Pub Date : 2026-02-01Epub Date: 2025-11-11DOI: 10.1016/j.ijrefrig.2025.10.027
Francesco Fabris , Wasim Shah , Sergio Marinetti , Silvia Minetto , Antonio Rossetti
The transport refrigeration industry predominantly relies on mechanical vapor compression systems, which still use refrigerants with high environmental impact, for both long and short distance transportation. In short distance application, the integration of thermal energy storage (TES) and the use of natural refrigerants represent a promising path in reducing the environmental impact of the sector. This paper presents an innovative indirect expansion refrigeration system utilizing natural refrigerants (R290 and R744) to freeze eutectic plates, located inside an insulated box, designed for last-mile delivery of frozen food. A numerical model is developed and first validated against experimental data available for the baseline R452A solution, achieving a -1.2% error on the estimated energy consumption over the entire pulldown. When considering the new system, numerical simulations of a 36-hours pulldown show that, despite delivering the same cooling energy to the eutectic plates (-0.6 % compared to the baseline), the R290-R744 system can achieve a better distribution of the cooling effect in the eutectic plates, avoiding subcooling. During a 36-hours pulldown, the R290-R744 can perform with the same overall COP (0.79). However, on an annual basis, the use of natural refrigerants instead of synthetics allows achieving a reduction of the system overall carbon footprint equal to -69.6%.
{"title":"A novel propane – CO2 refrigeration system for mobile insulated boxes in last mile delivery","authors":"Francesco Fabris , Wasim Shah , Sergio Marinetti , Silvia Minetto , Antonio Rossetti","doi":"10.1016/j.ijrefrig.2025.10.027","DOIUrl":"10.1016/j.ijrefrig.2025.10.027","url":null,"abstract":"<div><div>The transport refrigeration industry predominantly relies on mechanical vapor compression systems, which still use refrigerants with high environmental impact, for both long and short distance transportation. In short distance application, the integration of thermal energy storage (TES) and the use of natural refrigerants represent a promising path in reducing the environmental impact of the sector. This paper presents an innovative indirect expansion refrigeration system utilizing natural refrigerants (R290 and R744) to freeze eutectic plates, located inside an insulated box, designed for last-mile delivery of frozen food. A numerical model is developed and first validated against experimental data available for the baseline R452A solution, achieving a -1.2% error on the estimated energy consumption over the entire pulldown. When considering the new system, numerical simulations of a 36-hours pulldown show that, despite delivering the same cooling energy to the eutectic plates (-0.6 % compared to the baseline), the R290-R744 system can achieve a better distribution of the cooling effect in the eutectic plates, avoiding subcooling. During a 36-hours pulldown, the R290-R744 can perform with the same overall COP (0.79). However, on an annual basis, the use of natural refrigerants instead of synthetics allows achieving a reduction of the system overall carbon footprint equal to -69.6%.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"182 ","pages":"Pages 159-168"},"PeriodicalIF":3.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145682298","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 : 2026-02-01Epub Date: 2025-12-16DOI: 10.1016/j.ijrefrig.2025.12.017
Yue Zheng , Hua Han , Jun Xiong , Hua Zhang , Xun Cao , Bo Gu , Wenjie Dai , Xu Gao , Weiqi Yi
Refrigerant leakage significantly undermines the energy efficiency and operational safety of variable refrigerant flow (VRF) systems, making accurate prediction of refrigerant charge critically important. Conventional diagnostic approaches are often costly, reliant on complex models, non-quantitative, and lack generalization, which restricts their practical deployment. To address these limitations, a series of enhancements and intelligent integration were introduced to the virtual refrigerant charge (VRC) sensor. An operating-condition matching strategy was first employed to establish an exVRC sensor for condition extending. An exponentially weighted moving average (EWMA) control chart was then incorporated to construct an exVRC-E sensor for oscillation mitigation. Finally, a deep learning-based Residual Neural Network (ResNet) was established and coupled with the exVRC-E sensor to produce an AI-knowledge dual-driven intelligent sensor, exVRC-ER. Experimental validation on a 33.5 kW VRF system under one rated and fourteen off-rated conditions showed that compared with the original VRC sensor, the exVRC sensor reduces MAPE by 16.21 % under extreme off-rated conditions, corresponding to a 74 % relative reduction. The exVRC-E sensor further lowers oscillation amplitude by 84 % and reduces false-alarm risk during normal operation. Across all conditions, the final exVRC-ER intelligent sensor integrated with deep learning achieves the best performance, with a 71.8 % relative reduction in MAPE and a 1.21 kg decrease in root mean square error (RMSE) compared with the original VRC sensor. These results indicate a significant potential for precise quantification of refrigerant leakage, highlighting their importance for enhancing the efficient operation and intelligent maintenance of HVAC systems.
