Pub Date : 2026-01-28DOI: 10.1016/j.ijheatmasstransfer.2026.128444
Yonghui Liang , Mengjie Song , Long Zhang , Sirui Yu , Qunbo Liu , Jing Cheng
Uniform frosting on the surface of finned heat exchangers in low temperature and high humidity environments can help alleviate the performance degradation of air source heat pumps. Traditional research has mostly focused on system defrosting strategies and optimization of surface wettability of fins, without paying attention to the study of uniform frosting on individual fins. This study proposes a new strategy aimed at inducing uniform frosting on fins by designing convex structures on the surface of the fins. Through systematic experimental observation, the influence of convex structures with different geometric shapes on the full cycle process of condensation and frost growth was studied. The research results indicate that due to the influence of edge effects and center temperature, droplets and frost on the surface of fins without convex structures are distributed in a W-shaped pattern along the airflow direction. At 60 minutes, the non-uniformity of condensate droplet coverage and frost thickness was 11.3% and 0.023 mm, respectively. The effect of inducing condensation and frosting was significant after adding the protruding structure, but it would block the leeward airflow and suppress condensation and frosting. The non-uniformity of droplet coverage of the vertical linear convex structure fins was reduced by 25.0%. After adding the edge convex structure, the gap is less likely to enter humid air, and the non-uniformity of frosting increases by 26.2%. This study can provide important theoretical basis and innovative technological path for the design and management of surface convex structures during frosting process.
{"title":"Experimental study on the influence of convex structures of a single vertical fin on condensation and frosting under constrained airflow conditions","authors":"Yonghui Liang , Mengjie Song , Long Zhang , Sirui Yu , Qunbo Liu , Jing Cheng","doi":"10.1016/j.ijheatmasstransfer.2026.128444","DOIUrl":"10.1016/j.ijheatmasstransfer.2026.128444","url":null,"abstract":"<div><div>Uniform frosting on the surface of finned heat exchangers in low temperature and high humidity environments can help alleviate the performance degradation of air source heat pumps. Traditional research has mostly focused on system defrosting strategies and optimization of surface wettability of fins, without paying attention to the study of uniform frosting on individual fins. This study proposes a new strategy aimed at inducing uniform frosting on fins by designing convex structures on the surface of the fins. Through systematic experimental observation, the influence of convex structures with different geometric shapes on the full cycle process of condensation and frost growth was studied. The research results indicate that due to the influence of edge effects and center temperature, droplets and frost on the surface of fins without convex structures are distributed in a W-shaped pattern along the airflow direction. At 60 minutes, the non-uniformity of condensate droplet coverage and frost thickness was 11.3% and 0.023 mm, respectively. The effect of inducing condensation and frosting was significant after adding the protruding structure, but it would block the leeward airflow and suppress condensation and frosting. The non-uniformity of droplet coverage of the vertical linear convex structure fins was reduced by 25.0%. After adding the edge convex structure, the gap is less likely to enter humid air, and the non-uniformity of frosting increases by 26.2%. This study can provide important theoretical basis and innovative technological path for the design and management of surface convex structures during frosting process.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"260 ","pages":"Article 128444"},"PeriodicalIF":5.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076286","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 : 2026-01-28DOI: 10.1016/j.ijheatmasstransfer.2026.128443
D. Blanco-Muelas , C. Berna-Escriche , J.L. Muñoz-Cobo , I. Atindehou
Steam discharges into subcooled water pools exhibit a behavior that depends strongly on the mass flux of the injected steam and the temperature of the liquid medium, influencing the morphology and dynamic evolution of the resulting jet. An experimental study was conducted using a dedicated experimental facility, where steam is injected under controlled conditions into a pool of stagnant subcooled water, at different condensation regimes. The jet behavior is recorded using a high-speed camera, and the discharge process is analyzed through direct visualization techniques combined with an image processing methodology. Sequences of 18,000 frames are processed to extract parameters such as the mean penetration length and the maximum expansion diameter of the jet. Furthermore, the Fast Fourier Transform is applied to the time series of instantaneous jet lengths to identify the dominant frequencies associated with oscillations driven by direct contact condensation. The results reveal a transition from conical to ellipsoidal shape jets with increasing temperature and mass flux, and an exponential increase in penetration length is observed when pool temperatures exceed 70 ⁰C. Finally, empirical correlations are proposed to estimate some jet geometrical parameters, such as penetration length, and to predict oscillation frequency as a function of dimensionless variables.
