F. Vidan-Falomir, R. Larrondo-Sancho, D. Sánchez, R. Cabello
{"title":"Evaluation of different subcooling arrangements in a CO2 refrigeration plant using extractions from the flash-gas tank","authors":"F. Vidan-Falomir, R. Larrondo-Sancho, D. Sánchez, R. Cabello","doi":"10.1016/j.ijrefrig.2025.03.037","DOIUrl":"10.1016/j.ijrefrig.2025.03.037","url":null,"abstract":"<div><div>Carbon dioxide (CO<sub>2</sub>) is a widely used natural refrigerant with a low critical temperature (∼31 °C), that makes necessary the use of complex cycle arrangements to enhance the performance of refrigerating plants, especially at high ambient temperatures. Considering this, the present work evaluates two simple subcooling arrangements experimentally based on stream extractions from the flash-gas tank installed between the back-pressure valve and the thermostatic expansion valve. These extractions are expanded in a subcooler installed at the exit of the gas-cooler, providing the subcooling effect depending on the tank pressure and the fluid extracted (liquid or vapour). Since the flash-gas tank pressure introduces a new degree of freedom, an optimisation process for maximising the COP is mandatory depending on the heat-rejection conditions (temperature and pressure). Therefore, this work presents the optimisation process for three heat-rejection temperatures (28, 31 and 34 °C) using extractions from vapour or liquid, reaching COP improvements up to 9.4 % with optimal pressure reductions of up to 3.0 bar.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"175 ","pages":"Pages 334-344"},"PeriodicalIF":3.5,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143851967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xilong Shi , Chenghu Zhang , Yan Liu , Fazhong Wang
{"title":"Investigation on multi-stage compression high-temperature heat pump system based on R718 and other low GWP refrigerants","authors":"Xilong Shi , Chenghu Zhang , Yan Liu , Fazhong Wang","doi":"10.1016/j.ijrefrig.2025.04.019","DOIUrl":"10.1016/j.ijrefrig.2025.04.019","url":null,"abstract":"<div><div>Under the dual-carbon strategy, electrifying industrial heating is a key trend. This study develops three types of thermodynamic cycle models for compression high-temperature heat pump (HTHP) systems. The effects of evaporation temperature on the compression characteristics of R718, R245fa, R1234ze(Z), and R1336mzz(Z) are investigated, along with an analysis of the available energy variation within the system. Results show that R718 exhibits superior thermodynamic properties compared to other refrigerants at high evaporation temperatures, with its coefficient of performance (COP) increasing from 4.70 to 5.34. However, the high pressure ratio and excessive superheat (up to 150 °C at 90 °C evaporation temperature) limits its practical application. When the lifting temperature is set at 40 °C, the three-stage compression (THC) system achieves an optimal performance value of 5.47, with a pressure ratio of 1.58 and exhaust superheat of 35.38 °C. The exergy efficiency of the three-stage compression (TWC) and THC systems using R718 is 39.6 % and 56.1 % higher than that of the single-stage compression (SC) system at a waste heat source temperature of 95 °C, respectively. These findings emphasize that multi-stage compression significantly enhances energy efficiency. Furthermore, this study provides valuable guidance for practical engineering applications.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"176 ","pages":"Pages 238-253"},"PeriodicalIF":3.5,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143937042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qiang Cao , Pengcheng Wang , Zhiping Wang , Yuji Chen , Lichun Ge , Peng Li , Qinyu Zhao , Bo Wang , Zhihua Gan
{"title":"Study on expansion methods of the DC flow for transferring the temperature-distributed refrigeration power","authors":"Qiang Cao , Pengcheng Wang , Zhiping Wang , Yuji Chen , Lichun Ge , Peng Li , Qinyu Zhao , Bo Wang , Zhihua Gan","doi":"10.1016/j.ijrefrig.2025.04.017","DOIUrl":"10.1016/j.ijrefrig.2025.04.017","url":null,"abstract":"<div><div>The temperature-distributed refrigeration power in the regenerator is effectively transferred by extracting the inner direct-current (DC) flow from the regenerator. The transfer efficiency is improved by up to 1–2 times compared with traditional transfer methods because there is no radial thermal resistance in the regenerator during the transfer process. However, the specific heat capacity between the DC flow and the gas to be liquefied is usually mismatched due to the difference in pressure or working fluid, resulting in heat exchange loss. In this paper, we propose the expansion methods of the DC flow. The refrigeration power at the cold end of the refrigerator is increased by the expansion methods due to the liquefaction of the DC flow. Meanwhile, the distribution of specific heat capacity in the DC flow is altered, which generally enhances its availability. For the case study of <sup>4</sup>He, the availability of the expanded DC flow is improved by around 40 % after expansion. The specific heat capacity between the DC flow and the gas to be liquefied becomes better matched, and the theoretical helium liquefaction rate is improved by approximately 25 %. In addition, the figure of merit (FOM) for liquefaction is enhanced by about 20 %, which includes the compression work of the expanded DC flow returning to the original refrigerator, form a closed cycle. This research enriches the study of the temperature-distributed regenerative refrigeration method and provides a reference for improving the transfer efficiency of the temperature-distributed refrigeration power and the liquefaction rate of cryogenic gases.