{"title":"Improvements and intelligence integration of virtual refrigerant charge (VRC) sensor","authors":"Yue Zheng , Hua Han , Jun Xiong , Hua Zhang , Xun Cao , Bo Gu , Wenjie Dai , Xu Gao , Weiqi Yi","doi":"10.1016/j.ijrefrig.2025.12.017","DOIUrl":"10.1016/j.ijrefrig.2025.12.017","url":null,"abstract":"<div><div>Refrigerant leakage significantly undermines the energy efficiency and operational safety of variable refrigerant flow (VRF) systems, making accurate prediction of refrigerant charge critically important. Conventional diagnostic approaches are often costly, reliant on complex models, non-quantitative, and lack generalization, which restricts their practical deployment. To address these limitations, a series of enhancements and intelligent integration were introduced to the virtual refrigerant charge (VRC) sensor. An operating-condition matching strategy was first employed to establish an exVRC sensor for condition extending. An exponentially weighted moving average (EWMA) control chart was then incorporated to construct an exVRC-E sensor for oscillation mitigation. Finally, a deep learning-based Residual Neural Network (ResNet) was established and coupled with the exVRC-E sensor to produce an AI-knowledge dual-driven intelligent sensor, exVRC-ER. Experimental validation on a 33.5 kW VRF system under one rated and fourteen off-rated conditions showed that compared with the original VRC sensor, the exVRC sensor reduces MAPE by 16.21 % under extreme off-rated conditions, corresponding to a 74 % relative reduction. The exVRC-E sensor further lowers oscillation amplitude by 84 % and reduces false-alarm risk during normal operation. Across all conditions, the final exVRC-ER intelligent sensor integrated with deep learning achieves the best performance, with a 71.8 % relative reduction in MAPE and a 1.21 kg decrease in root mean square error (RMSE) compared with the original VRC sensor. These results indicate a significant potential for precise quantification of refrigerant leakage, highlighting their importance for enhancing the efficient operation and intelligent maintenance of HVAC systems.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"182 ","pages":"Pages 456-468"},"PeriodicalIF":3.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145786652","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 : 2026-02-01Epub Date: 2025-12-08DOI: 10.1016/j.ijrefrig.2025.12.009
Lingeng Zou , Fukang Yu , Tao Bai , Ye Liu
The integration of solar-driven ejector refrigeration cycles with conventional vapor-compression refrigeration cycles (VCRC) offers significant potential for energy conservation in air-conditioning systems. To enhance VCRC performance, this study proposes a solar-assisted hybrid ejector-compression refrigeration cycle (ECRC) that employs a subcooler to couple the ejector cycle with the VCRC, using the low-global-warming-potential (GWP) refrigerant R290. The ECRC employs a solar-driven ejector cycle to enhance the primary vapor compression cycle by increasing the subcooling degree, thereby improving system performance. This work theoretically investigates the ECRC performance compared to the standard VCRC via a comprehensive 4E (energy, exergy, economic, environmental) analysis. Results show that at the optimal intermediate temperature, optimized via the Particle Swarm Optimization algorithm, the ECRC achieves a 9.0 % improvement in coefficient of performance (COP) and a 15.1 % increase in volumetric cooling capacity (Qev) over the VCRC. Exergy analysis reveals that the generator accounts for approximately 47.4 % of total exergy destruction, indicating optimization potential. Economically, the ECRC reduces exergy production cost by 7.9–12.7 %, demonstrating better returns. Environmentally, the ECRC with R290 cuts carbon emissions by 7.90 % compared to the VCRC. Overall, the ECRC exhibits strong potential for sustainable air-conditioning applications.
