Pub Date : 2025-12-31DOI: 10.1016/j.ijrefrig.2025.12.038
Shuo Feng , Hainan Zhang , Kai Liu , Tao Ding , Sujun Dong , Yongji Liu , Shuangquan Shao , Yanhui Feng
The cooling requirements of new-generation airborne devices, coupled with the demand for extended endurance of aircraft under high heat loads, impose higher performance requirements on airborne vapor compression refrigeration systems operating under large temperature differences. Auto-cascade refrigeration system shows significant advantages in this application domain. However, there is little research within the relevant temperature range, especially experimental studies. To address the need for large-temperature-difference cooling in aircraft, this paper firstly presents the experimental investigation of an auto-cascade refrigeration system for aircraft using R245fa/R134a as the refrigerant with a heat source temperature of 20 °C and heat sink temperatures ranging from 55 °C to 100 °C. The effects of refrigerant charge, mixed refrigerant concentration, heat sink temperature, and valve opening on the performance were analyzed. The results can help the design of future aircraft refrigeration systems and promote the application of auto-cascade refrigeration in higher temperature range.
{"title":"Experimental investigation on an oil-cooled auto-cascade refrigeration system for aircraft","authors":"Shuo Feng , Hainan Zhang , Kai Liu , Tao Ding , Sujun Dong , Yongji Liu , Shuangquan Shao , Yanhui Feng","doi":"10.1016/j.ijrefrig.2025.12.038","DOIUrl":"10.1016/j.ijrefrig.2025.12.038","url":null,"abstract":"<div><div>The cooling requirements of new-generation airborne devices, coupled with the demand for extended endurance of aircraft under high heat loads, impose higher performance requirements on airborne vapor compression refrigeration systems operating under large temperature differences. Auto-cascade refrigeration system shows significant advantages in this application domain. However, there is little research within the relevant temperature range, especially experimental studies. To address the need for large-temperature-difference cooling in aircraft, this paper firstly presents the experimental investigation of an auto-cascade refrigeration system for aircraft using R245fa/R134a as the refrigerant with a heat source temperature of 20 °C and heat sink temperatures ranging from 55 °C to 100 °C. The effects of refrigerant charge, mixed refrigerant concentration, heat sink temperature, and valve opening on the performance were analyzed. The results can help the design of future aircraft refrigeration systems and promote the application of auto-cascade refrigeration in higher temperature range.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"183 ","pages":"Pages 123-132"},"PeriodicalIF":3.8,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923295","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}
Pub Date : 2025-12-31DOI: 10.1016/j.ijrefrig.2025.12.036
Shengyuan Zhao , Yanxia Li , Fengjiao Yu , Jing Ren , Zhongliang Liu , Zhongyuan Wang
Frost formation is a prevalent phase transition phenomenon in both natural environments and industrial processes. Current research on frost formation mechanisms and processes has primarily focused on macroscopic scales. This macroscopic focus limits the ability to investigate thoroughly the nanoscale dynamic processes and underlying mechanisms, particularly the systematic evolution characteristics during initial frost formation under ordinary-low and cryogenic conditions. In this study, a physical model for the initial stage of frost formation on cryogenic surfaces was developed using molecular dynamics simulations, enabling nanoscale investigation of early-stage frost formation at low temperatures. The simulation results demonstrate that the frost morphology on copper surfaces varies with substrate temperature, consistent with experimental observations. By employing MATLAB for phase identification of water molecules, we found that the frost crystal structure transitions from dendritic to clustered morphology as the cold surface temperature decreases. This transition results in a non-monotonic variation in frost coverage area: it decreases first, then increases, and subsequently decreases again. Furthermore, the frost formation completion time does not vary monotonically with decreasing cold surface temperature. Within the temperature range of -90 °C to -30 °C, the completion time decreases with temperature reduction; whereas between -130 °C and -90 °C, the formation time increases with further cooling. All these variations are significantly influenced by the evolving frost morphology patterns.
