Ejector Refrigeration Research Articles

Thermo-economic analysis of a pumped thermal energy storage combining cooling, heating and power system coupled with photovoltaic thermal collector: Exploration of low-grade thermal energy storage

As renewable energy penetration grows, traditional power systems face significant challenges due to their intermittency and volatility. Pumped thermal energy storage (PTES) is a potential energy storage technology that has a low specific cost and geographical restriction. In this paper, a PTES system which is coupled with solar photovoltaic thermal (PVT) collectors is proposed to satisfy the demand for cooling, heating and electricity supply, and achieve energy cascade utilization. An ejector refrigeration cycle and the turbine extraction heating are accompanied with a PTES system. Thermodynamic analysis of the system is performed by evaluating the influence of key parameters on system performances for 1 MW power output. The economic analysis adopted levelized cost of energy storage (LCOS), which mainly includes investment costs, operation and maintenance costs and system depreciation. The results show that the maximum amplification of roundtrip efficiency with PVT is 12.04 % compared to the system without PVT. Moreover, the maximum average power generation benefit of PVT is 4.85 %. The increase in cold energy storage tank temperature can effectively improve the roundtrip efficiency of the system. The lower cold energy storage tank temperature and higher hot energy storage tank temperature have a negative impact on system thermal efficiency (ηthermal) but benefits for LCOS. Multi-objective optimization is carried out to obtain the optimal design performance that ηthermal and LCOS are 51.06 % and 0.533$/kWh respectively.

A full operating conditions ejector model for refrigeration systems driven by low-grade heat sources

The ejector refrigeration technology driven by low-grade heat sources constitutes as one of the crucial means to solve the energy shortage in present-day society and to reduce the global environmental pollution. Thermodynamics ejector models are the basis of performance prediction, system control and structural design in ejector refrigeration systems driven by low-grade heat sources. However, the majority of present ejector models are unable to simultaneously meet the general feasibility of full operating conditions and the level of prediction accuracy for improving the energy efficiency of the refrigeration system. In this study, a novel theoretical model of ejectors is successfully derived based on the foundation of compound-choking theory and gas dynamic relations, which easily predicts the entrainment performance under the on-design and off-design conditions in ejector refrigeration systems. Indeed, a direct solution algorithm is presented to quickly and accurately solve this model and a linear correlation is employed between the mixing loss coefficient and the back pressure at the subcritical mode. The developed model is verified with experimental results in R245fa, R134a and R600a ejector refrigeration system. The results show that the model provides a precise estimation of the entrainment performance with the mean relative errors of 2.45 %, 5.49 % and 3.67 % for R245fa, R134a and R600a refrigerants at full working conditions, while the prediction of critical condensing temperatures is considerably approximated by the experimental measurements. In the comparative analysis with the previous model, this model demonstrates a superior prediction performance, especially in the subcritical mode using the linear function mixing loss coefficient. This study will be a valuable aid in the improvement of energy efficiency in ejector refrigeration systems.

Comparative multi-objective optimization using neural networks for ejector refrigeration systems with LiBr and LiCl working agents

Education's evolution in the context of energy systems is essential for addressing sustainable energy challenges and developing a workforce equipped for future innovations, emphasizing both formal curricula and informal lifelong learning through successful energy case studies. As the global energy sector transforms to reduce carbon emissions and reliance on fossil fuels, innovations in renewable technologies like solar thermal are pivotal for promoting energy security and economic stability, supported by an educational foundation that fosters awareness and technical skills for sustainable development. Exposure to successful renewable energy systems, such as solar-powered refrigeration, offers an informal educational experience that enhances understanding and supports global educational goals, initiating with the innovative design and optimization of these systems using artificial intelligence (neural networks). Based on this formulation, the current article developed two sustainable energy systems by comparing the refrigeration cycles with two different operating fluids and various arrangements, and multi-objective optimization with an evolutionary genetic algorithm is performed for the proposed systems. The studied systems are refrigeration cycles using an ejector and without an ejector with two working fluids of lithium bromide and lithium chloride. The present work's main aim is to examine the working fluid and refrigeration system arrangements. Energy and economic modeling were performed for the proposed systems, and then parametric analysis and two-objective optimization were extracted. Parameters such as generator temperature, condenser temperature, absorber temperature, and evaporator temperature, which significantly impact the proposed system's performance, have been selected as decision parameters, and parametric analysis has been extracted for them. In addition to the mentioned parameters, diffusion mixing efficiency, nozzle efficiency, and heat exchanger have also been studied in the ejector asset system. To find the best values of decision variables, multi-objective optimization for both arrangements is conducted, and results are presented. The results have indicated that the refrigeration system using lithium chloride working fluid without an ejector achieves a coefficient of performance of 0.766 and a cost of 0.922 $/h at the optimal point, while the system with an ejector yields a higher coefficient of performance (1.047) and a slightly lower cost rate (0.991 $/h). The outcomes of this work can play a critical role for higher education institutions in advancing innovative solutions to pressing energy challenges. Lifelong learning, at the heart of educational innovation, can benefit from the integration of sustainable energy systems as a core component of informal education through the optimization of ejector refrigeration systems.

