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Sample records for absorption refrigeration cycle

  1. Conceptual design of an advanced absorption cycle: the double-effect regenerative absorption refrigeration cycle

    Dao, K.

    1978-09-01

    An advanced absorption refrigeration cycle was proposed as a heat-activated refrigeration system. Referred to as the double-effect regenerative absorption cycle of cycle 2R, it improves the performance of the conventional single-effect absorption cycle at high heat source temperatures. The performance of cycle 2R continually improves as input temperatures rise, in contrast to the conventional double-effect absorption cycle that has a sharp cut-off temperature below which it ceases to operate. Cycle 2R operates with two subcycles, the first-effect and the second-effect subcycles.

  2. Investigation of ejector re-compression absorption refrigeration cycle

    Wu, Shenyi

    1999-01-01

    This thesis describes a theoretical and experimental investigation of the ejector re-compression lithium bromide absorption refrigeration cycle. In this novel cycle, a steam ejector is used to enhance the concentration process by compressing the vapour to a state that it can be used to re-heat the solution from where it was evolved. Since this cycle recovers the heat otherwise wasted in a conventional absorption cycle, the energy performance of the cycle is improved. The theoretical study sho...

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

    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.

  4. INJECTING ABSORPTION REFRIGERATION CYCLE%引射吸收式制冷循环

    苏芬仙; 敖越; 等

    2001-01-01

    提出了引射吸收式制冷循环。它可以强化吸收,而且可以扩大吸收式制冷的应用领域。分析了引射吸收式制冷循环,提出了参数选择方法,分析了影响引射式吸收制冷循环中吸收过程的因素并与喷淋吸收过程进行了比较。%A new injecting absorption refrigeration cycle is put forward.The new refrigeration cycle can consolidate absorption of the absorption process and at the same time,the absorption refrigeration cycle can be used in more areas.The new refrigeration cycle is analyzed.A method of choosing the parameters is given.The factors are decribed which affect the absorption process.A comparison with the traditional absorption process is also made.

  5. Optimal Cooling Load and COP Relationship of a Four-Heat-Reservoir Endoreversible Absorption Refrigeration Cycle

    Chih Wu

    2004-06-01

    Full Text Available Abstract: On the basis of a four-heat-reservoir endoreversible absorption refrigeration cycle model, another linear heat transfer law [i.e., the heat-flux] is adopted, the fundamental optimal relation between the coefficient of performance (COP and the cooling load, as well as the maximum cooling load and the corresponding COP of the cycle coupled to constant-temperature heat reservoirs are derived by using finite-time thermodynamics or thermodynamic optimization. The optimal distribution of the heat-transfer surface areas is also obtained. Moreover, the effects of the cycle parameters on the COP and the cooling load of the cycle are studied by detailed numerical examples. The results obtained herein are of importance to the optimal design and performance improvement of an absorption refrigeration cycle.

  6. Optimal Cooling Load and COP Relationship of a Four-Heat-Reservoir Endoreversible Absorption Refrigeration Cycle

    Chih Wu; Fengrui Sun; Tong Zheng; Lingen Chen

    2004-01-01

    Abstract: On the basis of a four-heat-reservoir endoreversible absorption refrigeration cycle model, another linear heat transfer law [i.e., the heat-flux] is adopted, the fundamental optimal relation between the coefficient of performance (COP) and the cooling load, as well as the maximum cooling load and the corresponding COP of the cycle coupled to constant-temperature heat reservoirs are derived by using finite-time thermodynamics or thermodynamic optimization. The optimal distribution of...

  7. Exergo-economic analysis of a solar driven hybrid storage absorption refrigeration cycle

    Highlights: • Exergo-economic analysis for solar-powered hybrid storage absorption system is done. • Pump, SHX and generator have higher exergetic efficiencies than other components. • Initial cost of evaporator and generator should be reduced even at the expense of irreversibilities. • Irreversibilities cost in SHX should be reduced even at the expense of its initial cost. - Abstract: This paper presents the exergo-economic analysis of a 5 kW refrigeration cycle with hybrid storage system. The novel hybrid storage comprises a cold (ice) storage tank, an ammonia storage tank, a weak solution tank and a strong solution tank to suffice the nighttime cooling load. The exergo-economic analysis is performed to compare the components of the refrigeration cycle based on the costs of initial capital investment and the costs of irreversibilities. The components of the refrigeration cycle are evaluated and compared using exergo-economic variables such as the relative cost difference, exergy destruction cost rate and exergo-economic factor. The effect of generator temperature, condenser temperature and evaporator temperature on the exergetic efficiency of the system is also studied. The paper also presents a quasi-steady exergy and exergo-economic analysis for a representative summer day of Dhahran region. This study can be further used in the optimization of design variables of the studied refrigeration cycle

  8. Intermittent Solar Ammonia Absorption Cycle (ISAAC) refrigeration for lesser developed countries

    Erickson, Donald C.

    1990-02-01

    The Intermittent Solar Ammonia Absorption Cycle (ISAAC) refrigerator is a solar thermal technology which provides low cost, efficient, reliable ice-making to areas without ready access to electricity. An ISAAC refrigeration system consists of a compound parabolic solar collector, two pressure vessels, a condenser, a cold box or refrigerated space, and simple connective piping -- no moving parts or electrical components. Most parts are simple construction or plumbing grade materials, locally available in many remote areas. This technology has numerous potential benefits in lesser developed countries both by providing a cheap, reliable source of ice, and, since manufacture requires only semi-skilled labor, a source of employment to the local economy. Applications include vaccine storage for health care clinics; fish, meat, and dairy product storage; and personal consumption. Importantly, this technology increases the quality of life for people in lesser developed countries without depleting fossil fuel resources or increasing the release of greenhouse gases such as CO2 and chlorofluorocarbons.

  9. A novel absorption refrigeration cycle for heat sources with large temperature change

    To increase the use efficiency of available thermal energy in the waste gas/water, a novel high-efficient absorption refrigeration cycle regarded as an improved single-effect/double-lift configuration is proposed. The improved cycle using an evaporator/absorber (E/A) promotes the coefficient of performance and reduces the irreversible loss. Water–lithium bromide is used as the working pair and a simulation study under the steady working conditions is conducted. The results show that the temperature of waste gas discharged is about 20 °C lower than that of the conventional single-effect cycle and the novel cycle we proposed can achieve more cooling capacity per unit mass of waste gas/water at the simulated working conditions. -- Graphical abstract: Pressure – temperature diagram for water – lithium bromide. Highlights: ► A novel waste heat-driven absorption refrigeration cycle is presented. ► The novel cycle can reject heat at much lower temperature. ► The available temperature range of heat source of the proposed cycle is wider. ► Multiple heat sources with different temperatures can be used in the novel cycle

  10. Standard GAX versus hybrid GAX absorption refrigeration cycle: From the view point of thermoeconomics

    Highlights: • The SGAX cycle is found to be thermoeconomically efficient compared to HGAX cycle. • The HGAX cycle has higher COP and exergy efficiency compared to SGAX cycle. • Minimum product cost is found 180.5 $/GJ and 159.1 $/GJ for HGAX and SGAX, respectively. - Abstract: The main goal of this research is to compare thermoeconomic performance of a GAX absorption cycle and a hybrid GAX absorption cycle in which a compressor is employed to raise the absorber pressure. In order to do this, the ammonia–water standard GAX (SGAX) and hybrid GAX (HGAX) absorption refrigeration cycles are investigated and optimized from the viewpoints of thermodynamics and economics. Parametric studies are carried out and with the help of genetic algorithm (GA), the cycles’ performance is optimized based on the COP and exergy efficiency as well as the cost of unit product. Results indicate that although, compared to the GAX cycle, the HGAX cycle demonstrates a better performance from the view points of both the first and second laws of thermodynamics, the unit product cost for the HGAX cycle is higher. At the optimum operating conditions, the cost of unit product for the HGAX cycle is calculated as 180.5 $/GJ while the corresponding value for the SGAX cycle is obtained as 159.1 $/GJ. Also, the exergoeconomic analyses unfold that the condenser has the lowest exergoeconomic factor, f, in both the systems. In addition, inspired from nature, a new graphical plot is proposed to illustrate the fuel cost, product cost, capital investment and operating and maintenance cost and cost rates associated with the exergy destruction and losses within the system’s components

  11. Seven-effect absorption refrigeration

    DeVault, Robert C.; Biermann, Wendell J.

    1989-01-01

    A seven-effect absorption refrigeration cycle is disclosed utilizing three absorption circuits. In addition, a heat exchanger is used for heating the generator of the low absorption circuit with heat rejected from the condenser and absorber of the medium absorption circuit. A heat exchanger is also provided for heating the generator of the medium absorption circuit with heat rejected from the condenser and absorber of the high absorption circuit. If desired, another heat exchanger can also be provided for heating the evaporator of the high absorption circuit with rejected heat from either the condenser or absorber of the low absorption circuit.

  12. Thermodynamic analysis of a novel air-cooled non-adiabatic absorption refrigeration cycle driven by low grade energy

    Graphical abstract: To improve the performance of the air-cooled type absorption refrigeration, a novel non-adiabatic absorber has been applied in the cycle. Simulation results show that low grade energy is applicable for NH3/NaSCN and NH3/LiNO3 absorption refrigeration system under air cooling condition and relatively high system performance can be obtained. - Highlights: • We analyze an absorption refrigeration cycle driven by low grade energy. • Working fluids thermophysical property correlations are corrected. • Influence of non-adiabatic absorber on system performance is investigated. • We propose system operation parameters under air-cooled condition. - Abstract: An air-cooled type absorption refrigeration cycle using ammonia–lithium nitrate and ammonia–sodium thiocyanate solutions as working fluids are thermodynamically studied in this paper. In the case of many occasions especially small cooling capacity occasion where water cooling is restricted or inconvenient, application of conventional adiabatic absorbers in air-cooled type absorption refrigeration system has been studied by many investigators. Comparing to the adiabatic absorber, a novel air-cooled non-adiabatic absorber is applied to the absorption refrigeration system in this study to improve system performance. It is shown that, system performance has a significant improvement when temperatures of rich ammonia solution at the outlet of absorber decrease under the effect of the heat dissipation capacity of the non-adiabatic absorber. Another advantage is that heat load of the system heat exchangers including generator, solution heat exchanger and air-cooler, decreases with the solution temperature decrease at the outlet of the absorber under the same system cooling capacity condition, which brings benefits to the system cost reduction. Variation of system performance and other system operation parameters with generator temperature, absorption temperature and absorption efficiency has

  13. Analysis of ammonia/water and ammonia/salt mixture absorption cycles for refrigeration purposes in fishing ships

    In this work, the use of waste heat energy of jacket water in diesel engines of fishing ships was analysed for use as a heat source for absorption refrigeration systems. The thermodynamic simulation of an absorption refrigeration cycle with three different working fluid mixtures that use ammonia as a refrigerant was carried out. This analysis was assessed in terms of the cooling demand and cycle performance as a function of the evaporator, condenser and generator temperatures. Moreover, the need for rectifying the vapour stream leaving the generator was analysed together with the drag of the fraction of non-evaporated liquid to the absorber. The results show that the NH3/(LiNO3 + H2O) and NH3/LiNO3 fluid mixtures have higher values of COP as compared to NH3/H2O fluid mixture, the differences being more pronounced at low generation temperatures. If the activation temperature is set to 85 °C, the minimum evaporation temperatures that can be achieved are −18.8 °C for the cycle with NH3/LiNO3, −17.5 °C for the cycle with NH3/(LiNO3 + H2O) cycle and −13.7 °C for the NH3/H2O cycle at a condensing temperature of 25 °C. Also, for the NH3/(LiNO3 + H2O) fluid mixture, it has been demonstrated that the absorption refrigeration cycle can be operated without a distillation column and in this case the water content in the refrigerant stream entering the evaporator is less than 1.5% in weight at the operating conditions selected. - Highlights: •Ammonia absorption systems can provide refrigeration necessities for fishing ships. •Absorption refrigeration systems reduce the energy consumption of fishing ships. •The NH3/(LiNO3 + H2O) mixture is recommended for absorption refrigeration cycles

  14. Recent Refrigeration Cycle Technologies for Household Refrigerators

    Nagatomo, Shigemi

    The household refrigerator is one of the most important and the biggest energy-consuming home appliances. This paper summarize recent refrigeration cycle developments in the field of domestic household refrigerators based on a survey of publications.

  15. Evaluation of ionic liquids as absorbents for ammonia absorption refrigeration cycles using COSMO-based process simulations

    Highlights: • NH3–IL absorption cycles are modeled by COSMO-based Aspen simulations. • Proposed a priori computational approach is validated using experimental data. • Cycle performance was analyzed for conventional and task-specific ILs. • IL solvents with high NH3 absorption capacity improve the cycle performance. • Using IL mixtures is revealed as promising alternative in NH3 absorption applications. - Abstract: COSMO-based process simulations with Aspen Plus/Aspen HYSYS are used, for the first time, to a priori estimate the thermodynamic performance of ammonia absorption refrigeration cycles using ionic liquids as absorbents. This allows not only broadening the criteria set used to select/design ionic liquids with optimized properties to be used in that role, but also evaluating innovative strategies to improve the cycle’s performances. COSMO-RS method provides the information required for both creating the ionic liquid non-database components and specifying the COSMOSAC property model to perform Aspen Plus calculations. The computational procedure used here gives at the same time reasonable good property predictions of the vapor (refrigerant) and the condensed (ammonia + ionic liquid) phases as well as physically consistent estimations of the cycle’s performance under different conditions. Current results agree with those previously reported in the literature for several ionic liquid-based systems taken for comparison. In addition, task-specific ionic liquids, with improved properties for ammonia absorption, and also binary ionic liquid mixtures are considered in the analysis. It is obtained that ionic liquids showing higher ammonia absorption capacity among the considered absorbents simultaneously provide the best cycle’s performances. The cycle performances vary in relatively wide intervals depending on the ammonia concentration in the (refrigerant + absorbent) solutions. This behavior is strongly modulated by the ammonia absorption

  16. Heat driven refrigeration cycle at low temperatures

    HE Yijian; HONG Ronghua; CHEN Guangming

    2005-01-01

    Absorption refrigeration cycle can be driven by low-grade thermal energy, such as solar energy, geothermal energy and waste heat. It is beneficial to save energy and protect environment. However, the applications of traditional absorption refrigeration cycle are greatly restricted because they cannot achieve low refrigeration temperature. A new absorption refrigeration cycle is investigated in this paper, which is driven by low-grade energy and can get deep low refrigeration temperature. The mixture refrigerant R23+R134a and an absorbent DMF are used as its working fluid. The theoretical results indicate that the new cycle can achieve -62℃ refrigeration temperature when the generation temperature is only 160℃. This refrigeration temperature is much lower than that obtained by traditional absorption refrigeration cycle. Refrigeration temperature of -47.3℃ has been successfully achieved by experiment for this new cycle at the generation temperature of 157℃, which is the lowest temperature obtained by absorption refrigeration system reported in the literature up to now. The theoretical and experimental results prove that new cycle can achieve rather low refrigeration temperature.

  17. Study of an ejector-absorption refrigeration cycle with an adaptable ejector nozzle for different working conditions

    Highlights: ► An absorption refrigeration cycle with an ejector device at the absorber inlet is presented. ► This cycle is able to reduce up to 9 °C the temperature of onset of refrigerant generation without extra energy consumption. ► At very low driving temperatures it allows increasing the cooling capacity. ► The ejector device proposed has a partially variable geometry and we study its influence on the cycle performances. -- Abstract: This paper presents a numerical model of an ejector-absorption (single-effect) refrigeration cycle with ammonia–lithium nitrate solution as working fluid, operating under steady-state conditions. In this cycle, the ejector is located at the absorber inlet replacing the solution expansion valve. The liquid–gas ejector entrains refrigerant vapor from the evaporator; this way the absorber pressure becomes higher than the evaporator pressure without any additional energy consumption. The objective of this numerical model is to evaluate the influence of the ejector geometry on the cycle performances and to determine the range of the heat source temperature in which it is convenient to use a practical ejector in the absorption cycle. The simulation is based on UA-ΔTlm models for separate heat transfer regions in a novel implementation using plate-type heat exchangers and this way the results are offered as a function of the external temperatures. This study focuses on evaluating the feasibility of an ejector whose nozzle area is adjustable while the rest of the ejector dimensions are fixed, thus being more feasible than complete variable geometry ejectors. The cycle performance is reported for different mixing tube constant diameters. Results of the simulation show that the use of an ejector allows, among others, to decrease the activation temperature approximately 9 °C in respect to the conventional single-effect absorption cycle and increasing the COP for moderate temperatures. The variable ejector nozzle geometry is of

  18. A CAR AIR-CONDITIONING SYSTEM BASED ON AN ABSORPTION REFRIGERATION CYCLE USING SOLAR ENERGY

    Prakash Kumar; Nitin Kumar; Vinod Sehrawat; Tarun Gupta

    2016-01-01

    The main purpose of this paper is to design and study an environment friendly vapour absorption refrigeration system of 0.2 TR capacity using ammonia (R-717) and water as the working fluids. In sunny days (summer season) vehicles becomes too much warm within a few hours a...

  19. The Quantum Absorption Refrigerator

    Levy, Amikam

    2011-01-01

    A quantum absorption refrigerator driven by noise is studied with the purpose of determining the limitations of cooling to absolute zero. The model consists of a working medium coupled simultaneously to hot, cold and noise baths. Explicit expressions for the cooling power are obtained for Gaussian and Poisson white noise. The quantum model is consistent with the first and second laws of thermodynamics. The third law is quantified, the cooling power Jc vanishes as Jc proportional to Tc^{alpha}, when Tc approaches the absolute zero, where alpha = 2 for a bath with flat spectral density and alpha = 3 for an Ohmic spectral density.

  20. Quantum absorption refrigerator.

    Levy, Amikam; Kosloff, Ronnie

    2012-02-17

    A quantum absorption refrigerator driven by noise is studied with the purpose of determining the limitations of cooling to absolute zero. The model consists of a working medium coupled simultaneously to hot, cold, and noise baths. Explicit expressions for the cooling power are obtained for Gaussian and Poisson white noise. The quantum model is consistent with the first and second laws of thermodynamics. The third law is quantified; the cooling power J(c) vanishes as J(c) ∝ T(c)(α), when T(c)→0, where α=d+1 for dissipation by emission and absorption of quanta described by a linear coupling to a thermal bosonic field, where d is the dimension of the bath. PMID:22401189

  1. Absorption refrigeration cycle applied to offshore platforms; Refrigeracao por absorcao aplicada a plataformas de petroleo

    Ferreira, Maximino Joaquim Pina [KROMAV Engenharia, Rio de Janeiro, RJ (Brazil); Pinto, Luiz Antonio Vaz; Belchior, Carlos Rodrigues Pereira [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE)

    2004-07-01

    To produce cold from the heat seems a task unlikely or even impossible. However, absorption systems produce cooling from heat sources and it exist since the century XIX. In industrial places is very important to improve the energy use, even more in places where the activities involve great costs and incomes. Traditionally the alternatives conflict in the aspects of initial and operational costs. This paper describes the absorption systems operation and its main advantages and disadvantages, when compared to the traditional systems with compressor. The known fact that a vapor compressor system presents larger efficiency is not enough to validate it for all of the applications. In this sense, the initial and operational analysis of the costs of the absorption systems becomes interesting. In spite of, double effect absorption systems are demonstrating the evolution of the absorption cycle in order to obtain better performance. Turbo-generators and Turbo-compressors of the offshore platforms are thermal machines that reject great amount of heat in the exhaust gases. This heat is used for heating of water used in the Process Plant. The processes of separation of the mixture water-oil-gas from the well, for instance, use that heat. Even after the passage of the water in the Plant of Process, the residual heat is still enough for the use in absorption systems. A simulation is done using real data of an offshore platform. Two possible alternatives are compared under technical and economical aspects. Sensibility analysis is also performed in order to verify possible impacts of variations of electric power cost. (author)

  2. Thermodynamical comparison and analysis of electric compression refrigeration cycle and absorption refrigeration cycle%电压缩式制冷循环与吸收式制冷循环的热力学比较分析

    冯丽洁; 付林; 张世钢; 江亿

    2012-01-01

    Applying the exergy efficiency and exergy loss analysis method, calculates and compares the exergy efficiency between the electric compression refrigeration cycle and the single-effect absorption refrigeration cycle and the exergy losses of each part of the two cycles under the typical condition. The results show that the exergy efficiency of the two cycles is basically the same when the generator temperature and the heat source temperature are appropriately selected; most part of exercy losses of the electric compression refrigeration cycle occur in the compressor, and most part of exercy losses of the single-effect absorption refrigeration cycle occur in the absorber and generator. Discusses the improving methods for the two cycles.%采用(火用)效率与炯损失分析方法,计算比较了电压缩式制冷循环与单效吸收式制冷循环的(火用)效率及两种制冷循环在典型工况下各环节的(火用)损失.结果表明,当采用合适的发生器温度和热源温度时,两种制冷循环的(火用)效率基本相同;电压缩式制冷循环的主要(火用)损失发生在压缩机环节,吸收式制冷循环的主要(火用)损失发生在吸收器和发生器.讨论了两种制冷循环的改进途径.

  3. Superfluid thermodynamic cycle refrigerator

    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.

  4. Superfluid thermodynamic cycle refrigerator

    A cryogenic refrigerator cools a heat source by cyclically concentrating and diluting the amount of 3He in a single phase 3He-4He solution. The 3He in superfluid 4He 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 3He at an initial concentration in superfluid 4He is contained in a first variable volume connected to a second variable volume through a superleak device that enables free passage of 4He while restricting passage of 3He. The 3He 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. 12 figs

  5. 一个新的吸收-喷射复合制冷循环%A NOVEL COMBINED EJECTOR-ABSORPTION REFRIGERATION CYCLE

    洪大良; 唐黎明; 邹云霞; 何一坚; 陈光明

    2011-01-01

    提出了一个新的吸收-喷射复合制冷循环.在新循环中,部分冷凝器出口的饱和液态制冷剂被冷剂泵加压到制冷剂在发生温度下对应的饱和压力,这股高压制冷剂液体在一个沸腾器里被加热成饱和高压蒸气后将预热器出口的过热制冷剂蒸气引射到冷凝压力.由于在新循环中发生压力可以比冷凝压力低,因此该系统可以利用较低品位的热量制取低温下的冷量.研究结果表明:新循环可以利用比传统两级吸收式制冷循环温度更低的热源,制取同一温度下的冷量.此外,在蒸发温度或发生温度较低时,新循环的COP比单效循环高得多;当发生温度或蒸发温度较高时,新循环和传统单效循环的COP相同.%To make refrigeration at low temperature with low-grade heat source, a novel combined ejector-absorption refrigeration cycle was proposed in this paper. In the new cycle, part of saturated liquid refrigerant from the condenser was pumped to saturated pressure of the refrigerant at generation temperature. This stream was heated into saturated vapor in a boiler and injected the superheating refrigerant vapor from a preheater to condenser pressure. Since the generation pressure is lower than condenser pressure in the new cycle, the system can make refrigeration at low temperature with low-grade heat source. The research results show that the generation temperature of the new cycle is even lower than that of the conventional two-stage absorption refrigeration cycle to make refrigeration at the same low temperature. In addition, the COP of the new cycle is much higher than that of single-effect cycle at the low refrigeration temperature and generation temperature. If the refrigeration temperature or the temperature of heat source is high enough, the COP of the new cycle is the same as that of the conventional single-effect cycle.

  6. A Cooling System for an Automobile Based on Vapour Absorption Refrigeration Cycle Using Waste Heat of an Engine.

    Satish K. Maurya

    2014-03-01

    Full Text Available Now a days the air conditioning system of cars is mainly uses “Vapour Compression Refrigerant System” (VCRS which absorbs and removes heat from the interior of the car that is the space to be cooled and rejects the heat to atmosphere. In vapour compression refrigerant system, the system utilizes power from engine shaft as the input power to drive the compressor of the refrigeration system, hence the engine has to produce extra work to run the compressor of the refrigerating system utilizing extra amount of fuel. This loss of power of the vehicle for refrigeration can be neglected by utilizing another refrigeration system i.e. a “Vapour Absorption Refrigerant System”. As well known thing about VAS that these machines required low grade energy for operation. Hence in such types of system, a physicochemical process replaces the mechanical process of the Vapour Compression Refrigerant System by using energy in the form of heat rather than mechanical work. This heat obtained from the exhaust of high power internal combustion engines.

  7. Refrigerating engineering

    This book gives a description of refrigerating engineering with introduction of refrigerating, abnormal refrigerating cycle and air compression refrigerator, refrigerant and simple steam compression refrigerating cycle, under-cooling cycle, plank cycle, multi-compression cycle, calculation for compressor and practice process of steam compression refrigerating, heat conduction, heat convection, heat radiation, compressor like booster, oil separator, gas purger, an vaporizer and the low-tension side device, operation of refrigerator, steam blast refrigerator, absorption refrigeration machine and application of refrigerating.

  8. Exergy analysis of a novel air-cooled non-adiabatic absorption refrigeration cycle with NH3–NaSCN and NH3–LiNO3 refrigerant solutions

    Graphical abstract: A methodology based on the second law of thermodynamic has been carried out in the analysis of an air-cooled type ammonia/salt absorption refrigeration system. Simulation results show that Low grade energy is applicable for NH3/NaSCN and NH3/LiNO3 absorption refrigeration system under air cooling condition and relatively high exergetic efficiency can be obtained. - Highlights: • We analyze an absorption refrigeration cycle driven by low grade energy. • Modified Methodology in entropy calculation is presented. • New exergy calculation method of ammonia/salt solution is presented. • Exergy analysis under air-cooled condition is carried out. • Influence of non-adiabatic absorber to exergetic efficiency is analyzed. - Abstract: This paper presents a methodology of exergy analysis for ammonia-lithium nitrate and ammonia-sodium thiocyanate absorption refrigeration cycle which applies a novel air-cooled type non-adiabatic absorber to improve both the coefficient of performance and exegetic efficiency of the system under air cooling condition. A modified entropy calculation method for NH3/NaSCN and NH3/LiNO3 solutions is presented in this literature and different results are obtained comparing to previous research. In addition to the variation of solution temperature and pressure from specific working state to the reference state, the variation of solution concentration, which was always neglected by previous researchers in ammonia/salt solution exergy calculation, has been taken into account while analyzing the least potential of ammonia/salt solution for doing useful work, and a corresponding approach for specific exergy calculation is presented. The effects of generator temperature, absorber outlet temperature, absorber efficiency and other system parameters on system exergetic efficiency have been discussed in this study. Analysis results indicate that relatively high system performance can be obtained by air-cooled type ammonia

  9. Solar heating and cooling with absorption refrigeration

    Montlló Casabayó, Gerard

    2010-01-01

    This project is focused on solar heating and cooling installations that use solar thermal energy to produce heat for domestic hot water or space heating, and cooling for air conditioning through absorption refrigeration cycle. The first part of the project is a literature review of said technology. The main components of such installations are described and results and conclusions from existing installations are reviewed. The second part is focused on designing, modelling and simula...

  10. Quantum-enhanced absorption refrigerators.

    Correa, Luis A; Palao, José P; Alonso, Daniel; Adesso, Gerardo

    2014-01-01

    Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step towards the technological exploitation of autonomous quantum refrigerators. PMID:24492860

  11. Simulation of a new combined absorption-compression refrigeration cycle%一种新型吸收-压缩复合制冷循环模拟

    唐鹏武; 陈光明; 唐黎明; 刘利华

    2011-01-01

    A program compiled by Visual Basic language was used to simulate a new combined absorption-compression refrigeration cycle for performance research, including the effect of generation temperature , evaporation temperature, condensation temperature, heat flux and refrigeration capacity on system performance which was compared with a conventional vapour compression refrigeration cycle. Simulation results show that when generation temperature increases, the coefficient of performance ( COP) of new cycle increases first and then decreases. When evaporation temperature or heat flux increases, the COP of new cycle increases. When condensation temperature or refrigeration capacity increases, the COP of new cycle decreases. Under most simulation conditions, the COP of new cycle can be 10% higher than that of conventional vapour compression refrigeration cycle. The new cycle can not only reduce air conditioning load greatly, but also provide the possibility of efficient utilization of low grade energy such as solar energy.%为了对一种新型吸收-压缩复合制冷循环的性能进行模拟,使用Visual Basic语言自行编制了一个程序.该程序模拟了发生温度、蒸发温度、冷凝温度、加热量、制冷量对系统性能的影响,并将其性能与传统蒸气压缩式制冷循环作了对比.模拟结果表明:当发生温度升高时,新循环的制冷系数先增大后减小;当蒸发温度升高或加热量增大时,新循环的制冷系数增大;当冷凝温度升高或制冷量增大时,新循环的制冷系数减小.在大部分假定工况下,新循环的制冷系数比传统蒸气压缩式循环的高10%以上.新循环的提出不仅能够大幅度减少空调电力负荷,还为太阳能等低品位能源的高效利用提供了可能.

  12. Performance analysis of absorption heat transformer cycles using ionic liquids based on imidazolium cation as absorbents with 2,2,2-trifluoroethanol as refrigerant

    Highlights: • TFE + [emim][BF4] (or [bmim][BF4]) absorption heat transformer cycles are studied. • Influence of various operating conditions on cycle’s performance is investigated. • Performance comparisons with H2O + LiBr and TFE + TEGDME cycles are done. • Enthalpy data for TFE + [emim][BF4] (or [bmim][BF4]) liquid mixtures are calculated. • TFE + [emim][BF4] (or [bmim][BF4]) cycles have higher gross temperature lift (GTL). - Abstract: A detailed thermodynamic performance analysis of a single-stage absorption heat transformer and double absorption heat transformer cycles using new working pairs composed of ionic liquids (1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4])) as absorbent and 2,2,2-trifluoroethanol (TFE) as refrigerant has been studied. Several performance indicators were used to evaluate and compare the performance of the cycles using the TFE + [emim][BF4] and TFE + [bmim][BF4] working pairs with the conventional H2O + LiBr and organic TFE + TEGDME working pairs. The obtained results show that the ionic liquid based working pairs are suitable candidates to replace the conventional H2O + LiBr working pairs in order to avoid the disadvantages associated with it mainly crystallization and corrosion and also they perform better (higher gross temperature lift) than TFE + TEGDME working pair at several operating conditions considered in this work

  13. Quantum-enhanced absorption refrigerators

    Correa, Luis A; Alonso, Daniel; Adesso, Gerardo

    2014-01-01

    Thermodynamics is a branch of science blessed by an unparalleled combination of generality of scope and formal simplicity. Based on few natural assumptions together with the four laws, it sets the boundaries between possible and impossible in macroscopic aggregates of matter. This triggered groundbreaking achievements in physics, chemistry and engineering over the last two centuries. Close analogues of those fundamental laws are now being established at the level of individual quantum systems, thus placing limits on the operation of quantum-mechanical devices. Here we study quantum absorption refrigerators, which are driven by heat rather than external work. We establish thermodynamic performance bounds for these machines and investigate their quantum origin. We also show how those bounds may be pushed beyond what is classically achievable, by suitably tailoring the environmental fluctuations via quantum reservoir engineering techniques. Such superefficient quantum-enhanced cooling realises a promising step t...

  14. A Cooling System for an Automobile Based on Vapour Absorption Refrigeration Cycle Using Waste Heat of an Engine.

    Satish K. Maurya; Saurabh Awasthi

    2014-01-01

    Now a days the air conditioning system of cars is mainly uses “Vapour Compression Refrigerant System” (VCRS) which absorbs and removes heat from the interior of the car that is the space to be cooled and rejects the heat to atmosphere. In vapour compression refrigerant system, the system utilizes power from engine shaft as the input power to drive the compressor of the refrigeration system, hence the engine has to produce extra work to run the compressor of the refrigerating s...

  15. Analysis of crystallization risk in double effect absorption refrigeration systems

    Absorption refrigeration systems are an alternative to vapor compression ones in cooling and refrigeration applications. In comparison with single effect absorption units, double effect systems have improved performance. Also, they are more available commercially than the other multi effect absorption cycles. An important challenge in the operation of such systems is the possibility of crystallization within them. This is especially true in developing air-cooled absorption systems, which are attractive because cooling tower and associated installation and maintenance issues can be avoided. Therefore, distinguishing the working conditions that may cause crystallization can be useful in the design and control of these systems. In this paper a computational model has been developed to study and compare the effects of operating parameters on crystallization phenomena in three classes of double effect lithium bromide-water absorption refrigeration systems (series, parallel and reverse parallel) with identical refrigeration capacities. It is shown that the range of operating conditions without crystallization risks in the parallel and the reverse parallel configurations is wider than those of the series flow system. - Highlights: → We study crystallization of double effect absorption refrigeration systems. → We consider series, parallel and reverse parallel cycles. → We study the effect of operating conditions on crystallization. → We choose optimum distribution ratio for parallel and reverse parallel systems. → Crystallization possibility is low in parallel and reverse parallel cycles.

  16. A class of internally irreversible refrigeration cycles

    Ait-Ali, Mohand A.

    1996-03-01

    A Carnot-like irreversible refrigeration cycle is modelled with two isothermal and two non-adiabatic, irreversible processes. The generic source of internal irreversibility, measured by the Clausius inequality, is a general irreversibility term which could include any heat leaks into the Joule - Thompson expansion valve, the evaporator and compressor cold boxes. This cycle is optimized first for maximum refrigeration power and maximum refrigeration load, then for maximum coefficient of performance. Its performances are compared with those of the endoreversible refrigeration cycle, based on a propane stage of a classical cascade liquefaction cycle example. Both cycle models achieve optimum power and maximum refrigeration load at nearly the same refrigeration temperature, but only the coefficient of performance of the irreversible refrigeration cycle reaches a maximum. Moreover, its prediction of heat conductance allocation between evaporator and condenser appears to be not only more conservative, but also more realistic for actual design considerations of refrigeration cycles.

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

    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

  18. The use of absorption refrigeration systems in combined cycle power plants; Empleo de sistemas de refrigeracion por absorcion en plantas de ciclo combinado

    Romero Paredes, H.; Ambriz, J.J.; Vargas, M.; Godinez, M.; Gomez, F.; Valdez, L.; Pantoja, G. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Departamento de Ingenieria de Procesos e Hidraulica, Mexico D. F. (Mexico)

    1995-12-31

    Day after day the electric power generation tends to be done in the most efficient way in order to diminish the generation costs and the rate of environmental pollution per KWh generated. This paper discusses the application of absorption refrigeration systems for the cooling of the air entering the compressor of a gas turbine in a combined cycle, in order to increase the mass air flow and with it the turbine output. The flows with remanent energy content that are not used in a combined cycle can be used for the operation of the absorption refrigeration system. This way, the required thermal energy for the cooling system is free. With this system it is possible to raise the gas turbine generation output from 5% to 25%. [Espanol] La generacion electrica dia con dia pretende realizarse de la manera mas eficiente posible con el objeto de disminuir los costos de generacion y la tasa de contaminacion ambiental por Kwh generado. En el presente trabajo se introduce la aplicacion de sistemas de refrigeracion por absorcion para el enfriamiento del aire de entrada al compresor de la turbina de gas de un ciclo combinado, con el objeto de aumentar el flujo masico del aire y con ello la potencia de salida de la turbina. Las corrientes con contenido remanente de energia termica que no se usan en una planta de ciclo combinado pueden servir para operar el sistema de refrigeracion por absorcion. De esta manera, la energia termica requerida para el sistema de enfriamiento es gratuita. Con este sistema es posible incrementar la potencia de generacion de la turbina de gas de 5 a 25%.

  19. Artificial neural network analysis of triple effect absorption refrigeration systems

    Hajizadeh Aghdam, A. [Department of Mechanical Engineering, Islamic Azad University (Iran, Islamic Republic of)], email: a.hajizadeh@iaukashan.ac.ir; Nazmara, H.; Farzaneh, B. [Department of Mechanical Engineering, University of Tabriz (Iran, Islamic Republic of)], email: h.nazmara@nioec.org, email: b_farzaneh_ms@yahoo.com

    2011-07-01

    In this study, artificial neural networks are utilized to predict the performance of triple effect series and parallel flow absorption refrigeration systems, with lithium bromide/water as the working fluid. Important parameters such as high generator and evaporator temperatures were varied and their effects on the performance characteristics of the refrigeration unit were observed. Absorption refrigeration systems make energy savings possible because they can use heat energy to produce cooling, in place of the electricity used for conventional vapour compression chillers. In addition, non-conventional sources of energy (such as solar, waste heat, and geothermal) can be utilized as their primary energy input. Moreover, absorption units use environmentally friendly working fluid pairs instead of CFCs and HCFCs, which affect the ozone layer. Triple effect absorption cycles were analysed. Results apply for both series and parallel flow systems. A relative preference for parallel-flow over series-flow is also shown.

  20. Not all counterclockwise thermodynamic cycles are refrigerators

    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.

  1. Thermodynamic Analysis of the Irreversibilities in Solar Absorption Refrigerators

    Emma Berrich Betouche

    2016-03-01

    Full Text Available A thermodynamic analysis of the irreversibility on solar absorption refrigerators is presented. Under the hierarchical decomposition and the hypothesis of an endoreversible model, many functional and practical domains are defined. The effect of external heat source temperature on the entropy rate and on the inverse specific cooling load (ISCL multiplied by the total area of the refrigerator A/Qe are studied. This may help a constructor to well dimension the solar machine under an optimal technico-economical criterion A/Qe and with reasonable irreversibility on the refrigerator. The solar concentrator temperature effect on the total exchanged area, on the technico-economical ratio A/Qe, and on the internal entropy rate are illustrated and discussed. The originality of these results is that they allow a conceptual study of a solar absorption refrigeration cycle.

  2. A numerical investigation of a diffusion-absorption refrigeration cycle based on R124-DMAC mixture for solar cooling

    Ben Ezzine, N.; Garma, R.; Bellagi, A. [U.R. Thermique et Thermodynamique des Procedes Industriels, Ecole Nationale d' Ingenieurs de Monastir, Av. Ibn Jazzar, 5060 Monastir (Tunisia)

    2010-05-15

    Research on new working fluid for uses in absorption systems has been continued. The feasibility of a solar driven DAR using the mixture R124/DMAC as working fluid is investigated by numerical simulation. The cycle is simulated for two cooling medium temperatures, 27 C and 35 C, and four driving heat temperatures in the range [90 C-180 C]. The performance characteristics of this system is analyzed parametrically by computer simulation for a design cooling capacity of 1 kW. The results show that the system performance and the lowest (minimum) evaporation temperature reached are largely dependent upon the absorber efficiency and the driving temperature. It is shown that for solar applications this fluid mixture has a higher COP and may constitute an alternative to the conventional ammonia-water system. (author)

  3. Orthogonal Design for Thermosyphon Operated in Absorption Refrigeration Cycles%小型吸收式制冷热虹吸泵的正交试验设计

    王欣; 杨洪海; 张总辉; 杨丰畅; 叶志秦

    2015-01-01

    Thermosyphon was the core component of mini-type solar absorption refrigerator.Its efficiency decided the perform-ance of mini-type solar absorption refrigerator,and mostly depended on the capability of lift pipe.In this paper,according to the design requirements of lithium bromide absorption refrigeration cycle,thermosyphon theoretical model and performance simulation results,we has designed the experiment device and parts of thermosyphon visualization,successfully build and debug experiment device.Using orthogonal test method research factors such as heat,system pressure and immerson ratio influence on thermal si-phon pump performance,the analysis indicates that for the thermal siphon performance,the most important influencing factor is heat,the secondary factor is system pressure and the immerson ratio has minimal impat.%热虹吸泵是小型无泵溴化锂吸收式制冷机的核心部件,对制冷机的运行及工作性能起关键影响。本文根据溴化锂吸收式制冷循环的设计要求,以热虹吸泵理论模型和性能模拟结果为指导,进行了热虹吸泵沿程加热可视化试验装置的方案设计和部件设计,搭建并调试成功试验装置。采用正交试验法研究加热量、系统压力和沉浸比等因素对热虹吸泵提升性能的影响,分析得知,对于热虹吸泵提升性能影响最大的因素是加热量,次要影响因素是系统压力,沉浸比对其影响最小。

  4. Thermodynamic analysis and comparison of combined ejector–absorption and single effect absorption refrigeration systems

    Highlights: • Ammonia/LiNO3 and ammonia/NaSCN combined ejector–absorption refrigeration cycles are analyzed. • The performance of combined cycles is compared to that of single effect cycles. • Ejector is used to facilitate pressure recovery of the absorber and improve mixing. • For low generator temperatures combined cycles have better performance. • Influence of various operating parameters on performance of cycles is investigated. - Abstract: Alternatives to ammonia/water absorption refrigeration cycles that have no need for purification include ammonia/LiNO3 and ammonia/NaSCN cycles. Similar to the other absorption refrigeration cycles they have low coefficients of performance and exergy efficiencies at low generator temperatures. Combined single effect cycles can reduce this problem. In these cycles the solution expansion valve is replaced with an ejector to allow for pressure recovery from the absorber and to enhance mixing of the weak solution and refrigerant vapor from the evaporator. Simulations are used to examine the influence of various operating parameters on performance and the possibility of crystallization in these cycles, and to compare their performances with single effect cycles. It is shown that the combined cycles have better performance than single effect ones at low generator temperatures

  5. A resorption cycle for the cogeneration of electricity and refrigeration

    Graphical abstract: A novel resorption cycle driven by low grade heat for cogeneration of electricity and refrigeration is studied. The cycle features in high exergy efficiency, very little or no ammonia liquid inside and simple structure. Highlights: ► A resorption cogeneration cycle for electricity and refrigeration is proposed. ► The cycle improved refrigeration COP by 10 times compared with Goswami cycle. ► The highest exergy efficiency of the cogeneration cycle is as high as 0.9. ► The cycle also features in safety and simple structure. - Abstract: This paper describes a novel resorption cycle driven by the low grade heat for the cogeneration of electricity and refrigeration, which is based on ammonia adsorption refrigeration technology. The presented cycle features a variable endothermic process which stands for higher adaptability if compared with the traditional Rankine cycle, very little or no ammonia liquid in the system which is a safety feature, solid adsorbents inside the beds, and simple structure for the fact of no rectifying equipment and circulation pumps required by the working fluids. This cycle can be utilised for the heat source with the temperature higher than 100 °C, and it has an electricity generation exergy efficiency of up to 0.69 and a refrigeration coefficient of performance (COP) of up to 0.77. If compared with the Goswami cycle, which is established based on the absorption Kalina cycle for the cogeneration of electricity and refrigeration, the novel resorption cycle kept the merit of the high exergy efficiency for electricity generation, meanwhile, it overcame the limitation of the low refrigeration coefficient of performance (COP) of Goswami cycle, and improved the COP by 10 times. The optimum overall exergy efficiency is as high as 0.9, which is 40–60% improved compared with the Goswami cycle under the same working conditions

  6. The absorption refrigerator as a thermal transformer

    Herrmann, F [Abteilung fuer Didaktik der Physik, Universitaet Karlsruhe (Germany)

    2009-03-15

    The absorption refrigerator can be considered a thermal transformer, that is, a device that is analogous to the electric transformer. The analogy is based on the correspondence between the extensive quantities, entropy and electric charge and the intensive variables, temperature and electric potential.

  7. The Absorption Refrigerator as a Thermal Transformer

    Herrmann, F.

    2009-01-01

    The absorption refrigerator can be considered a thermal transformer, that is, a device that is analogous to the electric transformer. The analogy is based on the correspondence between the extensive quantities, entropy and electric charge and the intensive variables, temperature and electric potential. (Contains 1 footnote and 6 figures.)

  8. Effect of operating conditions on the performance of the bubble pump of absorption-diffusion refrigeration cycles

    Benhmidene Ali

    2011-01-01

    Full Text Available The mathematical model will be able to predict the operated condition (required tube diameters, heat input and submergence ratio….. That will result in a successful bubble pump design and hence a refrigeration unit. In the present work a one-dimensional two-fluid model of boiling mixing ammonia-water under constant heat flux is developed. The present model is used to predict the outlet liquid and vapor velocities and pumping ratio for different heat flux input to pump. The influence of operated conditions such as: ammonia fraction in inlet solution and tube diameter on the functioning of the bubble pump is presented and discussed. It was found that, the liquid velocity and pumping ratio increase with increasing heat flux, and then it decreases. Optimal heat flux depends namely on tube diameter variations. Vapour velocity increases linearly with increasing heat flux under designed conditions.

  9. Proposal and analysis of a high-efficiency combined desalination and refrigeration system based on the LiBr-H2O absorption cycle-Part 2: Thermal performance analysis and discussions

    This paper continues and concludes the study of the proposed high-efficiency combined desalination and refrigeration system based on the LiBr-H2O absorption cycle introduced in the paper that is Part 1 [Proposal and analysis of a high-efficiency combined desalination and refrigeration system based on the LiBr-H2O absorption cycle--Part 1: System configuration and mathematical model. Energy Convers Manage 2010;52:220-7], in which also the mathematical model and its validation are presented in detail. Specifically, the thermal performance of the proposed ARHP-MEE (absorption refrigeration heat pump integrated with a multi-effect evaporation desalter) system, is analyzed, and a parametric sensitivity analysis and a rough economic evaluation are carried out, to clarify and quantify the performance of this combined refrigeration and water system. Typically, driving steam with saturation pressure of 0.15-0.35 MPa and corresponding saturation temperature of 111.4-138.9 oC is applied to run the system. The combined system has good internal synergy, as demonstrated by an energy saving rate of 42% compared with the separate refrigeration-only and water-only systems in a base-case study. The refrigeration-heat cogenerated ARHP subsystem is the main reason for the synergy, with a coefficient of performance of about 1.6 and exergy efficiency above 60% when driven by 0.25 MPa saturated steam. A rough economic analysis indicates qualitatively that there is no penalty in capital equipment for an ARHP-MEE system when compared with the two single-purpose systems, and the higher energy utilization rate of the system makes the energy/operating cost lower.

  10. Design and Simulation of an Absorption Diffusion Solar Refrigeration Unit

    Chaouachi, B; S. Gabsi

    2007-01-01

    The purpose of this study was the design and the simulation of an absorption diffusion refrigerator using solar as source of energy, for domestic use. The design holds account about the climatic conditions and the unit cost due to technical constraints imposed by the technology of the various components of the installation such as the solar generator, the condenser, the absorber and the evaporator. Mass and energy conservation equations were developed for each component of the cycle and solve...

  11. COMPARISON OF ENERGY AND EXERGY EFFICIENCIES OF ABSORPTION REFRIGERATION SYSTEM WITH MECHANICAL COMPRESSION REFRIGERATION SYSTEM

    YAKAR, Gülay; KARABACAK, Rasim; Burçin DEDA ALTAN

    2005-01-01

    In this study, energy and exergy analysis of absorption refrigeration system using LiBr- water and mechanical compression refrigeration system using R134-a were performed at different evaporation temperatures. The results are presented in tables and figures.

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

    Hossein Rezvantalab; Seyyed Abdolreza Fazeli; Farshad Kowsary

    2011-01-01

    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 ne...

  13. Short Time Cycles of Purely Quantum Refrigerators

    Feldmann, Tova

    2012-01-01

    Four stroke Otto refrigerator cycles with no classical analogue are studied. Extremely short cycle times with respect to the internal time scale of the working medium characterize these refrigerators. Therefore these cycles are termed sudden. The sudden cycles are characterized by the stable limit cycle which is the invariant of the global cycle propagator. During their operation the state of the working medium possesses significant coherence which is not erased in the equilibration segments due to the very short time allocated. This characteristic is reflected in a difference between the energy entropy and the Von Neumann entropy of the working medium. A classification scheme for sudden refrigerators is developed allowing simple approximations for the cooling power and coefficient of performance.

  14. Cooling with solar heat. Absorption refrigerator; Mit Sonnenwaerme kuehlen. Absorptionskaeltemaschine

    Anon.

    2009-04-15

    Absorption and adsorption techniques make it possible to provide cold water at a typical air conditioning level by means of solar heat. Often, absorption refrigerators using lithium bromide dissolved in water as absorption agent and water as refrigerant are used for this purpose. (orig.)

  15. Exergoeconomic Analysis of a Refrigeration Cycle

    Durriye Bilge; Galip Temir

    2004-01-01

    The exergoeconomic theory is applied to a two stage vapour compression refrigeration cycle. An exergy-aided cost analysis, taking into account pressure drops and heat gain/loss for all of the components in the refrigeration system as well as the pipe connections, has been made. Exergoeconomic factors, showing whether the monetary expenditures mostly originate from capital investment and Operating and Maintenance (O&M) costs or from exergy destruction and exergy loss, are found and shown i...

  16. Automotive exhaust gas flow control for an ammonia–water absorption refrigeration system

    A considerable part of the energy generated by an automotive internal combustion engine is wasted as heat in the exhaust system. This wasted heat could be recovered and applied to power auxiliary systems in a vehicle, contributing to its overall energy efficiency. In the present work, the experimental analysis of an absorption refrigeration system was performed. The exhaust system of an automotive internal combustion engine was connected to the generator element of an absorption refrigeration system. The performance of the absorption refrigerator was evaluated as a function of the supplied heat. The use of a control strategy for the engine exhaust gas mass flow rate was implemented to optimize the system. Exhaust gas flow was controlled by step-motor actuated valves commanded by a microcontroller in which a proportional-integral control scheme was implemented. Information such as engine torque, speed, key temperatures in the absorption cycle, as well as internal temperatures of the refrigerator was measured in a transient regime. The results indicated that the refrigeration system exhibited better performance when the amount of input heat is controlled based on the temperature of the absorption cycle generator. It was possible to conclude that, by dynamically controlling the amount of input heat, the utilisation range of the absorption refrigeration system powered by exhaust gas heat could be expanded in order to incorporate high engine speed operating conditions. - Highlights: •An absorption refrigerator was driven by automotive exhaust gas heat. •A system for controlling the refrigeration system heat input was developed. •Excessive exhaust gas heat leads to ineffective operation of the refrigerator. •Control of refrigerator's generator temperature led to better performance. •The use of exhaust gas was possible for high engine speeds

  17. Hierarchical Decomposition Thermodynamic Approach for the Study of Solar Absorption Refrigerator Performance

    Emma Berrich Betouche; Ali Fellah; Ammar Ben Brahim; Fethi Aloui; Michel Feidt

    2016-01-01

    A thermodynamic approach based on the hierarchical decomposition which is usually used in mechanical structure engineering is proposed. The methodology is applied to an absorption refrigeration cycle. Thus, a thermodynamic analysis of the performances on solar absorption refrigerators is presented. Under the hypothesis of an endoreversible model, the effects of the generator, the solar concentrator and the solar converter temperatures, on the coefficient of performance (COP), are presented an...

  18. Coefficient of Performance Enhancement of Refrigeration Cycles

    Eng. Naser R. M. AL-Ajmi

    2015-03-01

    Full Text Available Refrigerator is one of the home appliance utilizing mechanical vapor compression cycle in its process. Performance of the systems become the main issue and many researches are still ongoing to evaluate and improve the efficiency of any used system. Therefore, this paper presents an experimental investigation of the performance of the refrigeration cycles. A small rrefrigerator is used as the test rig. The Coefficient of Performance (COP is studied by using different condenser designs and under varying evaporator loads. Three condenser designs are used in present work. These condensers are regular condenser of domestic refrigerator, condenser with copper plain tubes (Cond.1 and condenser with copper tubes welded with stainless steel flat plate (Cond.2. pressures and temperatures measurements of each point in the refrigeration cycle are collected in order to evaluate the refrigerator performance. The results showed that the average COP of Cond.1 and Cond.2 are increased up to 20 % and 14% respectively more than regular condenser design under no load. The evaporator load effects on the machine performance, where the COP of the machine increases with the increase of the evaporator load.

  19. Thermo-economic optimization of an endoreversible four-heat-reservoir absorption-refrigerator

    Based on an endoreversible four-heat-reservoir absorption-refrigeration-cycle model, the optimal thermo-economic performance of an absorption-refrigerator is analyzed and optimized assuming a linear (Newtonian) heat-transfer law applies. The optimal relation between the thermo-economic criterion and the coefficient of performance (COP), the maximum thermo-economic criterion, and the COP and specific cooling load for the maximum thermo-economic criterion of the cycle are derived using finite-time thermodynamics. Moreover, the effects of the cycle parameters on the thermo-economic performance of the cycle are studied by numerical examples

  20. Design and Simulation of an Absorption Diffusion Solar Refrigeration Unit

    B. Chaouachi

    2007-01-01

    Full Text Available The purpose of this study was the design and the simulation of an absorption diffusion refrigerator using solar as source of energy, for domestic use. The design holds account about the climatic conditions and the unit cost due to technical constraints imposed by the technology of the various components of the installation such as the solar generator, the condenser, the absorber and the evaporator. Mass and energy conservation equations were developed for each component of the cycle and solved numerically. The obtained results showed, that the new designed mono pressure absorption cycle of ammonia was suitable well for the cold production by means of the solar energy and that with a simple plate collector we can reach a power, of the order of 900 watts sufficient for domestic use.

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

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

  2. Combined Cycle for Power Generation and Refrigeration Using Low Temperature Heat Sources

    Vijay Chauhan; P. Anil Kishan; Sateesh Gedupudi

    2014-01-01

    A combined refrigeration and power cycle, which uses ammonia-water as the working fluid, is proposed by combining Rankine and vapour absorption cycles with an advantage of varying refrigeration capacity to power output ratio. The study investigates the usage of low temperature heat sources for the cycle operation. Results of parametric analysis are presented, which show the scope for optimization. Results of thermodynamic optimization of the cycle for second law efficiency performed using gen...

  3. Small quantum absorption refrigerator with reversed couplings.

    Silva, Ralph; Skrzypczyk, Paul; Brunner, Nicolas

    2015-07-01

    Small quantum absorption refrigerators have recently attracted renewed attention. Here we present a missing design of a two-qubit fridge, the main feature of which is that one of the two machine qubits is itself maintained at a temperature colder than the cold bath. This is achieved by "reversing" the couplings to the baths compared to previous designs, where only a transition is maintained cold. We characterize the working regime and the efficiency of the fridge. We demonstrate the soundness of the model by deriving and solving a master equation. Finally, we discuss the performance of the fridge, in particular the heat current extracted from the cold bath. We show that our model performs comparably to the standard three-level quantum fridge and thus appears appealing for possible implementations of nanoscale thermal machines. PMID:26274153

  4. Stirling-Cycle Refrigerator Containing Piezoelectric Pumps

    Jalink, Antony, Jr.; Hellbaum, R. F.

    1995-01-01

    Advanced Stirling-cycle cryogenic apparatus suitable for cooling sensitive infrared detectors to very low temperatures. Working fluid in refrigerator helium. Working fluid compressed and circulated by three piezoelectrically actuated diaphragm pumps offering advantages of greater reliability, relative simplicity, and lower cost.

  5. Performance of an irreversible quantum refrigeration cycle

    He Ji-Zhou; Ouyang Wei-Pin; Wu Xin

    2006-01-01

    A new model of a quantum refrigeration cycle composed of two adiabatic and two isomagnetic field processes is established. The working substance in the cycle consists of many non-interacting spin-1/2 systems. The performance of the cycle is investigated, based on the quantum master equation and semi-group approach. The general expressions of several important performance parameters, such as the coefficient of performance, cooling rate, and power input, are given. It is found that the coefficient of performance of this cycle is in the closest analogy to that of the classical Carnot cycle. Furthermore, at high temperatures the optimal relations of the cooling rate and the maximum cooling rate are analysed in detail. Some performance characteristic curves of the cycle are plotted, such as the cooling rate versus the maximum ratio between high and low "temperatures" of the working substances, the maximum cooling rate versus the ratio between high and low "magnetic fields" and the "temperature" ratio between high and low reservoirs. The obtained results are further generalized and discussed, so that they may be directly applied to describing the performance of the quantum refrigerator using spin-J systems as the working substance. Finally, the optimum characteristics of the quantum Carnot and Ericsson refrigeration cycles are derived by analogy.

  6. Energy and Exergy Analysis of Vapour Absorption Refrigeration Cycle—A Review

    Kanabar, Bhaveshkumar Kantilal; Ramani, Bharatkumar Maganbhai

    2016-02-01

    In recent years, an energy crisis and the energy consumption have become global problems which restrict the sustainable growth. In these scenarios the scientific energy recovery and the utilization of various kinds of waste heat become very important. The waste heat can be utilized in many ways and one of the best practices is to use it for vapour absorption refrigeration system. To ensure efficient working of absorption cycle and utilization of optimum heat, exergy is the best tool for analysis. This paper provides the comprehensive picture of research and development of absorption refrigeration technology, practical and theoretical analysis with different arrangements of the cycle.

  7. Energy and Exergy Analysis of Vapour Absorption Refrigeration Cycle—A Review

    Kanabar, Bhaveshkumar Kantilal; Ramani, Bharatkumar Maganbhai

    2016-07-01

    In recent years, an energy crisis and the energy consumption have become global problems which restrict the sustainable growth. In these scenarios the scientific energy recovery and the utilization of various kinds of waste heat become very important. The waste heat can be utilized in many ways and one of the best practices is to use it for vapour absorption refrigeration system. To ensure efficient working of absorption cycle and utilization of optimum heat, exergy is the best tool for analysis. This paper provides the comprehensive picture of research and development of absorption refrigeration technology, practical and theoretical analysis with different arrangements of the cycle.

