Pub Date : 2026-05-01Epub Date: 2026-02-02DOI: 10.1016/j.ijrefrig.2026.02.001
Ziyang Cheng , Xunfeng Li , Guoqing Shen , Min Xu , Xiulan Huai
Low-temperature-driven water-based adsorption refrigeration system is considered environmentally friendly alternatives with the potential to reduce carbon emissions and improve energy sustainability, especially when utilizing renewable or waste heat sources. However, the poor heat and mass transfer of conventionally-used particle-filled adsorption beds largely limits the performance of adsorption chillers. To address this challenge, this study proposes an innovative adsorption bed configuration that integrates topology-optimized fins with stepwise porosity distributions. A two-dimensional transient numerical model is developed to simulate the adsorption/desorption processes under realistic operating conditions. With a 10 % fin volume proportion, the topology-optimized structure increases SCP by 12.9 % and COP by 1.9 % relative to a straight-fin configuration, and by 194.7 % (SCP) and 8.7 % (COP) relative to a no-fin configuration. Further enhancement is achieved by combining stepwise porosity design, where the Type-4 configuration yields SCP and COP increases of 190.4 % and 10.8 % compared to the non-optimized structure. This study is among the first to explore the combined effect of topology optimization and stepwise porosity in adsorption bed design, demonstrating that the synergistic design significantly enhances thermal and mass transfer effectiveness, providing valuable guidance for the development of high-performance adsorption cooling systems.
{"title":"Cooling performances enhancement of adsorption bed with topology-optimized fins and stepwise porosity","authors":"Ziyang Cheng , Xunfeng Li , Guoqing Shen , Min Xu , Xiulan Huai","doi":"10.1016/j.ijrefrig.2026.02.001","DOIUrl":"10.1016/j.ijrefrig.2026.02.001","url":null,"abstract":"<div><div>Low-temperature-driven water-based adsorption refrigeration system is considered environmentally friendly alternatives with the potential to reduce carbon emissions and improve energy sustainability, especially when utilizing renewable or waste heat sources. However, the poor heat and mass transfer of conventionally-used particle-filled adsorption beds largely limits the performance of adsorption chillers. To address this challenge, this study proposes an innovative adsorption bed configuration that integrates topology-optimized fins with stepwise porosity distributions. A two-dimensional transient numerical model is developed to simulate the adsorption/desorption processes under realistic operating conditions. With a 10 % fin volume proportion, the topology-optimized structure increases SCP by 12.9 % and COP by 1.9 % relative to a straight-fin configuration, and by 194.7 % (SCP) and 8.7 % (COP) relative to a no-fin configuration. Further enhancement is achieved by combining stepwise porosity design, where the Type-4 configuration yields SCP and COP increases of 190.4 % and 10.8 % compared to the non-optimized structure. This study is among the first to explore the combined effect of topology optimization and stepwise porosity in adsorption bed design, demonstrating that the synergistic design significantly enhances thermal and mass transfer effectiveness, providing valuable guidance for the development of high-performance adsorption cooling systems.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"185 ","pages":"Pages 14-29"},"PeriodicalIF":3.8,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146147651","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 : 2026-05-01Epub Date: 2026-02-03DOI: 10.1016/j.ijrefrig.2026.02.002
Zhongyuan Wang , Yanxia Li , Zhenqiang Wang , Shengyuan Zhao , Fengjiao Yu , Zhongliang Liu
The initial frosting phenomenon is a discontinuous phase-change nucleation process. The temperature and surface conditions of cold surfaces exert a decisive influence on this phenomenon, particularly during the initial frosting stage. With the advancement of aerospace and energy transportation technologies, increasing attention has been paid to frosting phenomena and frost suppression methods at low temperatures (-100°C to -30°C) and ultra-low temperatures (-273°C to -100°C). For cold surfaces at different temperatures, surface roughness exerts differential effects on the frosting process due to variations in frosting modes. In this study, an experimental investigation was conducted on the initial frosting behavior of copper surfaces with varying roughness (Ra = 2.1∼57.8 μm) over a wide temperature range (-190°C to -30°C), and the influence of roughness on frost crystal coverage was quantitatively analyzed. It was found that under the cold surface conditions examined herein, three frosting modes were observed, which are cold surface sublimation frosting, air boundary layer condensation frosting, and air boundary layer sublimation frosting. Four types of frost crystal morphologies were identified, which are hexagonal prism (feather), branch (pine needle), cluster (shrub), and floc (grape).The effect of roughness on frost crystal coverage exhibits stage-specific characteristics: in the stage dominated by cold surface deposition, high roughness significantly promotes frost crystal growth; in the stage dominated by boundary layer deposition, low roughness inhibits water vapor mass transfer; under extremely low temperature conditions, the influence of roughness becomes random. Universal patterns across different roughness intervals are as follows: in the high roughness range (Ra = 57.8∼39.6 μm), cold surfaces at -30∼-50°C within the roughness range of Ra = 53.8∼57.8 μm exhibit the maximum frost crystal coverage. In the medium roughness range (Ra = 35.5∼20.3 μm), frost crystal coverage on most (>80%) cold surfaces at different temperatures is independent of roughness. In the low roughness range (Ra = 18.5∼2.1 μm), frost crystal coverage at -30°C decreases with decreasing surface roughness.
