Pub Date : 2026-06-01Epub Date: 2026-03-12DOI: 10.1016/j.icheatmasstransfer.2026.110985
Yulong Zhao , Yucong Xiao , Yongjian Hou , Benxi Zhang , Shixue Wang , Minghui Ge
Coupling phase change materials (PCMs) with thermoelectric generators (TEGs) can mitigate the instability in output performance caused by fluctuations in heat sources. In this study, an experimental test system for PCM-TEG was established, and erythritol was selected as the phase change material. The impact of dynamic heat source parameters on the key performance parameters of the PCM-TEG system was investigated. The results indicate that compared with traditional thermoelectric generation systems (TTEGs), the PCM-TEG system reduced the hot end temperature by 48.6 °C, effectively preventing TEG from overheating damage. The maximum output voltage of the PCM-TEG system was only 85% of the TTEGs, but the operating time was extended by 43.1% compared with the TTEGs. At heat source powers of 40 W and 60 W, the PCM was unable to undergo phase transition, which was unfavorable for heat storage. Both the maximum output power and average efficiency of the system increased with the rise in heat source power. A longer heating time led to higher temperatures during the PCM heating phase, resulting in higher maximum output power. Increasing the heating time from 6000 s to 12,000 s led to a 47.1% enhancement in the maximum output power. Moreover, prolonging the heating time could extend the operating time of the high-voltage stage, albeit with minimal impact on the output performance during the PCM heat release phase.
{"title":"Experimental analysis of the dynamic performance of a phase change material-thermoelectric generator system","authors":"Yulong Zhao , Yucong Xiao , Yongjian Hou , Benxi Zhang , Shixue Wang , Minghui Ge","doi":"10.1016/j.icheatmasstransfer.2026.110985","DOIUrl":"10.1016/j.icheatmasstransfer.2026.110985","url":null,"abstract":"<div><div>Coupling phase change materials (PCMs) with thermoelectric generators (TEGs) can mitigate the instability in output performance caused by fluctuations in heat sources. In this study, an experimental test system for PCM-TEG was established, and erythritol was selected as the phase change material. The impact of dynamic heat source parameters on the key performance parameters of the PCM-TEG system was investigated. The results indicate that compared with traditional thermoelectric generation systems (TTEGs), the PCM-TEG system reduced the hot end temperature by 48.6 °C, effectively preventing TEG from overheating damage. The maximum output voltage of the PCM-TEG system was only 85% of the TTEGs, but the operating time was extended by 43.1% compared with the TTEGs. At heat source powers of 40 W and 60 W, the PCM was unable to undergo phase transition, which was unfavorable for heat storage. Both the maximum output power and average efficiency of the system increased with the rise in heat source power. A longer heating time led to higher temperatures during the PCM heating phase, resulting in higher maximum output power. Increasing the heating time from 6000 s to 12,000 s led to a 47.1% enhancement in the maximum output power. Moreover, prolonging the heating time could extend the operating time of the high-voltage stage, albeit with minimal impact on the output performance during the PCM heat release phase.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"175 ","pages":"Article 110985"},"PeriodicalIF":6.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388252","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 : 2026-06-01Epub Date: 2026-03-12DOI: 10.1016/j.icheatmasstransfer.2026.111024
Zhihan Fan , Hui Wang , Hongtao Hu , Qing Ren , Oleksandr Stelmakh , Hongyu Fu , Hao Zhang
This study extends the thermo-mixed elastohydrodynamic lubrication (TMEHL) model coupled with the GT contact model to investigate the lubrication behavior of packing in ultra-high-pressure ethylene compressors, and improves the lubrication model by refitting the relationship between asperity load and film thickness within the Greenwood–Tripp (GT) framework. The model explicitly incorporates the plunger's elastic modulus and surface roughness, addressing limitations of conventional approaches. Lubrication and thermal behavior are analyzed over the entire stroke, with emphasis on the effects of surface roughness and environmental temperature. Results indicate that hydrodynamic pressure peaks at the inlet zone and increases with sliding velocity, while asperity contact primarily occurs in regions of concentrated static contact pressure. The predicted film thickness ratio indicates that the interface predominantly operates under mixed lubrication, with minimum thickness and maximum friction at the end of compression. The average oil film temperature, influenced by sliding velocity and asperity contact pressure, reaches 416 K at a crank angle (CA) of 120°. Increasing surface roughness enhances asperity load support and raises lubricant temperature, while the initial improvement in film thickness ratio diminishes with roughness. Higher environmental temperatures reduce lubricant viscosity and fluid pressure, raising friction at high sliding velocities. Leakage is primarily governed by velocity, which is higher during the outstroke, with minimal influence of ambient temperature.