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

    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.

  9. Exergoeconomic Analysis of a Refrigeration Cycle

    Durriye Bilge

    2004-01-01

    Full Text Available The exergoeconomic theory is applied to a two stage vapour compression refrigeration cycle. An exergy-aided cost analysis, taking into account pressure drops and heat gain/loss for all of the components in the refrigeration system as well as the pipe connections, has been made. Exergoeconomic factors, showing whether the monetary expenditures mostly originate from capital investment and Operating and Maintenance (O&M costs or from exergy destruction and exergy loss, are found and shown in the form of tables. The true cost of the heat drawn from cold room, which is the product of a refrigeration sytem, has been calculated. In this way, it will be possible to reflect the cost of cold room storage to the market price of the goods completely and precisely.

  10. COMPARISON OF ENERGY AND EXERGY EFFICIENCIES OF ABSORPTION REFRIGERATION SYSTEM WITH MECHANICAL COMPRESSION REFRIGERATION SYSTEM

    Gülay YAKAR

    2005-02-01

    Full Text Available In this study, energy and exergy analysis of absorption refrigeration system using LiBr- water and mechanical compression refrigeration system using R134-a were performed at different evaporation temperatures. The results are presented in tables and figures.

  11. A Cold Cycle Dilution Refrigerator for Space Applications Project

    National Aeronautics and Space Administration — The cold cycle dilution refrigerator is a continuous refrigerator capable of cooling to temperatures below 100 mK that makes use of a novel thermal magnetic pump....

  12. Modelling and data validation for the energy analysis of absorption refrigeration systems

    Martínez Maradiaga, David Estéfano

    2013-01-01

    Data validation and reconciliation techniques have been extensively used in the process industry to improve the data accuracy. These techniques exploit the redundancy in the measurements in order to obtain a set of adjusted measurements that satisfy the plant model. Nevertheless, not many applications deal with closed cycles with complex connectivity and recycle loops, as in absorption refrigeration cycles. This thesis proposes a methodology for the steady-state data validation of absorption ...

  13. An innovative ecological hybrid refrigeration cycle for high power refrigeration facility

    Cyklis Piotr; Janisz Karina

    2015-01-01

    Searching for new refrigerants is one of the most significant scientific problems in refrigeration. There are ecological refrigerants commonly known: H2O and CO2. H2O and CO2 known as natural refrigerants, but they have problems:a high freezing point of H2O and a low triple point of CO2. These problems can be solved by the application of a hybrid sorption-compression refrigeration cycle. The cycle combines the application possibility of H2O in the high temperature sorption stage and the low t...

  14. PECULIARITIES OF THE IDEALIZED CYCLES OF VAPOR COMPRESSOR REFRIGERATING MACHINES

    Вассерман, А. А.; Лавренченко, Г. К.; Слынько, А. Г.

    2014-01-01

    Efficiency of the idealized cycles of vapor compressor refrigerating machines with adiabatic or isothermal compression of refrigerantwas investigated. To these cycles concern cycles with adiabatic compression of steam without regeneration (S-cycle) and with limiting regeneration (SR-cycle), and also with isothermal compression and limiting regeneration (T-cycle). Three characteristics of cycles are compared: refrigerating coefficient of performance e, specific-volume cooling capacity qv and t...

  15. Transitions between refrigeration regions in extremely short quantum cycles

    Feldmann, Tova; Kosloff, Ronnie

    2016-05-01

    The relation between the geometry of refrigeration cycles and their performance is explored. The model studied is based on a coupled spin system. Small cycle times, termed sudden refrigerators, develop coherence and inner friction. We explore the interplay between coherence and energy of the working medium employing a family of sudden cycles with decreasing cycle times. At the point of maximum coherence the cycle changes geometry. This region of cycle times is characterized by a dissipative resonance where heat is dissipated both to the hot and cold baths. We rationalize the change of geometry of the cycle as a result of a half-integer quantization which maximizes coherence. From this point on, increasing or decreasing the cycle time, eventually leads to refrigeration cycles. The transition point between refrigerators and short circuit cycles is characterized by a transition from finite to singular dynamical temperature. Extremely short cycle times reach a universal limit where all cycles types are equivalent.

  16. Thermodynamic Analysis of the Irreversibilities in Solar Absorption Refrigerators

    Emma Berrich Betouche; Ali Fellah; Ammar Ben Brahim; Fethi Aloui; Michel Feidt

    2016-01-01

    A thermodynamic analysis of the irreversibility on solar absorption refrigerators is presented. Under the hierarchical decomposition and the hypothesis of an endoreversible model, many functional and practical domains are defined. The effect of external heat source temperature on the entropy rate and on the inverse specific cooling load (ISCL) multiplied by the total area of the refrigerator A/Qe are studied. This may help a constructor to well dimension the solar machine under an optimal tec...

  17. Closed cycle refrigeration for routine magnetotransport measurements

    Gunawardana, Binuka; Ye, Tianyu; Wegscheider, Werner; Mani, Ramesh

    2015-03-01

    Condensed matter physics is often interested in the behavior of materials at very low temperatures. Low temperatures have traditionally been realized using liquid helium. However, the recent scarcity of liquid helium and the rapid rise in its cost has encouraged the development of alternative approaches, based on closed cycle refrigerators, for realizing low temperatures. Here, we convey our experiences in developing a home-made, low cost, variable temperature closed cycle refrigeration system for routine magnetotransport measurements down to 10K, and present measurements obtained with this system relating to the electronic properties of the high mobility GaAs/AlGaAs 2D semiconductors system. The setup was constructed to examine 0.5cm × 0.5cm semiconductor chips including up to 49 leads and reach ~ 10K within 3 hours. A computer controlled data acquisition system was assembled to collect resistivity and Hall effect data, and extract the carrier Hall mobility and density as a function of the temperature.

  18. Research on performance of mixed absorption refrigeration for solar air-conditioning

    2008-01-01

    A novel lithium bromide/water mixed absorption refrigeration cycle that is suitable for the utilization of solar air-conditioning and can overcome the drawbacks of low system overall efficiency of traditional solar absorption refrigeration air-condition systems is presented.The accessorial high pressure generator was added in the cycle.The lithium bromide solution flowing out from the high pressure generator was mixed with the solution from the low pressure absorber to increase lithium bromide solution concentration and decrease pressure in the high pressure absorber.The performance of a mixed absorption refrigeration cycle was analyzed.The theoretical analysis shows that the highest COP is 0.61,while the highest available temperature difference of heat resource is 33.2℃.The whole coefficient of performance of the solar air-conditioning using mixed absorption cycle is 94.5% higher than that of two-stage absorption.The advantages of solar air-conditioning can be markedly made use of by the cycle.

  19. Research on a New Type of Solar-driven Air-cooled NH3H2O Absorption Refrigeration Cycle%新型太阳能风冷氨水吸收式制冷循环的研究

    任秀宏; 王林

    2012-01-01

    A new type of solar-driven air-cooled NH3H2O absorption refrigeration cycle was proposed. It have rectification e-quipment for purifying ammonia steam and recovers heat from rectifier and absorber. By these realizing small size, air - cooled and the effective use of solar energy. So the coefficient of performance (COP) is increased compared with traditional models. Based on energy conservation, solution mass conservation and ammonia components mass conservation,the thermodynamic math-ematic model of each component is established. Then cycle performance is calculated by writing programs. The effect of main operation parameters(heat source temperature, evaporating temperature,condensing temperature)on the coefficient of performance ( COP) was studied, laying the foundation for optimization design and operation of refrigeration system.%提出一种新型太阳能风冷氨水吸收式制冷循环系统,该系统设置精馏器提纯氨蒸汽,并有效回收精馏器精馏热及中温吸收器吸收热,实现对太阳能的有效利用以及机组风冷化和小型化,与传统系统相比其系统性能系数(COP)显著提高.基于能量守恒、溶液质量守恒和氨组分质量守恒建立系统各部件热力学数学模型,在此基础上编写程序对系统循环特性进行理论计算,分析热源温度、蒸发温度、冷凝温度等参数对系统COP的影响,为系统优化设计及建立最优运行方案提供理论支持.

  20. Proposal and analysis of a high-efficiency combined desalination and refrigeration system based on the LiBr-H2O absorption cycle-Part 1: System configuration and mathematical model

    Simultaneous production of fresh water and refrigeration are often required, e.g. in warm-climate water-deficient regions, and this study is a proposal and analysis of an efficient way of producing both of them by consuming mainly low-grade heat. After introducing the configuration choice methodology, a combined refrigeration and water system, ARHP-MEE (absorption refrigeration heat pump and multi-effect evaporation desalter), which is the integration of a LiBr-H2O refrigeration unit, a LiBr-H2O heat pump, and a low-temperature multi-effect evaporation desalination unit, is proposed, and the mathematical model is presented and validated. The model serves for conducting a performance analysis of the combined system, reported in Part 2 of this two-part paper.

  1. Performance Enhancement Technology for the Vapor Compression Refrigeration Cycle

    Man'o, Tatsunori

    High efficiency refrigerator have been developed. For energy saving that is concerned with against global warming, performance enhancement of vapor compression refrigerator is required in field of air condition and refrigeration facility. In this paper, a review of recent performance enhancement technologies for the vapor compression refrigeration cycle is presented. This review contains high performance cycles of large sized centrifugal chiller, small to middle sized chiller and packaged air conditioner. Moreover, researches and developments of the refrigeration cycle recovering throttling loss, applications of ejector to boost in compressor suction pressure and to recirculate vapor refrigerant in the evaporator for heat transfer enhancement, and applications of expander to employ expansion work for compression work, are reviewed.

  2. Refrigeration Carnot-type cycle based on isothermal vapour compression

    Meunier, F. [Laboratoire du Froid EA 21, Cnam-IFFI, 292 rue Saint-Martin (France)

    2006-01-01

    A refrigeration Carnot-type cycle based on isothermal compression and two reversible expansions is proposed. Although ideal, this cycle is close to a realistic one which could be designed with existing hardware. (author)

  3. Modeling And Experimental Analysis Of Generator In Vapour Absorption Refrigeration System

    Christy V Vazhappilly

    2013-09-01

    Full Text Available A breadboard prototype of an absorption system for refrigeration using heat from the exhaust-gases is to be designed, built and tested. In the commercial vapour absorption refrigeration system a heating coil generator system has been employed to vaporize the ammonia efrigerant. In the present work, the heating coil generator system has been replaced by the frame plate type heat exchanger. The exhaust gases from the IC engine have been utilized to vaporize the ammonia refrigerant. The available heat in the exhaust gases has to be estimated based on actual I.C-Engine driving cycles. The frame plate type heat exchanger has to be modeled and flow analysis inside the heat exchanger has to be analyzed. In addition, the recoverable energy of the exhaust gases is to be analyzed for representative Internal Combustion Engine.

  4. New Regenerative Cycle for Vapor Compression Refrigeration

    Mark J. Bergander

    2005-08-29

    second step of compression. In the proposed system, the compressor compresses the vapor only to 50-60% of the final pressure, while the additional compression is provided by a jet device using internal potential energy of the working fluid flow. Therefore, the amount of mechanical energy required by a compressor is significantly reduced, resulting in the increase of efficiency (either COP or EER). The novelty of the cycle is in the equipment and in the way the multi-staging is accomplished. The anticipated result will be a new refrigeration system that requires less energy to accomplish a cooling task. The application of this technology will be for more efficient designs of: (1) Industrial chillers, (2) Refrigeration plants, (3) Heat pumps, (4) Gas Liquefaction plants, (5) Cryogenic systems.

  5. Applying design of experiments to a compression refrigeration cycle

    Nuno Ricardo Costa

    2015-12-01

    Full Text Available Refrigeration cycles are used in a large diversity of industrial and domestic (residential and non-residential equipment and their efficiency depend on several variables. To better understanding of how controllable variables impact on a compression refrigeration cycle efficiency, statistically designed experiments were conducted and data were analyzed. A quadratic polynomial model was fitted to Coefficient of Performance and variable settings to maximize cycle efficiency identified. Results give confidence to use the illustrated approach for refrigeration cycle design and operation improvement purposes.

  6. Cavity-enhanced absorption for optical refrigeration

    Seletskiy, Denis V; Sheik-Bahae, Mansoor

    2009-01-01

    A 20-fold increase over the single path optical absorption is demonstrated with a low loss medium placed in a resonant cavity. This has been applied to laser cooling of Yb:ZBLAN glass resulting in 90% absorption of the incident pump light. A coupled-cavity scheme to achieve active optical impedance matching is analyzed.

  7. Modelling of the generation phase of an absorption cooling cycle operating intermittently; Modelisation de la phase generation d'un cycle de refrigeration par absorption solaire a fonctionnement intermittent

    Boukhchana, Yasmina; Fellah, Ali; Ben Brahim, Ammar [Unite de Recherche, Thermodynamique Appliquee (99/UR/11-21), Universite de Gabes, Ecole Nationale d' ingenieurs, 6072 Gabes (Tunisia)

    2011-01-15

    No abstract prepared. [French] La modelisation en regime dynamique de la phase generation d'une installation frigorifique a absorption solaire a fonctionnement intermittent utilisant le couple ammoniac/eau a ete elaboree. L'etude basee sur l'intermittence du fonctionnement a permis d'elaborer, a travers les bilans matieres et thermiques, un modele thermodynamique reliant les temperatures, les debits et les fractions massiques dans les differents compartiments. Des journees ensoleillees representatives des quatre saisons de l'annee ont ete considerees. Les variations du taux d'ensoleillement, des temperatures et des concentrations ont ete explorees. Les resultats ont montre, moyennant les hypotheses adoptees en particulier a pression de fonctionnement constante, que la demarche proposee a permis d'avoir une temperature de generation autour de 135 C et une temperature de condensation de 60 C. Ces temperatures sont atteinte par l'adaptation de la convection naturelle a l'air pour le fonctionnement du condenseur. (orig.)

  8. Optimization of a solar driven absorption refrigerator in the transient regime

    Highlights: ► Dynamic behavior of a solar absorption refrigerator endoreversible model. ► Using the principles of classical thermodynamics, mass and heat transfers. ► Minimizing heat exchange time to reach maximum performances. ► Major influence of the collector temperature on the model’s characteristics. ► Analogous effects of both the thermal load and the thermal conductance. -- Abstract: This contribution deals with the theoretical study in dynamic mode of an absorption refrigerator endoreversible model. The system is a cold generating station driven by solar energy. The main elements of the cycle are a refrigerated space, an absorption refrigerator and a solar collector form. A mathematical model is developed. It combines the classical thermodynamics and mass and heat transfers principles. The numerical simulation is made for different operating and conceptual conditions. A global minimizing time optimization is performed in view to reach maximum performances. Appropriate dimensionless groups are defined. The results are presented in normalized charts for general applications. The collector temperature presents major influence on the conceptual and functional characteristics compared to the stagnation temperature influence. On the other hand the thermal load in the refrigerated space and the thermal conductance of the walls has analogous effects, therefore important to be considered in actual design. As a result, the model is expected to be a useful tool for simulation, design, and optimization of solar collector based energy systems.

  9. Experimental Investigation on an Absorption Refrigerator Driven by Solar Cells

    Zi-Jie Chien

    2013-01-01

    Full Text Available This experiment is to study an absorption refrigerator driven by solar cells. Hand-held or carried in vehicle can be powered by solar energy in places without power. In the evenings or rainy days, it is powered by storage battery, and it can be directly powered by alternating current (AC power supply if available, and the storage battery can be charged full as a backup supply. The proposed system was tested by the alternation of solar irradiance 550 to 700 W/m2 as solar energy and 500ml ambient temperature water as cooling load. After 160 minutes, the proposal refrigerator can maintain the temperature at 5–8°C, and the coefficient of performance (COP of NH3-H2O absorption refrigeration system is about 0.25. Therefore, this system can be expected to be used in remote areas for refrigeration of food and beverages in outdoor activities in remote and desert areas or long-distance road transportation of food or low temperature refrigeration of vaccine to avoid the deterioration of the food or the vaccines.

  10. Refrigeration Cycle Design for Refrigerant Mixtures by Molecular Simulation

    Smith, W.R.; Francová, Magda; Kowalski, M.; Nezbeda, Ivo

    2010-01-01

    Roč. 75, č. 4 (2010), s. 383-391. ISSN 0010-0765 R&D Projects: GA AV ČR IAA400720710 Grant ostatní: NSERC(CA) OGP1041 Institutional research plan: CEZ:AV0Z40720504 Keywords : refrigerants * molecular simulations * vapor–liquid equilibrium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.853, year: 2010

  11. Applying design of experiments to a compression refrigeration cycle

    Nuno Ricardo Costa; João Garcia

    2015-01-01

    Refrigeration cycles are used in a large diversity of industrial and domestic (residential and non-residential) equipment and their efficiency depend on several variables. To better understanding of how controllable variables impact on a compression refrigeration cycle efficiency, statistically designed experiments were conducted and data were analyzed. A quadratic polynomial model was fitted to Coefficient of Performance and variable settings to maximize cycle efficiency identified. Results ...

  12. Theoretical study on a novel dual-nozzle ejector enhanced refrigeration cycle for household refrigerator-freezers

    Highlights: • A novel dual-nozzle ejector enhanced refrigeration cycle is proposed. • The novel cycle is evaluated by using the developed mathematical model. • The results show the performances of the novel cycle could be significantly improved. • The novel cycle shows its promise in household refrigerator-freezers applications. - Abstract: In this study, a novel dual-nozzle ejector enhanced refrigeration cycle is presented for dual evaporator household refrigerator-freezers. The proposed ejector equipped with two nozzles can efficiently recover the expansion work from cycle throttling processes and enhance cycle performances. The performances of the novel cycle are evaluated by using the developed mathematical model, and then compared with that of the conventional ejector enhanced refrigeration cycle and basic vapor-compression refrigeration cycle. The simulation results show that for the given operating conditions, the coefficient of performance (COP) of the novel cycle using refrigerant R134a is improved by 22.9–50.8% compared with that of the basic vapor-compression refrigeration cycle, and the COP improvement is 10.5–30.8% larger than that of the conventional ejector enhanced refrigeration cycle. The further simulation results of the novel cycle using refrigerant R600a indicate that the cycle COP and volumetric refrigeration capacity could be significantly improved

  13. Absorber-evaporator unit for an absorption-refrigeration system

    Hallatt, R.J.; Rorschach, R.L.

    1965-01-26

    This low temperature absorption-refrigeration system uses an absorber-evaporator. A conduit is connected between the upper portion of the absorber and the lower portion of the evaporator to conduct inert gas from the absorber to the evaporator. A second conduit connects the upper portion of the evaporator to the lower portion of the absorber and a blower in this conduit circulates the inert gas through the closed system. By placing the blower between the evaporator ad the absorber, the pressure in the evaporator is maintained at a minimum so that the working temperature is as low as possible. The medium to be cooled by the refrigerant is circulated through a heat exchanger located within the evaporator, whereby the latent heat of vaporization of the liquid refrigerant is employed to cool the outside medium. (2 claims)

  14. Industrial trigeneration using ammonia-water absorption refrigeration systems (AAR)

    In many industrial processes there is a simultaneous need for electric power and refrigeration at low temperatures. Examples are in the food and chemical industries. Nowadays the increase in fuel prices and the ecological implications are giving an impulse to energy technologies that better exploit the primary energy source and integrated production of utilities should be considered when designing a new production plant. The number of so-called trigeneration systems installations (electric generator and absorption refrigeration plant) is increasing. If low temperature refrigeration is needed (from 0 to -40 deg. C), ammonia-water absorption refrigeration plants can be coupled to internal combustion engines or turbogenerators. A thermodynamic system study of trigeneration configurations using a commercial software integrated with specifically designed modules is presented. The study analyzes and compares heat recovery from the primary mover at different temperature levels. In the last section a simplified economic assessment that takes into account disparate prices in European countries compares conventional electric energy supply from the grid and optimized trigeneration plants in one test case (10 MW electric power, 7000 h/year)

  15. SOLAR MULTI-STAGE ABSORPTION REFRIGERATION SYSTEMS BASED ON FILM TYPE HEAT-MASS EXCHANGE APPARATUSES

    Дорошенко, О.В.; Антонова, А.Р.; Людницький, К.В.

    2015-01-01

    The paper presents the developed circuit solutions for alternative refrigeration systems based on the of heat-absorption cycle and solar energy utilization for regeneration (recovery) of the absorbent solution. Cascade principle of heat-mass exchange apparatuses construction was applied, of drying and cooling loops with varying of  temperature level and increasing  of absorbent concentration on the cascade steps. Film type heat and mass transfer equipment, which is the part of the drying and ...

  16. Modelling and Simulation of a Two-Stage Refrigeration Cycle

    Verheyleweghen, Adriaen

    2015-01-01

    A two-stage refrigeration cycle was modelled and optimized in MATLAB. The optimum was found to be very flat, resulting in small losses from disturbances and implementation errors. The two unconstrained degrees of freedom were used to implement self-optimizing controllers. A subset of five measurements was used for the self-optimizing controller since this gave reasonably small losses. The controllers assured optimal steady-state operation of the refrigeration cycle even when disturbed. Studie...

  17. An innovative ecological hybrid refrigeration cycle for high power refrigeration facility

    Cyklis Piotr

    2015-09-01

    Full Text Available Searching for new refrigerants is one of the most significant scientific problems in refrigeration. There are ecological refrigerants commonly known: H2O and CO2. H2O and CO2 known as natural refrigerants, but they have problems:a high freezing point of H2O and a low triple point of CO2. These problems can be solved by the application of a hybrid sorption-compression refrigeration cycle. The cycle combines the application possibility of H2O in the high temperature sorption stage and the low temperature application of CO2 in the compression stage. This solution gives significant energy savings in comparison with the two-stage compressor cycle and with the one-stage transcritical CO2 cycle. Besides, the sorption cycle may be powered by low temperature waste heat or renewable heat. This is an original idea of the authors. In the paper an analysis of the possible extension of this solution for high capacity industrial refrigeration is presented. The estimated energy savings as well as TEWI (Total Equivalent Warming Impact index for ecological gains are calculated.

  18. A small quantum absorption refrigerator with reversed couplings

    Silva, Ralph; Skrzypczyk, Paul; Brunner, Nicolas

    2015-01-01

    Small quantum absorption refrigerators have recently attracted renewed attention. Here we present a missing design of a two-qubit fridge, the main feature of which is that one of the two machine qubits is itself maintained at a temperature colder than the cold bath. This is achieved by 'reversing' the couplings to the baths compared to previous designs, where only a transition is maintained cold. We characterize the working regime and the efficiency of the fridge. We demonstrate the soundness...

  19. Industrial refrigeration by absorption/compression; Refrigeracion industrial por absorcion/compresion

    Ayala Delgado, Ramon; Heard, Christopher Lionel [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1996-12-31

    The use of the absorption/compression refrigeration in the industrial area is analyzed. It is estimated than in Mexico 50% of the food is wasted for lack of refrigeration in the producing centers and by the inefficient distribution system, as well as for the hot climate. The functioning of the absorption refrigeration and the hybrid system absorption/compression which can operate with the two thermodynamic cycles in variable proportions, depending on the specific application, looking for operational advantages and energy efficiency is described. This type of technology could be applied in Mexico due to the lack of industrial refrigeration and to the need of substituting compressors in some companies which have up to 20 years of use [Espanol] Se analiza el uso de la refrigeracion por absorcion/compresion en el area industrial. En Mexico se estima que se desperdicia el 50% de los alimentos por falta de refrigeracion en los centros productores y por el deficiente sistema de distribucion, asi como por el clima calido. Se describe el funcionamiento de la refrigeracion por absorcion y la refrigeracion por absorcion/compresion o sistema hibrido, el cual puede funcionar con los dos tipos de ciclos termodinamicos, en proporciones variables, dependiendo de la aplicacion especifica, buscando ventajas de operacion y eficiencia energetica. Este tipo de tecnologia podria aplicarse en Mexico debido a la falta de refrigeracion industrial y a la necesidad de sustituir compresores en algunas empresas los cuales tienen hasta 20 anos de uso

  20. Ecological optimization for an irreversible magnetic Ericsson refrigeration cycle

    Wang Hao; Wu Guo-Xing

    2013-01-01

    An irreversible Ericsson refrigeration cycle model is established,in which multi-irreversibilities such as finite-rate heat transfer,regenerative loss,heat leakage,and the efficiency of the regenerator are taken into account.Expressions for several important performance parameters,such as the cooling rate,coefficient of performance (COP),power input,exergy output rate,entropy generation rate,and ecological function are derived.The influences of the heat leakage and the time of the regenerative processes on the ecological performance of the refrigerator are analyzed.The optimal regions of the ecological function,cooling rate,and COP are determined and evaluated.Furthermore,some important parameter relations of the refrigerator are revealed and discussed in detail.The results obtained here have general significance and will be helpful in gaining a deep understanding of the magnetic Ericsson refrigeration cycle.

  1. Ecological optimization for an irreversible magnetic Ericsson refrigeration cycle

    An irreversible Ericsson refrigeration cycle model is established, in which multi-irreversibilities such as finite-rate heat transfer, regenerative loss, heat leakage, and the efficiency of the regenerator are taken into account. Expressions for several important performance parameters, such as the cooling rate, coefficient of performance (COP), power input, exergy output rate, entropy generation rate, and ecological function are derived. The influences of the heat leakage and the time of the regenerative processes on the ecological performance of the refrigerator are analyzed. The optimal regions of the ecological function, cooling rate, and COP are determined and evaluated. Furthermore, some important parameter relations of the refrigerator are revealed and discussed in detail. The results obtained here have general significance and will be helpful in gaining a deep understanding of the magnetic Ericsson refrigeration cycle. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  2. The performance of an open cycle dilution refrigerator

    The idea of an open cycle dilution refrigerator is that two separate flows of 3-helium an 4-helium are mixed at low temperature, overcoming the influence of the gravitation. We have measured the performance of the refrigerator for a high concentration of 3He, where the mixture appears in two phases, and we discuss the possibility of running at a lower concentration (single phase). We discuss the use of such a refrigerator to cool bolometers for telescopes, on earth or in space. (author)

  3. Modeling and Simulation of a Desiccant Assisted Brayton Refrigeration Cycle

    Nobrega, Carlos E.L.; Sphaier, Leandro Alcoforado

    2012-01-01

    The phase-out of CFCs has shed a new light over natural refrigerants, which have null global warming potentials. Air would be a natural choice, and although the Brayton cycle usually exhibits a lower coefficient of performance when compared to vapor-compression systems of same capacity, it has been considered in applications other than aircraft cooling. These include gas separation, food processing and preservation, refrigerated containers and train air-conditioning. Price perspectives in the...

  4. Automated modelling of complex refrigeration cycles through topological structure analysis

    We have developed a computational method for analysis of refrigeration cycles. The method is well suited for automated analysis of complex refrigeration systems. The refrigerator is specified through a description of flows representing thermodynamic sates at system locations; components that modify the thermodynamic state of a flow; and controls that specify flow characteristics at selected points in the diagram. A system of equations is then established for the refrigerator, based on mass, energy and momentum balances for each of the system components. Controls specify the values of certain system variables, thereby reducing the number of unknowns. It is found that the system of equations for the refrigerator may contain a number of redundant or duplicate equations, and therefore further equations are necessary for a full characterization. The number of additional equations is related to the number of loops in the cycle, and this is calculated by a matrix-based topological method. The methodology is demonstrated through an analysis of a two-stage refrigeration cycle.

  5. Thermo-economic analysis of steady state waste heat recovery in data centers using absorption refrigeration

    Highlights: • Absorption refrigeration is powered by data center waste heat. • Waste heat from 3 to 5 server racks produces cooling for an additional rack. • An economic analysis shows the payback period can be as short as 4–5 months. - Abstract: This paper addresses the technical and economic issues associated with waste heat recovery in data centers through the use of absorption cooling machines. The theoretical possibility of utilizing the heat dissipated by a server, or a number of servers, to power an absorption system, which in turn produces cooling for other servers in the data center, is investigated. For this purpose, a steady-state thermodynamic model is developed to perform energy balance and exergy analyses for a novel configuration of an on-chip two-phase cooling system and an absorption refrigeration system. This combination is created by replacing the condenser in the on-chip cooling circuit with the generator of an absorption refrigeration cycle. The performance of the developed model in simulating both LiBr–water and water–ammonia absorption cooling systems is examined through verification of the model results against the reference data available in the literature. The verification indicates the superiority of LiBr–water absorption system for data center/server operating conditions. Therefore, a LiBr–water absorption refrigeration system is modeled in the novel combined heat recovery system. For these systems it is shown that the traditional definition for the coefficient of performance (COP) is not appropriate to evaluate the performance and, in its place, introduce a new figure of merit. Through a sensitivity analysis, the effects of server waste heat quality, server coolant type, solution peak concentration, solution heat exchanger effectiveness, evaporator temperature, and operating pressures on the performance of the novel system are investigated. Finally, using the thermodynamic model and cost information provided by the

  6. Efficiency analysis of alternative refrigerants for ejector cooling cycles

    Highlights: • Advantages of using alternative refrigerants as ejector refrigerants were presumed. • Computer software basing on theoretical model of Huang et al. (1999) was prepared. • Optimal temperature range of primary vapor for each working fluid was calculated. - Abstract: Computer software, basing on the theoretical model of Huang et al. with thermodynamic properties of selected refrigerants, was prepared. Investigation was focused on alternative refrigerants that belong to two groups of substances: common solvents (acetone, benzene, cyclopentane, cyclohexane and toluene) and non-flammable synthetic refrigerants applied in Organic Rankine Cycle (ORC) (R236ea, R236fa, R245ca, R245fa, R365mfc and RC318). Refrigerants were selected to detect a possibility to use them in ejector cooling system powered by a high-temperature heat source. A series of calculations were carried out for the generator temperature between 70 and 200 °C, with assumed temperatures of evaporation 10 °C and condensation 40 °C. Investigation revealed that there is no single refrigerant that ensures efficient operation of the system in the investigated temperature range of primary vapor. Each substance has its own maximum entrainment ratio and COP at its individual temperature of the optimum. The use of non-flammable synthetic refrigerants allows obtaining higher COP in the low primary vapor temperature range. R236fa was the most beneficial among the non-flammable synthetic refrigerants tested. The use of organic solvents can be justified only for high values of motive steam temperature. Among the solvents, the highest values of entrainment ratio and COP throughout the range of motive temperature were noted for cyclopentane. Toluene was found to be an unattractive refrigerant from the ejector cooling point of view

  7. Rotating Carnot-cycle magnetic refrigerators for use near 2 K

    The application or removal of a magnetic field of order 5 T to some Gd compounds at low temperatures results in 10-20 K adiabatic temperature changes or the isothermal expulsion or absorption of heat. In particular, the heat absorbed by 1 liter of appropriate magnetic material at 2 K is several hundred J. A rotating device is decribed which will allow cycle times of much less than 1 sec, resulting in approximately 1-kW refrigeration capacity for each liter of paramagnetic Gd compound. This heat could be expelled with better than 80% of Carnot efficiency into a helium refrigerator operating at 10-14 K

  8. ASHRAE`s new application guide for absorption cooling/refrigeration using recovered heat

    Dorgan, C.B.; Dorgan, C.E.; Leight, S.P. [Dorgan Associates, Inc., Madison, WI (United States)

    1995-12-31

    ASHRAE has a new publication, Application Guide for Absorption Cooling/Refrigeration Using Recovered Heat. This guide is a comprehensive reference manual for the application of indirect-fired absorption machines. An indirect-fired absorption machine uses heat recovered from another process or heat cycle machine versus a direct-fired absorption machine, which uses a primary fuel source. The Guide is designed to help engineers, owners, developers, and marketing personnel to become familiar with the requirements of an absorption system, evaluate indirect-fired absorption machines for specific requirements, evaluate the potential of available recovered heat sources, select the most economical system, and understand both lithium bromide (LiBr) and ammonia absorption machines. The Guide provides information on the application and economics of absorption machines. Detailed design of an absorption system is covered in other publications, which are listed in the Guide. The Guide introduces absorption technology through comparison with and using the terminology of vapor-compression technology. This information is then expanded to enable the reader to apply absorption technology to many situations where recovered heat is available.

  9. Waste Heat Powered Ammonia Absorption Refrigeration Unit for LPG Recovery

    Donald C, Energy Concepts Co.; Lauber, Eric, Western Refining Co.

    2008-06-20

    An emerging DOE-sponsored technology has been deployed. The technology recovers light ends from a catalytic reformer plant using waste heat powered ammonia absorption refrigeration. It is deployed at the 17,000 bpd Bloomfield, New Mexico refinery of Western Refining Company. The technology recovers approximately 50,000 barrels per year of liquefied petroleum gas that was formerly being flared. The elimination of the flare also reduces CO2 emissions by 17,000 tons per year, plus tons per year reductions in NOx, CO, and VOCs. The waste heat is supplied directly to the absorption unit from the Unifiner effluent. The added cooling of that stream relieves a bottleneck formerly present due to restricted availability of cooling water. The 350oF Unifiner effluent is cooled to 260oF. The catalytic reformer vent gas is directly chilled to minus 25oF, and the FCC column overhead reflux is chilled by 25oF glycol. Notwithstanding a substantial cost overrun and schedule slippage, this project can now be considered a success: it is both profitable and highly beneficial to the environment. The capabilities of directly-integrated waste-heat powered ammonia absorption refrigeration and their benefits to the refining industry have been demonstrated.

  10. Dynamic analysis of the CTAR (constant temperature adsorption refrigeration) cycle

    The basic SAR (solar-driven adsorption refrigeration) machine is an intermittent cold production system. Recently, the CO-SAR (continuous operation solar-powered adsorption refrigeration) system is developed. The CO-SAR machine is based on the theoretical CTAR (constant temperature adsorption refrigeration) cycle in which the adsorption process takes place at a constant temperature that equals the ambient temperature. Practically, there should be a temperature gradient between the adsorption bed and the surrounding atmosphere to provide a driving potential for heat transfer. In the present study, the dynamic analysis of the CTAR cycle is developed. This analysis provides a comparison between the theoretical and the dynamic operation of the CTAR cycle. The developed dynamic model is based on the D-A adsorption equilibrium equation and the energy and mass balances in the adsorption reactor. Results obtained from the present work demonstrate that, the idealization of the constant temperature adsorption process in the theoretical CTAR cycle is not far from the real situation and can be approached. Furthermore, enhancing the heat transfer between the adsorption bed and the ambient during the bed pre-cooling process helps accelerating the heat rejection process from the adsorption reactor and therefore approaching the isothermal process. - Highlights: • The dynamic analysis of the CTAR (constant temperature adsorption refrigeration) cycle is developed. • The CTAR theoretical and dynamic cycles are compared. • The dynamic cycle approaches the ideal one by enhancing the bed precooling

  11. Experimental Investigation on an Absorption Refrigerator Driven by Solar Cells

    Zi-Jie Chien; Hung-Pin Cho; Ching-Song Jwo; Chao-Chun Chien; Sih-Li Chen; Yen-Lin Chen

    2013-01-01

    This experiment is to study an absorption refrigerator driven by solar cells. Hand-held or carried in vehicle can be powered by solar energy in places without power. In the evenings or rainy days, it is powered by storage battery, and it can be directly powered by alternating current (AC) power supply if available, and the storage battery can be charged full as a backup supply. The proposed system was tested by the alternation of solar irradiance 550 to 700 W/m2 as solar energy and 500ml ambi...

  12. Simulator for design absorption refrigeration system; Simulador para projeto de ciclos de refrigeracao por absorcao

    Morejon, C.F.M.; Brum, N. de C. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Mecanica]. E-mails: Camilo_freddy@hotmail.com; Nisio@serv.com.ufrj.br

    2000-07-01

    This work presents a development of a thermal fluid dynamics model and a solution of a steady state absorption refrigeration cycle, with ammonia water as the working fluid. Analytical thermodynamics models expressing the enthalpy in function of pressure, temperature and composition (h=f(P,T,x)), are used with the aim to design all of the cycle devices, moved by any type of energy such as solar, natural gas, steam or electrical energy (Morejon and Hackenberg, 1978). The development of the analysis is carried out by the application of thermal fluid dynamics concepts together with a detailed study of the heat and mass transfer in the different cycle stages. The thermodynamic cycle model, obtained from equation of state for ammonia - water mixtures (Ziegker and Trepp, 1984), is represented by the relation h - x (enthalpy-composition) for different pressures and temperatures. The obtained models are used to implement computational codes in MAPLE-V facilitating the design and simulation of refrigeration system. This study can be applied in the systems of air conditioning and refrigeration chambers design. (author)

  13. A comparative study on the GAX based absorption refrigeration systems: SGAX, GAXH and GAX-E

    In this paper, two GAX-ejector absorption refrigeration cycles are proposed and investigated thermodynamically. In the first cycle (GAX-E Model A), the ejector draws vapor from the evaporator and raises the absorber pressure. In the second combined cycle (GAX-E Model B), the ejector is used to raise the condenser pressure. The performances of these two cycles are compared with those of the standard GAX (SGAX) cycle and two different arrangements of the hybrid GAX (GAXH Model A and GAXH Model B) cycles at the same working conditions. The comparison is performed through parametric studies in which the effects of generator and evaporator temperatures as well as the degassing range on the first and second law efficiencies are investigated. It is found that the COP of GAX-E Model B cycle is higher than that of the SGAX cycle by up to 16.7%. The maximum second law efficiency for the GAX-E Model B cycle is only slightly lower than the highest efficiency value which is obtained for the GAXH Model B cycle. As there is no compressor in the GAX-E Model B cycle, this cycle can be recommended for refrigeration purposes from the viewpoint of thermo-economics. - Highlights: ► Five different configurations of GAX based cycles are compared thermodynamically. ► For all the GAX cycles the highest exergy destructions occur in the absorber–desorber. ► The COP of standard GAX cycle is enhanced by 16.7% when an ejector is employed.

  14. Cooling, freezing and heating with the air cycle: air as the ultimate green refrigerant

    Verschoor, M.J.E.

    2000-01-01

    Due to the recent concern about the damage that CFCs cause to the environment (ozone layer, global warming) and the absence of commonly acceptable alternative refrigerants, the search for alternative refrigeration concepts is going on. Air as refrigerant in the Joule-Brayton cycle (air cycle) is one of the most natural refrigerants, and it meets all criteria for a refrigerant being environmentally benign. For this reason the air cycle is one of the most promising long-term alternatives for re...

  15. Development of Low Global Warming Potential Refrigerant Solutions for Commercial Refrigeration Systems using a Life Cycle Climate Performance Design Tool

    Abdelaziz, Omar; Fricke, Brian; Vineyard, Edward A.

    2012-01-01

    Commercial refrigeration systems are known to be prone to high leak rates and to consume large amounts of electricity. As such, both the direct emissions related to refrigerant leakage and the indirect emissions resulting from primary energy consumption contribute greatly to their Life Cycle Climate Performance (LCCP). In this paper, an LCCP design tool is used to evaluate the performance of a typical commercial refrigeration system with alternative refrigerants and minor system modifications...

  16. Thermodynamic analysis of an absorption refrigeration system with ionic-liquid/refrigerant mixture as a working fluid

    Thermodynamics of an ionic-liquid (IL) based absorption refrigeration system has been numerically analyzed. It provides an alternative to the normally toxic working fluids, such as the ammonia in conventional absorption systems. The use of ILs also eliminates crystallization and metal-compatibility problems of the water/LiBr system. Mixtures of refrigerants and imidazolium-based ILs are theoretically explored as the working fluid pairs in a miniature absorption refrigeration system, so as to utilize waste-heat to power a refrigeration/heat pump system for electronics cooling. A non-random two-liquid (NRTL) model was built and used to predict the solubility of the mixtures. Saturation temperatures at the evaporator and condenser were set at 25 °C and 50 °C, respectively, with the power dissipation of 100 W. Water in combination with [emim][BF4] (1-ethyl-3-methylimidazolium tetrafluoroborate) gave the highest coefficient of performance (COP) around 0.9. The refrigerant/IL compatibility indicated by the circulation ratio, alkyl chain length of the IL, and thermodynamic properties of the refrigerants, such as latent heat of evaporation were proven to be important factors in determining the performance of the absorption system. The negative effect of high viscosity was mitigated by dilution of the IL with the refrigerant and the use of slightly larger microfluidic channel heat exchangers. -- Highlights: ► Mixtures of refrigerant/ionic-liquid are studied for absorption system. ► We carry out comprehensive theoretical thermodynamic analysis. ► The essential factors of refrigerant/IL affecting the performance are identified. ► Water/[emim][BF4] showed the best performance of COP. ► The effects of high viscosity ILs on the system performance are not significant.

  17. PERFORMANCE OF A TWO-CYCLE REFRIGERATOR/FREEZER USING HFC REFRIGERANTS

    A two-cycle 18 ft3 (0.51 m3) refrigerator/freezer (R/F) was tested utilizing American National Standards Institute (ANSI)/AHAM (1988) standards for energy consumption testing. A 34.9% energy consumption reduction was realized. This work presents a proven method of reducing the ...

  18. Performance analysis and evaluation of a commercial absorption-refrigeration water-ammonia (ARWA) system

    Darwish, N.A.; Al-Hashimi, S.H.; Al-Mansoori, A.S. [The Chemical Engineering Program, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates)

    2008-11-15

    The Robur absorption-refrigeration water-ammonia (ARWA) system is analyzed using Aspen Plus flowsheet simulator. The results are compared with experimental and some manufacturer data reported in the open literature. Among performance parameters analyzed are coefficient of performance (COP), heat duties of the evaporator, absorber, and the condenser, refrigerant concentration in the weak and strong solution, and flow rates of the weak solution and the flow rate of refrigerant passing through the evaporator. In general, a very good agreement between the simulator's results and the experimental measurements was found. Also, results obtained for the effect of separator (input) heat duty on the COP agree well with the reported experimental data with a maximum percentage deviation of 1.8%. Efficiency of the separator in splitting off the refrigerant at the column top is shown to be of crucial importance; COP increased by 15% in going from 1 to 5 theoretical equivalent mass transfer stages in the separator. Some innovative modifications to Robur cycle aimed at enhancing the separator operation have shown a promising improvement in the COP. In particular, introducing a throttling process directly before the separator can alleviate the separator heat load and enhance the COP by up to 20%. Use of stripping gas injected at the bottom of the boiler is another strategy that has been investigated in this work. (author)

  19. Hourly performance prediction of ammonia–water solar absorption refrigeration

    This paper deals with the hourly performance investigation of solar absorption refrigeration (SAR) system with evacuated tube collector and ammonia–water (NH3–H2O) solution. The SAR system is presented to simulate the system characteristic variations using hourly atmospheric air temperature and solar radiation data for Adana province in Turkey. The evaluation is performed for the maximum temperature occurrence day on July 29. First, the variations of various parameters, such as absorption refrigeration machine efficiency, condenser capacity and heat transfer rate in the generator and absorber during the day, are calculated for different cooling capacities and generator temperatures. Later, the minimum evacuated tube collector surface area is determined. According to the obtained results, the SAR system is considerably suitable for home/office-cooling purposes between the hours 09:00 and 16:00 in the southern region of Turkey such as Adana province. The most suitable performance of the absorption cooling system is calculated for the generator temperature values equal to or higher than 110 °C. The performance coefficient of the cooling (COPcooling) varies in the range of 0.243–0.454 while that of the heating (COPheating) changes from 1.243 to 1.454 during the day. Evacuated tube collector area for a 3.5 kW cooling load capacity is found to be 35.95 m2 for the region at 16:00 whereas it is 19.85 m2 at 12:00. - Highlights: ► Hourly performance investigation of solar absorption NH3–H2O refrigeration system is performed. ► Hourly atmospheric temperature and solar radiation on July 29 for Adana province in Turkey were used in the analysis. ► Optimum generator temperature for evacuated tube collector type was determined as higher than 110 °C. ► COPcooling was calculated in the range of 0.243–0.454 between hours 09:00 and 16:00.

  20. General performance characteristics of an irreversible ferromagnetic Stirling refrigeration cycle

    G. Lin; E.H. Bruck; O. Tegus; L. Zhang

    2004-01-01

    A new magnetic-refrigeration-cycle model using ferromagnetic materials as a cyclic working substance is set up, in which finite-rate heat transfer, heat leak and regeneration time are taken into account. On the basis of the thermodynamic properties of a ferromagnetic material, the general performanc

  1. Thermal Losses Effect on the Performance of an Intermittent Solar Refrigeration Cycle for Generation Phase

    In this contribution, a study of the thermal losses effect undergone by the different parts of an intermittent absorption solar refrigeration cycle using the Ammonia/Water mixture is presented. After having shown the interest of the intermittent cycles through the discussion of the problem of the adaptation of these cycles to solar energy, mass and thermal assessments for each compartment of the installation were established for the two cases without and with thermal losses. The resulting differential equations system is solved numerically. The theoretical results obtained concern the temperature variations, the vapor flow as well as the compositions of the rich and the poor solutions

  2. Hierarchical Decomposition Thermodynamic Approach for the Study of Solar Absorption Refrigerator Performance

    Emma Berrich Betouche

    2016-03-01

    Full Text Available A thermodynamic approach based on the hierarchical decomposition which is usually used in mechanical structure engineering is proposed. The methodology is applied to an absorption refrigeration cycle. Thus, a thermodynamic analysis of the performances on solar absorption refrigerators is presented. Under the hypothesis of an endoreversible model, the effects of the generator, the solar concentrator and the solar converter temperatures, on the coefficient of performance (COP, are presented and discussed. In fact, the coefficient of performance variations, according to the ratio of the heat transfer areas of the high temperature part (the thermal engine 2 Ah and the heat transfer areas of the low temperature part (the thermal receptor Ar variations, are studied in this paper. For low values of the heat-transfer areas of the high temperature part and relatively important values of heat-transfer areas of the low temperature part as for example Ah equal to 30% of Ar, the coefficient of performance is relatively important (approximately equal to 65%. For an equal-area distribution corresponding to an area ratio Ah/Ar of 50%, the COP is approximately equal to 35%. The originality of this deduction is that it allows a conceptual study of the solar absorption cycle.

  3. Solar Absorption Refrigeration System for Air-Conditioning of a Classroom Building in Northern India

    Agrawal, Tanmay; Varun; Kumar, Anoop

    2015-10-01

    Air-conditioning is a basic tool to provide human thermal comfort in a building space. The primary aim of the present work is to design an air-conditioning system based on vapour absorption cycle that utilizes a renewable energy source for its operation. The building under consideration is a classroom of dimensions 18.5 m × 13 m × 4.5 m located in Hamirpur district of Himachal Pradesh in India. For this purpose, cooling load of the building was calculated first by using cooling load temperature difference method to estimate cooling capacity of the air-conditioning system. Coefficient of performance of the refrigeration system was computed for various values of strong and weak solution concentration. In this work, a solar collector is also designed to provide required amount of heat energy by the absorption system. This heat energy is taken from solar energy which makes this system eco-friendly and sustainable. A computer program was written in MATLAB to calculate the design parameters. Results were obtained for various values of solution concentrations throughout the year. Cost analysis has also been carried out to compare absorption refrigeration system with conventional vapour compression cycle based air-conditioners.

  4. Theoretical Study of New Combined Absorption-Ejector Refrigeration System

    Abed, A. M.; Sopian, K.; Alghoul, M. A.; Al-Shamani, A. N.; Ruslan, M. H.; Mat, S.

    2015-09-01

    An improved system of the new combined single stage absorption cycle operated with NH3/H2O as working fluid was performed. In order to enhance performance the cycle a new configuration of absorption system was utilized. The performances of two configurations of the combined absorption cycle were compared; a) with common solution heat exchanger and b) divided the streamline of solution heat exchanger to recover the internal heat. Based on the analysis, it has been shown that the second configuration a significant reduction of the required generator and absorber loads by about 20% and 17% respectively, with increased coefficient of performance (COP) about 12% compared to the first configuration. This improvement in the overall COP is found due to improve energy utilization efficiency significantly.

  5. Building and Experimentation of Diffusion Absorption Refrigeration Machines

    R. Mbarek

    2013-01-01

    Full Text Available This paper presents an experimental investigation of a drivenn-butane/octane (C4H10/ C8H18 diffusion absorption cooling machine according to the cycleof Platen and Munters. For that purpose, we construct a prototype designed for air-conditioning applications. The cooling capacity of the constructed machine is 55 W. A clear description of the constructed prototype is given. These researchers have a final goal which is coupling these types of cooling machines with solarenergy. In this paper, our major challenge is to design and choose the kind, the shape and dimensions of all components, which will afford a final and complete machine. In this experimental case, the value of COP reached was 0.3. Experimental results show that such refrigerator, simply fabricated, gives promising results and could be used for clean and safe use where there is agrowing interest.

  6. Performance analysis of solar powered absorption refrigeration system

    Abu-Ein, Suleiman Qaseem; Fayyad, Sayel M.; Momani, Waleed; Al-Bousoul, Mamdouh

    2009-12-01

    The present work provides a detailed thermodynamic analysis of a 10 kW solar absorption refrigeration system using ammonia-water mixtures as a working medium. This analysis includes both first law and second law of thermodynamics. The coefficient of performance (COP), exergetic coefficient of performance (ECOP) and the exergy losses (Δ E) through each component of the system at different operating conditions are obtained. The minimum and maximum values of COP and ECOP were found to be at 110 and 200°C generator temperatures respectively. About 40% of the system exergy losses were found to be in the generator. The maximum exergy losses in the absorber occur at generator temperature of 130°C for all evaporator temperatures. A computer simulation model is developed to carry out the calculations and to obtain the results of the present study.

  7. Parametric optimum design of an irreversible spin quantum refrigeration cycle

    Lin Bi-Hong; Chen Jin-Can

    2005-01-01

    The general performance characteristics of an irreversible quantum refrigeration cycle using many non-interacting spin-1/2 systems as the working substance and consisting of two adiabatic and two isomagnetic field processes are investigated, based on the quantum master equation and semi-group approach. Expressions for several important performance parameters such as the coefficient of performance, cooling rate and power input are derived. By using numerical solutions, the cooling rate of the refrigeration cycle subject to the finite cycle duration is optimized. The maximum cooling rate and the corresponding parameters are calculated numerically. The optimal region of the coefficient of performance and the optimal ranges of the temperatures of the working substance and the times spent on the two isomagnetic field processes are determined. Moreover, the optimal performance of the cycle in the high-temperature limit is also analysed in detail. The results obtained here are further generalized, so that they may be directly used to describe the performance of the quantum refrigeration cycle using spin-J systems as the working substance.

  8. Theoretical Study on CO2 Transcritical Cycle Combined Ejector Cycle Refrigeration System

    卢苇; 马一太; 李敏霞; 查世彤

    2003-01-01

    Chlorofluorocarbons(CFCs) or hydrochlorofluorocarbons(HCFCs) are as main refrigerants used in traditional refrigeration systems driven by electricity from burning fossil fuels, which is regarded as one of the major reasons for ozone depletion (man-made refrigerants emission) and global warming (CO2 emission). So people pay more and more attention to natural refrigerants and energy saving technologies. An innovative system combining CO2 transcritical cycle with ejector cycle is proposed in this paper. The CO2 compression sub-cycle is powered by electricity with the characteristics of relatively high temperature in the gas cooler (defined as an intercooler by the proposed system). In order to recover the waste heat, an ejector sub-cycle operating with the natural refrigerants (NH3, H2O) is employed. The two sub-cycles are connected by an intercooler. This combined cycle joins the advantages of the two cycles together and eliminates the disadvantages. The influences of the evaporation temperature in CO2 compression sub-cycle, the evaporation temperature in the ejector sub-cycle, the temperature in the intercooler and the condensation temperature in the proposed system performance are discussed theoretically in this study. In addition, some unique features of the system are presented.

  9. Experimental Comparison of the Refrigerant Reservoir Position in a Primary Loop Refrigerant Cycle with Optimal Operation

    Menken, Jan Christoph; Weustenfeld, Thomas; Köhler, Jürgen

    2014-01-01

    Recent attempts to find energy-efficient thermal management systems for electric and plug-in hybrid electric vehicles have led to secondary loop systems as an alternative approach to meet dynamic heating and cooling demands and reduce refrigerant charge. As such, a thorough understanding of the vapor compression cycle, which serves as the central thermal supply unit, is required. In addition to design considerations concerning the type and size of components such as the heat exchangers or com...

  10. New Regenerative Cycle for Vapor Compression Refrigeration

    Bergander, Mark J [Magnetic Development, Inc.; Butrymowicz, Dariusz [Polish Academy of Scinces

    2010-01-26

    This project was a continuation of Category 1 project, completed in August 2005. Following the successful bench model demonstration of the technical feasibility and economic viability, the main objective in this stage was to fabricate the prototype of the heat pump, working on the new thermodynamic cycle. This required further research to increase the system efficiency to the level consistent with theoretical analysis of the cycle. Another group of objectives was to provide the foundation for commercialization and included documentation of the manufacturing process, preparing the business plan, organizing sales network and raising the private capital necessary to acquire production facilities.

  11. Refrigeration cycle for cryogenic separation of hydrogen from coke oven gas

    Kun CHANG; Qing LI; Qiang LI

    2008-01-01

    Ten billion cubic meters of hydrogen are dissip-ated to the environment along with the emission of coke-oven gas every year in China. A novel cryogenic separation of hydrogen from coke oven gas is proposed to separate the hydrogen and liquefy it simultaneously, and the cooling capacity is supplied by two refrigeration cycles. The perform-ance of the ideal vapor refrigeration cycle is analyzed with methane and nitrogen as refrigerant respectively. The results show that the coefficient of performance (COP) of methane refrigeration cycle is 2.7 times that of nitrogen refrigeration cycle, and the figure of merit (FOM) of methane refrigera-tion cycle is 1.6 times that of nitrogen refrigeration cycle. The performance of ideal gas refrigeration cycle is also analyzed with neon, hydrogen and helium as refrigerant respectively. The results show that both the coefficient of performance and figure of merit of neon refrigeration cycle is the highest. It is thermodynamically possible to arrange the refrigeration cycle with methane and neon as refrigerant, respectively.

  12. Cooling, freezing and heating with the air cycle: air as the ultimate green refrigerant

    Verschoor, M.J.E.

    2000-01-01

    Due to the recent concern about the damage that CFCs cause to the environment (ozone layer, global warming) and the absence of commonly acceptable alternative refrigerants, the search for alternative refrigeration concepts is going on. Air as refrigerant in the Joule-Brayton cycle (air cycle) is one

  13. Gas Vapor Injection on Refrigerant Cycle Using Piston Technology

    Colmek, Sophie; Goderneaux, Laurent

    2012-01-01

    Gas vapor injection on refrigerant cycle is always used with Scroll, Rotary or others compressors technology to improve efficiency of the system at low and high ambient temperatures. Probably this kind of compressor is more adapted than the piston technology owing to their mechanical system. In this paper, we present the challenge of vapor injection realized on piston technology compressor range non for improving the cooling capacity of the system but to maintain the compressor temperature in...

  14. Experimental investigation of the ecological hybrid refrigeration cycle

    Cyklis Piotr; Kantor Ryszard; Ryncarz Tomasz; Górski Bogusław; Duda Roman

    2014-01-01

    The requirements for environmentally friendly refrigerants promote application of CO2 and water as working fluids. However there are two problems related to that, namely high temperature limit for CO2 in condenser due to the low critical temperature, and low temperature limit for water being the result of high triple point temperature. This can be avoided by application of the hybrid adsorption-compression system, where water is the working fluid in the adsorption high temperature cycle used ...

  15. AN EXPERIMENTAL STUDY ON A VAPOR COMPRESSION REFRIGERATION CYCLE BY ADDING INTERNAL HEAT EXCHANGER

    Muhammad Asmail Eleiwi

    2013-01-01

    Thispaper presents practical study to improve the indication COP of a vaporcompression refrigeration cycle in instrumented automobile air conditioner bydesigning internal heat exchanger and installing it in the vapor compressionrefrigeration cycle.  Two cases of  vapor compression refrigeration cycle were takenin this paper:  the first case is thatthe vapor compression refrigeration cycle without internal heat exchanger andin  the second case the vapor compressionrefrigeration cycle with heat...

  16. Computational tool for simulation of power and refrigeration cycles

    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.

  17. Magnetic vs. vapor-compression household refrigerators : A preliminary comparative life cycle assessment

    Monfared, Behzad; Furberg, Richard; Palm, Björn

    2014-01-01

    This paper seeks to shed light on the question whether a magnetic household refrigerator with permanent magnets is more environmentally friendly than a conventional, vapor-compression refrigerator. Life cycle assessment has been used as a tool to investigate the environmental impacts associated with the life cycle of a magnetic refrigerator. The results of the assessment have been compared with those of a conventional, vapor-compression refrigerator with the same functionality. The comparison...

  18. Performance of the Oxford miniature Stirling cycle refrigerator

    Bradshaw, T. W.; Delderfield, J.; Werrett, S. T.; Davey, G.

    The 'Oxford Cryocooler' miniature Stirling cycle cooler, a 5-kg mass split-cycle refrigerator developed for use aboard spacecraft, had as its design performance goal the production of 0.5 W of cooling power at 80 K for 30 W of electrical input power. The goal has actually been exceeded, prompting the present discussion of the compressor power budget and displacer losses. Attention is given to graphs of the cold-end temperature vs. compressor input power and cooling power. The cooler is to be used on the Improved Stratospheric and Mesospheric Sounder experiment of the Upper Atmosphere Research Satellite.

