Pub Date : 2025-12-15DOI: 10.1016/j.ijheatmasstransfer.2025.128243
Lihao Wan , Chao Yang , Jinliang Yuan , Liusheng Xiao
Balancing performance and durability in low-temperature proton exchange membrane fuel cells (LT-PEMFCs) is often overlooked, while durability is related to the uniformity of performance distributions. To address this issue, the LT-PEMFC model with a serpentine flow field is developed by considering the combined effects of porosity gradients and compression in gas diffusion layers (GDLs). The work reveals how the combined effects interact and affect the permeability and electrical conductivity of GDLs, and mass, temperature and current density uniformity of PEMFCs. The results show that, without compression, porosity gradients significantly improve the performance and uniformity by 5.0 % and 9.9 %, respectively. Under compression, porosity gradients improve fuel cell performance by 2.2 %, and enhance the uniformity of oxygen concentration, current density and temperature by 4.7 %, 2.6 % and 11.7 %, respectively. Significantly, porosity gradients not only promote more uniform electrochemical reactions but also alleviate the non-uniformity caused by compression. Finally, stepwise porosity gradient is proved to be the best design compared to uniform, linear and sinusoidal porosity gradients, satisfying slightly better performance and significantly higher durability simultaneously. This work provides theoretical insights for optimizing GDL structures to achieve a balance between fuel cell performance and durability.
{"title":"Balancing performance and uniformity of LT-PEMFCs by considering GDL porosity gradients and compression","authors":"Lihao Wan , Chao Yang , Jinliang Yuan , Liusheng Xiao","doi":"10.1016/j.ijheatmasstransfer.2025.128243","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128243","url":null,"abstract":"<div><div>Balancing performance and durability in low-temperature proton exchange membrane fuel cells (LT-PEMFCs) is often overlooked, while durability is related to the uniformity of performance distributions. To address this issue, the LT-PEMFC model with a serpentine flow field is developed by considering the combined effects of porosity gradients and compression in gas diffusion layers (GDLs). The work reveals how the combined effects interact and affect the permeability and electrical conductivity of GDLs, and mass, temperature and current density uniformity of PEMFCs. The results show that, without compression, porosity gradients significantly improve the performance and uniformity by 5.0 % and 9.9 %, respectively. Under compression, porosity gradients improve fuel cell performance by 2.2 %, and enhance the uniformity of oxygen concentration, current density and temperature by 4.7 %, 2.6 % and 11.7 %, respectively. Significantly, porosity gradients not only promote more uniform electrochemical reactions but also alleviate the non-uniformity caused by compression. Finally, stepwise porosity gradient is proved to be the best design compared to uniform, linear and sinusoidal porosity gradients, satisfying slightly better performance and significantly higher durability simultaneously. This work provides theoretical insights for optimizing GDL structures to achieve a balance between fuel cell performance and durability.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"257 ","pages":"Article 128243"},"PeriodicalIF":5.8,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-15DOI: 10.1016/j.ijheatmasstransfer.2025.128246
Junjie Chen , Qianglong Zhou , Yufeng Gan , Longfei Ma , Zhen Liu , Huawei Wu
As the core heat transfer component of the thermal management system for power batteries, the optimal design of the flow channel configuration of the liquid cooling plate plays a crucial role in mitigating the risk of localized thermal runaway. This study proposes a novel bio-inspired wing-vein liquid cooling plate (WCP) structure design, which integrates the structural advantages of parallel channel liquid cooling plates (PCP) and fishbone-type channel liquid cooling plates (FCP) with the special structure of wing veins. The thermal dissipation characteristics of the liquid cooling plate were numerically analyzed using a thermal-fluid-solid coupled model. Additionally, a battery liquid cooling experimental test platform with an adjustable discharge rate was designed to validate the accuracy of battery heat generation models and numerical methods. Finally, a multi-objective optimization analysis was conducted on key parameters of the bio-inspired wing-vein channel, including the main channel angle, secondary channel angle, flow channel height, and inlet flow velocity, employing orthogonal experiments and the NSGA-II genetic algorithm. Research findings indicate that the flow channel height and inlet flow velocity of the new bio-inspired wing-vein liquid cooling plate exert a greater influence on battery temperature uniformity and system pressure drop than the main and secondary channel angle. The optimal structural parameters were determined to be α=79° (main channel angle), β=74° (secondary channel angle), d = 3.4 mm (channel height), and v = 1.4m/s (inlet flow velocity). Compared to the PCP and FCP designs, the battery module with the WCP structure exhibited a reduction in average temperature by 2.09 °C and 1.13 °C, a decrease in maximum temperature difference by 1.2 °C and 1.03 °C, and a reduction in pressure drop by 54 Pa and 41 Pa, respectively. The findings indicate that the suggested design successfully reduces heat buildup in the center of the battery, serving as a useful guide for the creation of liquid cooling plates that offer improved thermal efficiency and better temperature distribution.
