Pub Date : 2025-04-21DOI: 10.1016/j.ijrefrig.2025.03.037
F. Vidan-Falomir, R. Larrondo-Sancho, D. Sánchez, R. Cabello
Carbon dioxide (CO2) 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.
{"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}
Pub Date : 2025-04-17DOI: 10.1016/j.ijrefrig.2025.03.040
Faramarz Ilamidoshmanziari, Long Ni
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-1 to 0.036 kg.s-1 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.
{"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}
Pub Date : 2025-04-15DOI: 10.1016/j.ijrefrig.2025.04.010
Xiaocui Li , Liang Zhang , Xiaofeng Xu
This paper presents a refrigeration experimental platform that can switch between a two-stage transcritical CO2 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.
{"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}
Pub Date : 2025-04-14DOI: 10.1016/j.ijrefrig.2025.04.011
Xian Lyu, Zhili Sun, Wenfu Zhang, Dongxia Wu
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.
{"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}
Pub Date : 2025-04-12DOI: 10.1016/j.ijrefrig.2025.04.007
Ali Aminian
Natural refrigerants, low-GWP synthetic F-gas and mixtures in contact with lubricating oils in commercial air or heat-pumps were selected to study mutual solubility and miscibility in the temperature range from 248.15 K to 353.15 K. Due to restriction from F-gas regulation 2024 of the European commission (https://climate.ec.europa.eu), stress was put on the natural refrigerants and an industrial compressor oil. UNIFAC parameterization based on available experimental data was performed for systems comprising POE oils, HCFC, HFC, HFO, hydrocarbon, CO2, and ionic liquids. Also, it has been shown that the UNIFAC parameters developed in this study can readily be applied to the selective separation of refrigerant mixtures using Ionic Liquids. Molecular dynamics (MD) simulations of solvation free energy support the selectivity of ILs.
在248.15 K ~ 353.15 K的温度范围内，研究了天然制冷剂、低gwp合成f -气体以及与商业空气或热泵润滑油接触的混合物的相互溶解度和混相性。由于欧盟委员会的F-gas法规2024 （https://climate.ec.europa.eu）的限制，自然制冷剂和工业压缩机油受到了压力。根据现有实验数据，对POE油、HCFC、HFC、HFO、碳氢化合物、CO2和离子液体进行了UNIFAC参数化。此外，研究表明，本研究开发的UNIFAC参数可以很容易地应用于离子液体对制冷剂混合物的选择性分离。分子动力学（MD）模拟支持溶剂化自由能的选择性。
{"title":"Solubility and miscibility gap in refrigerants + lubricant, mixture of refrigerants + Ionic liquids, and hydrofluoroolefins + natural refrigerants systems: UNIFAC parameterization and solvation free energy calculations","authors":"Ali Aminian","doi":"10.1016/j.ijrefrig.2025.04.007","DOIUrl":"10.1016/j.ijrefrig.2025.04.007","url":null,"abstract":"<div><div>Natural refrigerants, low-GWP synthetic F-gas and mixtures in contact with lubricating oils in commercial air or heat-pumps were selected to study mutual solubility and miscibility in the temperature range from 248.15 K to 353.15 K. Due to restriction from F-gas regulation 2024 of the European commission (<span><span>https://climate.ec.europa.eu</span><svg><path></path></svg></span>), stress was put on the natural refrigerants and an industrial compressor oil. UNIFAC parameterization based on available experimental data was performed for systems comprising POE oils, HCFC, HFC, HFO, hydrocarbon, CO<sub>2</sub>, and ionic liquids. Also, it has been shown that the UNIFAC parameters developed in this study can readily be applied to the selective separation of refrigerant mixtures using Ionic Liquids. Molecular dynamics (MD) simulations of solvation free energy support the selectivity of ILs.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"175 ","pages":"Pages 373-388"},"PeriodicalIF":3.5,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143863810","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 : 2025-04-11DOI: 10.1016/j.ijrefrig.2025.03.048
Marcus Vinícius P. Carneiro , Jader R. Barbosa Jr.