  19. ASHRAE`s new application guide for absorption cooling/refrigeration using recovered heat

    Dorgan, C.B.; Dorgan, C.E.; Leight, S.P. [Dorgan Associates Inc., Madison, WI (United States)

    1995-07-01

    This article is a brief overview of the Guide for Absorption Cooling/Refrigeration Using Recovered Heat. The overview examines the applications of the guide, it`s format and topics on a chapter basis. The authors report that ASHRAE`s purpose for developing this manual is to encourage more engineers and owners to consider using recovered heat for cooling and refrigeration.

  20. Study of optimal discharge pressure of compressor in CO_2 refrigerating trans-critical cycle

    2008-01-01

    In this paper, a carbon dioxide trans-critical refrigerating system which is different from a conventional subcritical refrigerating cycle was studied. The trans-critical carbon dioxide refrigerating systems are based on the Gustav Lorntzen cycle. Emphasis was focused on how to determine the optimal discharge pressure of compressor in CO2 trans-critical cycle. The factors related with the optimal discharge pressure were analyzed. A formula was developed based on cycle simulation, which could be used to pred...

  1. Control structure selection for vapor compression refrigeration cycle

    Yin, Xiaohong; Li, Shaoyuan [Shanghai Jiao Tong Univ., Shanghai (China). Dept. of Automation; Shandong Jianzhu Univ., Jinan (China). School of Information and Electrical Engineering; Cai, Wenjian; Ding, Xudong [Nanyang Technological Univ., Singapore (Singapore). School of Electrical and Electronic Engineering

    2013-07-01

    A control structure selection criterion which can be used to evaluate the control performance of different control structures for the vapor compression refrigeration cycle is proposed in this paper. The calculation results of the proposed criterion based on the different reduction models are utilized to determine the optimized control model structure. The effectiveness of the criterion is verified by the control effects of the model predictive control (MPC) controllers which are designed based on different model structures. The response of the different controllers applied on the actual vapor compression refrigeration system indicate that the best model structure is in consistent with the one obtained by the proposed structure selection criterion which is a trade-off between computation complexity and control performance.

  2. Combined Refrigeration Cycle for Thermal Power Plant Using Low Grade Waste Steam

    Satish Maurya*,

    2014-02-01

    Full Text Available Now a days, In most of the thermal power plant, where low-pressure steam is being exhausted to the atmosphere as a waste steam. This waste heat could be use to operate many small preheating or cooling equipments or small scale plants. There are many refrigeration systems present for refrigeration and air condition purpose. Such as air refrigeration, vapour compression, vapour absorption etc. In this paper we have presented the concept of combined vapour absorption and vapour compression refrigeration system. We present about the idea discuss here that how a vapour absorption and vapour compression can be used together as one complete working refrigeration plant. By using such concept of refrigeration we can improve the co-efficient of performance of whole plant by minimizing the input. We can also named the system as waste heat recovery refrigeration system.

  3. Conceptual design of nuclear CHP using absorption cycle

    This paper aims at providing a conceptual idea on the combined heat and power (CHP) using the absorption cycle to simultaneously generate both electricity and useful heat, which is applicable to the conventional nuclear power plants (NPPs). The originality of the scheme is 1) it does not change the operation strategy of the NSSS, 2) the thermal energy of waste heat can be transferred to a long distance, and 3) the thermal energy can be used for cooling as well. As it is expected that the number and the share of NPPs increases soon, the necessity of a partial load operation was raised in argument in case of South Korea. This means the surplus of nuclear energy. In order to make the best of nuclear fuels loaded once, we proposed a combined cycle instead of cutting back reactor power to meet a partial load demand. Figure 1 shows the schematic drawing of the proposal. Since a steam demand in the turbine cycle is equivalent even though an electricity demand is different, the operation strategy of the NSSS does not need to be changed. When a partial load demand is triggered off, turbine power is cut back and a bypass path is open. The bypass path is used for transferring waste heat to an absorption cycle. The CHP using absorption principles was initially developed over 100 years ago. The absorption cycle is a process by which heating and/or cooling effect is produced through the use of two fluids and some quantity of heat input. The absorption cycles accomplish heat transferring through the evaporation of a refrigerant at a low pressure and the rejection of heat through the condensation of the refrigerant at a higher pressure. In the absorption cycles, a secondary fluid or absorbent is used to circulate the refrigerant. Absorption cycles are commercially available today in two basic configurations; lithium bromide/water and water/ammonia (respectively absorbent/ refrigerant). We can have several advantages in this idea. This principle can design a heat transfer mechanism

  4. Stirling-cycle rotating magnetic refrigerators and heat engines for use near room temperature

    The application (or removal) of a magnetic field to the ferromagnetic Gd metal near its Curie point (293 K) will produce adiabatic heating (or cooling) of 14 K or isothermal expulsion (or absorption) of 32 kJ of heat per liter of Gd metal. A refrigerator and a heat engine are described for which porous Gd metal forms the rim of a wheel rotating into and out of a magnetic field region. Fluid forced to flow through the porous metal exchanges heat; the field and flow configurations are such that the metal executes a magnetic Stirling cycle allowing a very wide temperature span (many times 14 K) while maintaining the 32-kJ/l capacity. Efficiencies approaching that of Carnot are expected at 1-Hz rotation rates, resulting in 32-kW/l refrigeration or heating capacity

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

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

  6. Combined Refrigeration Cycle for Thermal Power Plant Using Low Grade Waste Steam

    Satish Maurya*,; Dharmendra Patel

    2014-01-01

    Now a days, In most of the thermal power plant, where low-pressure steam is being exhausted to the atmosphere as a waste steam. This waste heat could be use to operate many small preheating or cooling equipments or small scale plants. There are many refrigeration systems present for refrigeration and air condition purpose. Such as air refrigeration, vapour compression, vapour absorption etc. In this paper we have presented the concept of combined vapour absorption and vapour compression refri...

  7. THERMODYNAMIC EVALUATION OF FIVE ALTERNATIVE REFRIGERANTS IN VAPOR-COMPRESSION CYCLES

    The paper gives results of a thermodynamic evaluation of five alternative refrigerants in a vapor-compression refrigeration cycle, utilizing throttling, super-heating, and combined throttling and superheating. ive alternative refrigerants (R32, R125, R134a, R143a, and R152a) were...

  8. Experimental investigation of the ecological hybrid refrigeration cycle

    Cyklis, Piotr; Kantor, Ryszard; Ryncarz, Tomasz; Górski, Bogusław; Duda, Roman

    2014-09-01

    The requirements for environmentally friendly refrigerants promote application of CO2 and water as working fluids. However there are two problems related to that, namely high temperature limit for CO2 in condenser due to the low critical temperature, and low temperature limit for water being the result of high triple point temperature. This can be avoided by application of the hybrid adsorption-compression system, where water is the working fluid in the adsorption high temperature cycle used to cool down the CO2 compression cycle condenser. The adsorption process is powered with a low temperature renewable heat source as solar collectors or other waste heat source. The refrigeration system integrating adsorption and compression system has been designed and constructed in the Laboratory of Thermodynamics and Thermal Machine Measurements of Cracow University of Technology. The heat source for adsorption system consists of 16 tube tulbular collectors. The CO2 compression low temperature cycle is based on two parallel compressors with frequency inverter. Energy efficiency and TEWI of this hybrid system is quite promising in comparison with the compression only systems.

  9. Experimental investigation of the ecological hybrid refrigeration cycle

    Cyklis Piotr

    2014-09-01

    Full Text Available The requirements for environmentally friendly refrigerants promote application of CO2 and water as working fluids. However there are two problems related to that, namely high temperature limit for CO2 in condenser due to the low critical temperature, and low temperature limit for water being the result of high triple point temperature. This can be avoided by application of the hybrid adsorption-compression system, where water is the working fluid in the adsorption high temperature cycle used to cool down the CO2 compression cycle condenser. The adsorption process is powered with a low temperature renewable heat source as solar collectors or other waste heat source. The refrigeration system integrating adsorption and compression system has been designed and constructed in the Laboratory of Thermodynamics and Thermal Machine Measurements of Cracow University of Technology. The heat source for adsorption system consists of 16 tube tulbular collectors. The CO2 compression low temperature cycle is based on two parallel compressors with frequency inverter. Energy efficiency and TEWI of this hybrid system is quite promising in comparison with the compression only systems.

  10. Frequency Response Adaptive Control of a Refrigeration Cycle

    Jens G. Balchen

    1989-01-01

    Full Text Available A technique for the adaptation of controller parameters in a single control loop based upon the estimation of frequency response parameters has been presented in an earlier paper. This paper contains an extension and a generalization of the first method and results in a more versatile solution which is applicable to a wider range of process characteristics. The application of this adaptive control technique is illustrated by a laboratory refrigeration cycle in which the evaporator pressure controls the speed of the compressor.

  11. Thermodynamic analysis of a combined reheat regenerative thermal power plant and water–LiBr vapor absorption refrigeration system

    Highlights: • Thermodynamic analysis of a combined power-absorption cooling system is provided. • Effect of important operating parameters on combined cycle performance is studied. • Compares performance of combined cycle with power cycle without absorption system. • Gives quantitative comparison of power cycle performance with and without water heater. • Analysis on vapor power and water–LiBr absorption refrigeration system is not available. - Abstract: Detail thermodynamic analysis of a combined reheat regenerative steam turbine (ST) based power cycle and water–LiBr vapor absorption refrigeration system (VARS) is presented in this study. The power cycle uses one open and one closed water heater (CWH) for purpose of feed water heating. A parametric analysis is performed to investigate the effects of boiler pressure, fuel flow rate, VARS evaporator cooling load and operating temperatures on performance of the topping power cycle and bottoming VARS. Further a performance comparison of the combined power and cooling plant is made with the power plant (without VARS) to quantify the performance variation due to VARS integration. Comparative performance analysis is also provided for the power plant (without VARS) with and without the CWH in the plant. The analysis indicates that the fuel flow rate and boiler pressure affects only the power cycle performance while the evaporator cooling load and VARS components’ operating temperature has its combined effect both on the power and the cooling system, the evaporator cooling load is the most crucial among them. A sensitive analysis shows that the power and efficiency of the topping cycle change very little with VARS operating temperatures. VARS coefficient of performance is more sensitive to the change in condenser and absorber temperature compared to change in generator and evaporator temperature

  12. Thermodynamic performance of an auto-cascade ejector refrigeration cycle with mixed refrigerant R32 + R236fa

    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

  13. Synthesis of integrated absorption refrigeration systems involving economic and environmental objectives and quantifying social benefits

    This paper presents a new methodology for energy integration of systems that require absorption refrigeration. It allows heat exchange among process hot and cold streams and the integration of excess process heat as well as external utilities provided by solar energy, fossil fuels and biofuels. An optimization formulation is developed to address the multiple objectives of simultaneously minimizing the total annualized cost and the greenhouse gas emissions while the social impact is measured by the number of jobs generated by the project in the entire life cycle. The economic function accounts for the tax credit obtained by the reduction of greenhouse gas emissions when cleaner technologies are used. The proposed model also considers the optimal selection of different types of solar collectors and the optimal time-based usage of solar energy, fossil fuel, and biofuel. Two example problems are presented to show the applicability of the proposed methodology. -- Highlights: ► An approach for the thermal integration of refrigeration processes is proposed. ► Different forms of sustainable energies are considered in the optimization process. ► Economic and environmental objectives are considered quantifying the number of jobs. ► The availability for the different forms of energy is taken into account. ► Results show significant advantages obtained with the proposed approach

  14. A new technology for fishing vessels: the use of ejector expansion refrigeration cycle

    Memet, Feiza; Mitu, Daniela Elena

    2015-02-01

    A challenge that fishing industry is facing is the improvement of the refrigeration technology on board of fishing vessels. This paper deals with vapor compression refrigeration systems included on board of these ships. In these systems, significant thermodynamic losses are encountered in the expansion valve, during throttling process. Because it is possible to improve a thermodynamic process by decreasing irreversibility, in this paper it is used an ejector in order to reduce throttling irreversibility. A new technology results, the use of an ejector as a refrigerant expander leading to the ejector expansion refrigeration cycle. The theoretical study developed here will reveal a performance improvement of the new cycle. Also, because the traditional refrigerant used in marine refrigeration is R 134a, which presents a high value of its Global Warming Potential, the performance analysis is extended for the case of the use of other more environmentally friendly refrigerants: propane and isobutane.

  15. Materials and systems developments on solid absorption refrigeration with CaCl2·xNH3

    The paper presents some developments on the stabilization of CaCl2 for use as a solid absorption material in refrigerators, the development of a refrigerator using the stabilized salt, and computer modelling of the refrigerator system. (author). 8 refs, 19 figs

  16. Parametric analysis of an irreversible proton exchange membrane fuel cell/absorption refrigerator hybrid system

    A hybrid system mainly consisting of a PEMFC (proton exchange membrane fuel cell) and an absorption refrigerator is proposed, where the PEMFC directly converts the chemical energy contained in the hydrogen into electrical and thermal energies, and the thermal energy is transferred to drive the bottoming absorption refrigerator for cooling purpose. By considering the existing irreversible losses in the hybrid system, the operating current density region of the PEMFC permits the absorption refrigerator to exert its function is determined and the analytical expressions for the equivalent power output and efficiency of the hybrid system under different operating conditions are specified. Numerical calculations show that the equivalent maximum power density and the corresponding efficiency of the hybrid system can be respectively increased by 5.3% and 6.8% compared to that of the stand-alone PEMFC. Comprehensive parametric analyses are conducted to reveal the effects of the internal irreversibility of the absorption refrigerator, operating current density, operating temperature and operating pressure of the PEMFC, and some integrated parameters related to the thermodynamic losses on the performance of the hybrid system. The model presented in the paper is more general than previous study, and the results for some special cases can be directly derived from this paper. - Highlights: • A CHP system composed of a PEMFC and an absorption refrigerator is proposed. • Current density region enables the absorption refrigerator to work is determined. • Multiple irreversible losses in the system are analytically characterized. • Maximum power density and corresponding efficiency can be increased by 5.3% and 6.8%. • Effects of some designing and operating parameters on the performance are discussed

  17. Thermodynamic Analysis and Comparison on Low Temperature CO2-NH3 Cascade Refrigeration Cycle

    查世彤; 马一太; 申江; 李敏霞

    2003-01-01

    This paper is focused on the cascade refrigeration cycle using natural refrigerant CO2-NH3. The properties of refrigerants CO2 and NH3 are introduced and analyzed.CO2 has the advantage in low stage of cascade refrigeration cycle due to its good characteristics and properties. The thermodynamic analysis results of the CO2-NH3 cascade refrigeration cycle demonstrates that the cycle has an optimum condensation temperature of low stage and also has an optimum flow rate ratio.By comparing with the R13-R22 and NH3-NH3 cascade refrigeration cycles, the mass flow rate ratio of CO2-NH3 is larger than those of R13-R22 and NH3-NH3, the theoretical COP of CO2-NH3 cascade refrigeration cycle is larger than that of the R13-R22 cascade cycle and smaller than that of the NH3-NH3 cascade cycle. But the real COP of CO2-NH3 cascade cycle will be higher than those of R13-R22 and NH3-NH3 because the specific volume of CO2 at low temperature does not change much and its dynamic viscosity is also small.

  18. AN EXPERIMENTAL STUDY ON A VAPOR COMPRESSION REFRIGERATION CYCLE BY ADDING INTERNAL HEAT EXCHANGER

    Muhammad Asmail Eleiwi

    2013-05-01

    Full Text Available Thispaper presents practical study to improve the indication COP of a vaporcompression refrigeration cycle in instrumented automobile air conditioner bydesigning internal heat exchanger and installing it in the vapor compressionrefrigeration cycle.  Two cases of  vapor compression refrigeration cycle were takenin this paper:  the first case is thatthe vapor compression refrigeration cycle without internal heat exchanger andin  the second case the vapor compressionrefrigeration cycle with heat exchanger ; in these two cases, the temperatureat each point of  a vapor compressionrefrigeration cycle, the low and the high pressure ,the indoor temperature andthe outdoor temperature were measured at each time at compressor speed 1450 rpmand 2900 rpm for each blower speed 1, blower speed 2 and blower speed 3.Therefrigerant fluid was used in the vapor compression refrigeration cycle withoutIHE and with IHE is R134a..

  19. Refrigerator with variable capacity compressor and cycle priming action through capacity control and associated methods

    Gomes, Alberto Regio; Litch, Andrew D.; Wu, Guolian

    2016-03-15

    A refrigerator appliance (and associated method) that includes a condenser, evaporator and a multi-capacity compressor. The appliance also includes a pressure reducing device arranged within an evaporator-condenser refrigerant circuit, and a valve system for directing or restricting refrigerant flow through the device. The appliance further includes a controller for operating the compressor upon the initiation of a compressor ON-cycle at a priming capacity above a nominal capacity for a predetermined or calculated duration.

  20. A thermodynamic review of cryogenic refrigeration cycles for liquefaction of natural gas

    Chang, Ho-Myung

    2015-12-01

    A thermodynamic review is presented on cryogenic refrigeration cycles for the liquefaction process of natural gas. The main purpose of this review is to examine the thermodynamic structure of various cycles and provide a theoretical basis for selecting a cycle in accordance with different needs and design criteria. Based on existing or proposed liquefaction processes, sixteen ideal cycles are selected and the optimal conditions to achieve their best thermodynamic performance are investigated. The selected cycles include standard and modified versions of Joule-Thomson (JT) cycle, Brayton cycle, and their combined cycle with pure refrigerants (PR) or mixed refrigerants (MR). Full details of the cycles are presented and discussed in terms of FOM (figure of merit) and thermodynamic irreversibility. In addition, a new method of nomenclature is proposed to clearly identify the structure of cycles by abbreviation.

  1. The Use of Water Vapor as a Refrigerant: Impact of Cycle Modifications on Commercial Viability

    Brandon F. Lachner, Jr.; Gregory F. Nellis; Douglas T. Reindl

    2004-08-30

    This project investigated the economic viability of using water as the refrigerant in a 1000-ton chiller application. The most attractive water cycle configuration was found to be a flash-intercooled, two-stage cycle using centrifugal compressors and direct contact heat exchangers. Component level models were developed that could be used to predict the size and performance of the compressors and heat exchangers in this cycle as well as in a baseline, R-134a refrigeration cycle consistent with chillers in use today. A survey of several chiller manufacturers provided information that was used to validate and refine these component models. The component models were integrated into cycle models that were subsequently used to investigate the life-cycle costs of both an R-134a and water refrigeration cycle. It was found that the first cost associated with the water as a refrigerant cycle greatly exceeded the savings in operating costs associated with its somewhat higher COP. Therefore, the water refrigeration cycle is not an economically attractive option to today's R-134a refrigeration system. There are a number of other issues, most notably the requirements associated with purging non-condensable gases that accumulate in a direct contact heat exchanger, which will further reduce the economic viability of the water cycle.

  2. Thermodynamic analysis of transcritical CO2 refrigeration cycle with an ejector

    A comparative study on transcritical carbon dioxide refrigeration cycle with ejector and with throttling valve was performed by the first and second laws of thermodynamics in theory. The effects of the entrainment ratio of the ejector, heat rejection pressure, outlet temperature of gas cooler and evaporating temperature on the coefficient of performance (COP) and exergy loss were investigated in transcritical carbon dioxide refrigeration cycle with ejector and with throttling valve. It is found that ejector instead of throttling valve can reduce more 25% exergy loss and increase COP more 30%. In addition, critical entrainment ratio of the ejector, optimal heat rejection pressure and critical outlet temperature of gas cooler affects COP greatly for the transcritical carbon dioxide refrigerating cycle with ejector. - Research highlights: →Transcritical CO2 refrigeration cycle with ejector was analyzed by the laws of thermodynamics. → The ejector instead of throttling valve reduces more 25% exergy loss and increases COP more 30% in transcritical CO2 refrigeration cycle. → COP of transcritical CO2 refrigeration cycle with ejector was affected greatly by entrainment ratio of ejector, rejection pressure and outlet temperature of gas cooler. → Running condition of transcritical CO2 refrigeration cycle with ejector is limited by critical entrainment ratio of the ejector.

  3. Improvement in performance of a direct solar-thermally driven diffusion-absorption refrigerator; Leistungssteigerung einer direkt solarthermisch angetriebenen Diffusions-Absorptionskaeltemaschine

    Schmid, Fabian; Bierling, Bernd; Spindler, Klaus [Stuttgart Univ. (Germany). Inst. fuer Thermodynamik und Waermetechnik (ITW)

    2012-07-01

    The diffusion-absorption refrigeration process offers the possibility of a wear-free refrigeration system without electricity and noise. At the Institute for Thermodynamics and Thermal Engineering (Stuttgart, Federal Republic of Germany), a decentralized solar refrigeration system is developed based on this process. The expeller and the thermosiphon pump of this process are integrated in the collector, and thus are heated directly. The diffusion-absorption refrigeration process also can be used for domestic water heating by means of a second cycle in the collector. A cooling capacity of 400 W is to be achieved for each solar collector (2.5 m{sup 2}). Several refrigeration systems can be modular interconnected for higher cooling capacities. As part of the DKV Conference 2011, the construction of the plant, the first measurement data and results were presented. Since then, both the cooling capacity and the coefficient of performance of the diffusion-absorption refrigeration system could be increased significantly. For this, solvent heat exchanger, evaporator, absorber and gas heat exchanger have been optimized in terms of system efficiency. In addition, a stable system operation could be achieved by means of a bypass line. About this line, an exaggerated refrigerant already is removed in the solvent heat exchanger. In addition, a condensate pre-cooler was integrated in order to increase the efficiency. For a detailed investigation of the auxiliary gas cycle facilities, the volume flow and the concentration of the auxiliary gas circuit were examined under utilization of an ultrasonic sensor. In order to evaluate the influence factors by means of a parametric study, the mass transfer in the auxiliary gas circuit was simulated using the two-fluid model. The results of these studies, the current system configuration and the current results are presented in the contribution under consideration.

  4. Application of waste heat powered absorption refrigeration system to the LNG recovery process

    Kalinowski, Paul; Hwang, Yunho; Radermacher, Reinhard [Center for Environmental Energy Engineering, Department of Mechanical Engineering, University of Maryland, College Park, MD 20742 (United States); Al Hashimi, Saleh; Rodgers, Peter [The Petroleum Institute, Abu Dhabi (United Arab Emirates)

    2009-06-15

    The recovery process of the liquefied natural gas requires low temperature cooling, which is typically provided by the vapor compression refrigeration systems. The usage of an absorption refrigeration system powered by waste heat from the electric power generating gas turbine could provide the necessary cooling at reduced overall energy consumption. In this study, a potential replacement of propane chillers with absorption refrigeration systems was theoretically analyzed. From the analysis, it was found that recovering waste heat from a 9 megawatts (MW) electricity generation process could provide 5.2 MW waste heat produced additional cooling to the LNG plant and save 1.9 MW of electricity consumption. Application of the integrated cooling, heating, and power is an excellent energy saving option for the oil and gas industry. (author)

  5. FUZZY THERMOECONOMIC APPROACH TO NANOFLUID SELECTION IN VAPOR COMPRESSION REFRIGERATION CYCLE

    D. Kuleshov

    2014-06-01

    Full Text Available The working fluid selection in the vapour compression refrigeration cycles has been studied as a fuzzy thermoeconomic optimization problem. Three criteria: thermodynamic (COP Coefficient Of Performance, economic (LCC Life Cycle Cost, and ecologic (GWP – Global Warming Potential are chosen as target functions. The decision variables X as an information characteristics of desired refrigerant are presented by its critical parameters and normal boiling temperature. Local criteria are expressed via thermodynamic properties restored from information characteristics of refrigerant X, as well as life cycle costs are calculated by the standard economic relationships. GWP values are taken from the refrigerant database. Class of substances under consideration is presented by the natural refrigerant R600a embedded with nanostructured materials.

  6. The Effects of Internal and External Irreversibility of a Vapor Compression Refrigeration Cycle

    Wang, Fu-Jen; Chiou, Jeng-Shing

    The concept of finite-time thermodynamics is employed to investigate the optimal refrigeration rate for an irreversible refrigeration cycle. The heat transfer between the system (internal) fluid and cooling (external) fluid takes place at the actual heat exchanger, which has the finite-size heat transfer area and the realistic heat transfer effectiveness. The internal irreversibility results from the compression process and the expansion process are also considered. The optimal refrigeration rate is calculated and expressed in terms of the irreversibility parameter (Ir), coefficient of performance (COP), the time ratio(γ) of heat transfer processes and the effectiveness of heat exchanger. The derived COP which consider both the external and internal irreversibility can thus be considered as the benchmark value for a practical refrigeration cycle, and the parametric study can provide the basis for both determination of optimal operating conditions and design of a practical refrigeration cycle.

  7. Geothermal absorption refrigeration for food processing industries. Final report, December 13, 1976--November 13, 1977

    Harris, R.L.; Olson, G.K.; Mah, C.S.; Bujalski, J.H.

    1977-11-01

    The first step in the economic analysis of the integration of geothermally powered absorption refrigeration into a food processing plant was an evaluation of the potential geothermal sites in the Western United States. The evaluation covered availability of raw materials, transportation, adequate geothermal source, labor, and other requirements for food processing plants. Several attractive geothermal sites were identified--Raft River, Idaho; Sespe Hot Springs, California; Vale Hot Springs, Oregon; Weisler-Crane Creek, Idaho; Cosco Hot Springs, California; and the Imperial Valley, California. The most economically attractive food processing industry was then matched to the site based on its particular energy, raw material, and transportation requirements. The more promising food processors identified were for frozen potato or vegetable products, freeze-dried products, and meat processing. For the refrigeration temperature range of +32/sup 0/F to -40/sup 0/F and geothermal temperature range of 212/sup 0/F to 300/sup 0/F, an absorption refrigeration system had to be identified, designed, and evaluated. Both the conventional ammonia/water and an organic absorption refrigeration system using monochlorodifluoromethane (R-22) as the refrigerant and dimethyl formamide (DMF) as the absorbent were studied. In general, only a 60/sup 0/F to 100/sup 0/F temperature drop would be effectively used for refrigeration leaving the remainder of the allowable temperature drop available for other use. The economic evaluation of the geothermal system installed in a food processing plant required the comparison of several principal alternatives. These alternatives were evaluated for three different food processing plants located at their optimum geothermal site: a forzen potato product processing plant located at Raft River, Idaho; a freeze-dried product plant located at Sespe Hot Springs, California; a beef slaughter operation located in the Imperial Valley of California. (JGB)

  8. Performance evaluation of an ejector subcooled vapor-compression refrigeration cycle

    Highlights: • An ejector subcooled vapor-compression refrigeration cycle is proposed. • The performance of the cycle with ejector subcooling is evaluated theoretically. • Increase in refrigeration capacity can be achieved by the ejector subcooled cycle. • The new cycle exhibits higher COP compared to the basic single-stage cycle. • Performance of the new cycle depends on the operation pressures of the ejector. - Abstract: In this study, a novel vapor-compression refrigeration cycle with mechanical subcooling using an ejector is proposed to improve the performance of a conventional single-stage vapor-compression refrigeration cycle. In the theoretical study, a mathematical model is developed to predict the performance of the cycle by using R404A and R290, and then compared with that of the conventional refrigeration cycle. The simulation results show that the performance of the ejector subcooled cycle is better than that of the conventional cycle. When the evaporator temperature ranges from −40 to −10 °C and the condenser temperature is 45 °C, the novel cycle displays volumetric refrigeration capacity improvements of 11.7% with R404A and 7.2% with R290. And the novel cycle achieves COP improvements of 9.5% with R404A and 7.0% with R290. In addition, the improvement of the COP and cooling capacity of this novel cycle largely depends on the operation pressures of the ejector. The potential practical advantages offered by the cycle may be worth further attention in future studies

  9. COP Prediction of an ejector refrigeration cycle combined with a vapour compression cycle for automotive air conditioning

    Nat Suvarnakuta; Nutthanun Keerlatiyadatanapat; Thanarath Sriveerakul

    2014-01-01

    This paper presents the COP prediction of an ejector refrigeration cycle combined with a vapour compression cycle for automotive air conditioning. Using computational fluid dynamics (CFD) technique, the performance of an ejector was analyzed in term of the entrainment ratio (Rm) and critical back pressure (CBP). The results from this study were compared with a previous study of combined ejector refrigeration system for automotive air conditioning application [1] which the entrainment ratio (R...

  10. Evaluation of a system of refrigeration with absorption cycle using the direct burning of natural gas for tropical fruits storage; Avaliacao de um sistema de refrigeracao com ciclo de absorcao utilizando a queima direta de gas natural para armazenamento de frutas tropicais

    Bartolomeu, Lair S.; Torres, Ednildo A. [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Escola Politecnica. Lab. de Energia e Gas; Silva, Gabriel F. [Universidade Federal de Sergipe (UFS), Aracaju, SE (Brazil); Martins, Ronaldo M. [PETROBRAS, Rio de Janeiro, RJ (Brazil). Materiais. CQDM; Campos, Michel F. [PETROBRAS, Rio de Janeiro, RJ (Brazil). Gerencia de Tecnologia do Gas Natural. Rede GasEnergia

    2004-07-01

    This work has the purpose to analyze an alternative method in the conservation of tropical fruits in chamber cooled through the technology of use of the natural gas as energy source. The study it was carried through in chiller of absorption, Robur model, of 5TR, which meets in the campus of the Federal University of Sergipe (UFS/LEG). The energy analysis had as objective to study the process involving the cycle and its components. Of the analysis of first law was gotten a power of refrigeration of 8,8 kW and a COP=0,32 and the analysis of second law {beta}=0,29. The exergetic analysis had for intention to evaluate the amount and the quality of the energy in the system. The heat generator was the component that presented the biggest irreversibility, whose relation with the total irreversibility was about 70%. In the absorber the lesser exergetic efficiency was verified. Project is supported by the GasEnergia/PETROBRAS. (author)

  11. Study of optimal discharge pressure of compressor in CO2 refrigerating trans-critical cycle

    Fu Liehu; Wang Ruixiang; Li Qingdong; Wu Yezheng

    2008-01-01

    In this paper, a carbon dioxide trans-critical refrigerating system which is different from a conventional subcritical refrigerating cycle was studied. The trans-critical carbon dioxide refrigerating systems are based on the Gustav Lorntzen cycle. Emphasis was focused on how to determine the optimal discharge pressure of compressor in CO2 trans-critical cycle. The factors related with the optimal discharge pressure were analyzed. A formula was developed based on cycle simulation, which could be used to predict the optimal discharge pressure of a basic CO2 trans-critical cycle. After further studies on CO2 trans-critical cycles with a regenerator or expander, two more formulas were also developed. These formulas could provide an access to improve the COP of CO2 trans-critical cycle.

  12. Neon turbo-Brayton cycle refrigerator for HTS power machines

    Hirai, Hirokazu; Hirokawa, M.; Yoshida, Shigeru; Nara, N.; Ozaki, S.; Hayashi, H.; Okamoto, H.; Shiohara, Y.

    2012-06-01

    We developed a prototype turbo-Brayton refrigerator whose working fluid is neon gas. The refrigerator is designed for a HTS (High Temperature Superconducting) power transformer and its cooling power is more than 2 kW at 65 K. The refrigerator has a turboexpander and a turbo-compressor, which utilize magnetic bearings. These rotational machines have no rubbing parts and no oil-components. Those make a long maintenance interval of the refrigerator. The refrigerator is very compact because our newly developed turbo-compressor is volumetrically smaller than a displacement type compressor in same operating specification. Another feature of the refrigerator is a wide range operation capability for various heat-loads. Cooling power is controlled by the input-power of the turbo-compressor instead of the conventional method of using an electric heater. The rotational speed of the compressor motor is adjusted by an inverter. This system is expected to be more efficient. We show design details, specification and cooling test results of the new refrigerator in this paper.

  13. Thermodynamic Investigation of Two-Stage Absorption Refrigeration System Connected by a Compressor

    L. Kairouani

    2005-01-01

    Full Text Available The present work is to analyze a two-stage cycle based on the ammonia-water absorption system, with intermediate compression. The two generators of the system are heated by geothermal energy at low temperature. The study shows that this system makes it possible at lower generator temperature, under the limits permitted by the systems suggested up to now. For Tg = 335 K, Tc = Ta = 308 K and Te = 263 K, based on the electric consumption, the system efficiency is 8.2. The comparative study of the hybrid system and vapor compression systems shows the superiority of the proposed system. Supplied by the geothermal sources of the Tunisian south, the system makes it possible to obtain for a pilot geothermal station, a production of 75 tons of ice per day. The greenhouse gas emissions should thus be reduced by about 2.38 tons of CO2 per day. Therefore, based on the typical geothermal energy sources in Tunisia which present a global refrigeration potential of 4.4 MW, the daily quantity of ice that could be produced is about 865 tons. The greenhouse gas emissions should thus be reduced by about 10,000 tons of CO2 per year.

  14. Exergoeconomic performance optimization for a steady-flow endoreversible refrigeration model including six typical cycles

    Lingen Chen, Xuxian Kan, Fengrui Sun, Feng Wu

    2013-01-01

    The operation of a universal steady flow endoreversible refrigeration cycle model consisting of a constant thermal-capacity heating branch, two constant thermal-capacity cooling branches and two adiabatic branches is viewed as a production process with exergy as its output. The finite time exergoeconomic performance optimization of the refrigeration cycle is investigated by taking profit rate optimization criterion as the objective. The relations between the profit rate and the temperature ra...

  15. Influence of irreversible losses on the performance of a two-stage magnetic Brayton refrigeration cycle

    The general performance characteristics of a two-stage magnetic Brayton refrigeration cycle consisting of three constant magnetic fields and three irreversible adiabatic processes are investigated. Based on the thermodynamic properties of a magnetic material and the irreversible cycle model of a two-stage Brayton refrigerator, expressions for the cooling load and coefficient of performance of the refrigeration system are derived. The influence of the finite-rate heat transfer in the heat exchange processes, irreversibilities in the three adiabatic processes, ratios of two magnetic fields in the three constant magnetic field processes, and heat leak losses between two heat reservoirs on the performance of the two-stage magnetic Brayton refrigeration cycle are analyzed in detail. Some important performance curves, which can reveal the general characteristics of the refrigeration system, are presented and the maximum values of cooling load and coefficient of performance are numerically calculated. The optimal choices and matches of other parameters at the maximum cooling load or the maximum coefficient of performance are discussed and the optimally operating regions of some important parameters in the refrigeration system are determined. The results obtained here are compared with those derived from other models of the magnetic Brayton refrigeration cycles, and consequently, the advantage of an inter-cooled process is expounded.

  16. Thermodynamic Analysis of Double-Stage Compression Transcritical CO2 Refrigeration Cycles with an Expander

    Zhenying Zhang; Lirui Tong; Xingguo Wang

    2015-01-01

    Four different double-compression CO2 transcritical refrigeration cycles are studied: double-compression external intercooler cycle (DCEI), double-compression external intercooler cycle with an expander (DCEIE), double-compression flash intercooler cycle (DCFI), double-compression flash intercooler cycle with an expander (DCFIE). The results showed that the optimum gas cooler pressure and optimum intermediate pressure of the flash intercooler cycles are lower than that of the external interco...

  17. Thermoeconomic optimization of subcooled and superheated vapor compression refrigeration cycle

    An exergy-based thermoeconomic optimization application is applied to a subcooled and superheated vapor compression refrigeration system. The advantage of using the exergy method of thermoeconomic optimization is that various elements of the system-i.e., condenser, evaporator, subcooling and superheating heat exchangers-can be optimized on their own. The application consists of determining the optimum heat exchanger areas with the corresponding optimum subcooling and superheating temperatures. A cost function is specified for the optimum conditions. All calculations are made for three refrigerants: R22, R134a, and R407c. Thermodynamic properties of refrigerants are formulated using the Artificial Neural Network methodology

  18. Reduction of Thermal Energy Loss in Cyclic Operation of Refrigeration Cycle

    Gommori, Masahiko; Kogure, Hiroshi; Hara, Toshitsugu

    Investigation of thermal energy loss in cyclic operation of refrigeration cycle in a refrigerator-freezer were made. The energy loss was found to consist of three parts ; hot gas-refrigerant entering loss, cooling lag loss, and evaporator superheat loss. Hot gas-refrigerant entering loss is occured when high temperature gaseous refrigerant in a condenser flows into an evaporator to heat up the refrigerant in it. Main results are as follows ; 1) Hot gas-refrigerant entering loss, which was the most dominant, was found to be from 7.6 to 12.3% (for reciprocationg compressor) and from 11.9 to 17.4% (for rotary compressor) of the cooling load, respectively. 2) The thermal energy loss was confirmed to be able to be reduced when hot gas-refrigerant was restricted to flow in the evaporator with control valves. It follows to reduce electrical power consumption by 10 and 15%, in the case of reciprocating compressor and of rotary compressor, respectively. 3) Cycle frequency was made to be optimized theoretically and experimentally in the case of with and without valves.

  19. Second law comparison of single effect and double effect vapour absorption refrigeration systems

    Gomri, Rabah [Engineering Faculty, Department of Genie Climatique, Constantine University, 25000 Constantine (Algeria)

    2009-05-15

    In this paper a comparative study between single effect and double effect absorption refrigeration systems with identical cold output is carried out. Simulation results were used to study the influence of the various operating parameters on the performance coefficient, the thermal loads of the components, exergetic efficiency (rational efficiency) and the total change in exergy of the two systems. It is concluded that the COP of double effect system is approximately twice the COP of single effect system but the exergetic efficiency of double effect system increase slightly compared to the exergetic efficiency of single effect system. It is found that for each condenser and evaporator temperature, there is an optimum generator temperature where the total change in exergy of the single effect and double effect absorption refrigeration systems is minimum. At this point the COP and exergetic efficiency of the systems become maximum. In this study and when the evaporation temperature is varied from 4 C to 10 C, condenser and absorber temperatures are varied from 33 C to 39 C and generator (HPG) temperature is varied from 60 C to 190 C the maximum COP values of the single effect refrigeration systems are in the range of 0.73-0.79 and for double effect refrigeration systems are in the range of 1.22-1.42. The maximum exergetic efficiency values of the single effect refrigeration systems are in the range of 12.5-23.2% and for double effect refrigeration systems are in the range of 14.3-25.1%. (author)

  20. Optimal configuration for a finite low-temperature source refrigerator cycle with heat transfer law

    Jun Li, Lingen Chen, Yanlin Ge, Fengrui Sun

    2016-01-01

    Full Text Available The optimal configuration of a refrigeration cycle operating between a finite low-temperature source and an infinite high-temperature sink are derived by using finite time thermodynamics based on a complex heat transfer law, including Newtonian heat transfer law, linear phenomenological heat transfer law, radiative heat transfer law, Dulong-Petit heat transfer law, generalized convective heat transfer law and generalized radiative heat transfer law. In the refrigeration cycle model the only irreversibility of finite rate heat transfer is considered. The optimal relation between cooling load and coefficient of performance (COP of the refrigeration cycle is also derived by using an equivalent temperature of low-temperature source. The obtained results include those with various heat transfer laws and infinite low-temperature source, and can provide some theoretical guidelines for the designs of practical refrigerators.

  1. Optimal design of solid oxide fuel cell, ammonia-water single effect absorption cycle and Rankine steam cycle hybrid system

    Mehrpooya, Mehdi; Dehghani, Hossein; Ali Moosavian, S. M.

    2016-02-01

    A combined system containing solid oxide fuel cell-gas turbine power plant, Rankine steam cycle and ammonia-water absorption refrigeration system is introduced and analyzed. In this process, power, heat and cooling are produced. Energy and exergy analyses along with the economic factors are used to distinguish optimum operating point of the system. The developed electrochemical model of the fuel cell is validated with experimental results. Thermodynamic package and main parameters of the absorption refrigeration system are validated. The power output of the system is 500 kW. An optimization problem is defined in order to finding the optimal operating point. Decision variables are current density, temperature of the exhaust gases from the boiler, steam turbine pressure (high and medium), generator temperature and consumed cooling water. Results indicate that electrical efficiency of the combined system is 62.4% (LHV). Produced refrigeration (at -10 °C) and heat recovery are 101 kW and 22.1 kW respectively. Investment cost for the combined system (without absorption cycle) is about 2917 kW-1.

  2. Performance comparison between a conventional vapor compression and compression-absorption single-stage and double-stage systems used for refrigeration

    This study reports a comparison from the first and second law of thermodynamics of a conventional vapor compression cooling system, a compression-absorption single-stage (CASS) system, and a compression-absorption double-stage (CADS) system operating with CO2 and R134a in the compression cycle and H2O/LiBr in the absorption cycles. The CADS system is being by the first time proposed in the literature. The performance of the systems were analyzed as function of diverse operating parameters. It was found that the electrical energy consumption in the refrigeration cycles was about 45% lower than in the classical compression refrigeration cycles using CO2 and R134a as refrigerants under the same operating conditions. The results showed that the COP for the CADS could be 50% higher than those obtained with the CASS system. The systems operating with R134a always achieved higher COP than those obtained using CO2. From the exergy analysis it was clear that the highest irreversibilities occurs in the absorber and the evaporator for both mixtures. It was also found that the irreversibilities of the proposed system using R134a in the compression cycle were 17% lower than those obtained with the system using CO2 - Highlights: • A compression-absorption double-stage (CADS) system is by the first time proposed. • The compression power in cascade cycles was 45% lower than in compression cycles. • The COP for proposed system was up to 45.2% higher than those with other systems. • The systems operating with R134a achieved higher COP than those obtained using CO2. • The irreversibilities for the CADS using R134a were 17% lower than using CO2

  3. Thermodynamic analysis of an absorption refrigeration machine with new working fluid for solar applications

    Karno, Ali; Ajib, Salman

    2008-05-01

    A theoretical analysis was undertaken to examine the efficiency characteristics of acetone-zinc bromide solutions for an absorption refrigeration machine, using low generator temperatures (47 60°C), which allows the use of flat plate solar collectors. The results of the simulation were confirmed with an experimental investigation. The main results showed that the solution is well suited to operate the machine at low temperatures (higher than 50°C).

  4. Coherence-assisted single-shot cooling by quantum absorption refrigerators

    Mitchison, Mark T.; Woods, Mischa P.; Prior, Javier; Huber, Marcus

    2015-01-01

    The extension of thermodynamics into the quantum regime has received much attention in recent years. A primary objective of current research is to find thermodynamic tasks which can be enhanced by quantum mechanical effects. With this goal in mind, we explore the finite-time dynamics of absorption refrigerators composed of three qubits. The aim of this finite-time cooling is to reach low temperatures as fast as possible and subsequently extract the cold particle to exploit it for information ...

  5. Thermodynamic performance analysis of gas-fired air-cooled adiabatic absorption refrigeration systems

    In China, the application of small size gas-fired air-cooled absorption refrigeration systems as an alternative for electric compression air conditioning systems has shown broad prospects due to occurrence of electricity peak demand in Chinese big cities and lack of water resources. However, for conventional air-cooled absorption refrigeration systems, it is difficult to enhance the heat and mass transfer process in the falling film absorber, and may cause problems, for example, remarkable increase of pressure, temperature and concentration in the generators, risk of crystallization, acceleration of corrosion, degradation of performance, and so on. This paper presents a gas-fired air-cooled adiabatic absorption refrigeration system using lithium bromide-water solutions as its working fluid, which is designed with a cooling capacity of 16 kW under standard conditions. The system has two new features of waste heat recovery of condensed water from generator and an adiabatic absorber with an air cooler. Performance simulation and characteristic analysis are crucial for the optimal control and reliability of operation in extremely hot climates. A methodology is presented to simulate thermodynamic performance of the system. The influences of outdoor air temperature on operation performances of the system are investigated

  6. Effect Of Operational Parameters On Heat and Mass Transfer In Generator of R134a/DMF Absorption Refrigeration System

    Annamalai, Mani; Pasupathy, Balamurugan

    2012-01-01

    Vapour absorption refrigeration systems (VARS) has regained the attention due to their potential for renewable/waste heat utilization. To improve the efficiency of these systems, it becomes obligatory to make component level studies on processes. In this present study, investigations on the heat and mass transfer in compact generator of the vapour absorption refrigeration system have been carried out using R134a-Dimethyl formamide (DMF). An experimental facility of VARS has been fabricated us...

  7. The performance characteristics of an irreversible quantum Otto harmonic refrigeration cycle

    2009-01-01

    In this paper, an irreversible quantum Otto refrigeration cycle working with harmonic systems is established. Base on Heisenberg quantum master equation, the equations of motion for the set of harmonic systems thermodynamic observables are derived. The simulated diagrams of the quantum Otto refrigeration cycle are plotted. The relationship between average power of friction, cooling rate, power input, and the time of adiabatic process is analyzed by using numerical calculation. Moreover, the influence of the heat conductance and the time of iso-frequency process on the performance of the cycle is discussed.

  8. The performance characteristics of an irreversible quantum Otto harmonic refrigeration cycle

    HE JiZhou; HE Xian; TANG Wei

    2009-01-01

    In this paper,an irreversible quantum Otto refrigeration cycle working with harmonic systems is estab-lished.Base on Heisenberg quantum master equation,the equations of motion for the set of harmonic systems thermodynamic observables are derived.The simulated diagrams of the quantum Otto refrig-eration cycle are plotted.The relationship between average power of friction,cooling rate,power input,and the time of adiabatic process is analyzed by using numerical calculation.Moreover,the influence of the heat conductance and the time of iso-frequency process on the performance of the cycle is dis-cussed.

  9. Optimal analysis on the performance of an irreversible harmonic quantum Brayton refrigeration cycle.

    Lin, Bihong; Chen, Jincan

    2003-11-01

    An irreversible model of a quantum refrigeration cycle working with many noninteracting harmonic oscillators is established. The refrigeration cycle consists of two adiabatic and two constant-frequency processes. The general performance characteristics of the cycle are investigated, based on the quantum master equation and the semigroup approach. The expressions for several important performance parameters such as the coefficient of performance, cooling rate, power input, and rate of entropy production are derived. By using numerical solutions, the cooling rate of the refrigeration cycle subject to finite cycle duration is optimized. The maximum cooling rate and the corresponding parameters are calculated numerically. The optimal region of the coefficient of performance and the optimal ranges of temperatures of the working substance and times spent on the two constant-frequency processes are determined. Moreover, the optimal performance of the cycle in the high-temperature limit is compared with that of a classical Brayton refrigerator working with an ideal gas. The results obtained here show that in the high-temperature limit a harmonic quantum Brayton cycle may be equivalent to a classical Brayton cycle. PMID:14682856

  10. Simulation of an air conditioning absorption refrigeration system in a co-generation process combining a proton exchange membrane fuel cell

    Pilatowsky, I.; Gamboa, S.A.; Rivera, W. [Centro de Investigacion en Energia - UNAM, Temixco, Morelos (Mexico); Romero, R.J. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas - UAEM, Cuernavaca, Morelos (Mexico); Isaza, C.A. [Universidad Pontificia Bolivariana, Medellin (Colombia). Instituto de Energia y Termodinamica; Sebastian, P.J. [Centro de Investigacion en Energia - UNAM, Temixco, Morelos (Mexico); Cuerpo Academico de Energia y Sustentabilidad-UP Chiapas, Tuxtla Gutierrez, Chiapas (Mexico); Moreira, J. [Cuerpo Academico de Energia y Sustentabilidad-UP Chiapas, Tuxtla Gutierrez, Chiapas (Mexico)

    2007-10-15

    In this work, a computer simulation program was developed to determine the optimum operating conditions of an air conditioning system during the co-generation process. A 1 kW PEMFC was considered in this study with a chemical/electrical theoretical efficiency of 40% and a thermal efficiency of 30% applying an electrical load of 100%. A refrigeration-absorption cycle (RAC) operating with monomethylamine-water solutions (MMA-WS), with low vapor generation temperatures (up to 80 C) is proposed in this work. The computer simulation was based on the refrigeration production capacity at the maximum power capacity of the PEMFC. Heat losses between the fuel cell and the absorption air conditioning system at standard operating conditions were considered to be negligible. The results showed the feasibility of using PEMFC for cooling, increasing the total efficiency of the fuel cell system. (author)

  11. Exergy analysis, parametric analysis and optimization for a novel combined power and ejector refrigeration cycle

    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.

  12. Exergoeconomic performance optimization for a steady-flow endoreversible refrigeration model including six typical cycles

    Chen, Lingen; Kan, Xuxian; Sun, Fengrui; Wu, Feng [College of Naval Architecture and Power, Naval University of Engineering, Wuhan 430033 (China)

    2013-07-01

    The operation of a universal steady flow endoreversible refrigeration cycle model consisting of a constant thermal-capacity heating branch, two constant thermal-capacity cooling branches and two adiabatic branches is viewed as a production process with exergy as its output. The finite time exergoeconomic performance optimization of the refrigeration cycle is investigated by taking profit rate optimization criterion as the objective. The relations between the profit rate and the temperature ratio of working fluid, between the COP (coefficient of performance) and the temperature ratio of working fluid, as well as the optimal relation between profit rate and the COP of the cycle are derived. The focus of this paper is to search the compromised optimization between economics (profit rate) and the utilization factor (COP) for endoreversible refrigeration cycles, by searching the optimum COP at maximum profit, which is termed as the finite-time exergoeconomic performance bound. Moreover, performance analysis and optimization of the model are carried out in order to investigate the effect of cycle process on the performance of the cycles using numerical example. The results obtained herein include the performance characteristics of endoreversible Carnot, Diesel, Otto, Atkinson, Dual and Brayton refrigeration cycles.

  13. Exergoeconomic performance optimization for a steady-flow endoreversible refrigeration model including six typical cycles

    Lingen Chen, Xuxian Kan, Fengrui Sun, Feng Wu

    2013-01-01

    Full Text Available The operation of a universal steady flow endoreversible refrigeration cycle model consisting of a constant thermal-capacity heating branch, two constant thermal-capacity cooling branches and two adiabatic branches is viewed as a production process with exergy as its output. The finite time exergoeconomic performance optimization of the refrigeration cycle is investigated by taking profit rate optimization criterion as the objective. The relations between the profit rate and the temperature ratio of working fluid, between the COP (coefficient of performance and the temperature ratio of working fluid, as well as the optimal relation between profit rate and the COP of the cycle are derived. The focus of this paper is to search the compromised optimization between economics (profit rate and the utilization factor (COP for endoreversible refrigeration cycles, by searching the optimum COP at maximum profit, which is termed as the finite-time exergoeconomic performance bound. Moreover, performance analysis and optimization of the model are carried out in order to investigate the effect of cycle process on the performance of the cycles using numerical example. The results obtained herein include the performance characteristics of endoreversible Carnot, Diesel, Otto, Atkinson, Dual and Brayton refrigeration cycles.

  14. A Preisach-Based Nonequilibrium Methodology for Simulating Performance of Hysteretic Magnetic Refrigeration Cycles

    Brown, Timothy D.; Bruno, Nickolaus M.; Chen, Jing-Han; Karaman, Ibrahim; Ross, Joseph H.; Shamberger, Patrick J.

    2015-09-01

    In giant magnetocaloric effect (GMCE) materials a large entropy change couples to a magnetostructural first-order phase transition, potentially providing a basis for magnetic refrigeration cycles. However, hysteresis loss greatly reduces the availability of refrigeration work in such cycles. Here, we present a methodology combining a Preisach model for rate-independent hysteresis with a thermodynamic analysis of nonequilibrium phase transformations which, for GMCE materials exhibiting hysteresis, allows an evaluation of refrigeration work and efficiency terms for an arbitrary cycle. Using simplified but physically meaningful descriptors for the magnetic and thermal properties of a Ni45Co5Mn36.6In13.4 at.% single-crystal alloy, we relate these work/efficiency terms to fundamental material properties, demonstrating the method's use as a materials design tool. Following a simple two-parameter model for the alloy's hysteresis properties, we compute and interpret the effect of each parameter on the cyclic refrigeration work and efficiency terms. We show that hysteresis loss is a critical concern in cycles based on GMCE systems, since the resultant lost work can reduce the refrigeration work to zero; however, we also find that the lost work may be mitigated by modifying other aspects of the transition, such as the width over which the one-way transformation occurs.

  15. Quantum refrigeration cycles using spin-1/2 systems as the working substance.

    He, Jizhou; Chen, Jincan; Hua, Ben

    2002-03-01

    The cycle model of a quantum refrigerator composed of two isothermal and two isomagnetic field processes is established. The working substance in the cycle consists of many noninteracting spin-1/2 systems. The performance of the cycle is investigated, based on the quantum master equation and semigroup approach. The general expressions of several important performance parameters, such as the coefficient of performance, cooling rate, and power input, are given. Especially, the case at high temperatures is analyzed in detail. The results obtained are further generalized and discussed, so that they may be directly used to describe the performance of the quantum refrigerator using spin-J systems as the working substance. Finally, the optimum characteristics of the quantum Carnot refrigerator are derived simply. PMID:11909203

  16. Small quantum absorption refrigerator in the transient regime: Time scales, enhanced cooling, and entanglement

    Brask, Jonatan Bohr; Brunner, Nicolas

    2015-12-01

    A small quantum absorption refrigerator, consisting of three qubits, is discussed in the transient regime. We discuss time scales for coherent dynamics, damping, and approach to the steady state, and we study cooling and entanglement. We observe that cooling can be enhanced in the transient regime, in the sense that lower temperatures can be achieved compared to the steady-state regime. This is a consequence of coherent dynamics but can occur even when this dynamics is strongly damped by the dissipative thermal environment, and we note that precise control over couplings or timing is not needed to achieve enhanced cooling. We also show that the amount of entanglement present in the refrigerator can be much larger in the transient regime compared to the steady state. These results are of relevance to future implementations of quantum thermal machines.

  17. Optimization of the performance characteristics in an irreversible regeneration magnetic Brayton refrigeration cycle

    Wang, Hao; Wu, GuoXing

    2012-02-01

    A model of the irreversible regenerative Brayton refrigeration cycle working with paramagnetic materials is established, in which the regeneration problem in two constant-magnetic field processes and the irreversibility in two adiabatic processes are considered synthetically. Expressions for the COP, cooling rate, power input, the minimum ratio of the two magnetic fields, etc., are derived. It is found that the influence of the irreversibility and the regeneration on the main performance parameters of the magnetic Brayton refrigerator is remarkable. It is important that we have obtained several optimal criteria, which may provide some theoretical basis for the optimal design and operation of the Brayton refrigerator. The results obtained in the paper can provide some new theoretical information for the optimal design and performance improvement of real Brayton refrigerators.

  18. Simplified Helium Refrigerator Cycle Analysis Using the `Carnot Step'

    P. Knudsen; V. Ganni

    2006-05-01

    An analysis of the Claude form of an idealized helium liquefier for the minimum input work reveals the ''Carnot Step'' for helium refrigerator cycles. As the ''Carnot Step'' for a multi-stage polytropic compression process consists of equal pressure ratio stages; similarly for an idealized helium liquefier the ''Carnot Step'' consists of equal temperature ratio stages for a given number of expansion stages. This paper presents the analytical basis and some useful equations for the preliminary examination of existing and new Claude helium refrigeration cycles.

  19. Thermodynamic performance analysis of a vapor compression–absorption cascaded refrigeration system

    Highlights: • Study includes first and second law analysis with alternatives refrigerants. • Power consumption in cascaded system is 61% less than vapor compression system. • COP of compression system is improved by 155% with cascaded absorption system. • Condenser is more sensitive to external fluid temperature as compare to evaporator. - Abstract: In the present study, a thermodynamic model for cascaded vapor compression–absorption system (CVCAS) has been developed which consists of a vapor compression refrigeration system (VCRS) coupled with single effect vapor absorption refrigeration system (VARS). Based on first and second laws, a comparative performance analysis of CVCAS and an independent VCRS has been carried out for a design capacity of 66.67 kW. The results show that the electric power consumption in CVCAS is reduced by 61% and COP of compression section is improved by 155% with respect to the corresponding values pertaining to a conventional VCRS. However there is a trade-off between these parameters and the rational efficiency which is found to decrease to half of that for a VCRS. The effect of various operating parameters, i.e., superheating, subcooling, cooling capacity, inlet temperature and the product of effectiveness and heat capacitance of external fluids are extensively studied on the COP, total irreversibility and rational efficiency of the CVCAS. Besides, the performance of environment friendly refrigerants such as R410A, R407C and R134A is found to be almost at par with that of R22. Hence, all the alternative refrigerants selected herein can serve as potential substitutes for R22. Furthermore, it has been found that reducing the irreversibility rate of the condenser by one unit due to decrease in condenser temperature depicted approximately 3.8 times greater reduction in the total irreversibility rate of the CVCAS, whereas unit reduction in the evaporator’s irreversibility rate due to increase in evaporator temperature reduced

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

    Zhenying Zhang; Lili Tian

    2014-01-01

    The impulse turbo expander (ITE) is employed to replace the throttling valve in the vapor compression refrigeration cycle to improve the system performance. An improved ITE and the corresponding cycle are presented. In the new cycle, the ITE not only acts as an expansion device with work extraction, but also serves as an economizer with vapor injection. An increase of 20% in the isentropic efficiency can be attained for the improved ITE compared with the conventional ITE owing to the reductio...