{"title":"Numerical investigation on lubrication of metal packing using an improved thermo-mixed elastohydrodynamic approach","authors":"Zhihan Fan , Hui Wang , Hongtao Hu , Qing Ren , Oleksandr Stelmakh , Hongyu Fu , Hao Zhang","doi":"10.1016/j.icheatmasstransfer.2026.111024","DOIUrl":"10.1016/j.icheatmasstransfer.2026.111024","url":null,"abstract":"<div><div>This study extends the thermo-mixed elastohydrodynamic lubrication (TMEHL) model coupled with the GT contact model to investigate the lubrication behavior of packing in ultra-high-pressure ethylene compressors, and improves the lubrication model by refitting the relationship between asperity load and film thickness within the Greenwood–Tripp (GT) framework. The model explicitly incorporates the plunger's elastic modulus and surface roughness, addressing limitations of conventional approaches. Lubrication and thermal behavior are analyzed over the entire stroke, with emphasis on the effects of surface roughness and environmental temperature. Results indicate that hydrodynamic pressure peaks at the inlet zone and increases with sliding velocity, while asperity contact primarily occurs in regions of concentrated static contact pressure. The predicted film thickness ratio indicates that the interface predominantly operates under mixed lubrication, with minimum thickness and maximum friction at the end of compression. The average oil film temperature, influenced by sliding velocity and asperity contact pressure, reaches 416 K at a crank angle (CA) of 120°. Increasing surface roughness enhances asperity load support and raises lubricant temperature, while the initial improvement in film thickness ratio diminishes with roughness. Higher environmental temperatures reduce lubricant viscosity and fluid pressure, raising friction at high sliding velocities. Leakage is primarily governed by velocity, which is higher during the outstroke, with minimal influence of ambient temperature.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"175 ","pages":"Article 111024"},"PeriodicalIF":6.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388253","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}
In this study, three engineered aluminum surfaces with distinct wettability characteristics, namely plain superhydrophobic, unidirectional wettability gradient, and patterned wettability, were fabricated and systematically evaluated for moist-air condensation under controlled conditions. The plain superhydrophobic surface was created by chemical etching and hot water treatment, then functionalized with 1H,1H,2H,2H-perfluorooctyl trichlorosilane. The wettability gradient surface was produced using a gradual substrate elevation method comprising chemical etching, hot water treatment, and trichlorosilane coating. A combination of chemical etching, hot-water treatment, masking, coating, and plasma etching produced the patterned surface. Surfaces were characterized using atomic force microscopy (AFM) for roughness, SEM for morphology, and FT-IR for chemistry. Wetting behaviour was assessed by measuring the equilibrium contact angle and hysteresis of a water droplet. Moist air condensation experiments were conducted at defined subcooling and relative humidity levels, and all quantitative results are reported as mean values with uncertainty based on the standard deviation. Surface performance was evaluated under orientation-matched, regime-specific conditions to isolate intrinsic wettability effects from gravitational drainage. The unidirectional wettability gradient surface exhibited a 36% higher condensation rate than a comparable superhydrophobic surface in the horizontal pendant (downward facing) configuration, whereas the patterned vertical surface had a 51% higher condensation rate than the plain vertical superhydrophobic surface under identical gravity assisted conditions. Results reveal that condensation depends on surface energy gradients and gravity. Wettability affects droplet transport differently in capillary and gravity regimes. Higher subcooling and humidity increase the rate of condensate collection. The work provides a framework for designing wettability to optimize droplet transport and water collection.