{"title":"Bio-inspired wing-vein design for liquid cooling plates: Optimal configuration and thermal performance evaluation","authors":"Junjie Chen , Qianglong Zhou , Yufeng Gan , Longfei Ma , Zhen Liu , Huawei Wu","doi":"10.1016/j.ijheatmasstransfer.2025.128246","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128246","url":null,"abstract":"<div><div>As the core heat transfer component of the thermal management system for power batteries, the optimal design of the flow channel configuration of the liquid cooling plate plays a crucial role in mitigating the risk of localized thermal runaway. This study proposes a novel bio-inspired wing-vein liquid cooling plate (WCP) structure design, which integrates the structural advantages of parallel channel liquid cooling plates (PCP) and fishbone-type channel liquid cooling plates (FCP) with the special structure of wing veins. The thermal dissipation characteristics of the liquid cooling plate were numerically analyzed using a thermal-fluid-solid coupled model. Additionally, a battery liquid cooling experimental test platform with an adjustable discharge rate was designed to validate the accuracy of battery heat generation models and numerical methods. Finally, a multi-objective optimization analysis was conducted on key parameters of the bio-inspired wing-vein channel, including the main channel angle, secondary channel angle, flow channel height, and inlet flow velocity, employing orthogonal experiments and the NSGA-II genetic algorithm. Research findings indicate that the flow channel height and inlet flow velocity of the new bio-inspired wing-vein liquid cooling plate exert a greater influence on battery temperature uniformity and system pressure drop than the main and secondary channel angle. The optimal structural parameters were determined to be <em>α</em>=79° (main channel angle), <em>β</em>=74° (secondary channel angle), <em>d</em> = 3.4 mm (channel height), and <em>v</em> = 1.4m/s (inlet flow velocity). Compared to the PCP and FCP designs, the battery module with the WCP structure exhibited a reduction in average temperature by 2.09 °C and 1.13 °C, a decrease in maximum temperature difference by 1.2 °C and 1.03 °C, and a reduction in pressure drop by 54 Pa and 41 Pa, respectively. The findings indicate that the suggested design successfully reduces heat buildup in the center of the battery, serving as a useful guide for the creation of liquid cooling plates that offer improved thermal efficiency and better temperature distribution.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"257 ","pages":"Article 128246"},"PeriodicalIF":5.8,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-15DOI: 10.1016/j.ijheatmasstransfer.2025.128244
In Seop Lim , Sumin Lee , Byeonghyun Kang , Yoon-Young Choi , Hwanyeong Oh , Young-Jun Sohn , Minjin Kim
Liquid water in the cathode electrode modifies pore size and hinders oxygen diffusion. While previous studies have qualitatively described the adverse impact of liquid water, few studies have quantitatively analyzed the effects of liquid water on pore size and oxygen transport characteristics. In this study, a PEMFC numerical model that integrates the electrochemical performance, liquid water saturation, pore diameter, and oxygen transport characteristics in four electrode domains: gas diffusion backing layer (GDBL), microporous layer (MPL), catalyst layer (CL, secondary pore of catalyst layer), and Pt/C agglomerate (primary pore of catalyst layer). The effects of the operating conditions (current load, supplied air relative humidity) and the location in reaction area on liquid water saturation, resulting pore diameter, and oxygen transport characteristics are quantitatively assessed. Representatively, with current load increasing from 0.32 A/cm2 to 1.28 A/cm2, the average liquid water saturation in CL increases by 57.8 %, leading to 9.8 % pore diameter decrement. Although CL has the highest liquid water saturation, Pt/C agglomerate shows the lowest overall effective diffusion coefficient of 2.0 × 10−7 m2/s. MPL has the greatest decrement of oxygen concentration considering the domain thickness. The results show the variables’ effects on oxygen transport-related characteristics, domain-specific quantitative analysis, and determinants of oxygen transport-related characteristics. In particular, domain-specific quantitative analysis suggests domain-specific improvement needed, such as water management in CL, intrinsic oxygen transport characteristic in Pt/C agglomerate, and thickness of MPL. This study offers a robust and valuable modeling framework to assist design and optimization of PEMFC cathode electrode.
