Pub Date : 2026-03-01Epub Date: 2025-12-19DOI: 10.1016/j.icheatmasstransfer.2025.110311
En-Chia Liu , Jie-Hau Liao , Heng-Chieh Chien , Jui-Cheng Yu , Chao-Yang Chiang , Po-Hsun He , Hsuan-Chi Weng , Ming-Ji Dai , Chien-Neng Liao
Nucleate pool boiling is highly effective for cooling high-power electronic devices and microsystems. In this work, a superhydrophilic dendritic-bush-shaped coating was electrodeposited on Cu substrates as boiling enhancement structures (BES). By varying H2SO4 and H3BO3 concentrations in the electrolyte, porous Cu films with different thicknesses and morphologies were obtained. Pool boiling experiments measured the critical heat flux (CHF) and heat transfer coefficient (HTC), while a contact angle analyzer and capillary rise tests evaluated the wettability and wicking properties. A distinct boiling inversion phenomenon was observed for porous Cu films with optimized structural parameters. High-speed imaging of bubble nucleation, growth, and departure revealed the link between surface architecture, bubble dynamics, and heat transfer performance. The optimized dendritic Cu structure achieved a CHF of 216 W/cm2 and an HTC of 24.6 W/cm2K, corresponding to enhancements of 125 % and 473 % over flat Cu. These findings highlight the promise of electrodeposited dendritic-bush structures for heat dissipation enhancement through nucleate pool boiling.
{"title":"Boiling inversion induced heat transfer enhancement of copper heat-spreaders with electrodeposited dendritic-bush structures","authors":"En-Chia Liu , Jie-Hau Liao , Heng-Chieh Chien , Jui-Cheng Yu , Chao-Yang Chiang , Po-Hsun He , Hsuan-Chi Weng , Ming-Ji Dai , Chien-Neng Liao","doi":"10.1016/j.icheatmasstransfer.2025.110311","DOIUrl":"10.1016/j.icheatmasstransfer.2025.110311","url":null,"abstract":"<div><div>Nucleate pool boiling is highly effective for cooling high-power electronic devices and microsystems. In this work, a superhydrophilic dendritic-bush-shaped coating was electrodeposited on Cu substrates as boiling enhancement structures (BES). By varying H<sub>2</sub>SO<sub>4</sub> and H<sub>3</sub>BO<sub>3</sub> concentrations in the electrolyte, porous Cu films with different thicknesses and morphologies were obtained. Pool boiling experiments measured the critical heat flux (CHF) and heat transfer coefficient (HTC), while a contact angle analyzer and capillary rise tests evaluated the wettability and wicking properties. A distinct boiling inversion phenomenon was observed for porous Cu films with optimized structural parameters. High-speed imaging of bubble nucleation, growth, and departure revealed the link between surface architecture, bubble dynamics, and heat transfer performance. The optimized dendritic Cu structure achieved a CHF of 216 W/cm<sup>2</sup> and an HTC of 24.6 W/cm<sup>2</sup>K, corresponding to enhancements of 125 % and 473 % over flat Cu. These findings highlight the promise of electrodeposited dendritic-bush structures for heat dissipation enhancement through nucleate pool boiling.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"172 ","pages":"Article 110311"},"PeriodicalIF":6.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797987","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 : 2026-03-01Epub Date: 2025-12-07DOI: 10.1016/j.icheatmasstransfer.2025.110245
Qin Ni, Bingqing Liu , Xiang Ling
Building on prior research on spray cooling with vapor–liquid separation structures, this study examines ethanol additives at varying concentrations and their effect on heat transfer across three surfaces (S1, S2, S3) with different copper mesh coverage, using theoretical modeling and experiments. S1 consists of only micropillars, S2 is a semi-micromesh surface that retains part of the mesh for capillary pumping while leaving micropillars exposed for droplet impact and vapor escape, and S3 is a fully-micromesh surface.
Capillary liquid supply is modeled with Darcy's law, while evaporation in the porous medium incorporates diffusion and Stefan convection. A mathematical model describes wicking and evaporation, showing that capillary uptake decreases with microfilm thickness and ethanol concentration. With DI water, initial uptake velocity reaches 150.4 m/s—about 181 times higher than through full-layer penetration and 5.4 times higher than with 60 % ethanol solution. During early phase-change heat transfer, evaporation rate falls with heat flux; when it nears zero, boiling dominates, suggesting a predictor of critical heat flux. Heat transfer curves reveal performance improves with greater mesh coverage. On the fully-micromesh surface, DI water achieves the best results, with maximum heat flux reaching 821.4 W/cm2 due to higher uptake rates and latent heat.
