Pub Date : 2025-11-28DOI: 10.1016/j.ijheatmasstransfer.2025.128201
Kentaro Kanatani
Laminar film condensation of upward pure vapor flow in a vertical tube is studied by numerically solving approximate integral two-phase boundary layer equations. Depending upon the boundary condition, three types of solution are examined: (i) zero film thickness at the bottom, (ii) zero flow rate with a finite film thickness at the bottom, and (iii) negative flow rates (the downward drainage of the condensate) at the bottom. The film thickness, the average Nusselt number and the pressure variation are obtained from the solution of the model equations. The numerical results indicate that the decrease in the tube radius thickens the film layer and decreases the average Nusselt number for the solution type (i) while it thins the film and increases the Nusselt number for the solution type (ii). The maximum tube lengths for the solution types (i) and (ii) are calculated against the degree of subcooling and curvature of the tube. As the degree of subcooling increases, the maximum length for the solution type (i) decreases for sufficiently small tube radii, but increases for the flat-plate case. Furthermore, the results are compared with those of an asymptotic solution in the limit of large degrees of subcooling. The asymptotic solution is a good approximation except for the film thickness and the maximum tube length. Moreover, the tube length of complete condensation is estimated. The tube length of complete condensation is smaller for larger degrees of subcooling and smaller tube radii.
{"title":"Flow regimes for laminar film condensation of upward vapor flow in a vertical tube","authors":"Kentaro Kanatani","doi":"10.1016/j.ijheatmasstransfer.2025.128201","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128201","url":null,"abstract":"<div><div>Laminar film condensation of upward pure vapor flow in a vertical tube is studied by numerically solving approximate integral two-phase boundary layer equations. Depending upon the boundary condition, three types of solution are examined: (i) zero film thickness at the bottom, (ii) zero flow rate with a finite film thickness at the bottom, and (iii) negative flow rates (the downward drainage of the condensate) at the bottom. The film thickness, the average Nusselt number and the pressure variation are obtained from the solution of the model equations. The numerical results indicate that the decrease in the tube radius thickens the film layer and decreases the average Nusselt number for the solution type (i) while it thins the film and increases the Nusselt number for the solution type (ii). The maximum tube lengths for the solution types (i) and (ii) are calculated against the degree of subcooling and curvature of the tube. As the degree of subcooling increases, the maximum length for the solution type (i) decreases for sufficiently small tube radii, but increases for the flat-plate case. Furthermore, the results are compared with those of an asymptotic solution in the limit of large degrees of subcooling. The asymptotic solution is a good approximation except for the film thickness and the maximum tube length. Moreover, the tube length of complete condensation is estimated. The tube length of complete condensation is smaller for larger degrees of subcooling and smaller tube radii.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"256 ","pages":"Article 128201"},"PeriodicalIF":5.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620632","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}
Heat dissipation of transition metal dichalcogenides has been a major obstacle in their application in high-performance devices. Heat-spreading interlayers play a critical role in dissipating Joule heat from the device to the substrate. To select the material as the interlayer, the electric, thermal, and phonon properties are widely considered, while the mechanical properties are generally overlooked. Here, we demonstrate that the flexural rigidity, a mechanical property, is another critical factor. Molecular dynamics simulations suggest that interfacial thermal conductance provided by an interlayer with low flexural rigidity generally surpasses that provided by an interlayer with the same phonon spectra as the device. Mechanism analyses indicate that the interlayer with lower flexural rigidity possesses a higher degree of conformal attachment to both the device and the substrate, which facilitates the phonon transmission across the interface. To decouple the effects of flexural rigidity and phonon resonance, two groups of model systems containing interlayers with various but independent flexural rigidities and phonon spectra are constructed and investigated. Reducing the flexural rigidity to 33% can enhance the interfacial thermal conductance by 60%. A scaling law of the interfacial thermal conductance is established according to the flexural rigidity and the phonon overlap coefficient, validated by interlayers of five different materials. These results provide theoretical insights into thermal transport across heterogeneous van der Waals junctions and offer guidance for the thermal management of high-power-density devices enabled by two-dimensional materials.