{"title":"A modified solar-enhanced hybrid ejector-vapor compression cycle: Energy, exergy, economic, and environmental assessment","authors":"Lingeng Zou , Fukang Yu , Tao Bai , Ye Liu","doi":"10.1016/j.ijrefrig.2025.12.009","DOIUrl":"10.1016/j.ijrefrig.2025.12.009","url":null,"abstract":"<div><div>The integration of solar-driven ejector refrigeration cycles with conventional vapor-compression refrigeration cycles (VCRC) offers significant potential for energy conservation in air-conditioning systems. To enhance VCRC performance, this study proposes a solar-assisted hybrid ejector-compression refrigeration cycle (ECRC) that employs a subcooler to couple the ejector cycle with the VCRC, using the low-global-warming-potential (GWP) refrigerant R290. The ECRC employs a solar-driven ejector cycle to enhance the primary vapor compression cycle by increasing the subcooling degree, thereby improving system performance. This work theoretically investigates the ECRC performance compared to the standard VCRC via a comprehensive 4E (energy, exergy, economic, environmental) analysis. Results show that at the optimal intermediate temperature, optimized via the Particle Swarm Optimization algorithm, the ECRC achieves a 9.0 % improvement in coefficient of performance (COP) and a 15.1 % increase in volumetric cooling capacity (<em>Q</em><sub>ev</sub>) over the VCRC. Exergy analysis reveals that the generator accounts for approximately 47.4 % of total exergy destruction, indicating optimization potential. Economically, the ECRC reduces exergy production cost by 7.9–12.7 %, demonstrating better returns. Environmentally, the ECRC with R290 cuts carbon emissions by 7.90 % compared to the VCRC. Overall, the ECRC exhibits strong potential for sustainable air-conditioning applications.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"182 ","pages":"Pages 334-348"},"PeriodicalIF":3.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733331","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 : 2026-02-01Epub Date: 2025-11-23DOI: 10.1016/j.ijrefrig.2025.11.024
Francesco Fabris , Wasim Shah , Sergio Marinetti , Silvia Minetto , Antonio Rossetti
To meet the upcoming challenge of environmental sustainability, refrigerated transport is required to address energy efficiency and use sustainable fluids, namely natural refrigerants, at the same time taking into consideration the typical constraints of mobile systems, i.e. space and weight, system complexity, reliability and ease of servicing and maintenance. In this study, the design of a R744 refrigeration system employed on a light commercial vehicle used for urban delivery of fresh products (4-5 kW at 0°C) is considered. The effects of different system architectures, controls and components are numerically evaluated focusing on the trade-off between the increase of the unit complexity, leading to higher energy efficiency of the sole cooling system, and the decrease of the unit overall encumbrance and weight, leading to lower carbon footprint of the vehicle.
Numerical results show that the use of an ejector can enhance the unit COP up to +28.6% for high ambient temperature conditions (40°C). A compact unit design based on the use of a light and efficient variable-speed scroll compressor leads to a reduction in carbon emissions of an average delivery mission between -17.9% and -34.4%, depending on climatic conditions. The effects of evaporator sizing on the system performance and emissions are discussed. The overall carbon footprint of the units over their entire life cycle is assessed, highlighting that more than 95% of the equivalent CO2 emissions are related to system operation. The use of natural refrigerant R744 reduces the direct leakage emissions to negligible values.
{"title":"Numerical assessment of the influence of a R744 cooling unit design and components on the overall carbon footprint of a light refrigerated vehicle","authors":"Francesco Fabris , Wasim Shah , Sergio Marinetti , Silvia Minetto , Antonio Rossetti","doi":"10.1016/j.ijrefrig.2025.11.024","DOIUrl":"10.1016/j.ijrefrig.2025.11.024","url":null,"abstract":"<div><div>To meet the upcoming challenge of environmental sustainability, refrigerated transport is required to address energy efficiency and use sustainable fluids, namely natural refrigerants, at the same time taking into consideration the typical constraints of mobile systems, i.e. space and weight, system complexity, reliability and ease of servicing and maintenance. In this study, the design of a R744 refrigeration system employed on a light commercial vehicle used for urban delivery of fresh products (4-5 kW at 0°C) is considered. The effects of different system architectures, controls and components are numerically evaluated focusing on the trade-off between the increase of the unit complexity, leading to higher energy efficiency of the sole cooling system, and the decrease of the unit overall encumbrance and weight, leading to lower carbon footprint of the vehicle.</div><div>Numerical results show that the use of an ejector can enhance the unit COP up to +28.6% for high ambient temperature conditions (40°C). A compact unit design based on the use of a light and efficient variable-speed scroll compressor leads to a reduction in carbon emissions of an average delivery mission between -17.9% and -34.4%, depending on climatic conditions. The effects of evaporator sizing on the system performance and emissions are discussed. The overall carbon footprint of the units over their entire life cycle is assessed, highlighting that more than 95% of the equivalent CO<sub>2</sub> emissions are related to system operation. The use of natural refrigerant R744 reduces the direct leakage emissions to negligible values.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"182 ","pages":"Pages 137-146"},"PeriodicalIF":3.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145682301","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 : 2026-02-01Epub Date: 2025-12-12DOI: 10.1016/j.ijrefrig.2025.12.013
Anjelina W Mwakosya, Graciela Alvarez, Fatou Toutie Ndoye