  1. First Law Analysis of a Two-stage Ejector-vapor Compression Refrigeration Cycle working with R404A

    Feiza Memet; Daniela-Elena Mitu

    2011-01-01

    The traditional two-stage vapor compression refrigeration cycle might be replaced by a two-stage ejector-vapor compression refrigeration cycle if it is aimed the decrease of irreversibility during expansion. In this respect, the expansion valve is changed with an ejector. The performance improvement is searched in the case of choosing R404A as a refrigerant. Using the ejector as an expansion device ensures a higher value for COP compared to the traditional case. On the basis...

  2. Experimental simulation of a magnetic refrigeration cycle in high magnetic fields

    Dilmieva, E. T.; Kamantsev, A. P.; Koledov, V. V.; Mashirov, A. V.; Shavrov, V. G.; Cwik, J.; Tereshina, I. S.

    2016-01-01

    The complete magnetic refrigeration cycle has been simulated on a sample of gadolinium in magnetic fields of a Bitter coil magnet up to 12 T. The total change of temperature of the sample during the cycle is a consequence of magnetic refrigeration, and the dependence of the magnetization of the sample on the magnetic field exhibits a hysteretic behavior. This makes it possible to determine the work done by the magnetic field on the sample during the magnetic refrigeration cycle and to calculate the coefficient of performance of the process. In a magnetic field of 2 T near the Curie temperature of gadolinium, the coefficient of performance of the magnetic refrigeration is found to be 92. With an increase in the magnetic field, the coefficient of performance of the process decreases sharply down to 15 in a magnetic field of 12 T. The reasons, for which the coefficient of performance of the magnetic refrigeration is significantly below the fundamental limitations imposed by the reversed Carnot theorem, have been discussed.

  3. NLP model based thermoeconomic optimization of vapor compression–absorption cascaded refrigeration system

    Highlights: • It addresses the size and cost estimation of cascaded refrigeration system. • Cascaded system is a promising decarburizing and energy efficient technology. • Second law analysis is carried out with modified Gouy-Stodola equation. • The total annual cost of plant operation is optimized in present work. - Abstract: This paper addresses the size and cost estimation of vapor compression–absorption cascaded refrigeration system (VCACRS) for water chilling application taking R410a and water–LiBr as refrigerants in compression and absorption section respectively which can help the design engineers in manufacturing and experimenting on such kind of systems. The main limitation in the practical implementation of VCACRS is its size and cost which are optimized in the present work by implementing Direct Search Method in non-linear programming (NLP) mathematical model of VCACRS. The main objective of optimization is to minimize the total annual cost of system which comprises of costs of exergy input and capital costs in monetary units. The appropriate set of decision variables (temperature of evaporator, condenser, generator, absorber, cascade condenser, degree of overlap and effectiveness of solution heat exchanger) minimizes the total annual cost of VCACRS by 11.9% with 22.4% reduction in investment cost at the base case whereas the same is reduced by 7.5% with 11.7% reduction in investment cost with reduced rate of interest and increased life span and period of operation. Optimization results show that the more investment cost in later case is well compensated through the performance and operational cost of the system. In the present analysis, optimum cascade condensing temperature is a strong function of period of operation and capital recovery factor. The cascading of compression and absorption systems becomes attractive for lower rate of interest and increase life span and operational period

  4. Design, Fabrication and Performance Evaluation of a Micro-Absorption Refrigerator

    Hyginus .U. Ugwu

    2012-11-01

    Full Text Available Developments in absorption cooling technology present an opportunity to achieve significant improvements on micro-scale to buildings, cooling, heating and power systems for residential and light commercial buildings. Their resultant effects are effective, energy efficient and economical. This study therefore contributes an important knowledge and method in the development, fabrication and application of an absorption refrigerator as a better alternative to the commonly used compressor refrigerators. In its embodiment, the work focuses on the design and fabrication of the absorption chiller system with low or no vibration since there are virtually no moving parts. Also, it dovetailed into the selection of a suitable refrigerant that is economically friendly in order to reduce or eliminate its ozone depleting effect. Consequently, the design was fabricated using adapted locally sourced materials. This is to encourage local ingenuity and to reduce cost of production comparable to already made custom-imported ones. It is designed to be simple, handy and readily available to be used by anyone in case of malfunctioning and for easy relocation. Though, the main limitation of the system fabricated is the long time it uses to achieve cooling, the performance of the machine generally is very efficient as its calculated coefficient of performance ( C.O.P is 1.21, which compared favourably well with the literature value of 1.00-2.00. Also, the total cost including an over-head of 30% of the machine was estimated at forty-one thousand, two hundred and fifty-nine (N41,259.40 naira, forty kobo only based on current price structure compared to an equivalent custom-made-imported type estimated at between sixty to seventy thousand (N60,000.00 to N70,000.00 naira. Hence, the machine is affordable to all, and is highly recommended for local entrepreneurs for mass production because of its cost effectiveness, simplicity and availability of spare parts.

  5. Analysis of engineering cycles power, refrigerating and gas liquefaction plant

    Haywood, R W

    1991-01-01

    Extensively revised, updated and expanded, the fourth edition of this popular text provides a rigorous analytical treatment of modern energy conversion plant. Notable for both its theoretical and practical treatment of conventional and nuclear power plant, and its studies of refrigerating and gas-liquefaction plant. This fourth edition now includes material on topics of increasing concern in the fields of energy 'saving' and reduction of environmental pollution. This increased coverage deals specifically with the following areas: CHP (cogeneration) plant, studies of both gas and coal burning p

  6. Theoretical evaluation on effect of internal heat exchanger in ejector expansion transcritical CO2 refrigeration cycle

    The performance of the transcritical CO2 refrigeration system requires further improvement in order to save energy. In this paper, the effect of the internal heat exchanger (IHE) on the performance of the ejector expansion transcritical CO2 refrigeration system is analyzed theoretically based on the first law of thermodynamics. The possible parameters affecting system efficiency are investigated. The variation of ejector entrainment ratio, pressure recovery, ejector efficiency and the coefficient of performance (COP) is obtained for the ejector expansion transcritical CO2 refrigeration cycles with and without IHE. It is found that the addition of IHE in the CO2 ejector refrigeration cycle increases the ejector entrainment ratio and the ejector efficiency, and decreases pressure recovery under the same gas cooler pressures. Unlike in a conventional throttle valve cycle, an IHE addition does not always improve the system performance in the ejector expansion cycle. Whether the energy efficiency of the ejector cycle by IHE can be improved depends on the isentropic efficiency level of the ejector. The utilization of IHE is only applicable in the cases of lower ejector isentropic efficiencies or higher gas cooler exit/evaporator temperatures for the ejector expansion system from the view of energy efficiency. - Highlights: ► The effect of internal heat exchanger on the performance of ejector transcritical CO2 refrigeration system is analyzed. ► The variation of entrainment ratio, pressure recovery, ejector efficiency and coefficient of performance is obtained. ► An internal heat exchanger does not always improve the system performance in the ejector expansion cycle. ► Whether the ejector cycle performance by internal heat exchanger can be improved depends on the ejector isentropic efficiency.

  7. Combined heat and power generation with exhaust-heated two-stage absorption refrigerator. Performance of a pilot installation with a refrigeration capacity of 350 kW; Kraft-Waerme-Kaelte-Kopplung mit Abgas-Beheizter zweistufiger Absorptionskaeltemaschine. Betriebserfahrungen einer Pilotinstallation mit 350 kW Kaelteleistung

    Plura, S.; Baumeister, D.; Koeberle, T.; Radspieler, M.; Schweigler, C. [Bayerisches Zentrum fuer Angewandte Energieforschung e.V. (ZAE Bayern), Garching (Germany)

    2007-07-01

    A new system concept for higher efficiency of cogeneration systems is developed in which a cogeneration unit is combined with a two-stage absorption refrigerator, and the waste heat of the cogeneration unit is directly passed on into the regenerator of the absorption refrigerator. The higher temperature level of the waste heat makes it possible to use a two-stage absorption cycle for higher energy efficiency. For simultaneous utilisation of low-temperature heat, the two-stage cycle is combined with a one-stage cycle for additional heat supply at a lower temperature level so that the exhaust of a typical cogeneration unit will be cooled to about 120 degC. At the same time, further waste heat of the cogeneration unit will be transferred to the heat pump via a hot water circuit. This concept with a combined single-stage and two-stage absorption circuit is referred to as a double-effect/single-effect circuit. The new system is used for energy supply in a spa, where the two-stage absorption refrigerator cools the water used for swimming pool cleaning with a refrigerating capacity of 350 kW and provides low-temperature heat for swimming pool heating with a capacity of 700 kW. (orig.)

  8. Performance evaluation of combined ejector LiBr/H2O absorption cooling cycle

    Hasan Sh. Majdi

    2016-03-01

    Full Text Available The objective of this work is to develop a computer simulation program to evaluate the performance of solar-assited combined ejector absorption (single-effect cooling system using LiBr/H2O as a working fluid and operating under steady-state conditions. The ejector possess no moving parts and is simple and reliable, which makes it attractive for combination with single-stage absorption cycle for further improvement to the system's performance. In this research, improvement to the system is achieved by utilizing the potential kinetic energy of the ejector to enhance refrigeration efficiency. The effects of the entrainment ratio of the ejector, operating temperature, on the thermal loads, and system performance have been investigated. The results showed that the evaporator and condenser loads, post-addition of the ejector, is found to be permanently higher than that in the basic cycle, which indicates a significant enhancement of the proposed cycle and the cooling capacity of the system increasing with the increase in evaporator temperature and entrainment ratio. The COP of the modified cycle is improved by up to 60 % compared with that of the basic cycle at the given condition. This process stabilizes the refrigeration system, enhanced its function, and enabled the system to work under higher condenser temperatures.

  9. The evaluation of a solar-driven aqua-ammonia diffusion absorption heating and cooling cycle / M.C. Potgieter.

    Potgieter, Marthinus Christiaan

    2013-01-01

    Several steps are followed in order to evaluate the cycle as the title suggests. The diffusion absorption refrigerator (DAR) cycle performance is evaluated when using helium or hydrogen as auxiliary gas. A slight increase in COP is found when using helium, but it is not sufficient to justify the cost. A secondary simulation of an alternate dual-pressure cycle using a pump is done as feasibility comparison with the same parameters as the diffusion cycle. It was found that the second cycle is n...

  10. Optimal household refrigerator replacement policy for life cycle energy, greenhouse gas emissions, and cost

    Although the last decade witnessed dramatic progress in refrigerator efficiencies, inefficient, outdated refrigerators are still in operation, sometimes consuming more than twice as much electricity per year compared with modern, efficient models. Replacing old refrigerators before their designed lifetime could be a useful policy to conserve electric energy and greenhouse gas emissions. However, from a life cycle perspective, product replacement decisions also induce additional economic and environmental burdens associated with disposal of old models and production of new models. This paper discusses optimal lifetimes of mid-sized refrigerator models in the US, using a life cycle optimization model based on dynamic programming. Model runs were conducted to find optimal lifetimes that minimize energy, global warming potential (GWP), and cost objectives over a time horizon between 1985 and 2020. The baseline results show that depending on model years, optimal lifetimes range 2-7 years for the energy objective, and 2-11 years for the GWP objective. On the other hand, an 18-year of lifetime minimizes the economic cost incurred during the time horizon. Model runs with a time horizon between 2004 and 2020 show that current owners should replace refrigerators that consume more than 1000 kWh/year of electricity (typical mid-sized 1994 models and older) as an efficient strategy from both cost and energy perspectives

  11. An Automated Ac Susceptibility Set up Fabricated Using a Closed-Cycle Helium Refrigerator

    Kundu, S

    2011-01-01

    We have described here the design and operation of an automated ac susceptibility set up using a closed cycle helium refrigerator. This set up is useful for measuring linear and nonlinear magnetic susceptibilities of various magnetic materials. The working temperature range is 2 K to 300 K. The overall sensitivity of the set up is found to be 10-3 emu.

  12. SUPERCONDUCTING MAGNET FOR 60 TONNE/HOUR MINERAL SEPARATOR WITH CLOSED CYCLE 4 KELVIN REFRIGERATION

    Good, J.; White, K.

    1984-01-01

    Cryogenic Consultants Limited has constructed a superconducting magnet system for magnetic separation, with a three metre long dipole magnet cooled by a closed-cycle refrigerator. This paper considers the design and construction of the magnet system in relation to a theoretical expression for processing capacity.

  13. Optimal thermoeconomic performance of an irreversible regenerative ferromagnetic Ericsson refrigeration cycle

    Xu, Zhichao; Guo, Juncheng; Lin, Guoxing; Chen, Jincan

    2016-07-01

    On the basis of the Langevin theory of classical statistical mechanics, the magnetization, entropy, and iso-field heat capacity of ferromagnetic materials are analyzed and their mathematical expressions are derived. An irreversible regenerative Ericsson refrigeration cycle by using a ferromagnetic material as the working substance is established, in which finite heat capacity rates of low and high temperature reservoirs, non-perfect regenerative heat of the refrigeration cycle, additional regenerative heat loss, etc. are taken into account. Based on the regenerative refrigeration cycle model, a thermoeconomic function is introduced as one objective function and optimized with respect to the temperatures of the working substance in the two iso-thermal processes. By means of numerical calculation, the effects of the effective factor of the heat exchangers in high/low temperature reservoir sides, efficiency of the regenerator, heat capacity rate of the low temperature reservoir, and applied magnetic field on the optimal thermoeconomic function as well as the corresponding cooling rate and coefficient of performance are revealed. The results obtained in this paper can provide some theoretical guidance for the optimal design of actual regenerative magnetic refrigerator cycle.

  14. Comparative study of cycle modification strategies for trans-critical CO2 refrigeration cycle for warm climatic conditions

    Simarpreet Singh; Nilesh Purohit; M.S. Dasgupta

    2016-01-01

    This paper presents a comparative study of performance of six prominent modifications on the basic trans-critical CO2 refrigeration system to investigate their suitability to high ambient temperature application (35–55 °C). To explore the application in chiller, domestic refrigeration and air cooling the evaporator temperature chosen are −10 °C, 0 °C and 10 °C respectively. In general the cycle modifications have a positive effect on the overall COP of the system. However, to comprehend pract...

  15. The optimal performance of a quantum refrigeration cycle working with harmonic oscillators

    The cycle model of a quantum refrigeration cycle working with many non-interacting harmonic oscillators and consisting of two isothermal and two constant-frequency processes is established. Based on the quantum master equation and semi-group approach, the general performance of the cycle is investigated. Expressions for some important performance parameters, such as the coefficient of performance, cooling rate, power input, and rate of the entropy production, are derived. Several interesting cases are discussed and, especially, the optimal performance of the cycle at high temperatures is discussed in detail. Some important characteristic curves of the cycle, such as the cooling rate versus coefficient of performance curves, the power input versus coefficient of performance curves, the cooling rate versus power input curves, and so on, are presented. The maximum cooling rate and the corresponding coefficient of performance are calculated. Other optimal performances are also analysed. The results obtained here are compared with those of an Ericsson or Stirling refrigeration cycle using an ideal gas as the working substance. Finally, the optimal performance of a harmonic quantum Carnot refrigeration cycle at high temperatures is derived easily

  16. Applications of closed cycle refrigerator for some physical experiments

    Full text: It is known that CCRs give a good possibility to conduct various experiments in a wide range of temperatures from 2.5 K up to 500 deg. C. These do not need nor liquid helium, nor liquid nitrogen and create a quick, precise and stable conditions for researchers. Some applications of such CCRs from Lake Shore corporation will be consider ed in this communication. The first one is a measurement of temperature dependence of the viscosity by drop-falling method of some special liquids which can be used in ultra cold neutron investigations. The second one is an experiment for receiving the perfect solid crystals of methane which are need in producing ultra cold neutrons in medium power reactors. For these experiments some special arrangements were installed on the cold head of refrigerator with long vertical or small round windows on the screens through which the processes studied were visually observed and measured. (authors)

  17. Thermodynamic Analysis of an Absorption/Compression Refrigeration System Using Geothermal Energy

    L. Kairouani

    2005-01-01

    Full Text Available This article presents the potential use and exploration of geothermal energy for cooling applications using a combined absorption/compression system. The considered system uses R134a for the compression part and the cool water-ammonia for the absorption part of the installation. The geothermal temperature source is in the range 343-349K, the condensation temperature is 308 K, and in order to produce ice, the R134a evaporation temperature is 263 K. The COP is about 5.4. Therefore, based on the typical geothermal energy sources in Tunisia which present a refrigeration potential power of 9.1 MW, the quantity of ice that could be produced is about 82 tons per hour. The greenhouse gas emissions should thus be reduced by about 5884 tons of CO2 per year, which represents (59%.

  18. Absorption refrigeration using waste heat; Refrigeracion por absorcion utilizando calor de desecho

    Heard, Christopher; Ayala, Ramon; Best, Roberto [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1994-07-01

    In this article a detailed analysis is made of the absorption refrigeration system that uses waste heat and because of being of low temperature, can make the processes more efficient being at the same time an important factor in the country`s energy resources saving, since the system permits to increase the availability of electricity and fuel`s energy. The Instituto de Investigaciones Electricas (IIE) and the Universidad Nacional Autonoma de Mexico (UNAM) absorption refrigeration experience is described and the economic aspects related with this system are analyzed. [Espanol] En este articulo se presenta un analisis detallado del sistema de refrigeracion por absorcion que utiliza calor de desecho y que, siendo de baja temperatura, puede hacer mas eficientes los procesos y ser a la vez un factor importante en el ahorro de los recursos energeticos del pais, pues el sistema permite aumentar la disponibilidad energetica de electricidad y combustibles. Se describe la experiencia del Instituto de Investigaciones Electricas (IIE) en refrigeracion por absorcion y la de la Universidad Nacional Autonoma de Mexico (UNAM), y se analizan los aspectos economicos relacionados con este sistema.

  19. Solution procedure and performance evaluation for a water–LiBr absorption refrigeration machine

    The water–lithium bromide absorption cooling machine was investigated theoretically in this paper. A detailed solution procedure was proposed and validated. A parametric study was conducted over the entire admissible ranges of the desorber, condenser, absorber and evaporator temperatures. The performance of the machine was evaluated based on the circulation ratio which is a measure of the system size and cost, the first law coefficient of performance and the second law exergy efficiency. The circulation ratio and the coefficient of performance were seen to improve as the temperature of the heat source increased, while the second law performance deteriorated. The same qualitative responses were obtained when the temperature of the refrigerated environment was increased. On the other hand, simultaneously raising the condenser and absorber temperatures was seen to result in a severe deterioration of both the circulation ratio and first law coefficient of performance, while the second law performance indicator improved significantly. The influence of the difference between the condenser and absorber exit temperatures, as well as that of the internal recovery heat exchanger on the different performance indicators was also calculated and discussed. - Highlights: • Analysis of a water–LiBr absorption machine, including detailed solution procedure. • Performance assessed using first and second law considerations, as well as flow ratio. • Effects of heat source and refrigerated environment temperatures on the performance. • Effects of the difference between condenser and absorber temperatures. • Effects of internal heat exchanger efficiency on overall cooling machine performance

  20. Definition of a reference dataset for life cycle consideration of refrigeration systems

    Mas Méndez, Roger

    2013-01-01

    In recent decades society has increased its concern about environmental protection, in order to achieve the goal of sustainable development. However, there are several economic sectors like refrigeration industry, which still are cause for a wide number of environmental impacts and, therefore, require improvement in their processes. The purpose of this final work is to establish the current state of the art regarding Life Cycle Assessment (LCA) and Life Cycle Costing (LCC), particularized to ...

  1. The Research on Programmable Control System of Lithium-Bromide Absorption Refrigerating Air Conditioner Based on the Network

    Sun Lunan

    2016-01-01

    Full Text Available This article regard the solar lithium-bromide absorption refrigerating air conditioning system as the research object, and it was conducting adequate research of the working principle of lithium bromide absorption refrigerating machine, also it was analyzing the requirements of control system about solar energy air conditioning. Then the solar energy air conditioning control system was designed based on PLC, this system was given priority to field bus control system, and the remote monitoring is complementary, which was combining the network remote monitoring technology. So that it realized the automatic control and intelligent control of new lithium bromide absorption refrigerating air conditioning system with solar energy, also, it ensured the control system can automatically detect and adjust when the external conditions was random changing, to make air conditioning work effectively and steadily, ultimately ,it has great research significance to research the air conditioning control system with solar energy.

  2. Numerical simulation of the effects of a suction line heat exchanger on vapor compression refrigeration cycle performance

    Most modern refrigerators incorporate heat transfer between the refrigerant in a capillary tube and the refrigerant in a suction line. This heat transfer is achieved by a non-adiabatic capillary tube called a capillary tube-suction line heat exchanger and is supposed to improve the performance of the small vapor compression refrigeration cycle by removing some enthalpy of the refrigerant at the evaporator entrance. To investigate the effects of this heat transfer on the refrigeration cycle, a computer program was developed based on conservation equations of mass, momentum, and energy. The non-adiabatic capillary tube model is based on a homogeneous two-phase flow model. The simulation results show that both the location and length of the heat exchange section influence the coefficient of performance (COP) as well as the cooling capacity. It is noteworthy that the influence was not monotonic; that is, the performance may be deteriorated under certain conditions

  3. Thermodynamic Analysis of Double-Stage Compression Transcritical CO2 Refrigeration Cycles with an Expander

    Zhenying Zhang

    2015-04-01

    Full Text Available Four different double-compression CO2 transcritical refrigeration cycles are studied: double-compression external intercooler cycle (DCEI, double-compression external intercooler cycle with an expander (DCEIE, double-compression flash intercooler cycle (DCFI, double-compression flash intercooler cycle with an expander (DCFIE. The results showed that the optimum gas cooler pressure and optimum intermediate pressure of the flash intercooler cycles are lower than that of the external intercooler cycle. The use of an expander in the DCEI cycle leads to a decrease of the optimum gas cooler pressure and little variation of the optimum intermediate pressure. However, the replacement of the throttle valve with an expander in the DCFI cycle results in little variation of the optimal gas cooler pressure and an increase of the optimum intermediate pressure. The DCFI cycle outperforms the DCEI cycle under all the chosen operating conditions. The DCEIE cycle outperforms the DCFIE cycle when the evaporating temperature exceeds 0 °C or the gas cooler outlet temperature surpasses 35 °C. When the gas cooler exit temperature varies from 32 °C to 48 °C, the DCEI cycle, DCEIE cycle, DCFI cycle and DCFIE cycle yield averaged 4.6%, 29.2%, 12.9% and 22.3% COP improvement, respectively, over the basic cycle.

  4. Application of exergy method to an irreversible inter-cooled refrigeration cycle

    Chen, C-K. [National Cheng-Kung University, Tainan (Taiwan). Department of Mechanical Engineering; Su, Y-F. [Far East College, Tainan (Taiwan). Department of Automation and Control Engineering

    2005-12-15

    The exergy method, based on the maximum exergetic efficiency criterion, has been applied to an irreversible inter-cooled refrigeration cycle. The exergetic efficiency defined as the ratio of the rate of exergy output to the rate of exergy input is taken as the objective function to be maximized. Multi-irreversibilities include finite-rate heat transfer, internal dissipation of the working fluid, and heat leaks between heat reservoirs. The maximum exergetic efficiency can be determined analytically by introducing the internal irreversibility parameter, which represents the degree of internal irreversibility. The corresponding performances of the irreversible refrigeration system are obtained simultaneously. The results show that the exergy method can be used as an effective criterion in designing an irreversible inter-cooled refrigeration system. (author)

  5. A comparative study of using simple and ejector-absorption refrigeration for inlet air cooling of simple and regenerative gas turbine

    Farshi, L.G.; Mahmoudi, S.M.S. [Tabriz Univ., Tabriz (Iran, Islamic Republic of). Faculty of Mechanical Engineering; Mosafa, A.H. [Islamic Azad Univ., Bonab (Iran, Islamic Republic of)

    2008-07-01

    A study was conducted in which the effect of inlet air cooling on the performance of a gas turbine was investigated. Compared to steam turbines, gas turbines have lower capital cost, are compact in size, and offer better environmental performance with fast starts and loading. They require less manpower for operating and do not need water sources. However, they have lower efficiency than steam turbines and have a strong influence on climatic conditions. In addition, thermal energy in the form of exhaust gases is delivered to, and wasted in, the environment. In order to increase the power and efficiency of gas turbine plants, this low grade thermal energy can be put to beneficial use in a heat exchanger of a regenerative gas turbine (RGT) or in the generator of an absorption refrigeration cycle (ARC). This paper focused on ways to increase the performance of gas turbine plants by using an ARC for inlet air cooling. The authors studied the feasibility of installing an ARC at the gas turbine inlet. The work showed that the net work and the efficiency will increase by 6-10 per cent and 1-5 per cent respectively for every 10 degrees C decrease of inlet temperature. Since the coefficient of performance (COP) of ARC is low, the thermal energy of exhaust gases cannot supply all the needed thermal energy for the refrigeration cycle. The results showed that when an ejector is included in the refrigeration cycle, the need for external energy source required for refrigeration cycle is reduced. 22 refs., 8 tabs., 18 figs.

  6. Optimum criteria of an irreversible quantum Brayton refrigeration cycle with an ideal Bose gas

    An irreversible cycle model of the quantum Brayton refrigeration cycle is established, in which finite-time processes and irreversibility in the two adiabatic processes are taken into account. On the basis of the thermodynamic properties of an ideal Bose gas, by using the optimal control-theory, the mathematical expressions for several important performance parameters, such as the coefficient of performance, power input and cooling load, are derived and some important performance parameters, e.g., the temperatures of the working substance at several important state-points, are optimized. By means of numerical predictions, the optimal performance characteristic curves of a Bose-Brayton refrigeration cycle are obtained and analyzed. Furthermore, some optimal operating regions including those for the cooling load, coefficient of performance and the temperatures of the cyclic working substance at the two important state-points are determined and evaluated. Finally, several special cases are discussed in detail

  7. A Comparative Cycle and Refrigerant Simulation Procedure Applied on Air-Water Heat Pumps

    Mader, Gunda; Palm, Björn; Elmegaard, Brian

    2012-01-01

    small capacity heat pump applications today. Many of the applicable refrigerants also reach their technical limits regarding low vapor pressure for very low source temperatures and high discharge temperatures for high sink temperatures. These issues are especially manifest for air-water heat pumps. Many...... alternative cycle setups and refrigerants are known to improve the energy efficiency of a vapor compression cycle and reduce discharge temperatures. However not all of them are feasible for small capacity heat pumps from a cost and complexity point of view. This paper presents a novel numerical approach......A vapor compression heat pump absorbs heat from the environment at a low temperature level and rejects heat at a high temperature level. The bigger the difference between the two temperature levels the more challenging is it to gain high energy efficiency with a basic cycle layout as found in most...

  8. Experimental results of a direct air-cooled ammonia–lithium nitrate absorption refrigeration system

    Absorption thermal cooling systems driven by renewable energy are a viable option in order to reduce fossil fuel consumption and the associated emissions. This work shows the results of an air cooled absorption cooling prototype working with an ammonia–lithium nitrate mixture at high ambient temperatures. An absorption refrigeration system was designed and built. The prototype is a one stage ammonia–lithium nitrate air cooled chiller. The experimental system was instrumented to evaluate each component. This paper shows the operation conditions in the experimental unit as well as some of the heat loads encountered at different operating conditions. The system was operated successfully at ambient temperatures in the range of 25–35 °C. A series of test showed that even at ambient temperatures it can be operated at evaporator temperatures below 10 °C producing chilled water for air conditioning applications such as radiative cooling panels. The system proved to stabilize very quickly and no risk of crystallization was encountered so the first results are promising in order to continue with the development of a more advanced prototype. - Highlights: •Experimental results of a direct air-cooled ammonia–lithium nitrate system. •The prototype is a one stage ammonia–lithium nitrate air cooled chiller. •The absorption system was operated successfully at ambient temperatures. •Cooling loads of 4.5 kW were reached in the chilled water side

  9. Impact of cycle-hysteresis interactions on the performance of giant magnetocaloric effect refrigerants

    Brown, T. D.; Karaman, I.; Shamberger, P. J.

    2016-07-01

    Magnetic refrigeration technology based on the giant magnetocaloric effect in solid-state refrigerants is known qualitatively to be limited by dissipative mechanisms accompanying hysteresis in the magneto-structural solid–solid phase transition. In this paper, we quantitatively explore the dependence of cycle performance metrics (cooling power, temperature span, work input, and fractional Carnot efficiency) on hysteresis properties (thermal hysteresis, one-way transition width) of the magneto-structural phase transition in a Ni45Co5Mn36.6In13.4 alloy system. We investigate a variety of Ericsson-type magnetic refrigeration cycles, using a Preisach-based non-equilibrium thermodynamic framework to model the evolution of the alloy's magnetic and thermal properties. Performance metrics are found to depend strongly on hysteresis parameters, regardless of the cycle chosen. However, for a given hysteresis parameter set, the material's transformation temperatures determine a unique cycle that maximizes efficiency. For the model system used undergoing Ericsson cycles with 5 and 1.5 {{T}} maximum field constraint, fractional Carnot efficiencies in excess of 0.9 require thermal hysteresis below 1.5 {{K}} and 0.5 {{K}}, respectively. We conclude briefly with some general materials considerations for mitigating these hysteresis inefficiencies through microstructure design and other materials processing strategies.

  10. Exergy and Structural Analysis of an Absorption Cooling Cycle and the Effect of Efficiency Parameters

    Miquel Nogués

    2005-12-01

    Full Text Available

    Absorption cycles are an alternative to compression cycles in cooling and refrigeration applications. Our analysis of an absorption cycle is based on the exergy and the structural analysis. Once the exergy analysis has been achieved, the coefficients of structural bonds (CSBs of the main heat and mass exchangers can be determined by a structural analysis. The CSBs show how the modification of the irreversibility of one component, by means of a variation of its efficiency, affects the whole cycle. It will be wise to put much of the design effort in improving the efficiency of a component, knowing that a slight decrease of the irreversibility of that component, thanks to a higher efficiency, results in an important improvement in the total irreversibility of the cycle. This methodology is applied to a single effect ammonia-water absorption cooling cycle. We also study how the selection of efficiency parameters affects the results comparing CSBs of heat exchangers obtained from the minimum temperature differences or the UA-values.

    Results show that the UA is a more suitable parameter than the minimum temperature difference. Concerning the CSB values, we obtain very high values for the refrigerant heat exchanger. Values above one are also observed for the absorber, condenser and generator.

    Lower values are found for the generator and the solution heat exchanger. A more detailed analysis should investigate the dependence of the CSB values on the range of efficiencies. As a further step, these results could be used in the thermoeconomic analysis and economical optimization.

  11. Modeling and Control of a Double-effect Absorption Refrigerating Machine

    Hihara, Eiji; Yamamoto, Yuuji; Saito, Takamoto; Nagaoka, Yoshikazu; Nishiyama, Noriyuki

    For the purpose of impoving the response to cooling load variations and the part load characteristics, the optimal operation of a double-effect absorption refrigerating machine was investigated. The test machine was designed to be able to control energy input and weak solution flow rate continuously. It is composed of a gas-fired high-temperature generator, a separator, a low-temperature generator, an absorber, a condenser, an evaporator, and high- and low-temperature heat exchangers. The working fluid is Lithium Bromide and water solution. The standard output is 80 kW. Based on the experimental data, a simulation model of the static characteristics was developed. The experiments and simulation analysis indicate that there is an optimal weak solution flow rate which maximizes the coefficient of performance under any given cooling load condition. The optimal condition is closely related to the refrigerant steam flow rate flowing from the separator to the high temperature heat exchanger with the medium solution. The heat transfer performance of heat exchangers in the components influences the COP. The change in the overall heat transfer coefficient of absorber has much effect on the COP compared to other components.

  12. Thermodynamic and thermo-economic analysis and optimization of performance of irreversible four-temperature-level absorption refrigeration

    Highlights: • The feasibility of performance of four-heat-source irreversible refrigerators is investigated. • The latter is achieved using NSGA algorithm and thermodynamic analysis. • Three well known decision makers are accomplished to indicate optimum outputs obtained with optimization process. - Abstract: This paper presents a developed ecological function for absorption refrigerators with four-temperature-level. Moreover, aforementioned absorption refrigerator is optimized by implementing ecological function. With the aim of the first and second laws of thermodynamics, an equivalent system is initially determined. To reach the addressed goal of this research, three objective functions that the coefficient of performance (COP), the ecological function (E) and thermoeconomic criterion (F) have been involved in optimization process simultaneously. Three objective functions are maximized at the same time. Developed multi objective evolutionary approaches (MOEAs) on the basis of NSGA-II method is implemented throughout this work

  13. Improving Energy Efficiency of a Refrigeration System with a Rankine Cycle and an Expander

    Subiantoro, Alison

    2015-01-01

    A method to increase energy efficiency of a vapor compression refrigeration system by using a Rankine cycle and an expander is studied. The systems studied include the R134a and the transcritical CO2 cycles with a 5 kW capacity. The working fluids of the Rankine cycle are R134a, propane and R123. The available heat input power is 1-5 kW. The results show that in the R134a and CO2 systems, 18-40% and 30-67% improvements of Coefficient of Performance (COP), respectively, can be achieved. The me...

  14. Coherence-assisted single-shot cooling by quantum absorption refrigerators

    Mitchison, Mark T.; Woods, Mischa P.; Prior, Javier; Huber, Marcus

    2015-11-01

    The extension of thermodynamics into the quantum regime has received much attention in recent years. A primary objective of current research is to find thermodynamic tasks which can be enhanced by quantum mechanical effects. With this goal in mind, we explore the finite-time dynamics of absorption refrigerators composed of three quantum bits (qubits). The aim of this finite-time cooling is to reach low temperatures as fast as possible and subsequently extract the cold particle to exploit it for information processing purposes. We show that the coherent oscillations inherent to quantum dynamics can be harnessed to reach temperatures that are colder than the steady state in orders of magnitude less time, thereby providing a fast source of low-entropy qubits. This effect demonstrates that quantum thermal machines can surpass classical ones, reminiscent of quantum advantages in other fields, and is applicable to a broad range of technologically important scenarios.

  15. COP Prediction of an ejector refrigeration cycle combined with a vapour compression cycle for automotive air conditioning

    Nat Suvarnakuta

    2014-03-01

    Full Text Available This paper presents the COP prediction of an ejector refrigeration cycle combined with a vapour compression cycle for automotive air conditioning. Using computational fluid dynamics (CFD technique, the performance of an ejector was analyzed in term of the entrainment ratio (Rm and critical back pressure (CBP. The results from this study were compared with a previous study of combined ejector refrigeration system for automotive air conditioning application [1] which the entrainment ratio (Rm were predicted from one-dimensional (1-D equation. The performance of an ejector (Rm and CBP from CFD and onedimensional method were analyzed and used as database for a mathematical modeling. In order to predict the COP of the combined system, a set of mathematical equations was developed using EES. The operating conditions are chosen accordingly as, intercooler temperature between 15 ๐ C and 25 ๐ C, condenser temperature equal to 35 ๐ C and evaporator temperature equal to 5 ๐ C. However, when generator temperatures are 80 ๐ C, 85 ๐ C and 90 ๐ C, the results showed average relative errors of the COP of an ejector refrigeration cycle (COPej, between CFD and 1-D are 44.64%, 50.47% and 59.68% respectively, and between CFD and 1-D NEW are 1.54%, 0.08% and 6.49% respectively.

  16. Performance of V-type Stirling-cycle refrigerator for different working fluids

    Tekin, Yusuf; Ataer, Omer Ercan [Erciyes University, Engineering Faculty, Mechanical Engineering Department, Melikgazi, 38 039 Kayseri (Turkey)

    2010-01-15

    The thermodynamic analysis of a V-type Stirling-cycle Refrigerator (VSR) is performed for air, hydrogen and helium as the working fluid and the performance of the VSR is investigated. The V-type Stirling-cycle refrigerator consists of expansion and compression spaces, cooler, heater and regenerator, and it is assumed that the control volumes are subjected to a periodic mass flow. The basic equations of the VSR are derived for per unit crank angle, so time does not appear in the equations. A computer program is prepared in FORTRAN, and the basic equations are solved iteratively. The mass, temperature and density of working fluid in each control volume are calculated for different charge pressures, engine speeds, and for fixed heater and cooler surface temperatures. The work, instantaneous pressure and the COP of the VSR are calculated. The results are obtained for different working fluids, and given by diagrams. (author)

  17. Industrial refrigeration with high efficiency absorption; Refrigeracion industrial por absorcion de alta eficiencia

    Ayala Delgado, R.; Heard, C. L. [Instituto de Investigaciones Electricas, Cuernavaca, (Mexico); Pardubicki, J. [LAJ International, Mexico D. F. (Mexico)

    1995-12-31

    The absorption refrigeration ammonia-lithium nitrate offers great advantages compared with the mechanical compression refrigeration with ammonia as well as with the absorption ammonia-water refrigeration. With heat temperatures of 1000 to 1400 Celsius degrees, for instance low pressure steam the generation of cold at low temperatures (-100 to -200 Celsius degrees) is possible. The system has less components and is much less expensive than the ammonia-water equipment with a price very similar to the ammonia mechanical compression equipment. The equipment consists of five main heat exchangers and a solution pump, resulting in a high reliability of its operation, requiring a minimum maintenance. The operation cost depends directly of the cost of the energy source. In case of using residual heat the operation cost is only the maintenance cost. Nowadays the cost of the electric energy is below the production cost, which can be a short term situation. In time terms of the comparable useful life time of an absorption refrigeration system (in excess of 20 years), it is reasonable to think that the operation costs will be less than the operation costs of an equipment with mechanical compression. To this day it is available a demonstration unit to exhibit the system in industrial plants with different energy sources. [Espanol] La refrigeracion por absorcion amoniaco/nitrato de litio ofrece grandes ventajas comparada tanto con la refrigeracion por compresion mecanica con amoniaco como con la refrigeracion por absorcion amoniaco/agua. Este sistema es mas eficiente y sencillo que el sistema de amoniaco/agua. Con calor de temperatura (100 a 140 grados centigrados por ejemplo vapor de baja presion, se permite la generacion de frio a temperaturas bajas (-10 a -20 grados centigrados). El sistema tiene menos componentes y es mucho mas barato que equipo de amoniaco/agua con un precio muy similar a sistemas por compresion mecanica de amoniaco. El sistema consiste en cinco

  18. Computer Based Thermodynamic Properties of Ammonia-Water Mixture for the Analysis of Power and Refrigeration Cycles

    Kausik Sadhukhan

    2012-06-01

    Full Text Available The thermodynamic analysis and optimization of combined power and refrigeration cycle as well as the improved vapour absorption refrigeration system necessitate the development of computer based thermodynamic properties of ammonia-water mixture. In this work, a computer code has been developed for the thermodynamic properties of ammonia water mixture for different pressures, temperatures and ammonia mass fraction concentration. This has been achieved by using some exact thermodynamic relations and some co-relations available in the literature. The computed results have been compared with the published experimental data and the agreement is found to be of good accuracy. The errors in the computed results for different thermodynamic properties are slightly more at comparatively high pressure and temperature. The maximum error is found to be with saturated liquid mixture entropy and its value is also less then 3.8% even at a high pressure of 34.47 bar.

  19. Parametric optimum analysis of an irreversible Ericsson cryogenic refrigeration cycle working with an ideal Fermi gas

    Bihong Lin; Yingru Zhao; Jincan Chen

    2008-05-01

    An irreversible model of an Ericsson cryogenic refrigeration cycle working with an ideal Fermi gas is established, which is composed of two isothermal and two isobaric processes. The influence of both the quantum degeneracy and the finite-rate heat transfer between the working fluid and the heat reservoirs on the performance of the cycle is investigated, based on the theory of statistical mechanics and thermodynamic properties of an ideal Fermi gas. The inherent regeneration losses of the cycle are analyzed. Expressions for several important performance parameters such as the coefficient of performance, cooling rate and power input are derived. By using numerical solutions, the cooling rate of the cycle is optimized for a given power input. The maximum cooling rate and the corresponding parameters are calculated numerically. The optimal regions of the coefficient of performance and power input are determined. Especially, the optimal performance of the cycle in the strong and weak gas degeneracy cases and the high temperature limit is discussed in detail. The analytic expressions of some optimized parameters are derived. Some optimum criteria are given. The distinctions and connections between the Ericsson refrigeration cycles working with the Fermi and classical gases are revealed.

  20. Profit rate performance optimization for a generalized irreversible combined refrigeration cycle

    Kang Ma; Lingen Chen; Fengrui Sun

    2009-10-01

    Finite-time exergoeconomic performance of a Newtonian heat transfer law system generalized irreversible combined refrigeration cycle model with finite-rate heat transfer, heat leakage and internal irreversibility is presented in this paper. The operation of the generalized irreversible combined refrigeration cycle is viewed as a production process with exergy as its output. The performance optimization of the cycle is performed by taking profit as the objective. The optimal profit rate, optimal COP (coefficient of performance), as well as the relation between the optimal profit rate and COP of the cycle are derived. The focus of this paper is to obtain the compromise optimization between economics (profit rate) and the energy utilization factor (COP) for the cycle, by searching the optimum COP at maximum profit rate, which is termed as the finite time exergoeconomic performance bound. Moreover, the effects of various factors, including heat leakage, internal irreversibility and the price ratio, on the profit rate performance of the cycle are analysed by detailed numerical examples.

  1. First Law Analysis of a Two-stage Ejector-vapor Compression Refrigeration Cycle working with R404A

    Feiza Memet

    2011-10-01

    Full Text Available The traditional two-stage vapor compression refrigeration cycle might be replaced by a two-stage ejector-vapor compression refrigeration cycle if it is aimed the decrease of irreversibility during expansion. In this respect, the expansion valve is changed with an ejector. The performance improvement is searched in the case of choosing R404A as a refrigerant. Using the ejector as an expansion device ensures a higher value for COP compared to the traditional case. On the basis of the ejector approach it possible to identify the highest COP value for a given condensation temperature, when the evaporation temperature varies.

  2. Performance optimization of quantum Brayton refrigeration cycle working with spin systems

    The new model of a quantum refrigeration cycle composed of two adiabatic and two isomagnetic field processes is established. The working substance in the cycle consists of many non-interacting spin-1/2 systems. The performance of the cycle is investigated, based on the quantum master equation and semi-group approach. The general expressions of several important performance parameters, such as the coefficient of performance, cooling rate and power input, are given. It is found that the coefficient of performance of this cycle is a close analogue of the classical Carnot-cycle. Some performance characteristic curves relating the cooling rate, the coefficient of performance and power input are plotted. Further, for high temperatures, the optimal relations between the cooling rate and the coefficient of performance are analyzed in detail

  3. The optimal performance of a quantum refrigeration cycle working with harmonic oscillators

    Lin Bi Hong; Hua Ben

    2003-01-01

    The cycle model of a quantum refrigeration cycle working with many non-interacting harmonic oscillators and consisting of two isothermal and two constant-frequency processes is established. Based on the quantum master equation and semi-group approach, the general performance of the cycle is investigated. Expressions for some important performance parameters, such as the coefficient of performance, cooling rate, power input, and rate of the entropy production, are derived. Several interesting cases are discussed and, especially, the optimal performance of the cycle at high temperatures is discussed in detail. Some important characteristic curves of the cycle, such as the cooling rate versus coefficient of performance curves, the power input versus coefficient of performance curves, the cooling rate versus power input curves, and so on, are presented. The maximum cooling rate and the corresponding coefficient of performance are calculated. Other optimal performances are also analysed. The results obtained here ...

  4. Performance Analysis of Solar Combined Ejector-Vapor Compression Cycle Using Environmental Friendly Refrigerants

    A. B. Kasaeian

    2013-04-01

    Full Text Available In this study, a new model of a solar combined ejector-vapor compression refrigeration system has been considered. The system is equipped with an internal heat exchanger to enhance the performance of the cycle. The effects of working fluid and operating conditions on the system performance including COP, entrainment ratio (ω, compression ratio (rp and exergy efficiency were investigated. Some working fluids suggested are: R114, R141b, R123, R245fa, R600a, R365mfc, R1234ze(e and R1234ze(z. The results show that R114 and R1234ze(e yield the highest COP and exergy efficiency followed by R123, R245fa, R365mfc, R141b, R152a and R600a. It is noticed that the COP value of the new solar ejector-vapor compression refrigeration cycle is higher than that of the conventional ejector cycle with R1234ze(e for all operating conditions. This paper also demonstrates that R1234ze(e will be a suitable refrigerant in the solar combined ejector-vapor compression refrigeration system, due to its environmental friendly properties and better performance. ABSTRAK: Kajian ini menganalisa model baru sistem penyejukan mampatan gabungan ejektor-wap solar.Sistem ini dilengkapi dengan penukar haba dalaman untuk meningkatkan prestasi kitaran.Kesan bendalir bekerja dan keadaan operasi pada prestasi sistem termasuk COP, nisbah pemerangkapan (ω, nisbah mampatan (rp dan kecekapan eksergi telah disiasat.Beberapa bendalir bekerja yang dicadangkan adalah: R114, R141b, R123, R245fa, R600a, R365mfc, R1234ze(e dan R1234ze(z.Hasil kajian menunjukkan R114 dan R1234ze(e menghasilkan COP dan kecekapan eksergi tertinggi diikuti oleh R123, R245fa, R365mfc, R141b, R152a dan R600a.Didapati nilai COP kitaran penyejukan mampatan bagi ejektor-wap solar baru adalah lebih tinggi daripada kitaran ejektor konvensional dengan R1234ze(e bagi semua keadaan operasi.Kertas kerja ini juga menunjukkan bahawa R1234ze(e boleh menjadi penyejuk yang sesuai dalam sistem penyejukan mampatan gabungan ejektor

  5. An analysis of the performance of an ejector refrigeration cycle working with R134a

    Memet, F.; Preda, A.

    2015-11-01

    In the context of recent developments in the field of energy, the aspect related to energy consumption is of great importance for specialists. Many industries rely on refrigeration technologies, a great challenge being expressed by attempts in energy savings in this sector. In this respect, efforts oriented towards efficient industrial refrigeration systems have revealed the necessity of a proper design. The most commonly used method of cooling is based on vapor compression cycles. Compared to vapor compression refrigeration systems, an ejector refrigeration system shows an inferior performance, indicated by the Coefficient of Performance of the cycle, but it is more attractive from energy saving point of view. In this respect, the present study deals with a theoretically analysis of an Ejector Refrigeration System, started with the presentation of the typical ejector design. It is stated that ejector refrigeration is a thermally driven system which requires low grade thermal energy for its working. After a short description of the analyzed system, are given equations for thermal loads and Coefficient of Performance calculation, on First Law basis. The working fluid considered in this research is Freon R134a. The developed study is focused on the effect of generating temperature variation on the Coefficient of Performance (COP) and on the work input to the pump when the cooling effect, the condensation temperature, the evaporation temperature and the reference state temperature are kept constant. Are obtained results in the following conditions: the condensation temperature is tc = 33°C, the evaporation temperature is te = 3°C, the reference state temperature is to = 23°C. The generating temperature varies in the range 82 ÷ 92°C and the cooling effect is 1 kW. Also, are known the isentropic efficiencies of the ejector, which are 0.90, and the isentropic efficiency of the pump, which is 0.75. Calculation will reveal that the Coefficient of Performance is

  6. Analysis of Decentralized Control for Absorption Cycle Heat Pumps

    Vinther, Kasper; Just Nielsen, Rene; Nielsen, Kirsten Mølgaard; Andersen, Palle; Pedersen, Tom Søndergård; Bendtsen, Jan Dimon

    Email Print Request Permissions This paper investigates decentralized control structures for absorption cycle heat pumps and a dynamic nonlinear model of a single-effect LiBr-water absorption system is used as case study. The model has four controllable inputs, which can be used to stabilize the...

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

    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 (COPT) 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 COPT 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

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

    Zhenying Zhang

    2014-08-01

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

  9. Integrated vacuum absorption steam cycle gas separation

    Chen, Shiaguo; Lu, Yonggi; Rostam-Abadi, Massoud

    2011-11-22

    Methods and systems for separating a targeted gas from a gas stream emitted from a power plant. The gas stream is brought into contact with an absorption solution to preferentially absorb the targeted gas to be separated from the gas stream so that an absorbed gas is present within the absorption solution. This provides a gas-rich solution, which is introduced into a stripper. Low pressure exhaust steam from a low pressure steam turbine of the power plant is injected into the stripper with the gas-rich solution. The absorbed gas from the gas-rich solution is stripped in the stripper using the injected low pressure steam to provide a gas stream containing the targeted gas. The stripper is at or near vacuum. Water vapor in a gas stream from the stripper is condensed in a condenser operating at a pressure lower than the stripper to concentrate the targeted gas. Condensed water is separated from the concentrated targeted gas.

  10. Performance optimization of a two-circuit cycle with parallel evaporators for a domestic refrigerator-freezer

    Yoon, Won Jae; Jung, Hae Won; Chung, Hyun Joon; Kim, Yongchan [Department of Mechanical Engineering, Korea University, Anam-Dong, Sungbuk-Ku, Seoul 136-713 (Korea, Republic of)

    2011-01-15

    A two-circuit cycle with parallel evaporators (called a ''parallel cycle'') for a domestic refrigerator-freezer (RF) shows energy saving potential compared with a conventional cycle with a single loop or serial evaporators because of a low compression ratio in the fresh food compartment (R)-operation. The objective of this study is to investigate the effects of the refrigerant charge, R-capillary tube, and refrigerant recovery operation on the performance of a parallel cycle. In addition, design guidelines for the heat transfer area and air flow rate of an R-evaporator are proposed. When the parallel cycle was optimized in terms of the refrigerant charge and R-capillary tube diameter, the energy consumption was reduced by 7.8% over a bypass two-circuit cycle with the same RF platform. In addition, an additional energy saving of 1.8% was obtained by the optimization of the operating sequence and refrigerant recovery operation. (author)

  11. Small-scale hydrogen liquefaction with a two-stage Gifford-McMahon cycle refrigerator

    Nakano, Akihiro; Maeda, Tetsuhiko; Ito, Hiroshi [National Institute of Advanced Industrial Science and Technology, Energy Technology Research Institute, 1-2-1 Namiki, Tsukuba East, Tsukuba, Ibaraki 305-8564 (Japan); Masuda, Masao; Kawakami, Yoshiaki; Kato, Atsushi [Takasago Thermal Engineering Co., Ltd., Research and Development Center, 3150 Iiyama Atsugi City, Kanagawa 243-0213 (Japan); Tange, Manabu [Shibaura Institute of Technology, Department of Mechanical Engineering, 3-7-5 Toyosu Koto-ku, Tokyo 135-8548 (Japan); Takahashi, Toru [University of Tsukuba, Department of Engineering Mechanics and Energy, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Matsuo, Masahiro [JECC Torisha Co., Ltd., 2-8-52 Yoshinodai, Kawagoe, Saitama 350-0833 (Japan)

    2010-09-15

    We manufactured a small-scale hydrogen liquefier with a two-stage 10 K Gifford-McMahon cycle (GM) refrigerator. It had a hydrogen tank with the volume of 30 L that was surrounded by a radiation shield. This liquefier continuously liquefied gaseous hydrogen with the volumetric flow rate of 12.1 NL/min. It corresponds to the liquefaction rate of 19.9 L/day for liquid hydrogen. We proposed a simple estimation method for the liquefaction rate and confirmed that the estimation method well explained the experimental result. To evaluate the estimation method, we applied the estimation method to other liquefiers. In case of a liquefier with the GM refrigerator, we confirmed the estimation method was available for predicting the liquefaction rate. However, in case of a liquefier with the pulse tube refrigerator, the results of the estimation indicated small values as compared with the experimental data. We discuss the details about the estimation method of the liquefaction rate for the small-scale liquefiers. (author)

  12. Effect of an Internal Heat Exchanger on Performance of the Transcritical Carbon Dioxide Refrigeration Cycle with an Expander

    Zhenying Zhang

    2014-11-01

    Full Text Available The effect of the internal heat exchanger (IHE on the performance of the transcritical carbon dioxide refrigeration cycle with an expander is analyzed theoretically on the basis of the first and second laws of thermodynamics. The possible parameters affecting system efficiency such as heat rejection pressure, gas cooler outlet temperature, evaporating temperature, expander isentropic efficiency and IHE effectiveness are investigated. It is found that the IHE addition in the carbon dioxide refrigeration cycle with an expander increases the specific cooling capacity and compression work, and decreases the optimum heat rejection pressure and the expander output power. An IHE addition does not always improve the system performance in the refrigeration cycle with an expander. The throttle valve cycle with IHE provides a 5.6% to 17% increase in maximum COP compared to that of the basic cycle. For the ideal expander cycle with IHE, the maximum COP is approximately 12.3% to 16.1% lower than the maximum COP of the cycle without IHE. Whether the energy efficiency of the cycle by IHE can be improved depends on the isentropic efficiency level of the expander. The use of IHE is only applicable in the cases of lower expander isentropic efficiencies or higher gas cooler exit temperatures for the refrigeration cycle with an expander from the view of energy efficiency.

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

    In this paper, a modified dual-evaporator CO2 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 CO2 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 CO2 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

  14. Application of Absorption Refrigeration in the Coal Mine & Fluent Simulation%吸收式制冷在深部矿井高温热害处理中的应用与FLUENT模拟计算

    杨前明; 杜雪

    2015-01-01

    For mine deep heat damage problem, effective use of low-grade waste heat of the Swallet, as the driving heat absorption refrigeration constructed absorption refrigeration, resolve deep coal thermal damage circulatory system through the use of deep water source heat pump heated gushing, so lithium bromide absorption chiller cooling at the same time on the working surface, as the heat absorption refrigeration cycle using design using auxiliary heating source heat pump to drive the refrigeration unit Swallet system. Fluent use of numerical simulation of the text, comparative analysis of the effect of coal mine deep under the best air cooling conditions, to provide a theoretical basis for the absorption refrigeration technology in actual use in deep.%针对煤矿深部热害问题,提出了利用矿井涌水中的低品位废热,作为吸收式制冷的驱动热源,构建了吸收式制冷循环系统解决煤矿深部开采工作面热害问题。依据煤矿深井开采工作面热舒适度要求,对制冷降温系统热参数进行估算;运用Fluent数值模拟,对比分析出最佳送风条件下的煤矿深井制冷效果。理论分析与数值模拟结果表明了采用吸收式制冷循环解决煤矿深井开采工作面热害问题可行性。

  15. Absorption heat cycles. An experimental and theoretical study

    A flow sheeting programme, SHPUMP, was developed for simulating different absorption heat cycles. The programme consists of ten different modules which allow the user to construct his own absorption cycle. The ten modules configurate evaporators, absorbers, generators, rectifiers, condensers, solution heat exchangers, pumps, valves, mixers and splitters. Seven basic and well established absorption cycles are available in the configuration data base of the programme. A new Carnot model is proposed heat cycles. Together with exergy analysis, general equations for the Carnot coefficient of performance and equations for thermodynamic efficiency, exergetic efficiency and exergy index, are derived, discussed and compared for both absorption heat pumps and absorption heat transformers. Utilizing SHPUMP, simulation results are presented for different configurations where absorption heat cycles are suggested to be incorporated in three different unit operations within both pulp and paper and oleochemical industries. One of the application studies reveled that an absorption heat transformer incorporated with an evaporation plant in a major pulp and paper industry, would save 18% of the total prime energy consumption in one of the evaporation plants. It was also concluded that installing an absorption heat pump in a paper drying plant would result in steam savings equivalent to 12 MW. An experimental absorption heat transformer unit operating with self-circulation has been modified and thoroughly tested. A reference heat transformer plant has been designed and installed in a major pulp and paper mill where it is directly incorporated with one of the evaporation plants. Preliminary plant operation data are presented. 72 refs, 63 figs, 33 tabs

  16. Study of a magnetic refrigeration cycle by active regeneration between 15 and 4.2 kelvins

    Magnetic refrigeration with active regeneration cycles was realized on a test bench. From a hot source at 14K cold power near 20 mW is reached on liquid helium at 4.2 K. Efficiency of the cooling loop is around 0.20. Different geometries are tested and a part of observed physical phenomena are simulated with a numerical model. Interest of ferromagnetic cryogenic materials for the range 4-15 K is evidenced by measurement of thermomagnetic properties of europium sulfide

  17. Performance Analysis of Solar Combined Ejector-Vapor Compression Cycle Using Environmental Friendly Refrigerants

    A. B. Kasaeian; S. Daviran

    2013-01-01

    In this study, a new model of a solar combined ejector-vapor compression refrigeration system has been considered. The system is equipped with an internal heat exchanger to enhance the performance of the cycle. The effects of working fluid and operating conditions on the system performance including COP, entrainment ratio (ω), compression ratio (rp) and exergy efficiency were investigated. Some working fluids suggested are: R114, R141b, R123, R245fa, R600a, R365mfc, R1234ze(e) and R1234ze(z)....

  18. Proceedings of the 1993 non-fluorocarbon insulation, refrigeration and air conditioning technology workshop

    1994-09-01

    Sessions included: HFC blown polyurethanes, carbon dioxide blown foam and extruded polystyrenes, plastic foam insulations, evacuated panel insulation, refrigeration and air conditioning, absorption and adsorption and stirling cycle refrigeration, innovative cooling technologies, and natural refrigerants. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.

