Expansion Work Recovery Research Articles

A quasi-two-stage trans-critical CO2 heat pump with in-cycle thermal storage for performance enhancement

To decarbonise the heating sector, there is a strong demand for environmentally friendly and cost-effective heating technologies. Trans-critical CO2 heat pumps offer a sustainable alternative to traditional vapor compression cycles that rely on environmentally harmful synthetic refrigerants. However, a significant challenge within trans-critical CO2 heat pumps is their high throttling loss during expansion, leading to substantial flash gas production and subsequently higher recompression power consumption. In this paper, we apply our Flexible Heat Pump cycle concept to trans-critical CO2 heat pumps to address this issue. A thermal storage unit is introduced into a traditional trans-critical CO2 heat pump cycle to recover heat from the hot super-critical CO2 leaving the gas cooler during charging mode. Once it is fully charged, the stored heat is then used as a temporary heat source for the heat pump’s operation during the discharging mode. Since the recovered heat has a higher temperature than ambient. The resultant flexible trans-critical CO2 heat pump (FlexiCO2-HP) reduces throttling losses and the compressor’s power consumption, leading to a higher average COP (Coefficient of Performance). The obtained results of the FlexiCO2-HP are compared against a single-stage trans-critical CO2 heat pump. For gas cooler temperatures ranging from 35 °C to 60 °C and across various discharge pressures, its COP is potentially 10 % to 40 % higher than the standard cycle under ideal conditions. In addition, the proposed system demonstrates a lower optimal gas cooler pressure across different gas cooler temperatures. Furthermore, this study compares the FlexiCO2-HP with other trans-critical CO2 systems, including those with expansion work recovery and two-stage configurations. The results demonstrate that the FlexiCO2-HP offers improvements in COP for most conditions, though not all. It has the potential to achieve a comparable COP when compared with ejector-based and expander-based heat pumps or two-stage systems, but it is much simpler in design without introducing an extra expander or compressor.

Experimental performance comparison of various expansion devices for small-capacity subcritical R744 vapour-compression refrigeration units

The target of this study is to experimentally compare the performance of three different expansion devices for small-capacity subcritical R744 vapour-compression refrigeration units. The first considered expansion device was the conventional high-pressure expansion valve, which was selected as the baseline. The second assessed expansion device was a two-phase ejector for expansion work recovery whose refrigerant flow was modulated via the pulse-width modulation (PWM) strategy. Finally, the PWM approach was employed for controlling the refrigerant flow of the ejector motive nozzle while the refrigerant was not permitted to be drawn by the ejector suction nozzle. The results showed that the motive nozzle controlled via PWM effect offers similar effectiveness to a conventional high-pressure expansion valve in the subcritical regime. Furthermore, it was observed that the PWM ejector is able to control the high pressure effectively while increasing the coefficient of performance (COP) by up to 5.3 % without and by up to 7.9 % with overfed evaporator compared to the baseline in the transition regime. The results also showed that the installation of the conventional high-pressure expansion valve is not necessary. Finally, the yearly performance of the aforementioned expansion devices was assessed in five different locations, i.e., Athens (Greece), Phoenix (USA), New Delhi (India), Riyadh (Saudi Arabia) and Bangkok (Thailand). The outcomes revealed that the PWM ejector allows for a higher in yearly average COP (COPyearly avg) from 4.9 % (in Athens) to 11.8 % (in Bangkok) over the baseline.

Experimental investigation of a transcritical CO2 refrigeration system incorporating rotary gas pressure exchanger and low lift ejectors