{"title":"The influence of cold surface roughness on the initial stage of frosting in a wide temperature range","authors":"Zhongyuan Wang , Yanxia Li , Zhenqiang Wang , Shengyuan Zhao , Fengjiao Yu , Zhongliang Liu","doi":"10.1016/j.ijrefrig.2026.02.002","DOIUrl":"10.1016/j.ijrefrig.2026.02.002","url":null,"abstract":"<div><div>The initial frosting phenomenon is a discontinuous phase-change nucleation process. The temperature and surface conditions of cold surfaces exert a decisive influence on this phenomenon, particularly during the initial frosting stage. With the advancement of aerospace and energy transportation technologies, increasing attention has been paid to frosting phenomena and frost suppression methods at low temperatures (-100°C to -30°C) and ultra-low temperatures (-273°C to -100°C). For cold surfaces at different temperatures, surface roughness exerts differential effects on the frosting process due to variations in frosting modes. In this study, an experimental investigation was conducted on the initial frosting behavior of copper surfaces with varying roughness (Ra = 2.1∼57.8 μm) over a wide temperature range (-190°C to -30°C), and the influence of roughness on frost crystal coverage was quantitatively analyzed. It was found that under the cold surface conditions examined herein, three frosting modes were observed, which are cold surface sublimation frosting, air boundary layer condensation frosting, and air boundary layer sublimation frosting. Four types of frost crystal morphologies were identified, which are hexagonal prism (feather), branch (pine needle), cluster (shrub), and floc (grape).The effect of roughness on frost crystal coverage exhibits stage-specific characteristics: in the stage dominated by cold surface deposition, high roughness significantly promotes frost crystal growth; in the stage dominated by boundary layer deposition, low roughness inhibits water vapor mass transfer; under extremely low temperature conditions, the influence of roughness becomes random. Universal patterns across different roughness intervals are as follows: in the high roughness range (Ra = 57.8∼39.6 μm), cold surfaces at -30∼-50°C within the roughness range of Ra = 53.8∼57.8 μm exhibit the maximum frost crystal coverage. In the medium roughness range (Ra = 35.5∼20.3 μm), frost crystal coverage on most (>80%) cold surfaces at different temperatures is independent of roughness. In the low roughness range (Ra = 18.5∼2.1 μm), frost crystal coverage at -30°C decreases with decreasing surface roughness.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"185 ","pages":"Pages 1-13"},"PeriodicalIF":3.8,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146147652","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 : 2026-04-01Epub Date: 2026-01-22DOI: 10.1016/j.ijrefrig.2026.01.030
Yuhui Chen , Ya Xu , Daming Sun , Zeming Wang , Qie Shen
To develop a cryogenic liquid pumping device suitable for low-flow-rate conditions, this paper presents a combined numerical and experimental investigation of a bubble pump using liquid nitrogen as the working fluid. The pump performance and internal hydrodynamic characteristics are systematically examined through varying submergence ratio and heating power. The results show that under the same heating power, as the submergence ratio increases, both the flow rate and lifting efficiency exhibit a trend of first increasing and then decreasing. At the same submergence ratio, an increase in heating power leads to a first rise followed by a fall in the flow rate, while the lifting efficiency decreases gradually. The maximum flow rate of 11.14 kg × h-1 occurs at a submersion ratio of 0.62 and a heating power of 35 W in the simulation. The maximum measured flow rate was 4.24 kg × h-1 at a submersion ratio of 0.473 and a heating power of 7 W. This research shows the prospect of cryogenic bubble pump in the field of low-flow-rate cryogenic liquid transfer, and provides the research foundation for the design and optimization of the cryogenic bubble pump.
