steam whereby it is possible without overloading the turbo-alternator group, to accomodate any increase of the boiler power resulting from the use of another fuel while maintaining a maximum energy output. This can be applied to electric power stations [fr

  13. A technical and financial analysis of two recuperated, reciprocating engine driven power plants. Part 1: Thermodynamic analysis

    International Nuclear Information System (INIS)

    Orbaiz, Pedro Jose; Brear, Michael J.

    2014-01-01

    Highlights: • A thermodynamic analysis of two recuperated ICE plants is undertaken. • The overall plant efficiency and CO 2 emissions are analysed. • Chemical recuperation without a secondary heat source is unlikely. • Using a renewable secondary heat source reduces the CO 2 emission of the plant. - Abstract: This paper is the first of a two part study that analyses the technical and financial performance of particular, recuperated engine systems. This first paper presents a thermodynamic study of two systems. The first system involves the chemical recuperation of a reciprocating, spark ignited, internal combustion engine using only the waste heat of the engine to power a steam–methane reformer. The performance of this system is evaluated for different coolant loads and steam–methane ratios. The second system is a so-called ’hybrid’ in which not only the waste heat of the engine is used, but also a secondary heat source – the combustion of biomass. The effects of the reformer’s temperature and the steam–methane ratio on the system performance are analysed. These analyses show that the potential efficiency improvement obtained when using only the engine waste heat to power the recuperation is marginal. However, results for the hybrid show that although the overall efficiency of the plant, defined in terms of the energy from both the methane and biomass, is similar to that of the conventional, methane fuelled engine, the efficiency of the conversion of the biomass fuel energy to work output appears to be higher than for other biomass fuelled technologies currently in use. Further, in the ideal limit of a fully renewable biomass fuel, the burning of biomass does not contribute to the net CO 2 emissions, and the CO 2 emission reduction for this second plant can be considerable. Indeed, its implementation on larger internal combustion engine power plants, which have efficiencies of around 45–50%, could result in CO 2 emissions that are as much as

  14. Thermodynamic Investigation of an Integrated Gasification Plant with Solid Oxide Fuel Cell and Steam Cycles

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2012-01-01

    A gasification plant is integrated on the top of a solid oxide fuel cell (SOFC) cycle, while a steam turbine (ST) cycle is used as a bottoming cycle for the SOFC plant. The gasification plant was fueled by woodchips to produce biogas and the SOFC stacks were fired with biogas. The produced gas...... generator (HRSG). The steam cycle was modeled with a simple single pressure level. In addition, a hybrid recuperator was used to recover more energy from the HRSG and send it back to the SOFC cycle. Thus two different configurations were investigated to study the plants characteristic. Such system...

  15. Adoption of nitrogen power conversion system for small scale ultra-long cycle fast reactor eliminating intermediate sodium loop

    International Nuclear Information System (INIS)

    Seo, Seok Bin; Seo, Han; Bang, In Cheol

    2016-01-01

    Highlights: • N 2 power conversion system for both safety and thermal performance aspects. • Sensitivity studies of several controlled parameters on N 2 power conversion system. • The elimination of the intermediate loop increased the cycle thermal efficiency. • The elimination of the intermediate loop expects economic advantages. - Abstract: As one of SFRs, the ultra-long cycle fast reactor with a power rating of 100 MW e (UCFR-100) was introduced for a 60-year operation. As an alternative to the traditional steam Rankine cycle for the power conversion system, gas based Brayton cycle has been considered for UCFR-100. Among Supercritical CO 2 (S-CO 2 ), Helium (He), Nitrogen (N 2 ) as candidates for the power conversion system for UCFR-100, an N 2 power conversion system was chosen considering both safety and thermal performance aspects. The elimination of the intermediate sodium loop could be achieved due to the safety and stable characteristics of nitrogen working fluid. In this paper, sensitivity studies with respect to several controlled parameters on N 2 power conversion system were performed to optimize the system. Furthermore, the elimination of the intermediate loop was evaluated with respect to its impact on the thermodynamic performance and other aspects.

  16. High performance integrated solar combined cycles with minimum modifications to the combined cycle power plant design

    International Nuclear Information System (INIS)

    Manente, Giovanni

    2016-01-01

    Highlights: • Off-design model of a 390 MW_e three pressure combined cycle developed and validated. • The off-design model is used to evaluate different hybridization schemes with solar. • Power boosting and fuel saving with different design modifications are considered. • Maximum solar share of total electricity is only 1% with the existing equipment. • The maximum incremental solar radiation-to-electrical efficiency approaches 29%. - Abstract: The integration of solar energy into natural gas combined cycles has been successfully demonstrated in several integrated solar combined cycles since the beginning of this decade in many countries. There are many motivations that drive investments on integrated solar combined cycles which are primarily the repowering of existing power plants, the compliance with more severe environmental laws on emissions and the mitigation of risks associated with large solar projects. Integrated solar combined cycles are usually developed as brownfield facilities by retrofitting existing natural gas combined cycles and keeping the existing equipment to minimize costs. In this work a detailed off-design model of a 390 MW_e three pressure level natural gas combined cycle is built to evaluate different integration schemes of solar energy which either keep the equipment of the combined cycle unchanged or include new equipment (steam turbine, heat recovery steam generator). Both power boosting and fuel saving operation strategies are analyzed in the search for the highest annual efficiency and solar share. Results show that the maximum incremental power output from solar at design solar irradiance is limited to 19 MW_e without modifications to the existing equipment. Higher values are attainable only including a larger steam turbine. High solar radiation-to-electrical efficiencies in the range 24–29% can be achieved in the integrated solar combined cycle depending on solar share and extension of tube banks in the heat recovery

  17. Conventional and advanced exergetic analyses applied to a combined cycle power plant

    International Nuclear Information System (INIS)

    Petrakopoulou, Fontina; Tsatsaronis, George; Morosuk, Tatiana; Carassai, Anna

    2012-01-01

    Conventional exergy-based methods pinpoint components and processes with high irreversibilities. However, they lack certain insight. For a given advanced technological state, there is a minimum level of exergy destruction related to technological and/or economic constraints that is unavoidable. Furthermore, in any thermodynamic system, exergy destruction stems from both component interactions (exogenous) and component inefficiencies (endogenous). To overcome the limitations of the conventional analyses and to increase our knowledge about a plant, advanced exergy-based analyses have been developed. In this paper, a combined cycle power plant is analyzed using both conventional and advanced exergetic analyses. Except for the expander of the gas turbine system and the high-pressure steam turbine, most of the exergy destruction in the plant components is unavoidable. This unavoidable part is constrained by internal technological limitations, i.e. each component’s endogenous exergy destruction. High levels of endogenous exergy destruction show that component interactions do not contribute significantly to the thermodynamic inefficiencies. In addition, these inefficiencies are unavoidable to a large extent. With the advanced analysis, new improvement strategies are revealed that could not otherwise be found. -- Highlights: ► This is the first application of a complete advanced exergetic analysis to a complex power plant. ► In the three-pressure-level combined cycle power plant studied here, the improvement potential of the majority of the components is low, since most of the exergy destruction is unavoidable. ► Component interactions are generally of lower importance for the considered plant. ► Splitting the exogenous exergy destruction reveals one-to-one component interactions and improvement strategies. ► The advanced exergetic analysis is a necessary supplement to the conventional analysis in improving a complex system.

  18. Fuel cycle strategies for growth of nuclear power in India

    International Nuclear Information System (INIS)

    Purushotham, D.S.C.; Balu, K.

    2002-01-01

    Nuclear power has been identified as an essential component to meet the growing energy demand of India. The three stage fuel cycle strategy to achieve this with the available resources envisages the use of natural uranium in PHWRs in the first stage, the plutonium-uranium/plutonium-thorium cycles in Fast reactors/Advanced HWRs in the second stage, followed by exploitation of essentially U233 in the third stage. The technologies necessary for this programme, mainly through the back-end of the fuel cycle including reprocessing, waste management and recycle of Pu have been developed accordingly, as a direct result of the closed fuel cycle policy followed by us from the very beginning. This paper addresses the considerations involved in several activities taken up in our programme, their current status and plans for the future. (author)

  19. Thermodynamics of Gas Turbine Cycles with Analytic Derivatives in OpenMDAO

    Science.gov (United States)

    Gray, Justin; Chin, Jeffrey; Hearn, Tristan; Hendricks, Eric; Lavelle, Thomas; Martins, Joaquim R. R. A.

    2016-01-01

    A new equilibrium thermodynamics analysis tool was built based on the CEA method using the OpenMDAO framework. The new tool provides forward and adjoint analytic derivatives for use with gradient based optimization algorithms. The new tool was validated against the original CEA code to ensure an accurate analysis and the analytic derivatives were validated against finite-difference approximations. Performance comparisons between analytic and finite difference methods showed a significant speed advantage for the analytic methods. To further test the new analysis tool, a sample optimization was performed to find the optimal air-fuel equivalence ratio, , maximizing combustion temperature for a range of different pressures. Collectively, the results demonstrate the viability of the new tool to serve as the thermodynamic backbone for future work on a full propulsion modeling tool.

  20. Thermodynamic analysis of a combined gas turbine power plant with a solid oxide fuel cell for marine applications

    Directory of Open Access Journals (Sweden)

    Yousri M.A. Welaya

    2013-12-01

    Full Text Available Strong restrictions on emissions from marine power plants (particularly SOx, NOx will probably be adopted in the near future. In this paper, a combined solid oxide fuel cell (SOFC and gas turbine fuelled by natural gas is proposed as an attractive option to limit the environmental impact of the marine sector. It includes a study of a heat-recovery system for 18 MW SOFC fuelled by natural gas, to provide the electric power demand onboard commercial vessels. Feasible heat-recovery systems are investigated, taking into account different operating conditions of the combined system. Two types of SOFC are considered, tubular and planar SOFCs, operated with either natural gas or hydrogen fuels. This paper includes a detailed thermodynamic analysis for the combined system. Mass and energy balances are performed, not only for the whole plant but also for each individual component, in order to evaluate the thermal efficiency of the combined cycle. In addition, the effect of using natural gas as a fuel on the fuel cell voltage and performance is investigated. It is found that a high overall efficiency approaching 70% may be achieved with an optimum configuration using SOFC system under pressure. The hybrid system would also reduce emissions, fuel consumption, and improve the total system efficiency.

  1. Thermodynamic analysis of a combined gas turbine power plant with a solid oxide fuel cell for marine applications

    Science.gov (United States)

    Welaya, Yousri M. A.; Mosleh, M.; Ammar, Nader R.

    2013-12-01

    Strong restrictions on emissions from marine power plants (particularly SOx, NOx) will probably be adopted in the near future. In this paper, a combined solid oxide fuel cell (SOFC) and gas turbine fuelled by natural gas is proposed as an attractive option to limit the environmental impact of the marine sector. It includes a study of a heatrecovery system for 18 MW SOFC fuelled by natural gas, to provide the electric power demand onboard commercial vessels. Feasible heat-recovery systems are investigated, taking into account different operating conditions of the combined system. Two types of SOFC are considered, tubular and planar SOFCs, operated with either natural gas or hydrogen fuels. This paper includes a detailed thermodynamic analysis for the combined system. Mass and energy balances are performed, not only for the whole plant but also for each individual component, in order to evaluate the thermal efficiency of the combined cycle. In addition, the effect of using natural gas as a fuel on the fuel cell voltage and performance is investigated. It is found that a high overall efficiency approaching 70% may be achieved with an optimum configuration using SOFC system under pressure. The hybrid system would also reduce emissions, fuel consumption, and improve the total system efficiency.

  2. Cycle kinetics, steady state thermodynamics and motors-a paradigm for living matter physics

    International Nuclear Information System (INIS)

    Qian, Hong

    2005-01-01

    An integration of the stochastic mathematical models for motor proteins with Hill's steady state thermodynamics yields a rather comprehensive theory for molecular motors as open systems in the nonequilibrium steady state. This theory, a natural extension of Gibbs' approach to isothermal molecular systems in equilibrium, is compared with other existing theories with dissipative structures and dynamics. The theory of molecular motors might be considered as an archetype for studying more complex open biological systems such as biochemical reaction networks inside living cells

  3. Advanced Accelerated Power Cycling Test for Reliability Investigation of Power Device Modules

    DEFF Research Database (Denmark)

    Choi, Uimin; Jørgensen, Søren; Blaabjerg, Frede

    2016-01-01

    This paper presents an apparatus and methodology for an advanced accelerated power cycling test of insulated-gate bipolar transistor (IGBT) modules. In this test, the accelerated power cycling test can be performed under more realistic electrical operating conditions with online wear-out monitoring...... of tested power IGBT module. The various realistic electrical operating conditions close to real three-phase converter applications can be achieved by the simple control method. Further, by the proposed concept of applying the temperature stress, it is possible to apply various magnitudes of temperature...... swing in a short cycle period and to change the temperature cycle period easily. Thanks to a short temperature cycle period, test results can be obtained in a reasonable test time. A detailed explanation of apparatus such as configuration and control methods for the different functions of accelerated...

  4. Numerical optimization of Combined Heat and Power Organic Rankine Cycles – Part A: Design optimization

    International Nuclear Information System (INIS)

    Martelli, Emanuele; Capra, Federico; Consonni, Stefano

    2015-01-01

    This two-part paper proposes an approach based on state-of-the-art numerical optimization methods for simultaneously determining the most profitable design and part-load operation of Combined Heat and Power Organic Rankine Cycles. Compared to the usual design practice, the important advantages of the proposed approach are (i) to consider the part-load performance of the ORC at the design stage, (ii) to optimize not only the cycle variables, but also the main turbine design variables (number of stages, stage loads, rotational speed). In this first part (Part A), the design model and the optimization algorithm are presented and tested on a real-world test case. PGS-COM, a recently proposed hybrid derivative-free algorithm, allows to efficiently tackle the challenging non-smooth black-box problem. - Highlights: • Algorithm for the simultaneous optimization Organic Rakine Cycle and turbine. • Thermodynamic and economic models of boiler, cycle, turbine are developed. • Non-smooth black-box optimization problem is successfully tackled with PGS-COM. • Test cases show that the algorithm returns optimal solutions within 4 min. • Toluene outperforms MDM (a siloxane) in terms of efficiency and costs.