{"title":"Enhancing device-to-substrate thermal transport by limiting the flexural rigidity of heat-spreading interlayers","authors":"Xiaotong Yu , Kai Chen , Weiyan Chen , Ziqiao Chen , Haozhe Zhang , Baoxing Xu , Rong Chen , Yuan Gao","doi":"10.1016/j.ijheatmasstransfer.2025.128180","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128180","url":null,"abstract":"<div><div>Heat dissipation of transition metal dichalcogenides has been a major obstacle in their application in high-performance devices. Heat-spreading interlayers play a critical role in dissipating Joule heat from the device to the substrate. To select the material as the interlayer, the electric, thermal, and phonon properties are widely considered, while the mechanical properties are generally overlooked. Here, we demonstrate that the flexural rigidity, a mechanical property, is another critical factor. Molecular dynamics simulations suggest that interfacial thermal conductance provided by an interlayer with low flexural rigidity generally surpasses that provided by an interlayer with the same phonon spectra as the device. Mechanism analyses indicate that the interlayer with lower flexural rigidity possesses a higher degree of conformal attachment to both the device and the substrate, which facilitates the phonon transmission across the interface. To decouple the effects of flexural rigidity and phonon resonance, two groups of model systems containing interlayers with various but independent flexural rigidities and phonon spectra are constructed and investigated. Reducing the flexural rigidity to 33% can enhance the interfacial thermal conductance by 60%. A scaling law of the interfacial thermal conductance is established according to the flexural rigidity and the phonon overlap coefficient, validated by interlayers of five different materials. These results provide theoretical insights into thermal transport across heterogeneous van der Waals junctions and offer guidance for the thermal management of high-power-density devices enabled by two-dimensional materials.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"256 ","pages":"Article 128180"},"PeriodicalIF":5.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620540","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 : 2025-11-28DOI: 10.1016/j.ijheatmasstransfer.2025.128080
Ilan Pinkus , Woo Young Park , Vishwanath Ganesan , Omar M. Zaki , Trevor G. Aguirre , Kashif Nawaz , Nenad Miljkovic , William P. King
Modern and future data centers face increasing cooling challenges due to increasing chip thermal design power and die size, along with the need to reduce energy consumption used for cooling. High performance cooling solutions that maintain a low chip junction temperature are needed to ensure electronics reliability. This work develops an ultra-low thermal resistance and low pressure drop 75 mm × 75 mm cold plate, intended for next-generation electronics cooling. The cold plate features an array of diamond-shaped pin fins and integrated copper tungsten heat spreader, selected for its low coefficient of thermal expansion which reduces thermomechanical deformation and allows for closer integration of the cold plate with silicon dies. Starting with 300 candidate designs, three-dimensional computational fluid dynamics simulations predict the thermal-hydraulic performance of cold plate subsections. The highest performing geometries are evaluated with high fidelity simulations. Four cold plates are manufactured for experiments: three with diamond-shaped pin fins and one with straights fins for comparison purposes. The cold plates are fabricated from copper-tungsten (CuW), copper (Cu), or aluminum-silicon-magnesium alloy (AlSi10Mg). The diamond-shaped pin fins achieve a roughly 15 % lower thermal resistance compared to the conventional straight fin microchannel. The highest performing design achieves a chip-to-coolant (including thermal interface material) thermal resistance of 9.0 K/kW in CuW and 6.9 K/kW in Cu under a 1 kW heat load with an inlet-to-outlet pressure drop of 9.0 kPa and water as the working fluid. This work demonstrates ultra-low thermal resistance and pressure drop cold plates for large die, high heat load applications, and shows that CuW is an attractive cold plate material for improved reliability in next generation data center cooling.