  19. Some comments about the comparison between a conventional and a solar powered absorption refrigeration system

    Two statements about the performance of solar refrigeration systems are discussed. First, concepts of efficiency and coefficient of performance are studied. Second, the influence of inflation and rise of fuel prices are considered, in relation to the comparison between solar and conventional refrigeration systems. (author)

  20. Multi-objective optimization of an irreversible Stirling cryogenic refrigerator cycle

    Highlights: • A parametric investigation of irreversible Stirling cryogenic refrigerator cycles is presented. • Both internal and external irreversibilities are included in this study, moreover, heat capacities of external reservoirs are involved. • Multi-objective evolutionary algorithm based on NSGA-II approach is utilized. • Three robust decision making approaches are utilized to determine final optimum solution. - Abstract: The main aim of this research article is a parametric demonstration of irreversible Stirling cryogenic refrigerator cycles that includes irreversibilities such as external and internal irreversibilities. In addition, through this study, finite heat capacities of external reservoirs are considered accordingly. To reach the addressed goal of this research, three objective functions that include the input power of the Stirling refrigerator, the coefficient of performance (COP) and cooling load (RL) have been involved in optimization process simultaneously. The first aforementioned objective function has to minimize; the rest objective functions, on the other hand, have to maximize in parallel optimization process. Developed multi objective evolutionary approaches (MOEAs) based on NSGA-II algorithm is implemented throughout this work. Moreover, cold-side’s effectiveness of the heat exchanger, hot-side’s effectiveness of the heat exchanger, heat source’s heat capacitance rate, heat sink’s capacitance rate, temperature ratio ((Th)/(Tc) ), temperature of cold side are assigned as decision variables for decision making procedure. To gain a robust decision, different decision making approaches that include TOPSIS, LINMAP and fuzzy Bellman–Zadeh are used. Pareto optimal frontier was determined precisely and then three final outputs have been gained by means of the mentioned decision making approaches

  1. Performance Analysis of a Double-effect Adsorption Refrigeration Cycle with a Silica Gel/Water Working Pair

    Marlinda, Marlinda; Uyun, Aep Saepul; Miyazaki, Takahiko; Ueda, Yuki; Akisawa, Atsushi

    2010-01-01

    A numerical investigation of the double-effect adsorption refrigeration cycle is examined in this manuscript. The proposed cycle is based on the cascading adsorption cycle, where condensation heat that is produced in the top cycle is utilized as the driving heat source for the bottom cycle. The results show that the double-effect cycle produces a higher coefficient of performance (COP) as compared to that of the conventional single-stage cycle for driving temperatures between 100 °C and 150 °...

  2. Performance Analysis of a Double-effect Adsorption Refrigeration Cycle with a Silica Gel/Water Working Pair

    Atsushi Akisawa; Takahiko Miyazaki; Yuki Ueda; Marlinda; Aep Saepul Uyun

    2010-01-01

    A numerical investigation of the double-effect adsorption refrigeration cycle is examined in this manuscript. The proposed cycle is based on the cascading adsorption cycle, where condensation heat that is produced in the top cycle is utilized as the driving heat source for the bottom cycle. The results show that the double-effect cycle produces a higher coefficient of performance (COP) as compared to that of the conventional single-stage cycle for driving temperatures between 100 °C and 150 ...

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

    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. Thermodynamic Investigation of Two-Stage Absorption Refrigeration System Connected by a Compressor

    L. Kairouani; E. Nehdi; R. B. Iffa

    2005-01-01

    The present work is to analyze a two-stage cycle based on the ammonia-water absorption system, with intermediate compression. The two generators of the system are heated by geothermal energy at low temperature. The study shows that this system makes it possible at lower generator temperature, under the limits permitted by the systems suggested up to now. For Tg = 335 K, Tc = Ta = 308 K and Te = 263 K, based on the electric consumption, the system efficiency is 8.2. The comparative study of th...

  5. Second Law of Thermodynamics Analysis of Transcritical Carbon Dioxide Refrigeration Cycle

    杨俊兰; 马一太; 管海清; 李敏霞

    2004-01-01

    In order to identify the locations of irreversible loss within the transcritical carbon dioxide refrigeration cycle with an expansion turbine, a method with respect to the second law of thermodynamics based on exergy analysis model is applied. The effects of heat rejection pressures, outlet temperatures of gas cooler and evaporating temperatures on the exergy loss, exergy efficiency and the coefficient of performance (COP) of the expansion turbine cycle are analyzed. It is found that the great percentages of exergy losses take place in the gas cooler and compressor. Moreover, heat rejection pressures, outlet temperatures of gas cooler and evaporating temperatures have strong influence on the exergy efficiency, COP and the exergy loss of each component. The analysis shows that there exists an optimal heat rejection pressure corresponding to the maximum exergy efficiency and COP, respectively. The results are of significance in providing theoretical basis for optimal design and the control of the transcritical carbon dioxide system with an expansion turbine.

  6. A first-principles simulation model for the start-up and cycling transients of household refrigerators

    Hermes, Christian J.L.; Melo, Claudio [POLO Research Laboratories for Emerging Technologies in Cooling and Thermophysics, Federal University of Santa Catarina, 88040-970 Florianopolis, SC (Brazil)

    2008-12-15

    A first-principles model for simulating the transient behavior of household refrigerators is presented in this study. The model was employed to simulate a typical frost-free 440-l top-mount refrigerator, in which the compressor is on-off controlled by the freezer temperature, while a thermo-mechanical damper is used to set the fresh-food compartment temperature. Innovative modeling approaches were introduced for each of the refrigerator components: heat exchangers (condenser and evaporator), non-adiabatic capillary tube, reciprocating compressor, and refrigerated compartments. Numerical predictions were compared to experimental data showing a reasonable level of agreement for the whole range of operating conditions, including the start-up and cycling regimes. The system energy consumption was found to be within {+-}10% agreement with the experimental data, while the air temperatures of the compartments were predicted with a maximum deviation of {+-}1 C. (author)

  7. Experimental research on a new solar pump-free lithium bromide absorption refrigeration system with a second generator

    Yaxiu, Gu; Yuyuan, Wu; Xin, Ke [Department of Refrigerating and Cryogenic Engineering, Xi' an Jiaotong University, Xi' an 710049 (China)

    2008-01-15

    This paper is concerned with experimental research on a new solar pump-free lithium bromide absorption refrigeration system with a second generator. By using the second generator together with a lunate thermosiphon elevation tube, the required minimum driving temperature of the heat source is only 68{sup o}C compared to above 100{sup o}C in traditional absorption refrigeration systems. Based on the horizontal-tube falling-film method, the performance of the absorber can be enhanced by the second generator due to an increase in the differential concentration of the solution between the inlet and the outlet of the absorber and an increase in the temperature difference between the inlet and the outlet of the cooling water in the absorber. The yield of condensate with the second generator open is increased by 68% compared to that with the second generator closed. The performance of the evaporator is significantly improved due to the increase in temperature drop of the chilled water and the decrease in the outlet temperature of the chilled water. This leads to an improvement of the performance of the overall refrigeration system. The maximum coefficient of performance (COP) approaches 0.787. (author)

  8. Effects caused by the internal heat exchanger at the low temperature cycle in a cascade refrigeration plant

    Llopis Doménech, Rodrigo; Sanz Kock, Carlos; Cabello López, Ramón; Sánchez García-Vacas, Daniel; Nebot-Andrés, Laura; Catalán-Gil, Jesús

    2016-01-01

    This work analyses and quantifies the effects caused by the use of an internal heat exchanger (IHX) at the CO2 subcritical cycle in an HFC134a/CO2 cascade refrigeration plant that incorporates a gas-cooler at the exit of the low temperature compressor. Previous theoretical and experimental studies showed that the IHX reduces the refrigeration capacity and COP of the subcritical cycle, however, it has been seen that it also lowers the heat to be rejected at the condenser. This redu...

  9. Comparative study of cycle modification strategies for trans-critical CO2 refrigeration cycle for warm climatic conditions

    Simarpreet Singh

    2016-03-01

    Full Text Available This paper presents a comparative study of performance of six prominent modifications on the basic trans-critical CO2 refrigeration system to investigate their suitability to high ambient temperature application (35–55 °C. To explore the application in chiller, domestic refrigeration and air cooling the evaporator temperature chosen are −10 °C, 0 °C and 10 °C respectively. In general the cycle modifications have a positive effect on the overall COP of the system. However, to comprehend practicability of these modifications for three application areas, a few other parameters which affect design and operation are also included in the study. These are compressor discharge pressure and temperature, mass flow rate, interstage pressure for multi-stage operation and exergy destruction. Effect of real time constraints like approach temperature, pressure drop in gas cooler, compressors efficieny, degree of superheat, expanders efficiency and effectivenesss of intermediate heat exchanger are also incorporated. Interrelation between these parameters are brought out from the study.

  10. Candidate chemical systems for air cooled, solar powered, absorption air conditioner design. Part II. Solid absorbents, high latent heat refrigerants

    Biermann, W. J.

    1978-04-01

    Work done in attempting to qualify absorption refrigeration systems based on refrigerants with intermediate latent heats of vaporization is summarized. In practice, these comprise methanol, ammonia, and methylamine. A wide variety of organic substances, salts, and mixtures were evaluated in as systematic a manner as possible. Several systems of interest are described. The system, LiClO/sub 3/--LiBr--H/sub 2/O, is a good back up system to our first choice of an antifreeze additive system, and thermodynamically promising but subject to some inconvenient materials limitations. The system, LiBr/ZnBr/sub 2/--methanol, is thermodynamically promising but requires additional kinetic qualification. Chemical stability of the system, LiCNS--ammonia/methylamine with various other third components, does not appear to be adequate for a long-lived system.

  11. Solar hybrid cooling system for high-tech offices in subtropical climate - Radiant cooling by absorption refrigeration and desiccant dehumidification

    Fong, K.F., E-mail: bssquare@cityu.edu.hk [Building Energy and Environmental Technology Research Unit, School of Energy and Environment and Division of Building Science and Technology, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong (China); Chow, T.T.; Lee, C.K.; Lin, Z.; Chan, L.S. [Building Energy and Environmental Technology Research Unit, School of Energy and Environment and Division of Building Science and Technology, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Kowloon, Hong Kong (China)

    2011-08-15

    Highlights: {yields} A solar hybrid cooling system is proposed for high-tech offices in subtropical climate. {yields} An integration of radiant cooling, absorption refrigeration and desiccant dehumidification. {yields} Year-round cooling and energy performances were evaluated through dynamic simulation. {yields} Its annual primary energy consumption was lower than conventional system up to 36.5%. {yields} The passive chilled beams were more energy-efficient than the active chilled beams. - Abstract: A solar hybrid cooling design is proposed for high cooling load demand in hot and humid climate. For the typical building cooling load, the system can handle the zone cooling load (mainly sensible) by radiant cooling with the chilled water from absorption refrigeration, while the ventilation load (largely latent) by desiccant dehumidification. This hybrid system utilizes solar energy for driving the absorption chiller and regenerating the desiccant wheel. Since a high chilled water temperature generated from the absorption chiller is not effective to handle the required latent load, desiccant dehumidification is therefore involved. It is an integration of radiant cooling, absorption refrigeration and desiccant dehumidification, which are powered up by solar energy. In this study, the application potential of the solar hybrid cooling system was evaluated for the high-tech offices in the subtropical climate through dynamic simulation. The high-tech offices are featured with relatively high internal sensible heat gains due to the intensive office electric equipment. The key performance indicators included the solar fraction and the primary energy consumption. Comparative study was also carried out for the solar hybrid cooling system using two common types of chilled ceilings, the passive chilled beams and active chilled beams. It was found that the solar hybrid cooling system was technically feasible for the applications of relatively higher cooling load demand. The annual

  12. Solar hybrid cooling system for high-tech offices in subtropical climate - Radiant cooling by absorption refrigeration and desiccant dehumidification

    Highlights: → A solar hybrid cooling system is proposed for high-tech offices in subtropical climate. → An integration of radiant cooling, absorption refrigeration and desiccant dehumidification. → Year-round cooling and energy performances were evaluated through dynamic simulation. → Its annual primary energy consumption was lower than conventional system up to 36.5%. → The passive chilled beams were more energy-efficient than the active chilled beams. - Abstract: A solar hybrid cooling design is proposed for high cooling load demand in hot and humid climate. For the typical building cooling load, the system can handle the zone cooling load (mainly sensible) by radiant cooling with the chilled water from absorption refrigeration, while the ventilation load (largely latent) by desiccant dehumidification. This hybrid system utilizes solar energy for driving the absorption chiller and regenerating the desiccant wheel. Since a high chilled water temperature generated from the absorption chiller is not effective to handle the required latent load, desiccant dehumidification is therefore involved. It is an integration of radiant cooling, absorption refrigeration and desiccant dehumidification, which are powered up by solar energy. In this study, the application potential of the solar hybrid cooling system was evaluated for the high-tech offices in the subtropical climate through dynamic simulation. The high-tech offices are featured with relatively high internal sensible heat gains due to the intensive office electric equipment. The key performance indicators included the solar fraction and the primary energy consumption. Comparative study was also carried out for the solar hybrid cooling system using two common types of chilled ceilings, the passive chilled beams and active chilled beams. It was found that the solar hybrid cooling system was technically feasible for the applications of relatively higher cooling load demand. The annual primary energy

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

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

  14. Alternative Refrigerants: A Review

    S.K. Kalla*; , J.A. Usmani

    2014-01-01

    During the last decade, substantial research activities have been undertaken regarding refrigeration cycles and systems with particular emphasis on the replacement of refrigerants like R134a by refrigerants like hydrocarbons which have negligible GWP (Global Warming Potential).Besides using eco-friendly refrigerants, thrust has been given upon devising methods to increase the efficiency of the refrigeration cycle/system, which will also contribute to reducing emission of GHG(G...

  15. Performance Analysis of a Double-effect Adsorption Refrigeration Cycle with a Silica Gel/Water Working Pair

    Atsushi Akisawa

    2010-10-01

    Full Text Available A numerical investigation of the double-effect adsorption refrigeration cycle is examined in this manuscript. The proposed cycle is based on the cascading adsorption cycle, where condensation heat that is produced in the top cycle is utilized as the driving heat source for the bottom cycle. The results show that the double-effect cycle produces a higher coefficient of performance (COP as compared to that of the conventional single-stage cycle for driving temperatures between 100 °C and 150 °C in which the average cycle chilled water temperature is fixed at 9 °C. Moreover, the COP of the double-effect cycle is more than twice that of the single-stage cycle when the temperature reaches 130 °C. It is also observed that the adsorbent mass ratio of the high temperature cycle (HTC to the low temperature cycle (LTC affects the performance of the double-effect adsorption refrigeration cycle.

  16. Research and application of CO2 refrigeration and heat pump cycle

    2009-01-01

    The environmental problem caused by refrigerant has become the focus all over the world.As the most typical natural refrigerant,CO2,of course,becomes the research focus.This paper introduces the development and application status of CO2 refrigeration and heat pump technology.The researches on CO2 refrigeration and heat pump,carried out by Thermal Energy Research Institute,Tianjin University,also are presented in this paper.

  17. Research and application of CO2 refrigeration and heat pump cycle

    TIAN Hua; YANG Zhao; LI MinXia; MA YiTai

    2009-01-01

    The environmental problem caused by refrigerant has become the focus all over the world. As the most typical natural refrigerant, CO2, of course, becomes the research focus. This paper introduces the develop-ment and application status of CO2 refrigeration and heat pump technology. The researches on CO2 refrig-eration and heat pump, carried out by Thermal Energy Research Institute, Tianjin University, also are pre-sented in this paper.

  18. Low-temperature measurement system based on a closed-cycle refrigerator

    We have built a new torque magnetometer with a closed-cycle helium refrigerator. The temperature can be lowered down to 1.5 K by pumping liquefied helium in sample space. The temperature can be stabilized within ±0.01 K by using the two-independent PID loops. A piezoresistor bridge configured with a silicon cantilever surface is used to detect a torque. A transeverse magnetic field, which is fabricated by the several pieces of the permanent magnets, can produce a field up to 10 kG in any direction. The system has complete control from a computer by coding a LabVIEW. We have demonstrated the torque curves of a single crystal YBa2Cu4O8 successfully even at 1.6 K

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

    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. Performance of Organic Rankine Cycle in Different Refrigerants for Low Temperature Geothermal using Delphi Program

    Prabowo .

    2010-01-01

    Full Text Available A software has been developed in a Windows-based Delphi programming for analyzing the influence of the transport and thermodynamic properties of the refrigerants on the performance of the Organic Rankine Cycle (ORC. Its user-friendly drag and drop icon format and excellent color graphics make it an interactive tool for teaching and the preliminary design of the ORC system. The research was carried out by analyzing the performance of the system components and the overall ORC based on the several working fluids within R22, R123, R134a and RC318. The pressure of evaporator was varied in two steps 7 and 12 bar, while the condenser was kept constant pressure at 1 bar. The turbine inlet temperature was varied in the range 100 0C to 140 0C where the various isentropic efficiency inputs were applied for pump and turbine. By increasing turbine inlet temperature, R22 has the highest turbine work output and cycle efficiency. Contrary, RC318 has the lowest cycle efficiency and decreases trend with enhancing in turbine inlet temperature. RC318 has low latent heat of vaporization thus vaporizes under relatively very low evaporator heat supply.

  1. Effect of Suction Nozzle Pressure Drop on the Performance of an Ejector-Expansion Transcritical CO2 Refrigeration Cycle

    Zhenying Zhang; Lili Tian

    2014-01-01

    The basic transcritical CO2 systems exhibit low energy efficiency due to their large throttling loss. Replacing the throttle valve with an ejector is an effective measure for recovering some of the energy lost in the expansion process. In this paper, a thermodynamic model of the ejector-expansion transcritical CO2 refrigeration cycle is developed. The effect of the suction nozzle pressure drop (SNPD) on the cycle performance is discussed. The results indicate that the SNPD has little impact o...

  2. Entransy analysis of irreversible Carnot-like heat engine and refrigeration cycles and the relationships among various thermodynamic parameters

    Highlights: • Entransy analysis was made for irreversible heat engine and refrigeration cycles. • Entransy dissipations were defined and determined. • Relations between entransy dissipation and other thermodynamic parameters were determined. - Abstract: Because of the energy needs of the world and the issues involved with global warming, analyzing and optimizing power cycles have increased in importance. In this paper, the concepts of entransy dissipation, entropy generation, power output, exergy output, energy, exergy efficiencies for irreversible heat engine cycles and entransy dissipation, entropy generation, power inputs, exergy input, entropy generation, COP and the exergy of efficiency for the irreversible refrigeration cycle are applied as a means of analyzing them. The results are obtained numerically, and the optimum or critical values are determined for a dimensionless temperature ratio and a dimensionless heat conductance ratio. Finally, recommendations on the design and range of operating conditions for the cycles are presented. Values of TC/TE (x), can be selected between 0.5 and 0.55 and values of kE/kC (y) in the range of 0.3–0.5 can be selected for high performance and low losses in a heat engine. Choosing values of TC/TE (x) and kC/kE (y) as low as possible for high performance, besides low thermodynamic losses (entropy generation and entransy dissipation) for the refrigeration cycle

  3. Influence of quantum degeneracy and regeneration on the performance of Bose-Stirling refrigeration-cycles operated in different temperature regions

    The Stirling refrigeration cycle using an ideal Bose-gas as the working substance is called the Bose-Stirling refrigeration cycle, which is different from other thermodynamic cycles such as the Carnot cycle, Ericsson cycle, Brayton cycle, Otto cycle, Diesel cycle and Atkinson cycle working with an ideal Bose gas and may be operated across the critical temperature of Bose-Einstein condensation of the Bose system. The performance of the cycle is investigated, based on the equation of state of an ideal Bose gas. The inherent regenerative losses of the cycle are considered and the coefficient of performance and the amount of refrigeration of the cycle are calculated. The results obtained here are compared with those derived from the classical Stirling refrigeration cycle, using an ideal gas as the working substance. The influence of quantum degeneracy and inherent regenerative losses on the performance of the Bose Stirling refrigeration cycle operated in different temperature regions is discussed in detail, and consequently, general performance characteristics of the cycle are revealed

  4. Performance analysis of 404a/508b Cascade Refrigeration cycle for low temperature

    DEVANSHU PYASI

    2011-08-01

    Full Text Available This paper presents analytical results of analyzing blends of Hfc refrigerants such as 404a and 508b in Cascade Refrigeration System. Refrigerant blend 508b is a low boiling refrigerant and advantageous in low stage of cascade refrigeration system whereas 404a is used in high stage of cascade refrigeration system because of its high boiling point which is suitable for high temperature circuit. The analysis includes three basic parameters as :Evaporator temperature(Te,Condenser temperature (Tc, and temperature difference in cascade condenser (Dt .These parameters are varied one by one up to a limited range keeping other parameters constant and theeffect of these parameters on system COP , exergetic efficiency, mass flow ratio etc is analyzed. Analysis results also give the optimum values of the evaporator, condenser and cascade condenser temperature.

  5. Numerical optimization of a transcritical CO2/propylene cascaded refrigeration-heat pump system with economizer in HT cycle

    Alok Manas Dubey; Suresh Kumar; Ghanshyam Das Agrawal

    2015-04-01

    Use of organic refrigerants such as Hydrochlorofluorocarbons and Chlorofluorocarbons have been criticized for their adverse impact on the Earth's protective ozone layer and for their significant global warming potential (GWP). CO2 has been receiving great concern as an alternative refrigerant. Cascade refrigeration systems employing CO2 are used for low temperature applications. Being a low critical temperature fluid CO2 transcritical cascade systems offer low COP for a given application. Parallel compression economization is one of the promising cycle modifications to improve the COP of transcritical CO2 cascaded systems. In this paper, transcritical CO2/propylene cascade system with parallel compression economization in the HT cycle has been analysed for cooling/heating applications. An enhancement in COP of 9% has been predicted. Thermodynamic analysis on R744-R1270 cascade refrigeration system has been performed to determine the optimal value of the various design parameters of the system. The design parameters included are: gas cooler outlet temperature and intermediate temperature in the high temperature circuit and evaporator temperature and temperature difference in the cascade condenser in the low temperature circuit.

  6. Energetic and Exergetic Analysis of an Ejector-Expansion Refrigeration Cycle Using the Working Fluid R32

    Zhenying Zhang; Lirui Tong; Li Chang; Yanhua Chen; Xingguo Wang

    2015-01-01

    The performance characteristics of an ejector-expansion refrigeration cycle (EEC) using R32 have been investigated in comparison with that using R134a. The coefficient of performance (COP), the exergy destruction, the exergy efficiency and the suction nozzle pressure drop (SNPD) are discussed. The results show that the application of an ejector instead of a throttle valve in R32 cycle decreases the cycle’s total exergy destruction by 8.84%–15.84% in comparison with the basic cycle (BC). The R...

  7. Experimental evaluation of an internal heat exchanger in a CO2 subcritical refrigeration cycle with gas-cooler

    We present the experimental evaluation of an internal heat exchanger or suction-line/liquid-line heat exchanger in a CO2 subcritical refrigeration plant with gas-cooler. The plant, driven by a 1.5 kW CO2 semi hermetic compressor, uses brazed plate heat exchangers as condenser, evaporator and internal heat exchanger, an air finned tube gas-cooler and an electronic expansion valves. The evaluation (77 steady-states) covers evaporating temperatures from −40 to −25 °C and condensing temperatures from −15 to 0 °C, always at the nominal speed of the compressor. Here, the effect of the internal heat exchanger on the main energy parameters is analysed, i.e., cooling capacity, COP and heat rejection at gas-cooler and condenser. Also, the effect of the internal heat exchanger in a cascade cycle is analysed theoretically. It has been concluded that the internal heat exchanger does not improve the performance of the subcritical cycle, but it could improve the energy performance if it is used inside a cascade refrigeration system. - Highlights: • An internal heat exchanger in a CO2 subcritical refrigeration cycle is evaluated. • Evaluation range covered evaporating temperatures from −40 to −25 °C. • The IHX generally reduces the capacity and COP of the subcritical cycle. • In combination with a gas-cooler it reduces the heat rejection at the condenser. • Its effect on a cascade refrigeration cycle is positive

  8. Conceptual Design of Nuclear CCHP Using Absorption Cycle

    This paper aims at providing a conceptual idea on the combined cooling, heating and power (CCHP) using an absorption cycle to simultaneously generate both electricity and useful energy to be transferred, which is applicable to conventional or future water cooled reactors. The motivation of this paper is, as the number and the share of nuclear power plants (NPPs) increases, the necessity of a partial load operation will be increased in the case of South Korea. This means the surplus of nuclear energy. It should be better to find a method to fully use the burnup of nuclear fuels loaded once instead of cutting back reactor power. If the surplus energy from NPPs is not useable on-site, that should be transferred to a place such that the efficiency of an overall energy system can be maximized. The proposed solution is to use an absorption cycle which is connected to the Rankine cycle, a turbine side of water cooled reactors, so that the operation strategy of the nuclear steam supply system (NSSS) does not need to be changed. This principle can design a heat transfer mechanism to convey thermal energy to a long range, which means the waste heat discharged can be used for practical purposes even in a populated district. District heating/cooling, industrial process heat supply, or seawater desalination are expected to be the possible applications. This paper presents simulation results for deciding thermo-dynamic viability and economic feasibility by comparing several design alternatives. (author)

  9. Effect of Internal Heat Recovery in Ammonia-Water Absorption Cooling Cycles: Exergy and Structural Analysis

    Miquel Nogués

    2009-03-01

    Full Text Available First and second law analysis have been conducted for three low temperature driven ammonia-water absorption cooling cycles with increasing internal heat recovery. Based on the results of exergy analysis the structural analysis has been achieved. The obtained Coefficients of Structural Bonds (CSB consider how the irreversibility of the whole cycle is affected by a change in the irreversibility related to an efficiency improvement of a single component. Trends for the different configurations are similar, while quantitative differences among the main heat exchangers are considerable. The highest values of the CSB are found for the refrigerant heat exchanger. Also the evaporator, the condenser, the generator and the absorber show values higher than unity. The lowest CSB’s are obtained in the solution heat exchanger. In general, CSB’s decrease with increasing efficiency. That means that for very efficient heat exchangers, a further improvement looks less attractive. The dephlegmator is an exception as it shows a singularity of the CSB value due to its complex interactions with the other components. Once the CSB’s are obtained for the main components, they can be used in the structural method of the thermoeconomic optimisation. This method enables us to find the optimum design of a component in a straightforward calculation.

  10. Effect of an Internal Heat Exchanger on Performance of the Transcritical Carbon Dioxide Refrigeration Cycle with an Expander

    Zhenying Zhang; Lili Tian; Yanhua Chen; Lirui Tong

    2014-01-01

    The effect of the internal heat exchanger (IHE) on the performance of the transcritical carbon dioxide refrigeration cycle with an expander is analyzed theoretically on the basis of the first and second laws of thermodynamics. The possible parameters affecting system efficiency such as heat rejection pressure, gas cooler outlet temperature, evaporating temperature, expander isentropic efficiency and IHE effectiveness are investigated. It is found that the IHE addition in the carbon dioxide re...

  11. Absorption Cycle Heat Pump Model for Control Design

    Vinther, Kasper; Just Nielsen, Rene; Nielsen, Kirsten Mølgaard;

    2015-01-01

    actual heat pump located at a larger district heating plant. The model is implemented in Modelica and is based on energy and mass balances, together with thermodynamic property functions for LiBr and water and staggered grid representations for heat exchangers. Model parameters have been fitted to......Heat pumps have recently received increasing interest due to green energy initiatives and increasing energy prices. In this paper, a nonlinear dynamic model of a single-effect LiBr-water absorption cycle heat pump is derived for simulation and control design purposes. The model is based on an...

  12. Thermoeconomic Analysis of a Single and Double-Effect LiBr/H2O Absorption Refrigeration System

    Silvia Azucena Nebra

    2009-06-01

    Full Text Available

    The aim of this work is to carry out a thermoeconomic analysis of a single and double-effect LiBr/H2O absorption refrigeration system. The methodology of functional analysis with negentropy is used. The exergetic cost of the main product, the cooling cost, was calculated as a function of the exergy of the heat source. Two cases were analyzed for each system: the first considers a direct-fired system while the second considers a hot-water driven system for the single-effect system and a steam-driven system for the double effect system as part of a cogeneration system. As expected, the resultant exergetic cost of the main product was higher for the direct-fired system.

    • This paper is an updated version of a paper published in the ECOS'08 proceedings. 

  13. Exergoeconomic analysis and multi-objective optimization of an ejector refrigeration cycle powered by an internal combustion (HCCI) engine

    Highlights: • Ejector refrigeration systems powered by HCCI engine is proposed. • A new two-dimensional model is developed for the ejector. • Multi-objective optimization is performed for the proposed system. • Pareto frontier is plotted for multi-objective optimization. - Abstract: Ejector refrigeration systems powered by low-grade heat sources have been an attractive research subject for a lot of researchers. In the present work the waste heat from exhaust gases of a HCCI (homogeneous charge compression ignition) engine is utilized to drive the ejector refrigeration system. Considering the frictional effects on the ejector wall, a new two-dimensional model is developed for the ejector. Energy, exergy and exergoeconomic analysis performed for the proposed system using the MATLAB software. In addition, considering the exergy efficiency and the product unit cost of the system as objective functions, a multi-objective optimization is performed for the system to find the optimum design variables including the generator, condenser and evaporator temperatures. The product unit cost is minimized while the exergy efficiency is maximized using the genetic algorithm. The optimization results are obtained as a set of optimal points and the Pareto frontier is plotted for multi-objective optimization. The results of the optimization show that ejector refrigeration cycle is operating at optimum state based on exergy efficiency and product unit cost when generator, condenser and evaporator work at 94.54 °C, 33.44 °C and 0.03 °C, respectively

  14. Solar-driven refrigeration systems with focus on the ejector cycle

    Pridasawas, Wimolsiri

    2006-01-01

    Interest in utilizing solar-driven refrigeration systems for air-conditioning or refrigeration purposes has grown continuously. Solar cooling is com-prised of many attractive features and is one path towards a more sus-tainable energy system. Compared to solar heating, the cooling load, par-ticularly for air-conditioning applications, is generally in phase with solar radiation. The objective of this thesis is to establish a fundamental basis for further research and development within the fie...

  15. Experimental study of an ammonia-water bubble absorber using a plate heat exchanger for absorption refrigeration machines

    The development of absorption chillers activated by renewable heat sources has increased due mainly to the increase in primary energy consumption that causes problems such as greenhouse gases and air pollution among others. These machines, which could be a good substitute for compression systems, could be used in the residential and food sectors which require a great variety of refrigeration conditions. Nevertheless, the low efficiency of these machines makes it necessary to enhance heat and mass transfer processes in the critical components, mainly the absorber, in order to reduce their large size. This study used ammonia-water as the working fluid to look at how absorption takes place in a plate heat exchanger operating under typical conditions of absorption chillers, driven by low temperature heat sources. Experiments were carried out using a corrugated plate heat exchanger model NB51, with three channels, where ammonia vapor was injected in bubble mode into the solution in the central channel. The results achieved for the absorption flux were in the range of 0.0025-0.0063 kg m-2 s-1, the solution heat transfer coefficient varied between 2.7 and 5.4 kW m-2 K-1, the absorber thermal load from 0.5 to 1.3 kW. In addition, the effect of the absorber operating conditions on the most significant efficiency parameters was analyzed. The increase in pressure, solution and cooling flow rates positively affect the absorber performance, on the other hand an increase in the concentration, cooling, and solution temperature negatively affects the absorber performance

  16. Simple uniaxial pressure device for ac-susceptibility measurements suitable for closed cycle refrigerator system.

    Arumugam, S; Manivannan, N; Murugeswari, A

    2007-06-01

    A simple design of the uniaxial pressure device for the measurement of ac-susceptibility at low temperatures using closed cycle refrigerator system is presented for the first time. This device consists of disc micrometer, spring holder attachment, uniaxial pressure cell, and the ac-susceptibility coil wound on stycast bobbin. It can work under pressure till 0.5 GPa and at the temperature range of 30-300 K. The performance of the system at ambient pressure is tested and calibrated with standard paramagnetic salts [Gd(2)O(3), Er(2)O(3), and Fe(NH(4)SO(4))(2)6H(2)O], Fe(3)O(4), Gd metal, Dy metal, superconductor (YBa(2)Cu(3)O(7)), manganite (La(1.85)Ba(0.15)MnO(3)), and spin glass material (Pr(0.8)Sr(0.2)MnO(3)). The performance of the uniaxial pressure device is demonstrated by investigating the uniaxial pressure dependence of La(1.85)Ba(0.15)MnO(3) single crystal with P||c axis. The Curie temperature (T(c)) decreases as a function of pressure with P||c axis (dT(c)dP(||c axis)=-11.65 KGPa) up to 46 MPa. The design is simple, is user friendly, and does not require pressure calibration. Measurement can even be made on thin and small size oriented crystals. The failure of the coil is remote under uniaxial pressure. The present setup can be used as a multipurpose uniaxial pressure device for the measurement of Hall effect and thermoelectric power with a small modification in the pressure cell. PMID:17614625

  17. Two-phase flow modelling of a solar concentrator applied as ammonia vapor generator in an absorption refrigerator

    Ortega, N. [Posgrado en Ingenieria (Energia), Universidad Nacional Autonoma de Mexico, Privada Xochicalco s/n, Temixco, Morelos 62580 (Mexico); Garcia-Valladares, O.; Best, R.; Gomez, V.H. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Privada Xochicalco s/n, Temixco, Morelos 62580 (Mexico)

    2008-09-15

    A detailed one-dimensional numerical model describing the heat and fluid-dynamic behavior inside a compound parabolic concentrator (CPC) used as an ammonia vapor generator has been developed. The governing equations (continuity, momentum, and energy) inside the CPC absorber tube, together with the energy equation in the tube wall and the thermal analysis in the solar concentrator were solved. The computational method developed is useful for the solar vapor generator design applied to absorption cooling systems. The effect on the outlet temperature and vapor quality of a range of CPC design parameters was analyzed. These parameters were the acceptance half-angle and CPC length, the diameter and coating of the absorber tube, and the manufacture materials of the cover, the reflector, and the absorber tube. It was found that the most important design parameters in order to obtain a higher ammonia-water vapor production are, in order of priority: the reflector material, the absorber tube diameter, the selective surface, and the acceptance half-angle. The direct ammonia-water vapor generation resulting from a 35 m long CPC was coupled to an absorption refrigeration system model in order to determine the solar fraction, cooling capacity, coefficient of performance, and overall efficiency during a typical day of operation. The results show that approximately 3.8 kW of cooling at -10{sup o}C could be produced with solar and overall efficiencies up to 46.3% and 21.2%, respectively. (author)

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

    S. Anand

    2016-12-01

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

  19. Development of a directly solar driven refrigerator on the basis of a diffusion-absorption refrigeration process; Entwicklung einer direkt solar angetriebenen Kaelteanlage auf Basis des Diffusions-Absorptions-Kaelteprozesses

    Schmid, Fabian; Zetzsche, Marco; Spindler, Klaus [Stuttgart Univ. (DE). Inst. fuer Thermodynamik und Waermetechnik (ITW)

    2011-07-01

    In the past, the focus of solar cooling was on adsorption and absorption with capacities over 10 kW. A new concept for decentral solar cooling is currently under development at the Institute of Thermodynamics and Thermal Engineering. The concept is based on the diffusion-absorption refrigeration process, with solvent circulation based on the thermosyphon principle. The new system is free of wear, consumes no electricity and makes no noise. The components are partly integrated in the solar collector. A thermal capacity of about 400 W is intended. For higher capacites, several plants can be interconnected into a modular system. With a meander integrated in the soalr collector, the solar collector can also be used for water heating of necessary. Laboratory measurements included the influence of different heating capacities and the influence of recirculation cooling by free or forced convection on the refrigerating capacity of the system. The internal heat exchangers have great influence on capacity and performance; several variants were investigated and tested in practice. The cold generation process and the laboratory plant are described in detail, and performance results and measured values so far are presented. Future development steps and the potential of the technology are outlined. [German] In den letzten Jahren lag der Fokus der solaren Kuehlung auf Ad- und Absorptionskaelteanlagen. Diese Anlagen haben einen Leistungsbereich von mehr als 10 kW. Am Institut fuer Thermodynamik und Waermetechnik wird ein neues Konzept zur dezentralen solaren Kuehlung entwickelt. Grundlage ist der Diffusions-Absorptionskaelteprozess. Hierbei erfolgt der Loesungsmittelumlauf durch das Thermosiphonprinzip. Dadurch hat die entwickelte Anlage den Vorteil, dass sie verschleissfrei, strom- und geraeuschlos arbeitet. Die Bauteile der Kaelteanlage werden teilweise direkt in den Solarkollektor integriert (Thermosiphonpumpe/Austreiber). Es wird eine Kaelteleistung von circa 400 W angestrebt

  20. Entropy generation analysis of fan-supplied gas cooler within the framework of two-stage CO2 transcritical refrigeration cycle

    Highlights: ► Models for gas cooler and fan for CO2 refrigeration system was presented and validated. ► Effects of several design parameters were investigated within a refrigeration cycle. ► Both 1st law and 2nd law were employed for the analysis. - Abstract: Optimization design of heat exchangers based on entropy generation analysis is critical to improve the efficiency of CO2 refrigeration systems. However, most of the previous studies in this field were focused on individual components that are isolated from the entire system. Little has been done on the component analysis within the framework of entire refrigeration cycle. To probe this important issue, the entropy generation analysis is performed in this study on the fan-supplied gas cooler within a two-stage CO2 refrigeration system. The optimum circuit length is found by investigating the influences of geometrical parameters such as tube spacing, fin density and tube diameter on the heat transfer rate and entropy generation number of the gas cooler. The designed fan-coil is then put into the frame of the two-stage refrigeration cycle and its energy performance and exergy performance are both evaluated on the system level. The results show that the analysis with isolated gas cooler can lead to overestimated or unrealistic predictions on the heat transfer performance compared to the analysis within the framework of entire cycle.

  1. Study of thermodynamic properties of HFC refrigerant mixtures for Loretz-cycled niew generation air-conditioning equipment; Lorentz cycle ka shinsedai kucho kikiyo HFC kei kongo reibai no netsu rikigaku seishitsu ni kansuru kenkyu

    Watanabe, K.; Sato, H. [Keio University, Tokyo (Japan). Faculty of Science and Technology

    1997-02-01

    This paper describes thermodynamic properties of HFC refrigerant mixtures for Lorentz-cycled new generation air-conditioning equipment. Equipment has been completed for simultaneous measurement of density and vapor-liquid equilibrium property, accurate measurement of latent heat of vaporization, and accurate measurement of specific heat at constant pressure in liquid phase. Final adjustment and preliminary measurements are currently conducted. Through analytical investigation using actually measured data of thermodynamic properties of HFC refrigerant mixtures, five state equations were obtained, i.e., modified Peng-Robinson state equation which can reproduce the vapor-liquid equilibrium property of refrigerant mixtures, modified Patel-Teja state equation, Helmholtz function type state equation which is applicable in the whole fluid region of refrigerant mixtures, and so on. An evaluation test equipment has been fabricated as a trial for Lorentz-cycled air-conditioning equipments using HFC refrigerant mixtures, and demonstration test is conducted to confirm the validity. 9 refs., 5 figs.

  2. Performance investigation of a waste heat driven pressurized adsorption refrigeration cycle

    Habib, K.

    2015-12-01

    This article presents performance investigation of a waste heat driven two bed pressurised adsorption refrigeration system. In this study, highly porous activated carbon (AC) of type Maxsorb III has been selected as adsorbent while n-butane, R-134a, R410a, R507a and carbon dioxide (CO2) are chosen as refrigerants. All the five refrigerants work at above atmospheric pressure. Among the five pairs studied, the best pairs will be identified which will be used to provide sufficient cooling capacity for a driving heat source temperature above 60°C. Results indicate that for a driving source temperature above 60°C, AC-R410a pair provides highest cooling capacity while AC-CO2 pairs works better when the heat source temperature falls below 60°C.

  3. Magnetic refrigeration materials

    戴闻; 沈保根; 高政祥

    2001-01-01

    Magnetic refrigeration has drawn much attention because of its greater efficiency and higher reliability than the traditional gas-cycle refrigeration technology. Recently, a kind of new materials with a giant magnetocaloric effect in the subroom temperature range, Gd5 (Six Ge1- x)4, was discovered, which boosts the search for high-performance magnetic refrigerants. However, the intermetallic compounds Gd5 (SixGe1 - x )4 belong to the first order transition materials; their performance in practical magnetic refrigeration cycles remains controversial. In this paper the developing tendency of the refrigerants are discussed on the basis of our work.

  4. Materials performance in prototype Thermal Cycling Absorption Process (TCAP) columns

    Two prototype Thermal Cycling Absorption Process (TCAP) columns have been metallurgically examined after retirement, to determine the causes of failure and to evaluate the performance of the column container materials in this application. Leaking of the fluid heating and cooling subsystems caused retirement of both TCAP columns, not leaking of the main hydrogen-containing column. The aluminum block design TCAP column (AHL block TCAP) used in the Advanced Hydride Laboratory, Building 773-A, failed in one nitrogen inlet tube that was crimped during fabrication, which lead to fatigue crack growth in the tube and subsequent leaking of nitrogen from this tube. The Third Generation stainless steel design TCAP column (Third generation TCAP), operated in 773-A room C-061, failed in a braze joint between the freon heating and cooling tubes (made of copper) and the main stainless steel column. In both cases, stresses from thermal cycling and local constraint likely caused the nucleation and growth of fatigue cracks. No materials compatibility problems between palladium coated kieselguhr (the material contained in the TCAP column) and either aluminum or stainless steel column materials were observed. The aluminum-stainless steel transition junction appeared to be unaffected by service in the AHL block TCAP. Also, no evidence of cracking was observed in the AHL block TCAP in a location expected to experience the highest thermal shock fatigue in this design. It is important to limit thermal stresses caused by constraint in hydride systems designed to work by temperature variation, such as hydride storage beds and TCAP columns

  5. 复合制冷循环间冷系统制冷剂/工质的选择论证%A Selection Demonstration of Refrigerant/Medium for Compound Refrigerating Cycle of Indirect Air Cooling System

    杨善让; 雷扬; 赵波; 盛杰; 陈立军

    2012-01-01

    该文旨在从目前80余种制冷剂(包括替代工质)中筛选出能满足复合制冷循环间冷系统f以下简称复间冷)要求的中间传热介质(制冷剂/工质)。筛选步骤如下:1)按制冷剂的臭氧损耗潜势和全球变暖潜势挑选出满足环保要求的“环保型制冷剂”;2)根据环保型制冷剂的物性对复间冷要求的满足程度,挑出合适度比较高的若干种;3)从前两轮筛选出的制冷剂/工质挑出做功能力最大者。最终氨成为3轮筛选唯一胜出的自然物质。考虑到氨的气味对人的呼吸道有刺激性,条件具备时可燃可爆,故再次仔细分析了其安全性,指出其燃爆可防、易防,拟定了相应防范措施,并列举了应用实例。全文结论为:氨物性对复间冷的合适度最高,环境最友好,安全可靠,性价比高。作为复间冷的制冷剂/工质,氨虽非最佳,但目前尚无更佳的替代物。%This paper aims at sieving out the intermediate heat transfer medium (namely refrigerant/medium) for the compound refrigerating cycle from more than 80 refrigerants, which are capable of meeting the compound refrigerating cycle's demands. The sieve course are comprised of 3-steps: 1)According to the values of ozone depletion potential (ODP) and global warming potential (GWP) of refrigerants sifted the so called "environment protection type refrigerant" which meet the environment protection requirements; 2) Based on property parameters of the environment protection type refrigerants/ mediums select those refrigerants which are in accord with requirements of compound refrigerating cycle of indirect air cooling system; 3)The third criterion is that the power capability of medium in inverse refrigerating cycle is the maximum of all the mediums selected by the first and second round of the sifting. At last, the ammonia became the only natural materials which satisfy all

  6. Experimental study of a thermochemical compressor for an absorption/compression hybrid cycle

    Highlights: ► Experimental study of a thermochemical compressor for absorption/compression cycle. ► Spray adiabatic absorber using NH3–LiNO3 solution working fluid. ► It is able to operate between 57 and 110 °C varying concentration between 0.46 and 0.59. ► The increase of absorber pressure decreases the circulation ratio. ► The numerical model performed agrees with the experimental results. -- Abstract: An experimental study of a thermochemical compressor with ammonia–lithium nitrate solution as working fluid has been carried out. This compressor incorporates a single-pass adiabatic absorber and all the heat exchangers are of the plate type: absorber subcooler, generator and solution heat exchanger. The thermochemical compressor has been studied as part of a single-effect absorption chiller hybridized with an in-series low-pressure compression booster. The adiabatic absorber uses fog jet injectors. The generator hot water temperatures for the external driving flow are in the range of 57–110 °C and the absorber pressures range between 429 and 945 kPa. Experimental results are compared with a numerical model showing a high agreement. The performance of the thermochemical compressor, evaluated through the circulation ratio, improves for higher absorber pressures, indicating the potential of pressure boosting. For the same circulation ratio, the driving hot water inlet temperature decreases with the rise of the absorber pressure. The thermochemical compressor, based on an adiabatic absorber, can produce refrigerant with very low driving temperatures, between 57 and 70 °C, what is interesting for solar cooling applications and very low temperature residual heat recovery. Efficiencies and cooling power are offered when this hybrid thermochemical compressor is implemented in a chiller, showing the effect of different operating parameters.

  7. Design of closed-loop nitrogen Joule-Thomson refrigeration cycle for 67 K with sub-atmospheric device

    Lee, C.; Lee, J.; Jeong, S. [Cryogenic Engineering Laboratory, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2013-05-15

    Closed-loop J-T (Joule-Thomson) refrigeration cycle is advantageous compared to common open loop N{sub 2} decompression system in terms of nitrogen consumption. In this study, two closed-loop pure N{sub 2} J-T refrigeration systems with sub-atmospheric device for cooling High Temperature Superconductor (HTS) power cable are investigated. J-T cooling systems include 2-stage compressor, 2-stage precooling cycle, J-T valve and a cold compressor or an auxiliary vacuum pump at the room temperature. The cold compressor and the vacuum pump are installed after the J-T valve to create sub-atmospheric condition. The temperature of 67 K is possible by lowering the pressure up to 24 kPa at the cold part. The optimized hydrocarbon mixed refrigerant (MR) J-T system is applied for precooling stage. The cold head of precooling MR J-T have the temperature from 120 K to 150 K. The various characteristics of cold compressor are investigated and applied to design parameter of the cold compressor. The Carnot efficiency of cold compressor system is calculated as 16.7% and that of vacuum pump system as 16.4%. The efficiency difference between the cold compressor system and the vacuum pump system is due to difference of enthalpy change at cryogenic temperature, enthalpy change at room temperature and different work load at the pre-cooling cycle. The efficiency of neon-nitrogen MR J-T system is also presented for comparison with the sub-atmospheric devices. These systems have several pros and cons in comparison to typical MR J-T systems such as vacuum line maintainability, system's COP and etc. In this paper, the detailed design of the subcooled N{sub 2} J-T systems are examined and some practical issues of the sub-atmospheric devices are discussed.

  8. Exergetic Optimization of a Refrigeration Cycle for Re-Liquefaction of LNG Boil-Off Gas

    Mojtaba Babaelahi

    2010-11-01

    Full Text Available The development of liquefaction process for liquefied natural gas boil-off re-liquefaction plants will be addressed to provide an environmentally friendly and cost effective solution for gas transport. Onboard boil-off gas (BOG re-liquefaction is a new technology that liquefies BOG and returns it to the cargo tanks instead of burning it. Exergetic efficiency optimization for cryogenic refrigeration cycle for re-liquefaction of LNG boil-off gas is performed. Thermodynamic modeling has been performed based on the energy and exergy analyses. Objective problem is developed based on maximization of the plant exergetic efficiency and selected decision variables and constraints. Optimization process is performed using MATLAB genetic algorithm optimization

  9. Supercooling Refrigerator

    1986-01-01

    A Goddard/Philips research project resulted in a refrigeration system which works without seals, lubricants or bearings. The system, originally developed to cool satellite-based scientific instruments, has an extensive range of potential spinoffs. It is called the Stirling Cycle Cryogenic Cooler and eliminates friction by using electronically controlled linear magnetic bearings. Mechanical failure, contamination are eliminated.

  10. Experimental study on solar-powered adsorption refrigeration cycle with activated alumina and activated carbon as adsorbent

    Himsar Ambarita

    2016-03-01

    Full Text Available Typical adsorbent applied in solar-powered adsorption refrigeration cycle is activated carbon. It is known that activated alumina shows a higher adsorption capacity when it is tested in the laboratory using a constant radiation heat flux. In this study, solar-powered adsorption refrigeration cycle with generator filled by different adsorbents has been tested by exposing to solar radiation in Medan city of Indonesia. The generator is heated using a flat-plate type solar collector with a dimension of 0.5 m×0.5 m. Four cases experiments of solar-powered adsorption cycle were carried out, they are with generator filled by 100% activated alumina (named as 100AA, by a mixed of 75% activated alumina and 25% activated carbon (75AA, by a mixed of 25% activated alumina and 75% activated carbon (25AA, and filled by 100% activated carbon. Each case was tested for three days. The temperature and pressure history and the performance have been presented and analyzed. The results show that the average COP of 100AA, 75AA, 25AA, and 100AC is 0.054, 0.056, 0.06, and 0.074, respectively. The main conclusion can be drawn is that for Indonesian condition and flat-plate type solar collector the pair of activated carbon and methanol is the better than activated alumina.

  11. Application of exergetic sustainable index to the quantum irreversible Diesel refrigerator cycles for 1D box system

    Açıkkalp, Emin; Caner, Necmettin

    2015-04-01

    In this paper, an irreversible quantum Diesel refrigerator for a 1D-box system is described and analyzed. The exergetic sustainability index that is the rate of the exergy output from the system to the total exergetic losses including exergy destruction and exergy loss from the system is applied for the first time to an irreversible quantum engine. Other thermodynamic parameters including work input, cooling load, exergy destruction, COP and exergy efficiency are investigated according to the cycle temperatures and numerical results are presented.

  12. Performance of Different Experimental Absorber Designs in Absorption Heat Pump Cycle Technologies: A Review

    Jonathan Ibarra-Bahena

    2014-02-01

    Full Text Available The absorber is a major component of absorption cycle systems, and its performance directly impacts the overall size and energy supplies of these devices. Absorption cooling and heating cycles have different absorber design requirements: in absorption cooling systems, the absorber works close to ambient temperature, therefore, the mass transfer is the most important phenomenon in order to reduce the generator size; on the other hand, in heat transformer absorption systems, is important to recover the heat delivered by exothermic reactions produced in the absorber. In this paper a review of the main experimental results of different absorber designs reported in absorption heat pump cycles is presented.

  13. Feasibility and Basic Design of Solar Integrated Absorption Refrigeration for an Industry

    Akhtar, Saad

    2015-08-28

    This paper presents a review of existing solar cooling technologies and a feasibility study of a solar absorption cooling system for a packaging facility at Tetrapak Lahore, Pakistan. The review includes brief description of existing chiller technologies and solar collectors. The case study includes analysis of the solar potential and design of the cooling system at considered site. The design calculations upon which the feasibility analysis is carried out are solar collector area and type, cooling capacity, cooling area. A comparison is made between solar cooling potential of Pakistan and existing sites all across the globe. Finally an economic analysis is carried out to demonstrate the financial viability of the new cooling system.

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

    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

  15. A GdxHo1−x-based composite and its performance characteristics in a regenerative Ericsson refrigeration cycle

    Highlights: • MCE characteristics of GdxHo1−x alloys with different x are determined. • A promising material compositing with GdxHo1−x alloys is suggested. • Optimal mass ratios of three components in the composite are obtained. • Isothermal magnetic entropy change of the composite is close to a constant inside 28 K. • Thermodynamic performances between GdxHo1−x alloys and the composite are compared. - Abstract: Based on the molecular field theory, de Gennes factor model, and numerical calculation method, the magnetic entropy change and Curie temperature of GdxHo1−x alloys are studied, where x = 0.80, 0.91, and 1. The composite magnetic material consists of Gd0.80Ho0.20, Gd0.91Ho0.09, and Gd, according to the definite mass ratios y1, y2 and y3. The calculation results show that there exist optimal mass ratios y1opt, y2opt, and y3opt and their values depend on the applied magnetic field μ0H1. When μ0H1 = 2 T, y1opt, y2opt, and y3opt are equal to 0.24, 0.17, and 0.59, respectively. It is found that the total magnetic entropy change of the composite magnetic material 0.24Gd0.80Ho0.20⋅0.17Gd0.91Ho0.09⋅0.59Gd under 2 T applied magnetic field change is close to a constant in the region between 265 K and 293 K. Furthermore, the regenerative Ericsson refrigeration cycle using the composite magnetic material as the working substance is put forward and its cyclic performances including the net cooling quantity Qnet, coefficient of performance (COP), etc. are analyzed. The results obtained show that for the regenerative Ericsson refrigeration cycle using the composite magnetic material as the working substance, there are not only a large temperature span (28 K) but also a large net cooling quantity (1008 J/kg under 2 T applied magnetic field) and a large COP (9.01), which are, respectively, larger than those of regenerative Ericsson refrigeration cycles using Gd0.80Ho0.20, Gd0.91Ho0.09 or Gd. Moreover, the effect of the applied magnetic field on the

  16. Multi-phonon-assisted absorption and emission in semiconductors and its potential for laser refrigeration

    Khurgin, Jacob B

    2014-01-01

    Laser cooling of semiconductors has been an elusive goal for many years, and while attempts to cool the narrow gap semiconductors such as GaAs are yet to succeed, recently, net cooling has been attained in a wider gap CdS. This raises the question of whether wider gap semiconductors with higher phonon energies and stronger electron-phonon coupling are better suitable for laser cooling. In this work we develop a straightforward theory of phonon-assisted absorption and photoluminescence of semiconductors that involves more than one phonon and use to examine wide gap materials, such as GaN and CdS and compare them with GaAs. The results indicate that while strong electron-phonon coupling in both GaN and CdS definitely improves the prospects of laser cooling, large phonon energy in GaN may be a limitation, which makes CdS a better prospect for laser cooling.

  17. 新型太阳能增压吸收式制冷循环%A New Solar-Supercharge Absorption Refrigerator Circle

    刘辉; 李长胜

    2011-01-01

    提出了一个以NH3-LiNO3为工质对、压缩蒸发器出口冷剂蒸气、利用太阳能进行制冷的新循环,采用数值计算的方法对新循环的性能指数、(火用)效率、电热比和冷却水量进行了研究,计算结果表明补偿相当于0.7%~10.68%太阳能能量的电能可使热源进口温度自95℃降低16℃~22℃,新循环的性能指数在0.495~1.201之间,(火用)效率在0.245~0.122之间,冷却水流量随驱动热源进口温度的降低基本呈线性从7.24kg/s减少至3.74kg/s.克服了传统循环受限于太阳能波动的不足,具有很好的节能效益和实践价值.%A new absorption refrigeration circle is proposed, which takes NH3-LiNO3 as the working fluids, compresses the refrigerant vapor out of evaporator and is driven by solar energy. The COP, exergy efficiency, the ratio of the electricity to heat and the flow rate of the cooling water in the proposed circle is numerically studied. The results reveals that: taking electricity about 0.7 to 10.68 percent of the solar energy can reduce 16 to 22 °C of input temperature of the driven water from 95 ℃; the COP is between 0.495 and 1.201 while the exergy efficiency is between 0.245 and 0.122; the flow rate of cooling water will be decreased linearly from 7.24kg/s to 3.74kg/s with the decrease of the temperature of driven water. This circle overcomes the shortage that the traditional solar cycle is subjected to the fluctuation of solar, so it has good energy efficiency and practical value.

  18. Effect of Suction Nozzle Pressure Drop on the Performance of an Ejector-Expansion Transcritical CO2 Refrigeration Cycle

    Zhenying Zhang

    2014-08-01

    Full Text Available The basic transcritical CO2 systems exhibit low energy efficiency due to their large throttling loss. Replacing the throttle valve with an ejector is an effective measure for recovering some of the energy lost in the expansion process. In this paper, a thermodynamic model of the ejector-expansion transcritical CO2 refrigeration cycle is developed. The effect of the suction nozzle pressure drop (SNPD on the cycle performance is discussed. The results indicate that the SNPD has little impact on entrainment ratio. There exists an optimum SNPD which gives a maximum recovered pressure and COP under a specified condition. The value of the optimum SNPD mainly depends on the efficiencies of the motive nozzle and the suction nozzle, but it is essentially independent of evaporating temperature and gas cooler outlet temperature. Through optimizing the value of SNPD, the maximum COP of the ejector-expansion cycle can be up to 45.1% higher than that of the basic cycle. The exergy loss of the ejector-expansion cycle is reduced about 43.0% compared with the basic cycle.