  5. Thermodynamic performance analysis of sequential Carnot cycles using heat sources with finite heat capacity

    International Nuclear Information System (INIS)

    Park, Hansaem; Kim, Min Soo

    2014-01-01

    The maximum efficiency of a heat engine is able to be estimated by using a Carnot cycle. Even though, in terms of efficiency, the Carnot cycle performs the role of reference very well, its application is limited to the case of infinite heat reservoirs, which is not that realistic. Moreover, considering that one of the recent key issues is to produce maximum work from low temperature and finite heat sources, which are called renewable energy sources, more advanced theoretical cycles, which can present a new standard, and the research about them are necessary. Therefore, in this paper, a sequential Carnot cycle, where multiple Carnot cycles are connected in parallel, is studied. The cycle adopts a finite heat source, which has a certain initial temperature and heat capacity, and an infinite heat sink, which is assumed to be ambient air. Heat transfer processes in the cycle occur with the temperature difference between a heat reservoir and a cycle. In order to resolve the heat transfer rate in those processes, the product of an overall heat transfer coefficient and a heat transfer area is introduced. Using these conditions, the performance of a sequential Carnot cycle is analytically calculated. Furthermore, as the efforts for enhancing the work of the cycle, the optimization research is also conducted with numerical calculation. - Highlights: • Modified sequential Carnot cycles are proposed for evaluating low grade heat sources. • Performance of sequential Carnot cycles is calculated analytically. • Optimization study for the cycle is conducted with numerical solver. • Maximum work from a heat source under a certain condition is obtained by equations

  6. Junction temperature estimation for an advanced active power cycling test

    DEFF Research Database (Denmark)

    Choi, Uimin; Blaabjerg, Frede; Jørgensen, S.

    2015-01-01

    estimation method using on-state VCE for an advanced active power cycling test is proposed. The concept of the advanced power cycling test is explained first. Afterwards the junction temperature estimation method using on-state VCE and current is presented. Further, the method to improve the accuracy...... of the maximum junction temperature estimation is also proposed. Finally, the validity and effectiveness of the proposed method is confirmed by experimental results.......On-state collector-emitter voltage (VCE) is a good indicator to determine the wear-out condition of power device modules. Further, it is a one of the Temperature Sensitive Electrical Parameters (TSEPs) and thus can be used for junction temperature estimation. In this paper, the junction temperature...

  7. Advanced power cycling test for power module with on-line on-state VCE measurement

    DEFF Research Database (Denmark)

    Choi, Ui-min; Trintis, Ionut; Blaabjerg, Frede

    2015-01-01

    module. The proposed concept can perform various stress conditions which is valid in a real mission profile and it is using a real power converter application with small loss. The concept of the proposed test setup is first presented. Then, the on-line on-state collector-emitter voltage VCE measurement......Recent research has made an effort to improve the reliability of power electronic systems to comply with more stringent constraints on cost, safety, predicted lifetime and availability in many applications. For this, studies about failure mechanisms of power electronic components and lifetime...... estimation of power semiconductor devices and capacitors have been done. Accelerated power cycling test is one of the common tests to assess the power device module and develop the lifetime model considering the physics of failure. In this paper, a new advanced power cycling test setup is proposed for power...

  8. Sensitivity analysis of system parameters on the performance of the Organic Rankine Cycle system for binary-cycle geothermal power plants

    International Nuclear Information System (INIS)

    Liu, Xiaomin; Wang, Xing; Zhang, Chuhua

    2014-01-01

    The main purpose of this paper is to analyze the sensitivity of system parameters to the performance of the Organic Rankine Cycle (ORC) system quantitatively. A thermodynamic model of the ORC system for binary-cycle geothermal power plants has been developed and verified. The system parameters, such as working fluid, superheat temperature, pinch temperature difference in evaporator and condenser, evaporating temperature, the isentropic efficiencies of the cycle pump and radial inflow turbine are selected as six factors for orthogonal design. The order of factors sensitivity on performance indices of the net power output of the ORC system, the thermal efficiency, the size parameter of radial inflow turbine, the power decrease factor of the pump and the total heat transfer capacity are determined by the range obtained from the orthogonal design. At different geothermal temperatures, the ranges of the six factors corresponding to performance indices are analyzed respectively. The results show that the geothermal temperature influences the range of the factors to the net power output, SP factor of radial inflow turbine, and the total heat transfer capacity, but it has no effect for the range of the factors for the thermal efficiency and the power decrease factor of the pump. The evaporating temperature is always the primary or secondary factor that influence the thermodynamic and economic performance of the ORC system. This study would provide useful references for determining the proper design variables in the performance optimization of the ORC system at different geothermal temperatures. - Highlights: • Evaporating temperature has significant effect on performance of ORC system. • Order of system parameters' sensitivity to the performance of ORC is revealed. • Effect of system parameters on performance indices vary with geothermal temperature. • Geothermal temperature has no effect on range of six factors to the size of turbine

  9. Validity And Reliability Of The Stages Cycling Power Meter.

    Science.gov (United States)

    Granier, Cyril; Hausswirth, Christophe; Dorel, Sylvain; Yann, Le Meur

    2017-09-06

    This study aimed to determine the validity and the reliability of the Stages power meter crank system (Boulder, United States) during several laboratory cycling tasks. Eleven trained participants completed laboratory cycling trials on an indoor cycle fitted with SRM Professional and Stages systems. The trials consisted of an incremental test at 100W, 200W, 300W, 400W and four 7s sprints. The level of pedaling asymmetry was determined for each cycling intensity during a similar protocol completed on a Lode Excalibur Sport ergometer. The reliability of Stages and SRM power meters was compared by repeating the incremental test during a test-retest protocol on a Cyclus 2 ergometer. Over power ranges of 100-1250W the Stages system produced trivial to small differences compared to the SRM (standardized typical error values of 0.06, 0.24 and 0.08 for the incremental, sprint and combined trials, respectively). A large correlation was reported between the difference in power output (PO) between the two systems and the level of pedaling asymmetry (r=0.58, p system according to the level of pedaling asymmetry provided only marginal improvements in PO measures. The reliability of the Stages power meter at the sub-maximal intensities was similar to the SRM Professional model (coefficient of variation: 2.1 and 1.3% for Stages and SRM, respectively). The Stages system is a suitable device for PO measurements, except when a typical error of measurement power ranges of 100-1250W is expected.

  10. Overall performance assessment of a combined cycle power plant: An exergo-economic analysis

    International Nuclear Information System (INIS)

    Sahin, Ahmet Z.; Al-Sharafi, Abdullah; Yilbas, Bekir S.; Khaliq, Abdul

    2016-01-01

    Highlights: • An exergo-economic analysis is carried out for a combined cycle power plant. • An overall performance index (OPI) is defined to analyze the power plant. • Four performance indicators and three scenarios are considered in the analysis. • The optimum configuration of the power plant differs for each scenarios considered. - Abstract: An exergo-economic analysis is carried out for a combined cycle power plant using the first law and the second law of thermodynamics, and the economic principles while incorporating GT PRO/PEACE Software Packages. An overall performance index (OPI) is defined to assess and analyze the optimum operational and design configurations of the power plant. Four performance indicators are considered for the analysis; namely, energy efficiency (ENE), exergy efficiency (EXE), levelized cost of electricity (COE), and the total investment (TI) cost. Three possible scenarios are considered in which different weight factor is assigned to the performance indicators when assessing the performance. These scenarios are: (i) the conventional case in which the levelized cost of electricity is given a high priority, (ii) environmental conscious case in which the exergy efficiency is given a high priority, and (iii) the economical case in which the total cost of investment is given a high priority. It is shown that the optimum size and the configuration of the power plant differ for each scenarios considered. The selection and optimization of the size and configuration of the power plant are found to be depending on the user priorities and the weight factors assigned to the performance indicators.

  11. Combined Turbine and Cycle Optimization for Organic Rankine Cycle Power Systems—Part B

    DEFF Research Database (Denmark)

    La Seta, Angelo; Meroni, Andrea; Andreasen, Jesper Graa

    2016-01-01

    Organic Rankine cycle (ORC) power systems have recently emerged as promising solutions for waste heat recovery in low- and medium-size power plants. Their performance and economic feasibility strongly depend on the expander. The design process and efficiency estimation are particularly challenging...... due to the peculiar physical properties of the working fluid and the gas-dynamic phenomena occurring in the machine. Unlike steam Rankine and Brayton engines, organic Rankine cycle expanders combine small enthalpy drops with large expansion ratios. These features yield turbine designs with few highly...... is the preliminary design of an organic Rankine cycle turbogenerator to increase the overall energy efficiency of an offshore platform. For an increase in expander pressure ratio from 10 to 35, the results indicate up to 10% point reduction in expander performance. This corresponds to a relative reduction in net...

  12. Off-design performance analysis of a solar-powered organic Rankine cycle

    International Nuclear Information System (INIS)

    Wang, Jiangfeng; Yan, Zhequan; Zhao, Pan; Dai, Yiping

    2014-01-01

    Highlights: • Solar-powered organic Rankine cycle with CPC and thermal storage unit is studied. • Off-design performances encountering the changes of key parameters are examined. • Off-design performance is analyzed over a whole day and in different months. - Abstract: Performance evaluation of a thermodynamic system under off-design conditions is very important for reliable and cost-effective operation. In this study, an off-design model of an organic Rankine cycle driven by solar energy is established with compound parabolic collector (CPC) to collect the solar radiation and thermal storage unit to achieve the continuous operation of the overall system. The system off-design behavior is examined under the change in environment temperature, as well as thermal oil mass flow rates of vapor generator and CPC. In addition, the off-design performance of the system is analyzed over a whole day and in different months. The results indicate that a decrease in environment temperature, or the increases in thermal oil mass flow rates of vapor generator and CPC could improve the off-design performance. The system obtains the maximum average exergy efficiency in December and the maximum net power output in June or in September. Both the net power output and the average exergy efficiency reach minimum values in August

  13. Thermoeconomic optimization of a combined-cycle solar tower power plant

    International Nuclear Information System (INIS)

    Spelling, James; Favrat, Daniel; Martin, Andrew; Augsburger, Germain

    2012-01-01

    A dynamic model of a pure-solar combined-cycle power plant has been developed in order to allow determination of the thermodynamic and economic performance of the plant for a variety of operating conditions and superstructure layouts. The model was then used for multi-objective thermoeconomic optimization of both the power plant performance and cost, using a population-based evolutionary algorithm. In order to examine the trade-offs that must be made, two conflicting objectives will be considered, namely minimal investment costs and minimal levelized electricity costs. It was shown that efficiencies in the region of 18–24% can be achieved, and this for levelized electricity costs in the region of 12–24 UScts/kWh e , depending on the magnitude of the initial investment, making the system competitive with current solar thermal technology. -- Highlights: ► Pure-solar combined-cycle studied using thermoeconomic tools. ► Multi-objective optimization conducted to determine Pareto-optimal power plant designs. ► Levelised costs between 12 and 24 UScts/kWhe predicted. ► Efficiencies between 18 and 24% predicted.

  14. Modelling and optimization of combined cycle power plant based on exergoeconomic and environmental analyses

    International Nuclear Information System (INIS)

    Ganjehkaviri, A.; Mohd Jaafar, M.N.; Ahmadi, P.; Barzegaravval, H.

    2014-01-01

    This research paper presents a study on a comprehensive thermodynamic modelling of a combined cycle power plant (CCPP). The effects of economic strategies and design parameters on the plant optimization are also studied. Exergoeconomic analysis is conducted in order to determine the cost of electricity and cost of exergy destruction. In addition, a comprehensive optimization study is performed to determine the optimal design parameters of the power plant. Next, the effects of economic parameters variations on the sustainability, carbon dioxide emission and fuel consumption of the plant are investigated and are presented for a typical combined cycle power plant. Therefore, the changes in economic parameters caused the balance between cash flows and fix costs of the plant changes at optimum point. Moreover, economic strategies greatly limited the maximum reasonable carbon emission and fuel consumption reduction. The results showed that by using the optimum values, the exergy efficiency increases for about 6%, while CO 2 emission decreases by 5.63%. However, the variation in the cost was less than 1% due to the fact that a cost constraint was implemented. In addition, the sensitivity analysis for the optimization study was curtailed to be carried out; therefore, the optimization process and results to two important parameters are presented and discussed.

  15. Thermal performance of a modified ammonia–water power cycle for reclaiming mid/low-grade waste heat

    International Nuclear Information System (INIS)

    Junye, Hua; Yaping, Chen; Jiafeng, Wu

    2014-01-01

    Highlights: • A modified Kalina cycle is proposed for power and heat cogeneration from mid/low-grade waste heat. • A water-cooling solution cooler is set for cogeneration of sanitary or heating hot water. • Work concentration is determined for suitable turbine inlet pressure and positive back pressure. • Basic concentration should match work concentration for higher efficiency. • Sanitary water with 50.7 °C and capacity of a quarter of total reclaimed heat load is cogenerated. - Abstract: A modified Kalina cycle was simulated, which is a triple-pressure ammonia–water power cycle adding a preheater and a water-cooling solution cooler to the original loop. The cycle acquires higher power recovery efficiency by realizing proper internal recuperation and suitable temperature-difference in phase change processes to match both heat source and cooling water. The influences of some key parameters on the thermodynamic performance of the cycle were discussed, including the work and basic concentrations of solution, circulation multiple and the turbine inlet temperature. It is shown that the basic concentration should match the work concentration for higher efficiency. Although higher work concentration could be slightly beneficial to cycle efficiency, the work concentration is mainly determined by considering the suitable turbine inlet/back pressure. Besides, this cycle can be used as a cogeneration system of power and sanitary or heating hot water. The calculation example presented finally with the turbine inlet parameters of 300 °C/6 MPa and the cycle lowest temperature of 30 °C shows that the power recovery efficiency reaches 15.87%, which is about 16.6% higher than that of the steam Rankine cycle. And it also provides 50.7 °C sanitary water with about a quarter of the total heating load reclaimed

  16. Performance evaluation of an irreversible Miller cycle comparing FTT (finite-time thermodynamics) analysis and ANN (artificial neural network) prediction

    International Nuclear Information System (INIS)

    Mousapour, Ashkan; Hajipour, Alireza; Rashidi, Mohammad Mehdi; Freidoonimehr, Navid

    2016-01-01

    In this paper, the first and second-laws efficiencies are applied to performance analysis of an irreversible Miller cycle. In the irreversible cycle, the linear relation between the specific heat of the working fluid and its temperature, the internal irreversibility described using the compression and expansion efficiencies, the friction loss computed according to the mean velocity of the piston and the heat-transfer loss are considered. The effects of various design parameters, such as the minimum and maximum temperatures of the working fluid and the compression ratio on the power output and the first and second-laws efficiencies of the cycle are discussed. In the following, a procedure named ANN is used for predicting the thermal efficiency values versus the compression ratio, and the minimum and maximum temperatures of the Miller cycle. Nowadays, Miller cycle is widely used in the automotive industry and the obtained results of this study will provide some significant theoretical grounds for the design optimization of the Miller cycle. - Highlights: • The performance of an irreversible Miller cycle is investigated using FFT. • The effects of design parameters on the performance of the cycle are investigated. • ANN is applied to predict the thermal efficiency and the power output values. • There is an excellent correlation between FTT and ANN data. • ANN can be applied to predict data where FTT analysis has not been performed.