This study aims to investigate the microstructure changes of partially frozen beef under different superchilling storage conditions and relate these changes to quality degradation. Beef samples were partially frozen in an air blast freezer with a heat transfer coefficient of 112 W/m2K and an air temperature of ‒32 °C for 2 min following storage at ‒1.8 °C, ‒2.8 °C, ‒4 °C and ‒5 °C for 21 days. "X-ray micro-computed tomography (µCT), a non-destructive 3D imaging technique was used to visualize and quantify ice crystal characteristic, including ice volume fractions, ice crystal size, number and distribution". Recrystallization kinetics were modelled using the asymptotic Ostwald ripening equation and correlated with quality degradation rate through Pearson correlation analysis. Immediately after partial freezing, the average initial ice volume fraction, mean equivalent diameter, and crystal number were 31 ± 1 %, 36.0 ± 0.3 µm, and 421,182 ± 16,524, respectively. Over storage time, ice volume fraction and crystal size increased significantly (p < 0.05), while crystal number decreased, leading to increased drip loss, and reduced firmness of beef upon thawing. In addition, recrystallization rates increased significantly (p < 0.05) with decreasing storage temperature specifically within a range of ‒1.8 °C to ‒5 °C as lower temperatures resulted in higher ice fractions and more heterogeneous crystal size distributions, thereby promoting recrystallization. A high regression coefficient (R2 > 0.9) indicated a strong fit of the recrystallization rate’s temperature dependence to the Arrhenius model. Recrystallization rate was strongly correlated with all quality degradation rates (R2 > 0.9). Overall, this study demonstrates the critical role of recrystallization in driving deterioration of partially frozen beef and highlights the value of X‒ray µCT for non-invasive monitoring microstructure changes during superchilled storage.
{"title":"Impact of superchilling storage temperatures on beef quality: Micro-CT analysis of ice recrystallization kinetics in partially frozen samples","authors":"Anjelina W Mwakosya, Graciela Alvarez, Fatou Toutie Ndoye","doi":"10.1016/j.ijrefrig.2025.12.013","DOIUrl":"10.1016/j.ijrefrig.2025.12.013","url":null,"abstract":"<div><div>This study aims to investigate the microstructure changes of partially frozen beef under different superchilling storage conditions and relate these changes to quality degradation. Beef samples were partially frozen in an air blast freezer with a heat transfer coefficient of 112 W/m<sup>2</sup>K and an air temperature of ‒32 °C for 2 min following storage at ‒1.8 °C, ‒2.8 °C, ‒4 °C and ‒5 °C for 21 days. \"X-ray micro-computed tomography (µCT), a non-destructive 3D imaging technique was used to visualize and quantify ice crystal characteristic, including ice volume fractions, ice crystal size, number and distribution\". Recrystallization kinetics were modelled using the asymptotic Ostwald ripening equation and correlated with quality degradation rate through Pearson correlation analysis. Immediately after partial freezing, the average initial ice volume fraction, mean equivalent diameter, and crystal number were 31 ± 1 %, 36.0 ± 0.3 µm, and 421,182 ± 16,524, respectively. Over storage time, ice volume fraction and crystal size increased significantly (<em>p</em> < 0.05), while crystal number decreased, leading to increased drip loss, and reduced firmness of beef upon thawing. In addition, recrystallization rates increased significantly (<em>p</em> < 0.05) with decreasing storage temperature specifically within a range of ‒1.8 °C to ‒5 °C as lower temperatures resulted in higher ice fractions and more heterogeneous crystal size distributions, thereby promoting recrystallization. A high regression coefficient (R<sup>2</sup> > 0.9) indicated a strong fit of the recrystallization rate’s temperature dependence to the Arrhenius model. Recrystallization rate was strongly correlated with all quality degradation rates (R<sup>2</sup> > 0.9). Overall, this study demonstrates the critical role of recrystallization in driving deterioration of partially frozen beef and highlights the value of X‒ray µCT for non-invasive monitoring microstructure changes during superchilled storage.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"182 ","pages":"Pages 418-429"},"PeriodicalIF":3.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145786653","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 : 2026-02-01Epub Date: 2025-12-10DOI: 10.1016/j.ijrefrig.2025.12.012
Sujie Liu , Jiaxuan Pu , Jiaxing Li , Huan Zhang , Tianzhen Ye , Xinyu Zhang , Zhihao Wan , Zhaoying Wang , Xianwang Fan , Wandong Zheng
The ongoing integration of renewable energy into power grids is driving a transition towards distributed and multi-source energy frameworks in building energy systems. Solar-assisted heat pumps, as the emerging distributed multi-source heating systems, face persistent challenges including operating instability, seasonal limitations, and complex control requirements. To address these shortcomings, this study develops a novel integrated unglazed solar-air dual-source heat pump (USAHP) system. The system synergistically harnesses dual renewable energy sources by incorporating high-efficiency finned tubes with absorbing coating and reflectors into a compound solar air collector-evaporator. The integration could maximize evaporator output within a constrained area. Experimental investigations are conducted to evaluate and analyze the system performance, specifically examining the effects of operating parameters and collector-evaporator configuration on thermal collection efficiency. Results demonstrate that among three key parameters, solar irradiance and ambient air temperature exert significantly positive influences on system performance, while relative humidity exhibits weak correlation. The reflector-equipped collector-evaporator enhances solar irradiance absorption by 27–54 %. The proposed USAHP achieves superior frost suppression and enhanced energy efficiency by elevating the evaporation temperature. The evaporation temperature of USAHP increases by up to 3.2 °C under experimental conditions, and COP improves by up to 19.3 % compared to conventional air-source and solar-air assisted heat pump systems. Furthermore, a payback period of 3.18 years demonstrates the economic viability of USAHP. This research represents key advancement in frost mitigation mechanisms and demonstrates substantial improvements in energy efficiency, thereby advancing heat pump technology for multi-source energy applications.