Recent advances and future outlook on solar-powered ejector refrigeration and associated multi-generation systems

Recent advances and future outlook on solar-powered ejector refrigeration and associated multi-generation systems

Triple-objective optimization using ANN+NSGA-II for an innovative biomass gasification-heat recovery process, producing electricity, coolant, and liquefied hydrogen

A novel thermal integration approach is introduced for a biomass-driven gas turbine power plant that generates electricity, coolant, and liquefied hydrogen. The designed scheme encompassed an organic flash cycle, a bi-evaporator ejector refrigeration unit, a high-temperature water electrolyzer for hydrogen production, a multi-effect desalination cycle for supplying water for electrolysis process, and a Claude cycle for hydrogen gas liquefaction. The designed system's importance comes back to using biomass feedstock as the input fuel and utilizing the hydrogen liquefaction method. In addition to the possibility of deploying the system in remote areas, it provides the opportunity for hydrogen storage in a smaller volume for more accessible storage and transportation. On the other hand, using a comparative method for selecting an environmentally friendly fluid for the heat recovery subsystem is another crucial aspect of the present study from the environmental aspect. It is found that R161 is the appropriate choice among the seven studied working fluids. Subsequently, a comprehensive evaluation of the entire system's thermodynamic and environmental aspects is performed using an intelligent process. By considering energy and exergy efficiencies along with CO2 emissions as the objective functions, a thorough sensitivity analysis and a triple-objective optimization are carried out. Hence, artificial neural networks for the objectives are developed and integrated into the NSGA-II optimization method. Employing LINMAP decision-making, the values of objective are attained, exhibiting 39.6 % for energy efficiency, 36.1 % for exergy efficiency, and 631.7 kg/MWh for CO2 emissions. Considering the optimum solution, the proposed system is capable of producing electricity, cooling, and liquefied hydrogen with capacities of 4526 kW, 1875 kW, and 21.22 m3/day, respectively. Additionally, the scenario yields an exergoenvironmental index of 0.579 and an exergetic stability index of 0.61. and a liquefied hydrogen generation rate of 21.22 m3/day.

Thermodynamic modeling and performance optimization of transcritical CO2 dual-evaporator refrigeration system enhanced with ejectors

The utilization of ejectors in transcritical CO2 refrigeration systems is known to enhance system performance significantly. However, the operational conditions play a crucial role in determining the system’s overall efficiency. This study introduces a thermodynamic model for transcritical CO2 ejector refrigeration systems and investigates the influence of operating conditions on system performance for four different refrigeration systems, and the optimization of the Nakagawa sound velocity model coefficient in the ejector modeling is carried out to enhance the accuracy of the model. Meanwhile, these research contents are also the innovation of the research. Key conclusions include: (1) Increasing the Nakagawa coefficient to 1.1 improves model accuracy. (2) Ejector inclusion enhances system COP, with one configuration showing a 43.36 % increase and another a 53.23 % increase, recommending different system setups for large spaces like supermarkets and smaller areas like refrigerated vehicles. (3) Higher evaporating pressures result in better COP for ejector systems, with a suggested maximum air cooler pressure of 9 MPa. COP also benefits from increased ejector outlet pressures. (4) AR (area ratio) of the ejector affects mass flow rates and cooling capacity significantly, while its impact on COP is minimal. Adjusting the primary throat area can control cooling capacity for varied needs. The study provides actionable insights for improving the design and efficiency of transcritical CO2 ejector refrigeration systems.