  17. Modeling of the vapor cycle of Laguna Verde with the PEPSE code to conditions of thermal power licensed at present (2027 MWt)

    International Nuclear Information System (INIS)

    Castaneda G, M. A.; Maya G, F.; Medel C, J. E.; Cardenas J, J. B.; Cruz B, H. J.; Mercado V, J. J.

    2011-11-01

    By means of the use of the performance evaluation of power system efficiencies (PEPSE) code was modeled the vapor cycle of the nuclear power station of Laguna Verde to reproduce the nuclear plant behavior to conditions of thermal power, licensed at present (2027 MWt); with the purpose of having a base line before the implementation of the project of extended power increase. The model of the gauged vapor cycle to reproduce the nuclear plant conditions makes use of the PEPSE model, design case of the vapor cycle of nuclear power station of Laguna Verde, which has as main components of the model the great equipment of the vapor cycle of Laguna Verde. The design case model makes use of information about the design requirements of each equipment for theoretically calculating the electric power of exit, besides thermodynamic conditions of the vapor cycle in different points. Starting from the design model and making use of data of the vapor cycle measured in the nuclear plant; the adjustment factors were calculated for the different equipment s of the vapor cycle, to reproduce with the PEPSE model the real vapor cycle of Laguna Verde. Once characterized the model of the vapor cycle of Laguna Verde, we can realize different sensibility studies to determine the effects macros to the vapor cycle by the variation of certain key parameters. (Author)

  18. Modeling of Turbine Cycles Using a Neuro-Fuzzy Based Approach to Predict Turbine-Generator Output for Nuclear Power Plants

    Directory of Open Access Journals (Sweden)

    Yea-Kuang Chan

    2012-01-01

    Full Text Available Due to the very complex sets of component systems, interrelated thermodynamic processes and seasonal change in operating conditions, it is relatively difficult to find an accurate model for turbine cycle of nuclear power plants (NPPs. This paper deals with the modeling of turbine cycles to predict turbine-generator output using an adaptive neuro-fuzzy inference system (ANFIS for Unit 1 of the Kuosheng NPP in Taiwan. Plant operation data obtained from Kuosheng NPP between 2006 and 2011 were verified using a linear regression model with a 95% confidence interval. The key parameters of turbine cycle, including turbine throttle pressure, condenser backpressure, feedwater flow rate and final feedwater temperature are selected as inputs for the ANFIS based turbine cycle model. In addition, a thermodynamic turbine cycle model was developed using the commercial software PEPSE® to compare the performance of the ANFIS based turbine cycle model. The results show that the proposed ANFIS based turbine cycle model is capable of accurately estimating turbine-generator output and providing more reliable results than the PEPSE® based turbine cycle models. Moreover, test results show that the ANFIS performed better than the artificial neural network (ANN, which has also being tried to model the turbine cycle. The effectiveness of the proposed neuro-fuzzy based turbine cycle model was demonstrated using the actual operating data of Kuosheng NPP. Furthermore, the results also provide an alternative approach to evaluate the thermal performance of nuclear power plants.

  19. Design and Modelling of Small Scale Low Temperature Power Cycles

    DEFF Research Database (Denmark)

    Wronski, Jorrit

    he work presented in this report contributes to the state of the art within design and modelling of small scale low temperature power cycles. The study is divided into three main parts: (i) fluid property evaluation, (ii) expansion device investigations and (iii) heat exchanger performance......-oriented Modelica code and was included in the thermo Cycle framework for small scale ORC systems. Special attention was paid to the valve system and a control method for variable expansion ratios was introduced based on a cogeneration scenario. Admission control based on evaporator and condenser conditions...

  20. Thermodynamic analysis of high-temperature regenerative organic Rankine cycles using siloxanes as working fluids

    International Nuclear Information System (INIS)

    Fernandez, F.J.; Prieto, M.M.; Suarez, I.

    2011-01-01

    A recent novel adjustment of the Span-Wagner equation of state for siloxanes, used as working fluids in high-temperature organic Rankine cycles, is applied in a mathematical model to solve cycles under several working conditions. The proposed scheme includes a thermo-oil intermediate heat circuit between the heat source and the organic Rankine cycle. Linear and cyclic siloxanes are assayed in saturated, superheated and supercritical cycles. The cycle includes an internal heat exchanger (regenerative cycle), although a non-regenerative scheme is also solved. In the first part of the study, a current of combustion gases cooled to close to their dew point temperature is taken as the reference heat source. In the second part, the outlet temperature of the heat source is varied over a wide range, determining appropriate fluids and schemes for each thermal level. Simple linear (MM, MDM) siloxanes in saturated regenerative schemes show good efficiencies and ensure thermal stability of the working fluid. -- Highlights: → Organic Rankine cycles with polymethylsiloxanes as working fluids were modelled. → The cycle scheme is regenerative and includes an intermediate heat transfer fluid. → The fluid properties were calculated by means of the Span-Wagner equation of state. → Vapour conditions to the expander and source thermal level were analysed. → Siloxanes MM, MDM and D 4 under saturated conditions were the best options.

  1. Energy Conversion Advanced Heat Transport Loop and Power Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Oh, C. H.

    2006-08-01

    The Department of Energy and the Idaho National Laboratory are developing a Next Generation Nuclear Plant (NGNP) to serve as a demonstration of state-of-the-art nuclear technology. The purpose of the demonstration is two fold 1) efficient low cost energy generation and 2) hydrogen production. Although a next generation plant could be developed as a single-purpose facility, early designs are expected to be dual-purpose. While hydrogen production and advanced energy cycles are still in its early stages of development, research towards coupling a high temperature reactor, electrical generation and hydrogen production is under way. Many aspects of the NGNP must be researched and developed in order to make recommendations on the final design of the plant. Parameters such as working conditions, cycle components, working fluids, and power conversion unit configurations must be understood. Three configurations of the power conversion unit were demonstrated in this study. A three-shaft design with 3 turbines and 4 compressors, a combined cycle with a Brayton top cycle and a Rankine bottoming cycle, and a reheated cycle with 3 stages of reheat were investigated. An intermediate heat transport loop for transporting process heat to a High Temperature Steam Electrolysis (HTSE) hydrogen production plant was used. Helium, CO2, and an 80% nitrogen, 20% helium mixture (by weight) were studied to determine the best working fluid in terms cycle efficiency and development cost. In each of these configurations the relative component size were estimated for the different working fluids. The relative size of the turbomachinery was measured by comparing the power input/output of the component. For heat exchangers the volume was computed and compared. Parametric studies away from the baseline values of the three-shaft and combined cycles were performed to determine the effect of varying conditions in the cycle. This gives some insight into the sensitivity of these cycles to various

  2. Transcritical CO2 power cycle – Effects of regenerative heating using turbine bleed gas at intermediate pressure

    International Nuclear Information System (INIS)

    Mondal, Subha; De, Sudipta

    2015-01-01

    For energy utilization from low temperature waste heat, CO 2 is a potential working fluid due to its lower critical temperature. In this work, assuming finite quantity of flue gas available at low temperature (200 °C), a thermodynamic model is developed for a transcritical CO 2 power cycle utilizing turbine bleed gas for regenerative heating. Analysis show that the cycle performance improves with higher value of bleed ratio. However, for a specified bleed pressure and bleed gas temperature at the regenerator exit, maximum practical value of bleed ratio may be fixed by considering the exponential growth of the regenerator size (specified by NTU (number of transfer unit)). Most significant observation is the existence of optimum bleed pressures corresponding to maximum 1st law efficiency or minimum cycle irreversibility for specified values of remaining cycle parameters. - Highlights: • Thermodynamic model for Transcritical CO 2 cycle with bleed gas are developed. • Effects of bleed ratio, pressure, and regenerator exit gas temperature are studied. • 1st and 2nd law efficiencies are estimated. • An optimum bleed pressure for maximum 1st and 2nd efficiencies is obtained. • Maximum value of 1st law efficiency is limited by regenerator size

  3. Thermodynamic investigation of an integrated gasification plant with solid oxide fuel cell and steam cycles

    Energy Technology Data Exchange (ETDEWEB)

    Rokni, Masoud [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Mechanical Engineering, Thermal Energy System

    2012-07-01

    A gasification plant is integrated on the top of a solid oxide fuel cell (SOFC) cycle, while a steam turbine (ST) cycle is used as a bottoming cycle for the SOFC plant. The gasification plant was fueled by woodchips to produce biogas and the SOFC stacks were fired with biogas. The produced gas was rather clean for feeding to the SOFC stacks after a simple cleaning step. Because all the fuel cannot be burned in the SOFC stacks, a burner was used to combust the remaining fuel. The off-gases from the burner were then used to produce steam for the bottoming steam cycle in a heat recovery steam generator (HRSG). The steam cycle was modeled with a simple single pressure level. In addition, a hybrid recuperator was used to recover more energy from the HRSG and send it back to the SOFC cycle. Thus two different configurations were investigated to study the plants characteristic. Such system integration configurations are completely novel and have not been studied elsewhere. Plant efficiencies of 56% were achieved under normal operation which was considerably higher than the IGCC (Integrated Gasification Combined Cycle) in which a gasification plant is integrated with a gas turbine and a steam turbine. Furthermore, it is shown that under certain operating conditions, plant efficiency of about 62 is also possible to achieve. (orig.)

  4. Thermodynamic properties calculation of the flue gas based on its composition estimation for coal-fired power plants

    International Nuclear Information System (INIS)

    Xu, Liang; Yuan, Jingqi

    2015-01-01

    Thermodynamic properties of the working fluid and the flue gas play an important role in the thermodynamic calculation for the boiler design and the operational optimization in power plants. In this study, a generic approach to online calculate the thermodynamic properties of the flue gas is proposed based on its composition estimation. It covers the full operation scope of the flue gas, including the two-phase state when the temperature becomes lower than the dew point. The composition of the flue gas is online estimated based on the routinely offline assays of the coal samples and the online measured oxygen mole fraction in the flue gas. The relative error of the proposed approach is found less than 1% when the standard data set of the dry and humid air and the typical flue gas is used for validation. Also, the sensitivity analysis of the individual component and the influence of the measurement error of the oxygen mole fraction on the thermodynamic properties of the flue gas are presented. - Highlights: • Flue gas thermodynamic properties in coal-fired power plants are online calculated. • Flue gas composition is online estimated using the measured oxygen mole fraction. • The proposed approach covers full operation scope, including two-phase flue gas. • Component sensitivity to the thermodynamic properties of flue gas is presented.

  5. Supercritical Water Reactor Cycle for Medium Power Applications

    International Nuclear Information System (INIS)

    BD Middleton; J Buongiorno

    2007-01-01

    Scoping studies for a power conversion system based on a direct-cycle supercritical water reactor have been conducted. The electric power range of interest is 5-30 MWe with a design point of 20 MWe. The overall design objective is to develop a system that has minimized physical size and performs satisfactorily over a broad range of operating conditions. The design constraints are as follows: Net cycle thermal efficiency (ge)20%; Steam turbine outlet quality (ge)90%; and Pumping power (le)2500 kW (at nominal conditions). Three basic cycle configurations were analyzed. Listed in order of increased plant complexity, they are: (1) Simple supercritical Rankine cycle; (2) All-supercritical Brayton cycle; and (3) Supercritical Rankine cycle with feedwater preheating. The sensitivity of these three configurations to various parameters, such as reactor exit temperature, reactor pressure, condenser pressure, etc., was assessed. The Thermoflex software package was used for this task. The results are as follows: (a) The simple supercritical Rankine cycle offers the greatest hardware simplification, but its high reactor temperature rise and reactor outlet temperature may pose serious problems from the viewpoint of thermal stresses, stability and materials in the core. (b) The all-supercritical Brayton cycle is not a contender, due to its poor thermal efficiency. (c) The supercritical Rankine cycle with feedwater preheating affords acceptable thermal efficiency with lower reactor temperature rise and outlet temperature. (d) The use of a moisture separator improves the performance of the supercritical Rankine cycle with feedwater preheating and allows for a further reduction of the reactor outlet temperature, thus it was selected for the next step. Preliminary engineering design of the supercritical Rankine cycle with feedwater preheating and moisture separation was performed. All major components including the turbine, feedwater heater, feedwater pump, condenser, condenser pump

  6. Life Cycle Assessment of Coal-fired Power Production

    Energy Technology Data Exchange (ETDEWEB)

    Spath, P. L.; Mann, M. K.; Kerr, D. R.

    1999-09-01

    Coal has the largest share of utility power generation in the US, accounting for approximately 56% of all utility-produced electricity (US DOE, 1998). Therefore, understanding the environmental implications of producing electricity from coal is an important component of any plan to reduce total emissions and resource consumption. A life cycle assessment (LCA) on the production of electricity from coal was performed in order to examine the environmental aspects of current and future pulverized coal boiler systems. Three systems were examined: (1) a plant that represents the average emissions and efficiency of currently operating coal-fired power plants in the US (this tells us about the status quo), (2) a new coal-fired power plant that meets the New Source Performance Standards (NSPS), and (3) a highly advanced coal-fired power plant utilizing a low emission boiler system (LEBS).