{"title":"Jet morphology and oscillations induced by direct contact condensation of steam discharges into a water pool","authors":"D. Blanco-Muelas , C. Berna-Escriche , J.L. Muñoz-Cobo , I. Atindehou","doi":"10.1016/j.ijheatmasstransfer.2026.128443","DOIUrl":"10.1016/j.ijheatmasstransfer.2026.128443","url":null,"abstract":"<div><div>Steam discharges into subcooled water pools exhibit a behavior that depends strongly on the mass flux of the injected steam and the temperature of the liquid medium, influencing the morphology and dynamic evolution of the resulting jet. An experimental study was conducted using a dedicated experimental facility, where steam is injected under controlled conditions into a pool of stagnant subcooled water, at different condensation regimes. The jet behavior is recorded using a high-speed camera, and the discharge process is analyzed through direct visualization techniques combined with an image processing methodology. Sequences of 18,000 frames are processed to extract parameters such as the mean penetration length and the maximum expansion diameter of the jet. Furthermore, the Fast Fourier Transform is applied to the time series of instantaneous jet lengths to identify the dominant frequencies associated with oscillations driven by direct contact condensation. The results reveal a transition from conical to ellipsoidal shape jets with increasing temperature and mass flux, and an exponential increase in penetration length is observed when pool temperatures exceed 70 ⁰C. Finally, empirical correlations are proposed to estimate some jet geometrical parameters, such as penetration length, and to predict oscillation frequency as a function of dimensionless variables.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"260 ","pages":"Article 128443"},"PeriodicalIF":5.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076285","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 : 2026-01-28DOI: 10.1016/j.ijheatmasstransfer.2026.128340
Farhad Mesbah, Javad Siavashi, Mohammad Sharifi
Rising energy demand necessitates efficient use of low-mobility oil resources through thermal methods. This study addresses a critical gap by numerically investigating the effect of heat transfer on multiphase flow at the pore scale, considering both macroscopic and microscopic perspectives simultaneously, focusing on relative permeability () and mechanisms of oil mobilization. Simulations were conducted using the finite volume method (FVM) and the volume of fluid (VOF) approach within OpenFOAM. was evaluated via the unsteady-state technique, incorporating temperature-dependent fluid properties. Initially, the sensitivity of to viscosity ratio () was examined at values of 1, 10, and 50, revealing significant impacts on flow behavior. Subsequently, the effect of water-injection temperature (), ranging from 313 to 393 K, was assessed. Results indicate that increasing temperature enhances oil relative permeability () while water relative permeability () remains largely temperature-independent, except at curve endpoints. Endpoint and increased from 0.66 to 1.00 and 0.83 to 1.00, respectively, as the temperature rose. Elevated temperatures also reduced residual oil saturation () from 0.225 to 0.109 by promoting water penetration into narrower pores and mobilizing trapped oil, leading to the occurrence of the oil ganglion phenomenon. Accordingly, with increasing temperature, oil clusters migrate more rapidly, leading to a reduction in oil volume by 12.4% and 28.9% at 363 K and 393 K, respectively. These findings underscore the crucial role of thermal processes in improving fluid displacement efficiency, highlighting their importance for sustainable subsurface resource management.
{"title":"3D pore-scale digital twin for assessing thermal effects on two-phase flow and relative permeability in Bentheimer sandstone","authors":"Farhad Mesbah, Javad Siavashi, Mohammad Sharifi","doi":"10.1016/j.ijheatmasstransfer.2026.128340","DOIUrl":"10.1016/j.ijheatmasstransfer.2026.128340","url":null,"abstract":"<div><div>Rising energy demand necessitates efficient use of low-mobility oil resources through thermal methods. This study addresses a critical gap by numerically investigating the effect of heat transfer on multiphase flow at the pore scale, considering both macroscopic and microscopic perspectives simultaneously, focusing on relative permeability (<span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span>) and mechanisms of oil mobilization. Simulations were conducted using the finite volume method (FVM) and the volume of fluid (VOF) approach within OpenFOAM. <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> was evaluated via the unsteady-state technique, incorporating temperature-dependent fluid properties. Initially, the sensitivity of <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi></mrow></msub></math></span> to viscosity ratio (<span><math><mi>M</mi></math></span>) was examined at <span><math><mi>M</mi></math></span> values of 1, 10, and 50, revealing significant impacts on flow behavior. Subsequently, the effect of water-injection temperature (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>w</mi><mi>i</mi><mi>n</mi><mi>j</mi></mrow></msub></math></span>), ranging from 313 to 393 K, was assessed. Results indicate that increasing temperature enhances oil relative permeability (<span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi><mi>o</mi></mrow></msub></math></span>) while water relative permeability (<span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi><mi>w</mi></mrow></msub></math></span>) remains largely temperature-independent, except at curve endpoints. Endpoint <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi><mi>o</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>k</mi></mrow><mrow><mi>r</mi><mi>w</mi></mrow></msub></math></span> increased from 0.66 to 1.00 and 0.83 to 1.00, respectively, as the temperature rose. Elevated temperatures also reduced residual oil saturation (<span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>o</mi><mi>r</mi></mrow></msub></math></span>) from 0.225 to 0.109 by promoting water penetration into narrower pores and mobilizing trapped oil, leading to the occurrence of the oil ganglion phenomenon. Accordingly, with increasing temperature, oil clusters migrate more rapidly, leading to a reduction in oil volume by 12.4% and 28.9% at 363 K and 393 K, respectively. These findings underscore the crucial role of thermal processes in improving fluid displacement efficiency, highlighting their importance for sustainable subsurface resource management.