{"title":"Quantitative analysis of liquid water-induced pore size and oxygen transport variations with integrated mass transport model of PEMFC multilayer electrodes coupled with electrochemical reactions","authors":"In Seop Lim , Sumin Lee , Byeonghyun Kang , Yoon-Young Choi , Hwanyeong Oh , Young-Jun Sohn , Minjin Kim","doi":"10.1016/j.ijheatmasstransfer.2025.128244","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128244","url":null,"abstract":"<div><div>Liquid water in the cathode electrode modifies pore size and hinders oxygen diffusion. While previous studies have qualitatively described the adverse impact of liquid water, few studies have quantitatively analyzed the effects of liquid water on pore size and oxygen transport characteristics. In this study, a PEMFC numerical model that integrates the electrochemical performance, liquid water saturation, pore diameter, and oxygen transport characteristics in four electrode domains: gas diffusion backing layer (GDBL), microporous layer (MPL), catalyst layer (CL, secondary pore of catalyst layer), and Pt/C agglomerate (primary pore of catalyst layer). The effects of the operating conditions (current load, supplied air relative humidity) and the location in reaction area on liquid water saturation, resulting pore diameter, and oxygen transport characteristics are quantitatively assessed. Representatively, with current load increasing from 0.32 A/cm<sup>2</sup> to 1.28 A/cm<sup>2</sup>, the average liquid water saturation in CL increases by 57.8 %, leading to 9.8 % pore diameter decrement. Although CL has the highest liquid water saturation, Pt/C agglomerate shows the lowest overall effective diffusion coefficient of 2.0 × 10<sup>−7</sup> m<sup>2</sup>/s. MPL has the greatest decrement of oxygen concentration considering the domain thickness. The results show the variables’ effects on oxygen transport-related characteristics, domain-specific quantitative analysis, and determinants of oxygen transport-related characteristics. In particular, domain-specific quantitative analysis suggests domain-specific improvement needed, such as water management in CL, intrinsic oxygen transport characteristic in Pt/C agglomerate, and thickness of MPL. This study offers a robust and valuable modeling framework to assist design and optimization of PEMFC cathode electrode.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"257 ","pages":"Article 128244"},"PeriodicalIF":5.8,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-14DOI: 10.1016/j.ijheatmasstransfer.2025.128240
Mahmut D. Mat, Dietmar Kuhn, Abdalla Batta
Flashing two-phase flows under sub-atmospheric outlet conditions in a converging–diverging nozzle are investigated using the Homogeneous Relaxation Model (HRM) within a two-phase mixture flow framework. The main objectives of this study are to conduct an in-depth investigation of low-temperature, low-pressure flash evaporation, which is essential in flash-based wastewater purification and power generation systems that utilize low-grade waste heat as an energy source, and to support the improvement of a proof-of-concept experimental setup currently being established in our laboratory through the findings of this study.
The numerical results demonstrate that the mathematical model accurately reproduces pressure and void fraction distributions reported in the literature. It also captures key flashing features—including pressure undershoots, vapor generation delays, and pressure recovery—through the relaxation-time formulation. The results indicate that flashing flow in a converging–diverging nozzle is characterized by a sharp pressure drop near the throat, followed by rapid vapor generation and partial pressure recovery in the diverging section. This behaviour is primarily governed by nozzle geometry and the large disparity in specific volumes between the liquid and vapor phases. Vapor generation increases markedly at higher inlet pressures and temperatures, driven by the greater availability of superheat energy. The simulations further reveal that the mass flow rate is highly sensitive to inlet conditions: elevated inlet temperatures intensify vapor generation and consequently reduce mass flow rate, whereas achieving both high vapor production and high mass flow rates requires sufficiently high inlet pressures. The model also predicts shorter flash-delay distances at higher pressures, indicating an earlier onset of phase change, while longer delays occur at elevated temperatures due to increased metastability. Additionally, pressure undershoots become more pronounced with higher inlet temperatures, whereas their dependence on inlet pressure is negligible. It is found that, under fixed inlet conditions, lower sub-atmospheric back pressures enhance steam generation and promote pressure recovery after the nozzle throat, while simultaneously reducing the mass flow rate and the magnitude of pressure undershoots.