Multi-objective optimization and 3E analysis for solar-driven dual ejector refrigeration and phase change material as thermal energy storage

Ejector refrigeration cycles have garnered attention due to their inherent advantages, including simplicity, the ability to leverage low-temperature energy sources, and reduced reliance on high electrical power requirements. Optimizing these systems becomes pivotal, given the inherent challenges of low efficiency in ejector refrigeration cycles. This study explores an ejector refrigeration cycle incorporating a secondary ejector to recover expansion energy from the condenser. Solar collectors provide the necessary heat for the cycle, utilizing phase change materials for thermal storage. Initially, the impact of five key parameters, generator temperature, condenser temperature, evaporator temperature, collector area, and storage tank volume, on the cycle's performance is thoroughly investigated. Subsequently, a three-objective optimization is executed, resulting in optimal values for the mentioned parameters: 83.4 °C for the generator temperature, 35.8 °C for the condenser temperature, 6.8 °C for the evaporator temperature, 82 m2 for the collector area, and 4 m3 for the storage tank volume. The analysis of energy, exergy and exergeoeconomics for the optimal point showed that the exergy efficiency for the ejector and solar cycle is 6.78 % and 10.74 %, respectively. Also, the COP of the refrigeration cycle was obtained as 0.1858. The results showed that the solar fraction is equal to 65.4 %, and the highest amount of exergy destruction is related to solar collectors, which is equal to 8.136 kW.

Thermodynamic performance analysis and environmental impact assessment of cascade refrigeration cycles using eco-friendly nano-refrigerants

There is a lack of research in the literature on the application of nanoparticles to different cascade cycle configurations with environmental refrigerants in ultra-low temperature refrigeration applications. This study is the first on the use of nano-refrigerants in cascade refrigeration cycles. In this study, the effect of 2 wt.% of CuO to RE170 and R170-pure refrigerant utilization in cascade vapor compression refrigeration cycle (CVCRC), cascade ejector refrigeration cycle (CERC) and cascade ejector intercooler refrigeration cycle (CEIRC) are investigated to achieve higher performance values in ultra-low temperature applications. For CVCRC, CERC and CEIRC, the increases in terms of coefficient of performance (COP) with the use of nano-refrigerant were found to be 12.77 %, 8.20 %, and 6.37 %, respectively, and 18.55 %, 14.05 %, and 6.07 %, for exergy efficiency. Upon scrutinizing the results with nano-refrigerant in relation to the COP, the analysis revealed that the CEIRC cycle exhibited an improvement ranging from 13.43 % to 20.49 % in comparison to CERC. Additionally, with nano-refrigerant, the CEIRC cycle demonstrated an increase ranging from 42.39 % to 75.41 % when compared to CVCRC in COP. It was observed that the utilization of CEIRC led to a 13.03 % decrease in kg CO2 emissions in compared to CERC and a reduction of 32.53 % compared to CVCRC with using nano-refrigerant.

Compound-choking theory and artificial neural networks-based hybrid modeling for supersonic ejectors

As the core component of ejector refrigeration systems, the research of ejector mechanisms has always been a hot topic. Based on the compound-choking theory, this paper studies the relationship between the entrainment ratio and critical back pressure and designs a neural network-based online error compensation mechanism for supersonic ejectors. Firstly, a thermodynamic model of the ejector is developed by combining the ideal gas model, the compound-choking theory, and the constant-pressure mixing theory. Then, the thermodynamic relationship between the entrainment ratio and critical back pressure is derived by introducing the idea of a hypothetical mixing cross section. Compared with the existing results, our method is able to improve critical back pressure prediction accuracy by virtue of the actual entrainment ratio. Therefore, a new adaptive error compensation algorithm is proposed for supersonic ejectors based on neural networks. Thus, the proposed scheme can be regarded as a hybrid modeling method for supersonic ejectors, which combines thermodynamic laws and data-driven artificial intelligence algorithms. Experimental data from ejector refrigeration systems with R141b, R245fa, water vapor and R134a are used in this paper to verify the validity of the model. The simulation results show that our method can effectively predict the critical back pressure, and all the prediction errors are less than 10%.

Effect of generator temperature on steam ejector performance in renewable refrigeration cycle considering wet steam model and dry steam model

The rise in global warming has led to an increased utilization of cooling systems. High energy consumption associated with common refrigeration cycles not only contributes to air pollution but also intensifies the consumption of fossil fuels. Consequently, the imperative to conserve energy has become paramount in today's world. One of the methods to decrease energy consumption involves employing systems capable of harnessing waste heat from industries, solar energy, and other sources. The ejector refrigeration cycle (ERC) stands as an example of such systems. In present study, the impact of elevating the generator temperature on various aspects such as flow behavior in the ejector, aerodynamic shocks, entrainment ratio (ER), and entropy production was examined. The investigation encompassed both wet steam model (WSM) and dry steam model (DSM). Based on the findings, it was observed that with an increase in generator temperature, the ER decreases while the production entropy increases. In the WSM, the liquid mass fraction (LMF) also experiences an increase. Additionally, the Mach number distribution in the DSM surpasses that of the WSM and the temperature drop in the DSM is greater compared to the WSM. With the rise in generator temperature from 388 K to 418 K, both the DSM and WSM exhibit a decrease in ER by 52.9% and 58.7%, respectively. Furthermore, the production entropy experiences a substantial increase of 180% and 206% for the DSM and WSM, respectively.