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"260 ","pages":"Article 128340"},"PeriodicalIF":5.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075850","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 : 2026-01-28DOI: 10.1016/j.ijheatmasstransfer.2026.128419
Iván Velázquez , Frederiek Demeyer , Miriam Reyes
This paper numerically investigates the thermal-hydraulic performance of a micro shell-and-tube heat exchanger (MSTHE) for application in the thermal recuperator of the innovative oxy-combustion-based NET Power cycle, operating under cycle-relevant part-load conditions. The aim is to support the technological transition from the established printed circuit heat exchangers (PCHE) to MSTHE, which offer a lower inertia, cost-effective, and maintenance-friendly high-performance alternative. To this end, a thermal-hydraulic computational model of the MSTHE was developed, capable of capturing the rapid variation of the supercritical CO2 (scCO2) properties and the partial filmwise condensation of the turbine exhaust gases. Results show that the MSTHE must contain at least 60,000 tubes so that the pressure drop on the tube-side is lower than 1 bar at nominal conditions. The MSTHE effectiveness decreases from 89.2% to 65.1% as the cycle load is reduced from 100% to 20%. The overall heat transfer coefficient decreases gradually between 100% and 40% cycle load, drops sharply between 40% and 30%, and then stabilizes between 30% and 20% cycle load. This stabilization is attributed to the abrupt local increase of the heat capacity on the scCO2-side during the pseudo-critical phase transition, which also enhances local condensation heat release and thickens the condensate film on the shell-side. However, it was found that this phenomenon induces strong axial temperature gradients that may induce thermal stresses, representing a trade-off to the proposed compact design. While the floating microtube bundle of MSTHEs can accommodate these thermal stresses, the rigid compact block structure of PCHE is more prone to damage, revealing an additional key advantage of MSTHEs.
{"title":"Thermal-hydraulic performance assessment of a micro shell-and-tube heat exchanger operating under part-load conditions in the NET Power cycle recuperator","authors":"Iván Velázquez , Frederiek Demeyer , Miriam Reyes","doi":"10.1016/j.ijheatmasstransfer.2026.128419","DOIUrl":"10.1016/j.ijheatmasstransfer.2026.128419","url":null,"abstract":"<div><div>This paper numerically investigates the thermal-hydraulic performance of a micro shell-and-tube heat exchanger (MSTHE) for application in the thermal recuperator of the innovative oxy-combustion-based NET Power cycle, operating under cycle-relevant part-load conditions. The aim is to support the technological transition from the established printed circuit heat exchangers (PCHE) to MSTHE, which offer a lower inertia, cost-effective, and maintenance-friendly high-performance alternative. To this end, a thermal-hydraulic computational model of the MSTHE was developed, capable of capturing the rapid variation of the supercritical CO<sub>2</sub> (scCO<sub>2</sub>) properties and the partial filmwise condensation of the turbine exhaust gases. Results show that the MSTHE must contain at least 60,000 tubes so that the pressure drop on the tube-side is lower than 1 bar at nominal conditions. The MSTHE effectiveness decreases from 89.2% to 65.1% as the cycle load is reduced from 100% to 20%. The overall heat transfer coefficient decreases gradually between 100% and 40% cycle load, drops sharply between 40% and 30%, and then stabilizes between 30% and 20% cycle load. This stabilization is attributed to the abrupt local increase of the heat capacity on the scCO<sub>2</sub>-side during the pseudo-critical phase transition, which also enhances local condensation heat release and thickens the condensate film on the shell-side. However, it was found that this phenomenon induces strong axial temperature gradients that may induce thermal stresses, representing a trade-off to the proposed compact design. While the floating microtube bundle of MSTHEs can accommodate these thermal stresses, the rigid compact block structure of PCHE is more prone to damage, revealing an additional key advantage of MSTHEs.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"260 ","pages":"Article 128419"},"PeriodicalIF":5.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075860","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 : 2026-01-28DOI: 10.1016/j.ijheatmasstransfer.2026.128400
Chuhao Huang , Jun Liu , Lei Gan , Tugen Feng , Haibo Wang , Jie Ren , Wenbin Ye , Peiqing Wang , Zhen Zhang , Xi Lu