{"title":"Molecular dynamics study of the initial frosting phenomenon on cold surfaces from ordinary-low to cryogenic temperatures","authors":"Shengyuan Zhao , Yanxia Li , Fengjiao Yu , Jing Ren , Zhongliang Liu , Zhongyuan Wang","doi":"10.1016/j.ijrefrig.2025.12.036","DOIUrl":"10.1016/j.ijrefrig.2025.12.036","url":null,"abstract":"<div><div>Frost formation is a prevalent phase transition phenomenon in both natural environments and industrial processes. Current research on frost formation mechanisms and processes has primarily focused on macroscopic scales. This macroscopic focus limits the ability to investigate thoroughly the nanoscale dynamic processes and underlying mechanisms, particularly the systematic evolution characteristics during initial frost formation under ordinary-low and cryogenic conditions. In this study, a physical model for the initial stage of frost formation on cryogenic surfaces was developed using molecular dynamics simulations, enabling nanoscale investigation of early-stage frost formation at low temperatures. The simulation results demonstrate that the frost morphology on copper surfaces varies with substrate temperature, consistent with experimental observations. By employing MATLAB for phase identification of water molecules, we found that the frost crystal structure transitions from dendritic to clustered morphology as the cold surface temperature decreases. This transition results in a non-monotonic variation in frost coverage area: it decreases first, then increases, and subsequently decreases again. Furthermore, the frost formation completion time does not vary monotonically with decreasing cold surface temperature. Within the temperature range of -90 °C to -30 °C, the completion time decreases with temperature reduction; whereas between -130 °C and -90 °C, the formation time increases with further cooling. All these variations are significantly influenced by the evolving frost morphology patterns.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"183 ","pages":"Pages 231-240"},"PeriodicalIF":3.8,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923223","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}
Pub Date : 2025-12-30DOI: 10.1016/j.ijrefrig.2025.12.034
Shulin Zhang , Lei Chen , Zhen Shangguan , Juan He , Jie Ma , Xiaotian Peng , Hao Peng
Fluctuations in regasification rates at liquefied natural gas (LNG) receiving terminals, driven by spatiotemporal variability of downstream demand, hinder the effective recovery of LNG cold energy. To address this issue, an integrated cold and power cogeneration system incorporating cold energy storage (CES) units is proposed. The system combines an organic Rankine cycle (ORC), two CES units, and a cold energy recovery module. This study systematically analyzes the operating characteristics of the proposed system under both steady-state and unsteady conditions. Under steady-state conditions, the influence of key operating parameters on system efficiency is investigated, and a multi-objective optimization approach is introduced to coordinate these parameters. Under unsteady conditions, the impact of regasification rate fluctuations on system performance is examined, and, based on real case studies, the instantaneous performance, single-day operation, and multi-day behavior of the system are evaluated. In addition, environmental and economic analyses are conducted. The results demonstrate that the proposed CES units significantly enhance system performance, increasing the cold energy recovery rate from 10.30% to 86.04% and improving the exergy efficiency to 44.81%. The system achieves an average equivalent power output of 616 MW·h/d and CO2 emission reductions of 282 t/d. Although the initial investment cost increases slightly, the net present value rises by 184%, the annual profit increases by 187%, and the payback period is shortened to 1.1 years. These results demonstrate that the proposed configuration provides a practical and flexible solution for enhancing LNG cold energy utilization, with strong potential for large-scale deployment across diverse terminal types.
{"title":"Thermodynamic, environmental and economic analysis of liquefied natural gas cold energy polygeneration system under fluctuating regasification rates","authors":"Shulin Zhang , Lei Chen , Zhen Shangguan , Juan He , Jie Ma , Xiaotian Peng , Hao Peng","doi":"10.1016/j.ijrefrig.2025.12.034","DOIUrl":"10.1016/j.ijrefrig.2025.12.034","url":null,"abstract":"<div><div>Fluctuations in regasification rates at liquefied natural gas (LNG) receiving terminals, driven by spatiotemporal variability of downstream demand, hinder the effective recovery of LNG cold energy. To address this issue, an integrated cold and power cogeneration system incorporating cold energy storage (CES) units is proposed. The system combines an organic Rankine cycle (ORC), two CES units, and a cold energy recovery module. This study systematically analyzes the operating characteristics of the proposed system under both steady-state and unsteady conditions. Under steady-state conditions, the influence of key operating parameters on system efficiency is investigated, and a multi-objective optimization approach is introduced to coordinate these parameters. Under unsteady conditions, the impact of regasification rate fluctuations on system performance is examined, and, based on real case studies, the instantaneous performance, single-day operation, and multi-day behavior of the system are evaluated. In addition, environmental and economic analyses are conducted. The results demonstrate that the proposed CES units significantly enhance system performance, increasing the cold energy recovery rate from 10.30% to 86.04% and improving the exergy efficiency to 44.81%. The system achieves an average equivalent power output of 616 MW·h/d and CO2 emission reductions of 282 t/d. Although the initial investment cost increases slightly, the net present value rises by 184%, the annual profit increases by 187%, and the payback period is shortened to 1.1 years. These results demonstrate that the proposed configuration provides a practical and flexible solution for enhancing LNG cold energy utilization, with strong potential for large-scale deployment across diverse terminal types.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"183 ","pages":"Pages 133-152"},"PeriodicalIF":3.8,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923296","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}