The multi-jet spray cooling unit, integrated with a compact, linear, oil-free R-134a compressor introduced in previous work, is now experimentally evaluated with R-1234yf and R-600a as drop-in replacement alternatives. This unit combines the functions of the evaporator and the expansion device into a single device, allowing the subcooled refrigerant to expand through an array of oblique orifices and form a spray that directly impinges on the heated surface. The experimental analysis quantifies the cooling system thermodynamic performance, including compressor power and coefficient of performance, as well as steady-state heat transfer parameters such as heat transfer coefficient, surface temperature, and critical heat flux. The evaluation considers the influence of refrigerant charge, steady-state applied thermal load (cooling capacity), and refrigerant type. To ensure an unbiased comparison, the refrigerant charge is adjusted so that all refrigerants maintain the same evaporating temperature at the lowest thermal load of 25 W. Experimental tests are conducted across a wide range of evaporation temperatures (4.5 to 20.0 °C). The results indicate a trade-off between heat transfer performance and thermodynamic performance of the refrigeration system when selecting a refrigerant alternative. R-600a required the lowest refrigerant charge to achieve the reference evaporation temperature and exhibited the lowest refrigerant mass flow rate under all tested conditions. However, the heat transfer performance of R-600a is severely penalized compared to R-134a and R-1234yf, with approximately a 40% reduction in the maximum heat transfer coefficient. The maximum values of the heat transfer coefficient for R-134a, R-1234yf, and R-600a are 42.9, 43.4, and 25.8 kW/m K, respectively.
{"title":"Comparing the performances of R-134a, R-1234yf and R-600a in a compact spray refrigeration system for electronics cooling","authors":"Marcus Vinícius P. Carneiro , Jader R. Barbosa Jr.","doi":"10.1016/j.ijrefrig.2025.03.048","DOIUrl":"10.1016/j.ijrefrig.2025.03.048","url":null,"abstract":"<div><div>The multi-jet spray cooling unit, integrated with a compact, linear, oil-free R-134a compressor introduced in previous work, is now experimentally evaluated with R-1234yf and R-600a as drop-in replacement alternatives. This unit combines the functions of the evaporator and the expansion device into a single device, allowing the subcooled refrigerant to expand through an array of oblique orifices and form a spray that directly impinges on the heated surface. The experimental analysis quantifies the cooling system thermodynamic performance, including compressor power and coefficient of performance, as well as steady-state heat transfer parameters such as heat transfer coefficient, surface temperature, and critical heat flux. The evaluation considers the influence of refrigerant charge, steady-state applied thermal load (cooling capacity), and refrigerant type. To ensure an unbiased comparison, the refrigerant charge is adjusted so that all refrigerants maintain the same evaporating temperature at the lowest thermal load of 25 W. Experimental tests are conducted across a wide range of evaporation temperatures (4.5 to 20.0 °C). The results indicate a trade-off between heat transfer performance and thermodynamic performance of the refrigeration system when selecting a refrigerant alternative. R-600a required the lowest refrigerant charge to achieve the reference evaporation temperature and exhibited the lowest refrigerant mass flow rate under all tested conditions. However, the heat transfer performance of R-600a is severely penalized compared to R-134a and R-1234yf, with approximately a 40% reduction in the maximum heat transfer coefficient. The maximum values of the heat transfer coefficient for R-134a, R-1234yf, and R-600a are 42.9, 43.4, and 25.8 kW/m<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span> K, respectively.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"175 ","pages":"Pages 400-411"},"PeriodicalIF":3.5,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143874164","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 : 2025-04-10DOI: 10.1016/j.ijrefrig.2025.04.008
Yiqi Zhang , Baoqi Qiu , Zongwei Han
Fault detection and diagnosis (FDD) model for the cooling system is beneficial in elevating the reliability of data centers. Nevertheless, the model accuracy could be degraded by sensor measurement error, which may arise due to environmental interferences or inadequate maintenance practices. In the study, the impacts of sensor measurement error on the convolutional neuron network (CNN) based FDD model for the data center composite cooling system are assessed. Additionally, the coupled effects of sensor error and system control strategies on the FDD model are investigated. The results indicate that in vapor compression mode, a negative fixed sensor error of 1 K leads to an average 5 % greater decline in the CNN model accuracy compared to a positive error of the same magnitude. In contrast, the positive fixed error causes a 6.5 % higher decrease in heat pipe mode. Additionally, sensor errors have a negligible impact on model accuracy until exceeding the threshold, and the threshold of fixed error is 0.2 K in CNN model. Further, as a key control strategy involved parameters, the evaporating temperature error is critical to FDD model accuracy. In the fixed bias conditions, when the error magnitude is 1 K, the accuracy of FDD model decreases within the range of 24.8 % to 45.1 %.