Natural refrigerants like CO2 are playing a significant role in making refrigeration and heat pump systems climate-friendly by slowly phasing out the high global warming refrigerants like hydrofluorocarbons (HFCs). However, the efficiency of a transcritical CO2 refrigeration system declines significantly when the ambient temperature increases, primarily attributed to the high-pressure lift and the losses incurred during expansion. To remedy this issue, this paper presents a novel rotary gas pressure exchanger (PXG) device, which simultaneously achieves high differential pressure expansion work recovery and the “free compression” of the portion of the flash gas in a compact, rotary machine. For this, a PXG device is designed, fabricated, and tested to achieve free compression of CO2 over the entire differential pressure of approximately 70 bar between a receiver and a gas cooler. This is one of the highest free-pressure lift provided by any device to date in CO2 refrigeration. However, there is a small pressure loss of approximately 1–2 bar in the system due to viscous and inertia losses in the piping and in the PXG itself, which needs to be overcome by an external booster device. Results on a baseline PXG integrated system with two low lift booster compressors are presented, which show up to 60 bar free pressure lift and up to 18.2 % COP improvement provided by PXG. Additionally, key performance characteristics of the PXG, like the expansion work recovery, the mass boost ratio, direct fluid-to-fluid contact, and no pass-through operation are experimentally quantified. This work also presents a novel method to integrate two low lift ejectors with PXG to eliminate the need for separate low lift compressors. The low lift ejectors are designed, fabricated, and tested in-house, followed by their integration with the PXG device. A new type of transcritical CO2 refrigeration system is designed to integrate these low lift ejectors with PXG, and experiments are conducted at various evaporator thermal duties and gas cooler exit temperatures, simulating varying ambient temperature conditions. A novel control system to control the gas cooler pressure to optimal thermodynamic levels using PXG rotational speed is demonstrated experimentally. Further, automated control of high-pressure low lift ejector mass flow using an in-built needle design has been successfully demonstrated to optimise PXG mass boost performance. The LP low lift ejector achieved a successful pressure lift of 3.8 bar, and the HP low lift ejector showed a lift of 5.7 bar on the top of 42 bar free pressure lift provided by PXG for up to 5.8 kg/min mass flow delivered by free PXG compression. The results from this study demonstrate that the PXG device provides a significant energy efficiency improvement to the transcritical CO2 refrigeration system, and the novel low lift ejectors, when integrated with PXG, provide a successful method to maximise PXG’s thermodynamic potential.

A hydrate-based post-combustion capture system integrated with cold energy: Thermodynamic analysis, process modeling and energy optimization

Carbon capture is a crucial part of global warming mitigation. Carbon capture via clathrate hydrate is an attractive approach due to its high capture capacity, high carbon dioxide purity, water-based benign process, ease of recycling, and robustness to contaminants. In this work, we propose a two-stage hydrate-based carbon dioxide separation system integrated with cold energy for carbon capture from flue gases. A thermodynamic cycle consisting of two sub-cycles was constructed to simulate the process. Operating conditions were optimized within the range of 274.15–282.15 K and 0.1–28.04 MPa, resulting in the lowest electricity consumption of 2.22 MJ/kg CO2 with 95.24 mol% CO2 purity and 65.97 % CO2 recovery. A higher CO2 recovery rate can be achieved by recycling the residual gas of Sub-cycle 2. Gas compression to the high operating pressure (16.01 MPa) is the major contributor to electricity consumption. By incorporating 100 % expansion work recovery from the high-pressure gases, the electricity consumption can be reduced to 0.43 MJ/kg CO2 (i.e., 0.119 kWh/kg CO2). A more realistic scenario assuming 80 % compression/pumping efficiency and 90 % expansion work recovery gives an electricity consumption of 1.16 MJ/kg CO2 (i.e., 0.322 kWh/kg CO2), representing an energy penalty of 33.1 % for a coal-fired power plant. Future direction for further improvement could be a paradigm shift to hydrate process with thermodynamic promoters, which can potentially reduce the operation pressure by over 90 % and thus cut down the energy consumption dramatically. This work established a framework to simulate the hydrate-based carbon capture process, evaluated its minimum energy consumption and examined how operating conditions affect the separation performance. The results could offer valuable guidelines for the design and optimization of real hydrate-based carbon capture systems.

Thermodynamic analysis of rotary pressure exchanger and ejectors for CO2 refrigeration system

Natural refrigerant CO2 has become a viable choice for refrigeration units for land-based and offshore applications due to its environment-friendly nature and compactness. The CO2 transcritical cycle allows operating in colder climates and in elevated ambient temperature conditions and with significant heat recovery. However, the energy efficiency of the system suffers at higher heat rejection conditions mainly due to expansion losses. This work theoretically investigates and proposes the implementation of a new expansion work recovery device, a pressure exchanger (CO2-PX), for the transcritical CO2 cycle. The numerical models are developed in the Engineering Equation solver (EES) to compare the performance of CO2-PX configuration with standard booster-, parallel-, and ejector- configurations for various conditions. The analysis is carried out for the evaporation temperature of 0 ℃ and the gas cooler outlet temperature of 33 ℃ to 37 ℃. The results indicate that the coefficient of performance (COP) is improved by 17.7–23.5%, 16.3–20.3%, and 2.4–5.5% to the standard booster, parallel and ejector configurations, respectively, at the investigated conditions.