为了研制一种适用于低流量条件下的低温抽液装置，本文对液氮作为工作流体的气泡泵进行了数值与实验相结合的研究。通过改变淹没比和加热功率，系统地考察了泵的性能和内部水动力特性。结果表明：在相同加热功率下，随着淹没比的增大，流量和举升效率均呈现先增大后减小的趋势；在相同淹没比下，加热功率的增加导致流量先上升后下降，举升效率逐渐降低。在淹没比为0.62、加热功率为35 W时，模拟的最大流量为11.14 kg × h-1。在浸没比0.473，加热功率7 W的条件下，最大测量流量为4.24 kg × h-1。本研究展望了低温气泡泵在低流量低温液体输送领域的发展前景，为低温气泡泵的设计与优化提供了研究基础。
{"title":"Performance study on a cryogenic bubble pump for low-flow-rate liquid nitrogen transfer","authors":"Yuhui Chen , Ya Xu , Daming Sun , Zeming Wang , Qie Shen","doi":"10.1016/j.ijrefrig.2026.01.030","DOIUrl":"10.1016/j.ijrefrig.2026.01.030","url":null,"abstract":"<div><div>To develop a cryogenic liquid pumping device suitable for low-flow-rate conditions, this paper presents a combined numerical and experimental investigation of a bubble pump using liquid nitrogen as the working fluid. The pump performance and internal hydrodynamic characteristics are systematically examined through varying submergence ratio and heating power. The results show that under the same heating power, as the submergence ratio increases, both the flow rate and lifting efficiency exhibit a trend of first increasing and then decreasing. At the same submergence ratio, an increase in heating power leads to a first rise followed by a fall in the flow rate, while the lifting efficiency decreases gradually. The maximum flow rate of 11.14 kg × h<sup>-1</sup> occurs at a submersion ratio of 0.62 and a heating power of 35 W in the simulation. The maximum measured flow rate was 4.24 kg × h<sup>-1</sup> at a submersion ratio of 0.473 and a heating power of 7 W. This research shows the prospect of cryogenic bubble pump in the field of low-flow-rate cryogenic liquid transfer, and provides the research foundation for the design and optimization of the cryogenic bubble pump.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"184 ","pages":"Pages 66-76"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076033","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}
Refrigerants are essential working fluids in refrigeration systems, and small amounts of lubricating oil are entrained during circulation. Therefore, investigating the thermodynamic properties of refrigerant/lubricant mixtures is critical. In this study, molecular models of isobutane (R600a) with three linear pentaerythritol esters (PECs), including pentaerythritol tetrabutyrate (PEC4), pentaerythritol tetrahexanoate (PEC6), and pentaerythritol tetraoctanoate (PEC8), were constructed, and thermodynamic properties of R600a/PECs mixtures were computed using the COSMO-RS model, with molecular geometries optimized via density functional theory. Results indicate that the electrostatic potential of R600a is uniformly distributed across its molecular surface, whereas negative electrostatic regions appear near oxygen atoms in PECs. The solubility of R600a in the three PECs follows the order PEC8 > PEC6 > PEC4. In mixtures of R600a with the three PECs, the activity coefficients, Henry’s constants, excess Gibbs free energies, and excess enthalpies follow the trend PEC4 > PEC6 > PEC8, whereas the excess entropy follows PEC8 > PEC6 > PEC4. Pressure–enthalpy–quality diagrams of R600a/PECs mixtures were further studied, and the critical vapor quality (), enthalpy ratio () and non-evaporated refrigerant quantity (NEQ) were analyzed. The , , and NEQ are influenced by the type of lubricant and its circulation fraction, lower refrigerant solubility and smaller lubricant circulation fractions lead to higher , closer to 1, and reduced NEQ. This study provides a comprehensive comparison of R600a/PECs mixtures, and the results provide guidance for optimizing refrigerant/lubricant formulations and offer a reliable theoretical basis for the selection and matching of refrigerants and lubricants.