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"176 ","pages":"Pages 94-105"},"PeriodicalIF":3.5,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143916755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Performance comparison investigation on different pulse tube position heat pumps with power recovery displacer","authors":"Shenglin Zhu , Xi Chen , Yifan Zhu , Yingxia Qi","doi":"10.1016/j.ijrefrig.2025.04.014","DOIUrl":"10.1016/j.ijrefrig.2025.04.014","url":null,"abstract":"<div><div>Spacecraft waste heat is dissipated into space primarily by radiation. To improve the heat dissipation efficiency of spacecraft radiators in high-temperature environments and reduce heat wastage in spaceflight thermal control systems, thermoacoustic heat pumps (TAHP) are considered a viable method for increasing radiator cooling temperatures and recovering waste heat. In this study, one-dimensional simulations are used to optimize the geometrical parameters of the 100-watt work recovery thermoacoustic heat pump (WRTAHP) for various pulse tube positions. The performances of the two systems are compared at a cold-end temperature of 293 K and a hot-end temperature of 353 K. The results reveal that a heating capacity of 256 W with a relative Carnot efficiency of 35.01 % is achieved for the pulse tube front-type thermoacoustic heat pump (FTTAHP), whereas the pulse tube back-type thermoacoustic heat pump (BTTAHP) obtains a heating capacity of 225 W with a relative Carnot efficiency of 30.59 %. As the cold-end temperature decreases, the coefficient of performance is reduced for FTTAHP, while the performance of BTTAHP shows a substantial improvement. At a cold end temperature of 233 K and a hot-cold end temperature difference of 60 K, a heating capacity of 268 W with a relative Carnot efficiency of 50.57 % is achieved for BTTAHP. Furthermore, the heating capacity of the BTTAHP is not significantly increased by adopting the active phase adjustment structure. In summary, the FTTAHP is suitable for spacecraft radiator applications and avoids high temperatures affecting compressor operation, whereas the BTTAHP is better suited for low-temperature heating.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"176 ","pages":"Pages 1-16"},"PeriodicalIF":3.5,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143891291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiesong Jian , Yingchao Zhang , Guohua Wang , Wei Wang
{"title":"Optimizing refrigerant charge in PHEV air conditioning system through genetic algorithm, COP, exergy analysis and condenser size adjustment","authors":"Jiesong Jian , Yingchao Zhang , Guohua Wang , Wei Wang","doi":"10.1016/j.ijrefrig.2025.04.015","DOIUrl":"10.1016/j.ijrefrig.2025.04.015","url":null,"abstract":"<div><div>The air - conditioning of Plug-in Hybrid Electric Vehicle (PHEV) cools the cabin and battery. Refrigerant charge greatly affects the system’s COP. This paper explores battery heat dissipation’s impact on optimal refrigerant charge, which is corresponding to the maximum system COP, using genetic algorithm, COP, exergy analysis, and condenser size enlargement. Firstly, under each steady-state condition, the optimal refrigerant charge is estimated using the genetic algorithm, with the maximum COP as the response. The findings prove that the optimal refrigerant charge rises with the battery thermal load. Then, based on the exergy analysis results, increasing the condenser size leads to a significant improvement in the system COP, with a maximum increase of 35.3 %. Meanwhile, the optimal refrigerant charge rises in accordance with the increase in battery heat load, and these optimal refrigerant charges are all bigger than the original system values. Finally, after the condenser size is increased, steady-state tests with different battery heat dissipations show that a refrigerant charge of 685 g (optimal when battery heat dissipation is 0 W), leads to a COP decrease of up to 13.3 %. While, with a refrigerant charge of 1200 g (optimal at battery heat dissipation 4350 W), the COP decline relative to its peak value is just 1.9 %. The analysis indicates that, when determining the refrigerant charge, the battery thermal load should be relatively high to reduce the impact of the refrigerant charge on the system’s performance.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"176 ","pages":"Pages 177-191"},"PeriodicalIF":3.5,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143929056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alain Le-Bail, Nasser Hamdami, Cyril Toublanc, Michel Havet