  19. Performance characteristics of an irreversible regenerative magnetic Brayton refrigeration cycle using Gd0.74Tb0.26 as the working substance

    Diguet, Gildas; Lin, Guoxing; Chen, Jincan

    2012-10-01

    The cycle model of an irreversible regenerative magnetic Brayton refrigerator using Gd0.74Tb0.26 as the working substance is established. Based on the experimental characteristics of iso-field heat capacities of the material Gd0.74Tb0.26 at 0 T and 2 T, the corresponding iso-field entropies are calculated and the thermodynamic performance of an irreversible regenerative magnetic Brayton refrigeration cycle is investigated. The effects of the irreversibilities in the two adiabatic processes and non-perfect regenerative process of the magnetic Brayton refrigeration cycle on the cooling quantity, the heat quantity released to the hot reservoir, the net cooling quantity and the coefficient of performance are discussed in detail. Some significant results are obtained.

  20. Stirling Refrigerator

    Kagawa, Noboru

    A Stirling cooler (refrigerator) was proposed in 1862 and the first Stirling cooler was put on market in 1955. Since then, many Stirling coolers have been developed and marketed as cryocoolers. Recently, Stirling cycle machines for heating and cooling at near-ambient temperatures between 173 and 400K, are recognized as promising candidates for alternative system which are more compatible with people and the Earth. The ideal cycles of Stirling cycle machine offer the highest thermal efficiencies and the working fluids do not cause serious environmental problems of ozone depletion and global warming. In this review, the basic thermodynamics of Stirling cycle are briefly described to quantify the attractive cycle performance. The fundamentals to realize actual Stirling coolers and heat pumps are introduced in detail. The current status of the Stirling cycle machine technologies is reviewed. Some machines have almost achieved the target performance. Also, duplex-Stirling-cycle and Vuilleumier-cycle machines and their performance are introduced.

  1. Comparative Study on Solar Collector’s Configuration for an Ejector-Refrigeration Cycle

    Raffles Senjaya; I Made Astina

    2008-01-01

    Solar collector’s configuration plays important role on solar-powered refrigeration systems to work as heat source for generator. Three types of solar collector consisting of flat plate, evacuated tube, and compound parabolic solar collectors are compared to investigate their performances. The performances consist of the behavior of heat which can be absorbed by the collectors, heat loss from the collectors and outlet temperature of working fluid at several slopes of the solar collectors. The...

  2. Application of a solar refrigeration system by absorption for the air conditioning of buildings

    Machielsen, Cees H. M [Delft University of Technology, Mekelweg (Netherlands); Hagendijk, Andre E [Consultancy and Research (Netherlands)

    2000-07-01

    This paper describes the Sofri project, a cooperation between Ceeran Ltd and The Delft University of Technology. The main objective of this project is to develop the necessary knowledge and experience to commercialize solar-assisted air conditioning and dehumidification systems in the Dutch Caribbean. The project is motivated by the present needs of the Dutch Caribbean for renewable energy sources and the fact that the Caribbean has a high and uniform insolation throughout the year. Furthermore, hotels and offices in this area use more than 40% of their energy for air-conditioning purposes. Therefore solar-assisted air conditioning systems are a logic approach in reducing the energy demand and to lower the peak electricity reducing the energy demands for the local power station. Ceeran Ltd has the objective to reach full commercialization of the proposed technologies in the Dutch Caribbean. The research is concentrated on liquid absorption machines and solar collection systems such as flat plates with selective surfaces, heat pipe evacuated tubes flat plate collectors, and Compound Parabolic Concentrators. The first demonstration unit is planned to be installed in an office building in Curacao. The installation consists of a 35 kW LiBr/H{sub 2}O absorption machine driven by 100 m{sup 2} flat pate collectors with a gas backup system. The system will provide comfort air-conditioning for this these type of office buildings during daytime. [Spanish] Este documento describe el proyecto SOFRI, una cooperacion entre Ceeran, Ltd, y la Universidad Tecnologica del Delft. El principal objetivo de este proyecto es el de desarrollar el conocimiento necesario y la experiencia para comercializar los sistemas de aire acondicionado y deshumidificacion ayudados por la energia solar en el Caribe Holandes. Este proyecto ha sido motivado por las actuales necesidades del Caribe Holandes de fuentes de energia renovable y por el hecho de que el Caribe tiene una alta y uniforme insolacion

  3. Prospects in magnetic refrigeration

    Cryogenic applications extend over the whole range of power types: from small power types with infra-red detection. Satellite communication, cryopumping and the medical applications of superconductors to the large power types with cryogenic alternators and superconductor magnets for fusion. The question actually arises wether magnetic refrigeration cycles can have higher reliability and higher efficiency than classical gas refrigerating machines. Before discussing the state of the art, we will point out some general thermodynamic conditions that have to be respected for magnetic cycles as for gas cycles. Magnetic Carnot cycle refrigerators are now capable of pumping heat efficiently when all the cycle is executed in liquid helium temperature range

  4. Refrigerator Based on Chemisorption

    Jones, Jack A.

    1987-01-01

    Reversible chemical reaction generates pressurized oxygen for cooling. Concept for cryogenic refrigerator based on chemical absorption of oxygen by praseodymium/cerium oxide (PCO) compound. Refrigerator produces cryogenic liquid for cooling infrared sensors. Also used for liquefying air and separating oxygen from nitrogen in air. In chemisorption refrigerator, PCO alternately absorbs and desorbs oxygen depending on whether cooled or heated. One pair of compressors accepts oxygen while others releases it. Compressed oxygen liquefied when precooked and expanded.

  5. Molecular-Level Computer Simulation of a Vapor-Compression Refrigeration Cycle

    Figueroa-Gerstenmaier, S.; Francova, M.; Kowalski, M.; Lísal, Martin; Nezbeda, Ivo; Smith, W.R.

    2007-01-01

    Roč. 259, č. 2 (2007), s. 195-200. ISSN 0378-3812 R&D Projects: GA ČR(CZ) GA203/05/0725; GA AV ČR 1ET400720409; GA AV ČR 1ET400720507 Grant ostatní: NRCC(CA) OGP 1041 Institutional research plan: CEZ:AV0Z40720504 Source of funding: V - iné verejné zdroje Keywords : alternative refrigerants * joule- thomson expansion * adiabatic process Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.506, year: 2007

  6. Solutions for Liquid Nitrogen Pre-Cooling in Helium Refrigeration Cycles

    Wagner, U

    2000-01-01

    Pre-cooling of helium by means of liquid nitrogen is the oldest and one of the most common process features used in helium liquefiers and refrigerators. Its two principle tasks are to allow or increase the rate of pure liquefaction, and to permit the initial cool-down of large masses to about 80 K. Several arrangements for the pre-cooling process are possible depending on the desired application. Each arrangement has its proper advantages and drawbacks. The aim of this paper is to review the possible process solutions for liquid nitrogen pre-cooling and their particularities.

  7. Neon helium mixtures as a refrigerant for the FCC beam screen cooling: comparison of cycle design options

    Kloeppel, S.; Quack, H.; Haberstroh, C.; Holdener, F.

    2015-12-01

    In the course of the studies for the next generation particle accelerators, in this case the Future Circular Collider for hadron-hadron interaction (FCC-hh), different aspects are being investigated. One of these is the heat load on the beam screen, which results mainly from the synchrotron radiation. In case of the FCC-hh, a heat load of 6 MW is expected. The heat has to be absorbed at 40 to 60 K due to vacuum restrictions. In this range, refrigeration is possible with both helium and neon. Our investigations are focused on a mixed refrigerant of these two components, which combines the advantages of both. Especially promising is the possible substitution of the oil flooded screw compressors by more efficient turbo compressors. This paper investigates different flow schemes and mixture compositions with respect to complexity and efficiency. Furthermore, thermodynamic aspects, e.g. whether to use cold or warm secondary cycle compressors are discussed. Additionally, parameters of the main compressor are established.

  8. A Possible 1.8 K Refrigeration Cycle for the Large Hadron Collider

    Millet, F; Tavian, L; Wagner, U

    1998-01-01

    The Large Hadron Collider (LHC) under construction at the European Laboratory for Particle Physics, CERN, will make use of superconducting magnets operating below 2.0 K. This requires, for each of the eight future cryogenic installations, an isothermal cooling capacity of up to 2.4 kW obtained by vaporisation of helium II at 1.6 kPa and 1.8 K. The process design for this cooling duty has to satisfy several demands. It has to be adapted to four already existing as well as to four new refrigerators. It must cover a dynamic range of one to three, and it must to allow continuous pump-down from 4.5 K to 1.8 K. A possible solution, as presented in this paper, includes a combination of cold centrifugal and warm volumetric compressors. It is characterised by a low thermal load on the refrigerator, and a large range of adaptability to different operation modes. The expected power factor for 1.8 K cooling is given, and the proposed control strategy is explained.

  9. Construction and calibration of a 12 T pulsed magnet integrated with a 4 K closed-cycle refrigerator.

    Murthy, O V S N; Venkataraman, V

    2007-11-01

    A low cost 12 T pulsed magnet system has been integrated with a closed-cycle helium refrigerator for performing magnetotransport measurements. Minimal delay between pulses and ac current excitation with software lock-in to reduce noise enables quick but accurate measurements to be performed at temperatures of 4-300 K up to 12 T. An additional pulsed magnet operating with a liquid nitrogen cryostat extends the range up to 19 T. The instrument has been calibrated against a commercial superconducting magnet by comparing quantum Hall effect data in a p-channel SiGe/Si heterostructure, and common issues arising out of pulsed magnet usage have been addressed. The versatility of the system is demonstrated through magnetotransport measurements in a variety of samples such as heterostructures, narrow gap semiconductors, and those exhibiting giant magnetoresistance. PMID:18052486

  10. Performance studies on mechanical + adsorption hybrid compression refrigeration cycles with HFC 134a

    Banker, N.D.; Dutta, P.; Srinivasan, K. [Department of Mechanical Engineering, Indian Institute of Science, Bangalore 560 012 (India); Prasad, M. [Thermal Systems Division, ISRO Satellite Centre, Bangalore 560 017 (India)

    2008-12-15

    This paper presents the results of an investigation on the efficacy of hybrid compression process for refrigerant HFC 134a in cooling applications. The conventional mechanical compression is supplemented by thermal compression using a string of adsorption compressors. Activated carbon is the adsorbent for the thermal compression segment. The alternatives of bottoming either mechanical or thermal compression stages are investigated. It is shown that almost 40% energy saving is realizable by carrying out a part of the compression in a thermal compressor compared to the case when the entire compression is carried out in a single-stage mechanical compressor. The hybrid compression is feasible even when low grade heat is available. Some performance indictors are defined and evaluated for various configurations. (author)

  11. Dynamic simulation of natural convection bypass two-circuit cycle refrigerator-freezer and its application Part I: Component models

    In order to reduce the greenhouse gas emissions, efficient household refrigerator/freezers (RFs) are required. Bypass two-circuit cycle RFs with one compressor are proved to be more efficient than two-evaporator in series cycle RFs. In order to study the characteristics and improve the design of bypass two-circuit cycle RFs, a dynamic model is developed in this paper. In part I, the mathematic models of all components are presented, considering not only the accuracy of the models but also the computation stability and speed to solve the models. An efficiency model that requires a single calorimeter data point at the standard test condition is employed for compressor. A multi-zone model is employed for condenser and for evaporator, with its wall thermal capacity considered by effective metal method. The approximate integral analytic model is employed for adiabatic capillary tube, and the effective inlet enthalpy method is used to transfer the non-adiabatic capillary tube to adiabatic capillary tube. The z-transfer function model is employed for cabinet load calculation

  12. Energetic and Exergetic Analysis of an Ejector-Expansion Refrigeration Cycle Using the Working Fluid R32

    Zhenying Zhang

    2015-07-01

    Full Text Available The performance characteristics of an ejector-expansion refrigeration cycle (EEC using R32 have been investigated in comparison with that using R134a. The coefficient of performance (COP, the exergy destruction, the exergy efficiency and the suction nozzle pressure drop (SNPD are discussed. The results show that the application of an ejector instead of a throttle valve in R32 cycle decreases the cycle’s total exergy destruction by 8.84%–15.84% in comparison with the basic cycle (BC. The R32 EEC provides 5.22%–13.77% COP improvement and 5.13%–13.83% exergy efficiency improvement respectively over the BC for the given ranges of evaporating and condensing temperatures. There exists an optimum suction nozzle pressure drop (SNPD which gives a maximum system COP and volumetric cooling capacity (VCC under a specified condition. The value of the optimum SNPD mainly depends on the efficiencies of the ejector components, but is virtually independent of evaporating temperature and condensing temperature. In addition, the improvement of the component efficiency, especially the efficiencies of diffusion nozzle and the motive nozzle, can enhance the EEC performance.

  13. High temperature refrigerator

    Steyert, Jr., William A.

    1978-01-01

    A high temperature magnetic refrigerator which uses a Stirling-like cycle in which rotating magnetic working material is heated in zero field and adiabatically magnetized, cooled in high field, then adiabatically demagnetized. During this cycle said working material is in heat exchange with a pumped fluid which absorbs heat from a low temperature heat source and deposits heat in a high temperature reservoir. The magnetic refrigeration cycle operates at an efficiency 70% of Carnot.

  14. Analysis of a combined power and refrigeration cycle by the exergy method

    The exergy analysis method was applied in order to evaluate the new combined cycle proposed by Goswami [Solar thermal technology: present status and ideas for the future. Energy Sources 1998;20:137-45], using Hasan-Goswami-Vijayaraghavan parameters. This new combined cycle was proposed to produce both power and cooling simultaneously with only one heat source and using ammonia-water mixture as the working fluid. The simulation of the cycle was carried out in the process simulator ASPEN Plus. The Redlich-Kwong-Soave equation of state was used to calculate the thermodynamic properties. The cycle was simulated as a reversible as well as an irreversible process to clearly show the effect of the irreversibilities in each component of the cycle. At the irreversible process two cases were considered, changing the environmental temperature. However, in order to know the performance of the new cycle at different conditions of operation, the second irreversible case was analyzed varying the rectification temperatures, the isentropic efficiency of the turbine and the return temperature of the chilled water. Exergy effectiveness values of ∼53% and ∼51% were obtained for the irreversible cycles; with heat input requirements at temperatures of 125 and 150 deg. C. Solar collectors or waste heat are suggested as heat sources to operate the cycle

  15. Experimental Investigation of a Three-Bed Adsorption Refrigeration Chiller Employing an Advanced Mass Recovery Cycle

    Atsushi Akisawa

    2009-07-01

    Full Text Available The performance of an advanced three-bed adsorption chiller with a mass recovery cycle has been experimentally investigated in the present study. The temperature and pressure of various components of the chiller were monitored to observe the dynamic behaviour of the chiller. The performances in terms of the coefficient of performance (COP and specific cooling power (SCP were compared with a conventional single stage. The results show that the proposed cycle produces COP and SCP values superior to those of the conventional single stage cycle for heat source temperature below 75 °C.

  16. Comparative Study on Solar Collector’s Configuration for an Ejector-Refrigeration Cycle

    Raffles Senjaya

    2008-05-01

    Full Text Available Solar collector’s configuration plays important role on solar-powered refrigeration systems to work as heat source for generator. Three types of solar collector consisting of flat plate, evacuated tube, and compound parabolic solar collectors are compared to investigate their performances. The performances consist of the behavior of heat which can be absorbed by the collectors, heat loss from the collectors and outlet temperature of working fluid at several slopes of the solar collectors. The new accurate analysis method of heat transfer is conducted to predict the performance of the solar collectors. The analysis is based on several assumptions, i.e. sky condition at Bandung is clear and not raining from 08.00 until 17.00 and thermal resistance at cover and absorber plate is negligible. The numerical calculation results confirm that performance of the evacuated tubes solar collector at the same operating conditions is higher than the others. For the case of an evacuated-tubes solar collector system with aperture area of 3.5 m2, the maximum heat which can be absorbed is 3992 W for the highest solar intensity of 970 W/m2 at 12.00 and horizontal position of the solar collector. At this condition, the highest outlet temperature of water is 347.15 K with mass flow rate 0.02 kg/s and inlet temperature 298 K.

  17. Experimental Investigation of a Three-Bed Adsorption Refrigeration Chiller Employing an Advanced Mass Recovery Cycle

    Atsushi Akisawa; Yuki Ueda; Aep Saepul Uyun; Takahiko Miyazaki

    2009-01-01

    The performance of an advanced three-bed adsorption chiller with a mass recovery cycle has been experimentally investigated in the present study. The temperature and pressure of various components of the chiller were monitored to observe the dynamic behaviour of the chiller. The performances in terms of the coefficient of performance (COP) and specific cooling power (SCP) were compared with a conventional single stage. The results show that the proposed cycle produces COP and SCP values super...

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

    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

  19. Modelling and simulation of an absorption cycle with a blow pump; Modellierung und Simulation eines Absorptionskreislaufes mit einer Blasenpumpe

    Buecherl, Markus

    2011-07-01

    Diffusion-absorption refrigerators are commonly operated with ammonia and water. If a ionic liquid with negligible vapour pressure is substituted for water, the rectifier will be unnecessary. In the context of a diploma thesis, a diffusion-absorption refrigerator with a blower pump and ammonia and a ionic liquid as working fluid was modelled and simulated. For this, three models were selected from the relevant literature and compared. Changes in COP as a result of varied operating parameters were investigated as well. It was shown that it is possible, in principle, to operate a diffusion-absorption refrigerator with a ionic liquid. [German] Diffusions-Absorptions-Kaeltemaschinen werden in der Regel mit dem Arbeitsstoffpaar Ammoniak-Wasser betrieben. Ersetzt man das Absorptionsmittel Wasser gegen eine ionische Fluessigkeit, die nur einen vernachlaessigbaren Dampfdruck besitzt, kann man den Rektifikator einsparen. Im Rahmen einer Diplomarbeit wurde eine Diffusions-Absorptions-Kaeltemaschine mit einer Blasenpumpe und dem Arbeitsstoffpaar Ammoniak-Ionische Fluessigkeit modelliert und simuliert. Hierfuer wurden drei Modelle aus der Literatur ausgewaehlt. Diese Modelle wurden untereinander verglichen. Ausserdem wurde die Veraenderung des COP bei der Variation der Betriebsparameter fuer diese Berechnungsmodelle untersucht. Es konnte gezeigt werden, dass es prinzipiell moeglich ist, eine Diffusions-Absorptions-Kaeltemaschine mit ionischer Fluessigkeit zu betreiben.

  20. Magnetic refrigerator for hydrogen liquefaction

    Matsumoto, Koichi; Kondo, T.; Yoshioka, S; Kamiya, K.; Numazawa, T.

    2009-01-01

    Magnetic refrigeration which is based on the magnetocaloric effect of solids has the potential to achieve high thermal efficiency for hydrogen liquefaction. We have been developing a magnetic refrigerator for hydrogen liquefaction which cools down hydrogen gas from liquid natural gas temperature and liquefies at 20 K. The magnetic liquefaction system consists of two magnetic refrigerators: Carnot magnetic refrigerator (CMR) and active magnetic regenerator (AMR) device. CMR with Carnot cycle s...

  1. Performance analysis of an absorption power cycle for ocean thermal energy conversion

    Highlights: • An absorption power cycle is proposed for ocean thermal energy conversion (OTEC). • The performance of this cycle is valued by theoretical analysis. • This proposed cycle can be driven with a lower temperature difference. • This cycle provides a potential of broadening the scope of the OTEC application. - Abstract: An absorption power cycle with two ejectors is proposed for ocean thermal energy conversion. The ammonia–water is used as the working fluid. The ejectors are driven by vapor and solution from the sub-generator. Based on the first and second law, the mathematical model for this cycle is developed and theoretical analysis is conducted to evaluate the effects of thermodynamic parameters on the performance of this cycle. Results show that the absorption temperature is increased by 2.0–6.5 °C by employing the two-stage ejector sub-cycle, which indicates that this proposed cycle can be driven with a lower temperature difference. Further, the thermal efficiency, net thermal efficiency and exergy efficiency of this cycle can reach to 4.17%, 3.10% and 39.92% respectively. Besides, the generation pressure, the heating source temperature, the solution concentration, and the expansion ratio, as well as the entrainment ratio of the first stage ejector have significant effects on the absorption temperature, the thermal efficiency, the exergy efficiency and the exergy loss of this cycle. In addition, 49.80% of exergy loss in this proposed cycle occurs in the generators and reheater, followed by the ejectors of 36.12%

  2. Studi Variasi Flowrate Refrigerant pada Sistem Organic Rankine Cycle dengan Fluida Kerja R-123

    Aria Halim Pamungkas

    2013-09-01

    Full Text Available Saat ini kelangkaan sumber energi fosil telah menjadi isu utama di seluruh dunia. Hal tersebut memberikan dampak yang signifikan di setiap aspek kehidupan dan salah satunya adalah di bidang pembangkit listrik. Salah satu sistem pembangkit listrik yang tidak menggunakan energi fosil adalah Organic rankine cycle (ORC. Pada penelitian ini dilakukan dengan metode eksperimental pada suatu sistem Organic rankine cycle yang telah dibangun. Penelitian ini yang divariasikan adalah flowrate dari fluida kerja dalam hal ini R-123. Variasi flowrate yang digunakan yaitu 3-1 GPM (Galon per menit dengan penurunan 0,5 GPM setiap pengambilan data. Hasil yang didapatkan dari penelitian ini berupa grafik–grafik daya pada turbin, kondensor, pompa dan evaporator, efisiensi siklus dan back work ratio  fungsi flowrate fluida kerja. Efisiensi siklus tertinggi adalah 5,86% yang terjadi pada flowrate 3 GPM dan efisiensi siklus terendah adalah 4,32% yang terjadi pada flowrate 1 GPM.

  3. Further investigations of an ammonia/water absorption refrigerator; Weiterfuehrende Untersuchungen an einer Ammoniak/Wasser-Absorptionskaeltemaschine

    Koller, T.; Schmid, F.; Zetzsche, M.; Spindler, K. [Stuttgart Univ. (Germany). Inst. fuer Thermodynamik und Waermetechnik

    2011-07-01

    The Institute of Thermodynamics and Thermal Engineering of Stuttgart university developed a solar refrigerating absorber with ammonia/water as working pair. The continued development was regularly presented at the DKV conference, and data and simulations were brought up for discussion. This contribution presents the current status. The solvent circulation rate was enhanced and the control regime adapted. Measures were discussed and evaluated for different plant configurations. The function of the refrigerant reservoir and its influence on the number of potential operating points was discussed, and boundary conditions were investigated that were not considered in the design of the ITW refrigerating absorber, i.e. heating temperatures of between 130 and 150 C and recirculation cooling temperatures up to 45 C. [German] Das Institut fuer Thermodynamik und Waermetechnik der Universitaet Stuttgart entwickelt eine solar angetriebene Absorptionskaeltemaschine mit dem Arbeitsstoffpaar Ammoniak/Wasser. Die fortlaufende Entwicklung der Kaeltemaschine wurde in den letzten Jahren regelmaessig auf der DKV-Tagung vorgestellt und anhand von Messdaten und Simulationen diskutiert. Im aktuellen Beitrag werden, anhand von Messdaten, weitere Entwicklungsschritte der Absorptionskaeltemaschine vorgestellt und bewertet. Es wurde der Loesungsmittelumlauf erhoeht und eine Anpassung der Regelung vorgenommen. Mit einem Vergleich zwischen zwei Anlagenkonfigurationen werden die Massnahmen diskutiert und bewertet. Des Weiteren wird auf die Funktion des Kaeltemittel-Reservoirs und dessen Einfluss auf die Vielfalt an moeglichen Betriebspunkten eingegangen. Zudem beinhaltet dieser Beitrag Untersuchungen zu Randbedingungen die nicht der Auslegung der Absorptionskaeltemaschine des ITW entsprechen. Diese sind Heiztemperaturen zwischen 130 und 150 C und Rueckkuehltemperaturen bis zu 45 C.

  4. Optimal refrigerator.

    Allahverdyan, Armen E; Hovhannisyan, Karen; Mahler, Guenter

    2010-05-01

    We study a refrigerator model which consists of two n -level systems interacting via a pulsed external field. Each system couples to its own thermal bath at temperatures T h and T c, respectively (θ ≡ T c/T h Carnot efficiency [formula: see text]. The lower bound is reached in the equilibrium limit θ → 1. The Carnot bound is reached (for a finite power and a finite amount of heat transferred per cycle) for ln n > 1. If the above maximization is constrained by assuming homogeneous energy spectra for both systems, the efficiency is bounded from above by ζ CA and converges to it for n > 1. PMID:20866207

  5. A closed-cycle dilution refrigerator with free-space and fiber optical access for quantum optomechanics experiments at 25mK

    Groeblacher, Simon; Wieczorek, Witlef; Christ, Peter; Buehler, Matthias; Wernicke, Doreen; Hoehne, Jens; Aspelmeyer, Markus

    2011-03-01

    We report on the operation of a closed-cycle dilution refrigerator for quantum optomechanics experiments at 25mK. The dilution fridge is accessible both via free-space as well as fiber coupling, allowing us to perform a variety of optical experiments at low temperatures. It is designed to vibrationally isolate the experiment allowing for stable operation of a high-finesse optical cavity. This enables us to perform cavity-optomechanics experiments at ultra-low temperatures.

  6. Properties and Cycle Performance of Refrigerant Blends Operating Near and Above the Refrigerant Critical Point, Task 2: Air Conditioner System Study

    Piotr A. Domanski; W. Vance Payne

    2002-10-31

    The main goal of this project was to investigate and compare the performance of an R410A air conditioner to that of an R22 air conditioner, with specific interest in performance at high ambient temperatures at which the condenser of the R410A system may be operating above the refrigerant's critical point. Part 1 of this project consisted of conducting comprehensive measurements of thermophysical for refrigerant R125 and refrigerant blends R410A and R507A and developing new equation of state formulations and mixture models for predicting thermophysical properties of HFC refrigerant blends. Part 2 of this project conducted performance measurements of split-system, 3-ton R22 and R410A residential air conditioners in the 80 to 135 F (27.8 to 57.2 C) outdoor temperature range and development of a system performance model. The performance data was used in preparing a beta version of EVAP-COND, a windows-based simulation package for predicting performance of finned-tube evaporators and condensers. The modeling portion of this project also included the formulation of a model for an air-conditioner equipped with a thermal expansion valve (TXV). Capacity and energy efficiency ratio (EER) were measured and compared. The R22 system's performance was measured over the outdoor ambient temperature range of 80 to 135 F (27.8 to 57.2 C). The same test range was planned for the R410A system. However, the compressor's safety system cut off the compressor at the 135.0 F (57.2 C) test temperature. The highest measurement on this system was at 130.0 F (54.4 C). Subsequently, a custom-manufactured R410A compressor with a disabled safety system and a more powerful motor was installed and performance was measured at outdoor temperatures up to 155.0 F (68.3 C). Both systems had similar capacity and EER performance at 82.0 F (27.8 C). The capacity and EER degradation of both systems were nearly linearly dependent with rising ambient outdoor ambient test temperatures. The

  7. Performance of evaporator plates, refrigerant distributors and expansion valves in the refrigeration cycle; Verhalten von Plattenverdampfer, Kaeltemittelverteiler und Expansionsventil im Kaeltemittelkreislauf

    Krusche, K. [Cetetherm Waermetauschersysteme GmbH, Hamburg (Germany); Osthues, J. [Ernst Flitsch GmbH + Co., Fellbach (Germany)

    1997-05-01

    A large variety of heat exchanger types are used in refrigeration engineering. In view of their high specific heat transfer capacity and hermetically sealed construction, soldered heat exchanger plate units are used increasingly frequently as evaporators, condenser, for heat removal, subcooling, intermediate cooling or internal heat exchange. In order to ensure efficient performance of these units, both heat transfer fluids should have a high density. The plate heat exchanger consists of a number of parallel ducts across which the two-phase refrigerant flowing from the expansion valve to the evaporator must be evenly distributed. (orig./HW) [Deutsch] In der Kaeltetechnik kommt eine Vielzahl von Waermeaustauscherbauarten zum Einsatz. Bedingt durch die hohe spezifische Waermeuebertragungsleistung und die hermetische Bauart setzt man in zunehmendem Masse geloetete Plattenwaermeaustauscher als Verdampfer, Kondensator, Enthitzer, Unterkuehler, Zwischenkuehler oder inneren Waermeaustauscher ein. Eine Voraussetzung fuer den effektiven Einsatz der hier behandelten geloeteten Plattenwaermeaustauscher ist, dass beide an der Waermeuebertragung beteiligten Medien eine hohe Dichte haben. Der Plattenverdampfer besteht aus einer Mehrzahl paralleler Kanaele, auf die das zweiphasige Kaeltemittel, das dem Verdampfer vom Expansionsventil zugefuehrt wird, gleichmaessig verteilt werden muss. (orig./HW)

  8. A cycle configuration for large-scale helium refrigerator for fusion devices towards complete mitigation of the effects of pulsed heat load

    Dutta, Rohan, E-mail: rohankrdutta@gmail.com; Ghosh, Parthasarathi; Chowdhury, Kanchan

    2013-11-15

    Highlights: • Large-scale helium refrigerators are subjected to pulsed heat load from fusion devices. • As a result plants may trip hindering continuous cooling of superconducting magnets. • Proposed a cycle configuration for complete mitigation of such effects in plants. • It includes cold-compressor, supercritical buffer and parallel heat exchanger. • Dynamic simulation revealed almost complete mitigation can be obtained. -- Abstract: Large-scale helium refrigerators in fusion devices work in pulsed heat load condition. The immediate effect of pulsed heat load is mass flow rate fluctuation at the low pressure return stream to the cold-box of the refrigerator. As a result, thermodynamic properties of all the intermediate state points of the cold-box vary widely and may go beyond operating limits. Therefore, for continuous operation, the refrigerators need modification in cycle configuration in order to mitigate the effects of pulsed heat load generated out of the operation of the fusion devices. A number of mitigation techniques exist and none of them is capable of mitigating the mass flow rate fluctuation completely. However, combinations of two or more methods have been found to be effective in mitigation of the effects of pulsed load to the maximum possible extent. In this paper, a cold-end configuration has been proposed that is constituted of combination of different mitigation schemes proposed in previous works. Dynamic simulations are performed to predict the performance of the modified cycle configuration and for validation of the concept towards achievement of complete mitigation. Results of the work have revealed that through the proposed cold-end configuration, almost complete mitigation can be obtained.

  9. A cycle configuration for large-scale helium refrigerator for fusion devices towards complete mitigation of the effects of pulsed heat load

    Highlights: • Large-scale helium refrigerators are subjected to pulsed heat load from fusion devices. • As a result plants may trip hindering continuous cooling of superconducting magnets. • Proposed a cycle configuration for complete mitigation of such effects in plants. • It includes cold-compressor, supercritical buffer and parallel heat exchanger. • Dynamic simulation revealed almost complete mitigation can be obtained. -- Abstract: Large-scale helium refrigerators in fusion devices work in pulsed heat load condition. The immediate effect of pulsed heat load is mass flow rate fluctuation at the low pressure return stream to the cold-box of the refrigerator. As a result, thermodynamic properties of all the intermediate state points of the cold-box vary widely and may go beyond operating limits. Therefore, for continuous operation, the refrigerators need modification in cycle configuration in order to mitigate the effects of pulsed heat load generated out of the operation of the fusion devices. A number of mitigation techniques exist and none of them is capable of mitigating the mass flow rate fluctuation completely. However, combinations of two or more methods have been found to be effective in mitigation of the effects of pulsed load to the maximum possible extent. In this paper, a cold-end configuration has been proposed that is constituted of combination of different mitigation schemes proposed in previous works. Dynamic simulations are performed to predict the performance of the modified cycle configuration and for validation of the concept towards achievement of complete mitigation. Results of the work have revealed that through the proposed cold-end configuration, almost complete mitigation can be obtained

  10. Modeling of Artificial Neural Network for Predicting Specific Heat capacity of working fluid LiBr-H2O used in Vapor Absorption Refrigeration System

    Dheerendra Vikram Singh

    2011-05-01

    Full Text Available The objective of this work is to model an artificial neural network (ANN to predict the value of specific heat capacity of working fluid LiBr-H2O used in vapour absorption refrigeration systems. A feed forward back propagation algorithm is used for the network, which is most popular for ANN. The consistence between experimental and ANN’s approach result was achieved by a mean relative error -0.00573, sum of the squares due to error0.00321, coefficient of multiple determination R-square 0.99961and root mean square error 0.01573 for test data. These results had been achieved in Matlab environment and the use of derived equations in any programmable language for deriving the specific heat capacity of LiBr-H2O solution.

  11. Coefficient of Performance Optimization of Single-Effect Lithium-Bromide Absorption Cycle Heat Pumps

    Vinther, Kasper; Just Nielsen, Rene; Nielsen, Kirsten Mølgaard; Andersen, Palle; Pedersen, Tom Søndergård; Bendtsen, Jan Dimon

    In this paper, we investigate the coefficient of performance (COP) of a LiBr absorption cycle heat pump under different operating conditions. The investigation is carried out using a dynamical model fitted against data recorded from an actual heat pump used for district heating in S⊘nderborg, Den......In this paper, we investigate the coefficient of performance (COP) of a LiBr absorption cycle heat pump under different operating conditions. The investigation is carried out using a dynamical model fitted against data recorded from an actual heat pump used for district heating in S...

  12. From mine to refrigeration: a life cycle inventory analysis of the production of HFC-134a

    A life cycle inventory analysis has been conducted for the production of HFC-134a (1,1,1,2-tetrafluoroethane, CH2FCF3) through from basic raw materials (crude oil, natural gas, sulphur and fluorspar) to the pure product delivered to industrial customers. The analysis was based on real industrial operations in Japan, USA and UK. It showed that production required limestone, water and transition metal catalysts, in addition to the basic raw materials, and that the energy required to provide these raw materials in a form that can be used at the plants and to process them through intermediates into HFC-134a is the equivalent of 4.52 tonnes of CO2 per tonne of product. Environmental releases associated with HFC-134a included waste salt brine (to the sea), mine tailings (mainly 'country' rock landfilled at the mine) and small quantities of calcium sulphate and spent catalyst (both sent to landfill). In addition, greenhouse gases amounting to the equivalent of 2.1 tonnes of CO2 per tonne of product were emitted to the atmosphere from the plants studied, an effect very much smaller than that estimated in previous studies mainly because the real release rates from current processes are very much less than those assumed in prior work. The global warming potential of HFC-134a is 1300, meaning that, during the first 100 years following the release of one tonne, the effect on climate change is equivalent to 1300 tonnes of carbon dioxide. Consequently, the 6.6 tonnes of carbon dioxide equivalent, emitted during production in the form of energy required and other greenhouse gases, is of relatively little importance and the key requirement to reduce environmental impact is containment during use. (Author)

  13. Experimental investigation of the discharge valve dynamics in a reciprocating compressor for trans-critical CO2 refrigeration cycle

    The self-acting valve has a significant influence on the efficiency and reliability of the reciprocating compressor. In the trans-critical CO2 cycle, the large density and high pressure difference across the valve cause serious bending and impact stresses in the valve, offering great challenges for successful valve design. Experimental investigation of the valve dynamics is required in order to design a self-acting valve with a high efficiency and long life span for the trans-critical CO2 compressor. A semi-hermetic reciprocating compressor was developed for application in CO2 refrigeration, and a test system was incorporated into the compressor performance test rig, with a focus on investigating the dynamics of the discharge valves. With the experimental results, the movement of the valve was discussed in detail for the trans-critical CO2 compressor, allowing for the study of the thermodynamic performance of the compressor. While varying design parameters such as pressure ratio, valve lift, spring stiffness and compressor speed, the movement of the discharge valve in the reciprocating CO2 compressor was measured in order to investigate the major factors that influence the valve dynamics. The average valve speed increased from 0.71 m/s to 0.81 m/s as the discharge pressure changed from 7.8 MPa to 12 MPa. The experimental methods and results discussed in this paper could provide useful information for both valve testing and the optimization of their reliability in trans-critical CO2 compressors.

  14. Experimental Study of Ambient Air Temperature Effects on The Performance of a General Vapor-Compression Refrigeration Cycle

    Ayad T. Mustafa

    2013-05-01

    Full Text Available         In this work an experimental study for the vapor – compression refrigeration cycle has been performed under temperature range of  9.7-32°C. The effect of      varying temperature on heat exchangers pressures, cooling capacity, net power consumption, and coefficient of performance COP are studied .                                   The results indicated that condenser pressure, evaporator pressure, and power consumption increased with the increase of temperature. The data also indicated that cooling capacity increased as temperature increased until 15.6°C then after it decreased with further temperature increase. Also COP follow the same tread of cooling capacity.                                                                                                              

  15. Dynamic Simulation of Household Refrigerators: Numerical Model and Experimental Comparison

    Ablanque, Nicolas; Oliet, Carles; Rigola, Joaquim; Lehmkuhl, Oriol; Oliva, Assensi

    2014-01-01

    This work presents a dynamic model to simulate a whole household refrigeration unit taking into account both the refrigeration cycle itself and the refrigerated compartments network. The methodology implemented to achieve the transient simulation of the whole system combines a steady-state approach for the refrigerating cycle loop with a transient approach for the refrigerated compartments loop. Both loops are solved at each time step (the linking boundary conditions for the refrigerating cyc...

  16. Magnetic Refrigeration and the Magnetocaloric Effect

    Petersen, Thomas Frank; Pryds, Nini; Smith, Anders;

    2006-01-01

    Magnetic refrigeration at room temperature is an emerging technology for refrigeration, which promises low energy consumption and is environmentalle friendly. Magnetic refrigeration is based on the magnetocaloric effect, which manifests itself as a reversibel increase in temperature when magnetic...... material are plased in a magnetic field. This paper introduces and describes magnetic refrigeration cycles and the magnetocaloric effect, and shows how magnetic refrigeration can be an alternative to vapour-compression refrigeration,. A review of the Danish research on magnetic refrigeration at Risø...

  17. Design and inspect of mix refrigerants used in three-stage auto-cascade refrigeration cycle%三级自动复叠系统混合工质配比设计与验证

    赵向阁; 时阳

    2011-01-01

    为了确定应用于三级自动复叠系统的混合工质,说明了混合工质组分确定的方法,并据此为一台设备选取了R134a/R23/R14/R50作为制冷剂.通过提出了一些理想状态假设之后,简化制冷剂在制冷系统中的循环过程.忽视非必须制冷R50对系统的影响,认为系统中只有R134a/R23/R14进行制冷循环.利用串联热平衡法计算了各组分的循环流量,以R14的循环量作为对比单位,与实验得出的最佳配比进行比较.通过分析误差原因,指出了在实际设备制造过程中根据计算结果确定混合工质配比的可行性.%In order to select the mix refrigeration used in three-stage auto-cascade system, some notes were pointed out for choosing the component, R134a/R23/R14/R50 were chosen as a mix for the equipment. After simplifying the refrigeration cycle process in the system and giving out some suppose in ideal,R50 was ignored for not necessary and it was considered that there was only R134a/R23/R14 in the cycle.Each component cycle flow in the cycle was calculated with series heat balance method and compared with the best component ratio,which was suggested according to experiment result with the flow quantity of R14 as a unit. After analyzing the reason which caused the error,the feasibility was pointed out for selecting the mixture refrigerant component ratio in actual device manufacturing process by calculating.

  18. Thermodynamic Analysis on Sub-cooling Process in CO2 Trans-critical Refrigeration Cycle%二氧化碳跨临界制冷循环过冷却过程热力学分析

    邓帅; 王如竹; 代彦军

    2013-01-01

    The feasibility of applying the sub-cooling technology to the CO2 trans-critical cycle was discussed, and the performance of new cycle was analyzed as well. Particularly, sub-cooling conversed from solar thermal energy was analyzed through simulation for possible applications. The calculation results show that cooling COP of the cycle reached to 4.00 and can be increased by 45.0%when temperature difference of sub-cooling is 5℃ in summer. While sub-cooling is realized by a solar-driven absorption refrigeration cycle and the driving temperature is 94℃, the assisted cooling capacity transformed from regenerative energy reached to 33%of the total cooling capacity. The difference in the sub-cooling process between conventional refrigerants subcritical cycle and CO2 trans-critical cycle was also discussed briefly.%本文探讨了过冷却技术应用于二氧化碳跨临界制冷循环的可行性,并对更新后的循环进行了性能分析,特别对太阳能应用于过冷却过程进行了模拟分析,最后通过现场实验对性能提升效果进行了验证。理论循环计算显示夏季5℃过冷可使循环COP达到4.00,制冷性能提升45%;当使用太阳能驱动的吸收式制冷循环产生过冷时,驱动温度为94℃时,可再生能源转化的辅助制冷量占总制冷量的比例可达33%。过冷热力过程在二氧化碳跨临界制冷循环中与在常规制冷剂亚临界制冷循环中有所不同,故本文对这种异同进行了适当的讨论。

  19. Ionic Refrigerator

    Richter, R.

    1984-01-01

    With no moving parts, proposed refrigerator has long life. Thermal energy of refrigeration process transported by hydrogen ions that go through three phase changes in absorbing heat and three phase changes in dissipating heat.

  20. The Weak and Strong Oblique Shock Waves Appeared on the Carbon Dioxide Two-phase Flow in the Ejector Refrigeration Cycle

    After the Great East Japan Earthquake, the saving energy became the one of the most important issues. Especially, saving the electrical power for air-conditioning at summer time is a problem of great urgency. We have been developing the ejector refrigeration system which can improve coefficient of performance of refrigeration systems by converting exhausted expansion energy into useful pressure energy. The performance of the ejector is greatly affected by the pressure recovery at the mixing section in the ejector. It is elucidated by our recent research on the carbon dioxide refrigeration cycle that the pressure recovery at the ejector is performed by oblique shock waves appeared in the mixing section. The purpose of this research is to clarify the characteristics of the two-phase flow oblique shock waves in the supersonic carbon dioxide two-phase flow. It is shown by the theoretical analyses that the two types of oblique shock waves occur on the supersonic two-phase flow. One is the week shock wave behind of which the flow is still a subsonic state. The other is the strong oblique shock wave which has a large pressure recovery. And the experimental research also carried out by using the carbon dioxide two-phase flow channel. The theoretical results are compared with the experiment.

  1. Study on Jet-Compression Hybrid Refrigeration Cycle Driven by Heat and Power%热-电驱动喷射压缩复合制冷循环特性研究

    王林; 谈莹莹; 梁坤峰; 安方涛; 陈宁

    2014-01-01

    Autocascade refrigeration can achieve lower refrigeration temperature easily,but it totally consumes high grade energy and its COP is low.Jet refrigeration can achieve the refrigeration effect by utilizing low grade heat sources.However,its refrigeration temperature is high.In order to utilize low grade heat to the domain of cryogenic freezing,jet/compression hybrid refrigeration cycle with mixed refrigerants driven by low grade heat and power was presented.The new cycle contributes to improving the efficiency of refrigeration significantly and achieving lower refrigeration temperature.On a basis of its mathematical model,the influences of compression ratio of the ejector and compressor on mechanical and thermal coefficient of performance(COPme/COPth) were analyzed.The results indicate that refrigeration efficiency of the hybrid refrigeration cycle is much higher than that of the traditional autocascade refrigeration cycle.%自复叠制冷循环具有获得制冷温度低优点,但其完全消耗的是高品位电能或机械能;喷射制冷具有利用低品位低温热源(60~100℃)制取冷量、且制冷温度较高时制冷效率高等优点,但难以获得较低制冷温度.因此,为了实现低品位热在低温冷冻领域高效利用并节省高品位电能,本文提出一种由低品位低温热源与电能联合驱动的混合工质喷射/压缩复合制冷循环.建立组成新循环各部件热力学数学模型,分析喷射器压缩比和压缩机压缩比对复合式制冷循环的热性能系数和机械性能系数影响,并与传统的自复叠制冷循环特性进行比较分析.研究表明,低品位热源与电能联合驱动喷射/压缩复合制冷循环较传统自复叠制冷循环可显著提高制冷效率并获得更低制冷温度.

  2. Evaluation Analysis of the CO2 Emission and Absorption Life Cycle for Precast Concrete in Korea

    Taehyoung Kim

    2016-07-01

    Full Text Available To comply with recent international trends and initiatives, and in order to help achieve sustainable development, Korea has established a greenhouse gas (GHG emission reduction target of 37% (851 million tons of the business as usual (BAU rate by 2030. Regarding environmentally-oriented standards such as the IGCC (International Green Construction Code, there are also rising demands for the assessment on CO2 emissions during the life cycle in accordance with ISO (International Standardization Organization’s Standard 14040. At present, precast concrete (PC engineering-related studies primarily cover structural and construction aspects, including improvement of structural performance in the joint, introduction of pre-stressed concrete and development of half PC. In the manufacture of PC, steam curing is mostly used for the early-strength development of concrete. In steam curing, a large amount of CO2 is produced, causing an environmental problem. Therefore, this study proposes a method to assess CO2 emissions (including absorption throughout the PC life cycle by using a life cycle assessment (LCA method. Using the proposed assessment method, CO2 emissions during the life cycle of a precast concrete girder (PCG were assessed. In addition, CO2 absorption was assessed against a PCG using conventional carbonation and CO2 absorption-related models. As a result, the CO2 emissions throughout the life cycle of the PCG were 1365.6 (kg-CO2/1 PCG. The CO2 emissions during the production of raw materials among the CO2 emissions throughout the life cycle of the PCG were 1390 (kg-CO2/1 PCG, accounting for a high portion to total CO2 emissions (nearly 90%. In contrast, the transportation and manufacture stages were 1% and 10%, respectively, having little effect on total CO2 emissions. Among the use of the PCG, CO2 absorption was mostly decided by the CO2 diffusion coefficient and the amount of CO2 absorption by cement paste. The CO2 absorption by carbonation

  3. Magnetic refrigerator for hydrogen liquefaction

    Matsumoto, K; Kondo, T [Department of Physics, Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan); Yoshioka, S; Kamiya, K; Numazawa, T [Tsukuba Magnet Laboratory, National Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0003 (Japan)], E-mail: kmatsu@kenroku.kanazawa-u.ac.jp

    2009-02-01

    Magnetic refrigeration which is based on the magnetocaloric effect of solids has the potential to achieve high thermal efficiency for hydrogen liquefaction. We have been developing a magnetic refrigerator for hydrogen liquefaction which cools down hydrogen gas from liquid natural gas temperature and liquefies at 20 K. The magnetic liquefaction system consists of two magnetic refrigerators: Carnot magnetic refrigerator (CMR) and active magnetic regenerator (AMR) device. CMR with Carnot cycle succeeded in liquefying hydrogen at 20K. Above liquefaction temperature, a regenerative refrigeration cycle should be necessary to precool hydrogen gas, because adiabatic temperature change of magnetic material is reduced due to a large lattice specific heat of magnetic materials. We have tested an AMR device as the precooling stage. It was confirmed for the first time that AMR cycle worked around 20 K.

  4. Magnetic refrigerator for hydrogen liquefaction

    Magnetic refrigeration which is based on the magnetocaloric effect of solids has the potential to achieve high thermal efficiency for hydrogen liquefaction. We have been developing a magnetic refrigerator for hydrogen liquefaction which cools down hydrogen gas from liquid natural gas temperature and liquefies at 20 K. The magnetic liquefaction system consists of two magnetic refrigerators: Carnot magnetic refrigerator (CMR) and active magnetic regenerator (AMR) device. CMR with Carnot cycle succeeded in liquefying hydrogen at 20K. Above liquefaction temperature, a regenerative refrigeration cycle should be necessary to precool hydrogen gas, because adiabatic temperature change of magnetic material is reduced due to a large lattice specific heat of magnetic materials. We have tested an AMR device as the precooling stage. It was confirmed for the first time that AMR cycle worked around 20 K.

  5. Lubricating oil distribution and flow states in a CO2 refrigeration cycle in transcritical operation; Schmieroelverteilung und Stroemungszustaende in einem CO2-Kaeltekreislauf bei transkritischer Betriebsweise

    Marckmann, H.; Eggers, R. [Technische Univ. Hamburg-Harburg, Hamburg, Arbeitsbereich Verfahrenstechnik II Waerme- und Stofftransport (Germany); Fahl, J. [Fuchs Europe Schmierstoffe GmbH, Hamburg (Germany)

    2003-07-01

    Based on equilibrium data for mutual solubility of CO2 and refrigerator oil, the design and operation of an experimental CO2 refrigerator were investigated with the intention of establishing material and energy balances by means of sampling and mixture analyses. For investigating two-phase flow states, a high-pressure visual inspection cell was installed at various places of the CO2 cycle. Together with the measurement of relevant temperatures and mass flows, an analysis of the oil distribution in the cycle is now possible. [German] Ausgehend von Gleichgewichtsdaten fuer die gegenseitige Loeslichkeit im System ''CO{sub 2}-Kaeltemaschinenoel'' sind der Aufbau und der Betrieb einer CO{sub 2}-Versuchskaelteanlage mit der Zielsetzung vorgenommen worden, im Kreislauf durch Probenahmestellen und Gemischanalysen Stoff- und Energiebilanzen aufstellen zu koennen. Zur Beurteilung von zweiphasigen Stroemungszustaenden ist eine Hochdrucksichtzelle an verschiedenen Orten des CO{sub 2}-Kreislaufes installiert worden. Gemeinsam mit der Ermittlung relevanter Temperaturen und Massenstroeme ist eine Analyse ueber die Oelverteilung im Kreislauf moeglich. (orig.)

  6. NLP model of a LiBr–H2O absorption refrigeration system for the minimization of the annual operating cost

    In this paper the optimization of a LiBr–H2O absorption refrigeration system with the annual operating cost as the objective function to be minimized is presented. The optimization problem is established as a Non-Linear Programming (NLP) model allowing a formulation of the problem in a simple and structured way, and reducing the typical complexity of the thermal systems. The model is composed of three main parts: the thermodynamic model based on the exergy concept including also the proper formulation for the thermodynamic properties of the LiBr–H2O mixture, the second is the economic model and the third part composed by inequality constraints. The solution of the model is obtained using the CONOPT solver suitable for NLP problems (code is available on request). The results show the values of the decision variables that minimize the annual cost under the set of assumptions considered in the model and agree well with those reported in other works using different optimization approaches. - Highlights: ► The optimization of an ARS is presented using the annual operating cost as the objective function. ► The problem is established as an NLP model allowing a formulation in a simple and structured way. ► Several formulations for the thermodynamic properties were tested to implement the simpler ones. ► The results obtained agree well with those reported in the work being in comparison.

  7. Determination of a Vapor Compression Refrigeration System Refrigerant Charge

    YangChun-Xin; DangChao-Bin

    1995-01-01

    A physical model is established in this paper to describe the heat transfer and two phase flow of a refrigerant in the evaporator and condenser of a vapor compression refrigeration system.The model in then used to determine the refrigerant charge in vapor compression units.The model is used for a sensitivity analysis to determine the effect that varing design parameters on the refrigerant charge,The model is also used to evaluate the effect of refrigerant charge and the thermal physical properties on the refrigeration cycle,The predicted value of the refigerant charge and experimental data agree well The model and the method presented in this paper could be used to design vapour compression units such as domestic refrigeratirs and air conditioners.

  8. A new approach to thermodynamic analysis of ejector-absorption cycle: artificial neural networks

    Thermodynamic analysis of absorption thermal systems is too complex because of analytic functions calculating the thermodynamic properties of fluid couples involving the solution of complex differential equations. To simplify this complex process, the use of artificial neural networks (ANNs) has been proposed for the analysis of ejector-absorption refrigeration systems (EARSs). ANNs approach was used to determine the properties of liquid and two phase boiling and condensing of an alternative working fluid couple (methanol/LiBr), which does not cause ozone depletion for EARS. The back-propagation learning algorithm with three different variants and logistic sigmoid transfer function was used in the network. In addition, this paper presents a comparative performance study of the EARS using both analytic functions and prediction of ANN for properties of the fluid couple. After training, it was found that average error is less than 1.3% and R2 values are about 0.9999. Additionally, when the results of analytic equations obtained by using experimental data and by means of ANN were compared, deviations in coefficient of performance (COP), exergetic coefficient of performance (ECOP) and circulation ratio (F) for all working temperatures were found to be less than 1.8%, 4%, 0.2%, respectively. Deviations for COP, ECOP and F at a generator temperature of ∼90 deg. C for which the COP of the system is maximum are 1%, 2%, 0.1%, respectively, for other working temperatures. As seen from the results obtained, the calculated thermodynamic properties are obviously within acceptable uncertainties

  9. 新型双重热化学吸附制冷热力循环研究%Study on an Innovative Combined Double-Way Thermochemical Sorption Refrigeration Cycle

    李廷贤; 王如竹; 陈恒; 王丽伟

    2011-01-01

    本文提出了一种全新的基于吸附-再吸附技术的双重热化学吸附制冷热力循环.实验研究表明该新型双重热化学吸附制冷热力循环用于制冷空调领域是完全可行的,在每次循环过程中仅从外界热源输入一次高温解吸热,就可以实现吸附制冷和再吸附制冷两次制冷过程;相对传统热化学再吸附制冷循环和吸附制冷循环,双重热化学吸附制冷热力循环可显著提高吸附制冷系统的工作性能,在相同制冷剂循环量下,双重热化学吸附制冷循环可将制冷系数COPi分别提高60%和167%.%In this paper, an innovative combined double-way thermochemical sorption refrigeration cycle based on adsorption and resorption processes is proposed. Experimental results showed that the presented combined double-way sorption cycle is feasible for refrigeration application, and two cold productions (adsorption refrigeration and resorption refrigeration) can be obtained during one cycle at the expense of only one heat input from an external heat source. In comparison with conventional thermochemical resorption cycle or adsorption cycle, the double-way sorption cycle has a distinct advantage of higher Coefficient of Performance (COP). At the same cycled mass of refrigerant, the ideal COP can be improved by 60% and 167% when compared with conventional resorption cycle and adsorption cycle, respectively.

  10. Performance Evaluation of a Lithium-Chloride Absorption Refrigeration and an Assessment of Its Suitability for Biomass Waste Heat

    Sacha Oberweis

    2012-10-01

    Full Text Available This paper presents a computer model that will evaluate the performance of a thermo-chemical accumulator. The model is based on operational data such as temperatures and flow rates. The ultimate goal for this model is to estimate the coefficient of performance (COP of this unit when run on hot water from biomass combustion as the heat source. The outputs of the model are verified by comparing the simulation of the actual machine with published experimental data. The computed results for cooling COP are within 10% of the measured data. The simulations are all run for heat load temperatures varying between 80 °C and 110 °C. As expected, simulation results showed an increase in COP with increased heat source temperatures. The results demonstrate that the potential of combined solar and biomass combustion as a heat source for absorption cooling/heating in climates with low solar radiation can be coupled with biomass waste.

  11. Thermodynamic modeling and performance analysis of the variable-temperature heat reservoir absorption heat pump cycle

    Qin, Xiaoyong; Chen, Lingen; Ge, Yanlin; Sun, Fengrui

    2015-10-01

    For practical absorption heat pump (AHP) plants, not all external heat reservoir heat capacities are infinite. External heat reservoir heat capacity should be an effect factor in modeling and performance analysis of AHP cycles. A variable-temperature heat reservoir AHP cycle is modeled, in which internal working substance is working in four temperature levels and all irreversibility factors are considered. The irreversibility includes heat transfer irreversibility, internal dissipation irreversibility and heat leakage irreversibility. The general equations among coefficient of performance (COP), heating load and some key characteristic parameters are obtained. The general and optimal characteristics are obtained by using numerical calculations. Besides, the influences of heat capacities of heat reservoirs, internal dissipation irreversibility, and heat leakage irreversibility on cycle performance are analyzed. The conclusions can offer some guidelines for design and operation of AHP plants.

  12. Conception and simulation of an improved solar refrigeration unit

    If the solar energy possesses the advantage to be clean, free and new able, this last is probably, considered like an adapted potential solution, that answers in even time at a economic preoccupation and ecological problems. Among the main done currently research is the use of free source to make operate system of refrigeration. following a bibliographic study on the absorption cycles, the utilized couples absorbents-refrigerating fluids and the capture of the solar energy, an unit refrigeration using an improved solar absorption cycle of ammonia has been conceived and studied. The simulation results in permanent regime concerned the determination of the variation of the performance criteria mainly according to the operatives kept for this study. The obtained results showed, that the improved mono pressure absorption cycle of ammonia is suitable well for the cold production by means of the solar energy and that with a simple plate collector we can reach a power, of the order of 900 watts sufficient for domestic use.(Author)

  13. 太阳能单效溴化锂吸收式制冷空调技术研究现状%Research Status of Solar Single-effect Lithium Bromide Absorption Refrigeration and Air Conditioning Technology

    周兴法; 谢应明; 谢振兴

    2014-01-01

    In view of the solar single-effect lithium bromide absorption refrigeration and air conditioning technology , which is used mostly in solar refrigeration technology at present , the solar collectors that are available for solar refrigeration are introduced in detail,large amounts of the cases of experimental study and simulation analysis are enumerated ,and finally a novel solar refrige-ration system with bubble pump is presented .Because of its several advantages such as quiet , small volume, energy conserva-tion,and cooling heat recovery ,it is an important development direction of solar absorption refrigeration system in terms of minia-turization.%针对目前太阳能制冷技术中应用最多的太阳能单效溴化锂吸收式制冷空调技术,介绍各种可用于太阳能制冷空调的集热器,列举大量的太阳能单效溴化锂吸收式制冷空调系统的试验研究和模拟分析的案例,最后提出一个新型太阳能无泵溴化锂吸收式制冷空调系统。该系统具有运行安静、体积小、节能、可回收冷却热等优点,是太阳能吸收式制冷系统小型化的一个重要发展方向。

  14. Magnetic refrigeration: Materials, design, and applications. (Latest citations from the INSPEC: Information services for the Physics and Engineering Communities database). Published Search

    The bibliography contains citations concerning cryogenics using magnetic refrigerants. Refrigerant properties, magnetic materials, and thermal characteristics are discussed. Magnetic refrigerators are used for helium liquefaction, cooling superconductors, and superfluid helium production. Carnot-cycle refrigerators, reciprocating refrigerators, parasitic refrigerators, Ericsson refrigerators, and Stirling cycle refrigerators are among the types of magnetic refrigerators evaluated. (Contains a minimum of 94 citations and includes a subject term index and title list.)