{"title":"Effects of sensor measurement error on fault detection and diagnosis model for data center composite cooling system","authors":"Yiqi Zhang , Baoqi Qiu , Zongwei Han","doi":"10.1016/j.ijrefrig.2025.04.008","DOIUrl":"10.1016/j.ijrefrig.2025.04.008","url":null,"abstract":"<div><div>Fault detection and diagnosis (FDD) model for the cooling system is beneficial in elevating the reliability of data centers. Nevertheless, the model accuracy could be degraded by sensor measurement error, which may arise due to environmental interferences or inadequate maintenance practices. In the study, the impacts of sensor measurement error on the convolutional neuron network (CNN) based FDD model for the data center composite cooling system are assessed. Additionally, the coupled effects of sensor error and system control strategies on the FDD model are investigated. The results indicate that in vapor compression mode, a negative fixed sensor error of 1 K leads to an average 5 % greater decline in the CNN model accuracy compared to a positive error of the same magnitude. In contrast, the positive fixed error causes a 6.5 % higher decrease in heat pipe mode. Additionally, sensor errors have a negligible impact on model accuracy until exceeding the threshold, and the threshold of fixed error is 0.2 K in CNN model. Further, as a key control strategy involved parameters, the evaporating temperature error is critical to FDD model accuracy. In the fixed bias conditions, when the error magnitude is 1 K, the accuracy of FDD model decreases within the range of 24.8 % to 45.1 %.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"175 ","pages":"Pages 245-258"},"PeriodicalIF":3.5,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143845111","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 : 2025-04-10DOI: 10.1016/j.ijrefrig.2025.04.006
Hao Chen, Shanshan Li, Ziyang Wang
The inertance tube, as a crucial component of pulse tube refrigerators, directly determines the refrigeration efficiency through its phase-shifting capability. Traditional design methods for inertance tubes are often inefficient and struggle to identify the optimal dimensions due to the multiple influencing parameters and their complex coupling relationships. To address these issues, a comprehensive dataset of 641,986 data points, encompassing the phase-shifting characteristics of single-segment inertance tubes across a range of operational parameters and structural dimensions, was compiled to enhance precision. Principal Component Analysis was then employed to conduct an in-depth analysis of the correlations between the phase-shifting capability of the inertance tube and its operating and structural parameters. Additionally, Local Sensitivity Analysis was performed to evaluate the sensitivity of structural parameters at various value points. Combining the results of correlation and sensitivity analyses, an innovative design process and parameter selection strategy for inertance tube design was proposed, aiming to offer targeted guidance and improve the design efficiency.