{"title":"Thermo-economic performance of an integrated unglazed solar-air dual-source heat pump: an experimental investigation","authors":"Sujie Liu , Jiaxuan Pu , Jiaxing Li , Huan Zhang , Tianzhen Ye , Xinyu Zhang , Zhihao Wan , Zhaoying Wang , Xianwang Fan , Wandong Zheng","doi":"10.1016/j.ijrefrig.2025.12.012","DOIUrl":"10.1016/j.ijrefrig.2025.12.012","url":null,"abstract":"<div><div>The ongoing integration of renewable energy into power grids is driving a transition towards distributed and multi-source energy frameworks in building energy systems. Solar-assisted heat pumps, as the emerging distributed multi-source heating systems, face persistent challenges including operating instability, seasonal limitations, and complex control requirements. To address these shortcomings, this study develops a novel integrated unglazed solar-air dual-source heat pump (USAHP) system. The system synergistically harnesses dual renewable energy sources by incorporating high-efficiency finned tubes with absorbing coating and reflectors into a compound solar air collector-evaporator. The integration could maximize evaporator output within a constrained area. Experimental investigations are conducted to evaluate and analyze the system performance, specifically examining the effects of operating parameters and collector-evaporator configuration on thermal collection efficiency. Results demonstrate that among three key parameters, solar irradiance and ambient air temperature exert significantly positive influences on system performance, while relative humidity exhibits weak correlation. The reflector-equipped collector-evaporator enhances solar irradiance absorption by 27–54 %. The proposed USAHP achieves superior frost suppression and enhanced energy efficiency by elevating the evaporation temperature. The evaporation temperature of USAHP increases by up to 3.2 °C under experimental conditions, and COP improves by up to 19.3 % compared to conventional air-source and solar-air assisted heat pump systems. Furthermore, a payback period of 3.18 years demonstrates the economic viability of USAHP. This research represents key advancement in frost mitigation mechanisms and demonstrates substantial improvements in energy efficiency, thereby advancing heat pump technology for multi-source energy applications.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"182 ","pages":"Pages 383-398"},"PeriodicalIF":3.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145786747","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 : 2026-02-01Epub Date: 2025-11-26DOI: 10.1016/j.ijrefrig.2025.11.026
P.R. Chauhan , S.K. Tyagi
Commercial adsorbents like silica gel, zeolite, and Maxsorb III have been widely studied for adsorption cooling. Recent focus has shifted towards biomass-based activated carbons, though hard lignocellulosic sources remain underexplored. This first-of-its-kind study introduces pistachio shell-derived activated carbon for cooling applications. The eco-friendly biosorbent is produced through a two-step process, slow pyrolysis and thermochemical activation, with optimized parameters: 562.5 °C and a 1:4 biochar-to-KOH ratio. The ethanol uptake measurements are performed using a customized adsorption setup at temperatures ranging from 20 °C to 80 °C, for evaporator temperatures of 5 °C, 10 °C, and 15 °C. The experimental adsorption performance has been modelled using the Dubinin-Astakhov isotherm, while a third-order polynomial equation is proposed to describe the temperature-dependent specific heat capacity of the prepared biosorbent. The performance analysis reveals that the optimum values of ethanol uptake, volumetric cooling energy, and COP are estimated as 42.71 kg m-3, 144.12 MJ m-3, and 0.7924, respectively, at a desorption temperature of 78.46 °C and evaporator pressure of 2.22 kPa. The proposed biosorbent–ethanol pair demonstrates strong potential compared to commercial adsorbents, based on a comprehensive assessment of porous properties, cooling performance, and cost-effectiveness. The novel entransy and destruction analysis further highlights that the desorber possesses the highest entransy, which decreases from 37.5 % to 30.1 % as evaporator pressure increases from 1.09 kPa to 4.28 kPa, indicating enhanced system efficiency with lower thermal input demand. With promising scalability, this sustainable biosorbent aligns with SDG 12 and SDG 13 by reducing environmental impact and supporting eco-friendly cooling solutions.