  15. Available energy analysis of new tandem double-capillary tube refrigeration system for refrigerator-freezers

    Maogang HE; Xinzhou SONG; Ying ZHANG; Jiantao ZHANG

    2008-01-01

    A new tandem double-capillary tube refri-geration system for refrigerator-freezers is proposed. A capillary tube was added between the two evaporators in the fresh and frozen food storage chests to raise the evaporation temperature of the refrigerating chamber, and reduce the heat exchange temperature difference and the available energy loss. Peng-Robinson (P-R) equation of state was adopted to calculate the thermodynamic properties of the refrigerants, and the available energy analysis of the vapor compression refrigeration cycle was programmed to calculate the thermodynamic perfor-mances of the new and the conventional refrigeration cycle of the refrigerator-freezer. The calculation results show that the available energy efficiency of the conven-tional refrigeration cycle of the refrigerator-freezer is 21.20% and 20.57%, respectively when the refrigerant is R12 and R134a, while that of the double-capillary tube refrigeration cycle of the refrigerator-freezer is 23.97% and 23.44%, respectively. By comparison, the available energy efficiency of the new refrigeration system increases by 13.07% and 13.95%, respectively.

  16. High Efficiency Refrigeration Process Project

    National Aeronautics and Space Administration — A refrigeration cycle is proposed for development which can reduce compressor work and increase cooling effect, by eliminating a portion of the irreversabilities...

  17. Experimental evaluation of an Internal Heat Exchanger in a CO2 subcritical refrigeration cycle with gas-cooler

    Llopis Doménech, Rodrigo; Sanz Kock, Carlos; Cabello López, Ramón; Sánchez García-Vacas, Daniel; Torrella Alcaraz, Enrique

    2015-01-01

    We present the experimental evaluation of an internal heat exchanger or suction-line/liquid-line heat exchanger in a CO2 subcritical refrigeration plant with gas-cooler. The plant, driven by a 1.5kW CO2 semi hermetic compressor, uses brazed plate heat exchangers as condenser, evaporator and internal heat exchanger, an air finned tube gas-cooler and an electronic expansion valves. The evaluation (77 steady- states) covers evaporating temperatures from -40 to -25 oC and condensing temperatures ...

  18. Recent Advances in SRS on Hydrogen Isotope Separation Using Thermal Cycling Absorption Process

    The recent Thermal Cycling Absorption Process (TCAP) advances at Savannah River Site (SRS) include compressor-free concept for heating/cooling, push and pull separation using an active inverse column, and compact column design. The new developments allow significantly higher throughput and better reliability from 1/10th of the current production system's footprint while consuming 60% less energy. Various versions are derived in the meantime for external customers to be used in fusion energy projects and medical isotope production

  19. High Performance Cascading Adsorption Refrigeration Cycle with Internal Heat Recovery Driven by a Low Grade Heat Source Temperature

    Yuki Ueda; Atsushi Akisawa; Aep Saepul Uyun; Takahiko Miyazaki

    2009-01-01

    This paper presents the performance of an advanced cascading adsorption cycle that utilizes a driven heat source temperature between 90–130 ºC. The cycle consists of four beds that contain silica gel as an adsorber fill. Two of the beds work in a single stage cycle that is driven by an external heat source, while the other two beds work in a mass recovery cycle that is driven by waste heat of sensible and adsorption heat of the high temperature cycle. The performances, in terms of the coef...

  20. Performance Analysis of CO2 Transcritical Compression Cycle and Freon Refrigeration Cycle%CO2跨临界循环和氟利昂制冷剂循环性能分析

    曾宪阳; 王洪利; 马一太

    2011-01-01

    Based on refrigerants R134a, R290 and CO2, the performance comparison of three kinds of single stage compression cycle and two stage cycle were employed.The results shows that the performances COP of all cycles are gradually increased with the evaporation temperature and compressor efficiency increasing, and the single stage CO2 transcritical cycle has an optimal discharge pressure.Replace the throttle with an expander can significantly improve the system coefficient of performance of CO2 transcritical cycle.The low stage compressor efficiency has an important effect on the performance of two stage compression cycle than the high stage compressor efficiency and the CO2 transcritical cycle has a higher optimal intermediate pressure than other cycles.Some fundamental data were obtained for improving cycle performance and developing the CO2 refrigeration air-conditioning and heat pump water heater products.%本文以R134a、R290和CO2制冷剂为研究对象,分别对三种单、双级循环的性能进行对比.结果表明,随蒸发温度增加、压缩机效率升高和冷凝器出口温度降低,所有循环性能均提高,单级CO2循环存在最优排气压力;用膨胀机代替节流阀可以显著提高CO2跨临界循环COP;低压级压缩机的效率比高压级压缩机对系统性能影响明显.双级循环中,CO2循环最优中间压力远高于其它两种循环.本研究为高效、节能的空调和热泵产品开发提供基础资料.

  1. A Gd{sub x}Ho{sub 1−x}-based composite and its performance characteristics in a regenerative Ericsson refrigeration cycle

    Xu, Z.C.; Lin, G.X., E-mail: gxlin@xmu.edu.cn; Chen, J.C.

    2015-08-05

    Highlights: • MCE characteristics of Gd{sub x}Ho{sub 1−x} alloys with different x are determined. • A promising material compositing with Gd{sub x}Ho{sub 1−x} alloys is suggested. • Optimal mass ratios of three components in the composite are obtained. • Isothermal magnetic entropy change of the composite is close to a constant inside 28 K. • Thermodynamic performances between Gd{sub x}Ho{sub 1−x} alloys and the composite are compared. - Abstract: Based on the molecular field theory, de Gennes factor model, and numerical calculation method, the magnetic entropy change and Curie temperature of Gd{sub x}Ho{sub 1−x} alloys are studied, where x = 0.80, 0.91, and 1. The composite magnetic material consists of Gd{sub 0.80}Ho{sub 0.20}, Gd{sub 0.91}Ho{sub 0.09}, and Gd, according to the definite mass ratios y{sub 1}, y{sub 2} and y{sub 3}. The calculation results show that there exist optimal mass ratios y{sub 1opt}, y{sub 2opt}, and y{sub 3opt} and their values depend on the applied magnetic field μ{sub 0}H{sub 1}. When μ{sub 0}H{sub 1} = 2 T, y{sub 1opt}, y{sub 2opt}, and y{sub 3opt} are equal to 0.24, 0.17, and 0.59, respectively. It is found that the total magnetic entropy change of the composite magnetic material 0.24Gd{sub 0.80}Ho{sub 0.20}⋅0.17Gd{sub 0.91}Ho{sub 0.09}⋅0.59Gd under 2 T applied magnetic field change is close to a constant in the region between 265 K and 293 K. Furthermore, the regenerative Ericsson refrigeration cycle using the composite magnetic material as the working substance is put forward and its cyclic performances including the net cooling quantity Q{sub net}, coefficient of performance (COP), etc. are analyzed. The results obtained show that for the regenerative Ericsson refrigeration cycle using the composite magnetic material as the working substance, there are not only a large temperature span (28 K) but also a large net cooling quantity (1008 J/kg under 2 T applied magnetic field) and a large COP (9.01), which are

  2. High Performance Cascading Adsorption Refrigeration Cycle with Internal Heat Recovery Driven by a Low Grade Heat Source Temperature

    Yuki Ueda

    2009-11-01

    Full Text Available This paper presents the performance of an advanced cascading adsorption cycle that utilizes a driven heat source temperature between 90–130 ºC. The cycle consists of four beds that contain silica gel as an adsorber fill. Two of the beds work in a single stage cycle that is driven by an external heat source, while the other two beds work in a mass recovery cycle that is driven by waste heat of sensible and adsorption heat of the high temperature cycle. The performances, in terms of the coefficient of performance (COP and the specific cooling power (SCP, are compared with conventional cascading-without-mass-recovery and single-stage cycles. The paper also presents the effect of the adsorbent mass on performance. The results show that the proposed cycle with mass recovery produces as high of a COP as the COP that is produced by the conventional cascading cycle. However, it produces a lower SCP than that of the single-stage cycle.

  3. Simulated performance of biomass gasification based combined power and refrigeration plant for community scale application

    Chattopadhyay, S.; Mondal, P.; Ghosh, S.

    2016-07-01

    Thermal performance analysis and sizing of a biomass gasification based combined power and refrigeration plant (CPR) is reported in this study. The plant is capable of producing 100 kWe of electrical output while simultaneously producing a refrigeration effect, varying from 28-68 ton of refrigeration (TR). The topping gas turbine cycle is an indirectly heated all-air cycle. A combustor heat exchanger duplex (CHX) unit burns producer gas and transfer heat to air. This arrangement avoids complex gas cleaning requirements for the biomass-derived producer gas. The exhaust air of the topping GT is utilized to run a bottoming ammonia absorption refrigeration (AAR) cycle via a heat recovery steam generator (HRSG), steam produced in the HRSG supplying heat to the generator of the refrigeration cycle. Effects of major operating parameters like topping cycle pressure ratio (rp) and turbine inlet temperature (TIT) on the energetic performance of the plant are studied. Energetic performance of the plant is evaluated via energy efficiency, required biomass consumption and fuel energy savings ratio (FESR). The FESR calculation method is significant for indicating the savings in fuel of a combined power and process heat plant instead of separate plants for power and process heat. The study reveals that, topping cycle attains maximum power efficiency of 30%in pressure ratio range of 8-10. Up to a certain value of pressure ratio the required air flow rate through the GT unit decreases with increase in pressure ratio and then increases with further increase in pressure ratio. The capacity of refrigeration of the AAR unit initially decreases up to a certain value of topping GT cycle pressure ratio and then increases with further increase in pressure ratio. The FESR is found to be maximized at a pressure ratio of 9 (when TIT=1100°C), the maximum value being 53%. The FESR is higher for higher TIT. The heat exchanger sizing is also influenced by the topping cycle pressure ratio and GT-TIT.

  4. Thermoeconomic evaluation of CO2 alkali absorption system applied to semi-closed gas turbine combined cycle

    A new carbon dioxide separation system based on CO2 absorption in aqueous solutions of alkaline salts (sodium and potassium carbonate) was studied with reference to semi-closed gas turbine/combined cycle (SCGT/CC), and compared to results obtained with existing technologies. Use of calcium hydroxide for the regeneration of the exhaust solution was studied in order to obtain a tail-end product, calcium carbonate in the form of precipitated calcium carbonate (PCC) with a wide spread and continuously growing market. The alkali CO2 absorption process was compared with a conventional amine absorption process (DEA+MDEA), referring to the same SCGT/CC based on the same CO2 removal efficiency. The comparison allows foregrounding of the possible goals of the CO2 alkali absorption process with respect to previous amine cycle analyses. The modeling approach focuses on a thermodynamical and economical first comparison of the proposed cycle to previous studies carried out on CO2 absorption (Energy Convers. Manage. 40 (1999) 1917; Absorption of CO2 with amines in a semi closed GT cycle: plant performance and operating costs, ASME Paper 98-GT-395, American Society of Mechanical Engineers ASME Publishing, New York, 1998; Greenhouse Gas Control Technologies Conference, Interlaken, Switzerland, Pergamon, Oxford, 1999)

  5. Thermodynamic analysis of transcritical CO2 refrigeration cycle with different expansion device%采用不同膨胀机构的跨临界CO2循环性能分析

    马娟丽; 刘昌海; 侯予

    2012-01-01

    运用热力学第一定律和第二定律对跨临界CO2基本循环、膨胀机循环、喷射器循环和涡流管循环进行了分析,计算了各循环各个部件的(火用)损失,比较了各循环性能系数和总(火用)损失.计算结果表明,采用膨胀机、喷射器和涡流管等膨胀设备代替基本循环中的节流阀后,由于这些改进膨胀设备的(火用)损失小于基本循环节流阀的(火用)损失,同时改进循环中压缩机的(火用)损失小于基本循环的压缩机(火用)损失,从而减小了循环总(火用)损失,提高了循环的COP.膨胀机循环的COP远大于其它跨临界CO2循环,其次为喷射器循环和涡流管循环.%A comparative study on transcritical carbon dioxide refrigeration cycle respectively with throttling valve,expander,ejector and vortex tube was performed by the first and second laws of thermodynamics in theory. And these cycles' COP and exergy losses were investigated. It is found that the exergy loss of other expansion devices is less than the exergy loss of throttling valve. The exergy loss of compressor in transcritical carbon dioxide refrigeration cycle with other expansion devices is less than the exergy loss of compressor in transcritical carbon dioxide refrigeration cycle with throttling valve. Thus the total exergy loss of these cycles with other expansion devices is less than the total exergy loss of cycle with throttling valve, and the COP of these cycles with other expansion devices is higher than the COP of cycle with throttling valve. The COP of transcritical carbon dioxide refrigeration cycle with expander is much higher than that of other cycles, then transcritical carbon dioxide refrigeration cycle with ejector and with vortex tube.

  6. 两次节流循环在氨制冷系统的效率分析%Efficiency analysis on the cycle with flash intercooler in ammonia refrigeration system

    张建一; 陈海洋

    2012-01-01

    his paper analyzed the two - stage compression refrigeration cycle with different intercoolers. The refrigeration coefficients of cycles with shell - and - coil intercooler and flash intercooler were calculated based on a case of cold store. The results show that theoretical refrigeration coefficient.increased by 1.3% and the refrigeration coefficient for the case increased by 0. 7% -0.8% when shell - and - coil intercooler was replaced by Dash intercooler in two - stage compression cycle. The theoretical power consumption of refrigeration cycle with flash intercooler will decrease 5kW than that with shell - and - coil intercooler under full capacity. The initial investment cost will also reduce if flash intercooler is adopted in two - stage compression system.%文中分析不同节流方式下的两级压缩制冷循环.基于冷库实例,计算出了制冷循环在一次节流和二次节流方式下的制冷系数.结果显示,使用两次节流制冷循环,理论制冷系数提高了1.3%,冷库实例制冷系数提高了0.7%-0.8%.两次节流制冷系统在满负荷下运行时,压缩机消耗的理论功率比一次节流下降5kW.使用两次节流方式的制冷系统,在初投资费用上也有所降低.

  7. An Experimental Comparison of the Refrigerant Flow through Adiabatic and Non-Adiabatic Helical Capillary Tubes

    Javidmand, Puya; Zareh, Masoud

    2014-01-01

    Capillary tubes are used as refrigerant controlling devices, expansion devices and also as heart of a small vapor compression refrigeration cycle. It connects outlet condenser to the inlet evaporator and balances the refrigeration cycle pressure and controls the refrigerant mass flux. Capillary tubes are relatively cheap, resulting in extensive implementations in small household refrigerators and freezers with nearly constant refrigeration load. In general, the inner diameter and length of a ...

  8. Design and Optimization on Simulation System of Mine CO2 Open Loop Cycle Refrigeration%矿用CO2开放式制冷仿真系统设计与优化

    曹利波

    2013-01-01

    According to the importance of the CO2 open loop cycle refrigeration applied to the rescue cabin, the refuge chamber and other limited airtight space, the FLOWMASTER simulation software of the thermal fluid system was applied to design the simulation system of the CO2 open loop cycle refrigeration applied to a limited airtight space. Under the conditions to meet the designed refrigeration value and the pressure drop and temperature drop at the inlet and outlet of the pneumatic blower, the tube length of the evaporator was optimized and the optimum length of the evaporator was obtained. Meanwhile the refrigeration system features and the different refrigeration value under the non designed performances were checked.The test certification was conducted on the refrigeration simulation system.The simulated value and the test value were well fitted and the simulation accuracy and precision of the system were verified.%针对CO2开放式制冷在避难硐室、救生舱等有限密闭空间中应用的重要性,利用FLOWMASTER热流体计算仿真软件,设计了一种用于有限密闭空间的CO2开放式制冷仿真系统,在满足设计制冷量和气动风机进出口压降、温降的条件下,对蒸发器管长进行优化,获得了最佳蒸发器长度,同时对非设计工况下的制冷系统特性及不同制冷量进行校核,并对该制冷仿真系统进行了试验验证,仿真值与试验值吻合良好,验证了系统仿真的准确性和精确性.

  9. Analysis of Combined Power and Refrigeration Generation Using the Carbon Dioxide Thermodynamic Cycle to Recover the Waste Heat of an Internal Combustion Engine

    Shunsen Wang

    2014-01-01

    Full Text Available A novel thermodynamic system is proposed to recover the waste heat of an internal combustion engine (ICE by integrating the transcritical carbon dioxide (CO2 refrigeration cycle with the supercritical CO2 power cycle, and eight kinds of integration schemes are developed. The key parameters of the system are optimized through a genetic algorithm to achieve optimum matching with different variables and schemes, as well as the maximum net power output (Wnet. The results indicate that replacing a single-turbine scheme with a double-turbine scheme can significantly enhance the net power output (Wnet and lower the inlet pressure of the power turbine (P4. With the same exhaust parameters of ICE, the maximum Wnet of the double-turbines scheme is 40%–50% higher than that of the single-turbine scheme. Replacing a single-stage compression scheme with a double-stage compression scheme can also lower the value of P4, while it could not always significantly enhance the value of Wnet. Except for the power consumption of air conditioning, the net power output of this thermodynamic system can reach up to 13%–35% of the engine power when it is used to recover the exhaust heat of internal combustion engines.

  10. Recent advances in SRS on hydrogen isotope separation using thermal cycling absorption process

    TCAP (Thermal Cycling Absorption Process) is a gas chromatograph in principle using palladium in the column packing, but it is unique in the fact that the carrier gas, hydrogen, is being isotopically separated and the system is operated in a semi-continuous manner. TCAP units are used to purify tritium. The recent TCAP advances at Savannah River Site (SRS) include compressor-free concept for heating/cooling, push and pull separation using an active inverse column, and compact column design. The new developments allow significantly higher throughput and better reliability from 1/10 of the current production system's footprint while consuming 60% less energy. Various versions are derived in the meantime for external customers to be used in fusion energy projects

  11. Recent advances in SRS on hydrogen isotope separation using thermal cycling absorption process

    Xiao, X.; Kit Heung, L.; Sessions, H.T. [Savannah River National Laboratory - SRNL, Aiken, SC (United States)

    2015-03-15

    TCAP (Thermal Cycling Absorption Process) is a gas chromatograph in principle using palladium in the column packing, but it is unique in the fact that the carrier gas, hydrogen, is being isotopically separated and the system is operated in a semi-continuous manner. TCAP units are used to purify tritium. The recent TCAP advances at Savannah River Site (SRS) include compressor-free concept for heating/cooling, push and pull separation using an active inverse column, and compact column design. The new developments allow significantly higher throughput and better reliability from 1/10 of the current production system's footprint while consuming 60% less energy. Various versions are derived in the meantime for external customers to be used in fusion energy projects.

  12. Energy analysis of a diffusion absorption cooling system using lithium nitrate, sodium thiocyanate and water as absorbent substances and ammonia as the refrigerant

    A diffusion absorption cooling system is analyzed to determine the appropriate fluid for the unit, based on the coefficient of performance (COP) and operating conditions, by comparing lithium nitrate (LiNO3), sodium thiocyanate (NaSCN) and water (H2O) as absorbent substances and by using ammonia (NH3) as the refrigerant. The presence of crystallization in the system is analyzed as a function of the generator and absorber temperatures. Additionally, the effects on the efficiency of the system from adding the inert gas helium (He) or hydrogen (H2) are studied. A mathematical model is developed and compared to experimental studies reported in the literature. At an evaporator temperature of −15 °C, a generator temperature of 120 °C and absorber and condenser temperatures of 40 °C, the results show that the best performance is achieved by the NH3–LiNO3–He mixture, with a COP of 0.48. This mixture performs 27–46% more efficient than the NH3–NaSCN mixture. The NH3–H2O mixture is 52–69% less efficient than the NH3–LiNO3 mixture. However, when the evaporator runs at 7.5 °C, the NH3–H2O–He mixture achieves a more efficient COP than does the NH3–LiNO3–He mixture, and the NH3–NaSCN–He and NH3–LiNO3–He mixtures achieve the same COP when the evaporator is at 10 °C. At temperatures below 7.5 °C, the NH3–NaSCN–He mixture achieves a higher COP than does the NH3–H2O–He mixture. The NH3–LiNO3 mixture shows crystallization at higher temperatures in the generator than does the NH3–NaSCN mixture. Moreover, at the same evaporator temperature, the NH3–LiNO3 mixture works at activation temperatures lower than does the NH3–NaSCN mixture. -- Highlights: ► We studied a diffusion absorption cooling system with different working mixtures. ► The NH3–LiNO3 mixture showed more efficiency than NH3–H2O mixture and NH3–NaSCN mixture. ► The generator and absorber temperature influences on crystallization of the system. ► The NH3–H2O

  13. Thermoelectric refrigerator

    Park, Brian V. (Inventor); Smith, Jr., Malcolm C. (Inventor); McGrath, Ralph D. (Inventor); Gilley, Michael D. (Inventor); Criscuolo, Lance (Inventor); Nelson, John L. (Inventor)

    1996-01-01

    A refrigerator is provided which combines the benefits of superinsulation materials with thermoelectric devices and phase change materials to provide an environmentally benign system that is energy efficient and can maintain relatively uniform temperatures for extended periods of time with relatively low electrical power requirements. The refrigerator includes a thermoelectric assembly having a thermoelectric device with a hot sink and a cold sink. The superinsulation materials include a plurality of vacuum panels. The refrigerator is formed from an enclosed structure having a door. The vacuum panels may be contained within the walls of the enclosed structure and the door. By mounting the thermoelectric assembly on the door, the manufacturer of the enclosed structure is simplified and the overall R rating of the refrigerator increased. Also an electrical motor and propellers may be mounted on the door to assist in the circulation of air to improve the efficiency of the cold sink and the hot sink. A propeller and/or impeller is preferably mounted within the refrigerator to assist in establishing the desired air circulation flow path.

  14. Influence of variable fluid properties during in-tube cooling on performance of CO{sub 2} refrigeration cycle

    Damseh, Rebhi A. [Albalqa Applied Univ., Irbid (Jordan). Mechanical Engineering Dept.

    2006-12-15

    This present study aims to investigate the influence of variable fluid properties on CO{sub 2} tube cooling process. A transient mathematical model for non thermally equilibrium fluid and solid domains is solved by means of finite difference technique. The effect of constant fluid properties assumption on cycle performance is studied. The validity of such assumption is investigated where it is found that it leads to higher gas cooler outlet temperature. The efficiency of the cooler is also affected and will tend the cycle to operate at a erroneous optimum cooling pressure. (orig.)

  15. Refrigeration Showcases

    1997-01-01

    Through the Technology Affiliates Program at the Jet Propulsion Laboratory (JPL), valuable modifications were made to refrigerator displays built by Displaymor Manufacturing Company, Inc. By working with JPL, Displaymor could address stiffer requirements that ensure the freshness of foods. The application of the space technology meant that the small business would be able to continue to market its cases without incurring expenses that could threaten the viability of the business, and the future of several dozen jobs. Research and development improvements in air flow distribution and refrigeration coil technology contributed greatly to certifying Displaymor's showcases given the new federal regulations. These modifications resulted in a refrigerator case that will keep foods cooler, longer. Such changes maintained the openness of the display, critical to customer visibility and accessibility, impulse buying, and cross-merchandising.

  16. Influence of microstructural changes on magnetic refrigeration performance for La(Fe0.94Co0.06)11.8Si1.2 alloys during magnetic field cycling

    Yuan, Z. M.; He, J.; Yang, L.; Xia, Z. J.; Zhao, D. L.; You, C. Y.; Ren, W. J.

    2015-05-01

    NaZn13-type La(Fe0.94Co0.06)11.8Si1.2 alloys were manufactured to investigate the influence of their microstructural change on magnetic refrigeration performance during magnetic field cycling. The magnetic refrigeration performance measurements indicate that both the large magnetic entropy change value (ΔS = 14.1 J kg-1 K-1) and maximum adiabatic temperature change (ΔT = 2.2 K) are favorable for the alloys to be superior candidate of magnetic refrigerants. However, the alloys exhibit nearly 10% decrease of ΔS and ΔT when they performed cycling ten-thousand times. More than thousand times of cycles induce local stress and grain cleavages presented by the accumulation of irreversible microstructure changes such as micro-cracks and sub-boundaries. According to the domain observation for the alloys with different field cycles, these microstructure characteristics accompany with the reconfiguration of the local magnetic domains and increase of domain wall energy, which are considered to be the reason of the decrease of ΔS.

  17. Exergoeconomic Analysis of A Two-stage Absorption Refrigeration System Using the Waste Geothermal Water%地热水双级吸收式制冷系统的火用经济分析

    王永真; 罗向龙; 陈颖; 胡嘉灏; 龚宇烈

    2015-01-01

    With a concern of the vast geothermal waste water during the operation of flash geothermal power plant in Fengshun and the residents′need for cooling load, this paper proposes an integrated sys-tem which synthesizes a TSARS to the original flash power generation cycle, improving the utilization effi-ciency of the geothermal water by taking the advantage of two-stage LiBr-H2 O absorption refrigeration sys-tem( TSARS) in the utilization of low grade heat.First, with the field research made to establish the ex-ergoeconomic model, analysis of this geothermal water integrated system was addressed.Then, Compa-ring the ways of the geothermal water entering the TSARS, it was found that the parallel way is better than the cascade on the exergoeconomic performance.In addition, exergoeconomic analysis of each equipment of the paralleled TSARS was made.All above provide a certain reference to the further actual engineering application.%针对我国丰顺地热电站大量地热尾水直接排弃的问题和当地居民对制冷负荷的需求,基于双级溴化锂吸收式制冷循环( TSARS)在低品位热能利用方面的优势,提出将双级溴化锂吸收式制冷循环应用于地热电站尾水余热的回收,形成地热梯级综合利用系统,以进一步提高地热水的利用率。采用火用经济学分析方法,通过对电站的实地调研,建立地热水TSARS火用经济模型,进而对地热水级联到TSARS的两种可能模式(串联和并联)进行对比分析。结果发现地热水以并联方式供入TSARS具有较好的火用经济性能,同时对设计工况下的地热水并联TSARS的各设备进行了火用经济分析评价,为后期实际工程做参考。

  18. Optimum operating regimes of common paramagnetic refrigerants

    Wikus, P; Figueroa-Feliciano, E

    2011-01-01

    Adiabatic Demagnetization Refrigerators (ADRs) are commonly used in cryogenic laboratories to achieve subkelvin temperatures. ADRs are also the technology of choice for several space borne instruments which make use of cryogenic microcalorimeters or bolometers {[}1-4]. For these applications, refrigerants with high ratios of cooling capacity to volume, or cooling capacity to mass are usually required. In this manuscript, two charts for the simple selection of the most suitable of several common refrigerants (CAA, CMN, CPA, DGG, FAA, GGG, GLF and MAS) are presented. These graphs are valid for single stage cycles. The selection of the refrigerants is uniquely dependent on the starting conditions of the refrigeration cycle (temperature and magnetic field density) and the desired final temperature. Only thermodynamic properties of the refrigerants have been taken into account, and other important factors such as availability and manufacturability have not been considered. (C) 2011 Elsevier Ltd. All rights reserve...

  19. Education in Helium Refrigeration

    On the one hand, at the end of the time I was active in helium refrigeration, I noticed that cryogenics was stepping into places where it was not yet used. For example, a conventional accelerator, operating at room temperature, was to be upgraded to reach higher particle energy. On the other hand, I was a little bit worried to let what I had so passionately learned during these years to be lost. Retirement made time available, and I came gradually to the idea to teach about what was my basic job. I thought also about other kinds of people who could be interested in such lessons: operators of refrigerators or liquefiers who, often by lack of time, did not get a proper introduction to their job when they started, young engineers who begin to work in cryogenics... and so on.Consequently, I have assembled a series of lessons about helium refrigeration. As the audiences have different levels of knowledge in the field of cryogenics, I looked for a way of teaching that is acceptable for all of them. The course is split into theory of heat exchangers, refrigeration cycles, technology and operation of main components, process control, and helium purity

  20. A versatile magnetic refrigeration test device

    Bahl, Christian Robert Haffenden; Petersen, Thomas Frank; Pryds, Nini; Smith, Anders

    2008-01-01

    A magnetic refrigeration test device has been built and tested. The device allows variation and control of many important experimental parameters, such as the type of heat transfer fluid, the movement of the heat transfer fluid, the timing of the refrigeration cycle, and the magnitude of the applied magnetic field. An advanced two-dimensional numerical model has previously been implemented in order to help in the optimization of the design of a refrigeration test device. Qualitative agreement...

  1. Evolution of microstructure in the LaNi5-D system during the early absorption-desorption cycles

    Full text: Our previous study of the activation process in LaNi5 by in-situ neutron powder diffraction provided a fairly clear physical picture of the activation mechanism. During the first absorption, the host matrix absorbs hydrogen to the point of saturation of the α phase. β nuclei then form and physically separate from the parent particles because the misfit strain cannot be supported by the virgin α phase. During the first desorption, in contrast, the α and β phases are able to coexist in the same particles, evidently owing to the existence of a very high density of dislocations in material that has previously absorbed hydrogen. Some significant differences in the behaviour of the lattice parameters and microstrain were noted between this study and our earlier work on a sample which had been absorption-desorption cycled many times. For this reason, we undertook a new study of the first several cycles, including a repeat of the activation cycle. In a single continuous experiment on the same sample, we recorded neutron diffraction patterns during cycles 1, 2 and 5 using HRPD at HIFAR. The results during activation agree very well with those in ref. 1. The results in cycles 2 and 5 are quite similar to those for cycle 1 in desorption. This confirms that the microstructure of the cycled material is essentially established during the very first absorption of hydrogen. Why the absorption plateau pressure continues to decrease discernibly until at least cycle 5 therefore remains something of a mystery. In absorption during cycles 2 and 5, the behaviour of the lattice parameters is similar, but the microstrain behaves quite differently. Hence, the direction in which the phase transformation is executed leads to differing strain regimes, no doubt contributing to the hysteresis between absorption and desorption. Significant differences between this and our first-ever study are observed in the variation of the lattice parameters and the microstrain. These will be

  2. Brownian refrigerator.

    Van den Broeck, C; Kawai, R

    2006-06-01

    Onsager symmetry implies that a Brownian motor, driven by a temperature gradient, will also perform a refrigerator function upon loading. We analytically calculate the corresponding heat flow for an exactly solvable microscopic model and compare it with molecular dynamics simulations. PMID:16803223

  3. Optimal refrigerator

    Allahverdyan, Armen E.; Hovhannisyan, Karen; Mahler, Guenter

    2010-01-01

    We study a refrigerator model which consists of two $n$-level systems interacting via a pulsed external field. Each system couples to its own thermal bath at temperatures $T_h$ and $T_c$, respectively ($\\theta\\equiv T_c/T_h

  4. Refrigeration Servicing.

    Hamilton, Donald L.; And Others

    This self-study course is designed to familiarize Marine enlisted personnel with the services required to be performed on refrigeration equipment. The course contains four study units. Each study unit begins with a general objective, which is a statement of what the student should learn from the unit. The study units are divided into numbered work…

  5. Suitability criterion for a refrigerant for use in solar operated sorption refrigerator

    The thermodynamics of a sorption refrigeration cycle has been discussed representing the cycle on a clapeyron digram. The minimum generation temperature required has been determined using the 'd-a' equation which represents the sorption equilibrium of the pair, and Gibbs free energy relation. The mathematical relation developed provides a totally new basis for determination of suitability of a particular refrigerant. (author)

  6. In vitro developmental competence of pig nuclear transferred embryos: effects of GFP transfection, refrigeration, cell cycle synchronization and shapes of donor cells.

    Zhang, Yun-Hai; Pan, Deng-Ke; Sun, Xiu-Zhu; Sun, Guo-Jie; Liu, Xiao-Hui; Wang, Xiao-Bo; Tian, Xing-Hua; Li, Yan; Dai, Yun-Ping; Li, Ning

    2006-08-01

    The present study was designed to evaluate the feasibility of producing pig transgenic blastocysts expressing enhanced green fluorescent protein (GFP) and to examine the effects of shape and preparation methods of donor cells on in vitro developmental ability of pig nuclear transferred embryos (NTEs). In experiment 1, the effect of GFP transfection on development of pig NTEs was evaluated. The cleavage and blastocyst rates showed no significant difference between NTEs derived from transfected and non-transfected donors. In experiment 2, the effect of different nuclear donor preparation methods on in vitro development of NTEs was examined. The cleavage rate showed no statistically significant differences among three preparation methods. The blastocyst rates of donor cells treated once at -4 degrees C and those of freshly digested cells were similar to each other (26.3% vs 17.9%). The lowest blastocyst rates (5.88%) were observed when cells cryopreserved at -196 degrees C were used as donors. In experiment 3, the effect of different cell cycle synchronization methods on the in vitro development potential of pig NTEs was evaluated. The cleavage rate of NTEs derived from cycling cells was much better than that of NTEs derived from serum-starved cells (64.4% vs 50.5%, p refrigerated pig GFP-transfected cells could be used as donors in nuclear transfer and these NTEs could be effectively developed to blastocyst stage; (ii) serum starvation of GFP-transfected cells is not required for preimplantation development of pig NTEs; and (iii) a rough surface of GFP-transfected donor cells affects fusion rate negatively but has no influence on the cleavage rate or blastocyst rate of pig NTEs. PMID:16822335

  7. 一种喷射器膨胀直接供液制冷循环及性能分析%Performance characteristics of a direct liquid feeding ejector expansion refrigeration cycle

    谢令; 陈光明

    2015-01-01

    很多环保制冷剂如(R1234ze(E))具有蒸发压力低的特点,影响了其制冷性能。提出了将两相喷射器作为膨胀部件,将汽液分离后的纯液体供给蒸发器的直接供液式喷射器膨胀制冷循环(EERC)。以汽车空调系统为例,研究了循环COP与单位容积制冷量,结果表明采用R1234ze(E)的EERC循环相对于采用R134a的传统循环(TRC)COP提升在22%以上,并且容积制冷量也得到大幅提升,与采用R134 a的容积制冷量的差距从33%左右减小到了6%—12%;在高冷凝温度和低蒸发温度工况下,性能改善更加明显。直接供液式EERC无论是直接用来替代现有制冷循环,还是用在环保制冷剂特别是低压环保制冷剂替代传统制冷剂的场合都是一个很好的选择。%Performance of many environmentally friendly refrigerants (eg .R1234ze(E)) in refrigera-tion cycle is greatly affectedbyits low evaporating pressure .A new cycle called direct-liquid-feeding ejector expansion refrigeration cycle ( EERC) was proposed , in which a two-phase ejector works as the only expan-sion device and totallyliquid refrigerant rather than two phase one was fed to the evaporator .Taking automo-tive air-conditioner for example, the COP improvement of the EERC using R1234ze(E) as refrigerant over the traditional cycle(TRC) using R134a as refrigerant can be obtained by more than 22%at giving condi-tions.Besides, volumetric cooling capacity gap between them can be obviously reduced from about 33%to 6%-12%.According to the result , the performance will be much better in the cases of higher condensing temperature and lower evaporating temperature .It is concluded that the direct-liquid-feeding ejector expan-sion refrigeration cycle could be a good choice when using environmentally friendly refrigerants especially with lower evaporatingpressure ones toreplace traditional refrigerants .

  8. Developments in absorptive glass mat separators for cycling applications and 36 V lead-acid batteries

    Toniazzo, V.; Lambert, U.

    The major markets for valve-regulated lead-acid (VRLA) batteries are undergoing a radical upheaval. In particular, the telecommunications industry requires more reliable power supplies, and the familiar 12 V electrical system in cars will probably be soon replaced by a 36/42 V system, or by other electrical systems if part of the automotive market is taken over by hybrid electrical vehicles (HEVs). In order to meet these new challenges and enable VRLA batteries to provide a satisfactory life in float and cycling applications in the telecommunication field, or in the high-rate-partial-state-of-charge service required by both 36/42 V automobiles and HEVs, the lead-acid battery industry has to improve substantially the quality of present VRLA batteries based on absorptive glass mat (AGM) technology. Therefore, manufacturing steps and cell components have to be optimized, especially AGM separators as these are key components for better production yields and battery performance. This paper shows how the optimal segregation of the coarse and fine fibres in an AGM separator structure can improve greatly the properties of the material. The superior capillarity, springiness and mechanical properties of the 100% glass Amerglass multilayer separator compared with commercial monolayer counterparts with the same specific surface-area is highlighted.

  9. High-efficient thermochemical sorption refrigeration driven by low-grade thermal energy

    LI TingXian; WANG RuZhu; WANG LiWei

    2009-01-01

    Thermochemical sorption refrigeration powered by low-grade thermal energy is one of the en ergy-saving and environment friendly green refrigeration technologies. The operation principle of sorption refrigeration system is based on the thermal effects of reversible physicochemical reaction processes between sorbents and refrigerants. This paper presents the developing study on the differ ent thermochemical sorption refrigeration cycles, and some representative high-efficient thermo chemical sorption refrigeration cycles were evaluated and analyzed based on the conventional single-effect sorption cycle. These advanced sorption refrigeration cycles mainly include the heat and mass recovery sorption cycle, double-effect sorption cycle, multi-effect sorption cycle, combined douhie-way sorption cycle, and double-effect and double-way sorption cycle with internal heat recovery.Moreover, the developing tendency of the thermochemical sorption refrigeration is also predicted in this paper.

  10. Graphical expression of thermodynamic characteristics of absorption process in ammonia-water system

    Fortelný Zdeněk

    2012-04-01

    Full Text Available The adiabatic sorption is very interesting phenomenon that occurs when vapor of refrigerant is in contact with unsaturated liquid absorbent-refrigerant mixture and exchange of heat is forbid between the system and an environment. This contribution introduces new auxiliary lines that enable correct position determination of the adiabatic sorption process in the p-T-x diagram of ammoniawater system. The presented auxiliary lines were obtained from common functions for fast calculation of water-ammonia system properties. Absorption cycles designers often utilize p-t-x diagrams of working mixtures for first suggestion of new absorption cycles. The p-t-x diagrams enable fast correct determination of saturate states of liquid (and gaseous mixtures of refrigerants and absorbents. The working mixture isn’t only at saturated state during a real working cycle. If we know pressure and temperature of an unsaturated mixture, exact position determination is possible in the p-t-x diagrams too.

  11. Graphical expression of thermodynamic characteristics of absorption process in ammonia-water system

    Pospíšil, Jiří; Fortelný, Zdeněk

    2012-04-01

    The adiabatic sorption is very interesting phenomenon that occurs when vapor of refrigerant is in contact with unsaturated liquid absorbent-refrigerant mixture and exchange of heat is forbid between the system and an environment. This contribution introduces new auxiliary lines that enable correct position determination of the adiabatic sorption process in the p-T-x diagram of ammoniawater system. The presented auxiliary lines were obtained from common functions for fast calculation of water-ammonia system properties. Absorption cycles designers often utilize p-t-x diagrams of working mixtures for first suggestion of new absorption cycles. The p-t-x diagrams enable fast correct determination of saturate states of liquid (and gaseous) mixtures of refrigerants and absorbents. The working mixture isn't only at saturated state during a real working cycle. If we know pressure and temperature of an unsaturated mixture, exact position determination is possible in the p-t-x diagrams too.

  12. SOLAR REFRIGERATION SYSTEMS BASED ON THE ABSORBER WITH INTERNAL EVAPORATIVE COOLING

    Дорошенко, O.В.; Людницький, К.В.

    2015-01-01

    The paper presents the developed schematics for alternative refrigeration systems and air conditioning systems based on the use of heat-absorption cycle and solar energy for regeneration (recovery) of the absorbent solution. Cascade principle of construction of the drying and cooling circuits with absorbent concentration increasing on the steps of the cascade is used. The absorber with internal evaporative cooling that eliminates a separate evaporative cooler, typically comprised after the co...

  13. Refrigeration plants using carbon dioxide as refrigerant: measuring and modelling the solubility and diffusion of carbon dioxide in polymers used as sealing materials

    von Solms, Nicolas; Kristensen, Jakob

    2010-01-01

    Because of increased environmental pressure, there is currently a movement away from more traditional refrigerants such as HCFC's toward refrigerants with lower global warming potential such as carbon dioxide (CO2). However, the use of CO2 as a refrigerant requires a refrigeration cycle with...

  14. Rotary magnetic refrigerator for superfluid helium production

    A new rotary-magnetic refrigerator designed to obtain superfluid helium temperatures by executing a magnetic Carnot cycle is developed. A rotor containing 12 magnetic refrigerants (gadolinium-gallium-garnet) is immersed in liquid helium at 4.2 K and rotated at constant speed in a steady magnetic field distribution. Performance tests demonstrate that the new rotary refrigerator is capable of obtaining a temperature of 1.48 K. The maximum useful cooling power obtained at 1.8 K is 1.81 W which corresponds to a refrigeration efficiency of 34%

  15. A rotating magnetic refrigerator for helium liquefaction

    This paper presents the first experimental result of a new rotating magnetic refrigerator which uses gadolinium-gallium-garnet (GGG) single crystal as the magnetic material. The refrigerator mainly consists of a rotating disc with 8 pieces of GGG (20 mm in diameter and 10 mm in length), superconducting DC magnets, a heat absorber, a liquid helium reservoir, and a driving motor. The refrigerator operates the reversed Carnot cycle, and a 0.1 W refrigeration power in the 2.87 rpm operation has been achieved under 4.2 K to 8.2 K operation

  16. Fluorescent refrigeration

    Epstein, Richard I.; Edwards, Bradley C.; Buchwald, Melvin I.; Gosnell, Timothy R.

    1995-01-01

    Fluorescent refrigeration is based on selective radiative pumping, using substantially monochromatic radiation, of quantum excitations which are then endothermically redistributed to higher energies. Ultimately, the populated energy levels radiatively deexcite emitting, on the average, more radiant energy than was initially absorbed. The material utilized to accomplish the cooling must have dimensions such that the exciting radiation is strongly absorbed, but the fluorescence may exit the material through a significantly smaller optical pathlength. Optical fibers and mirrored glasses and crystals provide this requirement.

  17. Operation features of the dilution refrigerator with condensation pumping

    Dilution refrigerators with cryogenic circulation cycle of 3 He have advantages in comparison with other models. One of the most promising designs of such refrigerators is the dilution refrigerator with condensation pumping of 3 He. The design is described and its operation analyzed

  18. Magnetic refrigerator for hydrogen liquefaction

    Numazawa, T [National Institute for Materials Science, Tsukuba (Japan); Kamlya, K. [Japan Atomic Energy Agency, Naka (Japan); Utaki, T. [Osaka University, Osaka (Japan); Matsumoto, K. [Kanazawa University, Kanazawa (Japan)

    2013-06-15

    This paper reviews the development status of magnetic refrigeration system for hydrogen liquefaction. There is no doubt that hydrogen is one of most important energy sources in the near future. In particular, liquid hydrogen can be utilized for infrastructure construction consisting of storage and transportation. Liquid hydrogen is in cryogenic temperatures and therefore high efficient liquefaction method must be studied. Magnetic refrigeration which uses the magneto-caloric effect has potential to realize not only the higher liquefaction efficiency > 50 %, but also to be environmentally friendly and cost effective. Our hydrogen magnetic refrigeration system consists of Carnot cycle for liquefaction stage and AMR (active magnetic regenerator) cycle for precooling stages. For the Carnot cycle, we develop the high efficient system > 80 % liquefaction efficiency by using the heat pipe. For the AMR cycle, we studied two kinds of displacer systems, which transferred the working fluid. We confirmed the AMR effect with the cooling temperature span of 12 K for 1.8 T of the magnetic field and 6 second of the cycle. By using the simulation, we estimate the total efficiency of the hydrogen liquefaction plant for 10 kg/day. A FOM of 0.47 is obtained in the magnetic refrigeration system operation temperature between 20 K and 77 K including LN2 work input.

  19. Magnetic refrigerator for hydrogen liquefaction

    This paper reviews the development status of magnetic refrigeration system for hydrogen liquefaction. There is no doubt that hydrogen is one of most important energy sources in the near future. In particular, liquid hydrogen can be utilized for infrastructure construction consisting of storage and transportation. Liquid hydrogen is in cryogenic temperatures and therefore high efficient liquefaction method must be studied. Magnetic refrigeration which uses the magneto-caloric effect has potential to realize not only the higher liquefaction efficiency > 50 %, but also to be environmentally friendly and cost effective. Our hydrogen magnetic refrigeration system consists of Carnot cycle for liquefaction stage and AMR (active magnetic regenerator) cycle for precooling stages. For the Carnot cycle, we develop the high efficient system > 80 % liquefaction efficiency by using the heat pipe. For the AMR cycle, we studied two kinds of displacer systems, which transferred the working fluid. We confirmed the AMR effect with the cooling temperature span of 12 K for 1.8 T of the magnetic field and 6 second of the cycle. By using the simulation, we estimate the total efficiency of the hydrogen liquefaction plant for 10 kg/day. A FOM of 0.47 is obtained in the magnetic refrigeration system operation temperature between 20 K and 77 K including LN2 work input.

  20. CO2双级压缩制冷热泵循环性能研究%Performance Analysis of CO2 Two-stage Compression Refrigeration Heat Pump Cycle

    刘雄; 姜乔乔; 郭浩波

    2011-01-01

    This paper proposed a two-stage compression refrigeration heat pump cycle. It can not only recycle waste heat generated by refrigeration, but also supply cooling and domestic hot water at the same time according to the users need. Using actual cases, they are analyzed theoretically that the refrigerant mass flow rate, environment temperature, hot water temperature, high pressure compressor's exhaust pressure have influence on the new cycle's properties. In addition, the effect factors of the characteristic temperature and high pressure compressors optimum exhaust pressure are discussed.%提出了一种CO2双级压缩制冷热泵循环,它能够实现冷热量的同时独立调节;并通过实际案例,理论分析了不同制冷剂质量流量系数、不同环境温度、热水温度以及高压压缩机排气压力下,新循环的性能,考察了特征温度和最佳排气压力的影响因素.

  1. Refrigeration and Food Safety

    ... Forms Standard Forms FSIS United States Department of Agriculture Food Safety and Inspection Service About FSIS District ... 286) Actions ${title} Loading... Refrigeration and Food Safety History of Refrigeration Importance of Refrigeration Types of Bacteria ...

  2. High-efficiency absorption-type heat pumps and refrigerators. From topology to the pilot plant; Hocheffiziente Absorptionsmaschinen zur Versorgung mit Kaelte und Waerme. Von der Topologie zur Pilotanlage

    Ziegler, F.; Demmel, S.; Lamp, P. [Bayerisches Zentrum fuer Angewandte Energieforschung e.V. (ZAE Bayern), Wuerzburg (Germany); Kahn, R. [Technische Univ. Muenchen (Germany). Physik Dept. E19; Alefeld, G.

    1998-12-31

    Absorption-type heat pumps or refrigerators are systems operated with heat. They have been known for a long time and are frequently used especially in airconditioning in the USA and south-east Asia. However, the conventional technique used is subject to many physical limitations, restricting their broader use. The paper demonstrates ways of overcoming these restrictions, for instance by multi-stage design. The exploitation of topological principles much facilitates the synthesis of novel circuits. The technical relevance of such developments is demonstrated by means of selected examples of executed laboratory and pilot plants. Modern absorption technology saves resources and prevents environmental pollution by consuming less fossil energy compared with the conventional technique, for instance by harnessing the thermal potential of solar energy or utilizing waste heat and residual heat, and, not least, thanks to the use of natural refrigerants. (orig.) [Deutsch] Absorptionswaermepumpen oder -kaeltemaschinen sind durch Waerme angetriebene Anlagen, die seit langem bekannt sind und besonders in der Klimatechnik in den USA und im suedostasiatischen Raum haeufig eingesetzt werden. Die dabei verwendete konventionelle Technik unterliegt allerdings vielfaeltigen physikalischen Einschraenkungen, die ihre noch breitere Anwendung verhindern. Es wird gezeigt, wie diese Einschraenkungen beispielsweise durch Mehrstufigkeit ueberwunden werden koennen. Durch die Verwendung topologischer Grundsaetze wird die Synthese neuartiger Kreislaeufe stark vereinfacht. Die technische Bedeutung solcher Entwicklungen wird an ausgewaehlten Beispielen ausgefuehrter Labor- und Pilotanlagen gezeigt. Durch den im Vergleich zu konventioneller Technik geringeren Verbrauch an fossiler Energie, beispielsweise durch die thermische Nutzung von Sonnenenergie oder durch die Nutzung von Ab- oder Restwaerme und nicht zuletzt durch die Verwendung natuerlicher Kaeltemittel werden bei Einsatz moderner

  3. Magnetic refrigeration study at CEA Grenoble

    Two kinds of applications are considered for magnetic refrigeration, first in the 1.80K range mainly for He II cooling of superconductors and second for He I refrigeration with precooling near 20 K. At He II temperatures, refrigeration by a Carnot cycle has been investigated and analysed. We give a survey of the results which demonstrate the capability of magnetic refrigeration to attain high thermodynamic efficiency. More interest is now devoted to He I cooling for which we compare magnetic refrigeration to the standard existing solutions. For temperatures higher than 10 K, we discuss the interest and the constraints of cycles with internal heat exchange. Analysis of various configurations is given to explain the choice of a new experiment being built

  4. Modélisation et simulation numérique d'un cycle à absorption irréversible

    Bouaziz, Nahla; Ben Romdane, Hamdi; Ahachad, Mohamed; Belghith, Ali

    2007-01-01

    Le présent travail, concerne un modèle d'étude et d'optimisation d'un cycle à absorption irréversible fonctionnant entre quatre sources de températures. Les principes et les lois de la thermodynamique ainsi que les équations de transfert de chaleur et de masse, exprimés pour le cycle frigorifique, compose la base mathématique de ce modèle. A ceux-ci se rajoutent les irréversibilités interne et externe de la machine à absorption. La confrontation des résultats de la simulation numérique complè...

  5. Exergetic sustainability evaluation of irreversible Carnot refrigerator

    Açıkkalp, Emin

    2015-10-01

    Purpose of this paper is to assess irreversible refrigeration cycle by using exergetic sustainability index. In literature, there is no application of exergetic sustainability index for the refrigerators and, indeed, this index has not been derived for refrigerators. In this study, exergetic sustainability indicator is presented for the refrigeration cycle and its relationships with other thermodynamics parameters including COP, exergy efficiency, cooling load, exergy destruction, ecological function and work input are investigated. Calculations are conducted for endoreversible and reversible cycles and then results obtained from the ecological function are compared. It is found that exergy efficiency, exergetic sustainable index reduce 47.595% and 59.689% and rising at the COP is 99.888% is obtained for endoreversible cycle. Similarly, exergy efficiency and exergetic sustainability index reduce 90.163% and 93.711% and rising of the COP is equal to 99.362%.

  6. Low-temperature magnetic refrigerator

    The disclosure is directed to a low temperature 4 to 20 K. refrigeration apparatus and method utilizing a ring of magnetic material moving through a magnetic field. Heat exchange is accomplished in and out of the magnetic field to appropriately utilize the device to execute Carnot and Stirling cycles

  7. Modelling (using artificial neural-networks) the performance parameters of a solar-driven ejector-absorption cycle

    Theoretical thermodynamic analysis of the absorption thermal systems is at present too complex because of analytic functions calculating the thermodynamic properties of fluid couples involving the solution of complex differential equations and simulation programs. This paper proposes a new approach to performance analysis of a solar-driven ejector-absorption refrigeration system (EARS) with an aqua/ammonia working fluid. Use of artificial neural-networks (ANNs) has been proposed to determine the performance parameters as functions of only the working temperature, under various working conditions. Thus, this study is considered to be helpful in predicting the performance of an EARS prior to it being set up in an environment where the temperatures are known. The statistical coefficient of multiple determinations (R2 - value) equals to 0.976, 0.9825, 0.9855 for the coefficient of performance (COP), exergetic coefficient of performance (ECOP) and circulation ratio (F), respectively. These accuracies are acceptable for the design of an EARS. The present method greatly reduces the time required by design engineers to find the optimum solution and in many cases reaches a solution that could not be easily obtained from simple modelling programs. The importance of the ANN approach, apart from reducing the time required, is that it is possible to find solutions that make solar-energy applications more viable and thus more attractive to potential users, such as solar engineers. Also, this approach has the advantages of computational speed, low cost for feasibility, rapid turnaround (which is especially important during iterative design-phases), and ease of design by operators with little technical experience

  8. Investigation of hydride powder bed swelling and shrinking during hydrogen absorption/desorption cycles under different compressive stresses

    Highlights: ► Decrepitation creates hydride bed densification while cycling under hydrogen. ► Axial compressive stress decreases the ability of a hydride bed to change its volume. ► Internal friction increases along with cycles. ► Friction of the hydride with the side walls increases the powder density. -- Abstract: The solid storage through hydrides allows good compactness and safety due to low pressure. Intermetallic hydride materials have a significant volume increase and decrease (10–35%) upon absorption/desorption respectively. The measurement of the mechanical behavior of these materials is of major interest for the design of H2 storage tanks. In the present work, Ti–V–Cr hydride powder beds underwent hydrogen absorption/desorption cycles in a cylindrical instrumented cell with a mobile upper piston. Different compressive stresses have been applied by the piston and a spring on the powder bed. The variations of samples volume were measured upon cycling and analyzed while considering the mechanical behavior of this granular medium. In particular, part of the volume change is balanced by the variation of the intergranular porosity of the granular media. Changing upper stress reveals the combined importance of the powder sample friction on the cell side walls, and of internal friction strongly influenced by the grains interlocking in the cyclic powder densification process observed

  9. Experience with two large-scale Hell-cryostats for a superconducting RF particle separator working in closed cycle with a 300 W refrigerator

    Barth, W

    1976-01-01

    The contribution of the Karlsruhe Institut fur Experimental Kernphysik to the RF particle separator at the SPS/CERN consists of the two superconducting deflectors and their Hell-cryostats with the cryogenic and vacuum accessories. The cryostats have to fulfil specifications concerning tightness, thermal insulation, adjustment of the cavities to the beam and reliability. Corresponding cryogenic and RF tests are performed in Karlsruhe before a 300 W refrigerator simulating normal and emergency conditions. Following a description of cryostats design the results of these measurements are compared with the specifications. Operating experience with the cryostats in closed circuit with the refrigerator are reported. (5 refs).

  10. SIMULATION OF NON-AZEOTROPIC REFRIGERANT MIXTURES FOR USE IN A DUAL-CIRCUIT REFRIGERATOR/FREEZER WITH COUNTERCURRENT HEAT EXCHANGES

    The paper discusses a refrigerator/freezer (RF) system that has two complete and independent refrigeration cycles for the two compartments. It uses a non-azeotropic refrigerant mixture (NARM) in each cycle and countercurrent heat exchangers throughout. This RF is housed in a stan...

  11. Applications of Jet Ejectors for efficient refrigeration and modelling of Multi Phase Multi Fluid flow in Ejectors

    Konar, D.

    2015-09-01

    The uses of ejector for efficient refrigeration are manifold - it has been used, among other applications, in the VCRS to reduce the compression ratio, in the combined ejector absorption cycle to enhance the refrigeration capacity and in the ejector absorber cycle to obtain lower evaporator pressures, higher absorber pressures and pre-absorption of the refrigerant in the ejector. Hence, modeling of flow which may be two phase two fluid as in ejector absorber cycle or two phase single fluid as in VCRS in an ejector assumes utmost importance. However, much work has not been done in this field. The primary objective of the present work is to discuss about the role of ejectors in various refrigeration systems and to model the two phase two fluid flow in the nozzle and the diffuser of an ejector under suitable assumptions. The equations of conservation of mass, momentum and energy have been solved to find the different flow properties like pressure, temperature and velocity of the two phases as function of the length in the diffuser. Different cases pertaining to different flows have been taken care of by appreciating what type of phenomena can actually occur at the interface of the two phases. Higher pressure rise was obtained for a given diffuser length with higher diffuser angles, smaller droplet diameter, higher inlet velocity of the gaseous phase and higher drag coefficients. Among other results, it was also seen that the two phases reached thermal equilibrium faster with higher diffuser angle, smaller droplet diameter and higher heat transfer coefficient.