{"title":"Ultra-low thermal resistance and pressure drop copper and copper-tungsten diamond-shaped pin fin cold plates for liquid cooling of electronics","authors":"Ilan Pinkus , Woo Young Park , Vishwanath Ganesan , Omar M. Zaki , Trevor G. Aguirre , Kashif Nawaz , Nenad Miljkovic , William P. King","doi":"10.1016/j.ijheatmasstransfer.2025.128080","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128080","url":null,"abstract":"<div><div>Modern and future data centers face increasing cooling challenges due to increasing chip thermal design power and die size, along with the need to reduce energy consumption used for cooling. High performance cooling solutions that maintain a low chip junction temperature are needed to ensure electronics reliability. This work develops an ultra-low thermal resistance and low pressure drop 75 mm × 75 mm cold plate, intended for next-generation electronics cooling. The cold plate features an array of diamond-shaped pin fins and integrated copper tungsten heat spreader, selected for its low coefficient of thermal expansion which reduces thermomechanical deformation and allows for closer integration of the cold plate with silicon dies. Starting with 300 candidate designs, three-dimensional computational fluid dynamics simulations predict the thermal-hydraulic performance of cold plate subsections. The highest performing geometries are evaluated with high fidelity simulations. Four cold plates are manufactured for experiments: three with diamond-shaped pin fins and one with straights fins for comparison purposes. The cold plates are fabricated from copper-tungsten (CuW), copper (Cu), or aluminum-silicon-magnesium alloy (AlSi10Mg). The diamond-shaped pin fins achieve a roughly 15 % lower thermal resistance compared to the conventional straight fin microchannel. The highest performing design achieves a chip-to-coolant (including thermal interface material) thermal resistance of 9.0 K/kW in CuW and 6.9 K/kW in Cu under a 1 kW heat load with an inlet-to-outlet pressure drop of 9.0 kPa and water as the working fluid. This work demonstrates ultra-low thermal resistance and pressure drop cold plates for large die, high heat load applications, and shows that CuW is an attractive cold plate material for improved reliability in next generation data center cooling.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"256 ","pages":"Article 128080"},"PeriodicalIF":5.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620636","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 : 2025-11-28DOI: 10.1016/j.ijheatmasstransfer.2025.128153
Hangjie Li , Junming Zhao
Surface plasmon polaritons (SPPs) and magnetic polaritons (MPs) are fundamental resonance modes that are widely used to tailor the thermal radiation properties of micro/nanostructured metamaterials. Lumped circuit models (LCMs) are usually constructed empirically to describe the MP resonance conditions, and different LCMs have to be constructed for different orders of MPs, but these are difficult to be built for high-order MP modes due to the complex electromagnetic field distribution. This work proposes a new type of circuit model, distributed circuit model (DCM), to describe and predict multi-order MP resonances inside the structure based on the minimum total impedance condition. This allows both fundamental and high-order MP resonances to be predicted with a unified circuit, significantly simplifying the analysis of high-order MPs. More importantly, the DCM shares a similar and clear physical picture as the LCM for describing MPs. The MP resonance conditions for four typical structures are derived. Theoretical predictions based on DCMs are compared with and validated by rigorous numerical simulations. This study deepens the understanding and facilitates the design of MP-based thermal radiation metamaterials.