{"title":"Study on spray cooling heat transfer enhancement mechanisms based on capillary imbibition and evaporation models","authors":"Qin Ni, Bingqing Liu , Xiang Ling","doi":"10.1016/j.icheatmasstransfer.2025.110245","DOIUrl":"10.1016/j.icheatmasstransfer.2025.110245","url":null,"abstract":"<div><div>Building on prior research on spray cooling with vapor–liquid separation structures, this study examines ethanol additives at varying concentrations and their effect on heat transfer across three surfaces (S1, S2, S3) with different copper mesh coverage, using theoretical modeling and experiments. S1 consists of only micropillars, S2 is a semi-micromesh surface that retains part of the mesh for capillary pumping while leaving micropillars exposed for droplet impact and vapor escape, and S3 is a fully-micromesh surface.</div><div>Capillary liquid supply is modeled with Darcy's law, while evaporation in the porous medium incorporates diffusion and Stefan convection. A mathematical model describes wicking and evaporation, showing that capillary uptake decreases with microfilm thickness and ethanol concentration. With DI water, initial uptake velocity reaches 150.4 m/s—about 181 times higher than through full-layer penetration and 5.4 times higher than with 60 % ethanol solution. During early phase-change heat transfer, evaporation rate falls with heat flux; when it nears zero, boiling dominates, suggesting a predictor of critical heat flux. Heat transfer curves reveal performance improves with greater mesh coverage. On the fully-micromesh surface, DI water achieves the best results, with maximum heat flux reaching 821.4 W/cm<sup>2</sup> due to higher uptake rates and latent heat.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"172 ","pages":"Article 110245"},"PeriodicalIF":6.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734190","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 : 2026-03-01Epub Date: 2025-12-09DOI: 10.1016/j.icheatmasstransfer.2025.110248
Walid Aich , Ramadan Youssef Sakr , Ali Basem , As'ad Alizadeh , Mazen M. Othayq , Mujtaba A. Flayyih , Wajdi Rajhi , Khalil Hajlaoui
This study aims to improve thermal management in small, high-power devices by numerically analyzing water-cooled micro-pin-fin heat sinks with novel geometries. Under various Reynolds numbers, the impacts of the proposed fin geometry and diameter ratio were systematically assessed using computational fluid dynamics (CFD). The trade-off between cooling enhancement and hydraulic losses was evaluated by analyzing key performance indicators, including average Nusselt number, wall temperature, pressure drop, thermal energy absorption, heat transfer coefficient, and thermal performance factor. The concave pin-fin configuration (Case A) outperformed traditional cylindrical fins in the first section, improving thermal performance of almost 8 % at Re = 500 and 7 % at Re = 2000. The impact of the diameter ratio was examined in the second section. The biggest ratio (DR = 1.00) produced the best results, with efficiency gains of roughly 6 % at Re = 500 and 5 % at Re = 2000 compared to the lowest ratio (DR = 0.25). All things considered, the results demonstrate that novel pin-fin designs and adjusted diameter ratios deliver notable and reliable increases in thermal efficiency across a broad range of flow conditions, making them attractive options for cutting-edge liquid-cooling applications.