{"title":"Application of the homogeneous relaxation model for flash boiling under sub-atmospheric pressures","authors":"Mahmut D. Mat, Dietmar Kuhn, Abdalla Batta","doi":"10.1016/j.ijheatmasstransfer.2025.128240","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128240","url":null,"abstract":"<div><div>Flashing two-phase flows under sub-atmospheric outlet conditions in a converging–diverging nozzle are investigated using the Homogeneous Relaxation Model (HRM) within a two-phase mixture flow framework. The main objectives of this study are to conduct an in-depth investigation of low-temperature, low-pressure flash evaporation, which is essential in flash-based wastewater purification and power generation systems that utilize low-grade waste heat as an energy source, and to support the improvement of a proof-of-concept experimental setup currently being established in our laboratory through the findings of this study.</div><div>The numerical results demonstrate that the mathematical model accurately reproduces pressure and void fraction distributions reported in the literature. It also captures key flashing features—including pressure undershoots, vapor generation delays, and pressure recovery—through the relaxation-time formulation. The results indicate that flashing flow in a converging–diverging nozzle is characterized by a sharp pressure drop near the throat, followed by rapid vapor generation and partial pressure recovery in the diverging section. This behaviour is primarily governed by nozzle geometry and the large disparity in specific volumes between the liquid and vapor phases. Vapor generation increases markedly at higher inlet pressures and temperatures, driven by the greater availability of superheat energy. The simulations further reveal that the mass flow rate is highly sensitive to inlet conditions: elevated inlet temperatures intensify vapor generation and consequently reduce mass flow rate, whereas achieving both high vapor production and high mass flow rates requires sufficiently high inlet pressures. The model also predicts shorter flash-delay distances at higher pressures, indicating an earlier onset of phase change, while longer delays occur at elevated temperatures due to increased metastability. Additionally, pressure undershoots become more pronounced with higher inlet temperatures, whereas their dependence on inlet pressure is negligible. It is found that, under fixed inlet conditions, lower sub-atmospheric back pressures enhance steam generation and promote pressure recovery after the nozzle throat, while simultaneously reducing the mass flow rate and the magnitude of pressure undershoots.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"257 ","pages":"Article 128240"},"PeriodicalIF":5.8,"publicationDate":"2025-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-13DOI: 10.1016/j.ijheatmasstransfer.2025.128238
Sathyasree Nirmala , Sutheesh P M , Rohinikumar Bandaru
Electric vehicles (EVs) has demand for safe and efficient battery thermal management systems (BTMSs) to operate under diverse environmental conditions. Phase change materials (PCMs) offers heat absorption during phase transition, but their low thermal conductivity limits rapid heat dissipation, particularly under high discharge rates. Experimental investigations are carried out on bioinspired BTMS that integrates cylindrical lithium-ion cells with Fibonacci spiral aluminium fins in 1-tetradecanol PCM under 1C and 2C rates across ambient temperatures from 278.15 K to 305.15 K. Fibonacci finned system results in lower voltage degradation rate, minimizing internal resistance, suppressing capacity fade and extending discharge duration under 1C and 2C conditions. At 2C, finned system’s discharge duration improved by 13.4 % than unfinned system. Fibonacci fins provided optimized conductive pathways, enabling delayed onset of phase change and uniform melting. Finned system possesses lowest temperature rise of cell and highest duration for the discharge process and lowest instantaneous temperature during discharge than unfinned system for all the conditions considered. Temperature rise of cell is 9.1 K and 15.87 K for ambient temperature of 278.15 K in unfinned system at 1C and 2C rates, respectively and corresponding values are 5.33 K and 10.66 K in finned system. Average temperature rise for finned PCM 41.51 % lower than unfinned system at 1C discharge. Bioinspired geometry with latent heat storage offers new pathway for passive BTMS in next generation high power energy storage systems.