{"title":"Predicting multi-order magnetic polariton resonances for radiative properties tailoring by distributed circuit model","authors":"Hangjie Li , Junming Zhao","doi":"10.1016/j.ijheatmasstransfer.2025.128153","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128153","url":null,"abstract":"<div><div>Surface plasmon polaritons (SPPs) and magnetic polaritons (MPs) are fundamental resonance modes that are widely used to tailor the thermal radiation properties of micro/nanostructured metamaterials. Lumped circuit models (LCMs) are usually constructed empirically to describe the MP resonance conditions, and different LCMs have to be constructed for different orders of MPs, but these are difficult to be built for high-order MP modes due to the complex electromagnetic field distribution. This work proposes a new type of circuit model, distributed circuit model (DCM), to describe and predict multi-order MP resonances inside the structure based on the minimum total impedance condition. This allows both fundamental and high-order MP resonances to be predicted with a unified circuit, significantly simplifying the analysis of high-order MPs. More importantly, the DCM shares a similar and clear physical picture as the LCM for describing MPs. The MP resonance conditions for four typical structures are derived. Theoretical predictions based on DCMs are compared with and validated by rigorous numerical simulations. This study deepens the understanding and facilitates the design of MP-based thermal radiation metamaterials.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"256 ","pages":"Article 128153"},"PeriodicalIF":5.8,"publicationDate":"2025-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620542","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 : 2025-11-27DOI: 10.1016/j.ijheatmasstransfer.2025.128148
D.V. Antonov, O.V. Vetlugaeva, P.A. Strizhak
This study presents experimental and theoretical findings on the characteristics of nonequilibrium processes during microwave heating of immiscible liquid films. Experiments were conducted using a laboratory-scale microwave reactor, with modeling performed in COMSOL Multiphysics. The films were composed of water and sunflower oil in volume ratios of 9:1, 7:3, 1:1, 3:7, and 1:9. In parametric studies, the total volumes of the films ranged from 1 ml to 1 l, while the microwave heating power density ranged from 10 to 104 MW/m3. Through mathematical processing of the results, dimensionless expressions were derived to predict the characteristics of nonequilibrium processes induced by microwave heating of the films. These findings provide a scientific basis for selecting optimal thermal operating conditions for chemical reactors and medical probes.
本文对非混相液膜微波加热非平衡过程的特性进行了实验和理论研究。实验使用实验室规模的微波反应器进行，并在COMSOL Multiphysics中进行建模。膜由水和葵花籽油按9:1、7:3、1:1、3:7和1:9的体积比组成。在参数化研究中，膜的总体积为1 ml ~ 1 l，微波加热功率密度为10 ~ 104 MW/m3。通过对结果的数学处理，导出了微波加热引起的薄膜非平衡过程特征的无量纲表达式。这些研究结果为化学反应器和医用探针的最佳热操作条件的选择提供了科学依据。
{"title":"Nonequilibrium processes induced by microwave heating of immiscible liquid films: Experimental research and mathematical modeling","authors":"D.V. Antonov, O.V. Vetlugaeva, P.A. Strizhak","doi":"10.1016/j.ijheatmasstransfer.2025.128148","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128148","url":null,"abstract":"<div><div>This study presents experimental and theoretical findings on the characteristics of nonequilibrium processes during microwave heating of immiscible liquid films. Experiments were conducted using a laboratory-scale microwave reactor, with modeling performed in COMSOL Multiphysics. The films were composed of water and sunflower oil in volume ratios of 9:1, 7:3, 1:1, 3:7, and 1:9. In parametric studies, the total volumes of the films ranged from 1 ml to 1 l, while the microwave heating power density ranged from 10 to 10<sup>4</sup> MW/m<sup>3</sup>. Through mathematical processing of the results, dimensionless expressions were derived to predict the characteristics of nonequilibrium processes induced by microwave heating of the films. These findings provide a scientific basis for selecting optimal thermal operating conditions for chemical reactors and medical probes.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"256 ","pages":"Article 128148"},"PeriodicalIF":5.8,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620427","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 : 2025-11-27DOI: 10.1016/j.ijheatmasstransfer.2025.128188
Salar Zamani Salimi , Andrea Gruber , Nicolò Scapin , Luca Brandt
This study presents direct numerical simulation (DNS) of finite-size, interface-resolved ammonia and n-heptane droplets evaporating in decaying homogeneous isotropic turbulence. Simulations are conducted for each fuel to model the dynamics in a dense spray region, where the liquid volume fraction exceeds . The focus is on investigating the complex interactions between droplets, turbulence, and phase change, with emphasis on droplet-droplet interactions and their influence on the evaporation process. In detail, we explore the impact of turbulence intensity on (i) coalescence dynamics (via the evolution of droplet number and size distribution) and (ii) interfacial energy transfer, quantified by evaporation rates. The results reveal that, when comparing ammonia with n-heptane with equal liquid volume fractions, ammonia exhibits faster initial evaporation due to its higher volatility. However, this rate declines over time as frequent droplet coalescence reduces the total surface area available for evaporation. When numerical experiments are initialized with equal energy content, increasing turbulence intensity enhances the evaporation of n-heptane throughout the simulation, while ammonia evaporation soon becomes less sensitive to turbulence due to rapid vapor saturation. These findings are relevant to improving predictive CFD models and optimizing fuel injection in spray-combustion applications, especially under high-pressure conditions.