{"title":"Parameters correlation and sensitivity analyses for single-segment inertance tubes in pulse tube cryocoolers: a comprehensive large-scale dataset investigation","authors":"Hao Chen, Shanshan Li, Ziyang Wang","doi":"10.1016/j.ijrefrig.2025.04.006","DOIUrl":"10.1016/j.ijrefrig.2025.04.006","url":null,"abstract":"<div><div>The inertance tube, as a crucial component of pulse tube refrigerators, directly determines the refrigeration efficiency through its phase-shifting capability. Traditional design methods for inertance tubes are often inefficient and struggle to identify the optimal dimensions due to the multiple influencing parameters and their complex coupling relationships. To address these issues, a comprehensive dataset of 641,986 data points, encompassing the phase-shifting characteristics of single-segment inertance tubes across a range of operational parameters and structural dimensions, was compiled to enhance precision. Principal Component Analysis was then employed to conduct an in-depth analysis of the correlations between the phase-shifting capability of the inertance tube and its operating and structural parameters. Additionally, Local Sensitivity Analysis was performed to evaluate the sensitivity of structural parameters at various value points. Combining the results of correlation and sensitivity analyses, an innovative design process and parameter selection strategy for inertance tube design was proposed, aiming to offer targeted guidance and improve the design efficiency.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"175 ","pages":"Pages 314-333"},"PeriodicalIF":3.5,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850363","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 : 2025-04-08DOI: 10.1016/j.ijrefrig.2025.04.005
Jiajia Song , Hequn Liu , Shenghan Jin , Chao Yuan , Jinqing Peng , Houpei Li
The maldistribution of refrigerant in header has a serious impact on the performance of the microchannel heat exchanger (MCHX). This study investigated using to obtain an improved flow distribution distributor in a MCHX. The tested inlet vapor quality covered from 0.2 to 0.6. Mass flow rate was 10 g/s. In the heat exchanger header, the two-phase distribution was quantified using a capacitance sensor for with and without distributor cases. The capacitive signals were comprehensively analyzed in the time, amplitude and frequency domains. Probability density function (PDF) and Fast Fourier Transform (FFT) of the capacitive signals were used to characterize flow patterns. The local vapor qualities calculated by the correlation was used to quantify two-phase distribution. This comprehensive analysis improved the accuracy of capacitive signal processing of two-phase flow characteristics. In the Fast Fourier Transform of capacitive signals, the more violent the two-phase flow, the greater fluctuation on the amplitude. The improvement of two-phase distribution by distributor and the two-phase flow characteristics at the distribution hole were discussed. At low inlet vapor quality, the distributor had a better effect on the maldistribution. At high inlet vapor quality, alternate vapor-liquid distribution would occur at the distribution hole. In this paper, the capacitive signals were comprehensively analyzed in the time, amplitude and frequency domains in the MCHX header for the first time. The two-phase flow state was specifically evaluated through the capacitive signal characteristics.
{"title":"A comprehensive analysis of capacitive signals of two-phase R134a characteristics in a microchannel heat exchanger header with and without a distributor","authors":"Jiajia Song , Hequn Liu , Shenghan Jin , Chao Yuan , Jinqing Peng , Houpei Li","doi":"10.1016/j.ijrefrig.2025.04.005","DOIUrl":"10.1016/j.ijrefrig.2025.04.005","url":null,"abstract":"<div><div>The maldistribution of refrigerant in header has a serious impact on the performance of the microchannel heat exchanger (MCHX). This study investigated using to obtain an improved flow distribution distributor in a MCHX. The tested inlet vapor quality covered from 0.2 to 0.6. Mass flow rate was 10 g/s. In the heat exchanger header, the two-phase distribution was quantified using a capacitance sensor for with and without distributor cases. The capacitive signals were comprehensively analyzed in the time, amplitude and frequency domains. Probability density function (PDF) and Fast Fourier Transform (FFT) of the capacitive signals were used to characterize flow patterns. The local vapor qualities calculated by the correlation was used to quantify two-phase distribution. This comprehensive analysis improved the accuracy of capacitive signal processing of two-phase flow characteristics. In the Fast Fourier Transform of capacitive signals, the more violent the two-phase flow, the greater fluctuation on the amplitude. The improvement of two-phase distribution