{"title":"Influence of wettability design on moist air condensation: Superhydrophobic, unidirectional wettability gradient and patterned surfaces","authors":"Smile Kataria , Basant Singh Sikarwar , Ranjit Kumar , K. Muralidhar","doi":"10.1016/j.icheatmasstransfer.2026.111017","DOIUrl":"10.1016/j.icheatmasstransfer.2026.111017","url":null,"abstract":"<div><div>In this study, three engineered aluminum surfaces with distinct wettability characteristics, namely plain superhydrophobic, unidirectional wettability gradient, and patterned wettability, were fabricated and systematically evaluated for moist-air condensation under controlled conditions. The plain superhydrophobic surface was created by chemical etching and hot water treatment, then functionalized with 1H,1H,2H,2H-perfluorooctyl trichlorosilane. The wettability gradient surface was produced using a gradual substrate elevation method comprising chemical etching, hot water treatment, and trichlorosilane coating. A combination of chemical etching, hot-water treatment, masking, coating, and plasma etching produced the patterned surface. Surfaces were characterized using atomic force microscopy (AFM) for roughness, SEM for morphology, and FT-IR for chemistry. Wetting behaviour was assessed by measuring the equilibrium contact angle and hysteresis of a water droplet. Moist air condensation experiments were conducted at defined subcooling and relative humidity levels, and all quantitative results are reported as mean values with uncertainty based on the standard deviation. Surface performance was evaluated under orientation-matched, regime-specific conditions to isolate intrinsic wettability effects from gravitational drainage. The unidirectional wettability gradient surface exhibited a 36% higher condensation rate than a comparable superhydrophobic surface in the horizontal pendant (downward facing) configuration, whereas the patterned vertical surface had a 51% higher condensation rate than the plain vertical superhydrophobic surface under identical gravity assisted conditions. Results reveal that condensation depends on surface energy gradients and gravity. Wettability affects droplet transport differently in capillary and gravity regimes. Higher subcooling and humidity increase the rate of condensate collection. The work provides a framework for designing wettability to optimize droplet transport and water collection.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"175 ","pages":"Article 111017"},"PeriodicalIF":6.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388239","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 : 2026-06-01Epub Date: 2026-03-11DOI: 10.1016/j.icheatmasstransfer.2026.110987
Gang Wang , Jiatai Lin , Zhenhua Quan , Wan Yu , Rongxin Zhu , Tao Hu , Huashan Su
Addressing the challenges of heat dissipation and non-uniform temperature distribution in low-heat-flux electronic devices, this study designed a U-shaped micro heat pipe heat sink by coupling a micro heat pipe array (MHPA) with fins and systematically analyzed its thermal performance. Experimental results show that under various input power conditions, the U-shaped MHPA at a 60° inclination exhibited superior startup performance and steady-state heat transfer capability. This performance, attributed to an optimal balance between working fluid evaporation and condensate return flow resistance, was significantly better than that at 30° and 90° inclinations. Regarding fin structure, the serrated fin demonstrated the best overall performance under both natural and forced convection, reducing the heat source temperature to 86.6 °C and 37.6 °C, respectively. When the airflow velocity reached 3 m/s, the decreasing trend of the steady-state temperature and thermal response time of the heat source slowed markedly, indicating limited additional benefit from further increasing airflow. Considering the cooling performance across different power inputs and airflow velocities, the U-shaped micro heat pipe heat sink with serrated fins at a 60° inclination provided excellent steady-state temperature control under high-power conditions, with an optimal operating airflow velocity of 3 m/s. This research provides theoretical guidance and technical support for the practical application of U-shaped micro heat pipe heat sinks in low-heat-flux electronic devices.