{"title":"Study on the thermodynamic properties and evaporation performance of isobutane/linear pentaerythritol ester mixtures","authors":"Shuping Zhang, Zhao Yang, Hongxia He, Zhaoning Hou, Yanfeng Zhao, Lei Gao","doi":"10.1016/j.ijrefrig.2026.01.012","DOIUrl":"10.1016/j.ijrefrig.2026.01.012","url":null,"abstract":"<div><div>Refrigerants are essential working fluids in refrigeration systems, and small amounts of lubricating oil are entrained during circulation. Therefore, investigating the thermodynamic properties of refrigerant/lubricant mixtures is critical. In this study, molecular models of isobutane (R600a) with three linear pentaerythritol esters (PECs), including pentaerythritol tetrabutyrate (PEC4), pentaerythritol tetrahexanoate (PEC6), and pentaerythritol tetraoctanoate (PEC8), were constructed, and thermodynamic properties of R600a/PECs mixtures were computed using the COSMO-RS model, with molecular geometries optimized via density functional theory. Results indicate that the electrostatic potential of R600a is uniformly distributed across its molecular surface, whereas negative electrostatic regions appear near oxygen atoms in PECs. The solubility of R600a in the three PECs follows the order PEC8 > PEC6 > PEC4. In mixtures of R600a with the three PECs, the activity coefficients, Henry’s constants, excess Gibbs free energies, and excess enthalpies follow the trend PEC4 > PEC6 > PEC8, whereas the excess entropy follows PEC8 > PEC6 > PEC4. Pressure–enthalpy–quality diagrams of R600a/PECs mixtures were further studied, and the critical vapor quality (<span><math><msub><mi>X</mi><mrow><mi>c</mi><mi>r</mi></mrow></msub></math></span>), enthalpy ratio (<span><math><msub><mi>R</mi><mi>h</mi></msub></math></span>) and non-evaporated refrigerant quantity (NEQ) were analyzed. The <span><math><msub><mi>X</mi><mrow><mi>c</mi><mi>r</mi></mrow></msub></math></span>, <span><math><msub><mi>R</mi><mi>h</mi></msub></math></span>, and NEQ are influenced by the type of lubricant and its circulation fraction, lower refrigerant solubility and smaller lubricant circulation fractions lead to higher <span><math><msub><mi>X</mi><mrow><mi>c</mi><mi>r</mi></mrow></msub></math></span>, <span><math><msub><mi>R</mi><mi>h</mi></msub></math></span> closer to 1, and reduced NEQ. This study provides a comprehensive comparison of R600a/PECs mixtures, and the results provide guidance for optimizing refrigerant/lubricant formulations and offer a reliable theoretical basis for the selection and matching of refrigerants and lubricants.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"184 ","pages":"Pages 1-13"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037201","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}
This study experimentally evaluated the performance of an industrial-scale horizontal CO₂ plate freezer integrated into an existing CO₂ refrigeration system. The shared central CO2 system can provide cooling capacity of 100 kW at evaporation temperature between -30 °C and -50 °C. Apple juice cartons were employed as the primary test material acting as dummy loads; freezing times were also measured for real fish samples—including mackerel, herring, and salmon. Freezing trials with apple juice cartons showed that lowering the average evaporation temperature from –36.1 °C to –48.6 °C reduced the average freezing time by 35.3%. Although the Coefficient of Performance (COP) was lower at reduced evaporation temperatures, specific energy consumption remained largely unaffected because of shorter freezing times. Additionally, lower circulation rates were associated with longer freezing time and higher specific energy consumption. The experimental results also demonstrated the importance of uniform plate contact, packaging material and configuration, and optimized product void space for freezing efficiency. A dynamic numerical model was developed and validated against the experimental data, showing good agreement with observed temperature profiles and freezing times.