Pub Date : 2025-12-30DOI: 10.1016/j.ijrefrig.2025.12.025
Santiago Valencia-Cañola , Federico Méndez , Carlos A. Bustamante
Ejector Refrigeration Systems (ERS) can obtain their primary energy source from renewable sources such as solar radiation, which transfers heat to the ERS generator to achieve optimal operation. Direct-expansion solar collectors have been gain attention in systems such as solar heat pumps, avoiding the use of additional subsystems and energy sources and reducing costs and electricity consumption. In this study, the dynamic performance of an ERS with direct-expansion solar generator is assessed by means of a validated mathematical model that couples ERS subsystem operation. The proposed model predicts the global behavior of the cycle by describing mass, momentum and energy transport in each subsystem and by coupling their inlet and outlet conditions. An ERS basic design for average meteorological condition with direct-expansion solar generator is numerically analyzed for different transient operating conditions, in terms of solar radiation and ambient temperature, obtained from the typical meteorological year (TMY) of Mexico City. The results show that in favorable environmental conditions, the system can operate 2.3 h longer than the average day because the generator can maintain the refrigerant vapor phase for a longer period. However, refrigerant overheating increases, causing a reduction in the entrainment ratio (ER) and coefficient of performance (COP). This study shows that the ERS with a direct-expansion solar generator can operate for more than 90% of the TMY, reaching ER values of up to 0.6 and COP of up to 0.5, which are close to conventional ERS.
{"title":"Dynamic performance analysis of an ejector refrigeration system with a direct-expansion solar generator","authors":"Santiago Valencia-Cañola , Federico Méndez , Carlos A. Bustamante","doi":"10.1016/j.ijrefrig.2025.12.025","DOIUrl":"10.1016/j.ijrefrig.2025.12.025","url":null,"abstract":"<div><div>Ejector Refrigeration Systems (ERS) can obtain their primary energy source from renewable sources such as solar radiation, which transfers heat to the ERS generator to achieve optimal operation. Direct-expansion solar collectors have been gain attention in systems such as solar heat pumps, avoiding the use of additional subsystems and energy sources and reducing costs and electricity consumption. In this study, the dynamic performance of an ERS with direct-expansion solar generator is assessed by means of a validated mathematical model that couples ERS subsystem operation. The proposed model predicts the global behavior of the cycle by describing mass, momentum and energy transport in each subsystem and by coupling their inlet and outlet conditions. An ERS basic design for average meteorological condition with direct-expansion solar generator is numerically analyzed for different transient operating conditions, in terms of solar radiation and ambient temperature, obtained from the typical meteorological year (TMY) of Mexico City. The results show that in favorable environmental conditions, the system can operate 2.3 h longer than the average day because the generator can maintain the refrigerant vapor phase for a longer period. However, refrigerant overheating increases, causing a reduction in the entrainment ratio (ER) and coefficient of performance (COP). This study shows that the ERS with a direct-expansion solar generator can operate for more than 90% of the TMY, reaching ER values of up to 0.6 and COP of up to 0.5, which are close to conventional ERS.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"183 ","pages":"Pages 1-14"},"PeriodicalIF":3.8,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145883288","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}
Ejector refrigeration attracts more attention due to the intense increase of space cooling requirements and energy crises. Significant irreversibility inside the ejector hinders its applications by lowering ejector efficiency and system performance. Thus, it is important to understand the distribution of irreversibility inside the ejector and the effects of operating conditions and ejector geometries on irreversibility. A two-dimensional numerical model is developed considering direct entropy analysis method and real gas refrigerant property. Zeotropic mixture R134a/R32 is selected. Effects of primary and secondary flow pressure, ejector back pressure, nozzle throat and mixing chamber diameter on three types of entropy generation within the ejector are investigated. Results show that the turbulent dissipation entropy generation dominates the total entropy generation in all cases. As the primary flow pressure varies from 2588.80 kPa to 3188.80 kPa, the entrainment ratio first increases from 0.127 to 0.461 and then decreases to 0.400. The direct dissipation entropy generation mainly occurs in the divergent part of the nozzle and the mixing chamber, while the heat transfer entropy generation mainly occurs in the mixing shear layer and where the shock train occurs. As the secondary flow pressure changes from 334.61 kPa to 494.61 kPa, the entrainment ratio increases from 0.155 to 0.589, and the turbulent dissipation entropy generation decreases from 3.557 W/K to 2.667 W/K and then remains almost constant. As the ejector back pressure changes from 726.57 kPa to 900.57 kPa, the minimum total entropy generation is achieved at critical point.