{"title":"Experimental investigations on thermal performance of lithium-ion cell with fibonacci finned PCM","authors":"Sathyasree Nirmala , Sutheesh P M , Rohinikumar Bandaru","doi":"10.1016/j.ijheatmasstransfer.2025.128238","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128238","url":null,"abstract":"<div><div>Electric vehicles (EVs) has demand for safe and efficient battery thermal management systems (BTMSs) to operate under diverse environmental conditions. Phase change materials (PCMs) offers heat absorption during phase transition, but their low thermal conductivity limits rapid heat dissipation, particularly under high discharge rates. Experimental investigations are carried out on bioinspired BTMS that integrates cylindrical lithium-ion cells with Fibonacci spiral aluminium fins in 1-tetradecanol PCM under 1C and 2C rates across ambient temperatures from 278.15 K to 305.15 K. Fibonacci finned system results in lower voltage degradation rate, minimizing internal resistance, suppressing capacity fade and extending discharge duration under 1C and 2C conditions. At 2C, finned system’s discharge duration improved by 13.4 % than unfinned system. Fibonacci fins provided optimized conductive pathways, enabling delayed onset of phase change and uniform melting. Finned system possesses lowest temperature rise of cell and highest duration for the discharge process and lowest instantaneous temperature during discharge than unfinned system for all the conditions considered. Temperature rise of cell is 9.1 K and 15.87 K for ambient temperature of 278.15 K in unfinned system at 1C and 2C rates, respectively and corresponding values are 5.33 K and 10.66 K in finned system. Average temperature rise for finned PCM 41.51 % lower than unfinned system at 1C discharge. Bioinspired geometry with latent heat storage offers new pathway for passive BTMS in next generation high power energy storage systems.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"257 ","pages":"Article 128238"},"PeriodicalIF":5.8,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-13DOI: 10.1016/j.ijheatmasstransfer.2025.128247
Keisuke Takaara, Hiroya Hoshiba, Koji Nishiguchi, Junji Kato
Despite the effectiveness of fast Fourier transform (FFT)-based methods, their application to microstructural topology optimization in fluid mechanics remains limited. With this background, this study proposes a novel framework combining FFT-based computational homogenization with gradient-based topology optimization for fluid flow problems. A detailed comparison with the finite element method (FEM) shows that the FFT-based solver achieves comparable accuracy while substantially reducing computational time and memory usage. The proposed method is applied to both two- and three-dimensional problems to investigate its feasibility and validity. The objective function is defined as the component of the homogenized permeability tensor, with sensitivities computed via the continuous adjoint method, allowing the same FFT-based scheme for forward and adjoint analyses. Characteristics of the proposed method, including iteration counts and computational time during optimization are discussed. The results confirm the effectiveness of FFT-based computational homogenization for fluidic microstructure design and provide insight into its numerical behavior.
{"title":"Design of microstructures with maximum permeability using FFT-based homogenization method","authors":"Keisuke Takaara, Hiroya Hoshiba, Koji Nishiguchi, Junji Kato","doi":"10.1016/j.ijheatmasstransfer.2025.128247","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128247","url":null,"abstract":"<div><div>Despite the effectiveness of fast Fourier transform (FFT)-based methods, their application to microstructural topology optimization in fluid mechanics remains limited. With this background, this study proposes a novel framework combining FFT-based computational homogenization with gradient-based topology optimization for fluid flow problems. A detailed comparison with the finite element method (FEM) shows that the FFT-based solver achieves comparable accuracy while substantially reducing computational time and memory usage. The proposed method is applied to both two- and three-dimensional problems to investigate its feasibility and validity. The objective function is defined as the component of the homogenized permeability tensor, with sensitivities computed via the continuous adjoint method, allowing the same FFT-based scheme for forward and adjoint analyses. Characteristics of the proposed method, including iteration counts and computational time during optimization are discussed. The results confirm the effectiveness of FFT-based computational homogenization for fluidic microstructure design and provide insight into its numerical behavior.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"257 ","pages":"Article 128247"},"PeriodicalIF":5.8,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-12DOI: 10.1016/j.ijheatmasstransfer.2025.128242
Shuo Yang, Yuyang Qin, Jian Wu
Supercritical carbon dioxide ( 2) has broad application prospects in SCRamjet cooling and thermoelectric conversion systems. This study provides a comprehensive investigation of the thermal–mechanical coupling mechanisms of rib-enhanced heat transfer in regenerative cooling channel. The results show that ribs regulate the spatial distribution of buoyancy and suppress the flow acceleration effect. The upstream side of the rib shows markedly higher local heat flux and thermal stress, which intensify from the rib root toward the rib tip. Thermal stress is identified as the main component of the equivalent stress. Compared with the smooth channel, the ribbed channel reduces the peak equivalent stress by up to 16.9%, while slightly increasing the average stress. Rib height primarily influences the range and intensity of shear layer. Increasing rib height enhances heat transfer but also intensifies stress concentration, shifting the maximum cross-sectional stress from the top wall to the rib. Meanwhile, rib pitch mainly affects the frequency of flow disturbances, and larger pitch results in a significant increase in peak stress. Considering the combined thermal–hydraulic–mechanical effects, the reasonable rib parameters are identified as 0.3–0.35 mm and 9–12 mm. The results provide valuable guidance for heat transfer enhancement and structural optimization in regenerative cooling channel utilizing 2.