This study develops a novel transformation-driven scaled boundary finite element method (SBFEM) framework for the sequentially coupled, time-domain analysis of heat conduction and thermal stress in 3D semi-infinite media. The framework employs a domain partitioning strategy where the unbounded far-field is modeled using scaling surface-based SBFEM. A new coordinate transformation based on geometric similarity between a scaling surface (ξ=0) and boundary surface (ξ=1) is introduced. Departing from traditional point-scaling approaches, this framework introduces a methodological innovation by rigorously handling non-separable Jacobian matrices through a variational derivation, enabling accurate capture of spatial non-uniformity and complex topological features. The transient system is solved by formulating the heat conduction matrix via continued-fraction expansion and integrating in the time domain using the modified precise time step integration method (MPTSIM). The method’s accuracy is validated through benchmarks, demonstrating near-perfect agreement with semi-analytical and FEM results. Critically, this high accuracy is achieved with significantly greater computational efficiency, showing a substantial reduction in both DOFs and CPU time compared to the FEM model. The validated framework is applied to layered thermoelastic half-spaces, revealing that the induced stress field is not linearly proportional to the temperature gradient. Instead, the results demonstrate that the mechanical constraint of the surface layer plays a dominant role in shaping the thermal stress distribution. This finding elucidates a fundamental engineering trade-off between minimizing displacement and reducing stress, underscoring the framework’s capability to capture the intrinsic coupling between thermal and mechanical responses in complex layered media.
{"title":"A novel transformation-driven SBFEM framework for time-domain coupled heat conduction and stress analysis in 3D layered half-spaces","authors":"Chuhao Huang , Jun Liu , Lei Gan , Tugen Feng , Haibo Wang , Jie Ren , Wenbin Ye , Peiqing Wang , Zhen Zhang , Xi Lu","doi":"10.1016/j.ijheatmasstransfer.2026.128400","DOIUrl":"10.1016/j.ijheatmasstransfer.2026.128400","url":null,"abstract":"<div><div>This study develops a novel transformation-driven scaled boundary finite element method (SBFEM) framework for the sequentially coupled, time-domain analysis of heat conduction and thermal stress in 3D semi-infinite media. The framework employs a domain partitioning strategy where the unbounded far-field is modeled using scaling surface-based SBFEM. A new coordinate transformation based on geometric similarity between a scaling surface (<em>ξ</em>=0) and boundary surface (<em>ξ</em>=1) is introduced. Departing from traditional point-scaling approaches, this framework introduces a methodological innovation by rigorously handling non-separable Jacobian matrices through a variational derivation, enabling accurate capture of spatial non-uniformity and complex topological features. The transient system is solved by formulating the heat conduction matrix via continued-fraction expansion and integrating in the time domain using the modified precise time step integration method (MPTSIM). The method’s accuracy is validated through benchmarks, demonstrating near-perfect agreement with semi-analytical and FEM results. Critically, this high accuracy is achieved with significantly greater computational efficiency, showing a substantial reduction in both DOFs and CPU time compared to the FEM model. The validated framework is applied to layered thermoelastic half-spaces, revealing that the induced stress field is not linearly proportional to the temperature gradient. Instead, the results demonstrate that the mechanical constraint of the surface layer plays a dominant role in shaping the thermal stress distribution. This finding elucidates a fundamental engineering trade-off between minimizing displacement and reducing stress, underscoring the framework’s capability to capture the intrinsic coupling between thermal and mechanical responses in complex layered media.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"260 ","pages":"Article 128400"},"PeriodicalIF":5.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146076284","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 : 2026-01-28DOI: 10.1016/j.ijheatmasstransfer.2026.128441
Ke Wang , Hai Sun , Xinyi Zhao , Qian Sang , Xueqiang Guo , Mingzhe Dong
Organic matter (OM), mainly represented by kerogen, is a critical component of shale formations. OM exhibits distinct characteristics compared to inorganic matter in terms of pore structures and fluid-solid interactions. Recent studies have revealed complex transport phenomena within shale pores. However, the mobility of oil within OM remains poorly understood. In this study, oil depletion experiments were conducted using shale and tight sandstone cores to evaluate the influence of OM on flow behavior. Subsequently, a novel pore network modeling framework was developed, which integrates liquid compressibility, pore deformation, and the interaction between OM and oil. The proposed model was validated by comparing the simulated flow rates to those from the experiments. By employing pore network models with varying pore structures, the oil depletion process was simulated to quantify oil mobility within OM and assess its contribution to the overall production performance. When considering the interaction between OM and oil, the contribution of OM to oil production is significantly higher than the fraction of organic pore volume. Increasing OM content and porosity improve the contribution of OM. Neglecting the interaction leads to an underestimation of the OM contribution. Among different OM distribution models, the layered-OM model shows the highest pressure depletion rate, while the single-bulk-OM model exhibits the lowest rate. High clay content slows OM deformation and delays the associated increase in pore pressure, while also inhibiting pressure release within OM. This study provides fundamental insights into the role of OM and microstructural properties in shale oil mobility.