{"title":"An overview of selected “subzero” temperature storage regimes of foods: regulations and perspectives about the expected impact of the \"three degrees of change\" initiative on the shelf life of frozen foods","authors":"Alain Le-Bail, Nasser Hamdami, Cyril Toublanc, Michel Havet","doi":"10.1016/j.ijrefrig.2025.04.009","DOIUrl":"10.1016/j.ijrefrig.2025.04.009","url":null,"abstract":"<div><div>Frozen storage temperature plays a crucial role in preserving the initial quality of frozen foods. The most used storage temperature of frozen food is -18°C and is based on 0°F, which corresponds to -17.8°C. This temperature does not correlate with a specific ratio of frozen water in foods (“level of frozenness\"-LOF) and has been arbitrarily chosen. The fact is that at -18°C, most foods never reach a 100 % LOF (usually in the range of 95 % LOF). The 100 % LOF refers to a state in which the maximum ice crystallization zone has been covered (usually around -30°C). New low-temperature storage modes, such as chilling, superchilling, and supercooling, gained attention in academia and in the food industry, pushing the boundaries of existing regulations. The recent \"Three Degrees if Change\" initiative launched by the University of Birmingham (UK) aims at exploring the interest and impact of changing the frozen food storage temperature from -18°C to -15°C. This paper proposes a review of the current regulations in connection with selected subzero temperature storages. Based on the principle of the Q<sub>10</sub> models, a Q3 model is proposed showing that frozen foods stored at -15°C may lose around 30 % of their quality life from the sensorial point of view. Raising the temperature to -15°C should not pose a major microbial risk; however, this point must be under scrutiny. In particular, the permitted temperature oscillations during transport and at the retail outlet may require some adjustment.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"176 ","pages":"Pages 336-344"},"PeriodicalIF":3.5,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143949029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Numerical simulation of two-phase refrigerant separation in conical cyclones for vapor-compression refrigeration systems","authors":"Faramarz Ilamidoshmanziari, Long Ni","doi":"10.1016/j.ijrefrig.2025.03.040","DOIUrl":"10.1016/j.ijrefrig.2025.03.040","url":null,"abstract":"<div><div>The study emphasizes the need for vapor-liquid separators in refrigeration systems to increase efficiency and reliability. A separator utilized ahead of the evaporator serves several purposes: by removing vapor from the mixture, it improves evaporator compactness via increasing heat exchange efficiency, lowers evaporator pressure drop, and reduces compressor work. This work gives a comprehensive computational fluid dynamics (CFD) investigation of vapor-liquid separation processes for the refrigerant R32 using five conical cyclone separator models. The study focuses on evaluating flow patterns and configurations within the separator, and its geometric properties, while changing the inlet mass flow rate and quality from 0.012 kg.s<sup>-1</sup> to 0.036 kg.s<sup>-1</sup> and 0.1 to 0.3, respectively. The results reveal that all the geometric models have a liquid separation efficiency above 99 %. In addition, it has been shown that decreasing the conic diameter can improve vapor separation by as much as 25 %. Variations in the height of the cylindrical section have little effect on the vapor separation efficiency. Also, the vapor separation efficiency increases at higher refrigerant flow rates, as indicated by the study results. Relevant to the above context, this investigation yields important knowledge on the design and optimization of refrigeration systems, especially from the perspective of the vapor-liquid separation processes.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"175 ","pages":"Pages 219-234"},"PeriodicalIF":3.5,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143845047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Experimental and numerical investigation of a high-effectiveness cryogenic PCHE for space 80 K Brayton cryocooler","authors":"Zixin Zhang , Liang Chen , Hongyu Lv , Sichen Li , Yu Hou","doi":"10.1016/j.ijrefrig.2025.04.013","DOIUrl":"10.1016/j.ijrefrig.2025.04.013","url":null,"abstract":"<div><div>Growing space cooling demand has made reverse Brayton cryocooler a promising technology, requiring higher effectiveness and lighter weight recuperative heat exchangers. This study proposes a novel cryogenic printed circuit heat exchanger (PCHE) design for an 80 K space Brayton cryocooler, with both high thermal performance and compactness. Unlike conventional PCHEs, the proposed cryogenic PCHE features high-density micro-fins (114 cm<sup>-2</sup>) and a thin wall (wall thickness of 0.1 mm), achieving a compactness of 4548 m<sup>2</sup>·m<sup>-3</sup>, 82 % higher than conventional designs. A counter-flow heat transfer model is developed, incorporating axial heat conduction effects typically overlooked in PCHE design models. Through systematic optimization, the cryogenic PCHE achieves a heat