Investigation of a novel scheme utilizing solar and geothermal energies, generating power and ammonia: Exergoeconomic and exergoenvironmental analyses and cuckoo search optimization

The integration of solar and geothermal energy sources presents a promising avenue for enhancing the efficiency and output of energy systems. This research introduces a novel hybrid system combining solar and geothermal energy for the co-generation of power, cooling, and ammonia. The proposed system integrates several cycles and technologies, including an organic Rankine cycle, an ejector refrigeration cycle, an organic flash cycle, a proton exchange membrane electrolyzer, and an ammonia synthesis reactor. Through a comprehensive 4E (energy, exergy, economic, and environmental) analysis, utilizing thermodynamic, exergoeconomic, and exergoenvironmental methodologies, this study evaluates the system's performance. The findings reveal that solar collectors are the primary contributors to system irreversibility, accounting for 78 % of the total. Notably, an increase in the condenser outlet temperature significantly decreases the cooling load, whereas elevating the turbine 1 exit pressure enhances overall power production. At optimal operating conditions, the system generates a net power of 104 kW, provides 26.07 kW of cooling capacity, and produces 3.55 kg/h of ammonia. This performance translates into a product cost of 1.193 USD/h and an exergoenvironmental impact rate of 25.31 mPts/h, alongside achieving an exergy efficiency of 9.34 %. Financially, the system promises a payback period of 2.34 years and a net present value of 1.259 million USD, highlighting its economic viability and environmental benefits.

Numerical investigation in effects of refrigerants’ thermodynamic properties on performance of supersonic ejector

ABSTRACT Using zeotropic mixtures with unique temperature glide characteristics as the working medium in heat-driven ejector refrigeration system will potentially reduce the irreversible losses in heat exchange process. However, the intrinsic link between the pure/mixture refrigerants’ thermophysical properties and the entrainment performance of supersonic ejector has not yet been elucidated. In this study, a novel ejector CFD model is established by coupling the real-gas thermodynamic equation and species transport equation, then the relationships between thermophysical properties of pure/mixture refrigerants and ejector’s dimensionless operational parameters were thoroughly investigated. The results indicated that the ejector expansion ratio rises as primary flow inlet temperature or refrigerant’s normal boiling point increases, while the dimensionless parameters of primary nozzle are relatively insensitive to the variation of primary flow inlet temperature and refrigerant’s boiling point, resulted in changes of supersonic jet expansion behaviour. Moreover, the specific volume and adiabatic index change characteristics resulted in minor fluctuations of primary nozzle’s dimensionless parameters. When the bubble point temperature is fixed at 30℃ in the condenser, the saturated vapor/liquid phase pressure glide characteristics of R600a/R1234ze mixture may lead to an increasement of ejector’s compression ratio.

Optimization and performance improvement of ultra-low temperature cascade refrigeration system based on the isentropic efficiency curve of single-screw compressor

In this paper, a cascade refrigeration system equipped with a single-screw compressor (SSC-CRS) is proposed and built in order to achieve the goal of high load cooling capacity under ultra-low temperature conditions. Firstly, the isentropic efficiency curve of the single-screw compressor (SSC) is fitted through experimental method in response to the characteristics of low suction temperature and large pressure ratio of the compressor. In addition, the analysis of SSC-CRS with 28 refrigerant pairs are made to compare the coefficient of refrigeration (COP) and power consumption. On the basis of the cascade system, the paper compares the improvement of performance between two circuits with SSC: vapor injection cascade refrigeration system (SSC-ICRS) and ejector vapor injection cascade refrigeration system (SSC-EICRS). The results indicate the COP improvement rate of SSC-ICRS system is 17.39 %–41.98 % and the COP improvement rate of SSC-EICRS system is 49.46 %–68.37 % compared with SSC-CRS.

Design and Manufacture of a Micro-Ejector and the Testing Stand for Investigation of Micro-Ejector Refrigeration Systems.