{"title":"Effect of rectangular ribs on the thermal–mechanical behavior of supercritical CO 2 in regenerative cooling channel","authors":"Shuo Yang, Yuyang Qin, Jian Wu","doi":"10.1016/j.ijheatmasstransfer.2025.128242","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128242","url":null,"abstract":"<div><div>Supercritical carbon dioxide (<span><math><mi>SCO</mi></math></span> <sub>2</sub>) has broad application prospects in SCRamjet cooling and thermoelectric conversion systems. This study provides a comprehensive investigation of the thermal–mechanical coupling mechanisms of rib-enhanced heat transfer in regenerative cooling channel. The results show that ribs regulate the spatial distribution of buoyancy and suppress the flow acceleration effect. The upstream side of the rib shows markedly higher local heat flux and thermal stress, which intensify from the rib root toward the rib tip. Thermal stress is identified as the main component of the equivalent stress. Compared with the smooth channel, the ribbed channel reduces the peak equivalent stress by up to 16.9%, while slightly increasing the average stress. Rib height primarily influences the range and intensity of shear layer. Increasing rib height enhances heat transfer but also intensifies stress concentration, shifting the maximum cross-sectional stress from the top wall to the rib. Meanwhile, rib pitch mainly affects the frequency of flow disturbances, and larger pitch results in a significant increase in peak stress. Considering the combined thermal–hydraulic–mechanical effects, the reasonable rib parameters are identified as <span><math><mrow><mi>h</mi><mo>=</mo></mrow></math></span> 0.3–0.35 mm and <span><math><mrow><mi>p</mi><mo>=</mo></mrow></math></span> 9–12 mm. The results provide valuable guidance for heat transfer enhancement and structural optimization in regenerative cooling channel utilizing <span><math><mi>SCO</mi></math></span> <sub>2</sub>.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"257 ","pages":"Article 128242"},"PeriodicalIF":5.8,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-12DOI: 10.1016/j.ijheatmasstransfer.2025.128234
Yanhai Wang , Kai Wang , Aitao Zhou , Chao Xu , Haijun Guo , Gang Wang
The research on gas diffusion mechanisms in coal matrix is of great significance to utilize coal gas resource and prevent dynamic disasters. However, the gas transport behavior has significant scale effect, which has great impact on the applicability of gas diffusion models and related research is not yet clear. In this paper, the mercury intrusion porosimetry, N2 adsorption, and CO2 adsorption experiment were carried out to quantitatively study the pore structure of coal particle. Then, the gas diffusion experiment was conducted to obtain the gas desorption-diffusion and adsorption-diffusion characteristics under different pressure. Finally, the applicability differences of gas diffusion models in characterizing gas migration behavior at coal particle scale and coal seam scale were discussed. Results show that the characterization of gas migration in coal exhibits significant scale effects, which is closely related to the coal structure. For millimeter scale coal particles, the bidisperse model, time-based model, and pressure-based model all have good characterization effects. For the on-site scale, the time-based model representation effect is poor due to the neglection of spatial evolution characteristic of gas diffusion coefficient, and the bidisperse model has too many parameters that are difficult to determine. The pressure-based model we proposed contains only two parameters that need to be determined and considers the dynamic evolution characteristics of diffusion coefficient on both temporal and spatial dimensions, which can better characterize the gas diffusion behavior. Through the pressure-based model we have established, the clear and observable gas pressure is correlated with the virtual and unobservable equivalent transport channel resistance, achieving precise description of the gas diffusion coefficient evolution. This research provides an insight into the gas diffusion models and has theoretical guidance significance for gas extraction practice.