{"title":"Optimized biosorbent for ethanol sorption refrigeration: Adsorption kinetics, thermodynamic performance, and entransy evaluation","authors":"P.R. Chauhan , S.K. Tyagi","doi":"10.1016/j.ijrefrig.2025.11.026","DOIUrl":"10.1016/j.ijrefrig.2025.11.026","url":null,"abstract":"<div><div>Commercial adsorbents like silica gel, zeolite, and Maxsorb III have been widely studied for adsorption cooling. Recent focus has shifted towards biomass-based activated carbons, though hard lignocellulosic sources remain underexplored. This first-of-its-kind study introduces pistachio shell-derived activated carbon for cooling applications. The eco-friendly biosorbent is produced through a two-step process, slow pyrolysis and thermochemical activation, with optimized parameters: 562.5 °C and a 1:4 biochar-to-KOH ratio. The ethanol uptake measurements are performed using a customized adsorption setup at temperatures ranging from 20 °C to 80 °C, for evaporator temperatures of 5 °C, 10 °C, and 15 °C. The experimental adsorption performance has been modelled using the Dubinin-Astakhov isotherm, while a third-order polynomial equation is proposed to describe the temperature-dependent specific heat capacity of the prepared biosorbent. The performance analysis reveals that the optimum values of ethanol uptake, volumetric cooling energy, and COP are estimated as 42.71 kg m<sup>-3</sup>, 144.12 MJ m<sup>-3</sup>, and 0.7924, respectively, at a desorption temperature of 78.46 °C and evaporator pressure of 2.22 kPa. The proposed biosorbent–ethanol pair demonstrates strong potential compared to commercial adsorbents, based on a comprehensive assessment of porous properties, cooling performance, and cost-effectiveness. The novel entransy and destruction analysis further highlights that the desorber possesses the highest entransy, which decreases from 37.5 % to 30.1 % as evaporator pressure increases from 1.09 kPa to 4.28 kPa, indicating enhanced system efficiency with lower thermal input demand. With promising scalability, this sustainable biosorbent aligns with SDG 12 and SDG 13 by reducing environmental impact and supporting eco-friendly cooling solutions.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"182 ","pages":"Pages 169-187"},"PeriodicalIF":3.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145682310","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 : 2026-02-01Epub Date: 2025-11-21DOI: 10.1016/j.ijrefrig.2025.11.015
Ammar M. Bahman , Mohammad Erfanimatin , Pejman Nourani , Haotian Liu , Vatsal M. Shah , James E. Braun , Eckhard A. Groll
With the deployment of variable-speed compressors in unitary air conditioning (AC) systems as well as the future implementation of newer HFO refrigerants, there is a need to upgrade line sizing guidelines to account for the effects of oil retention (OR). These new guidelines can be facilitated through developing and applying a predictive model for OR in vapor lines for commonly used refrigerant-lubricant combinations in the heating, ventilation, air conditioning, and refrigeration (HVAC&R) industry. This work aims to evaluate the prediction accuracy of machine learning (ML), physics-based (PB), and hybrid models trained using OR data obtained for horizontal and vertical lines of different diameters (11, 17, and 20 mm). The data include different refrigerants (R134a, R410A, R32, and R1234ze(E)) used with POE32 lubricant under various flow conditions. The ML models were trained and tested using data obtained from over 230 experimental tests. The input parameters for each model were refrigerant conditions (type, temperature, pressure, and mass flow rate), pipeline dimensions and orientation, injected oil mass flow rate, and oil viscosity, with OR as the predicted output. Various model types were investigated and compared, including a purely physics-based (PB) model, two standalone ML models, and two physics-based machine learning-aided (PBMLA) algorithms. A sensitivity analysis was performed to assess the effect of input parameters on the prediction errors. In addition, an extrapolation study was conducted using different refrigerants and various oil grades and types to evaluate the models’ ability to predict OR with acceptable accuracy. The results showed that the standalone ML algorithms exhibited lower accuracy in predicting OR compared to the PB model. Furthermore, the PBMLA models demonstrated a modest improvement in OR prediction accuracy over the purely PB model (improved R2 by up to 10.8 %, and reduced RMSE by up to 4.5 %). Moreover, the parametric analysis revealed that the PBMLA models could address variations of the feature inputs relatively better than the PB model, leading to their higher prediction accuracy compared to all other models. Finally, the extrapolation analysis showed that both the PB and PBMLA models were not limited to specific oil types or grades, suggesting their potential for general applicability in OR prediction and system design.