Experimental investigation of high-temperature heating in open-loop air cycle heat pump system utilizing compressed gas waste energy recovery

Recycling waste energy from compressed gases has consistently been a focal point in the field of energy conservation. This paper presents a novel open-loop air cycle heat pump system designed to recover waste energy from compressed gases. The system maintains stable operation and provide hot water above 80 °C even under extreme ambient temperatures (below −30 °C), thereby catering to diverse heating needs across a wide temperature spectrum. Experimental results show that, when the ambient temperature varies from 10 °C to −20 °C, the heating capacity and water temperature difference between inlet and outlet only decrease by 4.82% and 4.99% respectively, suggesting negligible impact. However, when water flow rate varies from 4 m3/h to 10 m3/h, the heating capacity marginally increases by 3.35% while the water temperature difference between inlet and outlet significantly decreases by 141.95%. Continuous increase of inlet water temperature Tw, in at 0.40 °C·min−1 results in an initial 10% decrease of heating capacity, following which the system automatically adjusts to another stable operational state of around 50 kW heating capacity. This transition has minimal effect on the water temperature difference between inlet and outlet and temperature rise rate of outlet water temperature. The expansion work recovery efficiency of turbine-compressor coupled module is approximately 90%.

Energy and Exergy Analysis of an Ejector Expansion Transcritical Carbon Dioxide Air Conditioning System

A carbon dioxide based transcritical air conditioning system integrated with an ejector is thermodynamically modeled and the system is simulated for different ambient conditions. Throughout the analysis, the isentropic efficiency of motive nozzle, suction nozzle and diffuser is assumed as 85% while the mixing takes place at constant pressure. A step-by-step iterative procedure is adopted to obtain the pressure lift and entrainment ratio. The present thermodynamic model is validated with the experimental results available in the open literature. Results were then compared to a conventional transcritical carbon dioxide system working between the same operating conditions. Results show a significant improvement of about 21% and more in system performance compared to a conventional system working under the same operating conditions. To justify the application of an ejector as an expansion work recovery device and to identify the component level exergy destruction rate, a comprehensive exergy analysis is implemented and the results show 20% reduction in total exergy destruction rate of the system, with an ejector.

Thermodynamic performance of the fractionated auto-cascade refrigeration cycle coupled with two-phase ejector using R1150/R600a at −80 °C temperature level

The auto-cascade refrigeration cycle (ACRC) is suitable for low temperature refrigeration fields. From the perspective of fractionation purification matching expansion work recovery, a fractionated auto-cascade refrigeration cycle coupled with the two-phase ejector (FACRC-TPE) using environmentally-friendly R1150/R600a is proposed in this paper. In the novel cycle, the two-phase ejector is substituted for the throttle valve at the liquid stream passage from the separator bottom to recover expansion work and cut down the energy consumption, while the fractionation heat exchanger is applied for purification of low boiling point component in the vapor stream from the separator top to boost the cycle exergy efficiency and achieve a refrigeration temperature below −80 °C. The energetic and exergetic analysis methods are used to evaluate and compare the performances of the three cycles, and comparisons of superiority and irreversibility of FACRC-TPE are also made with the unfractionated auto-cascade refrigeration cycle with the two-phase ejector (UACRC-TPE) and the fractionated auto-cascade refrigeration cycle (FACRC). The results show that the cooperative application of the fractionation heat exchanger coupled with the two-phase ejector not only significantly boosts COP of FACRC-TPE and obtains lower refrigeration temperature, but also cuts down the total exergy loss of FACRC-TPE. With R1150 mass fraction varying in the range of 0.29–0.48, the average COP of FACRC-TPE is 10.57% higher than that of UACRC-TPE, and is 15.18% higher than that of FACRC, whereas FACRC-TPE has a lower evaporator inlet temperature of −100.48 °C to −87.96 °C, as compared with UACRC-TPE. In addition, FACRC-TPE obtains the highest exergy efficiency of 32.23%, while the UACRC-TPE exergy efficiency of 26.99% is slightly higher than the FACRC exergy efficiency of 25.19%.