  7. Effect of cycle coupling-configuration on energy cascade utilization for a new power and cooling cogeneration cycle

    International Nuclear Information System (INIS)

    Jing, Xuye; Zheng, Danxing

    2014-01-01

    Highlights: • A new power and cooling cogeneration cycle was proposed. • The thermophysical properties and the performance of the new cycle were calculated. • Different cycle coupling-configurations were analyzed. • The energy efficiency boosting mechanism of the new cycle was elucidated. - Abstract: To recover mid-low grade heat, a new power/cooling cogeneration cycle was proposed by combining the Kalina cycle and the double-effect ammonia–water absorption refrigeration (DAAR) cycle together, and the equivalent heat-to-power and exergy efficiencies of the cogeneration cycle reached 41.18% and 58.00%, respectively. To determine the effect of cycle coupling-configuration on energy cascade utilization for the new cycle, the cycle coupling-configuration of the Kalina and DAAR cycles were first analyzed, after which the cycle coupling-configuration of the new cycle was analyzed. Analysis results showed that the cycle coupling-configuration of the new cycle enhanced the energy cascade utilization. Furthermore, the energy efficiency boosting mechanism of the new cycle was elucidated

  8. Thermodynamic constitutive model for load-biased thermal cycling test of shape memory alloy

    International Nuclear Information System (INIS)

    Young, Sung; Nam, Tae-Hyun

    2013-01-01

    Graphical abstract: - Highlights: • Thermodynamic calculation model for martensitic transformation of shape memory alloy was proposed. • Evolution of the self-accommodation was considered independently by a rate-dependent kinetic equation. • Finite element calculation was conducted for B2–B19′ transformation of Ti–44.5Ni–5Cu–0.5 V (at.%). • Three-dimensional numerical results predict the macroscopic strain under bias loading accurately. - Abstract: This paper presents a three-dimensional calculation model for martensitic phase transformation of shape memory alloy. Constitutive model based on thermodynamic theory was provided. The average behavior was accounted for by considering the volume fraction of each martensitic variant in the material. Evolution of the volume fraction of each variant was determined by a rate-dependent kinetic equation. We assumed that nucleation rate is faster for the self-accommodation than for the stress-induced variants. Three-dimensional finite element analysis was conducted and the results were compared with the experimental data of Ti–44.5Ni–5Cu–0.5 V (at.%) alloy under bias loading

  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. 'Crud' detection and evaluation during the Embalse nuclear power plant's thermal cycle for powers of 100%

    International Nuclear Information System (INIS)

    Fernandez, A.; Rosales, A.H.; Mura, V.R.; Sentupery, C.; Rascon, H.

    1987-01-01

    This paper describes the 'crud' measurements performed during the Embalse nuclear power plant's thermal cycle for a power of 100% (645 MWe) under different purification conditions. The aim of this work is to optimize the four steam generators' tube plate cleaning in function of the sweeping produced by their purification. (Author)

  11. Life cycle assessment of a biomass gasification combined-cycle power system

    Energy Technology Data Exchange (ETDEWEB)

    Mann, M.K.; Spath, P.L.

    1997-12-01

    The potential environmental benefits from biomass power are numerous. However, biomass power may also have some negative effects on the environment. Although the environmental benefits and drawbacks of biomass power have been debated for some time, the total significance has not been assessed. This study serves to answer some of the questions most often raised in regard to biomass power: What are the net CO{sub 2} emissions? What is the energy balance of the integrated system? Which substances are emitted at the highest rates? What parts of the system are responsible for these emissions? To provide answers to these questions, a life cycle assessment (LCA) of a hypothetical biomass power plant located in the Midwest United States was performed. LCA is an analytical tool for quantifying the emissions, resource consumption, and energy use, collectively known as environmental stressors, that are associated with converting a raw material to a final product. Performed in conjunction with a technoeconomic feasibility study, the total economic and environmental benefits and drawbacks of a process can be quantified. This study complements a technoeconomic analysis of the same process, reported in Craig and Mann (1996) and updated here. The process studied is based on the concept of power Generation in a biomass integrated gasification combined cycle (BIGCC) plant. Broadly speaking, the overall system consists of biomass production, its transportation to the power plant, electricity generation, and any upstream processes required for system operation. The biomass is assumed to be supplied to the plant as wood chips from a biomass plantation, which would produce energy crops in a manner similar to the way food and fiber crops are produced today. Transportation of the biomass and other materials is by both rail and truck. The IGCC plant is sized at 113 MW, and integrates an indirectly-heated gasifier with an industrial gas turbine and steam cycle. 63 refs., 34 figs., 32 tabs.

  12. Life cycle assessment of a biomass gasification combined-cycle power system

    Energy Technology Data Exchange (ETDEWEB)

    Mann, M.K.; Spath, P.L.

    1997-12-01

    The potential environmental benefits from biomass power are numerous. However, biomass power may also have some negative effects on the environment. Although the environmental benefits and drawbacks of biomass power have been debated for some time, the total significance has not been assessed. This study serves to answer some of the questions most often raised in regard to biomass power: What are the net CO{sub 2} emissions? What is the energy balance of the integrated system? Which substances are emitted at the highest rates? What parts of the system are responsible for these emissions? To provide answers to these questions, a life cycle assessment (LCA) of a hypothetical biomass power plant located in the Midwest United States was performed. LCA is an analytical tool for quantifying the emissions, resource consumption, and energy use, collectively known as environmental stressors, that are associated with converting a raw material to a final product. Performed in conjunction with a t echnoeconomic feasibility study, the total economic and environmental benefits and drawbacks of a process can be quantified. This study complements a technoeconomic analysis of the same process, reported in Craig and Mann (1996) and updated here. The process studied is based on the concept of power Generation in a biomass integrated gasification combined cycle (BIGCC) plant. Broadly speaking, the overall system consists of biomass production, its transportation to the power plant, electricity generation, and any upstream processes required for system operation. The biomass is assumed to be supplied to the plant as wood chips from a biomass plantation, which would produce energy crops in a manner similar to the way food and fiber crops are produced today. Transportation of the biomass and other materials is by both rail and truck. The IGCC plant is sized at 113 MW, and integrates an indirectly-heated gasifier with an industrial gas turbine and steam cycle. 63 refs., 34 figs., 32 tabs.

  13. Thermodynamics of charged rotating dilaton black branes with power-law Maxwell field

    International Nuclear Information System (INIS)

    Zangeneh, M.K.; Sheykhi, A.; Dehghani, M.H.

    2015-01-01

    In this paper, we construct a new class of charged rotating dilaton black brane solutions, with a complete set of rotation parameters, which is coupled to a nonlinear Maxwell field. The Lagrangian of the matter field has the form of the power-law Maxwell field. We study the causal structure of the spacetime and its physical properties in ample details. We also compute thermodynamic and conserved quantities of the spacetime, such as the temperature, entropy, mass, charge, and angular momentum. We find a Smarr-formula for the mass and verify the validity of the first law of thermodynamics on the black brane horizon. Finally, we investigate the thermal stability of solutions in both the canonical and the grand-canonical ensembles and disclose the effects of dilaton field and nonlinearity of the Maxwell field on the thermal stability of the solutions. We find that, for α ≤ 1, charged rotating black brane solutions are thermally stable independent of the values of the other parameters. For α > 1, the solutions can encounter an unstable phase depending on the metric parameters. (orig.)

  14. Power cycling experiments in INR-TRIGA-SSR Reactor

    International Nuclear Information System (INIS)

    Dumitru, M.

    2008-01-01

    The in-reactor experimental program started this summer with some power cycling experiments to provide date on fuel behaviour under abnormal reactor operating conditions. The paper describes the irradiation device, its operational features and an original 'under-flux' movement system. Also, there are presented main data of irradiation device (pressure, flow, temperature, construction), in-pile section, location, sample, instrumentation, experimental sequences and operating data of Interest for the experimenters. (author)

  15. Closed Brayton Cycle Power Conversion Unit for Fission Surface Power Phase I Final Report

    Science.gov (United States)

    Fuller, Robert L.

    2010-01-01

    A Closed Brayton cycle power conversion system has been developed to support the NASA fission surface power program. The goal is to provide electricity from a small nuclear reactor heat source for surface power production for lunar and Mars environments. The selected media for a heat source is NaK 78 with water as a cooling source. The closed Brayton cycle power was selected to be 12 kWe output from the generator terminals. A heat source NaK temperature of 850 K plus or minus 25 K was selected. The cold source water was selected at 375 K plus or minus 25 K. A vacuum radiation environment of 200 K is specified for environmental operation. The major components of the system are the power converter, the power controller, and the top level data acquisition and control unit. The power converter with associated sensors resides in the vacuum radiation environment. The power controller and data acquisition system reside in an ambient laboratory environment. Signals and power are supplied across the pressure boundary electrically with hermetic connectors installed on the vacuum vessel. System level analyses were performed on working fluids, cycle design parameters, heater and cooling temperatures, and heat exchanger options that best meet the needs of the power converter specification. The goal is to provide a cost effective system that has high thermal-to-electric efficiency in a compact, lightweight package.

  16. Thermodynamic evaluation of the Kalina split-cycle concepts for waste heat recovery applications

    DEFF Research Database (Denmark)

    Nguyen, Tuong-Van; Knudsen, Thomas; Larsen, Ulrik

    2014-01-01

    of varying boundary conditions by conducting an exergy analysis. The design parameters of each configuration were determined by performing a multi-variable optimisation. The results indicate that the Kalina split-cycle with reheat presents an exergetic efficiency by 2.8% points higher than a reference Kalina...... and condenser, and indicates a reduction of the exergy destruction by about 23% in the heat recovery system compared to the baseline cycle....

  17. Thermodynamic evaluation of a novel solar-biomass hybrid power generation system

    International Nuclear Information System (INIS)

    Bai, Zhang; Liu, Qibin; Lei, Jing; Wang, Xiaohe; Sun, Jie; Jin, Hongguang

    2017-01-01

    Highlights: • A solar-biomass hybrid power system with zero carbon dioxide emission is proposed. • The internal mechanisms of the solar-biomass utilization are discussed. • The on-design and off-design properties of the system are numerically investigated. • The configurations of the proposed system are optimized. - Abstract: A solar-biomass hybrid power generation system, which integrates a solar thermal energy collection subsystem, a biomass steam boiler and a steam turbine power generation block, is developed for efficiently utilizing renewable energies. The solar thermal energy is concentrated by parabolic trough collectors and is used to heat the feed-water to the superheated steam of 371 °C, then the generated solar steam is further heated to a higher temperature level of 540 °C via a second-stage heating process in a biomass boiler, the system power generation capacity is about 50 MW. The hybrid process of the solar energy and biomass contributes to ameliorating the system thermodynamic performances and reducing of the exergy loss within the steam generation process. The off-design evaluation results indicate that the annual net solar-to-electric efficiency of the hybrid power system is improved to 18.13%, which is higher than that of the typical parabolic trough solar power system as 15.79%. The levelized cost of energy drops to 0.077 $/(kW h) from 0.192 $/(kW h). The annual biomass consumption rate is reduced by 22.53% in comparison with typical biomass power systems. The research findings provide a promising approach for the efficient utilization of the abundant renewable energies resources and the reduction of carbon dioxide emission.

  18. Thermodynamic modeling of a gas micro turbine power system; Modelagem termodinamica de uma microturbina a gas

    Energy Technology Data Exchange (ETDEWEB)

    Venson, Giuliano Gardolinski [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Mecanica], e-mail: venson@ufmg.br; Barros, Jose Eduardo Mautone; Pereira, Josemar Figueiredo [Centro Federal de Educacao Tecnologica de Minas Gerais (CEFET-MG), Belo Horizonte, MG (Brazil)], e-mail: mautone@des.cefetmg.br, e-mail: josemar_cefet@yahoo.com.br

    2006-07-01

    This work presents the modeling of a gas microturbine power generator. The microturbine consists in a small thermo-electrical power unit, design for combined heat and power generation. The unit has an electric generator, coaxially connected with a turbocharger, which one is driven by a fuel burner. The system also incorporates an air regenerator, used for pre-heat the combustion air, and a heat exchanger, used for water heating. The objective of the modeling is the attainment of the electrical performance and the operational limits for the microturbine in function of the subsystems operational conditions. The modeling is based on the first law of the thermodynamic, using specific models for each component. In the combustion chamber is used a model that takes the fuel injection properties, as absolute pressure and temperature. A semi-empirical model, based in the modified Euler equation, is used in the turbocharger. In the air regenerator and heat exchanger, the method of mean logarithmic temperature difference is used. Through the modeling of a commercial microturbine, reference values obtained were used in some subsystems of a new microturbine. The results for this new microturbine in development, based in automotive turbochargers, indicate a nominal electrical power of 38 kW with electrical efficiency of 33% and global efficiency of 73%. (author)

  19. Reverse engineering of fluid selection for thermodynamic cycles with cubic equations of state, using a compression heat pump as example

    International Nuclear Information System (INIS)

    Roskosch, Dennis; Atakan, Burak

    2015-01-01

    Fluid selection for thermodynamic cycles like refrigeration cycles, heat pumps or organic Rankine cycles remains an actual topic. Generally the search for a working fluid is based on experimental approaches or on a not very systematic trial and error approach, far from being elegant. An alternative method may be a theory based reverse engineering approach, proposed and investigated here: The design process should start with an optimal process and with (abstract) properties of the fluid needed to fit into this optimal process, best described by some general equation of state and the corresponding fluid-describing parameters. These should be analyzed and optimized with respect to the defined model process, which also has to be optimized simultaneously. From this information real fluids can be selected or even synthesized which have fluid defining properties in the optimum regime like critical temperature or ideal gas capacities of heat, allowing to find new working fluids, not considered so far. The number and kind of the fluid-defining parameters is mainly based on the choice of the used EOS (equation of state). The property model used in the present work is based on the cubic Peng–Robinson equation, chosen due to its moderate numerical expense, sufficient accuracy as well as a general availability of the fluid-defining parameters for many compounds. The considered model-process works between the temperature levels of 273.15 and 333.15 K and can be used as heat pump for supplying buildings with heat, typically. The objective functions are the COP (coefficient of performance) and the VHC (volumetric heating capacity) as a function of critical pressure, critical temperature, acentric factor and two coefficients for the temperature-dependent isobaric ideal gas heat capacity. Also, the steam quality at the compressor entrance has to be regarded as a problem variable. The results give clear hints regarding optimal fluid parameters of the analyzed process and deepen

  20. Multi-objective thermodynamic optimization of an irreversible regenerative Brayton cycle using evolutionary algorithm and decision making

    Directory of Open Access Journals (Sweden)

    Rajesh Kumar

    2016-06-01

    Full Text Available Brayton heat engine model is developed in MATLAB simulink environment and thermodynamic optimization based on finite time thermodynamic analysis along with multiple criteria is implemented. The proposed work investigates optimal values of various decision variables that simultaneously optimize power output, thermal efficiency and ecological function using evolutionary algorithm based on NSGA-II. Pareto optimal frontier between triple and dual objectives is obtained and best optimal value is selected using Fuzzy, TOPSIS, LINMAP and Shannon’s entropy decision making methods. Triple objective evolutionary approach applied to the proposed model gives power output, thermal efficiency, ecological function as (53.89 kW, 0.1611, −142 kW which are 29.78%, 25.86% and 21.13% lower in comparison with reversible system. Furthermore, the present study reflects the effect of various heat capacitance rates and component efficiencies on triple objectives in graphical custom. Finally, with the aim of error investigation, average and maximum errors of obtained results are computed.

  1. Organic Rankine-cycle power systems working fluids study. Topical report No. 1: Fluorinol 85

    Science.gov (United States)

    Jain, M. L.; Demirgian, J. C.; Cole, R. L.