{"title":"Pore-scale characterization of the influence of organic matter on shale oil mobility","authors":"Ke Wang , Hai Sun , Xinyi Zhao , Qian Sang , Xueqiang Guo , Mingzhe Dong","doi":"10.1016/j.ijheatmasstransfer.2026.128441","DOIUrl":"10.1016/j.ijheatmasstransfer.2026.128441","url":null,"abstract":"<div><div>Organic matter (OM), mainly represented by kerogen, is a critical component of shale formations. OM exhibits distinct characteristics compared to inorganic matter in terms of pore structures and fluid-solid interactions. Recent studies have revealed complex transport phenomena within shale pores. However, the mobility of oil within OM remains poorly understood. In this study, oil depletion experiments were conducted using shale and tight sandstone cores to evaluate the influence of OM on flow behavior. Subsequently, a novel pore network modeling framework was developed, which integrates liquid compressibility, pore deformation, and the interaction between OM and oil. The proposed model was validated by comparing the simulated flow rates to those from the experiments. By employing pore network models with varying pore structures, the oil depletion process was simulated to quantify oil mobility within OM and assess its contribution to the overall production performance. When considering the interaction between OM and oil, the contribution of OM to oil production is significantly higher than the fraction of organic pore volume. Increasing OM content and porosity improve the contribution of OM. Neglecting the interaction leads to an underestimation of the OM contribution. Among different OM distribution models, the layered-OM model shows the highest pressure depletion rate, while the single-bulk-OM model exhibits the lowest rate. High clay content slows OM deformation and delays the associated increase in pore pressure, while also inhibiting pressure release within OM. This study provides fundamental insights into the role of OM and microstructural properties in shale oil mobility.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"260 ","pages":"Article 128441"},"PeriodicalIF":5.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075848","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 : 2026-01-28DOI: 10.1016/j.ijheatmasstransfer.2026.128448
Jie Li , Ning Lyu , Xuerun Jing , Yuxin Zhang , Guozeng Feng , Caihua Liang , Xiaosong Zhang , Yuanhao Lin
The growth, coalescence and freezing behaviors of condensed droplets during the initial frosting stage on superhydrophobic surfaces significantly influence subsequent growth rate of frost layer height. Developing efficient regulation methods for condensed droplet behaviors is crucial for enhancing the anti-frosting performance of superhydrophobic surfaces. This work fabricated aluminum surfaces featuring anisotropic microstructural arrays at sub-millimeter scale using nanosecond laser ablation, followed by global superhydrophobic modification of the microstructural metal substrates via an immersion method. By establishing a visualization experimental platform, conducting condensation-frosting experiments on superhydrophobic surfaces with typical topologies, including cylinders, triangular prisms and cuboids. The characteristics of droplet condensation and freezing behaviors, freezing front propagation velocity and subsequent frost layer growth properties on these diverse surfaces were obtained. This revealed the multifaceted influence mechanisms of microstructural topology on multi-scale droplet dynamics and surface frosting process. Results demonstrate that sub-millimeter scale microstructures influence frequency of coalescence, coalescence-induced bouncing and multi-droplet coalescence of small-scale droplets during the initial stage of condensed droplet clusters growth, thereby affecting droplet clusters size distribution. Its anisotropy subsequently influences the spatial distribution of large-scale droplets during the later growth stage. Together, these factors influence the droplet freezing time and freezing front propagation velocity. Among the three typical microstructural topologies, the triangular prism microstructure exhibited the most effective anti-frosting performance. Compared with a ordinary superhydrophobic surface, it prolonged the completely freeze time of surface by 106.87 % and reduced growth rate of frost layer height by 27.59 %.