{"title":"Numerical assessment and design of advanced micro pin-fin heat sink configurations: Augmented water cooling solutions","authors":"Walid Aich , Ramadan Youssef Sakr , Ali Basem , As'ad Alizadeh , Mazen M. Othayq , Mujtaba A. Flayyih , Wajdi Rajhi , Khalil Hajlaoui","doi":"10.1016/j.icheatmasstransfer.2025.110248","DOIUrl":"10.1016/j.icheatmasstransfer.2025.110248","url":null,"abstract":"<div><div>This study aims to improve thermal management in small, high-power devices by numerically analyzing water-cooled micro-pin-fin heat sinks with novel geometries. Under various Reynolds numbers, the impacts of the proposed fin geometry and diameter ratio were systematically assessed using computational fluid dynamics (CFD). The trade-off between cooling enhancement and hydraulic losses was evaluated by analyzing key performance indicators, including average Nusselt number, wall temperature, pressure drop, thermal energy absorption, heat transfer coefficient, and thermal performance factor. The concave pin-fin configuration (Case A) outperformed traditional cylindrical fins in the first section, improving thermal performance of almost 8 % at <em>Re</em> = 500 and 7 % at <em>Re</em> = 2000. The impact of the diameter ratio was examined in the second section. The biggest ratio (DR = 1.00) produced the best results, with efficiency gains of roughly 6 % at <em>Re</em> = 500 and 5 % at <em>Re</em> = 2000 compared to the lowest ratio (DR = 0.25). All things considered, the results demonstrate that novel pin-fin designs and adjusted diameter ratios deliver notable and reliable increases in thermal efficiency across a broad range of flow conditions, making them attractive options for cutting-edge liquid-cooling applications.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"172 ","pages":"Article 110248"},"PeriodicalIF":6.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734191","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 : 2026-03-01Epub Date: 2025-12-09DOI: 10.1016/j.icheatmasstransfer.2025.110230
Qi Xie , Xinyu Mao , Lin Ruan , De Lu , Liang Ji , Hu Zhang
The thermal radiation properties of ZrB2-SiC ceramic composites are vital for thermal transport applications, such as thermal protection system of aircraft. The optical constants of ZrB2 and α-SiC were experimentally determined via spectroscopic ellipsometry across 0.2–20 μm wavelengths from 25 °C to 600 °C. A finite-difference time-domain (FDTD) framework was established to quantify the influences of material thickness (0.5 to 6 μm), temperature (25 to 600 °C), SiC particle shape (sphere, whisker, platelet), SiC volume fraction (20 % to 50 %), SiC particle diameter (1 to 4 μm), surface roughness (Ra, 0 to 1 μm) and porosity (5 % to 15 %) on the spectral emissivity within 1–20 μm. Additionally, the effects of above factors on the average emissivity within the atmospheric windows were compared to assess infrared stealth performance of the composites. The results indicate that the emissivity of ZrB2-SiC composites increases with the increments of temperature, surface roughness, porosity, SiC volume fraction, and particle diameter and decreases with the increment of the surface-area-to-volume ratio of SiC particle and material thickness. These factors can induce a variation of 83.9 %, 41.5 %, 12.3 %, 136.1 %, 75.6 %, 74.9 %, and 9.7 % in the total emissivity, respectively. This research offers promising insights for guiding the regulation of spectral radiative characteristics of ZrB2-SiC ceramic composites and enhancing the infrared stealth performance.
{"title":"Numerical study on the infrared radiative properties of ZrB2-SiC ceramic composites","authors":"Qi Xie , Xinyu Mao , Lin Ruan , De Lu , Liang Ji , Hu Zhang","doi":"10.1016/j.icheatmasstransfer.2025.110230","DOIUrl":"10.1016/j.icheatmasstransfer.2025.110230","url":null,"abstract":"<div><div>The thermal radiation properties of ZrB<sub>2</sub>-SiC ceramic composites are vital for thermal transport applications, such as thermal protection system of aircraft. The optical constants of ZrB<sub>2</sub> and <em>α</em>-SiC were experimentally determined via spectroscopic ellipsometry across 0.2–20 μm wavelengths from 25 °C to 600 °C. A finite-difference time-domain (FDTD) framework was established to quantify the influences of material thickness (0.5 to 6 μm), temperature (25 to 600 °C), SiC particle shape (sphere, whisker, platelet), SiC volume fraction (20 % to 50 %), SiC particle diameter (1 to 4 μm), surface roughness (<em>R</em><sub><em>a</em></sub>, 0 to 1 μm) and porosity (5 % to 15 %) on the spectral emissivity within 1–20 μm. Additionally, the effects of above factors on the average