duty of 2.2 kW for gas neon between 80 K and 313 K, with compact core dimensions of 460 mm × 86 mm × 82 mm. Experimental testing demonstrated the exceptional performance of the cryogenic PCHE, achieving a heat transfer effectiveness of 97.3 %, surpassing conventional PCHEs, with only a 7.6 kPa total pressure drop. Compared to conventional plate-fin heat exchangers (PFHE) used in ground Brayton cryocoolers, the cryogenic PCHE shows superior performance. This design achieves a performance evaluation criterion of 1.8, while reducing 80 % volume requirements at equivalent thermal effectiveness. Additionally, the analysis reveals a 1.2 % effectiveness deterioration due to axial conduction, which leads to an 87.4 % overestimation of the cryocooler's cooling capacity, highlighting its significance in high-effectiveness cryogenic heat exchanger design.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"176 ","pages":"Pages 26-39"},"PeriodicalIF":3.5,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Study on the effect of ejector on the performance of low temperature transcritical CO2 two-stage compression refrigeration system","authors":"Xiaocui Li , Liang Zhang , Xiaofeng Xu","doi":"10.1016/j.ijrefrig.2025.04.010","DOIUrl":"10.1016/j.ijrefrig.2025.04.010","url":null,"abstract":"<div><div>This paper presents a refrigeration experimental platform that can switch between a two-stage transcritical CO<sub>2</sub> compression system with and without an ejector. Through theoretical simulation and experimental methods, the effects of ejector on system performance were investigated under the conditions of indoor temperatures ranging from -34∼-20 °C, gas cooler pressures ranging from 8.2∼9.7 MPa, and low-pressure electronic expansion valve (EEV) openings ranging from 50 %∼100 %. The study reveals that the primary reason for the discrepancy between theoretical simulation and experimental results is that the theoretical model of compressor volumetric efficiency is insensitive to changes in low-pressure compression ratio, while the actual piston compressor is highly sensitive to such changes. The results also demonstrate that the application of ejector significantly enhances system’s refrigeration capacity and coefficient of performance (COP), as well as reduces energy consumption and carbon emissions. The variation of low-pressure EEV opening has a more significant impact on the ejector’s enhancement of refrigeration capacity and COP than indoor air temperature and gas cooler pressure. The ability of ejector to reduce system power consumption is relatively stable under different conditions. Further analysis indicates that the entrainment capability and efficiency of the ejector, as well as the volumetric and isentropic efficiencies of low-pressure compressor, are most sensitive to changes in low-pressure EEV opening. The adaptive regulation of ejector can maintain the stability of system’s refrigeration capacity per unit mass and volume. Only by adjusting low-pressure EEV opening to the optimal level can the ejector fully replace the function of high-pressure EEV.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"175 ","pages":"Pages 299-313"},"PeriodicalIF":3.5,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Experimental study of dedicated mechanical subcooling systems in flake ice machines","authors":"Xian Lyu, Zhili Sun, Wenfu Zhang, Dongxia Wu","doi":"10.1016/j.ijrefrig.2025.04.011","DOIUrl":"10.1016/j.ijrefrig.2025.04.011","url":null,"abstract":"<div><div>This paper proposes a method for enhancing the performance and production capacity of a flake ice machine by integrating a dedicated mechanical subcooling system with the existing setup. The optimal flow rate between different configurations of the ice-making system (IMS) and the dedicated mechanical subcooling system (DMS) was determined through theoretical analysis. A performance test bench was established for the flake ice machine to compare and analyze the optimal ice production when the dedicated mechanical subcooling system was activated and deactivated. The optimal ice-scraping cycle of the evaporation bucket of the flake ice machine was identified when the ice-making dry rate was 2.0. An economic analysis of the system was conducted. The results indicated that using an R404A scroll compressor for the IMS and an R134a piston compressor for the dedicated mechanical subcooling system, the optimal refrigerant flow rate of the IMS and the DMS was 3.0–4.0 and the optimal ice-scraping cycle was 26.7 s when the ice-making dry rate was 2.0. Applying the DMS resulted in a 7.4 % increase in the operational performance of the machine. And the payback period for incorporating the DMS was determined to be 0.76 years. Research demonstrates that the combination of a DMS with a flake ice machine system presents novel insights for enhancing the operational performance of the flake ice machine system and increasing its production output.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"175 ","pages":"Pages 345-357"},"PeriodicalIF":3.5,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143855380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}