{"title":"Experimental analysis of freezing times for fish and dummy loads in a horizontal CO₂ plate freezer at -50 °C evaporation temperature","authors":"Shuai Ren , Patrick Hadamitzky , Armin Hafner , Kristina Norne Widell","doi":"10.1016/j.ijrefrig.2026.01.017","DOIUrl":"10.1016/j.ijrefrig.2026.01.017","url":null,"abstract":"<div><div>This study experimentally evaluated the performance of an industrial-scale horizontal CO₂ plate freezer integrated into an existing CO₂ refrigeration system. The shared central CO<sub>2</sub> system can provide cooling capacity of 100 kW at evaporation temperature between -30 °C and -50 °C. Apple juice cartons were employed as the primary test material acting as dummy loads; freezing times were also measured for real fish samples—including mackerel, herring, and salmon. Freezing trials with apple juice cartons showed that lowering the average evaporation temperature from –36.1 °C to –48.6 °C reduced the average freezing time by 35.3%. Although the Coefficient of Performance (COP) was lower at reduced evaporation temperatures, specific energy consumption remained largely unaffected because of shorter freezing times. Additionally, lower circulation rates were associated with longer freezing time and higher specific energy consumption. The experimental results also demonstrated the importance of uniform plate contact, packaging material and configuration, and optimized product void space for freezing efficiency. A dynamic numerical model was developed and validated against the experimental data, showing good agreement with observed temperature profiles and freezing times.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"184 ","pages":"Pages 14-29"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037202","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 : 2026-04-01Epub Date: 2026-01-22DOI: 10.1016/j.ijrefrig.2026.01.031
Hongwei Song , Yajin Zhang , Hong Yang , Ru Liu , Tao Yin , Liu Shi , Juan You
This study was conducted to elucidate the effect of NaCl content on thermal characteristics and the quality of eels under different freezing conditions with an aim to mitigate ice crystal damage, quality degradation, and energy inefficiency in frozen swamp eel meat. The results demonstrated that specific heat capacity and enthalpy of salted samples were lowered, while nonfreezing water content was increased compared with unsalted samples. Compared with unsalted samples, under 5 % NaCl salting condition, the electricity consumption of air freezing was lowered by 32.10 % at −40 °C, and the consumption of liquid nitrogen was lowered by 25.7 % at −90 °C LNSF (liquid nitrogen spray freezing). Moreover, the eel meat with 3 % NaCl salting and LNSF at −90 °C exhibited finer and more uniform ice crystal formation. This microstructural improvement resulted in a more complete retention of collagen, which led to a significant enhancement in hardness (p < 0.05) and an increase in myofibrillar protein solubility resulted in an increase in water holding capacity to 73.88 %. Consequently, the application of an optimal freezing temperature (−90 °C LNSF) with 3 % NaCl pretreatment significantly improves frozen eel meat quality and reduces energy consumption during the freezing process.
{"title":"Insights into frozen quality preservation and energy conservation of salted swamp eel (Monopterus albus) fillets","authors":"Hongwei Song , Yajin Zhang , Hong Yang , Ru Liu , Tao Yin , Liu Shi , Juan You","doi":"10.1016/j.ijrefrig.2026.01.031","DOIUrl":"10.1016/j.ijrefrig.2026.01.031","url":null,"abstract":"<div><div>This study was conducted to elucidate the effect of NaCl content on thermal characteristics and the quality of eels under different freezing conditions with an aim to mitigate ice crystal damage, quality degradation, and energy inefficiency in frozen swamp eel meat. The results demonstrated that specific heat capacity and enthalpy of salted samples were lowered, while nonfreezing water content was increased compared with unsalted samples. Compared with unsalted samples, under 5 % NaCl salting condition, the electricity consumption of air freezing was lowered by 32.10 % at −40 °C, and the consumption of liquid nitrogen was lowered by 25.7 % at −90 °C LNSF (liquid nitrogen spray freezing). Moreover, the eel meat with 3 % NaCl salting and LNSF at −90 °C exhibited finer and more uniform ice crystal formation. This microstructural improvement resulted in a more complete retention of collagen, which led to a significant enhancement in hardness (<em>p</em> < 0.05) and an increase in myofibrillar protein solubility resulted in an increase in water holding capacity to 73.88 %. Consequently, the application of an optimal freezing temperature (−90 °C LNSF) with 3 % NaCl pretreatment significantly improves frozen eel meat quality and reduces energy consumption during the freezing process.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"184 ","pages":"Pages 30-41"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075914","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 : 2026-04-01Epub Date: 2026-01-27DOI: 10.1016/j.ijrefrig.2026.01.034