emissivity within the atmospheric windows were compared to assess infrared stealth performance of the composites. The results indicate that the emissivity of ZrB<sub>2</sub>-SiC composites increases with the increments of temperature, surface roughness, porosity, SiC volume fraction, and particle diameter and decreases with the increment of the surface-area-to-volume ratio of SiC particle and material thickness. These factors can induce a variation of 83.9 %, 41.5 %, 12.3 %, 136.1 %, 75.6 %, 74.9 %, and 9.7 % in the total emissivity, respectively. This research offers promising insights for guiding the regulation of spectral radiative characteristics of ZrB<sub>2</sub>-SiC ceramic composites and enhancing the infrared stealth performance.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"172 ","pages":"Article 110230"},"PeriodicalIF":6.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734348","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 : 2026-03-01Epub Date: 2026-01-22DOI: 10.1016/j.icheatmasstransfer.2026.110581
Peng Pan , Kai-Xin Di , Li-Ke Niu
Despite their widespread application in heat exchange systems, vortex tubes were limited by their inadequate cooling and heating efficiency. Hence, the novel helical internals were designed and integrated into the vortex tube to enhance its performance. The characteristics of temperature separation in an innovative vortex tube were assessed employing numerical methods, and results indicated that under an inlet mass flow rate of 0.004 kg/s and a cold mass fraction ranging from 0.1 to 0.9, the cooling effect was further increased by 4.93 K, while the heating effect was improved by 1.68 K, compared to conventional vortex tubes. The performance enhancement was attributed to the effective flow field regulation achieved through the introduction of helical internals. Additionally, a highly accurate predictive model was developed based on regression analysis, which provided a reliable tool for the engineering application of vortex tube technology.
{"title":"Numerical investigation on the performance enhancement of vortex tubes incorporating innovative helical internals","authors":"Peng Pan , Kai-Xin Di , Li-Ke Niu","doi":"10.1016/j.icheatmasstransfer.2026.110581","DOIUrl":"10.1016/j.icheatmasstransfer.2026.110581","url":null,"abstract":"<div><div>Despite their widespread application in heat exchange systems, vortex tubes were limited by their inadequate cooling and heating efficiency. Hence, the novel helical internals were designed and integrated into the vortex tube to enhance its performance. The characteristics of temperature separation in an innovative vortex tube were assessed employing numerical methods, and results indicated that under an inlet mass flow rate of 0.004 kg/s and a cold mass fraction ranging from 0.1 to 0.9, the cooling effect was further increased by 4.93 K, while the heating effect was improved by 1.68 K, compared to conventional vortex tubes. The performance enhancement was attributed to the effective flow field regulation achieved through the introduction of helical internals. Additionally, a highly accurate predictive model was developed based on regression analysis, which provided a reliable tool for the engineering application of vortex tube technology.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"172 ","pages":"Article 110581"},"PeriodicalIF":6.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146022402","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 : 2026-03-01Epub Date: 2026-01-22DOI: 10.1016/j.icheatmasstransfer.2026.110584
Shili Lin, Mingbiao Chen
Deep understanding of ice nucleation in supercooled water is crucial for advancing technologies such as anti-icing of airplanes, ice making of supercooled water and organ preservation. However, the combined effects of both shear and temperature gradient in the near-wall region are frequently overlooked, leading to significant discrepancies in predictions and a severe effect on the application of the technologies. Here, we proposed an ice nucleation model considering the rebounded deformation energy and temperature gradient to analyze the ice nucleation in the near-wall region. It was found that: (1) The critical nucleus radius is the central parameter through which shear rate and temperature gradient exhibit competitive interplay. (2) The competition creates a scale effect that regulates nucleation sensitivity. A larger critical nucleus radius amplifies the nucleus's perception of the temperature gradient. (3) Compared to the thermodynamic term ratio, the nucleation rate ratio followed a similar trend in response to changes in temperature gradient.