This paper describes the procedure of design and manufacture of a micro-ejector proposed for miniature ejection refrigeration systems. It describes the procedure of design, fabrication, and experimentation on supersonic micro-ejectors and makes the case for isobutane as a working fluid for such systems. It was demonstrated that it is possible to design and fabricate a micro-ejector with a cooling capacity of approximately 3 W. The discussed micro-ejector was driven by a heat source with temperature below 60 °C. The evaporation temperature was approximately 15 °C. For these operating parameters, the reported entrainment ratio was approximately 0.20. The difficulties in fabricating the micro-ejector due to its small dimensions are discussed in the paper. Additionally, the potential difficulties and solutions related to ensuring and maintaining stable operation of the testing stand are presented. The performance of the proposed system is demonstrated and discussed, including relations between mass entrainment ratio, compression ratio, cooling capacity, and temperature.

Comparative evaluation of experimental ejector refrigeration system for different operating configurations

In this study, a comparative performance evaluation of an experimental ejector refrigeration system was conducted for various operating modes. The experimental setup was operated in different modes: conventional vapour compression refrigeration (CVCR), conventional dual-evaporator system (CDES), and dual-evaporator ejector system (DEES). The system was tested under different operating conditions, including varying condenser temperatures and mass flow rates. The results of the evaluation showed that the highest total cooling capacity and coefficient of performance (COP) were achieved in the DEES mode, while the lowest total cooling capacity was observed in the CDES mode. The lowest compressor power was calculated when the system was operated in DEES mode. When the condenser temperature was 33°C, the compressor power obtained in the DEES was 22.7%, 5.4%, and 17.7% lower than that of the CVCRA, CVCRB, and CDES modes, respectively. In conclusion, the performance of the ejector-operated system was found to be superior to the other configurations, and the ejector contributed positively to the system performance.

Performance analysis and multi-objective optimization of the offshore renewable energy powered integrated energy supply system

Offshore renewable energy technologies offer a promising prospect for energy supply on offshore islands. However, traditional wind and solar energy sources exhibit strong variability and cannot fully meet the energy demands of users. At the same time, the energy demand of users also has great volatility, so the supply side and demand side of energy cannot match well. Existing renewable energy systems often utilize thermal power generation as a stabilizer for the system, however, this approach is difficult to apply in offshore conditions. This study introduces an innovative multi-energy complementary system that integrates seawater freezing desalination, refrigeration and power-hydrogen-ammonia co-generation, driven by ocean thermal energy, wind energy, and solar energy. The system incorporates the use of a new developed small temperature difference ejector refrigeration cycle to stabilize the entire system and produce low-temperature refrigeration. By utilizing the seawater freezing desalination process to minimize energy conversion losses and balancing fluctuations in multiple energy inputs and user demands through ammonia-hydrogen co-production, this approach effectively minimizes energy waste, enhances energy utilization efficiency, and reduces excess power handling. The purpose is to optimize the configuration of the energy conversion subsystem within the multi-energy complementary multi-effect co-generation system, thus improving the economic feasibility and reliability of the system in providing energy and freshwater supply, ultimately achieving the goals of reducing energy waste, achieving high conversion efficiency, and minimizing equipment investment. This study conducts an economic analysis and optimization of a multi-energy complementary system, utilizing a 2 MW-level OTEC subsystem as a stabilizer. Both equipment investment and operating costs are considered in the economy analysis. The carbon emission reduction performance of this system is evaluated. The performance optimization results show that the system achieves an energy storage efficiency of 65.96 %, and the curtailment rate of this system is only 3.99 %, significantly lower than the 10 % curtailment rate in traditional system. The proposed system can meet the annual electricity demand of 33.09 million kWh, as well as a cooling demand of 546.81 million kWh. Under typical conditions, the ocean thermal energy conversion cycle exhibits a power efficiency of 0.85 % and a refrigeration efficiency of 29.10 %. Meanwhile, it annually reduces CO2 emissions by 2.54 million tons, demonstrating significant environmental benefits. This proposed system is mainly applicable to tropical waters with high surface water temperatures and depths of no less than 600 m worldwide. This study offers a practical and economically beneficial solution for energy and freshwater supply on offshore islands.