Faheem Ejaz , Shahzada Zaman Shuja , Naef A.A. Qasem , Syed M. Zubair
Offset strip fins are widely used in aerospace, automotive, cryogenic, air cooling, and industrial applications. However, their performance under wet surface conditions, especially for flat tube heat exchangers, remains underexplored. This study investigates the thermal-hydraulic performance of fifteen newly developed offset strip fin geometries with flat tubes under humid conditions. Simulations were conducted using a multiphase modeling approach in ANSYS Fluent, employing the volume of fluid (VOF) method with species transport. An automated workflow was developed using FreeCAD and Scheme scripting to streamline geometry generation, simulation setup, and data extraction. Performance was evaluated using classical metrics, such as the Colburn heat transfer factor (j) and Fanning friction factor (f), as well as robust indicators, including surface goodness factor, compactness-weighted criteria, and fixed pumping power per unit area requirements. Results showed that wet surface operation yielded up to 12% enhancement in heat transfer and 10% increase in friction. Configurations GS5, GS6, GS9, and GS12 showed superior thermal performance with relatively lower pressure penalties. Compared to published designs, GS9 and GS12 achieved up to 45% higher heat transfer. Furthermore, optimized designs were also proposed based on minimizing friction losses and maximizing heat transfer performance. Despite the straightforwardness of the correlations, artificial neural network models showed better predictions for “f ” and “j” with 97.6% and 96.7% accuracy, respectively.
{"title":"A comprehensive thermal-hydraulic assessment of offset strip fin flat-tube heat exchangers under humid conditions: Numerical and artificial neural network approaches","authors":"Faheem Ejaz , Shahzada Zaman Shuja , Naef A.A. Qasem , Syed M. Zubair","doi":"10.1016/j.ijrefrig.2026.01.034","DOIUrl":"10.1016/j.ijrefrig.2026.01.034","url":null,"abstract":"<div><div>Offset strip fins are widely used in aerospace, automotive, cryogenic, air cooling, and industrial applications. However, their performance under wet surface conditions, especially for flat tube heat exchangers, remains underexplored. This study investigates the thermal-hydraulic performance of fifteen newly developed offset strip fin geometries with flat tubes under humid conditions. Simulations were conducted using a multiphase modeling approach in ANSYS Fluent, employing the volume of fluid (VOF) method with species transport. An automated workflow was developed using FreeCAD and Scheme scripting to streamline geometry generation, simulation setup, and data extraction. Performance was evaluated using classical metrics, such as the Colburn heat transfer factor (<em>j</em>) and Fanning friction factor (<em>f</em>), as well as robust indicators, including surface goodness factor, compactness-weighted criteria, and fixed pumping power per unit area requirements. Results showed that wet surface operation yielded up to 12% enhancement in heat transfer and 10% increase in friction. Configurations GS<sub>5</sub>, GS<sub>6</sub>, GS<sub>9</sub>, and GS<sub>12</sub> showed superior thermal performance with relatively lower pressure penalties. Compared to published designs, GS<sub>9</sub> and GS<sub>12</sub> achieved up to 45% higher heat transfer. Furthermore, optimized designs were also proposed based on minimizing friction losses and maximizing heat transfer performance. Despite the straightforwardness of the correlations, artificial neural network models showed better predictions for “<em>f</em> ” and “<em>j</em>” with 97.6% and 96.7% accuracy, respectively.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"184 ","pages":"Pages 168-180"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191110","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}
The ENOUGH tool is a web-based simulation platform designed to help reducing the carbon footprint of food supply chains while improving product quality. The tool dynamically calculates time-temperature profiles, energy consumption, and greenhouse gas (GHG) emissions across the supply chain. It models key elements such as refrigeration (considering COP, TEWI), transportation (using tonne-kilometre and the GLEC framework), and packaging. It also integrates food quality kinetic models. A significant advantage over traditional life cycle assessments (LCA) is its granular approach and unique incorporation of product quality alongside environmental impacts.