{"title":"Difference in gas migration between coal particle and coal seam: An insight into the gas diffusion models","authors":"Yanhai Wang , Kai Wang , Aitao Zhou , Chao Xu , Haijun Guo , Gang Wang","doi":"10.1016/j.ijheatmasstransfer.2025.128234","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128234","url":null,"abstract":"<div><div>The research on gas diffusion mechanisms in coal matrix is of great significance to utilize coal gas resource and prevent dynamic disasters. However, the gas transport behavior has significant scale effect, which has great impact on the applicability of gas diffusion models and related research is not yet clear. In this paper, the mercury intrusion porosimetry, N<sub>2</sub> adsorption, and CO<sub>2</sub> adsorption experiment were carried out to quantitatively study the pore structure of coal particle. Then, the gas diffusion experiment was conducted to obtain the gas desorption-diffusion and adsorption-diffusion characteristics under different pressure. Finally, the applicability differences of gas diffusion models in characterizing gas migration behavior at coal particle scale and coal seam scale were discussed. Results show that the characterization of gas migration in coal exhibits significant scale effects, which is closely related to the coal structure. For millimeter scale coal particles, the bidisperse model, time-based model, and pressure-based model all have good characterization effects. For the on-site scale, the time-based model representation effect is poor due to the neglection of spatial evolution characteristic of gas diffusion coefficient, and the bidisperse model has too many parameters that are difficult to determine. The pressure-based model we proposed contains only two parameters that need to be determined and considers the dynamic evolution characteristics of diffusion coefficient on both temporal and spatial dimensions, which can better characterize the gas diffusion behavior. Through the pressure-based model we have established, the clear and observable gas pressure is correlated with the virtual and unobservable equivalent transport channel resistance, achieving precise description of the gas diffusion coefficient evolution. This research provides an insight into the gas diffusion models and has theoretical guidance significance for gas extraction practice.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"257 ","pages":"Article 128234"},"PeriodicalIF":5.8,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734136","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 work aims at conducting a critical assessment of wall boiling modeling through the Heat Flux Partitioning approach. To do so, a new model dedicated to vertical boiling flows is constructed, with a revisited partitioning including an evaporation heat flux related to bubble coalescence while discussing and assessing each modeling step.
Closure laws include a recent model for bubble dynamics, a new correlation for the bubble maximum lift-off diameter, and comprehensive selection of existing models for nucleation site density and bubble wait time.
Each formulation is compared to relevant existing data from the literature in order to emphasize the importance of separate validation in such a modeling framework.
The whole model is then confronted to detailed wall boiling experiments to simultaneously compare boiling curve predictions along other physical parameters such as boiling time scales (bubble growth, transient conduction, bubble wait), bubble departure frequency, or nucleation site density.
Finally, validation against wall temperature measurements in various conditions are used to assess the model accuracy and further discuss the limits of the Heat Flux Partitioning approach.