Performance analysis of dual ejector-expansion air source heat pump cycle with three-stage evaporation for cold region application

In the present study, a modified dual ejector-expansion heat pump cycle with three-stage evaporation has been proposed for air source heat pump applications in cold region. This cycle layout could lead to an improvement in cycle performance due to much expansion work recovery and better temperature variation matching between cooled air and refrigerant. The performance analyses of the proposed cycle and ejectors using refrigerant R290 have been conducted at different operating conditions. In addition, the performance characteristics of the cycle are compared to those of the baseline cycles using a conventional expansion device, as well as a single ejector and a single evaporator. Through thermodynamic analyses, it is found that the improvements in the coefficient of performance of the proposed cycle can reach up to 26.1% and 10.5%, respectively, as compared to the basic vapor-compression heat hump cycle and ejector-expansion heat hump cycle. The exergy destruction of the proposed cycle can be reduced by 28.6% and 13.6% than those of the other two basic cycles. In addition, the performance of ejectors under different operating conditions is studied. The pressure lift ratio of the ejector in the new cycle varies from 1.36 to 1.69, which shows 14.3%∼21.6% improvement compared to the basic ejector-expansion heat pump cycle. Overall, this paper confirms the performance advantages of the proposed new heat pump cycle and its potential application in an air-source heat pump system.

Energy analysis and performance comparison of transcritical CO2 supermarket refrigeration cycles

Using carbon dioxide as a refrigerant gains importance as a result of restrictions applied to high-GWP (Global Warming Potential) refrigerants. Although CO2 is an environment-friendly refrigerant, its low critical temperature and high operating pressure lead to high energy consumption, especially in commercial refrigeration. As a result, research and improvements are being made to reduce the energy consumption of transcritical CO2 refrigeration cycles. This paper presents thermodynamic analysis and pressure optimizations to obtain maximum performance for transcritical booster, parallel compression, and ejector expansion supermarket refrigeration cycles. Effects of different operation conditions were also investigated and cycles were compared to each other in terms of performance. It was obtained that up to 47% Coefficient of Performance (COP) improvement can be achieved using ejector expansion cycle with the help of expansion work recovery in the ejector. It was also shown that ejector expansion cycle outperforms other CO2-only cycles without ejector in all conditions.

A Parametric Study on the Effect of Mixing Chamber for Expansion Work Recovery CO2 Ejector

A Parametric Study on the Effect of Mixing Chamber for Expansion Work Recovery CO2 Ejector

Experimental investigation of a two-phase ejector installed into the refrigeration system for performance enhancement

In this paper, the performance enhancement of the two-phase ejector installed into the refrigeration system called an ejector-expansion refrigeration system (EERS) is investigated experimentally. A comparative performance of an ejector expansion refrigeration system (EERS) with a conventional vapour-compression refrigeration (VCRS) system is proposed. The main purpose is to demonstrate the ability to mitigate the throttling loss or to demonstrate the expansion work recovery in which the theoretical work is limited. The experimental test bench which can be operated with both VCRS and EERS is designed and built for investigations. It is designed to produce chilled water under various cooling loads which allows it to produce the desired cooling temperature for performance assessment. The condenser is cooled by the cooling water whose temperature can be controlled precisely. The test results indicate that the EERS gives better performance over the VCRS when the expansion pressure ratio must be large enough. Therefore, there is limitation of using the EERS for the expansion work recovery. The system COP can be increased by 5.3–12.7% when the cooling temperature is decreased from 12 to 2 °C. The pressure lift effect of the two-phase ejector causes a reduction in the compressor’s pressure ratio which results in a lower specific work and the refrigerant discharge temperature. This yields a longer life-time of the compressor and better lubrication. It is also found that the working condition has a significant impact on the ability to enhance the system performance of the two-phase ejector installed into the refrigeration system.

Thermodynamic Analysis of Air-Cycle Refrigeration Systems with Expansion Work Recovery for Compartment Air Conditioning

As a requirement for sustainable development, air-cycle refrigeration has received wide attention as a candidate for environmentally friendly air conditioning technology. In this study, the thermodynamic performance of air refrigeration cycles is investigated in compartment air conditioning. The effects of compressor efficiency, expander efficiency, ambient humidity, all-fresh-air supply and ambient pressure on the cycle performance are presented. The effects of compressor arrangement in the high-pressure cycle and the low-pressure cycle are compared. An open-loop high-pressure cycle has a larger COP than that of an open-loop low-pressure cycle but requires larger heat exchange. The performance of air refrigeration cycles with full fresh air is studied, and the influence of fresh air is discussed. Schemes for condensed water recirculation with wet compression are proposed, which can improve the COPs of open-loop low-pressure cycles by 44.7%, 48.8% and 48.4%. In the air conditioning of plateau trains, open-loop high-pressure cycles have slightly lower COPs, but they can supply air with elevated pressure and oxygen concentration.