    1986-09-01

    The thermal stability limits and degradation rates of Fluorinol 85 as a function of maximum cycle temperatures are determined. Following the design and construction of a dynamic test loop capable of simulating the thermodynamic conditions of possible prototypical organic Rankine-cycle (ORC) power systems, several test runs were completed. The Fluorinol 85 test loop was operated for about 3800 h at a temperature range of 525 to 600 F. Both liquid and noncondensable vapor (gas) samples were drawn periodically and analyzed using capillary column gas chromatography, gas chromatography/mass spectrometry and mass spectrometry. Results indicate that Fluorinol 85 would not decompose significantly over an extended period, up to a maximum cycle temperature of 550 F. However, 506-h data at 575 F show initiation of significant degradation. The 770-h data at 600 F, using a fresh charge of Fluorinol 85, indicate an annual degradation rate of more than 17.2%. The most significant degradation product observed is hydrofluoric acid, which could cause severe corrosion in an ORC system. Removal of the hydrofluoric acid and prevention of temperature extremes are necessary for an ORC system using Fluorinol 85 as a working fluid.

  2. Thermodynamic assessment of impact of inlet air cooling techniques on gas turbine and combined cycle performance

    International Nuclear Information System (INIS)

    Mohapatra, Alok Ku; Sanjay

    2014-01-01

    The article is focused on the comparison of impact of two different methods of inlet air cooling (vapor compression and vapor absorption cooling) integrated to a cooled gas turbine based combined cycle plant. Air-film cooling has been adopted as the cooling technique for gas turbine blades. A parametric study of the effect of compressor pressure ratio, compressor inlet temperature (T i , C ), turbine inlet temperature (T i , T ), ambient relative humidity and ambient temperature on performance parameters of plant has been carried out. Optimum T i , T corresponding to maximum plant efficiency of combined cycle increases by 100 °C due to the integration of inlet air cooling. It has been observed that vapor compression cooling improves the efficiency of gas turbine cycle by 4.88% and work output by 14.77%. In case of vapor absorption cooling an improvement of 17.2% in gas cycle work output and 9.47% in gas cycle efficiency has been observed. For combined cycle configuration, however, vapor compression cooling should be preferred over absorption cooling in terms of higher plant performance. The optimum value of compressor inlet temperature has been observed to be 20 °C for the chosen set of conditions for both the inlet air cooling schemes. - Highlights: • Inlet air cooling improves performance of cooled gas turbine based combined cycle. • Vapor compression inlet air cooling is superior to vapor absorption inlet cooling. • For every turbine inlet temperature, there exists an optimum pressure ratio. • The optimum compressor inlet temperature is found to be 293 K

  3. Improving geothermal power plants with a binary cycle

    Science.gov (United States)

    Tomarov, G. V.; Shipkov, A. A.; Sorokina, E. V.

    2015-12-01

    The recent development of binary geothermal technology is analyzed. General trends in the introduction of low-temperature geothermal sources are summarized. The use of single-phase low-temperature geothermal fluids in binary power plants proves possible and expedient. The benefits of power plants with a binary cycle in comparison with traditional systems are shown. The selection of the working fluid is considered, and the influence of the fluid's physicochemical properties on the design of the binary power plant is discussed. The design of binary power plants is based on the chemical composition and energy potential of the geothermal fluids and on the landscape and climatic conditions at the intended location. Experience in developing a prototype 2.5 MW Russian binary power unit at Pauzhetka geothermal power plant (Kamchatka) is outlined. Most binary systems are designed individually for a specific location. Means of improving the technology and equipment at binary geothermal power plants are identified. One option is the development of modular systems based on several binary systems that employ the heat from the working fluid at different temperatures.

  4. Thermodynamic Simulation on the Performance of Twin Screw Expander Applied in Geothermal Power Generation

    Directory of Open Access Journals (Sweden)

    Yuanqu Qi

    2016-08-01

    Full Text Available A three-dimensional (3D geometry model of twin screw expander has been developed in this paper to measure and analyze geometric parameters such as groove volume, suction port area, and leakage area, which can be described as functions of rotation angle of male rotor. Taking the suction loss, leakage loss, and real gas effect into consideration, a thermodynamic model is developed using continuity and energy conservation equation. The developed model is verified by comparing predicted results of power output and internal efficiency with experimental data. Based on the model, the relationship between mass flow rate through inlet port and leakage path with rotation angle of male rotor as well as effects of the inlet parameter and operating parameter on the performance of the expander are analyzed.

  5. Experimental and thermodynamic analysis of a bottoming Organic Rankine Cycle (ORC) of gasoline engine using swash-plate expander

    International Nuclear Information System (INIS)

    Galindo, J.; Ruiz, S.; Dolz, V.; Royo-Pascual, L.; Haller, R.; Nicolas, B.; Glavatskaya, Y.

    2015-01-01

    Highlights: • An experimental analysis of an ORC is presented and applied to a gasoline engine. • 28 Steady-state operating points have been tested to evaluate expander performance. • Optimum points have been used to analyze power balances and cycle efficiencies. - Abstract: This paper deals with the experimental testing of an Organic Rankine Cycle (ORC) integrate in a 2 liter turbocharged gasoline engine using ethanol as working fluid. The main components of the cycle are a boiler, a condenser, a pump and a swash-plate expander. Five engine operating points have been tested, they correspond to a nominal heat input into the boiler of 5, 12, 20, 25 and 30 kW. With the available bill of material based on prototypes, power balances and cycles efficiencies were estimated, obtaining a maximum improvement in the ICE mechanical power and an expander shaft power of 3.7% and 1.83 kW respectively. A total of 28 steady-state operating points were measured to evaluate performance of the swash-plate expander prototype. Operating parameters of the expander, such as expander speed and expansion ratio, were shifted. The objective of the tests is to master the system and understand physical parameters influence. The importance of each parameter was analyzed by fixing all the parameters, changing each time one specific value. In these sensitivity studies, maximum ideal and real Rankine efficiency value of 19% and 6% were obtained respectively

  6. Investigations on the application of zeotropic fluid mixtures in the organic rankine cycle for the geothermal power generation; Untersuchung zum Einsatz von zeotropen Fluidgemischen im Organic Rankine Cycle fuer die geothermische Stromerzeugung

    Energy Technology Data Exchange (ETDEWEB)

    Heberle, Florian

    2013-04-01

    The organic rankine cycle is a thermodynamic cycle process which uses an organic fluid working fluid instead of water in comparison to the commercial rankine process. The organic rankine cycle facilitates sufficiently high pressures at moderate temperatures. The organic rankine cycle significantly expands the technically possible and economically feasible ranges of application of such heat and power processes. The geothermal power is a very attractive field of application. Thermal water with a temperature of nearly 100 Celsius can be used for the power generation by means of the organic rankine cycle. Especially zeotropic mixtures are interesting as a working fluid. This is due to a non-isothermal phase change to a temperature glide which adapts very well to the temperature progress of the heat source. The author of the book under consideration reports on the application of different mixtures in the organic rankine cycle. The evaluation is based on a thermodynamic analysis and considers also toxicological, ecologic, technical as well as economic aspects.

  7. Coherence-limited solar power conversion: the fundamental thermodynamic bounds and the consequences for solar rectennas

    Science.gov (United States)

    Mashaal, Heylal; Gordon, Jeffrey M.

    2014-10-01

    Solar rectifying antennas constitute a distinct solar power conversion paradigm where sunlight's spatial coherence is a basic constraining factor. In this presentation, we derive the fundamental thermodynamic limit for coherence-limited blackbody (principally solar) power conversion. Our results represent a natural extension of the eponymous Landsberg limit, originally derived for converters that are not constrained by the radiation's coherence, and are irradiated at maximum concentration (i.e., with a view factor of unity to the solar disk). We proceed by first expanding Landsberg's results to arbitrary solar view factor (i.e., arbitrary concentration and/or angular confinement), and then demonstrate how the results are modified when the converter can only process coherent radiation. The results are independent of the specific power conversion mechanism, and hence are valid for diffraction-limited as well as quantum converters (and not just classical heat engines or in the geometric optics regime). The derived upper bounds bode favorably for the potential of rectifying antennas as potentially high-efficiency solar converters.

  8. Thermodynamic analysis of an integrated gasification solid oxide fuel cell plant combined with an organic Rankine cycle

    DEFF Research Database (Denmark)

    Pierobon, Leonardo; Rokni, Masoud; Larsen, Ulrik

    2013-01-01

    into a fixed bed gasification plant to produce syngas which fuels the combined solid oxide fuel cells e organic Rankine cycle system to produce electricity. More than a hundred fluids are considered as possible alternative for the organic cycle using non-ideal equations of state (or state-of-the-art equations......A 100 kWe hybrid plant consisting of gasification system, solid oxide fuel cells and organic Rankine cycle is presented. The nominal power is selected based on cultivation area requirement. For the considered output a land of around 0.5 km2 needs to be utilized. Woodchips are introduced...... achieved by simple and double stage organic Rankine cycle plants and around the same efficiency of a combined gasification, solid oxide fuel cells and micro gas turbine plant. © 2013 Elsevier Ltd. All rights reserved....

  9. Life cycle cost analysis of wind power considering stochastic uncertainties

    International Nuclear Information System (INIS)

    Li, Chiao-Ting; Peng, Huei; Sun, Jing

    2014-01-01

    This paper presents a long-term cost analysis of wind power and compares its competitiveness to non-renewable generating technologies. The analysis considers several important attributes related to wind intermittency that are sometimes ignored in traditional generation planning or LCOE (levelized cost of energy) studies, including the need for more nameplate capacity due to intermittency, hourly fluctuations in wind outputs and cost for reserves. The competitiveness of wind power is assessed by evaluating four scenarios: 1) adding natural gas generating capacity to the power grid; 2) adding coal generating capacity to the power grid; 3) adding wind capacity to the power grid; and, 4) adding wind capacity and energy storage to the power grid where an energy storage device is used to cover wind intermittency. A case study in the state of Michigan is presented to demonstrate the use of the proposed methodology, in which a time horizon from 2010 to 2040 is considered. The results show that wind energy will still be more expensive than natural gas power plants in the next three decades, but will be cheaper than coal capacities if wind intermittency is mitigated. Furthermore, if the costs of carbon emissions and environmental externalities are considered, wind generation will be a competitive option for grid capacity expansion. - Highlights: • The competitiveness of wind power is analyzed via life cycle cost analysis. • Wind intermittency and reserve costs are explicitly considered in the analysis. • Results show that wind is still more expensive than natural gas power plants. • Wind can be cheaper than coal capacities if wind intermittency is mitigated. • Wind will be competitive if costs of carbon emissions are considered

  10. Model Predictive Control of Integrated Gasification Combined Cycle Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    B. Wayne Bequette; Priyadarshi Mahapatra

    2010-08-31

    The primary project objectives were to understand how the process design of an integrated gasification combined cycle (IGCC) power plant affects the dynamic operability and controllability of the process. Steady-state and dynamic simulation models were developed to predict the process behavior during typical transients that occur in plant operation. Advanced control strategies were developed to improve the ability of the process to follow changes in the power load demand, and to improve performance during transitions between power levels. Another objective of the proposed work was to educate graduate and undergraduate students in the application of process systems and control to coal technology. Educational materials were developed for use in engineering courses to further broaden this exposure to many students. ASPENTECH software was used to perform steady-state and dynamic simulations of an IGCC power plant. Linear systems analysis techniques were used to assess the steady-state and dynamic operability of the power plant under various plant operating conditions. Model predictive control (MPC) strategies were developed to improve the dynamic operation of the power plants. MATLAB and SIMULINK software were used for systems analysis and control system design, and the SIMULINK functionality in ASPEN DYNAMICS was used to test the control strategies on the simulated process. Project funds were used to support a Ph.D. student to receive education and training in coal technology and the application of modeling and simulation techniques.

  11. Solar power satellite life-cycle energy recovery consideration

    Science.gov (United States)

    Weingartner, S.; Blumenberg, J.

    The construction, in-orbit installation and maintenance of a solar power satellite (SPS) will demand large amounts of energy. As a minimum requirement for an energy effective power satellite it is asked that this amount of energy be recovered. The energy effectiveness in this sense resulting in a positive net energy balance is a prerequisite for cost-effective power satellite. This paper concentrates on life-cycle energy recovery instead on monetary aspects. The trade-offs between various power generation systems (different types of solar cells, solar dynamic), various construction and installation strategies (using terrestrial or extra-terrestrial resources) and the expected/required lifetime of the SPS are reviewed. The presented work is based on a 2-year study performed at the Technical University of Munich. The study showed that the main energy which is needed to make a solar power satellite a reality is required for the production of the solar power components (up to 65%), especially for the solar cell production. Whereas transport into orbit accounts in the order of 20% and the receiving station on earth (rectenna) requires about 15% of the total energy investment. The energetic amortization time, i.e. the time the SPS has to be operational to give back the amount of energy which was needed for its production installation and operation, is about two years.

  12. Solar power satellite—Life-cycle energy recovery considerations

    Science.gov (United States)

    Weingartner, S.; Blumenberg, J.

    1995-05-01

    The construction, in-orbit installation and maintenance of a solar power satellite (SPS) will demand large amounts of energy. As a minimum requirement for an energy effective power satellite it is asked that this amount of energy be recovered. The energy effectiveness in this sense resulting in a positive net energy balance is a prerequisite for a cost-effective power satellite. This paper concentrates on life-cycle energy recovery instead of monetary aspects. The trade-offs between various power generation systems (different types of solar cells, solar dynamic), various construction and installation strategies (using terrestrial or extra-terrestrial resources) and the expected/required lifetime of the SPS are reviewed. The presented work is based on a 2-year study performed at the Technical University of Munich. The study showed that the main energy which is needed to make a solar power satellite a reality is required for the production of the solar power plant components (up to 65%), especially for the solar cell production. Whereas transport into orbit accounts in the order of 20% and the receiving station on Earth (rectenna) requires in the order of 15% of the total energy investment. The energetic amortization time, i.e. the time the SPS has to be operational to give back the amount of energy which was needed for its production, installation and operation, is in the order of two years.

  13. Modelling and exergoeconomic-environmental analysis of combined cycle power generation system using flameless burner for steam generation

    International Nuclear Information System (INIS)

    Hosseini, Seyed Ehsan; Barzegaravval, Hasan; Ganjehkaviri, Abdolsaeid; Wahid, Mazlan Abdul; Mohd Jaafar, M.N.