by distributor and the two-phase flow characteristics at the distribution hole were discussed. At low inlet vapor quality<span><math><mrow><mo>(</mo><mrow><msub><mi>x</mi><mrow><mi>i</mi><mi>n</mi></mrow></msub><mo>≤</mo><mn>0.3</mn></mrow><mo>)</mo></mrow></math></span>, the distributor had a better effect on the maldistribution. At high inlet vapor quality<span><math><mrow><mo>(</mo><mrow><msub><mi>x</mi><mrow><mi>i</mi><mi>n</mi></mrow></msub><mo>=</mo><mn>0.6</mn></mrow><mo>)</mo></mrow></math></span>, alternate vapor-liquid distribution would occur at the distribution hole. In this paper, the capacitive signals were comprehensively analyzed in the time, amplitude and frequency domains in the MCHX header for the first time. The two-phase flow state was specifically evaluated through the capacitive signal characteristics.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"175 ","pages":"Pages 358-372"},"PeriodicalIF":3.5,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143860648","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 : 2025-04-08DOI: 10.1016/j.ijrefrig.2025.03.047
Yingjie Xu , Hengrui Zhang , Kai Wu , Huaqiang Jin , Mengjie Song , Xi Shen
The energy efficiency enhancement of refrigeration/heat pump systems is a crucial aspect of carbon emissions reduction. Accurately recognizing the frosting state of their evaporators in low-temperature environments to achieve precise defrosting is key to reducing system energy consumption. Intelligent recognition methods based on evaporator images hold promise for high recognition rates. However, in practical conditions, light intensity can severely reduce the identification accuracy of existing methods, necessitating improvements. Therefore, a highly adaptable new method based on texture features of evaporator surface images is presented in this study, where texture features is extracted by minimum-redundancy-maximum-relevance-enhanced gray level co-occurrence matrix, and classified by sparrow-algorithm-optimized extreme learning machine (GLCM-SELM), to overcome the impact of various light intensity. This method is validated using a dataset of 4125 evaporator images of three frosting states, which is experimentally collected under light intensity ranging from 5 to 2370 lx. Performance study and comparative analysis against existing methods are carried out. Results indicate that the new method achieves identification accuracy of approximately 95 % across different conditions, significantly outperforming existing methods by 6 % to 35 %. Its remarkably smaller standard deviation (0.05) demonstrates high stability. It also shows fast computing speed and low cost. Generally, it has good application potential.
{"title":"Comparative study on adaptable intelligent frost recognition method for air-source heat pump and cold chain based on image texture features under complex lighting conditions","authors":"Yingjie Xu , Hengrui Zhang , Kai Wu , Huaqiang Jin , Mengjie Song , Xi Shen","doi":"10.1016/j.ijrefrig.2025.03.047","DOIUrl":"10.1016/j.ijrefrig.2025.03.047","url":null,"abstract":"<div><div>The energy efficiency enhancement of refrigeration/heat pump systems is a crucial aspect of carbon emissions reduction. Accurately recognizing the frosting state of their evaporators in low-temperature environments to achieve precise defrosting is key to reducing system energy consumption. Intelligent recognition methods based on evaporator images hold promise for high recognition rates. However, in practical conditions, light intensity can severely reduce the identification accuracy of existing methods, necessitating improvements. Therefore, a highly adaptable new method based on texture features of evaporator surface images is presented in this study, where texture features is extracted by minimum-redundancy-maximum-relevance-enhanced gray level co-occurrence matrix, and classified by sparrow-algorithm-optimized extreme learning machine (GLCM-SELM), to overcome the impact of various light intensity. This method is validated using a dataset of 4125 evaporator images of three frosting states, which is experimentally collected under light intensity ranging from 5 to 2370 lx. Performance study and comparative analysis against existing methods are carried out. Results indicate that the new method achieves identification accuracy of approximately 95 % across different conditions, significantly outperforming existing methods by 6 % to 35 %. Its remarkably smaller standard deviation (0.05) demonstrates high stability. It also shows fast computing speed and low cost. Generally, it has good application potential.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"175 ","pages":"Pages 273-287"},"PeriodicalIF":3.5,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848014","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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