Two examples of case studies demonstrate its utility, highlighting transportation as a major GHG contributor. The first example is based on two scenarios for apple supply chains, with a long-distance imported product that has a higher environmental impact than local varieties. In the second example that focuses on yogurt's last-mile delivery, it is shown that local stores or e-commerce often result in lower emissions due to reduced consumer travel or more efficient logistics.
The objective of the ENOUGH tool is to empower users to identify and implement comprehensive strategies that make food supply systems more sustainable and environmentally friendly.
{"title":"Enough tool: decarbonizing food supply chains while improving product quality","authors":"Denis Leducq , Hong Minh Hoang , Pieter Verboven , Graciela Alvarez","doi":"10.1016/j.ijrefrig.2026.01.005","DOIUrl":"10.1016/j.ijrefrig.2026.01.005","url":null,"abstract":"<div><div>The ENOUGH tool is a web-based simulation platform designed to help reducing the carbon footprint of food supply chains while improving product quality. The tool dynamically calculates time-temperature profiles, energy consumption, and greenhouse gas (GHG) emissions across the supply chain. It models key elements such as refrigeration (considering COP, TEWI), transportation (using tonne-kilometre and the GLEC framework), and packaging. It also integrates food quality kinetic models. A significant advantage over traditional life cycle assessments (LCA) is its granular approach and unique incorporation of product quality alongside environmental impacts.</div><div>Two examples of case studies demonstrate its utility, highlighting transportation as a major GHG contributor. The first example is based on two scenarios for apple supply chains, with a long-distance imported product that has a higher environmental impact than local varieties. In the second example that focuses on yogurt's last-mile delivery, it is shown that local stores or e-commerce often result in lower emissions due to reduced consumer travel or more efficient logistics.</div><div>The objective of the ENOUGH tool is to empower users to identify and implement comprehensive strategies that make food supply systems more sustainable and environmentally friendly.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"184 ","pages":"Pages 159-167"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146191111","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 : 2026-04-01Epub Date: 2026-01-20DOI: 10.1016/j.ijrefrig.2026.01.025
Pengcheng Qu , Zhichao Chen , Ziqi Wei , Yuanting Zhang , Jinjian Chu , Baoyu Yang , Xi Chen , Shaoshuai Liu
Gas contamination significantly limits the reliability of Helium Joule-Thomson Cryocoolers (JTC) in long-life space missions. Distinct from previous studies that focus on contamination during cooldown, this research investigates the dynamic clogging mechanism caused by gradual contaminant accumulation during continuous operation. A method of multiple quantitative additions of air is employed to explore the impact on operating characteristics. Experimental results reveal that air contaminants primarily desublimate into solid frost layers in the second-stage counter-flow heat exchanger (CFHX 2) within the temperature range of 65–15 K, eventually leading to clogging. This process exhibits four novel stages: nucleation-growth, steady-growth, collapse-reconstruction, and clogging. To elucidate the mechanism, a gas contaminant desublimation model is established. Simulation results confirm that nitrogen deposits heavily around 35–45 K within CFHX 2, serving as the primary source of flow resistance. Furthermore, the study uncovers that the synergistic deposition of multi-component contaminants may lead to the frost layer instability observed during the collapse-reconstruction stage. This work clarifies the dynamic clogging mechanism of air contamination, providing a quantitative basis for reliability assessment and suppression strategies for Helium JTCs.