    2017-01-01

    Highlights: • Using flameless burner as a supplementary firing system after gas turbine is modeled. • Thermodynamic, economic and environmental analyses of this model are performed. • Efficiency of the plant increases about 6% and CO_2 emission decreases up to 5.63% in this design. • Available exergy for work production in both gas cycle and steam cycle increases in this model. - Abstract: To have an optimum condition for the performance of a combined cycle power generation, using supplementary firing system after gas turbine was investigated by various researchers. Since the temperature of turbine exhaust is higher than auto-ignition temperature of the fuel in optimum condition, using flameless burner is modelled in this paper. Flameless burner is installed between gas turbine cycle and Rankine cycle of a combined cycle power plant which one end is connected to the outlet of gas turbine (as primary combustion oxidizer) and the other end opened to the heat recovery steam generator. Then, the exergoeconomic-environmental analysis of the proposed model is evaluated. Results demonstrate that efficiency of the combined cycle power plant increases about 6% and CO_2 emission reduces up to 5.63% in this proposed model. It is found that the variation in the cost is less than 1% due to the fact that a cost constraint is implemented to be equal or lower than the design point cost. Moreover, exergy of flow gases increases in all points except in heat recovery steam generator. Hence, available exergy for work production in both gas cycle and steam cycle will increase in new model.

  14. Refuse Derived Fuel (RDF) production and gasification in a pilot plant integrated with an Otto cycle ICE through Aspen plus™ modelling: Thermodynamic and economic viability.

    Science.gov (United States)

    Násner, Albany Milena Lozano; Lora, Electo Eduardo Silva; Palacio, José Carlos Escobar; Rocha, Mateus Henrique; Restrepo, Julian Camilo; Venturini, Osvaldo José; Ratner, Albert

    2017-11-01

    This work deals with the development of a Refuse Derived Fuel (RDF) gasification pilot plant using air as a gasification agent. A downdraft fixed bed reactor is integrated with an Otto cycle Internal Combustion Engine (ICE). Modelling was carried out using the Aspen Plus™ software to predict the ideal operational conditions for maximum efficiency. Thermodynamics package used in the simulation comprised the Non-Random Two-Liquid (NRTL) model and the Hayden-O'Connell (HOC) equation of state. As expected, the results indicated that the Equivalence Ratio (ER) has a direct influence over the gasification temperature and the composition of the Raw Produced Gas (RPG), and effects of ER over the Lower Heating Value (LHV) and Cold Gasification Efficiency (CGE) of the RPG are also discussed. A maximum CGE efficiency of 57-60% was reached for ER values between 0.25 and 0.3, also an average reactor temperature values in the range of 680-700°C, with a peak LHV of 5.8MJ/Nm 3 . RPG was burned in an ICE, reaching an electrical power of 50kW el . The economic assessment of the pilot plant implementation was also performed, showing the project is feasible, with power above 120kW el with an initial investment of approximately US$ 300,000. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Exergetic and economic evaluation of the effect of HRSG configurations on the performance of combined cycle power plants

    International Nuclear Information System (INIS)

    Tajik Mansouri, Mohammad; Ahmadi, Pouria; Ganjeh Kaviri, Abdolsaeid; Jaafar, Mohammad Nazri Mohd

    2012-01-01

    Highlights: ►To conduct the comprehensive exergy and economic analysis for advanced combined cycle power plant. ►To study three different HRSG configurations, dual and triple pressure HRSG, based on thermodynamic relations. ►To have a better performance assessment of the system studied using exergy and economic criteria. - Abstract: In the present research study, the effect of HRSG pressure levels on exergy efficiency of combined cycle power plants is investigated. Hence, three types of gas turbine combined cycles, with the same gas turbine as a topping cycle are evaluated. A double pressure, and two triple pressure HRSGs (with and without reheat) are modeled. The results show how an increase in the number of pressure levels of the HRSG affect the exergy losses due to heat transfer in the HRSG and the exhaust of flue gas to the stack. Moreover, the results show that an increase in the number of pressure levels affects the exergy destruction rate in HRSG, and as a result, it causes a tangible increase in exergy efficiency of the whole cycle. The results from thermodynamic analysis show that the losses due to heat transfer in the HRSG and the exhaust of flue gas to the stack in a triple pressure reheat combined cycle are less than the other cases. From the economic analysis, it is found that increasing the number of pressure levels of steam generation leads to an increase for the total and specific investment cost of the plant for about 6% and 4% respectively. The net present value (NPV) of the plant increases for about 7% for triple pressure reheat compared to with the double pressure CCPP. Therefore, the results of economic analysis show that it is economically justifiable to increase the number of pressure levels of steam generation in HRSG.

  16. Life-cycle air emissions from PV power systems

    International Nuclear Information System (INIS)

    Watt, M.E.; Johnson, A.J.; Outhred, H.R.; Ellis, M.

    1998-01-01

    This paper addresses the air emission of grid supply versus grid-connected and off-grid photovoltaic power generation, using the framework of life-cycle assessment, in the contents of rural household energy supply in Australia. Emissions of carbon dioxide, sulphur dioxde and nitrous oxides are calculated for the three life-cycle stages of manufacture, use and disposal. Sensitivities to materials and data inputs, as well as to component efficiencies, lifetimes and sizing are discussed. For each supply option, demand management options, including insulation and appliance choice, and the substitution of solar heating or bottled gas for electricity are considered. The best option in all cases, in terms of life-cycle air emissions, is a grid-connected photovoltaic system used to supply an energy-efficient household with a mix of solar, gas and electric appliances. However, in financial terms, with current Australian energy prices, this option represents a high capital and life-cycle costs. Additionally, for the grid options, electricity costs do not significantly disadvantage the high demand scenarios. Both results provide a clear illustration of current Australian energy-pricing policies being in conflict with long-term environmental sustainability. (Author)

  17. Power ramping/cycling experience and operational recommendations in KWU power plants

    International Nuclear Information System (INIS)

    Jan, R. von; Wunderlich, F.; Holzer, R.

    1980-01-01

    The power cycling and ramping experience of KWU is based on experiments in test and commercial reactors, and on evaluation of plant operation (PHWR, PWR and BWR). Power cycling of fuel rods have never lead to PCI failures. In ramping experiments, for fast ramps PCI failure thresholds of 480/420 W/cm are obtained at 12/23 GWd/t(U) burn-up for pressurized PWR fuel. No failures occurred during limited exceedance of the threshold with reduced ramp rate. Operational recommendations used by KWU are derived from experiments and plant experience. The effects of ramping considerations on plant operation is discussed. No rate restrictions are required for start-ups during an operating cycle or load follow operation within set limits for the distortion of the local power distribution. In a few situations, e.g. start-up after refueling, ramp rates of 1 to 5 %/h are recommended depending on plant and fuel design

  18. Utilisation de mélanges non-azéotropiques dans les cycles thermodynamiques à compression Use of Non-Azeotropic Mixtures in Thermodynamic Compression Cycles

    Directory of Open Access Journals (Sweden)

    Ambrosino J. L.

    2006-11-01

    Full Text Available L'utilisation de mélanges non-azéotropiques comme fluides frigorigènes présente différents avantages en ce qui concerne le fonctionnement des installations de réfrigération / conditionnement / chauffage mettant en oeuvre des cycles thermodynamiques à compression avec changement de phase. En outre, de tels mélanges représentent une alternative intéressante aux corps purs actuellement recherchés pour résoudre les problèmes d'environnement liés à la destruction de la couche d'ozone. Cet article analyse les connaissances acquises concernant la mise en oeuvre d'une telle solution. The use of non-azeotropic mixtures as refrigerants has various advantages concerning the operating of refrigeration / air-conditioning / heating installations implementing thermodynamic compression cycles with a phase change. Likewise, such mixtures represent an interesting alternative to pure components which are now being looked to as a solution to environmental problems linked to the destruction of the ozone layer. This article analyzes what is known about the implementation of such a solution.

  19. Technical comparison between Integrated Gasification Combined Cycle (IGCC) and Natural Gas Combined Cycle (NGCC) power plants

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, Pablo Andres Silva; Venturini, Osvaldo Jose; Lora, Electo Eduardo Silva [Federal University of Itajuba - UNIFEI, MG (Brazil). Excellence Group in Thermal Power and Distributed Generation - NEST], e-mails: osvaldo@unifei.edu.br, electo@unifei.edu.br

    2010-07-01

    Among the emerging clean coal technologies for power generation, Integrated Gasification Combined Cycle (IGCC) and Natural Gas Combined Cycle (NGCC) systems are receiving considerable attention as a potentially attractive option to reduce the emissions of greenhouse gases (GHG). The main reason is because these systems has high efficiency and low emissions in comparison with traditional power generation plants. Currently in IGCC and NGCC systems at demonstration stage is been considered to implement CCS technology. CO{sub 2} emissions can be avoided in a gasification-based power plant because by transferring almost all carbon compounds to CO{sub 2} through the water gas shift (WGS) reaction, then removing the CO{sub 2} before it is diluted in the combustion stage. The aim of this study is to compare the technical performance of an IGCC system that uses Brazilian coal and petroleum coke as fuel with a NGCC system, with the same fixed output power of 450 MW. The first section of this paper presents the plant configurations of IGCC systems. The following section presents an analysis of NGCC technology. (author)

  20. Electricity, nuclear power and fuel cycle in OECD countries

    International Nuclear Information System (INIS)

    1988-01-01

    A questionnaire on Electricity Generation, Nuclear Power and Fuel Cycle Data is distributed annually to OECD Member Countries. In the questionnaire of January 1988, countries were asked to provide data for 1986 and 1987 and most likely projections up to the year 2005. The replies to the questionnaire (or estimates for unavailable data) are presented in this Booklet. Data for 1987 are provisional for several countries. The data on electricity generation and electric capacity are presented to the year 2005, and the data on fuel cycle services to the year 2000. The Addendum contains an analysis of the present and past projections for installed nuclear capacity to 2000. It shows the total capacity of those plants connected to the grid, under construction and firmly planned to be in operation in 2000 as 282 GWe. The new projection of 300 GWe is above this estimate, indicating that some countries are considering further expansion of their nuclear capacities within this time-frame [fr

  1. Analysis of oxygen-enhanced combustion of gas power cycle

    Energy Technology Data Exchange (ETDEWEB)

    Maidana, Cristiano Frandalozo; Carotenuto, Adriano; Schneider, Paulo Smith [Universidade Federal do Rio Grande do Sul (GESTE/UFRGS), Porto Alegre, RS (Brazil). Grupo de Estudos Termicos e Energeticos], E-mails: cristiano.maidana@ufrgs.br, pss@mecanica.ufrgs.br

    2010-07-01

    The majority of combustion processes use air as oxidant, roughly taken as 21% O{sub 2} and 79% N{sub 2}, by volume. In many cases, these processes can be enhanced by using an oxidant that contains higher proportion of O{sub 2} than in air. This is known as oxygen-enhanced combustion or OEC, and can bring important benefits like higher thermal efficiencies, lower exhaust gas volumes, higher heat transfer efficiency, reduction fuel consumption, reduced equipment costs and substantially pollutant emissions reduction. Within this scenario, this paper aims to investigate the influence of 21-30% oxygen concentration on the performance of a air-fired natural gas fueled power plant. This power plant operates under a Brayton cycle with models with the help of an air flow splitter after the compressor output in order to dose the oxygen rate of combustion and to keep the flue gas intake of the turbine at a prescribed temperature. Simulations shows that the enhancing of the oxidant stream reduced fuel consumption of about 10%, driven by higher adiabatic flame temperatures, which improves thermal and heat transfer efficiencies. A conclusion obtained is that the use of oxygen in higher proportions can be a challenge to retrofit existing air-fired natural gas power turbine cycles, because of the technological limitation of its materials with higher flame temperatures. (author)

  2. Fuel cycle comparison of distributed power generation technologies

    International Nuclear Information System (INIS)

    Elgowainy, A.; Wang, M.Q.

    2008-01-01

    The fuel-cycle energy use and greenhouse gas (GHG) emissions associated with the application of fuel cells to distributed power generation were evaluated and compared with the combustion technologies of microturbines and internal combustion engines, as well as the various technologies associated with grid-electricity generation in the United States and California. The results were primarily impacted by the net electrical efficiency of the power generation technologies and the type of employed fuels. The energy use and GHG emissions associated with the electric power generation represented the majority of the total energy use of the fuel cycle and emissions for all generation pathways. Fuel cell technologies exhibited lower GHG emissions than those associated with the U.S. grid electricity and other combustion technologies. The higher-efficiency fuel cells, such as the solid oxide fuel cell (SOFC) and molten carbonate fuel cell (MCFC), exhibited lower energy requirements than those for combustion generators. The dependence of all natural-gas-based technologies on petroleum oil was lower than that of internal combustion engines using petroleum fuels. Most fuel cell technologies approaching or exceeding the DOE target efficiency of 40% offered significant reduction in energy use and GHG emissions

  3. Total life cycle cost model for electric power stations

    International Nuclear Information System (INIS)

    Cardullo, M.W.

    1995-01-01

    The Total Life Cycle Cost (TLCC) model for electric power stations was developed to provide a technology screening model. The TLCC analysis involves normalizing cost estimates with respect to performance standards and financial assumptions and preparing a profile of all costs over the service life of the power station. These costs when levelized present a value in terms of a utility electricity rate. Comparison of cost and the pricing of the electricity for a utility shows if a valid project exists. Cost components include both internal and external costs. Internal costs are direct costs associated with the purchase, and operation of the power station and include initial capital costs, operating and maintenance costs. External costs result from societal and/or environmental impacts that are external to the marketplace and can include air quality impacts due to emissions, infrastructure costs, and other impacts. The cost stream is summed (current dollars) or discounted (constant dollars) to some base year to yield a overall TLCC of each power station technology on a common basis. While minimizing life cycle cost is an important consideration, it may not always be a preferred method for some utilities who may prefer minimizing capital costs. Such consideration does not always result in technology penetration in a marketplace such as the utility sector. Under various regulatory climates, the utility is likely to heavily weigh initial capital costs while giving limited consideration to other costs such as societal costs. Policy makers considering external costs, such as those resulting from environmental impacts, may reach significantly different conclusions about which technologies are most advantageous to society. The TLCC analysis model for power stations was developed to facilitate consideration of all perspectives

  4. Extended Pulse-Powered Humidity-Freeze Cycling for Testing Module-Level Power Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Hacke, Peter L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rodriguez, Miguel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kempe, Michael D [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Repins, Ingrid L [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-11-28

    An EMI suppression capacitor (polypropylene film type) failed by 'popcorning' due to vapor outgassing in pulse powered humidity-freeze cycles. No shorts or shunts could be detected despite mildly corroded metallization visible in the failed capacitor. Humidity-freeze cycling is optimized to break into moisture barriers. However, further studies will be required on additional module level power electronic (MLPE) devices to optimize the stress testing for condensation to precipitate any weakness to short circuiting and other humidity/bias failure modes.