{"title":"Study on irreversibility in an ejector with zeotropic mixtures using direct entropy analysis method","authors":"Zhengshu Dai , Jiaxin Xiang , Shuai Qin , Hua Zhang","doi":"10.1016/j.ijrefrig.2025.12.032","DOIUrl":"10.1016/j.ijrefrig.2025.12.032","url":null,"abstract":"<div><div>Ejector refrigeration attracts more attention due to the intense increase of space cooling requirements and energy crises. Significant irreversibility inside the ejector hinders its applications by lowering ejector efficiency and system performance. Thus, it is important to understand the distribution of irreversibility inside the ejector and the effects of operating conditions and ejector geometries on irreversibility. A two-dimensional numerical model is developed considering direct entropy analysis method and real gas refrigerant property. Zeotropic mixture R134a/R32 is selected. Effects of primary and secondary flow pressure, ejector back pressure, nozzle throat and mixing chamber diameter on three types of entropy generation within the ejector are investigated. Results show that the turbulent dissipation entropy generation dominates the total entropy generation in all cases. As the primary flow pressure varies from 2588.80 kPa to 3188.80 kPa, the entrainment ratio first increases from 0.127 to 0.461 and then decreases to 0.400. The direct dissipation entropy generation mainly occurs in the divergent part of the nozzle and the mixing chamber, while the heat transfer entropy generation mainly occurs in the mixing shear layer and where the shock train occurs. As the secondary flow pressure changes from 334.61 kPa to 494.61 kPa, the entrainment ratio increases from 0.155 to 0.589, and the turbulent dissipation entropy generation decreases from 3.557 W/K to 2.667 W/K and then remains almost constant. As the ejector back pressure changes from 726.57 kPa to 900.57 kPa, the minimum total entropy generation is achieved at critical point.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"183 ","pages":"Pages 108-122"},"PeriodicalIF":3.8,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923294","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}
Pub Date : 2025-12-29DOI: 10.1016/j.ijrefrig.2025.12.033
Ali M. Ashour , Saif Ali Kadhim , Osama B. Ahmed , Walid Aich , Kaouther Ghachem , Farhan Lafta Rashid , Karrar A. Hammoodi
Energy efficiency and waste heat recovery have become crucial challenges in refrigeration technology, especially with the increasing demand for sustainable and environmentally friendly cooling systems. In this paper, a hybrid thermoelectric generator system and vapor compression refrigeration, operated with R600a refrigerant, are analyzed with respect to utilizing waste heat sources as a means of generating electric power and enhancing the system’s efficacy. The experimental setup consists of a conventional vapor compression refrigeration cycle combined with thermoelectric generator modules between an aluminum cooling block. The experimental setup includes varying cooling water rates, ranging from 0.5 to 3.0 L/min, and condenser temperatures of 35 °C, 40 °C, and 45 °C to examine the influence of operating conditions on both thermal and electrical performance. The findings reveal that increasing water flow dramatically enhances cold-side heat transfer, resulting in a 40 °C temperature difference across the TEG, measured at a 45 °C condenser temperature, compared to 22.5 °C. Therefore, the electrical power output fluctuates from 0.05 W to 1.05 W, and the TEG efficiency reaches up to 2.2%, which is comparable to the best commercially available bismuth-telluride modules. The compressor pressure ratio and discharge temperature are reduced by 10% and 5 °C, respectively, which increases the system’s COP improvement to 7.9% and approximately 8% of total energy recovery. These findings confirm the thermodynamic benefit of TEG integration functioning as a desuperheating system for simultaneous cooling, power generation, and energy recovery.