Design and optimization strategy for ejectors applied in refrigeration cycles

Implementation of an ejector for expansion work recovery in transcritical Carbon Dioxide (CO2) cycles provides an opportunity to improve the efficiency of these environmentally-friendly refrigeration systems. However, literature outlining an approach to ejector design for a given application is lacking. This paper presents a tool to design a complete ejector applied in a vapor compression cycle. In this work, the developed design tool was validated using experimentally-derived polynomials at air conditioning conditions, then efficiencies were input to broaden the analysis to study a transcritical CO2 system with an ejector operating in the evaporating temperature range of −15 °C to 20 °C and gas cooler pressure in the range of 80–110 bar. The design tool allows for the calculation of the motive and suction nozzle throat diameters, the mixing section diameter, and the diffuser outlet diameter, as well as the lengths of each section, to output a full internal geometry of the ejector based on performance requirements. Individual component sub-models are presented within the proposed model structure. The model which forms the basis of the design tool was experimentally validated with a mean absolute error (MAE) between 3% and 4%. Additionally, the sensitivity of the ejector geometry and performance to component efficiencies, operating conditions, and component versus system optimization was investigated. The optimization and parametric studies conducted provided novel insights into the impact of desired efficiency and operating conditions on ejector geometry, thus allowing a designer to make decisions based on the tradeoff between ejector size and performance. For example, as the diffuser length increased by 5.1 mm to obtain an efficiency increase, to obtain a further efficiency increase of the same amount would require a 17.1 mm length increase in diffuser length. Potential model improvements and other future work are also discussed.

A review on current status of capacity control techniques for two-phase ejectors

Abstract The adoption of highly efficient vapour-compression heating, ventilation, air conditioning and refrigeration (HVAC&R) systems is compulsory to achieve a low-carbon society. Expansion work recovery using a two-phase ejector is widely recognized as one of the most promising measures to improve the energy efficiency of HVAC&R units. This holds true for all operation conditions provided that an effective capacity control technique is implemented. In this work a thorough critical review on the current status of the presently available capacity control strategies for two-phase ejectors was carried out. In addition, their pros and cons as well as the comparison of their performance were reported. It was concluded that two-phase ejectors can be properly capacity controlled in large- and medium-scale vapour-compression units. However, a suitable capacity control mechanism for small-scale vapour-compression solutions still requires a major breakthrough and is being intensively discussed among experts in the field.

Current Advances in Ejector Modeling, Experimentation and Applications for Refrigeration and Heat Pumps. Part 2: Two-Phase Ejectors

Two-phase ejectors play a major role as refrigerant expansion devices in vapor compression systems and can find potential applications in many other industrial processes. As a result, they have become a focus of attention for the last few decades from the scientific community, not only for the expansion work recovery in a wide range of refrigeration and heat pump cycles but also in industrial processes as entrainment and mixing enhancement agents. This review provides relevant findings and trends, characterizing the design, operation and performance of the two-phase ejector as a component. Effects of geometry, operating conditions and the main developments in terms of theoretical and experimental approaches, rating methods and applications are discussed in detail. Ejector expansion refrigeration cycles (EERC) as well as the related theoretical and experimental research are reported. New and other relevant cycle combinations proposed in the recent literature are organized under theoretical and experimental headings by refrigerant types and/or by chronology whenever appropriate and systematically commented. This review brings out the fact that theoretical ejector and cycle studies outnumber experimental investigations and data generation. More emerging numerical studies of two-phase ejectors are a positive step, which has to be further supported by more validation work.