  12. U.S. Residential Miscellaneous Refrigeration Products: Results from Amazon Mechanical Turk Surveys

    Greenblatt, Jeffery B.; Young, Scott J.; Yang, Hung-Chia; Long, Timothy; Beraki, Bereket; Price, Sarah K.; Pratt, Stacy; Willem, Henry; Desroches, Louis-Benoit

    2013-11-14

    Amazon Mechanical Turk was used, for the first time, to collect statistically representative survey data from U.S. households on the presence, number, type and usage of refrigerators, freezers, and various “miscellaneous” refrigeration products (wine/beverage coolers, residential icemakers and non-vapor compression refrigerators and freezers), along with household and demographic information. Such products have been poorly studied to date, with almost no information available about shipments, stocks, capacities, energy use, etc. A total of 9,981 clean survey responses were obtained from five distinct surveys deployed in 2012. General refrigeration product survey responses were weighted to demographics in the U.S. Energy Information Administration’s Residential Energy Consumption Survey 2009 dataset. Miscellaneous refrigeration product survey responses were weighted according to demographics of product ownership found in the general refrigeration product surveys. Model number matching for a portion of miscellaneous refrigeration product responses allowed validation of refrigeration product characteristics, which enabled more accurate estimates of the penetrations of these products in U.S. households. We estimated that there were 12.3±1.0 million wine/beverage coolers, 5.5(–3.5,+3.2) million residential icemakers and 4.4(–2.7,+2.3) million non-vapor compression refrigerators in U.S. households in 2012. (All numerical results are expressed with ranges indicating the 95% confidence interval.) No evidence was found for the existence of non-vapor compression freezers. Moreover, we found that 15% of wine/beverage coolers used vapor compression cooling technology, while 85% used thermoelectric cooling technology, with the vast majority of thermoelectric units having capacities of less than 30 wine bottles (approximately 3.5 cubic feet). No evidence was found for the existence of wine/beverage coolers with absorption cooling technology. Additionally, we estimated

  13. REACH. Refrigeration Units.

    Snow, Rufus; And Others

    As a part of the REACH (Refrigeration, Electro-Mechanical, Air-Conditioning, Heating) electromechanical cluster, this student manual contains individualized instructional units in the area of refrigeration. The instructional units focus on refrigeration fundamentals, tubing and pipe, refrigerants, troubleshooting, window air conditioning, and…

  14. Optimization study of a single-effect water–lithium bromide absorption refrigeration system powered by flat-plate collector in hot regions

    Highlights: • A comprehensive analysis for optimizing solar absorption system in hot region. • The most important parameter to be controlled is hot source temperature. • Ensuring appropriate choice of parameters, COP of absorption unit exceeds 0.8. • Results show that solar cooling systems are promising in hot regions. • The research aims to play a vital role to promote the use of renewable energy. - Abstract: This investigation has been carried out to present a comprehensive analysis for optimizing the operation of solar absorption system in hot regions. To optimize performance of the system, the hot source temperature should be controlled in function of incident solar radiation, chilled and cooling water temperatures. With an appropriate control, these external conditions can be monitored to detect and implement the actual optimization conditions. Adopting typical values encountered in hot regions, the overall system performance takes its optimal value at temperatures between 75 and 80 °C. It was found that in designing or selecting solar collector, selective coating type is necessary to produce hot water with potential around 80–90 °C needed to optimize operation of absorption unit. By ensuring an appropriate choice of components temperatures, COP of absorption unit can exceed the value 0.8. Cooling water temperature above 40 °C reduces significantly the performance of the unit which requires, under conditions of extremely high external temperatures, dimensioning and selection of condensers and absorbers that guarantee values less than this limit

  15. Refrigeration generation using expander-generator units

    Klimenko, A. V.; Agababov, V. S.; Koryagin, A. V.; Baidakova, Yu. O.

    2016-05-01

    The problems of using the expander-generator unit (EGU) to generate refrigeration, along with electricity were considered. It is shown that, on the level of the temperatures of refrigeration flows using the EGU, one can provide the refrigeration supply of the different consumers: ventilation and air conditioning plants and industrial refrigerators and freezers. The analysis of influence of process parameters on the cooling power of the EGU, which depends on the parameters of the gas expansion process in the expander and temperatures of cooled environment, was carried out. The schematic diagram of refrigeration generation plant based on EGU is presented. The features and advantages of EGU to generate refrigeration compared with thermotransformer of steam compressive and absorption types were shown, namely: there is no need to use the energy generated by burning fuel to operate the EGU; beneficial use of the heat delivered to gas from the flow being cooled in equipment operating on gas; energy production along with refrigeration generation, which makes it possible to create, using EGU, the trigeneration plants without using the energy power equipment. It is shown that the level of the temperatures of refrigeration flows, which can be obtained by using the EGU on existing technological decompression stations of the transported gas, allows providing the refrigeration supply of various consumers. The information that the refrigeration capacity of an expander-generator unit not only depends on the parameters of the process of expansion of gas flowing in the expander (flow rate, temperatures and pressures at the inlet and outlet) but it is also determined by the temperature needed for a consumer and the initial temperature of the flow of the refrigeration-carrier being cooled. The conclusion was made that the expander-generator units can be used to create trigeneration plants both at major power plants and at small energy.

  16. Development of solar driven absorption air conditioners and heat pumps

    Dao, K.; Wahlig, M.; Wali, E.; Rasson, J.; Molishever, E.

    1980-03-01

    The development of absorption refrigeration systems for solar active heating and cooling applications is discussed. The approaches investigated are those using air-cooled condenser-absorber and those leading to coefficient of performances (COP) that increase continuously with heat source temperature. This is primarily an experimental project, with the emphasis on designing, fabricating and testing absorption chillers in operating regimes that are particularly suited for solar energy applications. Its demonstrated that the conventional single-effect ammonia-water absorption cycle can be used (with minor modifications) for solar cooling.

  17. Harmful and Needless Emission of Refrigerant and Countermeasures

    Wu Zeqiu

    2009-01-01

    Refrigerants used in refrigerators are an important source of ozone depleting substances released into the atmosphere,and can have a significantly negative effect on the hole in the ozone layer.But most emission of refrigerants is man-made,unreasonable and needless.Since in most emission cases the refrigerants are contained in the refrigerators,we can retrieve them by some technique that changes the 'manual emission' into manual retrieving.To promote the retrieval action and diminish the pollution,society can use economic,administrative and technical countermeasures,which can create a 'good-cycle' both 'harnessing pollution and earning income simultaneously',reinforce the motive of retrieving,and retrieve most proportion of refrigerants used by all refrigerators.This 'good-cycle' method can be easily promoted,and also a valuable way to promote other forms of environmental protection.The three countermeasures have almost no social cost,even no cost at all.

  18. Anomalous Brownian refrigerator

    Rana, Shubhashis; Pal, P. S.; Saha, Arnab; Jayannavar, A. M.

    2016-02-01

    We present a detailed study of a Brownian particle driven by Carnot-type refrigerating protocol operating between two thermal baths. Both the underdamped as well as the overdamped limits are investigated. The particle is in a harmonic potential with time-periodic strength that drives the system cyclically between the baths. Each cycle consists of two isothermal steps at different temperatures and two adiabatic steps connecting them. Besides working as a stochastic refrigerator, it is shown analytically that in the quasistatic regime the system can also act as stochastic heater, depending on the bath temperatures. Interestingly, in non-quasistatic regime, our system can even work as a stochastic heat engine for certain range of cycle time and bath temperatures. We show that the operation of this engine is not reliable. The fluctuations of stochastic efficiency/coefficient of performance (COP) dominate their mean values. Their distributions show power law tails, however the exponents are not universal. Our study reveals that microscopic machines are not the microscopic equivalent of the macroscopic machines that we come across in our daily life. We find that there is no one to one correspondence between the performance of our system under engine protocol and its reverse.

  19. Cycle performance studies on a new HFC-161/125/143a mixture as an alternative refrigerant to R404A

    Xiao-hong HAN; Yu QIU; Ying-jie XU; Men-yuan ZHAO; Qin WANG; Guang-ming CHEN

    2012-01-01

    In this paper,a new ternary non-azeotropic mixture of HFC-161/125/143a (0.15/0.45/0.40 in mass fraction),as a promising mixed refrigerant to R404A,is presented.The ozone depletion potential (ODP) of the new refrigerant is zero and its basic thermodynamic properties are similar to those of R404A,but its global warming potential (GWP) is much smaller than those of R507A and R404A.Meanwhile,theoretical calculations show that,under the working condition Ⅰ (the average evaporation temperature:-23 ℃,the average condensing temperature:43 ℃,the superheat temperature:28 ℃,the subcooling temperature:5 ℃),the volumetric refrigerating effect and specific refrigerating effect of the new mixture are 2.33% and 15.48% higher,respectively,than those of R404A.The coefficient of performance (COP) of the new mixture is 5.19% higher than that of R404A and the pressure ratio of the new mixture is 0.82% lower than that of R404A.Equally,under the working condition Ⅱ (the average evaporation temperature:-40 ℃,the average condensing temperature:35 ℃,the superheating temperature:30 ℃,the subcooling temperature:5 ℃),the volumetric refrigerating effect and specific refrigerating effect of the new mixture are 2.24% and 20.58% higher,respectively,than those of R404A.The COP of the new mixture is 4.60% higher than that of R404A and the pressure ratio of the new mixture is similar to that of R404A.The performances of the new mixture and R404A are compared in a vapor compressor refrigeration apparatus originally designed for R404A under several working conditions (condensing temperatures:35-45 ℃,evaporation temperatures:-40-20 ℃).Experimental results show that the new mixture can obtain a higher COP,by 6.3% to 12.1%,and a lower pressure ratio,by 1.8% to 6.6%,compared to R404A; although the discharge temperature of the new mixture is slightly higher than that of R404A.The advantages of the new mixture will be further verified in the actual system.

  20. New refrigeration system using CO2 vapor-solid as refrigerant

    Dongping HUANG; Guoliang DING; Hans QUACK

    2008-01-01

    A refrigerant must be in the vapor-liquid phase in a vapor-compression refrigeration system, therefore, CO2 cannot be used as a refrigerant for temperatures lower than -56℃ because solid CO2 will form under the triple point temperature of -56℃. A refrigeration system with CO2 vapor-solid particles as refrigerant is put forward, by which a temperature lower than the triple point is achieved. An adjustable nozzle, a sublimator, a high-pressure regulating valve and a low-pressure regulat-ing valve are used to replace the conventional evaporator. Theoretical cycle analysis of the refrigeration system shows that its COP can be 50% higher than that of the conventional one.

  1. ARTI refrigerant database

    Calm, J.M.

    1996-11-15

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern.

  2. ARTI refrigerant database

    Calm, J.M.

    1996-07-01

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern.

  3. ARTI refrigerant database

    Calm, J.M. [Calm (James M.), Great Falls, VA (United States)

    1999-01-01

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilities access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern.

  4. Dynamic simulation of a reverse Brayton refrigerator

    Peng, N.; Xiong, L. Y.; Dong, B.; Liu, L. Q. [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, CAS, Beijing, 100190 (China); Lei, L. L.; Tang, J. C. [State Key Laboratory of Technologies in Space Cryogenic Propellants, Technical Institute of Physics and Chemistry, CAS, Beijing, 100190 China and Graduate University of Chinese Academy of Sciences, Beijing, 100190 (China)

    2014-01-29

    A test refrigerator based on the modified Reverse Brayton cycle has been developed in the Chinese Academy of Sciences recently. To study the behaviors of this test refrigerator, a dynamic simulation has been carried out. The numerical model comprises the typical components of the test refrigerator: compressor, valves, heat exchangers, expander and heater. This simulator is based on the oriented-object approach and each component is represented by a set of differential and algebraic equations. The control system of the test refrigerator is also simulated, which can be used to optimize the control strategies. This paper describes all the models and shows the simulation results. Comparisons between simulation results and experimental data are also presented. Experimental validation on the test refrigerator gives satisfactory results.

  5. Dynamic simulation of a reverse Brayton refrigerator

    A test refrigerator based on the modified Reverse Brayton cycle has been developed in the Chinese Academy of Sciences recently. To study the behaviors of this test refrigerator, a dynamic simulation has been carried out. The numerical model comprises the typical components of the test refrigerator: compressor, valves, heat exchangers, expander and heater. This simulator is based on the oriented-object approach and each component is represented by a set of differential and algebraic equations. The control system of the test refrigerator is also simulated, which can be used to optimize the control strategies. This paper describes all the models and shows the simulation results. Comparisons between simulation results and experimental data are also presented. Experimental validation on the test refrigerator gives satisfactory results

  6. Nonlinear ultrafast modulation of the optical absorption of few cycle terahertz pulses in n-doped semiconductors

    Razzari, L; Sharma, G; Blanchard, F; Ayesheshim, A; Bandulet, H-C; Morandotti, R; Kieffer, J-C; Ozaki, T; Reid, M; Hegmann, F A

    2009-01-01

    We use an open-aperture Z-scan technique to show how intense few-cycle terahertz pulses can experience a nonlinear bleaching of absorption in an n-doped semiconductor due to terahertz-electric-field-driven intervalley scattering of electrons in the conduction band. Coherent detection of the transmitted terahertz pulse waveform also allows the nonlinear conductivity dynamics to be followed with sub-picosecond time resolution. Both the Z-scan and time-domain results are found to be in agreement with our theoretical analysis.

  7. MAGNETOHYDRODYNAMICS: A METHOD FOR PERFORMANCE ENHANCEMENT IN AIR CONDITIONING AND REFRIGERATION

    N.S.Mane; , H.M.Dange; P. P. Awate

    2015-01-01

    The refrigeration and air conditioning system having low energy consumption and environment friendliness is the main focus of the research department Refrigeration and Air conditioning industry and technical institutes. Efficiency of the refrigeration or air conditioning system working on vapour compression refrigeration cycle can be increased by using the Magneto hydrodynamic principles. Many researchers indicated that the behavior of the refrigerant flowing through vapour compre...

  8. 跨临界CO2引射制冷循环运行稳定性研究%The Operation Stability Research on the Transcritical CO2 Ejector Expansion Refrigeration Cycle

    邓建强

    2011-01-01

    Present work analyzed the operation stability of the transcritical CO2 ejector expansion refrigeration cycle. Thermodynamic models of two kinds adjusting schemes which maintain cycle stable, i.e. feedback vapor and two-stage evaporation were set up. The simulation result shows that cycle with vapor feedback adjusting control has highly similar refrigeration effect with the basic ejector expansion cycle which controlled by the entrainment ratio. The cycle with two-stage evaporation improves the refrigeration performance obviously. The adjustable district of vapor feedback control becomes narrower with the entrainment ratio decreasing. By contrast, the adjustable district of the two-stage evaporation control broadens. With regards to the vapor feedback adjusting control, considering the optimize of the COP and the wider adjustable working condition, the ejector coefficient is suitable in 0.6-0.7.%分析了跨临界CO2引射制冷循环的运行稳定性问题,对蒸气反馈和两级蒸发两种致引射系统稳定的调控方案构建了热力学模型。模拟研究表明蒸气反馈调控系统具有与基本引射循环调控引射系数致系统稳定非常相似的制冷效果。而两级蒸发调控可明显提高系统的制冷性能。引射系数越小,蒸气反馈调控的可调工况区间越窄,两级蒸发方案的可调工况区间越宽。对于蒸气反馈调控,同时考虑COP优化和具较宽的可调工况,引射系数在0.6-0.7间较合适。

  9. 太阳能水蒸气引射冷却的CO2低温制冷循环%CO2 Refrigeration Cycle of Solar Energy Water Vapor Entrainment Cooling for Low Temperature

    宁静红; 刘圣春; 郭宪民

    2012-01-01

    为需要较低温度的用冷空间提供冷源,设计由太阳能集热循环,水蒸气喷射制冷循环,CO2低温制冷循环组成的太阳能辅助热源水蒸气喷射引射冷却的CO2低温制冷的组合循环,通过热力计算得出随着蒸发温度的升高,太阳能辐射强度的增大,集热器面积的增大,组合循环的性能提高.蒸发温度每升高1℃,组合循环的性能系数增大4.3%,太阳能辐射强度每增加1 W/m2,组合循环的性能系数增大2.8%,太阳能集热器面积每增加1 m2,组合循环的性能系数增大约6%.发生器内水蒸气温度对组合循环的性能影响不大,太阳能辐射强度、集热器面积以及喷射器引射率对组合循环的影响较大.组合循环节省运行费用,节约能源,有很好的发展前景.%The combined cycle of solar energy - driven water vapor ejector entrainment cooling CO2 refrigeration cycle is designed for providing low temperature space. This combined cycle is composed of solar energy heat-collecting cycle, water vapor e-jector refrigeration cycle and CO2 low temperature refrigeration cycle. By thermodynamic calculation, the results are obtained that the COP of combined cycle increase as the enhancing of evaporation temperature, solar energy radiant intensity and solar collector area. When the evaporation temperature increase 1℃ , the COP of combined cycle enhance about 4.3% , the radiant intensity of solar energy increase 1 W/m2, the COP of combined cycle enhance about 2. 8% , and the solar collector area increase lm2, the COP of combined cycle enhance about 6% . However, the effect of water vapor temperature in generator on the performance of combined cycle is not obvious. Moreover the effect of the solar energy radiant intensity, the solar collector area and the ejector entrainment ratio are higher on the COP of combined cycle. It is gained that the performance of combined system has obvious advantage for reducing running cost and saving energy, so

  10. A versatile magnetic refrigeration test device.

    Bahl, C R H; Petersen, T F; Pryds, N; Smith, A

    2008-09-01

    A magnetic refrigeration test device has been built and tested. The device allows variation and control of many important experimental parameters, such as the type of heat transfer fluid, the movement of the heat transfer fluid, the timing of the refrigeration cycle, and the magnitude of the applied magnetic field. An advanced two-dimensional numerical model has previously been implemented in order to help in the optimization of the design of a refrigeration test device. Qualitative agreement between the results from model and the experimental results is demonstrated for each of the four different parameter variations mentioned above. PMID:19044427

  11. A versatile magnetic refrigeration test device

    Bahl, Christian Robert Haffenden; Petersen, Thomas Frank; Pryds, Nini;

    2008-01-01

    A magnetic refrigeration test device has been built and tested. The device allows variation and control of many important experimental parameters, such as the type of heat transfer fluid, the movement of the heat transfer fluid, the timing of the refrigeration cycle, and the magnitude of the...... applied magnetic field. An advanced two-dimensional numerical model has previously been implemented in order to help in the optimization of the design of a refrigeration test device. Qualitative agreement between the results from model and the experimental results is demonstrated for each of the four...

  12. Performance Analysis of Multipurpose Refrigeration System (MRS on Fishing Vessel

    Ust Y.

    2016-04-01

    Full Text Available The use of efficient refrigerator/freezers helps considerably to reduce the amount of the emitted greenhouse gas. A two-circuit refrigerator-freezer cycle (RF reveals a higher energy saving potential than a conventional cycle with a single loop of serial evaporators, owing to pressure drop in each evaporator during refrigeration operation and low compression ratio. Therefore, several industrial applications and fish storage systems have been utilized by using multipurpose refrigeration cycle. That is why a theoretical performance analysis based on the exergetic performance coefficient, coefficient of performance (COP, exergy efficiency and exergy destruction ratio criteria, has been carried out for a multipurpose refrigeration system by using different refrigerants in serial and parallel operation conditions. The exergetic performance coefficient criterion is defined as the ratio of exergy output to the total exergy destruction rate (or loss rate of availability. According to the results of the study, the refrigerant R32 shows the best performance in terms of exergetic performance coefficient, COP, exergy efficiency, and exergy destruction ratio from among the other refrigerants (R1234yf, R1234ze, R404A, R407C, R410A, R143A and R502. The effects of the condenser, freezer-evaporator and refrigerator-evaporator temperatures on the exergetic performance coefficient, COP, exergy efficiency and exergy destruction ratios have been fully analyzed for the refrigerant R32.

  13. Contribution to magnetic refrigeration study at liquid helium study

    An experimental prototype of magnetic refrigerator operates, following a Carnot cycle, with gallium gadolinium garnet, from liquid helium at 4.20K. Analysis of the cyle and heat exchanges allowed to improve performance up to get more than 50% of Carnot yield at 1.80K and nearly 80% at 2.10K. Operation conditions of a regenerator refrigerator between 4 and 200K are studied. The association of a magnetic refrigerator and a gas refrigerator is analyzed. Among different ways to realize the magnetic stage, an active regenerator cycle is chosen. An experimental device is described

  14. Neutron radiography visualization of internal processes in refrigerators

    Dynamic neutron radiography was used to visualize the characteristic features of evaporation, condensation, fluid flow and clogging points in absorption-type refrigerators. Environment friendly new constructions of compression-type refrigerators were investigated. The results provide an effective tool for manufacturers to improve their products. (orig.)

  15. ARTI Refrigerant Database

    Calm, J.M. [Calm (James M.), Great Falls, VA (United States)

    1994-05-27

    The Refrigerant Database consolidates and facilitates access to information to assist industry in developing equipment using alternative refrigerants. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern.

  16. FR-II Broad Absorption Line Quasars and the Life Cycle of Quasars

    Gregg, M D; Becker, R H; de Vries, W

    2006-01-05

    By combining the Sloan Digitized Sky Survey Third Data Release quasar list with the VLA FIRST survey, we have identified five objects having both broad absorption lines in their optical spectra and FR-II radio morphologies. We identify an additional example of this class from the FIRST Bright Quasar Survey, J1408+3054. Including the original FR-II-BAL object, J1016+5209, brings the number of such objects to eight. These quasars are relatively rare; finding this small handful has required the 45,000-large quasar sample of SDSS. The FR-II-BAL quasars exhibit a significant anti-correlation between radio-loudness and the strength of the BAL features. This is easily accounted for by the evolutionary picture in which quasars emerge from cocoons of BAL-producing material which stifle the development of radio jets and lobes. There is no such simple explanation for the observed properties of FR-II-BALs in the unification-by-orientation model of quasars. The rarity of the FR-II-BAL class implies that the two phases do not coexist for very long in a single quasar, perhaps less than 10{sup 5} years, with the combined FR-II, high ionization broad absorption phase being even shorter by another factor of 10 or more.

  17. Thermodynamic optimization of irreversible refrigerators

    Highlights: • Dimensionless equation that links COP, entropy rate variation and heat exchange. • Maximum COP as function of parameter controlling thermal exchanges. • Application at irreversible vapor compression refrigerator based on literature data. • Results show the analysis is useful in diagnostic and designing of refrigerators. - Abstract: An irreversible inverse cycle, operating at steady state conditions with finite thermal capacity heat sources, is analyzed in order to obtain an expression for the coefficient of performance accounting for the Second Law. Some dimensionless parameters are proposed to link the entropy variation rate and the temperature differences at the heat exchangers to the cycle efficiency. A maximum for efficiency appears when a parameter depending only on the temperature of the inlet streams at each heat exchanger is used. The influence of dimensionless parameters and irreversibilities on the maximum cycle efficiency is analyzed. A graphical analysis, based on data from literature, is presented to show the use of this thermodynamic optimization criteria in design and verification process of refrigerators

  18. Effect of cooling charge air on the gas turbine performance and feasibility of using absorption refrigeration in the “Kelanitissa” power station, Sri Lanka

    Kodituwakku, Dinindu

    2014-01-01

    One of the drawbacks of the gas turbine is that performance drops rapidly when ambient air temperature increases. This is a major drawback for gas turbines operated in a tropical country like Sri Lanka. In Colombo, commercial capital of Sri Lanka where this study was carried out, the ambient temperature typically varies between 25 0C and 32 0C.   The Kelanitissa gas turbine plant has single shaft gas turbines (GE MS5001 R) operated in open cycle which use diesel as fuel (designed for dual fue...

  19. Heat Pump Cycle Performance Analysis and Flammability Study of the CO2/DME Mixture Refrigerant%CO2/DME混合工质热泵循环性能分析及可燃性研究

    刘学武; 覃旭松; 杜永强; 关西文; 陈申

    2015-01-01

    The drying process is energy saving, efficient and environmental friendly. For solving the problem of high pressure in the transcritical CO2 heat pump cycle, the system of a transcritical heat pump drying cycle with an alternative refrigerant CO2/DME for CO2 is proposed. The performance of the system at different mass fractions of CO2 and DME in the mixtures is theoretically calculated and compared to the pure CO2. For the flammability of the DME, the standard test method ASTM E681-09 for concentration limits of flammability of chemicals was made. The results indicated that, at a certain mass ratio of the mixture refrigerant, there is a optimum pressure for the system. At the low concentration of DME, the mixture refrigerant CO2/DME has optimum performance with a mass ratio of 90/10. With the increasing of DME concentration, the COPh deceases slightly and then increases continually. With the mixture refrigerant CO2/DME has a mass ratio of 90/10, the optimized high side pressure of the transcritical CO2/DME decreased by 23 percent verse the pure CO2 heat pump cycle and the heating coefficient of performance (COPh) is increased by about 3.1 percent. DME flammability deceases as the CO2 added. The critical suppression explosion ratio point is reached at a volume ratio (CO2/DME) of 7.2. When the volume ratio larger than the critical point, the mixture refrigerant will not get explosion no matter how much air is added. It can be safely used.%针对跨临界CO2热泵循环压力高的问题,提出了以CO2/DME混合制冷剂替代纯CO2制冷剂的跨临界热泵循环系统。通过理论计算了不同配比下系统循环性能,并与纯CO2工质性能进行对比;为解决DME可燃性问题,实验测试并研究了混合工质爆炸极限。研究结果表明:在确定的混合工质配比下,系统存在最优压力使COPh最大;随DME质量比的增加,系统最优压力下降,而COPh先小幅下降而后持续增加;CO2/DME 质量配比在90

  20. In situ characterization of few-cycle laser pulses in transient absorption spectroscopy

    Blättermann, Alexander; Kaldun, Andreas; Ding, Thomas; Stooß, Veit; Laux, Martin; Rebholz, Marc; Pfeifer, Thomas

    2016-01-01

    Attosecond transient absorption spectroscopy has thus far been lacking the capability to simultaneously characterize the intense laser pulses at work within a time-resolved quantum-dynamics experiment. However, precise knowledge of these pulses is key to extracting quantitative information in strong-field highly nonlinear light-matter interactions. Here, we introduce and experimentally demonstrate an ultrafast metrology tool based on the time-delay-dependent phase shift imprinted on a strong-field driven resonance. Since we analyze the signature of the laser pulse interacting with the absorbing spectroscopy target, the laser pulse duration and intensity are determined in situ. As we also show, this approach allows for the quantification of time-dependent bound-state dynamics in one and the same experiment. In the future, such experimental data will facilitate more precise tests of strong-field dynamics theories.

  1. Thermo-refrigerating machineries. Classification; Machines thermofrigorifiques. Classification

    Duminil, M. [Association Francaise du Froid (AFF), 75 - Paris (France)

    2002-07-01

    Thermo-refrigerating systems transfer the heat extracted from a cold source towards a heat source and consume thermal energy from a third source. This article proposes a classification of thermo-refrigerating systems in three categories: the systems with a changing state working fluid (physical change of the refrigerant: dissociable systems, integrated systems (ejection systems, sorption systems); chemical change of the refrigerant), the systems where the working fluid stays in the same physical state (dissociable systems (Brayton, Siemens, Stirling and Ericsson cycles), integrated systems (Vuilleumier cycle systems, thermochemical systems)) and the other systems (Seebeck thermoelectric generator with Peltier effect modules). Dissociable thermo-refrigerating systems are made of the grouping of two separate thermal machines: a thermal engine and a mechanical-refrigerating machine. (J.S.)

  2. Steady state simulation of a double-effect steam absorption chiller

    Ahmed, M.S.A.M.S.; Gilani, S.I.U.H. [Universiti Teknologi Petronas, Tronoh, Perak (Malaysia). Dept. of Mechanical Engineering

    2011-07-01

    Absorption cooling systems have become increasingly popular in recent years from the viewpoint of energy and environment. Despite a lower coefficient of performance (COP) as compared to the vapor compression, absorption refrigeration systems are attractive for using inexpensive waste heat, solar, geothermal or biomass energy sources for which the cost of supply is negligible in many cases. In addition absorption refrigeration uses natural substances which do not contribute towards ozone depletion and global warming. Owing to the serious environmental problems and the price of the traditional energy resources, the use of industrial waste heat or renewable energy as the driving force for vapor absorption cooling systems is continuously increasing. A steady-state model is developed to predict the performance of an absorption refrigeration system using LiBr-water as working pair. Each component of the cycle is modelled based on mass and energy balances. The design point parameters are determined. The refrigeration effect, coefficient of performance and load factor are analyzed for different heat input. Simulation is carried out and the results are compared with actual data and showed good agreement.

  3. Simulation Model for Dynamic Operation of Double-Effect Absorption Chillers

    Ahmed Mojahid Sid Ahmed Mohammed Salih

    2014-07-01

    Full Text Available The development in the field of refrigeration and air conditioning systems driven by absorption cycles acquired a considerable importance recently. For commercial absorption chillers, an essential challenge for creating chiller model certainly is the shortage of components technical specifications. These kinds of specifications are usually proprietary for chillers producers. In this paper, a double-effect parallel-flow-type steam absorption chiller model based on thermodynamic and energy equations is presented. The chiller studied is Lithium bromide-water with capacity of 1250 RT (Refrigeration Tons. The governing equations of the dynamic operation of the chiller are developed. From available design information, the values of the overall heat transfer coefficients multiplied by the surface area are computed. The dynamic operation of the absorption chiller is simulated to study the performance of the system. The model is able to provide essential details of the temperature, concentration, and flow rate at each state point in the chiller.

  4. Generalized Performance Characteristics of Refrigeration and Heat Pump Systems

    Mahmoud Huleihil; Bjarne Andresen

    2010-01-01

    A finite-time generic model to describe the behavior of real refrigeration systems is discussed. The model accounts for finite heat transfer rates, heat leaks, and friction as different sources of dissipation. The performance characteristics are cast in terms of cooling rate (r) versus coefficient of performance (w). For comparison purposes, various types of refrigeration/heat pump systems are considered: the thermoelectric refrigerator, the reverse Brayton cycle, and the reverse Rankine ...

  5. Energy Absorption in a Load-Unload Cycle of Knee Implant Using Fractal Model of Rough Surfaces

    Hodaei, Mohammad; Farhang, Kambiz

    2016-05-01

    Roughness measurement of knee implant surfaces is investigated. The study of roughness measurement show that the topography of knee implant surface is multi-scale and surface spectra follows a power law behavior. A magnification of rough surface topography implies that there is no difference between original and magnified profile of implant surface. For implant surface, statistical parameters such as variance of height, curvature, and slope are found to be scale-dependent. Fractal representation of implant surface shows that the size-distribution of the multi-scale contacts spots follows a power law and is characterized by the fractal dimension of implant surface. Fractal surface description of the rough surfaces of knee implant is used to obtain force-displacement relationship of the contact force. Using an approximate function through the fusion of two piecewise functions, energy absorption of a knee implant in a single cycle of load-unload is obtained.

  6. Maximum practical efficiency of helium temperature refrigerators

    An ideal refrigerator using a perfect gas working fluid is defined which gives the efficiency of a refrigerator as a function of compressor and expander efficiency, heat exchanger temperature difference, and heat exchanger pressure drop. Although not suited to detailed hardware design, this approach clearly relates the overall cycle efficiency to component efficiencies. In contrast, computer studies of specific cycles using real fluid properties are usually such that the details tend to overshadow major trends. The results of the study show that in an efficient cycle the major losses are in the compressor and the cold end expansion device. For current compressor and expander efficiencies the maximum practical helium temperature refrigerator efficiency is about 37% of Carnot. (author)

  7. The absoption refrigerator as a thermal transformer

    Herrmann, Friedrich

    2008-01-01

    The absorption refrigerator can be considered a thermal transformer, i.e. a device that is analogous to the electric transformer. The analogy is based on a correspondence between the extensive quantities entropy and electric charge and that of the intensive variables temperature and electric potential.

  8. Defrost Temperature Termination in Supermarket Refrigeration Systems

    Fricke, Brian A [ORNL; Sharma, Vishaldeep [ORNL

    2011-11-01

    The objective of this project was to determine the potential energy savings associated with implementing demand defrost strategies to defrost supermarket refrigerated display case evaporators, as compared to the widely accepted current practice of controlling display case defrost cycles with a preset timer. The defrost heater energy use of several representative display case types was evaluated. In addition, demand defrost strategies for refrigerated display cases as well as those used in residential refrigerator/freezers were evaluated. Furthermore, it is anticipated that future work will include identifying a preferred defrost strategy, with input from Retail Energy Alliance members. Based on this strategy, a demand defrost system will be designed which is suitable for supermarket refrigerated display cases. Limited field testing of the preferred defrost strategy will be performed in a supermarket environment.

  9. Performance analysis of a triple-effect absorption cooling cycle using aqueous (lithium, potassium, sodium) nitrate solution as a working pair

    A triple-effect absorption cooling cycle using aqueous (lithium, potassium, sodium) nitrate solution (Alkitrate) as a working fluid in the high temperature stage is simulated in this work. This cycle takes advantage of the thermal potential of high temperature heat sources and has a configuration consisting of a H2O/LiBr double-effect cycle coupled with a single-effect cycle that uses Alkitrate as a working fluid. Heat is exchanged between the two cycles by thermal fluids which flow in the external circuits. The conventional working fluid H2O/LiBr suffers from serious problems of corrosion and thermal decomposition at temperatures of over 180 °C, which restricts its use in the high temperature components of a triple-effect absorption cooling cycle. At the nominal operating conditions selected, namely a heat source temperature TH of 250 °C and a cooling-water temperature TC of 30 °C the coefficient of performance achieved with the Alkitrate topping cycle is 1.73. The correct operation of the cycle is demonstrated by drawing the cycle in the Dühring diagram, where the safety margin for the crystallization of the working fluid is adhered to. Results show that the Alkitrate triple-effect cycle has a slightly higher efficiency as compared to the H2O/LiBr triple-effect cycle at generator temperatures of over 180 °C. Moreover, the practical operation of a H2O/LiBr triple-effect cycle at temperatures higher than 180 °C suffers from the above mentioned problems related to the thermal stability and corrosion of the working pair. - Highlights: • A triple-effect absorption cooling cycle using Alkitrate as a working pair is simulated for high temperature heat sources. • The cycle configuration consists of a H2O/LiBr DE cycle coupled with a SE cycle using Alkitrate as a working fluid. • The Alkitrate TE cycle has a slightly higher COP compared to H2O/LiBr TE cycle at generator temperatures of over 180 °C. • The Alkitrate triple-effect cycle represents a

  10. Design of Accelerated Fatigue Tests for Flame Free Refrigeration Fittings

    Wilson, Michael; Bowers, Chad D.

    2014-01-01

    Refrigerant leakage from failed braze joints is a multi-billion dollar problem for the global HVAC&R industry. Leaks are typically caused due to mechanical fatigue from extreme pressure cycling, temperature cycling including exposure to freeze/thaw cycles, or vibrational wear induced from rotating electrical machinery. Three tests to accelerate mechanical fatigue were devised to simulate real world extreme conditions to determine possible failure modes of refrigerant components. The first tes...

  11. Modeling water/lithium bromide absorption chillers in ASPEN Plus

    Highlights: → Single- and double-effect water/lithium bromide absorption chiller designs are numerically modeled using ASPEN. → The modeling procedure is described and the results are compared to published modeling data to access prediction accuracy. → Predictions for the single- and double-effect designs are within 3% and 5%, respectively of published data for all cycle parameters of interest. → The absorption cycle models presented allow investigation of using absorption chillers for waste heat utilization in the oil and gas industry. -- Abstract: Absorption chillers are a viable option for providing waste heat-powered cooling or refrigeration in oil and gas processing plants, thereby improving energy efficiency. In this paper, single- and double-effect water/lithium bromide absorption chiller designs are numerically modeled using ASPEN. The modeling procedure is described and the results are compared to published modeling data to access prediction accuracy. Predictions for the single- and double-effect designs are within 3% and 5%, respectively of published data for all cycle parameters of interest. The absorption cycle models presented not only allow investigation into the benefits of using absorption chillers for waste heat utilization in the oil and gas industry, but are also generically applicable to a wide range of other applications.

  12. Recent evolutions of refrigerating machineries and heat pumps; Evolutions recentes des machines a froid et thermopompes

    NONE

    1997-12-31

    This book of proceedings reports on 10 papers (or series of transparencies) concerning some recent developments about refrigerating machineries and heat pumps as used in space heating, air-conditioning and industrial refrigeration. Various aspects are developed: thermodynamic cycles, thermal performances, dimensioning, modeling, refrigerants substitution, design of flanged exchangers, compressors etc.. (J.S.)

  13. About Solar Refrigeration

    Laura Coroiu

    2008-05-01

    Full Text Available This paper has the purpose to unfold the results of all researches which proved before that the solar energy constitutes itself as an ideal resource for heating application that necessitate lower temperature,e.g. the heating of a certain space or the preparation ofthe domestic hot water. The refrigeration systems, which are based on the nontoxic refrigerants for the environment, offer a sustained advantage when compared to the other types of the refrigerants. But, whichever might be the case, the use of the energy associated to the operation of the refrigeration system and with the impact that it has upon the environment, as well as the association with its production and distribution, have often a bigger importance than the selection of the refrigerant. In order to minimize the impact which the operation of the refrigeration systems exerts upon the environment, it is recommended that there should be checked all thepossibilities of using a pure source of energy.

  14. Exergy analyses of an endoreversible closed regenerative Brayton cycle CCHP plant

    Bo Yang, Lingen Chen, Fengrui Sun

    2014-01-01

    An endoreversible closed regenerative Brayton cycle CCHP (combined cooling, heating and power) plant coupled to constant-temperature heat reservoirs is presented using finite time thermodynamics (FTT). The CCHP plant includes an endoreversible closed regenerative Brayton cycle, an endoreversible four-heat-reservoir absorption refrigerator and a heat recovery device of thermal consumer. The heat-resistance losses in the hot-, cold-, thermal consumer-, generator-, condenser-, evaporator- and ab...

  15. Evaluation of zeotropic refrigerants based on nonlinear relationship between temperature and enthalpy

    ZHAO; Li

    2006-01-01

    In order to evaluate cycling characters of zeotropic refrigerants in air-conditioning operation, and to reveal distribution rules of temperature difference between refrigerants and heat transfer fluids in condenser and evaporator, theoretical researches were carried out based on nonlinear relationship between temperature and enthalpy in period of refrigerants' phase change. Firstly, a phase changing model of refrigerants was built, and refrigerants state parameters were decided in the air-conditioning operation.Secondly, the state equation of refrigerants was applied for computing relationship between temperature and enthalpy, else based on some suppositions, temperature differences between 15 sorts of refrigerants and heat-transfer fluids were gotten too. Through concluding those temperature differences changing in condenser and evaporator, some rules were found. Lastly, after calculating and comparing the additive exergy loss among15 sorts of refrigerants, which resulted from the changing of temperature difference, their cycling characters evaluation were presented.

  16. About Solar Refrigeration

    Laura Coroiu; Helga Silaghi; Adriana Grava; Pantea, M.

    2008-01-01

    This paper has the purpose to unfold the results of all researches which proved before that the solar energy constitutes itself as an ideal resource for heating application that necessitate lower temperature,e.g. the heating of a certain space or the preparation ofthe domestic hot water. The refrigeration systems, which are based on the nontoxic refrigerants for the environment, offer a sustained advantage when compared to the other types of the refrigerants. But, whichever might be the case,...

  17. Cooling load and COP optimization of an irreversible Carnot refrigerator with spin-1/2 systems

    Xiaowei Liu, Lingen Chen, Feng Wu, Fengrui Sun

    2011-01-01

    A model of an irreversible quantum refrigerator with working medium consisting of many non-interacting spin-1/2 systems is established in this paper. The quantum refrigeration cycle is composed of two isothermal processes and two irreversible adiabatic processes and is referred to as a spin quantum Carnot refrigeration cycle. Expressions of some important performance parameters, such as cycle period, cooling load and coefficient of performance (COP) for the irreversible spin quantum Carnot re...

  18. Natural refrigerants. Future heat pumps for district heating; Naturliga koeldmedier. Framtida vaermepumpar foer fjaerrvaerme

    Ingvarsson, Paul; Steen Ronnermark, Ingela [Fortum Teknik och Miljoe AB, Stockholm (Sweden); Eriksson, Marcus [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Chemical Engineering and Environmental Science

    2004-01-01

    improvement in components, system and external preconditions. In the future it might be more interesting to use turbine driven heat pumps instead of electric motors. The absorption process is not considered to be an alternative to replace present heat pumps, but there is a certain niche where heat source and driving energy, considering temperature levels, are more suitable for district heating. A technique that seems to be an alternative to the compression cycle is a combination of compression and absorption. Using the media pair water and ammonia might be an interesting solution and should be compared to the alternative using carbon dioxide. A further study is recommended on this subject.

  19. ARTI refrigerant database

    Calm, J.M. [Calm (James M.), Great Falls, VA (United States)

    1998-08-01

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufactures and those using alternative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air-conditioning and refrigeration equipment. The complete documents are not included, though some may be added at a later date. The database identifies sources of specific information on many refrigerants including propane, ammonia, water, carbon dioxide, propylene, ethers, and others as well as azeotropic and zeotropic blends of these fluids. It addresses lubricants including alkylbenzene, polyalkylene glycol, polyolester, and other synthetics as well as mineral oils. It also references documents addressing compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits. Incomplete citations or abstracts are provided for some documents. They are included to accelerate availability of the information and will be completed or replaced in future updates.

  20. ARTI refrigerant database

    Calm, J.M.

    1997-02-01

    The Refrigerant Database is an information system on alternative refrigerants, associated lubricants, and their use in air conditioning and refrigeration. It consolidates and facilitates access to property, compatibility, environmental, safety, application and other information. It provides corresponding information on older refrigerants, to assist manufacturers and those using alterative refrigerants, to make comparisons and determine differences. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air-conditioning and refrigeration equipment. The complete documents are not included, though some may be added at a later date. The database identifies sources of specific information on various refrigerants. It addresses lubricants including alkylbenzene, polyalkylene glycol, polyolester, and other synthetics as well as mineral oils. It also references documents addressing compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits. Incomplete citations or abstracts are provided for some documents. They are included to accelerate availability of the information and will be completed or replaced in future updates.

  1. Exergy analysis of gas turbine trigeneration system for combined production of power heat and refrigeration

    Khaliq, Abdul [Department of Mechanical Engineering, Faculty of Engineering and Technology, Jamia Millia Islamia, New Delhi 110025 (India)

    2009-05-15

    A conceptual trigeneration system is proposed based on the conventional gas turbine cycle for the high temperature heat addition while adopting the heat recovery steam generator for process heat and vapor absorption refrigeration for the cold production. Combined first and second law approach is applied and computational analysis is performed to investigate the effects of overall pressure ratio, turbine inlet temperature, pressure drop in combustor and heat recovery steam generator, and evaporator temperature on the exergy destruction in each component, first law efficiency, electrical to thermal energy ratio, and second law efficiency of the system. Thermodynamic analysis indicates that exergy destruction in combustion chamber and HRSG is significantly affected by the pressure ratio and turbine inlet temperature, and not at all affected by pressure drop and evaporator temperature. The process heat pressure and evaporator temperature causes significant exergy destruction in various components of vapor absorption refrigeration cycle and HRSG. It also indicates that maximum exergy is destroyed during the combustion and steam generation process; which represents over 80% of the total exergy destruction in the overall system. The first law efficiency, electrical to thermal energy ratio and second law efficiency of the trigeneration, cogeneration, and gas turbine cycle significantly varies with the change in overall pressure ratio and turbine inlet temperature, but the change in pressure drop, process heat pressure, and evaporator temperature shows small variations in these parameters. Decision makers should find the methodology contained in this paper useful in the comparison and selection of advanced heat recovery systems. (author)

  2. Construction of a 2 kW/4 K Helium Refrigerator for HT-7U

    白红宇; 毕延芳; 王金荣; 庄明; 朱平; 张启勇; 盛林海

    2002-01-01

    Superconducting magnets of toroidal field (TF) and poloidal field (PF) of HT-7U tokamak are all made of NbTi/Cu Cable-in-Conduit Conductor (CICC), and cooled with a forced flow supercritical helium of 3.8 K. A helium refrigerator with an equivalent capacity of 2 kW/4 K will be constructed. This paper presents the design of the helium refrigerator process, the thermodynamics of the refrigeration cycle and the refrigerator equipments.

  3. Modeling and simulation of the operation of a rotary magnetic refrigerator

    Gonin, Cyrill; Kawanami, Tsuyoshi; Kitanovski, Andrej; Egolf, Peter W.; Vuarnoz, Didier

    2015-01-01

    Magnetic refrigeration is a new environmentally benign technology and a promising alternative to conventional vapor-cycle refrigeration. The household refrigerator without a freezing compartment shows very good prospects for a successful application. This article starts with the general principle of magnetic refrigeration. An example of a magnet assembly is proposed and the corresponding magnetic flux lines are evaluated with a three-dimensional finite-element method (FEM). The maximum specif...

  4. Construction of a 2 kw/4 K helium refrigerator for HT-7U

    Superconducting magnets of toroidal field (TF) and poloidal field (PF) of HT-7U tokamak are all made of NbTi/Cu Cable-in-Conduit Conductor (CICC), and cooled with a forced flow supercritical helium of 3.8 K. A helium refrigerator with an equivalent capacity of 2 kW/4 K will be constructed. The author presents the design of the helium refrigerator process, the thermodynamics of the refrigeration cycle and the refrigerator equipment

  5. CO2LD: an educational innovation project for advanced vocational training in refrigeration

    Cabello López, Ramon; Llopis Domenech, Rodrigo; Sánchez García-Vacas, Daniel; Torrella Alcaraz, Enrique; Patiño Pérez, Jorge

    2013-01-01

    Refrigeration is one of the technology sectors that has suffered the most changes in the last twenty years, because of the negative impact of the fluids used in the refrigeration cycles, i.e., refrigerants, due to their impact on the ozone layer and their contribution to global warming. As a result of their negative effects, the European Union has established several directives to restrict the use of refrigerant fluids, and the sector therefore needs to adapt to the new regulations. This proc...

  6. CO2LD: An innovation educational project for High Degree Professional Training in Refrigeration.

    Sánchez, Daniel; Llopis Rodrigo; Patiño, Jorge; Cabello, Ramón; Torrella Alcaraz, Enrique

    2013-01-01

    Refrigeration is one of the technology sectors that has sufered the most changes in the last twenty years, because of the negative impact of the fuids used in the refrigeration cycles, i.e., refrigerants, due to their impact on the ozone layer and their contribution to global warming. As a result of their negative efects, the European Union has established several directives to restrict the use of refrigerant fuids, and the sector therefore needs to adapt to the new regulations. ...

  7. CO2LD: An innovation educational project for High Degree Professional Training in Refrigeration

    Ramon Cabello Lopez; Rodrigo Llopis Domenech; Daniel Sanchez García-Vacas; Enrique Torrella Alcaraz; Jorge Patiño Pérez

    2013-01-01

    Refrigeration is one of the technology sectors which has suffered most changes in the last twenty years, because of the negative impact of the fluids used in the refrigeration cycles, the refrigerants, due to their impact in the ozone layer and the promotion of the global warming. Due to the negative impacts of the fluids, the European Union has established several directives to restrict the use of refrigerant fluids, causing the need of adaptation of the sector to the new regulations. The ad...

  8. 一种新型混合吸收式制冷循环的性能分析%THE PERFORMANCE OF A NOVEL MIXED ABSORPTION REFRIGERATION CYCLE

    万忠民; 舒水明

    2003-01-01

    该文提出一种新型吸收式循环,可以较好利用太阳能实现制冷,解决传统吸收式系统在利用太阳能实现制冷时存在的弊端.这种新型混合式吸收式制冷循环在两级吸收式循环的基础上增设了一个附加高压发生器,发现影响系统COP值的因素主要是LiBr溶液浓度与低压发生器中的压力.在溶液浓度与压力的允许范围内时,新型循环的高压发生器再生出LiBr溶液与低压吸收器的吸收后的溶液混合,提高高压吸收器吸收剂浓度从而减小其压力.本文主要分析了混合吸收式制冷循环的各种性能特性,得出影响系统热力系数(COP)可达0.55,驱动热源的可利用温差最高可达35℃.

  9. Simulation of a refrigerant evaporator

    Vandermeer, Jakob Stefanus

    A computer model for the design and optimization of the compressor refrigeration cycle especially with respect to dynamic behavior was developed. A steady state version was also developed. The model describing the refrigerant is divided into the evaporation and superheating regions. A mechanism based on empirics corrects the model for the influence of transportation times in the evaporation region. The mass balance of the refrigerant in the superheat region is regarded as quasi-static, because of the small mass of the vapor. The energy balance accounts for a distributed model and is represented by the steady state solution of the partial differential equation which describes this area for the steady conditions. A correction for the dynamical effects was added to this solution, for all influencing parameters, according to the analytical dynamic solution for the case of the evaporation temperature as input parameter. The expansion device model was worked out for the usual type of device in combination with a dry evaporator, the thermostatic expansion valve. Validation tests are described.

  10. Performance Comparison of Single-Stage and Cascade Refrigeration Systems Using R134a as the Working Fluid

    HOŞÖZ, Murat

    2005-01-01

    This study presents an experimental comparison of single-stage and cascade vapour-compression refrigeration systems using R134a as the refrigerant. The experimental plants employ a vapour-compression refrigeration cycle serving as a base unit, a cooling tower and another vapour-compression refrigeration cycle serving as a higher-temperature unit in the cascade operation. In the single-stage operation the condenser of the base unit was connected to the cooling tower, whereas in the ca...

  11. EXERGETIC PERFORMANCE OF A DOMESTIC REFRIGERATOR USING R12 AND ITS ALTERNATIVE REFRIGERANTS

    BUKOLA O. BOLAJI

    2010-12-01

    Full Text Available Production and use of R12 and other chlorofluorocarbon refrigerants will be prohibited completely all over the world in the year 2010 due to their harmful effects on the earth’s protective ozone layer. Therefore, in this study, the exergetic performance of a domestic refrigerator using two environment-friendly refrigerants (R134a and R152a was investigated and compared with the performance of the system when R12 (an ozone depleting refrigerant was used. The effects of evaporator temperature on the coefficient of performance (COP, exergy flow destruction, exergetic efficiency and efficiency defect in the four major components of the cycle for R12, R134a and R152a were experimentally investigated. The results obtained showed that the average COP of R152a was very close to that of R12 with only 1.4% reduction, while 18.2% reduction was obtained for R134a in comparison with that of R12. The highest average exergetic efficiency of the system (41.5% was obtained using R152a at evaporator temperature of -3.0oC. The overall efficiency defect in the refrigeration cycle working with R152a is consistently better (lower than those of R12 and R134a. Generally, R152a performed better than R134a in terms of COP, exergetic efficiency and efficiency defect as R12 substitute in domestic refrigeration system.

  12. Cryogenic mixed refrigerant processes

    Venkatarathnam, Gadhiraju

    2010-01-01

    Teaches the need for refrigerant mixtures, the type of mixtures that can be used for different refrigeration and liquefaction applications, the different processes that can be used and the methods to be adopted for choosing the components of a mixture and their concentration for different applications.

  13. Theoretical thermodynamics analysis of cooling cycle bu advanced gas absorption using solar energy; Analisis teorico-experimental de un ciclo de refrigeracion por absorcion avanzado gax, operando con energia solar

    Gomez, V. E.; Vidal, A. S.; Garcia, C. A.; Garcia-Valladares, O.; Best, R. B.; Hernandez, J. G.; Velazquez, N. L.

    2004-07-01

    In this article a solar system of refrigeration by absorption with heat exchange generator absorber (GAX) was analyzed. A theoretical thermodynamic analysis of the energetic behavior of the GAX absorption system was made. Experimental results were obtained with generation temperatures of 190 and 220 C, the evaporation temperature was set at 9 C and temperatures of cooling fluids (air and water) were set at 30 C and 28 C, respectively. It was possible to appreciate that the GAX effect decrease whether absorber, type falling film, is operated in option of parallel flow and it was increased when the absorber was operated in option of counterflow. (Author)

  14. The leiden dilution refrigerator

    In march 1971, the author constructed the first version of a new type of 3He-4He dilution refrigerator through which, in contrast with the conventional dilution refrigerator, 4He instead of 3He is circulated. It is possible to keep the 4He circulation entirely at low temperatures, by using the fountain effect in superfluid 4He. The most important advantage of this refrigerator is that the precooling of nearly pure 3He simply takes place in one (spiralled or straight) capillary through which both liquid helium phases flow in opposite directions, driven by the force of gravity. Heat exchangers with their often complicated technical constructions are avoided. The lowest temperature that can be achieved in the refrigerator is about 5 mK. In this thesis, experiments with and a thermodynamic analysis of this refrigerator are described

  15. ARTI Refrigerant Database

    Calm, J.M.

    1992-04-30

    The Refrigerant Database consolidates and facilitates access to information to assist industry in developing equipment using alternative refrigerants. The underlying purpose is to accelerate phase out of chemical compounds of environmental concern. The database provides bibliographic citations and abstracts for publications that may be useful in research and design of air- conditioning and refrigeration equipment. The complete documents are not included, though some may be added at a later date. The database identifies sources of specific information on R-32, R-123, R-124, R- 125, R-134a, R-141b, R142b, R-143a, R-152a, R-290 (propane), R-717 (ammonia), ethers, and others as well as azeotropic and zeotropic blends of these fluids. It addresses polyalkylene glycol (PAG), ester, and other lubricants. It also references documents addressing compatibility of refrigerants and lubricants with metals, plastics, elastomers, motor insulation, and other materials used in refrigerant circuits.

  16. Optimal performance of a quantum Otto refrigerator

    Abah, Obinna; Lutz, Eric

    2016-03-01

    We consider a quantum Otto refrigerator cycle of a time-dependent harmonic oscillator. We investigate the coefficient of performance at maximum figure of merit for adiabatic and nonadiabatic frequency modulations. We obtain analytical expressions for the optimal performance both in the high-temperature (classical) regime and in the low-temperature (quantum) limit. We moreover analyze the breakdown of the cooling cycle for strongly nonadiabatic driving protocols and derive analytical estimates for the minimal driving time allowed for cooling.

  17. Acoustic recovery of lost power in pulse tube refrigerators

    In an efficient Stirling-cycle cryocooler, the cold piston or displacer recovers power from the gas. This power is dissipated into heat in the orifice of an orifice pulse tube refrigerator, decreasing system efficiency. Recovery of some of this power in a pulse tube refrigerator, without sacrificing the simplicity and reliability inherent in a system with no cold moving parts, is described in this paper. In one method of such power recovery, the hot ends of both the regenerator and the pulse tube are connected to the front of the piston driving the refrigerator. Experimental data is presented demonstrating this method using a thermoacoustic driver instead of a piston driver. Control of time-averaged mass flux through the refrigerator is crucial to this power recovery, lest the refrigerator close-quote s cooling power be overwhelmed by a room-temperature mass flux. Two methods are demonstrated for control of mass flux: a barrier method, and a hydrodynamic method based on turbulent irreversible flow. At -55 degree C, the refrigerator provided cooling with 9% of the Carnot coefficient of performance. With straightforward improvements, similar refrigerators should achieve efficiencies greater than those of prior pulse tube refrigerators and prior standing-wave thermoacoustic refrigerators, while maintaining the advantages of no moving parts. copyright 1999 Acoustical Society of America.

  18. Potential of the tractor-trailer and container segments as entry markets for a proposed refrigeration technology

    Smith, S.A.; Davis, L.J.; Garrett, B.A.

    1987-05-01

    The refrigerated trailer and container segments of the transportation industry are evaluated as potential entry markets for a proposed absorption refrigeration technology. To perform this analysis the existing transportation refrigeration industry is characterized; this includes a description of the current refrigeration technology, rating systems, equipment manufacturers, maintenance requirements, and sales trends. This information indicates that the current transportation refrigeration industry is composed of two major competitors, Thermo King and Carrier. In addition, it has low profit potential, some barriers to entry and low growth potential. Data are also presented that characterize the transportation refrigeration consumers, specifically, major groups, market segmentation, consumer decision process, and buying criteria. This consumer information indicates that the majority of refrigerated trailer consumers are private carriers, and that the majority of refrigerated container consumers are shipping companies. Also, these consumers are primarily interested in buying reliable equipment at a low price, and are quite satisfied with existing refrigeration equipment.

  19. Design and performance study of the active magnetic refrigerator for room-temperature application

    Zheng, Z.G.; Yu, H.Y.; Zhong, X.C.; Zeng, D.C.; Liu, Z.W. [School of Materials Science and Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640 (China)

    2009-01-15

    A room-temperature magnetic refrigerator, consisting of permanent magnet, active magnetic refrigeration (AMR) cycle bed, pumps, hydraulic circuit, active magnetic double regenerator cycle (AM2RC) and control subsystems, has been designed. The magnetic field is supplied by NdFeB permanent magnets. The AMR bed made by stainless steel 304 encloses gadolinium particles as the magnetic working substance. Each part of the refrigerator is controlled by the programmable controller. The different standard heat exchangers are employed to expel heat. The cycle performance of this self-designed facility is analyzed using Langevin theory. The results provide useful data for future design and development of room-temperature magnetic refrigeration. (author)

  20. The superfluid Stirling refrigerator, a new method for cooling below 0.5 K

    A new sub-Kelvin refrigerator, the superfluid Stirling cycle refrigerator, uses a working fluid of 3He-4He mixture in a Stirling cycle. The thermodynamically active components of the mixture are the 3He, which behaves like a Boltzmann gas, and the phonon-roton gas in the 4He. The superfluid component of the liquid is inert. Two refrigerators have been built, and temperatures of 340 mK have been achieved. (orig.)