{"title":"Ice nucleation of supercooled water in the near-wall region","authors":"Shili Lin, Mingbiao Chen","doi":"10.1016/j.icheatmasstransfer.2026.110584","DOIUrl":"10.1016/j.icheatmasstransfer.2026.110584","url":null,"abstract":"<div><div>Deep understanding of ice nucleation in supercooled water is crucial for advancing technologies such as anti-icing of airplanes, ice making of supercooled water and organ preservation. However, the combined effects of both shear and temperature gradient in the near-wall region are frequently overlooked, leading to significant discrepancies in predictions and a severe effect on the application of the technologies. Here, we proposed an ice nucleation model considering the rebounded deformation energy and temperature gradient to analyze the ice nucleation in the near-wall region. It was found that: (1) The critical nucleus radius is the central parameter through which shear rate and temperature gradient exhibit competitive interplay. (2) The competition creates a scale effect that regulates nucleation sensitivity. A larger critical nucleus radius amplifies the nucleus's perception of the temperature gradient. (3) Compared to the thermodynamic term ratio, the nucleation rate ratio followed a similar trend in response to changes in temperature gradient.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"172 ","pages":"Article 110584"},"PeriodicalIF":6.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146022401","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 : 2026-03-01Epub Date: 2026-01-30DOI: 10.1016/j.icheatmasstransfer.2026.110624
Yao Yang , Zaoyang Li , Junlan Wang , ChongChong Qi , Guanghui Wu , Quanzhi Wang , Lijun Liu , Tao Wang , Yiqi Peng , Dongli Hu
Induction heating is commonly used in the top-seeded solution growth (TSSG) of SiC crystals to provide heating power and at the same time generates Lorentz force in the solution, namely the thermal effect and the magnetic effect. Therefore, studying the thermal-magnetic effects is critical to minimize the system power consumption and improve the crystal growth simultaneously. In this study, a global numerical model was established to calculate the induction heating, heat transfer, solution flow and carbon transport in the SiC crystal growth by TSSG method. The combined thermal-magnetic effects were systematically studied to find out optimal heating parameters that can simultaneously utilize both effects. The results indicate that excessively high or low frequencies increase the total heating power consumption and reduce the induction heating efficiency. The optimal frequency range is 1–2 kHz in this study, for which the minimum total power consumption is 34.4 kW and the maximum heating efficiency is 82.0%. The Lorentz force in the solution changes significantly with the increase of frequency, and thus influences the crystal growth parameters. It's found that the growth rate is relatively high and uniform at 1–2 kHz. Therefore, the thermal-magnetic effects can be utilized simultaneously to optimize the SiC crystal growth.
{"title":"Thermal-magnetic effects in the SiC crystal growth by top-seeded solution growth method with induction heating","authors":"Yao Yang , Zaoyang Li , Junlan Wang , ChongChong Qi , Guanghui Wu , Quanzhi Wang , Lijun Liu , Tao Wang , Yiqi Peng , Dongli Hu","doi":"10.1016/j.icheatmasstransfer.2026.110624","DOIUrl":"10.1016/j.icheatmasstransfer.2026.110624","url":null,"abstract":"<div><div>Induction heating is commonly used in the top-seeded solution growth (TSSG) of SiC crystals to provide heating power and at the same time generates Lorentz force in the solution, namely the thermal effect and the magnetic effect. Therefore, studying the thermal-magnetic effects is critical to minimize the system power consumption and improve the crystal growth simultaneously. In this study, a global numerical model was established to calculate the induction heating, heat transfer, solution flow and carbon transport in the SiC crystal growth by TSSG method. The combined thermal-magnetic effects were systematically studied to find out optimal heating parameters that can simultaneously utilize both effects. The results indicate that excessively high or low frequencies increase the total heating power consumption and reduce the induction heating efficiency. The optimal frequency range is 1–2 kHz in this study, for which the minimum total power consumption is 34.4 kW and the maximum heating efficiency is 82.0%. The Lorentz force in the solution changes significantly with the increase of frequency, and thus influences the crystal growth parameters. It's found that the growth rate is relatively high and uniform at 1–2 kHz. Therefore, the thermal-magnetic effects can be utilized simultaneously to optimize the SiC crystal growth.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"172 ","pages":"Article 110624"},"PeriodicalIF":6.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073834","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 : 2026-03-01Epub Date: 2026-01-27DOI: 10.1016/j.icheatmasstransfer.2026.110572
Linzhi Yin , Xin Sun , Hesam Naseri , S. Mohammad Sajadi , Mustafa Bayram , Majed M. Alghamdi
This study uniquely investigated the impact of nitrogen doping on the mechanical stability, structural deformation, and energetic properties of carbon nanotubes (CNTs) through non-equilibrium molecular dynamics simulations, systematically varying nitrogen doping concentrations (5%, 10%, 15%, 20%, 25%, and 30%). Unlike prior studies that mainly focused on electronic or catalytic effects, this work provides new atomic-level insights into how nitrogen doping alters the mechanical response of CNTs during buckling. We analyzed the evolution of kinetic energy, potential energy, the center of mass (COM), mean-squared displacement (MSD), and interaction energy throughout the simulations. Our results demonstrate that increased nitrogen doping led to higher atomic mobility and structural disorder, as indicated by elevated kinetic energy and MSD values both before and after buckling. The potential energy profiles showed that nitrogen-rich nanotubes adopted lower-energy configurations, reflecting diminished structural stability. COM analysis revealed that higher doping levels hindered global structural shifts during deformation, indicating that buckling occurred through localized, severe kinks rather than uniform bending. Contrary to expectations, interaction energy remained largely unaffected by nitrogen doping, suggesting that doping primarily affected structural dynamics rather than atomic interaction energy. These findings confirmed that nitrogen doping destabilized the CNT structure, increasing susceptibility to mechanical deformation. This comprehensive exploration of mechanical and dynamic effects distinguished our work, offering critical insights for designing nitrogen-doped CNTs in nanotechnology applications where mechanical integrity is pivotal.