{"title":"Effects of anisotropic sub-millimeter microstructures on condensation and frosting characteristics of superhydrophobic surfaces","authors":"Jie Li , Ning Lyu , Xuerun Jing , Yuxin Zhang , Guozeng Feng , Caihua Liang , Xiaosong Zhang , Yuanhao Lin","doi":"10.1016/j.ijheatmasstransfer.2026.128448","DOIUrl":"10.1016/j.ijheatmasstransfer.2026.128448","url":null,"abstract":"<div><div>The growth, coalescence and freezing behaviors of condensed droplets during the initial frosting stage on superhydrophobic surfaces significantly influence subsequent growth rate of frost layer height. Developing efficient regulation methods for condensed droplet behaviors is crucial for enhancing the anti-frosting performance of superhydrophobic surfaces. This work fabricated aluminum surfaces featuring anisotropic microstructural arrays at sub-millimeter scale using nanosecond laser ablation, followed by global superhydrophobic modification of the microstructural metal substrates via an immersion method. By establishing a visualization experimental platform, conducting condensation-frosting experiments on superhydrophobic surfaces with typical topologies, including cylinders, triangular prisms and cuboids. The characteristics of droplet condensation and freezing behaviors, freezing front propagation velocity and subsequent frost layer growth properties on these diverse surfaces were obtained. This revealed the multifaceted influence mechanisms of microstructural topology on multi-scale droplet dynamics and surface frosting process. Results demonstrate that sub-millimeter scale microstructures influence frequency of coalescence, coalescence-induced bouncing and multi-droplet coalescence of small-scale droplets during the initial stage of condensed droplet clusters growth, thereby affecting droplet clusters size distribution. Its anisotropy subsequently influences the spatial distribution of large-scale droplets during the later growth stage. Together, these factors influence the droplet freezing time and freezing front propagation velocity. Among the three typical microstructural topologies, the triangular prism microstructure exhibited the most effective anti-frosting performance. Compared with a ordinary superhydrophobic surface, it prolonged the completely freeze time of surface by 106.87 % and reduced growth rate of frost layer height by 27.59 %.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"260 ","pages":"Article 128448"},"PeriodicalIF":5.8,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075849","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 : 2026-01-27DOI: 10.1016/j.ijheatmasstransfer.2026.128424
Yunping Yang , Xiaosong Li , Hongjin Zhang , Yuchun Zhang , Tao Li
Tunnel fires frequently induce severe secondary disasters, and a major challenge in their prevention and control lies in the quantitative characterization of dynamic fire behavior. In this study, small-scale tunnel fire experiments were carried out to obtain non-steady combustion data of wood crib fuels under various ventilation conditions. By employing data fusion techniques, key physical features reflecting fire dynamics, such as flame width, were extracted from flame image sequences and combined with other monitoring data to form a unified time-series feature vector. Based on this, the combustion zone was systematically divided into latent-heat, active, and smoldering zones, revealing the synchronous evolution of heat release rate and effective combustion width under different fire loads and longitudinal wind speeds. Further results demonstrate that the primary heat release originates from the effective combustion zone. For example, at a wood crib length of 300 mm, the heat release rate reached 15.6 kW and increased to 39 kW with a higher fuel mass per unit length. Building on these findings, this study innovatively developed a full-process transient heat release rate prediction model grounded in the effective combustion zone framework, together with a model for predicting the maximum temperature rise beneath the tunnel ceiling, achieving an accuracy within 10%. The proposed methodology effectively quantifies the complete dynamic characteristics of solid fuel fires and provides a new theoretical tool and practical reference for risk assessment and prevention design in tunnel fire safety.