{"title":"Research on the heat dissipation characteristics of low heat flux devices based on micro heat pipe arrays","authors":"Gang Wang , Jiatai Lin , Zhenhua Quan , Wan Yu , Rongxin Zhu , Tao Hu , Huashan Su","doi":"10.1016/j.icheatmasstransfer.2026.110987","DOIUrl":"10.1016/j.icheatmasstransfer.2026.110987","url":null,"abstract":"<div><div>Addressing the challenges of heat dissipation and non-uniform temperature distribution in low-heat-flux electronic devices, this study designed a U-shaped micro heat pipe heat sink by coupling a micro heat pipe array (MHPA) with fins and systematically analyzed its thermal performance. Experimental results show that under various input power conditions, the U-shaped MHPA at a 60° inclination exhibited superior startup performance and steady-state heat transfer capability. This performance, attributed to an optimal balance between working fluid evaporation and condensate return flow resistance, was significantly better than that at 30° and 90° inclinations. Regarding fin structure, the serrated fin demonstrated the best overall performance under both natural and forced convection, reducing the heat source temperature to 86.6 °C and 37.6 °C, respectively. When the airflow velocity reached 3 m/s, the decreasing trend of the steady-state temperature and thermal response time of the heat source slowed markedly, indicating limited additional benefit from further increasing airflow. Considering the cooling performance across different power inputs and airflow velocities, the U-shaped micro heat pipe heat sink with serrated fins at a 60° inclination provided excellent steady-state temperature control under high-power conditions, with an optimal operating airflow velocity of 3 m/s. This research provides theoretical guidance and technical support for the practical application of U-shaped micro heat pipe heat sinks in low-heat-flux electronic devices.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"175 ","pages":"Article 110987"},"PeriodicalIF":6.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper investigates the flow reconstruction characteristics using combined mechanical spike and porous jet techniques in a Mach 6 hypersonic flow, combining experimental measurements with computational simulations. Experimental results demonstrate high test repeatability and agree well with the corresponding numerical simulations in capturing both flow structures and the pressure distributions. Schlieren images indicate that the combined spike-porous jet techniques effectively reshape the flow morphology, and the reattachment shock is pushed away from the blunt body. Surface pressure measurements show a significant pressure reduction, demonstrating the effectiveness of two novel spike-porous jet configurations. For the opposing jet device, the increase in the jet total pressure ratio further lowers surface pressure, and the jet structure expands. Increasing the single length also reduces the surface pressure along the blunt body, with a notable drop observed as L/D increases from 0.6 to 1.0. Moreover, a self-sustained porous-jet device that requires no external working-fluid supply is proposed, exhibiting strong sensitivity to angle of attack. At 8° angle of attack, the peak pressure coefficient increases by 71.84% compared to the zero-angle-of-attack condition. As the angle of attack increases, schlieren imaging reveals increasingly asymmetric shock patterns, and the windward side exhibits markedly higher pressure coefficients than that on the leeward side.