{"title":"Investigating the effect of nitrogen doping on the buckling process of carbon nanotubes using non-equilibrium molecular dynamics simulation","authors":"Linzhi Yin , Xin Sun , Hesam Naseri , S. Mohammad Sajadi , Mustafa Bayram , Majed M. Alghamdi","doi":"10.1016/j.icheatmasstransfer.2026.110572","DOIUrl":"10.1016/j.icheatmasstransfer.2026.110572","url":null,"abstract":"<div><div>This study uniquely investigated the impact of nitrogen doping on the mechanical stability, structural deformation, and energetic properties of carbon nanotubes (CNTs) through non-equilibrium molecular dynamics simulations, systematically varying nitrogen doping concentrations (5%, 10%, 15%, 20%, 25%, and 30%). Unlike prior studies that mainly focused on electronic or catalytic effects, this work provides new atomic-level insights into how nitrogen doping alters the mechanical response of CNTs during buckling. We analyzed the evolution of kinetic energy, potential energy, the center of mass (COM), mean-squared displacement (MSD), and interaction energy throughout the simulations. Our results demonstrate that increased nitrogen doping led to higher atomic mobility and structural disorder, as indicated by elevated kinetic energy and MSD values both before and after buckling. The potential energy profiles showed that nitrogen-rich nanotubes adopted lower-energy configurations, reflecting diminished structural stability. COM analysis revealed that higher doping levels hindered global structural shifts during deformation, indicating that buckling occurred through localized, severe kinks rather than uniform bending. Contrary to expectations, interaction energy remained largely unaffected by nitrogen doping, suggesting that doping primarily affected structural dynamics rather than atomic interaction energy. These findings confirmed that nitrogen doping destabilized the CNT structure, increasing susceptibility to mechanical deformation. This comprehensive exploration of mechanical and dynamic effects distinguished our work, offering critical insights for designing nitrogen-doped CNTs in nanotechnology applications where mechanical integrity is pivotal.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"172 ","pages":"Article 110572"},"PeriodicalIF":6.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073835","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 : 2026-03-01Epub Date: 2026-01-28DOI: 10.1016/j.icheatmasstransfer.2026.110645
Buse Nur Alyaz, Mehmet Sorgun
Accurately estimating turbulent flow behavior for Newtonian and non-Newtonian fluids is crucial for optimizing energy efficiency and the design of industrial pipeline systems. This study investigates the mean velocity profiles and wall shear stress of turbulent pipe flows to improve the reliability of flow predictions for practical engineering applications. Extensive experimental work was conducted at the Izmir Katip Celebi University flow loop, using xanthan gum (XG) and partially hydrolyzed polyacrylamide (PHPA) solutions used exensively in petroleum and chemical industries, covering a Reynolds number range of 4 × 103 to 3.2 × 104. The Herschel–Bulkley model was identified as the most suitable rheological model for describing the flow behavior of XG and PHPA solutions. Numerical simulations based on two widely used computational approaches such as the finite element method (FEM) and the finite volume method (FVM) were employed to solve the governing flow equations, and their predictions were systematically compared with experimental measurements for both smooth and rough pipe surfaces. The results demonstrate that the numerical models predict wall shear stress and velocity distributions with significantly improved accuracy compared to commonly used empirical correlations, particularly for shear-thinning fluids. Increased wall roughness reduced near-wall velocities and shifted the mean velocity profile, while stronger shear thinning caused significant deviations from Newtonian turbulent behavior. This work combines experimental and numerical analyses to overcome the limitations of traditional correlations, offering a more reliable framework for predicting turbulent non-Newtonian pipe flows.