{"title":"Combustion model of effective-potential fire loads based on data fusion: Quantitative methods for predicting solid fuel fires in tunnel","authors":"Yunping Yang , Xiaosong Li , Hongjin Zhang , Yuchun Zhang , Tao Li","doi":"10.1016/j.ijheatmasstransfer.2026.128424","DOIUrl":"10.1016/j.ijheatmasstransfer.2026.128424","url":null,"abstract":"<div><div>Tunnel fires frequently induce severe secondary disasters, and a major challenge in their prevention and control lies in the quantitative characterization of dynamic fire behavior. In this study, small-scale tunnel fire experiments were carried out to obtain non-steady combustion data of wood crib fuels under various ventilation conditions. By employing data fusion techniques, key physical features reflecting fire dynamics, such as flame width, were extracted from flame image sequences and combined with other monitoring data to form a unified time-series feature vector. Based on this, the combustion zone was systematically divided into latent-heat, active, and smoldering zones, revealing the synchronous evolution of heat release rate and effective combustion width under different fire loads and longitudinal wind speeds. Further results demonstrate that the primary heat release originates from the effective combustion zone. For example, at a wood crib length of 300 mm, the heat release rate reached 15.6 kW and increased to 39 kW with a higher fuel mass per unit length. Building on these findings, this study innovatively developed a full-process transient heat release rate prediction model grounded in the effective combustion zone framework, together with a model for predicting the maximum temperature rise beneath the tunnel ceiling, achieving an accuracy within 10%. The proposed methodology effectively quantifies the complete dynamic characteristics of solid fuel fires and provides a new theoretical tool and practical reference for risk assessment and prevention design in tunnel fire safety.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"260 ","pages":"Article 128424"},"PeriodicalIF":5.8,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075865","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 : 2026-01-27DOI: 10.1016/j.ijheatmasstransfer.2026.128436
Jue Wang , Jiayu Kang , Cheng Jiang , Shixuan Yu , Gang Bai
This study investigates the flow structure and heat transfer characteristics of transversely superimposed multi-jet-in-crossflow (JICF) systems at a low velocity ratio (R = 0.5, defined as the ratio of jet velocity to crossflow velocity) with varying jet-to-jet spacings (ds/dj = 2–18). The method of combining experiment and simulation was employed to resolve vortex dynamics, thermal fields, and field synergy distributions. A vortex-zone classification framework was developed, dividing the downstream region into strong attachment, weak attachment, fragmentation, and dissipation zones based on normalized vorticity. Results show that positioning the rear-stage jet within the strong attachment zone of the upstream jet enhances convective heat transfer through intensified field synergy, but shortens the downstream cooling persistence due to accelerated thermal diffusion. Conversely, placing it in the fragmentation zone improves cold fluid retention, yielding up to 50% higher cooling effectiveness at 20 dj compared with single-stage configurations. The findings provide a quantitative basis for optimizing vent spacing to balance near-wall heat transfer and far-field thermal insulation, with implications for turbine blade cooling, electronic thermal management, and mine ventilation.
{"title":"Effect of vent spacing on flow structure and heat transfer of transversely superimposed jets in crossflow at low velocity ratio","authors":"Jue Wang , Jiayu Kang , Cheng Jiang , Shixuan Yu , Gang Bai","doi":"10.1016/j.ijheatmasstransfer.2026.128436","DOIUrl":"10.1016/j.ijheatmasstransfer.2026.128436","url":null,"abstract":"<div><div>This study investigates the flow structure and heat transfer characteristics of transversely superimposed multi-jet-in-crossflow (JICF) systems at a low velocity ratio (<em>R</em> = 0.5, defined as the ratio of jet velocity to crossflow velocity) with varying jet-to-jet spacings (<em>d</em><sub>s</sub><em>/d</em><sub>j</sub> = 2–18). The method of combining experiment and simulation was employed to resolve vortex dynamics, thermal fields, and field synergy distributions. A vortex-zone classification framework was developed, dividing the downstream region into strong attachment, weak attachment, fragmentation, and dissipation zones based on normalized vorticity. Results show that positioning the rear-stage jet within the strong attachment zone of the upstream jet enhances convective heat transfer through intensified field synergy, but shortens the downstream cooling persistence due to accelerated thermal diffusion. Conversely, placing it in the fragmentation zone improves cold fluid retention, yielding up to 50% higher cooling effectiveness at 20 <em>d</em><sub>j</sub> compared with single-stage configurations. The findings provide a quantitative basis for optimizing vent spacing to balance near-wall heat transfer and far-field thermal insulation, with implications for turbine blade cooling, electronic thermal management, and mine ventilation.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"260 ","pages":"Article 128436"},"PeriodicalIF":5.8,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075866","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 : 2026-01-25DOI: 10.1016/j.ijheatmasstransfer.2026.128415
Wenzhu Luo , Ershuai Yin , Lei Wang, Enjian Sun, Qiang Li
The AlxGa(1-x)N-GaN heterostructure two-dimensional electron gas channel (2DEG) serves as the core for both conduction and heat generation in GaN HEMTs. Meanwhile, due to the regulation of device performance by strain engineering and the differences in material properties between heterostructure materials, external loads, inverse piezoelectric stress, thermal stresses, and residual stresses all exert a significant influence on the heat transfer process within heterostructures. However, the effect of strain on heat transfer and local phonon transport properties at the AlxGa(1-x)N-GaN interface remains unclear. This study employs machine learning-based Neuroevolution Potential (NEP) molecular dynamics simulations to investigate the thermal transport mechanisms in AlxGa(1-x)N-GaN and AlxGa(1-x)N-AlN-GaN heterostructures under both compressive and tensile strains. Research indicates that the rate of increase in interfacial thermal conductance (ITC) accelerates as compressive strain intensity rises, and at 8% compressive strain, the ITC of Al0.2 Ga0.8N-GaN and Al0.2Ga0.8N-AlN-GaN increases by 19.1% and 236%, respectively, compared to the unstrained condition. Compressional strain increases the overlap region of the low-frequency phonon density of states (PDOS), enhances scattering between interfacial phonons, and distributes more energy into low-frequency phonon modes, which are more conducive to interfacial heat transfer, thereby enhancing heat transport at the heterostructure. Tensile strain weakens high-frequency phonon transport processes but additionally excites mid-frequency localized phonon transport channels, so its effect on the ITC is not significant. This study provides a crucial theoretical foundation for stress control in the manufacturing process of GaN-based electronic devices and for enhancing interfacial heat transport through stress regulation.