{"title":"A hybrid physics-based machine learning framework for oil retention prediction: a comparative analysis of modeling approaches in refrigerant vapor lines","authors":"Ammar M. Bahman , Mohammad Erfanimatin , Pejman Nourani , Haotian Liu , Vatsal M. Shah , James E. Braun , Eckhard A. Groll","doi":"10.1016/j.ijrefrig.2025.11.015","DOIUrl":"10.1016/j.ijrefrig.2025.11.015","url":null,"abstract":"<div><div>With the deployment of variable-speed compressors in unitary air conditioning (AC) systems as well as the future implementation of newer HFO refrigerants, there is a need to upgrade line sizing guidelines to account for the effects of oil retention (OR). These new guidelines can be facilitated through developing and applying a predictive model for OR in vapor lines for commonly used refrigerant-lubricant combinations in the heating, ventilation, air conditioning, and refrigeration (HVAC&R) industry. This work aims to evaluate the prediction accuracy of machine learning (ML), physics-based (PB), and hybrid models trained using OR data obtained for horizontal and vertical lines of different diameters (11, 17, and 20 mm). The data include different refrigerants (R134a, R410A, R32, and R1234ze(E)) used with POE32 lubricant under various flow conditions. The ML models were trained and tested using data obtained from over 230 experimental tests. The input parameters for each model were refrigerant conditions (type, temperature, pressure, and mass flow rate), pipeline dimensions and orientation, injected oil mass flow rate, and oil viscosity, with OR as the predicted output. Various model types were investigated and compared, including a purely physics-based (PB) model, two standalone ML models, and two physics-based machine learning-aided (PBMLA) algorithms. A sensitivity analysis was performed to assess the effect of input parameters on the prediction errors. In addition, an extrapolation study was conducted using different refrigerants and various oil grades and types to evaluate the models’ ability to predict OR with acceptable accuracy. The results showed that the standalone ML algorithms exhibited lower accuracy in predicting OR compared to the PB model. Furthermore, the PBMLA models demonstrated a modest improvement in OR prediction accuracy over the purely PB model (improved R<sup>2</sup> by up to 10.8 %, and reduced RMSE by up to 4.5 %). Moreover, the parametric analysis revealed that the PBMLA models could address variations of the feature inputs relatively better than the PB model, leading to their higher prediction accuracy compared to all other models. Finally, the extrapolation analysis showed that both the PB and PBMLA models were not limited to specific oil types or grades, suggesting their potential for general applicability in OR prediction and system design.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"182 ","pages":"Pages 504-521"},"PeriodicalIF":3.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145836456","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 : 2026-02-01Epub Date: 2025-11-19DOI: 10.1016/j.ijrefrig.2025.11.017
Dewei Lv, Jie Lv, Qichao Yang, Yuanyang Zhao, Guangbin Liu, Liansheng Li
To improve the usability of the CO2 supermarket refrigeration system in warmer zones, two types of ejector-enhanced CO2 refrigeration systems (ECRS, DECRS) combining ejectors and subcooling to improve the system efficiency by subcooling and replacing the expansion valve are proposed as solutions. Three representative cities in China are selected and discussed in detail in energy, exergy and energy saving evaluation. The energy results illustrate that the ejectors significantly improve the system performance, and the higher the ambient temperature, the greater the performance improvement. At the ambient temperature of 45 °C, the maximum coefficient of performance (COPmax) of ECRS and DECRS is increased by 21.6 % and 26.3 %, compared to basic CO2 refrigeration system (BCRS). Using subcooling as well as further replacement of the expansion valve with ejector lead to a remarkable reduction of the irreversible loss of the system. In the transcritical zone, the exergy efficiency of ECRS and DECRS improves 11.9 % to 30.5 % and 13.7 % to 31.3 %, compared with BCRS. The energy saving evaluation demonstrates that compared with the annual performance factor of BCRS, in Guangzhou, ECRS can be increased by 5.1 %, and DECRS even reaches 7.1 %, which provides a solution and a certain theoretical basis for the use of ejector systems in supermarket system in warmer zones.