4E analysis and triple objective NSGA-II optimization of a novel solar-driven combined ejector-enhanced power and two-stage cooling (EORC-TCRC) system

This study proposed an innovative combined ejector-enhanced organic Rankine cycle and two-stage compression refrigeration cycle (EORC-TCRC), to investigate its potential to revolutionize energy utilization and offer a sustainable solution for the current energy challenge. Energy, exergy, economic, and environmental (4E) analysis of the novel EORC-TCRC system was conducted first. The performance appraisal of the novel system compared to the conventional combined power and ejector refrigeration system has been evaluated. The evolutionary non-dominated Sort Genetic (NSGA-II) optimization algorithm was implemented to ascertain triple-objective optimal system operating conditions. The results revealed a significant improvement in refrigeration output, energy, and exergy efficiency with values of 220.06 kW, 11.67%, and 17.07%, respectively, compared to the conventional Rankine power and ejector refrigeration system. By different selections of the objective functions, four groups comprised of Multi-Objective CT–ղex, Multi-Objective CT–ղTh, Multi-Objective ղex–ղTh, and Triple-Objective mode presented to sought NSGA-II optimization results. The optimization results of Multi-Objective CT–ղTh mode indicated that the best thermal efficiency and overall system cost rate operating conditions are 28.25% and 78,820 ($/year), respectively. While the optimal system operating condition occurs in the Triple-Objective ղex- ղTh-CT with the exergetic efficiency of 41.69%.

Thermodynamic assessment of a novel solar powered trigeneration system for combined power generation, heating, and cooling

Solar power tower (SPT) technology is the mature technology among the various concentrated solar technologies for energy generation. Therefore, it is necessary to develop the efficient energy generation system that utilizes the SPT plant. In the current study, a novel trigeneration system was presented to utilize the SPT for combined power generation, heating, and cooling. The trigeneration system consists a helium Brayton cycle and organic Rankine cycle (ORC) with ejector refrigeration system for recovering the waste heat. The power was produced by the helium Brayton cycle and ORC turbine whereas, cooling and heating was produced simultaneously by the condenser and evaporator respectively. For building applications such as hospitals and hostels, the heating and cooling effects were generated at 50°C and 10°C respectively. Finally, the optimal system exhibits exergy and energy efficiency of 25.12% and 23.3%, respectively, when all the studied parameters are taken into consideration. Apart from this power output, heating and cooling productions were observed as 14,998, 60.52 and 8.25 kW and respectively at the 2.3 of compressor pressure ratio, 197.2°C of inlet temperature of ORC turbine.

Dynamic analysis and control strategy of ORC coupled ejector expansion refrigeration cycle driven by geothermal water

Organic Rankine cycle combined ejector expansion refrigeration cycle (ORC-EERC) has significant potential for utilizing low-temperature heat. The study on dynamic response of the ORC-EERC combined system plays a particularly important role in optimizing the control strategy for the system, given the instability of the low-temperature heat source. In this paper, the ORC-EERC dynamic models with single and dual condensers are proposed. The simulation results show that the proposed improved model of EERC subsystem presents more accurate results relevant to the experiment system. The impact of the ORC subsystem on the refrigeration subsystem is more pronounced in the ORC-EERC system with a single condenser than in the system with dual condensers. In addition, the phenomenon of chocking in the ejector throat leads to the degradation of system performance when the heat source is disturbed. Therefore, a multi-device cooperative control strategy is proposed to enhance the safety and performance of the system. In the case study of geothermal water mass flow scheduling disturbance, the control strategy increases the cooling capacity of the system by a maximum of 9.29%.

Techno-economic assessment of solar-driven ejector refrigeration system assisted with daytime radiative condenser

Solar-driven ejector refrigeration is an emerging technology, but not sustainable due to huge heat rejection to the environment, leading to the heat island effect. However, this can be made sustainable by utilizing a daytime radiative condenser, but not yet been explored. Hence, a novel solar-driven ejector refrigeration system assisted with a daytime radiative condenser is investigated based on energy, exergy and economic perspectives. This system is powered by a parabolic trough collector along with thermal energy storage and double two-phase ejectors. The system performance is optimized by employing the genetic algorithm. The impact of several operating scenarios and seasonal climatic conditions is explored for different refrigerants. The best optimum coefficient of performance and exergy efficiency are obtained with the R123, but the total cost and radiative condenser area are lowest with the R1234ze(E). The performance is higher with lower ambient and radiative condenser temperatures but with higher solar irradiation for all three refrigerants. The performance is maximum during December for Jaisalmer and January for Varanasi and Kolkata, while lowest in May for Jaisalmer and June for Varanasi and Kolkata. The specific total cost and radiative condenser area are maximum from July to August for all considered locations. This study reveals the proposed system as a promising option, but the large space requirement may be the main hurdle behind the practical implementation.