{"title":"Mean velocity profiles and wall shear stress of Herschel–Bulkley fluids in pipe flow: CFD modeling and experimental validation","authors":"Buse Nur Alyaz, Mehmet Sorgun","doi":"10.1016/j.icheatmasstransfer.2026.110645","DOIUrl":"10.1016/j.icheatmasstransfer.2026.110645","url":null,"abstract":"<div><div>Accurately estimating turbulent flow behavior for Newtonian and non-Newtonian fluids is crucial for optimizing energy efficiency and the design of industrial pipeline systems. This study investigates the mean velocity profiles and wall shear stress of turbulent pipe flows to improve the reliability of flow predictions for practical engineering applications. Extensive experimental work was conducted at the Izmir Katip Celebi University flow loop, using xanthan gum (XG) and partially hydrolyzed polyacrylamide (PHPA) solutions used exensively in petroleum and chemical industries, covering a Reynolds number range of 4 × 10<sup>3</sup> to 3.2 × 10<sup>4</sup>. The Herschel–Bulkley model was identified as the most suitable rheological model for describing the flow behavior of XG and PHPA solutions. Numerical simulations based on two widely used computational approaches such as the finite element method (FEM) and the finite volume method (FVM) were employed to solve the governing flow equations, and their predictions were systematically compared with experimental measurements for both smooth and rough pipe surfaces. The results demonstrate that the numerical models predict wall shear stress and velocity distributions with significantly improved accuracy compared to commonly used empirical correlations, particularly for shear-thinning fluids. Increased wall roughness reduced near-wall velocities and shifted the mean velocity profile, while stronger shear thinning caused significant deviations from Newtonian turbulent behavior. This work combines experimental and numerical analyses to overcome the limitations of traditional correlations, offering a more reliable framework for predicting turbulent non-Newtonian pipe flows.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"172 ","pages":"Article 110645"},"PeriodicalIF":6.4,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146073843","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 : 2026-03-01Epub Date: 2026-01-29DOI: 10.1016/j.icheatmasstransfer.2026.110630
Fang Rao , Changjun Li , Caigong Zhang , Donghao Yang , Chao Chen
As a critical hydrogen carrier, ammonia is gaining increasing attention in the global energy transition and is primarily transported by pipeline in liquid form. If a leak occurs during pipeline operation, liquid ammonia will rapidly flash-vaporize as atmospheric pressure is considerably lower than the operating pressure, leading to a decrease in ambient temperature. The vaporized ammonia first permeates through the soil before overcoming surface resistance to diffuse into the air. This process not only endangers the safety of liquid ammonia transportation but also imposes severe environmental hazards. However, current research mainly focuses on the leakage and diffusion characteristics of liquid ammonia in air. Until now, the characteristics of liquid ammonia leakage, the phase change of liquid ammonia in porous soil, and the coupled diffusion in soil and air remain poorly understood. In this work, we develop a CFD model based on the Eulerian model, the porous media model, the Lee model, and the species transport model to reveal the leakage-phase change-diffusion characteristics. We comprehensively investigate the distribution of volume fraction, temperature, and pressure under pipeline operating pressure of 3.5 MPa, ambient temperature of 293.15 K, and a leak hole of 30 mm. Moreover, we discuss the effects of soil properties, wind speed, and ambient temperature on the leakage-phase change-diffusion characteristics. The results indicate that three distinct regions are formed after the liquid ammonia leakage: a liquid region near the leakage source, a transitional vaporization region in the soil, and a dense gas cloud dispersion region in the air. Temperature evolution involves an initial flash evaporation-dominated stage, followed by a dynamic equilibrium stage. Soil resistance is negatively correlated with both the diffusion rate into the air and the temperature drop rate. The wind speed mainly affects the diffusion pattern of vapor ammonia in the air. The minimum temperatures under different ambient temperatures eventually stabilize at similar steady-state values.
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