{"title":"Study on the effect of air contamination in helium on the reliability of a Helium Joule-Thomson cryocooler","authors":"Pengcheng Qu , Zhichao Chen , Ziqi Wei , Yuanting Zhang , Jinjian Chu , Baoyu Yang , Xi Chen , Shaoshuai Liu","doi":"10.1016/j.ijrefrig.2026.01.025","DOIUrl":"10.1016/j.ijrefrig.2026.01.025","url":null,"abstract":"<div><div>Gas contamination significantly limits the reliability of Helium Joule-Thomson Cryocoolers (JTC) in long-life space missions. Distinct from previous studies that focus on contamination during cooldown, this research investigates the dynamic clogging mechanism caused by gradual contaminant accumulation during continuous operation. A method of multiple quantitative additions of air is employed to explore the impact on operating characteristics. Experimental results reveal that air contaminants primarily desublimate into solid frost layers in the second-stage counter-flow heat exchanger (CFHX 2) within the temperature range of 65–15 K, eventually leading to clogging. This process exhibits four novel stages: nucleation-growth, steady-growth, collapse-reconstruction, and clogging. To elucidate the mechanism, a gas contaminant desublimation model is established. Simulation results confirm that nitrogen deposits heavily around 35–45 K within CFHX 2, serving as the primary source of flow resistance. Furthermore, the study uncovers that the synergistic deposition of multi-component contaminants may lead to the frost layer instability observed during the collapse-reconstruction stage. This work clarifies the dynamic clogging mechanism of air contamination, providing a quantitative basis for reliability assessment and suppression strategies for Helium JTCs.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"184 ","pages":"Pages 104-113"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075915","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 : 2026-04-01Epub Date: 2026-01-25DOI: 10.1016/j.ijrefrig.2026.01.033
Jakub Chrobak , Graciela Álvarez , Michał Palacz , Jacek Smołka , Fatou-Toutie Ndoye
This study examines how the pre-freezing method affects the microstructure of freeze-dried food products. Cylindrical potato and apple samples were pre-frozen either by convective freezing or vacuum freezing and then identically freeze-dried. High-resolution X-ray micro-computed tomography with a voxel size of 6.17 µm quantified air volume fraction, pore diameter distributions, sphericity and tortuosity. Segmentation consisted of image smoothing, artefacts removal, image binarisation, object separation and labelling. A one-way analysis of variance () assessed the effect of pre-freezing within each product. Apples exhibited higher air fractions than potatoes (0.78 versus 0.75), and also a greater share of mid-range pores but lower sphericity (0.11 versus 0.28), consistent with the intrinsic tissue architecture differences. Between convective and vacuum freezing of the same samples, the group means did not differ significantly for any property, except sphericity for apples. Thus, under the conditions studied, product type dominated pore formation, while the pre-freezing method induced only minor, non-significant changes. Nevertheless, the trends observed under vacuum freezing imply prospective advantages for mass-transfer efficiency and rehydration behaviour that merit further exploration. These findings support a view in which freezing sets the pore network later conserved by sublimation.
{"title":"Impact of the freezing method on the microstructure of the freeze-dried food products","authors":"Jakub Chrobak , Graciela Álvarez , Michał Palacz , Jacek Smołka , Fatou-Toutie Ndoye","doi":"10.1016/j.ijrefrig.2026.01.033","DOIUrl":"10.1016/j.ijrefrig.2026.01.033","url":null,"abstract":"<div><div>This study examines how the pre-freezing method affects the microstructure of freeze-dried food products. Cylindrical potato and apple samples were pre-frozen either by convective freezing or vacuum freezing and then identically freeze-dried. High-resolution X-ray micro-computed tomography with a voxel size of 6.17 µm quantified air volume fraction, pore diameter distributions, sphericity and tortuosity. Segmentation consisted of image smoothing, artefacts removal, image binarisation, object separation and labelling. A one-way analysis of variance (<span><math><mrow><mi>α</mi><mo>=</mo><mn>0.05</mn></mrow></math></span>) assessed the effect of pre-freezing within each product. Apples exhibited higher air fractions than potatoes (0.78 versus 0.75), and also a greater share of mid-range pores but lower sphericity (0.11 versus 0.28), consistent with the intrinsic tissue architecture differences. Between convective and vacuum freezing of the same samples, the group means did not differ significantly for any property, except sphericity for apples. Thus, under the conditions studied, product type dominated pore formation, while the pre-freezing method induced only minor, non-significant changes. Nevertheless, the trends observed under vacuum freezing imply prospective advantages for mass-transfer efficiency and rehydration behaviour that merit further exploration. These findings support a view in which freezing sets the pore network later conserved by sublimation.</div></div>","PeriodicalId":14274,"journal":{"name":"International Journal of Refrigeration-revue Internationale Du Froid","volume":"184 ","pages":"Pages 148-158"},"PeriodicalIF":3.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190607","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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