{"title":"Evaporation of finite-size ammonia and n-heptane droplets in weakly compressible turbulence: An interface-resolved DNS study","authors":"Salar Zamani Salimi , Andrea Gruber , Nicolò Scapin , Luca Brandt","doi":"10.1016/j.ijheatmasstransfer.2025.128188","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128188","url":null,"abstract":"<div><div>This study presents direct numerical simulation (DNS) of finite-size, interface-resolved ammonia and n-heptane droplets evaporating in decaying homogeneous isotropic turbulence. Simulations are conducted for each fuel to model the dynamics in a dense spray region, where the liquid volume fraction exceeds <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mo>)</mo></mrow></mrow></math></span>. The focus is on investigating the complex interactions between droplets, turbulence, and phase change, with emphasis on droplet-droplet interactions and their influence on the evaporation process. In detail, we explore the impact of turbulence intensity on (i) coalescence dynamics (via the evolution of droplet number and size distribution) and (ii) interfacial energy transfer, quantified by evaporation rates. The results reveal that, when comparing ammonia with n-heptane with equal liquid volume fractions, ammonia exhibits faster initial evaporation due to its higher volatility. However, this rate declines over time as frequent droplet coalescence reduces the total surface area available for evaporation. When numerical experiments are initialized with equal energy content, increasing turbulence intensity enhances the evaporation of n-heptane throughout the simulation, while ammonia evaporation soon becomes less sensitive to turbulence due to rapid vapor saturation. These findings are relevant to improving predictive CFD models and optimizing fuel injection in spray-combustion applications, especially under high-pressure conditions.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"256 ","pages":"Article 128188"},"PeriodicalIF":5.8,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620545","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}
With the surge in heat flux densities in compact electronic and contemporary thermal systems, heat pipes have emerged as vital passive thermal management solutions. The wick, critical to heat pipe performance, governs liquid circulation and capillary pumping. However, conventional mono-wick designs often demonstrate a trade-off between capillary force and permeability, limiting their effectiveness. Composite wick structures, combining two or more wicks such as sintered powder, mesh, grooves, and spiral woven mesh (SWM), have received significant attention for facilitating an optimised balance between these conflicting properties. Despite this growing research on composite wicks, no review has analysed their advancement and influence on heat pipe performance in comprehensive detail. Addressing this gap, the present work systematically reviews the performance of composite wick designs in cylindrical, flat, and looped heat pipes, with a focus on hydrodynamic and thermal performance characteristics such as permeability, thermal resistance, and heat transport capacity. Studies show that composite wicks can achieve up to 56 % higher performance and thermal resistances as low as 0.02 K/W for some cases. The review also underlines how operating conditions such as fluid charge ratio, orientation, and heat input affect the thermal performance of heat pipes with composite wicks. By synthesising key insights from different studies, this study provides a thorough assessment on the design and fabrication of composite wick-based heat pipes. The findings underscore the critical role of composite wicks in advancing next-generation thermal management systems and shaping future directions for scalable and highly effective heat pipe devices.