Thermoeconomic optimization and comparison of the simple single-stage transcritical carbon dioxide vapor compression cycle with different subcooling methods for district heating and cooling

The transcritical carbon dioxide vapor compression cycle is commonly used for heating and cooling applications because of the high discharge temperature and large evaporation heat. Whereas, high return water temperature is usually required by the heating demands, which significantly degrades the system performances. Nowadays, various kinds of subcooling methods have been proposed for the transcritical carbon dioxide vapor compression cycle, but a systematic comparative study based on the trade-off between the thermodynamic efficiency and economic cost is needed to analyze the applicability of these methods for large-scale district heating and cooling applications. In this work, the hot water temperature increases from 323.15 K to 343.15 K for district heating, and chilled water temperature reduces from 285.15 K to 280.15 K for district cooling. The simple single-stage transcritical carbon dioxide vapor compression cycles using subcooling methods with and without expansion work recovery, including internal heat exchanger, dedicated mechanical subcooling, cooling tower and dry cooler, are respectively modeled from the energetic, exergetic and economic perspectives. Based on the dual-objective Jaya algorithm and Technique for Order of Preference by Similarity to Ideal Solution decision-making method, the parametric study is conducted with optimized system performances to analyze the effects of different ambient conditions, namely the winter mode with ambient temperature from 248.15 K to 278.15 K and the summer mode with ambient temperature from 288.15 K to 318.15 K, and the relative humidity from 30% to 90%. Afterwards, the optimal subcooling methods under different ambient temperatures are selected based on the overall optimization and comparative study. The effects of different ambient temperatures on the system performances vary with different subcooling methods without expansion work recovery, and the dry cooler is the optimal subcooling method at the ambient temperatures from 248.15 K to 268.15 K, while the cooling tower is suggested under ambient temperatures higher than 278.15 K in spite of the performance degradation with high relative humidity. Insignificant differences of system performances using different subcooling methods can be observed with expansion work recovery, and the internal heat exchanger is selected as the optimal subcooling method for winter-mode operations, while the cooling tower is also suggested as the suitable subcooling method in the summer mode.

Thermodynamic Performance Assessment of a CO2 Supermarket Refrigeration System with Auxiliary Compression Economization by using Advanced Exergy Analysis

Supermarkets are currently one of the most vital service facilities, whose number of installations is ever-growing in both developed and developing countries. On the other hand, these applications feature a copious indirect contribution to the ongoing climate change, as well as a massive use of potent greenhouse gases. In an attempt to promote climate-friendlier technologies in commercial refrigeration sector, “CO 2 only” (transcritical CO 2 or pure CO 2 ) refrigeration systems have become the mainstream of new food retails worldwide. In particular, in the last few years parallel (or auxiliary) compression has taken root in food retails as a means to enhance the energy efficiency of pure CO 2 units. The thermodynamic performance of such a promising solution can be suitably assessed with the aid of the advanced exergy analysis. The results obtained at the design outdoor temperature of 40 °C showed that the main compressor has the highest priority of enhancement, whereas the high-pressure expansion valve needs to be replaced with a device for expansion work recovery. Also, close attention had to be paid to both the gas cooler and the auxiliary compressor. The former can be improved mainly by enhancing the other components, whereas the irreversibilities related to the latter can be decreased by improving both the compressor itself and the remaining components. Finally, the implemented sensitivity analysis revealed that the improvement in the efficiency of the main compressor should be seriously considered on the part of the manufacturers.

Modeling of two-phase transcritical CO2 ejectors for on-design and off-design conditions

CO2 two-phase ejectors are used as expansion work recovery components in refrigeration or heat pump systems. A new thermodynamic model is developed for both single choking and double choking conditions to design such ejectors and investigate their performances. This model, based on the homogeneous equilibrium model (HEM), solves the conservation equations using real fluid properties rather than ideal gas assumptions. The irreversibilities due to friction in the nozzles and the diffuser are accounted for by polytropic efficiencies. The performance of a two-phase ejector is predicted for a fixed ejector geometry and given inlet operating specifications at off-design conditions. The model can also evaluate the ejector dimensions for given inlet and outlet operating conditions (on-design). The results are compared and validated against published experimental data. The effects of the irreversibilities on the ejector dimensions are investigated in detail.

An experimental investigation on exergy analysis of an ejector expansion refrigeration system

Utilisation of an ejector as an expander was experimentally investigated for an expansion work recovery in a basic refrigeration cycle. Exergy analysis was used to determine the amounts and locations of irreversibilities in the elements of the ejector expansion refrigeration system. It was seen that the ejector refrigeration cycle indicated a lower exergy destruction and a higher exergy efficiency compared to the vapour compression refrigeration cycle for each working condition. It was obtained that the values for the irreversibility of the ejector refrigeration cycle were less than in the vapour compression refrigeration cycle by 5.9-12.6% and the exergy efficiencies of ejector refrigeration cycle were 6.7-14.2% more than in the vapour compression cycle.