  5. Potassium Rankine cycle power conversion systems for lunar-Mars surface power

    International Nuclear Information System (INIS)

    Holcomb, R.S.

    1992-01-01

    The potassium Rankine cycle has good potential for application to nuclear power systems for surface power on the moon and Mars. A substantial effort on the development of the power conversion system was carried out in the 1960's which demonstrated successful operation of components made of stainless steel at moderate temperatures. This technology could be applied in the near term to produce a 360 kW(e) power system by coupling a stainless steel power conversion system to the SP-100 reactor. Improved performance could be realized in later systems by utilizing niobium or tantalum refractory metal alloys in the reactor and power conversion system. The design characteristics and estimated mass of power systems for each of three technology levels are presented in the paper

  6. ALKASYS, Rankine-Cycle Space Nuclear Power System

    International Nuclear Information System (INIS)

    2001-01-01

    1 - Description of program or function: The program ALKASYS is used for the creation of design concepts of multimegawatt space power systems that employ potassium Rankine power conversion cycles. 2 - Method of solution: ALKASYS calculates performance and design characteristics and mass estimates for the major subsystems composing the total power system. Design and engineering performance characteristics are determined by detailed engineering procedures rather than by empirical algorithms. Mass estimates are developed using basic design principles augmented in some cases by empirical coefficients determined from the literature. The reactor design is based on a fast spectrum, metallic-clad rod fuel element containing UN pellets. 3 - Restrictions on the complexity of the problem: ALKASYS was developed primarily for the analysis of systems with electric power in the range from 1,000 to 25,000 kW(e) and full-power life from 1 to 10 years. The program should be used with caution in systems that are limited by heat flux (which might indicate need for extended surfaces on fuel elements) or criticality (which might indicate the need for other geometries or moderators)

  7. Response of the dynamic and thermodynamic structure of the stratosphere to the solar cycle in the boreal winter

    Science.gov (United States)

    Shi, Chunhua; Gao, Yannan; Cai, Juan; Guo, Dong; Lu, Yan

    2018-04-01

    The response of the dynamic and thermodynamic structure of the stratosphere to the solar cycle in the boreal winter is investigated based on measurements of the solar cycle by the Spectral Irradiance Monitor onboard the SORCE satellite, monthly ERA-Interim Reanalysis data from the European Center for Medium-Range Weather Forecasts, the radiative transfer scheme of the Beijing Climate Center (BCC-RAD) and a multiple linear regression model. The results show that during periods of strong solar activity, the solar shortwave heating anomaly from the climatology in the tropical upper stratosphere triggers a local warm anomaly and strong westerly winds in mid-latitudes, which strengthens the upward propagation of planetary wave 1 but prevents that of wave 2. The enhanced westerly jet makes a slight adjustment to the propagation path of wave 1, but prevents wave 2 from propagating upward, decreases the dissipation of wave 2 in the extratropical upper stratosphere and hence weakens the Brewer-Dobson circulation. The adiabatic heating term in relation to the Brewer-Dobson circulation shows anomalous warming in the tropical lower stratosphere and anomalous cooling in the mid-latitude upper stratosphere.

  8. Thermodynamic and heat transfer analysis of LNG energy recovery for power production

    International Nuclear Information System (INIS)

    Franco, A; Casarosa, C

    2014-01-01

    An important option to transport the gas is to convert it into liquid natural gas (LNG) and convey it using insulated LNG tankers. At receiving terminals, the LNG is offloaded into storage tanks and then pumped at the required pressure and vaporized for final transmission to the pipeline. The LNG production process consumes a considerable amount of energy, while the cold availability, as also known as cold energy, has been stored in LNG. At a receiving terminal, LNG needs to be evaporated into gas at environmental temperature before fed into the gas distribution system. Seawater is commonly used for the regasification process of the LNG. In the present paper, after a general analysis of the perspectives of the various thermodynamic schemes proposed for power production from the regasification, a detailed analysis of enhanced direct expansion system is carried out in order to identify the upper level of the energy that can be recovered. The analysis outlines that power production typical of optimized ORC plant configurations (120 kJ/kg) can be obtained with direct expansion solutions

  9. Thermodynamic and heat transfer analysis of LNG energy recovery for power production

    Science.gov (United States)

    Franco, A.; Casarosa, C.

    2014-11-01

    An important option to transport the gas is to convert it into liquid natural gas (LNG) and convey it using insulated LNG tankers. At receiving terminals, the LNG is offloaded into storage tanks and then pumped at the required pressure and vaporized for final transmission to the pipeline. The LNG production process consumes a considerable amount of energy, while the cold availability, as also known as cold energy, has been stored in LNG. At a receiving terminal, LNG needs to be evaporated into gas at environmental temperature before fed into the gas distribution system. Seawater is commonly used for the regasification process of the LNG. In the present paper, after a general analysis of the perspectives of the various thermodynamic schemes proposed for power production from the regasification, a detailed analysis of enhanced direct expansion system is carried out in order to identify the upper level of the energy that can be recovered. The analysis outlines that power production typical of optimized ORC plant configurations (120 kJ/kg) can be obtained with direct expansion solutions.

  10. Energy analysis of nuclear power plants and their fuel cycle

    International Nuclear Information System (INIS)

    Held, C.; Moraw, G.; Schneeberger, M.; Szeless, A.

    1977-01-01

    Energy analysis has become an increasingly feasible and practical additional method for evaluating the engineering, economic and environmental aspects of power producing systems. Energy analysis compares total direct and indirect energy investment into construction and operation of power plants with their lifetime energy output. Statically we have applied this method to nuclear power producing sytems and their fuel cycles. Results were adapted to countries with various levels of industrialization and resources. With dynamic energy analysis different scenarios have been investigated. For comparison purposes fossil fueled and solar power plants have also been analyzed. By static evaluation it has been shown that for all types of power plants the energy investment for construction is shortly after plant startup being repaid by energy output. Static analyses of nuclear and fossil fuels have indicated values of fuel concentrations below which more energy is required for their utilization than can be obtained from the plants they fuel. In a further step these global results were specifically modified to the economic situations of countries with various levels of industrialization. Also the influence of energy imports upon energy analysis has been discussed. By dynamic energy analyses the cumulative energy requirements for specific power plant construction programs have been compared with their total energy output. Investigations of this sort are extremely valuable not only for economic reasons but especially for their usefulness in showing the advantages and disadvantages of a specific power program with respect to its alternatives. Naturally the impact of these investigations on the fuel requirements is of importance especially because of the today so often cited ''valuable cumulated fossil fuel savings''

  11. Closed Brayton cycle power conversion systems for nuclear reactors :

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Steven A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lipinski, Ronald J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vernon, Milton E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sanchez, Travis [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2006-04-01

    This report describes the results of a Sandia National Laboratories internally funded research program to study the coupling of nuclear reactors to gas dynamic Brayton power conversion systems. The research focused on developing integrated dynamic system models, fabricating a 10-30 kWe closed loop Brayton cycle, and validating these models by operating the Brayton test-loop. The work tasks were performed in three major areas. First, the system equations and dynamic models for reactors and Closed Brayton Cycle (CBC) systems were developed and implemented in SIMULINKTM. Within this effort, both steady state and dynamic system models for all the components (turbines, compressors, reactors, ducting, alternators, heat exchangers, and space based radiators) were developed and assembled into complete systems for gas cooled reactors, liquid metal reactors, and electrically heated simulators. Various control modules that use proportional-integral-differential (PID) feedback loops for the reactor and the power-conversion shaft speed were also developed and implemented. The simulation code is called RPCSIM (Reactor Power and Control Simulator). In the second task an open cycle commercially available Capstone C30 micro-turbine power generator was modified to provide a small inexpensive closed Brayton cycle test loop called the Sandia Brayton test-Loop (SBL-30). The Capstone gas-turbine unit housing was modified to permit the attachment of an electrical heater and a water cooled chiller to form a closed loop. The Capstone turbine, compressor, and alternator were used without modification. The Capstone systems nominal operating point is 1150 K turbine inlet temperature at 96,000 rpm. The annular recuperator and portions of the Capstone control system (inverter) and starter system also were reused. The rotational speed of the turbo-machinery is controlled by adjusting the alternator load by using the electrical grid as the load bank. The SBL-30 test loop was operated at

  12. Combined Cycle Power Generation Employing Pressure Gain Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Holley, Adam [United Technologies Corporation, East Hartford, CT (United States). Research Center

    2017-05-15

    The Phase I program assessed the potential benefit of applying pressure gain combustion (PGC) technology to a natural gas combined cycle power plant. A conceptual design of the PGC integrated gas turbine was generated which was simulated in a detailed system modeling tool. The PGC integrated system was 1.93% more efficient, produced 3.09% more power, and reduced COE by 0.58%. Since the PGC system used had the same fuel flow rate as the baseline system, it also reduced CO2 emissions by 3.09%. The PGC system did produce more NOx than standard systems, but even with the performanceand cost penalties associated with the cleanup system it is better in every measure. This technology benefits all of DOE’s stated program goals to improve plant efficiency, reduce CO2 production, and reduce COE.

  13. Multi-approach evaluations of a cascade-Organic Rankine Cycle (C-ORC) system driven by diesel engine waste heat: Part A – Thermodynamic evaluations

    International Nuclear Information System (INIS)

    Shu, Gequn; Yu, Guopeng; Tian, Hua; Wei, Haiqiao; Liang, Xingyu; Huang, Zhiyong

    2016-01-01

    Highlights: • A novel C-ORC system was proposed for recovering waste heat from a diesel engine. • Thermodynamic evaluations were conducted to explore C-ORC’s practical benefits. • C-ORC has significant heat-recovery capacities and efficiency-promotion potential. • Up to 16.0% of engine efficiency can be improved combining with C-ORC. - Abstract: A novel transcritical cascade-Organic Rankine Cycle (C-ORC) system was proposed to recover multi-grade waste heat from a typical heavy-duty diesel engine. The C-ORC comprises of a high-temperature ORC loop (HT-Loop) and a low temperature ORC loop (LT-Loop) to recover waste heat from an engine’s exhaust gas (EG), exhaust gas recirculation (EGR), jacket water (JW) and charge air (CA) in a cascaded pattern. In order to reveal the full performance of the C-ORC system, with due consideration to diesel’s complex practical running conditions, multi-approach evaluations were conducted containing two parts: Part A – thermodynamic evaluations of the energy and exergy aspects and Part B – techno-economic evaluations on costs and benefits aspects. This paper shows the Part A – evaluations of the C-ORC, focusing on indexes including recovered waste heat, net power output, thermal efficiencies and exergy efficiencies. First of all, distributions of the engine’s multi-grade waste heat were studied to reveal the characteristics and utilization potential of waste energy. The comparison and screening of working fluids were carried out next to find the best fluids for the HT-Loop and LT-Loop respectively based on the rated engine condition. Toluene, decane, cyclohexane and D4 were four proper alternatives for the HT-Loop while R143a, R125, R218 and R41 were four proper alternatives for the LT-Loop. Comparisons indicated that toluene and R143a made the perfect match for the C-ORC with the highest net power output (33.9 kW), thermal efficiency (9.9%) and exergy efficiency (39.1%). The rankings of the two groups of

  14. Dry/Wet Cycling and the Thermodynamics and Kinetics of Prebiotic Polymer Synthesis

    Directory of Open Access Journals (Sweden)

    David S. Ross

    2016-07-01

    Full Text Available The endoergic nature of protein and nucleic acid assembly in aqueous media presents two questions that are fundamental to the understanding of life’s origins: (i how did the polymers arise in an aqueous prebiotic world; and (ii once formed in some manner, how were they sufficiently persistent to engage in further chemistry. We propose here a quantitative resolution of these issues that evolved from recent accounts in which RNA-like polymers were produced in evaporation/rehydration cycles. The equilibrium Nm + Nn ↔ Nm+n + H2O is endoergic by about 3.3 kcal/mol for polynucleotide formation, and the system thus lies far to the left in the starting solutions. Kinetic simulations of the evaporation showed that simple Le Châtelier’s principle shifts were insufficient, but the introduction of oligomer-stabilizing factors of 5–10 kcal/mol both moved the process to the right and respectively boosted and retarded the elongation and hydrolysis rates. Molecular crowding and excluded volume effects in present-day cells yield stabilizing factors of that order, and we argue here that the crowded conditions in the evaporites generate similar effects. Oligomer formation is thus energetically preferred in those settings, but the process is thwarted in each evaporation step as diffusion becomes rate limiting. Rehydration dissipates disordered oligomer clusters in the evaporites, however, and subsequent dry/wet cycling accordingly “ratchets up” the system to an ultimate population of kinetically trappedthermodynamically preferred biopolymers.

  15. Performance analysis of a Kalina cycle for a central receiver solar thermal power plant with direct steam generation

    International Nuclear Information System (INIS)

    Modi, Anish; Haglind, Fredrik

    2014-01-01

    Solar thermal power plants have attracted increasing interest in the past few years – with respect to both the design of the various plant components, and extending the operation hours by employing different types of storage systems. One approach to improve the overall plant efficiency is to use direct steam generation with water/steam as both the heat transfer fluid in the solar receivers and the cycle working fluid. This enables operating the plant with higher turbine inlet temperatures. Available literature suggests that it is feasible to use ammonia-water mixtures at high temperatures without corroding the equipment by using suitable additives with the mixture. The purpose of the study reported here was to investigate if there is any benefit of using a Kalina cycle for a direct steam generation, central receiver solar thermal power plant with high live steam temperature (450 °C) and pressure (over 100 bar). Thermodynamic performance of the Kalina cycle in terms of the plant exergy efficiency was evaluated and compared with a simple Rankine cycle. The rates of exergy destruction for the different components in the two cycles were also calculated and compared. The results suggest that the simple Rankine cycle exhibits better performance than the Kalina cycle when the heat input is only from the solar receiver. However, when using a two-tank molten-salt storage system as the primary source of heat input, the Kalina cycle showed an advantage over the simple Rankine cycle because of about 33 % reduction in the storage requirement. The solar receiver showed the highest rate of exergy destruction for both the cycles. The rates of exergy destruction in other components of the cycles were found to be highly dependent on the amount of recuperation, and the ammonia mass fraction and pressure at the turbine inlet. - Highlights: •Kalina cycle for a central receiver solar thermal power plant with direct steam generation. •Rankine cycle shows better plant exergy

  16. Energy Balance of Nuclear Power Generation. Life Cycle Analyses of Nuclear Power

    International Nuclear Information System (INIS)

    Wallner, A.; Wenisch, A.; Baumann, M.; Renner, S.