{"title":"A systematic review of composite wick designs for enhancing capillary and thermal performance in heat pipes","authors":"Pramod Vishwakarma , Jeff Punch , Eoin Guinan , Bivas Panigrahi , Vanessa Egan","doi":"10.1016/j.ijheatmasstransfer.2025.128130","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128130","url":null,"abstract":"<div><div>With the surge in heat flux densities in compact electronic and contemporary thermal systems, heat pipes have emerged as vital passive thermal management solutions. The wick, critical to heat pipe performance, governs liquid circulation and capillary pumping. However, conventional mono-wick designs often demonstrate a trade-off between capillary force and permeability, limiting their effectiveness. Composite wick structures, combining two or more wicks such as sintered powder, mesh, grooves, and spiral woven mesh (SWM), have received significant attention for facilitating an optimised balance between these conflicting properties. Despite this growing research on composite wicks, no review has analysed their advancement and influence on heat pipe performance in comprehensive detail. Addressing this gap, the present work systematically reviews the performance of composite wick designs in cylindrical, flat, and looped heat pipes, with a focus on hydrodynamic and thermal performance characteristics such as permeability, thermal resistance, and heat transport capacity. Studies show that composite wicks can achieve up to 56 % higher performance and thermal resistances as low as 0.02 K/W for some cases. The review also underlines how operating conditions such as fluid charge ratio, orientation, and heat input affect the thermal performance of heat pipes with composite wicks. By synthesising key insights from different studies, this study provides a thorough assessment on the design and fabrication of composite wick-based heat pipes. The findings underscore the critical role of composite wicks in advancing next-generation thermal management systems and shaping future directions for scalable and highly effective heat pipe devices.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"256 ","pages":"Article 128130"},"PeriodicalIF":5.8,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145619953","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 : 2025-11-27DOI: 10.1016/j.ijheatmasstransfer.2025.128185
Ali Al-Masri , Khalil Khanafer
Efficient thermal management is a critical challenge in the design of modern electronic devices, where compact geometries and high heat fluxes demand advanced materials and simulation strategies. This study addresses this challenge by investigating phase change material (PCM)-filled aluminum honeycomb structures as a promising solution for passive thermal regulation in electronics. A multi-scale modeling framework is developed, coupling a representative volume element (RVE) with sub-modeling techniques to evaluate and improve the thermal behavior of these composite systems. Finite element-based RVE simulations are employed to derive homogenized, temperature-dependent thermal properties—including orthotropic thermal conductivity, density, and specific heat—capturing the macroscopic heat transfer characteristics of the structure. The model incorporates nonlinear material behavior and latent heat effects under transient thermal conditions with time-dependent Dirichlet boundary conditions. The homogenized panel model consisting of multiple unit cells completes its simulation within a few hours, whereas the refined RVE submodel requires a shorter runtime. In contrast, a fully detailed representation of the entire panel would contain several million elements, making direct simulation computationally impractical.
The homogenized model effectively predicts global thermal behavior, including temperature evolution and charging/discharging cycles. To resolve localized thermal gradients driven by PCM distribution, an embedded sub-modeling strategy enhances local accuracy without sacrificing efficiency. This coupled modeling approach is particularly well-suited for the design and enhancement of thermal management systems in electronic devices. It offers reduced computational time, scalability, and adaptability—enabling rapid, accurate simulations for parametric studies and real-time evaluations in applications such as power electronics, data centers, and portable consumer devices.