{"title":"Experimental investigation of a vapor compression refrigeration system integrated with thermoelectric generators for enhanced energy recovery","authors":"Ali M. Ashour , Saif Ali Kadhim , Osama B. Ahmed , Walid Aich , Kaouther Ghachem , Farhan Lafta Rashid , Karrar A. Hammoodi","doi":"10.1016/j.ijrefrig.2025.12.033","DOIUrl":"10.1016/j.ijrefrig.2025.12.033","url":null,"abstract":"<div><div>Energy efficiency and waste heat recovery have become crucial challenges in refrigeration technology, especially with the increasing demand for sustainable and environmentally friendly cooling systems. In this paper, a hybrid thermoelectric generator system and vapor compression refrigeration, operated with R600a refrigerant, are analyzed with respect to utilizing waste heat sources as a means of generating electric power and enhancing the system’s efficacy. The experimental setup consists of a conventional vapor compression refrigeration cycle combined with thermoelectric generator modules between an aluminum cooling block. The experimental setup includes varying cooling water rates, ranging from 0.5 to 3.0 L/min, and condenser temperatures of 35 °C, 40 °C, and 45 °C to examine the influence of operating conditions on both thermal and electrical performance. The findings reveal that increasing water flow dramatically enhances cold-side heat transfer, resulting in a 40 °C temperature difference across the TEG, measured at a 45 °C condenser temperature, compared to 22.5 °C. Therefore, the electrical power output fluctuates from 0.05 W to 1.05 W, and the TEG efficiency reaches up to 2.2%, which is comparable to the best commercially available bismuth-telluride modules. The compressor pressure ratio and discharge temperature are reduced by 10% and 5 °C, respectively, which increases the system’s COP improvement to 7.9% and approximately 8% of total energy recovery. These findings confirm the thermodynamic benefit of TEG integration functioning as a desuperheating system for simultaneous cooling, power generation, and energy recovery.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"183 ","pages":"Pages 15-29"},"PeriodicalIF":3.8,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923227","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}
Pub Date : 2025-12-28DOI: 10.1016/j.ijrefrig.2025.12.031
Wenzhang Chen, Qiuhong Wang, Yifan Li, Hao Yin
The elastocaloric refrigeration, utilizing the elastocaloric effect of NiTi shape memory alloys (SMA), presents a promising environmentally sustainable alternative to the traditional vapor compression refrigeration. Optimizing system performance is crucial for maximizing efficiency but hindered by experimental complexity. This study addresses the challenge by developing an experimentally validated, generalizable thermo-fluid-mechanical coupling numerical model and an accompanying optimization framework. Systematic simulations are performed to investigate the coupled influence of operating frequency, heat transfer fluid velocity, temperature span, and fluid channel thickness on specific cooling power (SCP). Results demonstrate a non-monotonic dependence of SCP on both frequency and fluid velocity across different temperature spans and fluid channel thicknesses, revealing an optimal combination that maximizes SCP by balancing heat transfer and heat-regeneration efficiency. Additionally, this work introduces the normalized specific cooling power (NSCP) and then presents non-dimensional design principles for refrigeration systems that simultaneously incorporate thickness and temperature span through the optimization approach. The approach offers a novel and efficient (200 times faster) paradigm for designing and optimizing high-performance elastocaloric refrigeration systems with diverse refrigerants and system configurations, and successfully achieving a predicted NSCP that is at least 3 times higher than the existing experimental measurements.