{"title":"Experimental and numerical investigations of the flow control mechanism with combined spike-porous jet techniques in hypersonic flow","authors":"Yu-shan Meng , Xiao-quan Yang , Hao Dong , Wei Huang , Xu-dong Zhang , Zhi-rong Chen , Xiao-long Tang","doi":"10.1016/j.icheatmasstransfer.2026.110996","DOIUrl":"10.1016/j.icheatmasstransfer.2026.110996","url":null,"abstract":"<div><div>This paper investigates the flow reconstruction characteristics using combined mechanical spike and porous jet techniques in a Mach 6 hypersonic flow, combining experimental measurements with computational simulations. Experimental results demonstrate high test repeatability and agree well with the corresponding numerical simulations in capturing both flow structures and the pressure distributions. Schlieren images indicate that the combined spike-porous jet techniques effectively reshape the flow morphology, and the reattachment shock is pushed away from the blunt body. Surface pressure measurements show a significant pressure reduction, demonstrating the effectiveness of two novel spike-porous jet configurations. For the opposing jet device, the increase in the jet total pressure ratio further lowers surface pressure, and the jet structure expands. Increasing the single length also reduces the surface pressure along the blunt body, with a notable drop observed as <em>L</em>/<em>D</em> increases from 0.6 to 1.0. Moreover, a self-sustained porous-jet device that requires no external working-fluid supply is proposed, exhibiting strong sensitivity to angle of attack. At 8° angle of attack, the peak pressure coefficient increases by 71.84% compared to the zero-angle-of-attack condition. As the angle of attack increases, schlieren imaging reveals increasingly asymmetric shock patterns, and the windward side exhibits markedly higher pressure coefficients than that on the leeward side.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"175 ","pages":"Article 110996"},"PeriodicalIF":6.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388325","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 : 2026-06-01Epub Date: 2026-03-12DOI: 10.1016/j.icheatmasstransfer.2026.110956
Hehe Kang , Xiaojia Li
Efficient boiling heat transfer of liquid hydrogen is essential for cryogenic thermal management in hydrogen energy systems, where heat transfer performance is strongly affected by microscale phase-change processes near solid surfaces. However, the influence of liquid film thickness on nucleation behavior and boiling heat transfer of liquid hydrogen has not been quantitatively clarified. In this study, molecular dynamics simulations are performed to investigate the boiling characteristics of liquid hydrogen films with varying thicknesses under wall heating conditions. The results show that liquid film thickness plays a dominant role in determining boiling regimes and heat transfer performance. For ultrathin films with thicknesses below approximately 3 nm, heat transfer is governed by rapid evaporation without bubble nucleation. In contrast, stable vapor nucleation and subsequent bubble growth occur only when a continuous liquid film thicker than about 3 nm is present. Analysis of energy evolution reveals distinct turning points in kinetic and potential energies associated with nucleation events, and a critical kinetic energy rate of approximately 0.95 kcal/mol is identified as a criterion for nucleation onset, independent of film thickness and wall temperature. Increasing wall temperature accelerates nucleation and enhances bubble growth, resulting in increased heat flux. However, excessive wall heating induces liquid film detachment from the solid surface, leading to a reduction in heat flux and an increase in interfacial thermal resistance. Based on the simulation data, empirical correlations are developed to predict heat flux and heat transfer coefficients as functions of liquid film thickness and wall temperature, with prediction errors within 30%. These results provide quantitative insight into the microscale boiling behavior of liquid hydrogen and offer useful guidance for modeling and optimizing cryogenic phase-change heat transfer in hydrogen energy applications.