{"title":"Multi-scale thermal homogenization of PCM-filled aluminum honeycomb structures for electronic device thermal management","authors":"Ali Al-Masri , Khalil Khanafer","doi":"10.1016/j.ijheatmasstransfer.2025.128185","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128185","url":null,"abstract":"<div><div>Efficient thermal management is a critical challenge in the design of modern electronic devices, where compact geometries and high heat fluxes demand advanced materials and simulation strategies. This study addresses this challenge by investigating phase change material (PCM)-filled aluminum honeycomb structures as a promising solution for passive thermal regulation in electronics. A multi-scale modeling framework is developed, coupling a representative volume element (RVE) with sub-modeling techniques to evaluate and improve the thermal behavior of these composite systems. Finite element-based RVE simulations are employed to derive homogenized, temperature-dependent thermal properties—including orthotropic thermal conductivity, density, and specific heat—capturing the macroscopic heat transfer characteristics of the structure. The model incorporates nonlinear material behavior and latent heat effects under transient thermal conditions with time-dependent Dirichlet boundary conditions. The homogenized panel model consisting of multiple unit cells completes its simulation within a few hours, whereas the refined RVE submodel requires a shorter runtime. In contrast, a fully detailed representation of the entire panel would contain several million elements, making direct simulation computationally impractical.</div><div>The homogenized model effectively predicts global thermal behavior, including temperature evolution and charging/discharging cycles. To resolve localized thermal gradients driven by PCM distribution, an embedded sub-modeling strategy enhances local accuracy without sacrificing efficiency. This coupled modeling approach is particularly well-suited for the design and enhancement of thermal management systems in electronic devices. It offers reduced computational time, scalability, and adaptability—enabling rapid, accurate simulations for parametric studies and real-time evaluations in applications such as power electronics, data centers, and portable consumer devices.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"256 ","pages":"Article 128185"},"PeriodicalIF":5.8,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620430","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}
Identifying environmentally friendly refrigerants and understanding their two-phase heat transfer behavior has garnered significant attention, especially with the adoption of highly efficient plate heat exchangers (PHXs). In this study, R290 and two R290-based mixtures—HCM-01 (65% R290 and 35% R1270 by mass) and HYM-01 (35% R290 and 65% R13I1 by mass)—were evaluated as alternatives to R1234yf. Their comparative condensation behavior was analyzed in offset strip PHXs. During the experiments, vapor quality (ranging from 0.2 to 0.9) and mass flux (40–50 kg/m²·s) were varied, while saturation temperature and heat flux were held constant at 45 °C and 6 kW/m², respectively. Initially, condensation mechanisms and flow pattern mapping were conducted using established correlations, revealing forced convective condensation dominance for all refrigerants. However, the transition from bubbly to film flow occurred earlier for R1234yf and HYM-01 (at vapor quality > 0.3–0.4), whereas it was delayed for R290 and HCM-01. Moreover, the peak heat transfer coefficients of R290 and HCM-01 were 25.71–96.73% and 32.03–137.05% higher than that of R1234yf, respectively, while HYM-01 exhibited values 1.81–24.91% lower. On the other hand, R1234yf exhibited significantly lower frictional pressure drops—56.31% and 46.26% lower than R290 and HCM-01, respectively—at higher vapor quality regions. Performance indicators, namely condenser effectiveness and energy performance index (EPI), showed that R1234yf provided superior energy performance, while HCM-01 demonstrated the highest effectiveness. According to the exergy analysis, average exergy destruction in the condenser of R290, HCM-01, and HYM-01 were 1.91%, 1.05%, and 11.02% lower than R1234yf respectively at higher mass fluxes. Finally, a multi-criteria decision-making method was employed to identify the best alternative. Results indicated that assigning the highest weight to the heat transfer coefficient led to the maximum condensation performance index of 0.8497, with HCM-01 emerging as the optimal choice.