{"title":"On physical considerations regarding development and validation of Heat Flux Partitioning models: Application to vertical boiling flows simulations","authors":"Luc Favre , Catherine Colin , Stéphane Pujet , Stéphane Mimouni","doi":"10.1016/j.ijheatmasstransfer.2025.128235","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128235","url":null,"abstract":"<div><div>This work aims at conducting a critical assessment of wall boiling modeling through the Heat Flux Partitioning approach. To do so, a new model dedicated to vertical boiling flows is constructed, with a revisited partitioning including an evaporation heat flux related to bubble coalescence while discussing and assessing each modeling step.</div><div>Closure laws include a recent model for bubble dynamics, a new correlation for the bubble maximum lift-off diameter, and comprehensive selection of existing models for nucleation site density and bubble wait time.</div><div>Each formulation is compared to relevant existing data from the literature in order to emphasize the importance of separate validation in such a modeling framework.</div><div>The whole model is then confronted to detailed wall boiling experiments to simultaneously compare boiling curve predictions along other physical parameters such as boiling time scales (bubble growth, transient conduction, bubble wait), bubble departure frequency, or nucleation site density.</div><div>Finally, validation against wall temperature measurements in various conditions are used to assess the model accuracy and further discuss the limits of the Heat Flux Partitioning approach.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"257 ","pages":"Article 128235"},"PeriodicalIF":5.8,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-12DOI: 10.1016/j.ijheatmasstransfer.2025.128228
Zhigang Xu , Haicheng Qi , Tianyou Wang , Zhenyu Zhang , Zhizhao Che
Droplet propulsion is important in numerous applications, such as microfluidic chips, biomimetic micro-robots, and drug delivery. A droplet on a liquid film always hovers and wets the surface throughout the impact process. In this study, we report a phenomenon in which a droplet on a non-uniformly heated surface exhibited self-propulsion from a cold to a hot surface without wetting. There was a micrometer-sized, or even thinner, gas film beneath the droplet that continuously prevented it from wetting the surface of the liquid film. An experimental investigation on droplet propulsion by color interferometry and high-speed photography showed a gas film beneath the droplet, and the thickness of the gas film was measured during droplet self-propulsion. The propulsion acceleration of the droplet increased linearly with the temperature gradient of the liquid film surface, and a theoretical model was developed to explain the observed self-propulsion of the droplet based on the dynamics of the thin gas film. When the temperature gradient of the liquid film surface was 0, the droplet stayed at the impact point without propulsion, and thus the droplet acceleration was 0. However, when the temperature gradient of the liquid film surface was 10.73 K/mm, the droplet acceleration could even reach 129.3 mm/s2. The diameter of the gas film increased with the droplet size because more gas was entrapped by the larger droplet. As the droplet diameter increased from 1.5 to 2 mm, the diameter of the gas film almost doubled. The effects of the droplet viscosity on the droplet self-propulsion were negligible, but the extremely low-viscosity droplet propelled slowly because of the energy loss in the bouncing process. This self-propulsion can be exploited to manipulate a droplet mediated by thin gas film in specific directions through well-defined temperature gradients.
{"title":"Non-wettability propulsion mediated by the gas film after the impact of droplets","authors":"Zhigang Xu , Haicheng Qi , Tianyou Wang , Zhenyu Zhang , Zhizhao Che","doi":"10.1016/j.ijheatmasstransfer.2025.128228","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128228","url":null,"abstract":"<div><div>Droplet propulsion is important in numerous applications, such as microfluidic chips, biomimetic micro-robots, and drug delivery. A droplet on a liquid film always hovers and wets the surface throughout the impact process. In this study, we report a phenomenon in which a droplet on a non-uniformly heated surface exhibited self-propulsion from a cold to a hot surface without wetting. There was a micrometer-sized, or even thinner, gas film beneath the droplet that continuously prevented it from wetting the surface of the liquid film. An experimental investigation on droplet propulsion by color interferometry and high-speed photography showed a gas film beneath the droplet, and the thickness of the gas film was measured during droplet self-propulsion. The propulsion acceleration of the droplet increased linearly with the temperature gradient of the liquid film surface, and a theoretical model was developed to explain the observed self-propulsion of the droplet based on the dynamics of the thin gas film. When the temperature gradient of the liquid film surface was 0, the droplet stayed at the impact point without propulsion, and thus the droplet acceleration was 0. However, when the temperature gradient of the liquid film surface was 10.73 K/mm, the droplet acceleration could even reach 129.3 mm/s<sup>2</sup>. The diameter of the gas film increased with the droplet size because more gas was entrapped by the larger droplet. As the droplet diameter increased from 1.5 to 2 mm, the diameter of the gas film almost doubled. The effects of the droplet viscosity on the droplet self-propulsion were negligible, but the extremely low-viscosity droplet propelled slowly because of the energy loss in the bouncing process. This self-propulsion can be exploited to manipulate a droplet mediated by thin gas film in specific directions through well-defined temperature gradients.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"257 ","pages":"Article 128228"},"PeriodicalIF":5.8,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734135","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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