    2011-01-01

    The accident at the Japanese nuclear power plant Fukushima in March 2011 triggered a debate about phasing out nuclear energy and the safety of nuclear power plants. Several states are preparing to end nuclear power generation. At the same time the operational life time of many nuclear power plants is reaching its end. Governments and utilities now need to take a decision to replace old nuclear power plants or to use other energy sources. In particular the requirement of reducing greenhouse gas emissions (GHG) is used as an argument for a higher share of nuclear energy. To assess the contribution of nuclear power to climate protection, the complete life cycle needs to be taken into account. Some process steps are connected to high CO2 emissions due to the energy used. While the processes before and after conventional fossil-fuel power stations can contribute up to 25% of direct GHG emission, it is up to 90 % for nuclear power (Weisser 2007). This report aims to produce information about the energy balance of nuclear energy production during its life cycle. The following key issues were examined: How will the forecasted decreasing uranium ore grades influence energy intensity and greenhouse emissions and from which ore grade on will no energy be gained anymore? In which range can nuclear energy deliver excess energy and how high are greenhouse gas emissions? Which factors including ore grade have the strongest impact on excess energy? (author)

  17. Combined Turbine and Cycle Optimization for Organic Rankine Cycle Power Systems—Part A: Turbine Model

    Directory of Open Access Journals (Sweden)

    Andrea Meroni

    2016-04-01

    Full Text Available Axial-flow turbines represent a well-established technology for a wide variety of power generation systems. Compactness, flexibility, reliability and high efficiency have been key factors for the extensive use of axial turbines in conventional power plants and, in the last decades, in organic Rankine cycle power systems. In this two-part paper, an overall cycle model and a model of an axial turbine were combined in order to provide a comprehensive preliminary design of the organic Rankine cycle unit, taking into account both cycle and turbine optimal designs. Part A presents the preliminary turbine design model, the details of the validation and a sensitivity analysis on the main parameters, in order to minimize the number of decision variables in the subsequent turbine design optimization. Part B analyzes the application of the combined turbine and cycle designs on a selected case study, which was performed in order to show the advantages of the adopted methodology. Part A presents a one-dimensional turbine model and the results of the validation using two experimental test cases from literature. The first case is a subsonic turbine operated with air and investigated at the University of Hannover. The second case is a small, supersonic turbine operated with an organic fluid and investigated by Verneau. In the first case, the results of the turbine model are also compared to those obtained using computational fluid dynamics simulations. The results of the validation suggest that the model can predict values of efficiency within ± 1.3%-points, which is in agreement with the reliability of classic turbine loss models such as the Craig and Cox correlations used in the present study. Values similar to computational fluid dynamics simulations at the midspan were obtained in the first case of validation. Discrepancy below 12 % was obtained in the estimation of the flow velocities and turbine geometry. The values are considered to be within a

  18. Thermodynamics investigation of a solar power system integrated oil and molten salt as heat transfer fluids

    International Nuclear Information System (INIS)

    Liu, Qibin; Bai, Zhang; Sun, Jie; Yan, Yuejun; Gao, Zhichao; Jin, Hongguang

    2016-01-01

    Highlights: • A new concentrating solar power system with a dual-solar field is proposed. • The superheated steam with more than 773 K is produced. • The performances of the proposed system are demonstrated. • The economic feasibility of the proposed system is validated. - Abstract: In this paper, a new parabolic trough solar power system that incorporates a dual-solar field with oil and molten salt as heat transfer fluids (HTFs) is proposed to effectively utilize the solar energy. The oil is chosen as a HTF in the low temperature solar field to heat the feeding water, and the high temperature solar field uses molten salt to superheat the steam that the temperature is higher than 773 K. The produced superheated steam enters a steam turbine to generate power. Energy analysis and exergy analysis of the system are implemented to evaluate the feasibility of the proposed system. Under considerations of variations of solar irradiation, the on-design and off-design thermodynamic performances of the system and the characteristics are investigated. The annual average solar-to-electric efficiency and the nominal efficiency under the given condition for the proposed solar thermal power generation system reach to 15.86% and 22.80%, which are higher than the reference system with a single HTF. The exergy losses within the solar heat transfer process of the proposed system are reduced by 7.8% and 45.23% compared with the solar power thermal systems using oil and molten salt as HTFs, respectively. The integrated approach with oil and molten salt as HTFs can make full use of the different physical properties of the HTFs, and optimize the heat transfer process between the HTFs and the water/steam. The exergy loss in the water evaporation and superheated process are reduced, the system efficiency and the economic performance are improved. The research findings provide a new approach for the improvement of the performances of solar thermal power plants.

  19. Performance analysis of a bio-gasification based combined cycle power plant employing indirectly heated humid air turbine

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, S., E-mail: sankha.deepp@gmail.com; Mondal, P., E-mail: mondal.pradip87@gmail.com; Ghosh, S., E-mail: sudipghosh.becollege@gmail.com [Department of Mechanical Engineering, Indian Institute of Engineering Science and Technology, Shibpur, Howrah – 711103, West Bengal (India)

    2016-07-12

    Rapid depletion of fossil fuel has forced mankind to look into alternative fuel resources. In this context, biomass based power generation employing gas turbine appears to be a popular choice. Bio-gasification based combined cycle provides a feasible solution as far as grid-independent power generation is concerned for rural electrification projects. Indirectly heated gas turbine cycles are promising alternatives as they avoid downstream gas cleaning systems. Advanced thermodynamic cycles have become an interesting area of study to improve plant efficiency. Water injected system is one of the most attractive options in this field of applications. This paper presents a theoretical model of a biomass gasification based combined cycle that employs an indirectly heated humid air turbine (HAT) in the topping cycle. Maximum overall electrical efficiency is found to be around 41%. Gas turbine specific air consumption by mass is minimum when pressure ratio is 6. The study reveals that, incorporation of the humidification process helps to improve the overall performance of the plant.

  20. Membranes for H2 generation from nuclear powered thermochemical cycles

    International Nuclear Information System (INIS)

    Nenoff, Tina Maria; Ambrosini, Andrea; Garino, Terry J.; Gelbard, Fred; Leung, Kevin; Navrotsky, Alexandra; Iyer, Ratnasabapathy G.; Axness, Marlene

    2006-01-01

    In an effort to produce hydrogen without the unwanted greenhouse gas byproducts, high-temperature thermochemical cycles driven by heat from solar energy or next-generation nuclear power plants are being explored. The process being developed is the thermochemical production of Hydrogen. The Sulfur-Iodide (SI) cycle was deemed to be one of the most promising cycles to explore. The first step of the SI cycle involves the decomposition of H 2 SO 4 into O 2 , SO 2 , and H 2 O at temperatures around 850 C. In-situ removal of O 2 from this reaction pushes the equilibrium towards dissociation, thus increasing the overall efficiency of the decomposition reaction. A membrane is required for this oxygen separation step that is capable of withstanding the high temperatures and corrosive conditions inherent in this process. Mixed ionic-electronic perovskites and perovskite-related structures are potential materials for oxygen separation membranes owing to their robustness, ability to form dense ceramics, capacity to stabilize oxygen nonstoichiometry, and mixed ionic/electronic conductivity. Two oxide families with promising results were studied: the double-substituted perovskite A x Sr 1-x Co 1-y B y O 3-δ (A=La, Y; B=Cr-Ni), in particular the family La x Sr 1-x Co 1-y Mn y O 3-δ (LSCM), and doped La 2 Ni 1-x M x O 4 (M = Cu, Zn). Materials and membranes were synthesized by solid state methods and characterized by X-ray and neutron diffraction, SEM, thermal analyses, calorimetry and conductivity. Furthermore, we were able to leverage our program with a DOE/NE sponsored H 2 SO 4 decomposition reactor study (at Sandia), in which our membranes were tested in the actual H 2 SO 4 decomposition step

  1. Thermodynamic performance of an auto-cascade ejector refrigeration cycle with mixed refrigerant R32 + R236fa

    International Nuclear Information System (INIS)

    Tan, Yingying; Wang, Lin; Liang, Kunfeng

    2015-01-01

    In this paper, an auto-cascade ejector refrigeration cycle (ACERC) is proposed to obtain lower refrigeration temperature based on conventional ejector refrigeration and auto-cascade refrigeration principle. The thermodynamic performance of ACERC is investigated theoretically. The zeotropic refrigerant mixture R32 + R236fa is used as its working fluid. A parametric analysis is conducted to evaluate the effects of some thermodynamic parameters on the cycle performance. The study shows that refrigerant mixture composition, condenser outlet temperature and evaporation pressure have effects on performance of ACERC. The theoretical results also indicate that the ACERC can achieve the lowest refrigeration temperature at the temperature level of −30 °C. The application of zeotropic refrigerant mixture auto-cascade refrigeration in the ejector refrigeration cycle can provide a new way to obtain lower refrigeration temperature utilizing low-grade thermal energy. - Highlights: • An auto-cascade ejector refrigerator with R32 + R236fa mixed refrigerant is proposed. • The cycle can obtain a refrigeration temperature at −30 °C temperature range. • The effects of some thermodynamic parameters on the cycle performance are evaluated

  2. The nuclear power cycle; Le cycle de l'energie nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    Fifty years after the first nuclear reactor come on-line, nuclear power is fourth among the world's primary energy sources, after oil, coal and gas. In 2002, there were 441 reactors in operation worldwide. The United States led the world with 104 reactors and an installed capacity of 100,000 MWe, or more than one fourth of global capacity. Electricity from nuclear energy represents 78% of the production in France, 57% in Belgium, 46% in Sweden, 40% in Switzerland, 39% in South Korea, 34% in Japan, 30% in Germany, 30% in Finland, 26% in Spain, 22% in Great Britain, 20% in the United States and 16% in Russia. Worldwide, 32 reactors are under construction, including 21 in Asia. This information document presents the Areva activities in the nuclear power cycle: the nuclear fuel, the nuclear reactors, the spent fuel reprocessing and recycling and nuclear cleanup and dismantling. (A.L.B.)

  3. Modeling the nonequilibrium effects in a nonquasi-equilibrium thermodynamic cycle based on steepest entropy ascent and an isothermal-isobaric ensemble

    International Nuclear Information System (INIS)

    Li, Guanchen; Spakovsky, Michael R. von

    2016-01-01

    Conventional first principle approaches for studying nonequilibrium or far-from-equilibrium processes depend on the mechanics of individual particles or quantum states. They also require many details of the mechanical features of a system to arrive at a macroscopic property. In contrast, thermodynamics provides an approach for determining macroscopic property values without going into these details, because the overall effect of particle dynamics results, for example, at stable equilibrium in an invariant pattern of the “Maxwellian distribution”, which in turn leads to macroscopic properties. However, such an approach is not generally applicable to a nonequilibrium process except in the near-equilibrium realm. To adequately address these drawbacks, steepest-entropy-ascent quantum thermodynamics (SEAQT) provides a first principle, thermodynamic-ensemble approach applicable to the entire nonequilibrium realm. Based on prior developments by the authors, this paper applies the SEAQT framework to modeling the nonquasi-equilibrium cycle, which a system with variable volume undergoes. Using the concept of hypoequilibrium state and nonequilibrium intensive properties, this framework provides a complete description of the nonequilibrium evolution in state of the system. Results presented here reveal how nonequilibrium effects influence the performance of the cycle. - Highlights: • First-principles nonequilibrium model of thermodynamic cycles. • Study of thermal efficiency losses due to nonequilibrium effects. • Study of systems undergoing nonquasi-equilibrium processes. • Study of the coupling of system relaxation and interaction with a reservoir.

  4. The extension of Ubungo power plant in Dar es Salaam, Tanzania, to a combined cycle - A prestudy

    Energy Technology Data Exchange (ETDEWEB)

    Grinneland, L; Oehrstroem, K

    1996-05-01

    The report deals with the consequences concerning a future extension of Ubungo Power Plant. Today the power plant consists of four gas turbines, two of model General Electric LM6000 and two of model ABB Stal GT10 of which the latter were the ones focused on. In the report four different applications are presented; Simple two pressure system, Two pressure system with reheat, Two pressure system with heat exchange between feedwater and condensate, and single pressure system with an additional evaporating loop. The calculations are divided into three sections; thermodynamic calculations, calculations of the heat exchanger surface areas, and economic calculations. From the thermodynamic calculations the applications with the highest thermal efficiency was selected. The power output increased with about 55% and the thermal efficiency of the complete combined cycle is 48.2%. This is, of course, a theoretical value calculated without consideration to a number of losses that will decrease both the power output and the thermal efficiency. At part load (50% load assumed, i.e. one gas turbine is operating) the thermal efficiency is 46.7%. The economic calculations indicated that the extension is highly worthwhile in an economic point of view; both cases studied have a payback time of less than six years for full load operation, provided that the charging system which is to be imposed by the World Bank has come into force. 18 refs, 33 figs

  5. Organics in the power plant cycle. An EPRI perspective

    Energy Technology Data Exchange (ETDEWEB)

    Mathews, James A. [EPRI, Charlotte, NC (United States)

    2008-11-15

    Irrespective of past practices and prejudices, the use of organic treatment chemicals to address new and ongoing concerns in the operation of power plant cycles is increasing. Electric Power Research Institute (EPRI) guidelines currently do not advocate the use of organic additives, citing that these additives should not be needed and that breakdown products pose problems with analytical measurement of cation conductivity and operation of condensate polishers. Some of the concerns about organic treatment are hidden in the association of ''organics'' with naturally occurring organic compounds from contamination sources such as cooling water, lubrication systems, or make-up water treatment and cleaning agents. However, conditions in the 2-phase fluid regions of low pressure heat recovery steam generators (HRSGs), feedwater heaters, the turbine phase transition zone (PTZ), and air-cooled condensers remain problematic and warrant investigation of conditioning with some complex amine type organic treatments. Nuclear plants have employed advanced organic amines such as ethanolamine to address concerns of low pH in condensing steam. Increasing understanding of the formation, morphology and dynamics of boiler deposits may demonstrate the capability to modify the deposit nature and restrict the accumulation of contaminants; what role potential organic treatments may have in this is unclear at this time. The aim of EPRI in the assessment of organics in the fossil power plant cycle is to accomplish a greater understanding of the role, risks and benefits of organic treatment and to more fully engage the technical community in adoption of best practices for the optimum use of these treatments. (orig.)

  6. Brayton-