{"title":"Cooling performance optimization of tubular elastocaloric regenerators via thermo-fluid-mechanical coupled numerical modeling and simulations","authors":"Wenzhang Chen, Qiuhong Wang, Yifan Li, Hao Yin","doi":"10.1016/j.ijrefrig.2025.12.031","DOIUrl":"10.1016/j.ijrefrig.2025.12.031","url":null,"abstract":"<div><div>The elastocaloric refrigeration, utilizing the elastocaloric effect of NiTi shape memory alloys (SMA), presents a promising environmentally sustainable alternative to the traditional vapor compression refrigeration. Optimizing system performance is crucial for maximizing efficiency but hindered by experimental complexity. This study addresses the challenge by developing an experimentally validated, generalizable thermo-fluid-mechanical coupling numerical model and an accompanying optimization framework. Systematic simulations are performed to investigate the coupled influence of operating frequency, heat transfer fluid velocity, temperature span, and fluid channel thickness on specific cooling power (SCP). Results demonstrate a non-monotonic dependence of SCP on both frequency and fluid velocity across different temperature spans and fluid channel thicknesses, revealing an optimal combination that maximizes SCP by balancing heat transfer and heat-regeneration efficiency. Additionally, this work introduces the normalized specific cooling power (NSCP) and then presents non-dimensional design principles for refrigeration systems that simultaneously incorporate thickness and temperature span through the optimization approach. The approach offers a novel and efficient (200 times faster) paradigm for designing and optimizing high-performance elastocaloric refrigeration systems with diverse refrigerants and system configurations, and successfully achieving a predicted NSCP that is at least 3 times higher than the existing experimental measurements.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"183 ","pages":"Pages 199-209"},"PeriodicalIF":3.8,"publicationDate":"2025-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923222","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}
Pub Date : 2025-12-28DOI: 10.1016/j.ijrefrig.2025.12.030
Irna Farikhah, Ammar M. Bahman
The escalating demand for cooling in hot climate regions, driven by rising global temperatures and rapid urbanization, underscores the urgent need for sustainable and efficient refrigeration technologies. Conventional vapor-compression systems, reliant on electricity and high-global-warming-potential refrigerants, are ill-suited for off-grid and high-ambient-temperature environments. Heat-driven thermoacoustic cooler (HDTCs) present a promising alternative, leveraging thermal energy from solar, waste, or combustion heat to generate acoustic waves that produce a refrigeration effect without moving parts or harmful refrigerants. This review provides a comprehensive analysis of recent advancements in HDTC technology, with a specific emphasis on their potential for hot-climate applications. It synthesizes progress in system design—from standing-wave to advanced multi-stage traveling-wave configurations—scaling, and the optimization of stack materials and geometries. The paper further explores technological applications across cryogenics, LNG, industry, buildings, and transportation, with a dedicated focus on hot-climate technologies such as off-grid cooling, desalination, and solar integration. Despite significant achievements, including coefficients of performance (COP) exceeding 3.0 in simulations and experimental exergy efficiencies up to 21%, a persistent gap remains between theoretical predictions and practical performance. Key challenges such as acoustic losses, phase mismatch, and material limitations are discussed, alongside future research directions aimed at enhancing efficiency, scalability, and reliability. The review concludes that HDTCs are poised for practical deployment and can become a cornerstone for sustainable, grid-resilient cooling in hot-climate regions, pending further research to bridge the performance gap and optimize real-world operation.
{"title":"Heat-driven thermoacoustic cooling technologies: A comprehensive review and future prospects for hot climate applications","authors":"Irna Farikhah, Ammar M. Bahman","doi":"10.1016/j.ijrefrig.2025.12.030","DOIUrl":"10.1016/j.ijrefrig.2025.12.030","url":null,"abstract":"<div><div>The escalating demand for cooling in hot climate regions, driven by rising global temperatures and rapid urbanization, underscores the urgent need for sustainable and efficient refrigeration technologies. Conventional vapor-compression systems, reliant on electricity and high-global-warming-potential refrigerants, are ill-suited for off-grid and high-ambient-temperature environments. Heat-driven thermoacoustic cooler (HDTCs) present a promising alternative, leveraging thermal energy from solar, waste, or combustion heat to generate acoustic waves that produce a refrigeration effect without moving parts or harmful refrigerants. This review provides a comprehensive analysis of recent advancements in HDTC technology, with