{"title":"Performance analysis and energy saving potential of an ejector-enhanced CO2 refrigeration system for supermarkets","authors":"Dewei Lv, Jie Lv, Qichao Yang, Yuanyang Zhao, Guangbin Liu, Liansheng Li","doi":"10.1016/j.ijrefrig.2025.11.017","DOIUrl":"10.1016/j.ijrefrig.2025.11.017","url":null,"abstract":"<div><div>To improve the usability of the CO<sub>2</sub> supermarket refrigeration system in warmer zones, two types of ejector-enhanced CO<sub>2</sub> refrigeration systems (ECRS, DECRS) combining ejectors and subcooling to improve the system efficiency by subcooling and replacing the expansion valve are proposed as solutions. Three representative cities in China are selected and discussed in detail in energy, exergy and energy saving evaluation. The energy results illustrate that the ejectors significantly improve the system performance, and the higher the ambient temperature, the greater the performance improvement. At the ambient temperature of 45 °C, the maximum coefficient of performance (COP<sub>max</sub>) of ECRS and DECRS is increased by 21.6 % and 26.3 %, compared to basic CO<sub>2</sub> refrigeration system (BCRS). Using subcooling as well as further replacement of the expansion valve with ejector lead to a remarkable reduction of the irreversible loss of the system. In the transcritical zone, the exergy efficiency of ECRS and DECRS improves 11.9 % to 30.5 % and 13.7 % to 31.3 %, compared with BCRS. The energy saving evaluation demonstrates that compared with the annual performance factor of BCRS, in Guangzhou, ECRS can be increased by 5.1 %, and DECRS even reaches 7.1 %, which provides a solution and a certain theoretical basis for the use of ejector systems in supermarket system in warmer zones.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"182 ","pages":"Pages 14-28"},"PeriodicalIF":3.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145571214","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 : 2026-02-01Epub Date: 2025-11-22DOI: 10.1016/j.ijrefrig.2025.11.022
Sannapareddy Anilkumar, E.Anil Kumar
Conventional vapor compression systems require significant electrical energy to achieve low evaporator temperatures, which limits their application in low-resource or off-grid scenarios. Sorption-based cooling systems offer a promising alternative by utilizing low-grade thermal energy, reducing dependency on electricity. This study investigates a two-bed thermochemical sorption system to overcome the inherent trade-off in single-bed systems, where achieving low evaporator temperatures typically demands high regeneration temperatures. Four high temperature salt (HTS) and medium temperature salt (MTS) pairs, MnCl2-SrCl2, MnCl2CaCl2, MgCl2-SrCl2, and MgCl2CaCl2 were selected using thermodynamic and kinetic data. Performance of these pairs with optimised two tube-bundle reactor configuration is evaluated using a transient numerical model. The two-bed system achieved evaporator temperatures down to -30 °C with regeneration temperatures as low as 130 °C. MnCl2-SrCl2 showed the highest overall performance of specific cooling power of 57 W/kg, cooling capacity of 854 W and coefficient of performance of 0.14, while MgCl2 pairs performance is low due to its slow kinetics. Overall, analysis revealed that limiting system operation to 70 % of the maximum sorption capacity improves energy efficiency by maintaining faster reaction rates.
{"title":"Performance study of a novel two-bed thermochemical cooling system for low temperature application: Modelling and Validation","authors":"Sannapareddy Anilkumar, E.Anil Kumar","doi":"10.1016/j.ijrefrig.2025.11.022","DOIUrl":"10.1016/j.ijrefrig.2025.11.022","url":null,"abstract":"<div><div>Conventional vapor compression systems require significant electrical energy to achieve low evaporator temperatures, which limits their application in low-resource or off-grid scenarios. Sorption-based cooling systems offer a promising alternative by utilizing low-grade thermal energy, reducing dependency on electricity. This study investigates a two-bed thermochemical sorption system to overcome the inherent trade-off in single-bed systems, where achieving low evaporator temperatures typically demands high regeneration temperatures. Four high temperature salt (HTS) and medium temperature salt (MTS) pairs, MnCl<sub>2</sub>-SrCl<sub>2</sub>, MnCl<sub>2</sub><sub><img></sub>CaCl<sub>2</sub>, MgCl<sub>2</sub>-SrCl<sub>2</sub>, and MgCl<sub>2</sub><sub><img></sub>CaCl<sub>2</sub> were selected using thermodynamic and kinetic data. Performance of these pairs with optimised two tube-bundle reactor configuration is evaluated using a transient numerical model. The two-bed system achieved evaporator temperatures down to -30 °C with regeneration temperatures as low as 130 °C. MnCl<sub>2</sub>-SrCl<sub>2</sub> showed the highest overall performance of specific cooling power of 57 W/kg, cooling capacity of 854 W and coefficient of performance of 0.14, while MgCl<sub>2</sub> pairs performance is low due to its slow kinetics. Overall, analysis revealed that limiting system operation to 70 % of the maximum sorption capacity improves energy efficiency by maintaining faster reaction rates.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"182 ","pages":"Pages 299-311"},"PeriodicalIF":3.8,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733324","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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