AlxGa(1-x)N-GaN异质结构二维电子气通道（2DEG）是GaN hemt中传导和产热的核心。同时，由于应变工程对器件性能的调控以及异质结构材料之间材料性能的差异，外载荷、逆压电应力、热应力、残余应力等都对异质结构内部的传热过程产生重要影响。然而，应变对AlxGa(1-x)N-GaN界面的传热和局部声子输运性质的影响尚不清楚。本研究采用基于机器学习的神经进化电位（NEP）分子动力学模拟研究了压缩应变和拉伸应变下AlxGa(1-x)N-GaN和AlxGa(1-x)N-AlN-GaN异质结构中的热传递机制。研究表明，随着压缩应变强度的增加，界面热导率（ITC）的增加速度加快，在压缩应变为8%时，Al0.2 Ga0.8N-GaN和Al0.2 ga0.8 n - aln - gan的界面热导率（ITC）分别比未变形时提高了19.1%和236%。压缩应变增加了低频声子态密度（PDOS）的重叠区域，增强了界面声子之间的散射，将更多的能量分配到更有利于界面传热的低频声子模式中，从而增强了异质结构处的热传递。拉伸应变削弱了高频声子输运过程，但也激发了中频局域声子输运通道，因此对ITC的影响不显著。该研究为氮化镓电子器件制造过程中的应力控制以及通过应力调节增强界面热传递提供了重要的理论基础。
{"title":"Interfacial thermal transport of AlxGa(1-x)N-GaN heterostructures under strain via machine learning potential","authors":"Wenzhu Luo , Ershuai Yin , Lei Wang, Enjian Sun, Qiang Li","doi":"10.1016/j.ijheatmasstransfer.2026.128415","DOIUrl":"10.1016/j.ijheatmasstransfer.2026.128415","url":null,"abstract":"<div><div>The Al<sub>x</sub>Ga<sub>(1-x)</sub>N-GaN heterostructure two-dimensional electron gas channel (2DEG) serves as the core for both conduction and heat generation in GaN HEMTs. Meanwhile, due to the regulation of device performance by strain engineering and the differences in material properties between heterostructure materials, external loads, inverse piezoelectric stress, thermal stresses, and residual stresses all exert a significant influence on the heat transfer process within heterostructures. However, the effect of strain on heat transfer and local phonon transport properties at the Al<sub>x</sub>Ga<sub>(1-x)</sub>N-GaN interface remains unclear. This study employs machine learning-based Neuroevolution Potential (NEP) molecular dynamics simulations to investigate the thermal transport mechanisms in Al<sub>x</sub>Ga<sub>(1-x)</sub>N-GaN and Al<sub>x</sub>Ga<sub>(1-x)</sub>N-AlN-GaN heterostructures under both compressive and tensile strains. Research indicates that the rate of increase in interfacial thermal conductance (ITC) accelerates as compressive strain intensity rises, and at 8% compressive strain, the ITC of Al<sub>0.2</sub> Ga<sub>0.8</sub>N-GaN and Al<sub>0.2</sub>Ga<sub>0.8</sub>N-AlN-GaN increases by 19.1% and 236%, respectively, compared to the unstrained condition. Compressional strain increases the overlap region of the low-frequency phonon density of states (PDOS), enhances scattering between interfacial phonons, and distributes more energy into low-frequency phonon modes, which are more conducive to interfacial heat transfer, thereby enhancing heat transport at the heterostructure. Tensile strain weakens high-frequency phonon transport processes but additionally excites mid-frequency localized phonon transport channels, so its effect on the ITC is not significant. This study provides a crucial theoretical foundation for stress control in the manufacturing process of GaN-based electronic devices and for enhancing interfacial heat transport through stress regulation.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"260 ","pages":"Article 128415"},"PeriodicalIF":5.8,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146075861","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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