a specific emphasis on their potential for hot-climate applications. It synthesizes progress in system design—from standing-wave to advanced multi-stage traveling-wave configurations—scaling, and the optimization of stack materials and geometries. The paper further explores technological applications across cryogenics, LNG, industry, buildings, and transportation, with a dedicated focus on hot-climate technologies such as off-grid cooling, desalination, and solar integration. Despite significant achievements, including coefficients of performance (COP) exceeding 3.0 in simulations and experimental exergy efficiencies up to 21%, a persistent gap remains between theoretical predictions and practical performance. Key challenges such as acoustic losses, phase mismatch, and material limitations are discussed, alongside future research directions aimed at enhancing efficiency, scalability, and reliability. The review concludes that HDTCs are poised for practical deployment and can become a cornerstone for sustainable, grid-resilient cooling in hot-climate regions, pending further research to bridge the performance gap and optimize real-world operation.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"183 ","pages":"Pages 153-187"},"PeriodicalIF":3.8,"publicationDate":"2025-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923229","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}
Pub Date : 2025-12-26DOI: 10.1016/j.ijrefrig.2025.12.029
Muhammad Shad, Xiaoqing Zhang
Miniature Stirling cryocoolers are vital for modern high-temperature Infrared (IR) detectors due to their precise cooling and SWaP (Size, Weight, and Power) compliance. This study proposes an integrated ANN-based multi-objective genetic algorithm (MOGA) optimization model with technique for order preference by similarity to ideal solution (TOPSIS) decision-making approach to optimize the coefficient of performance (COP) and work input (Winput) of a SWaP-refined Stirling cryocooler. According to the 2nd-order semi-adiabatic thermodynamics model (SATM) analysis, the design parameters, including motor rotational speed (RPM), phase angle between the piston and displacer (ϕ), working fluid initial charging pressure (Po), cooling temperature (Te), and piston stoke (Xp), have a significant impact on the COP and Winput of the SWaP-refined cryocooler, and therefore, optimization is required. Using a dataset from the SATM model based on SWaP constraints, a MOGA integrated with an ANN-trained model is applied to optimize these design parameters for the maximum COP and minimum Winput. A 100 optimized solutions were generated using the MOGA Pareto front, with the best optimized solution identified through the TOPSIS decision-making approach. At the TOPSIS closeness coefficient of Ci= 0.741, the relative errors between the ANN-MOGA results and the semi-adiabatic thermodynamic model are 2.9% for COP and 5% for Winput. With overall prediction errors less than 5%, the proposed integrated ANN-based MOGA optimization model offers an efficient and reliable approach for optimizing the design parameters and performance of SWaP-configured miniature Stirling cryocoolers.
微型斯特林制冷机由于其精确的冷却和SWaP（尺寸，重量和功率）合规性，对于现代高温红外（IR）探测器至关重要。提出了一种基于人工神经网络的多目标遗传算法（MOGA）优化模型，并结合TOPSIS （order preference by similarity to ideal solution）决策方法对swap改进的斯特林制冷机的性能系数（COP）和功输入（Winput）进行优化。根据二阶半绝热热力学模型（SATM）分析，电机转速（RPM）、活塞与置换器相位角（φ）、工作流体初始增压压力（Po）、冷却温度（Te）、活塞行程（Xp）等设计参数对swap精馏制冷机的COP和Winput有较大影响，需要对其进行优化。利用基于SWaP约束的SATM模型数据集，将MOGA与人工神经网络训练模型相结合，对这些设计参数进行优化，以获得最大COP和最小Winput。利用MOGA Pareto前沿生成了100个优化方案，并通过TOPSIS决策方法确定了最佳优化方案。在TOPSIS接近系数Ci = 0.741时，COP和Winput的ANN-MOGA结果与半绝热热力学模型的相对误差分别为2.9%和5%。该模型总体预测误差小于5%，为swap配置的微型斯特林制冷机的设计参数和性能优化提供了一种高效可靠的方法。
{"title":"Multi-objective optimization of a SWaP-refined miniature Stirling cryocooler using an integrated ANN-Genetic algorithm-based decision-making approach","authors":"Muhammad Shad, Xiaoqing Zhang","doi":"10.1016/j.ijrefrig.2025.12.029","DOIUrl":"10.1016/j.ijrefrig.2025.12.029","url":null,"abstract":"<div><div>Miniature Stirling cryocoolers are vital for modern high-temperature Infrared (IR) detectors due to their precise cooling and SWaP (Size, Weight, and Power) compliance. This study proposes an integrated ANN-based multi-objective genetic algorithm (MOGA) optimization model with technique for order preference by similarity to ideal solution (TOPSIS) decision-making approach to optimize the coefficient of performance (<em>COP</em>) and work input (<em>W</em><sub>input</sub>) of a SWaP-refined Stirling cryocooler. According to the 2nd-order semi-adiabatic thermodynamics model (SATM) analysis, the design parameters, including motor rotational speed (<em>RPM),</em> phase angle between the piston and displacer (<em>ϕ),</em> working fluid initial charging pressure (<em>P</em><sub>o</sub><em>),</em> cooling temperature (<em>T</em><sub>e</sub>)<em>,</em> and piston stoke (<em>X</em><sub>p</sub>), have a significant impact on the <em>COP</em> and <em>W</em><sub>input</sub> of the SWaP-refined cryocooler, and therefore, optimization is required. Using a dataset from the SATM model based