{"title":"Downward condensation of low-GWP refrigerants in a plate heat exchanger: Thermo-hydraulic-exergy analysis and multi-criteria decision-making optimization","authors":"Rajendran Prabakaran, Palanisamy Dhamodharan, Anbalagan Sathishkumar, Ramasamy Dhivagar, Sung Chul Kim","doi":"10.1016/j.ijheatmasstransfer.2025.128174","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128174","url":null,"abstract":"<div><div>Identifying environmentally friendly refrigerants and understanding their two-phase heat transfer behavior has garnered significant attention, especially with the adoption of highly efficient plate heat exchangers (PHXs). In this study, R290 and two R290-based mixtures—HCM-01 (65% R290 and 35% R1270 by mass) and HYM-01 (35% R290 and 65% R13I1 by mass)—were evaluated as alternatives to R1234yf. Their comparative condensation behavior was analyzed in offset strip PHXs. During the experiments, vapor quality (ranging from 0.2 to 0.9) and mass flux (40–50 kg/m²·s) were varied, while saturation temperature and heat flux were held constant at 45 °C and 6 kW/m², respectively. Initially, condensation mechanisms and flow pattern mapping were conducted using established correlations, revealing forced convective condensation dominance for all refrigerants. However, the transition from bubbly to film flow occurred earlier for R1234yf and HYM-01 (at vapor quality > 0.3–0.4), whereas it was delayed for R290 and HCM-01. Moreover, the peak heat transfer coefficients of R290 and HCM-01 were 25.71–96.73% and 32.03–137.05% higher than that of R1234yf, respectively, while HYM-01 exhibited values 1.81–24.91% lower. On the other hand, R1234yf exhibited significantly lower frictional pressure drops—56.31% and 46.26% lower than R290 and HCM-01, respectively—at higher vapor quality regions. Performance indicators, namely condenser effectiveness and energy performance index (EPI), showed that R1234yf provided superior energy performance, while HCM-01 demonstrated the highest effectiveness. According to the exergy analysis, average exergy destruction in the condenser of R290, HCM-01, and HYM-01 were 1.91%, 1.05%, and 11.02% lower than R1234yf respectively at higher mass fluxes. Finally, a multi-criteria decision-making method was employed to identify the best alternative. Results indicated that assigning the highest weight to the heat transfer coefficient led to the maximum condensation performance index of 0.8497, with HCM-01 emerging as the optimal choice.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"256 ","pages":"Article 128174"},"PeriodicalIF":5.8,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620754","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 : 2025-11-27DOI: 10.1016/j.ijheatmasstransfer.2025.128133
Qinhong Chen , Jingzhi Zhou , Jieni Wang , Kai Zhang , Xunfeng Li , Xiulan Huai
Jet impingement boiling cooling technology has shown exceptional promise for thermal management in high-power, high-performance electronic devices, owing to its superior heat transfer efficiency and rapid heat dissipation. This review systematically synthesizes the fundamental principles of jet impingement boiling and critically evaluates the influence mechanisms of key system parameters on thermal performance. Drawing upon over three decades of research, the analysis spans a wide range of working fluids, operating conditions, and geometric configurations. Special attention is given to the synergistic interactions among jet configurations, fluid properties, bubble dynamics, surface conditions, and gravitational effects, particularly in terms of their combined impact on critical heat flux (CHF), heat transfer coefficient (HTC), pressure drop, and temperature uniformity. Furthermore, various heat transfer enhancement strategies—such as surface modifications, nanofluids, hybrid jets and effusion structures—are comparatively analyzed to elucidate their underlying mechanisms and optimization potential. This review aims to provide theoretical insights for the design of advanced thermal management systems in ultra-high heat flux applications, including high-performance microprocessors, laser systems, and energy conversion devices.
{"title":"Review of jet impingement boiling heat transfer: mechanisms, influencing parameters and enhancement strategies","authors":"Qinhong Chen , Jingzhi Zhou , Jieni Wang , Kai Zhang , Xunfeng Li , Xiulan Huai","doi":"10.1016/j.ijheatmasstransfer.2025.128133","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.128133","url":null,"abstract":"<div><div>Jet impingement boiling cooling technology has shown exceptional promise for thermal management in high-power, high-performance electronic devices, owing to its superior heat transfer efficiency and rapid heat dissipation. This review systematically synthesizes the fundamental principles of jet impingement boiling and critically evaluates the influence mechanisms of key system parameters on thermal performance. Drawing upon over three decades of research, the analysis spans a wide range of working fluids, operating conditions, and geometric configurations. Special attention is given to the synergistic interactions among jet configurations, fluid properties, bubble dynamics, surface conditions, and gravitational effects, particularly in terms of their combined impact on critical heat flux (CHF), heat transfer coefficient (HTC), pressure drop, and temperature uniformity. Furthermore, various heat transfer enhancement strategies—such as surface modifications, nanofluids, hybrid jets and effusion structures—are comparatively analyzed to elucidate their underlying mechanisms and optimization potential. This review aims to provide theoretical insights for the design of advanced thermal management systems in ultra-high heat flux applications, including high-performance microprocessors, laser systems, and energy conversion devices.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"256 ","pages":"Article 128133"},"PeriodicalIF":5.8,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620752","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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