on SWaP constraints, a MOGA integrated with an ANN-trained model is applied to optimize these design parameters for the maximum <em>COP</em> and minimum <em>W</em><sub>input</sub>. A 100 optimized solutions were generated using the MOGA Pareto front, with the best optimized solution identified through the TOPSIS decision-making approach. At the TOPSIS closeness coefficient of <em>C</em><sub>i</sub> <em>=</em> 0.741, the relative errors between the ANN-MOGA results and the semi-adiabatic thermodynamic model are 2.9% for <em>COP</em> and 5% for <em>W</em><sub>input</sub>. With overall prediction errors less than 5%, the proposed integrated ANN-based MOGA optimization model offers an efficient and reliable approach for optimizing the design parameters and performance of SWaP-configured miniature Stirling cryocoolers.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"183 ","pages":"Pages 210-220"},"PeriodicalIF":3.8,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923224","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}
Pub Date : 2025-12-24DOI: 10.1016/j.ijrefrig.2025.12.026
B. Manoj, U.C. Arunachala, H.S. Arunkumar
In the vapor compression air conditioning system, a notable amount of heat dissipation is obvious. The condenser plays a critical role in maintaining the refrigerant phase prior to the expansion valve. Previous studies have primarily focused on recovering waste heat through conventional thermal routes. However, in automobiles and other allied fields, in addition to process heat, direct energy conversion techniques are also in practice. Hence, the present experimental study is an attempt to demonstrate the implementation of both electrical and thermal routes to extract waste heat to the maximum possible extent from the air conditioning system. For this exercise, Coolselector software was used to fetch the operating conditions, (including tonnages of 1.5 TR, 3.0 TR, and 4.5 TR) and later, the entire operations were simulated. The thermoelectric generator (TEG) array produced a decent level of electrical power with negligible drop in process fluid temperature. In the double pipe heat exchanger (DPHX), the secondary side could extract a good amount of heat. Hence to identify the best-case, exergy analysis was done separately for the TEG and the DPHX, in that the 3.0 TR case identified as the best. Further, to enhance system performance, inserts were used in the DPHX, resulting in 26% and 46% improvement in effectiveness for louvered tape and twisted tape configurations, respectively. Even condenser length optimization was carried out to understand the influence of various heat transfer augmentation techniques. Though this approach is still in the pre-mature stage, appropriate design of condensers, heat spreaders, and heat exchangers can yield remarkable results.
{"title":"Concept of Integrating Air Conditioning System with Thermoelectric Units and Double-Pipe Heat Exchanger for Efficient Waste Heat Utilization: An Experimental study","authors":"B. Manoj, U.C. Arunachala, H.S. Arunkumar","doi":"10.1016/j.ijrefrig.2025.12.026","DOIUrl":"10.1016/j.ijrefrig.2025.12.026","url":null,"abstract":"<div><div>In the vapor compression air conditioning system, a notable amount of heat dissipation is obvious. The condenser plays a critical role in maintaining the refrigerant phase prior to the expansion valve. Previous studies have primarily focused on recovering waste heat through conventional thermal routes. However, in automobiles and other allied fields, in addition to process heat, direct energy conversion techniques are also in practice. Hence, the present experimental study is an attempt to demonstrate the implementation of both electrical and thermal routes to extract waste heat to the maximum possible extent from the air conditioning system. For this exercise, Coolselector software was used to fetch the operating conditions, (including tonnages of 1.5 TR, 3.0 TR, and 4.5 TR) and later, the entire operations were simulated. The thermoelectric generator (TEG) array produced a decent level of electrical power with negligible drop in process fluid temperature. In the double pipe heat exchanger (DPHX), the secondary side could extract a good amount of heat. Hence to identify the best-case, exergy analysis was done separately for the TEG and the DPHX, in that the 3.0 TR case identified as the best. Further, to enhance system performance, inserts were used in the DPHX, resulting in 26% and 46% improvement in effectiveness for louvered tape and twisted tape configurations, respectively. Even condenser length optimization was carried out to understand the influence of various heat transfer augmentation techniques. Though this approach is still in the pre-mature stage, appropriate design of condensers, heat spreaders, and heat exchangers can yield remarkable results.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"183 ","pages":"Pages 241-253"},"PeriodicalIF":3.8,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923226","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}
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