{"title":"Deciphering energy-driven nucleation and boiling dynamics of liquid hydrogen at cryogenic conditions","authors":"Hehe Kang , Xiaojia Li","doi":"10.1016/j.icheatmasstransfer.2026.110956","DOIUrl":"10.1016/j.icheatmasstransfer.2026.110956","url":null,"abstract":"<div><div>Efficient boiling heat transfer of liquid hydrogen is essential for cryogenic thermal management in hydrogen energy systems, where heat transfer performance is strongly affected by microscale phase-change processes near solid surfaces. However, the influence of liquid film thickness on nucleation behavior and boiling heat transfer of liquid hydrogen has not been quantitatively clarified. In this study, molecular dynamics simulations are performed to investigate the boiling characteristics of liquid hydrogen films with varying thicknesses under wall heating conditions. The results show that liquid film thickness plays a dominant role in determining boiling regimes and heat transfer performance. For ultrathin films with thicknesses below approximately 3 nm, heat transfer is governed by rapid evaporation without bubble nucleation. In contrast, stable vapor nucleation and subsequent bubble growth occur only when a continuous liquid film thicker than about 3 nm is present. Analysis of energy evolution reveals distinct turning points in kinetic and potential energies associated with nucleation events, and a critical kinetic energy rate of approximately 0.95 kcal/mol is identified as a criterion for nucleation onset, independent of film thickness and wall temperature. Increasing wall temperature accelerates nucleation and enhances bubble growth, resulting in increased heat flux. However, excessive wall heating induces liquid film detachment from the solid surface, leading to a reduction in heat flux and an increase in interfacial thermal resistance. Based on the simulation data, empirical correlations are developed to predict heat flux and heat transfer coefficients as functions of liquid film thickness and wall temperature, with prediction errors within 30%. These results provide quantitative insight into the microscale boiling behavior of liquid hydrogen and offer useful guidance for modeling and optimizing cryogenic phase-change heat transfer in hydrogen energy applications.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"175 ","pages":"Article 110956"},"PeriodicalIF":6.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388254","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 : 2026-06-01Epub Date: 2026-03-12DOI: 10.1016/j.icheatmasstransfer.2026.110978
Chengyun Xin , Ben Sun , Lei Qin , Shaoliang Yin , Changxin Lu , Zhong Huang , Tairan Fu
It is necessary to quantitatively describe the local thermal-hydraulic performance for enhancing convective heat transfer. For heat exchange tubes, this paper uses the product of their specific surface area and logarithmic mean temperature difference as the temperature gradient scale, establishes a quantitative relationship between the ratio of heat transfer to power consumption and local pressure, temperature, and velocity, and thus proposes a thermal-hydraulic synergy number which consists of four factors: dimensionless temperature gradient , the cosine of synergy angle , local friction coefficient , and Reynolds number . Periodic models with both bare tubes and integrally-molded spiral finned (IMSF) tubes were established and numerically solved to analyze the local thermal-hydraulic performance. The results indicate that determines the positive or negative effect of local thermal-hydraulic performance, the highest occurs near the front stagnation point of each tube row and the worst is observed after the flow separation point, and exhibits an increasing trend with flow velocity, remains essentially constant, but both and the comprehensive performance factor gradually decrease with increasing velocity. Also, is affected by fin configuration, and for Case 3 is reduced by 29% compared to that for Case 1. The fin cross-sectional shape has limited influence on the overall distribution pattern of local thermal-hydraulic performance of the tubes, but significantly affects the local intensity. This study has certain guiding significance for evaluation of local thermal-hydraulic performance and optimization of enhanced heat transfer surfaces.
{"title":"Local thermal-hydraulic synergy analysis of heat exchange tubes for convective heat transfer enhancement","authors":"Chengyun Xin , Ben Sun , Lei Qin , Shaoliang Yin , Changxin Lu , Zhong Huang , Tairan Fu","doi":"10.1016/j.icheatmasstransfer.2026.110978","DOIUrl":"10.1016/j.icheatmasstransfer.2026.110978","url":null,"abstract":"<div><div>It is necessary to quantitatively describe the local thermal-hydraulic performance for enhancing convective heat transfer. For heat exchange tubes, this paper uses the product of their specific surface area and logarithmic mean temperature difference as the temperature gradient scale, establishes a quantitative relationship between the ratio of heat transfer to power consumption and local pressure, temperature, and velocity, and thus proposes a thermal-hydraulic synergy number <span><math><mi>η</mi></math></span> which consists of four factors: dimensionless temperature gradient <span><math><msub><mi>k</mi><mi>local</mi></msub></math></span>, the cosine of synergy angle <span><math><mi>cos</mi><mi>α</mi></math></span>, local friction coefficient <span><math><msub><mi>f</mi><mi>local</mi></msub></math></span>, and Reynolds number <span><math><mi>Re</mi></math></span>. Periodic models with both bare tubes and integrally-molded spiral finned (IMSF) tubes were established and numerically solved to analyze the local thermal-hydraulic performance. The results indicate that <span><math><mi>cos</mi><mi>α</mi></math></span> determines the positive or negative effect of local thermal-hydraulic performance, the highest occurs near the front stagnation point of each tube row and the worst is observed after the flow separation point, and <span><math><mover><mrow><mi>cos</mi><mi>α</mi></mrow><mo>¯</mo></mover></math></span> exhibits an increasing trend with flow velocity, <span><math><mover><msub><mi>k</mi><mi>local</mi></msub><mo>¯</mo></mover></math></span> remains essentially constant, but both <span><math><mover><msub><mi>f</mi><mi>local</mi></msub><mo>¯</mo></mover></math></span> and the comprehensive performance factor <span><math><mi>ξ</mi></math></span> gradually decrease with increasing velocity. Also, <span><math><mover><msub><mi>f</mi><mi>local</mi></msub><mo>¯</mo></mover></math></span> is affected by fin configuration, and <span><math><mover><msub><mi>f</mi><mi>local</mi></msub><mo>¯</mo></mover></math></span> for Case 3 is reduced by 29% compared to that for Case 1. The fin cross-sectional shape has limited influence on the overall distribution pattern of local thermal-hydraulic performance of the tubes, but significantly affects the local intensity. This study has certain guiding significance for evaluation of local thermal-hydraulic performance and optimization of enhanced heat transfer surfaces.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"175 ","pages":"Article 110978"},"PeriodicalIF":6.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388272","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 : 2026-06-01Epub Date: 2026-03-11DOI: 10.1016/j.icheatmasstransfer.2026.111004
Changda Nie , Haitao Wang , Hongyang Li , Jiangwei Liu , Xinjian Liu , Zhonghao Rao
Pin-fins microchannel heat sinks (PFMCHSs) demonstrate outstanding cooling performance for electronic devices. However, the flow dead zone formed behind the pin-fins remains critical drawbacks in practical applications. To address this issue, this study proposes an associated diversion structure (ADS) integrated into the PFMCHS. Three-dimensional simulation, validated against experimental data, was employed to elucidate the underlying enhancement mechanism. A parametric study systematically investigates the effects of the ADS height, horizontal and vertical distances relative to the pin-fins, and diameter on thermal and hydraulic characteristics. These results are compared to a conventional PFMCHS with pin-fins heigh, diameter and spacing of 1.0, 0.5 and 1.5 mm respectively under a reduced solid volume fraction. Results indicate that the incorporation of ADS effectively redirects fluid flow behind the pin-fins, thereby suppressing flow dead region and promoting cold and hot fluids mixing. The beneficial effect becomes increasingly pronounced with the decrease of vertical offset and increases of height, horizontal offset and diameter. The optimum ADS configuration achieves a 19.3–21.1% reduction in maximum temperature at inlet velocity range of 0.15–0.35 m/s, accompanied by 153.7–225.3% increase in pressure drop, and 1.84–1.97 times PEC compared to the conventional PFMCHS. Furthermore, within a pumping power range of 0.15–0.8 mW, thermal resistance of the optimal configuration is reduced by 20.8–22.2% compared to the conventional PFMCHS.
{"title":"Flow and heat transfer characteristics of pin-fin microchannel heat sink with associated diversion structure","authors":"Changda Nie , Haitao Wang , Hongyang Li , Jiangwei Liu , Xinjian Liu , Zhonghao Rao","doi":"10.1016/j.icheatmasstransfer.2026.111004","DOIUrl":"10.1016/j.icheatmasstransfer.2026.111004","url":null,"abstract":"<div><div>Pin-fins microchannel heat sinks (PFMCHSs) demonstrate outstanding cooling performance for electronic devices. However, the flow dead zone formed behind the pin-fins remains critical drawbacks in practical applications. To address this issue, this study proposes an associated diversion structure (ADS) integrated into the PFMCHS. Three-dimensional simulation, validated against experimental data, was employed to elucidate the underlying enhancement mechanism. A parametric study systematically investigates the effects of the ADS height, horizontal and vertical distances relative to the pin-fins, and diameter on thermal and hydraulic characteristics. These results are compared to a conventional PFMCHS with pin-fins heigh, diameter and spacing of 1.0, 0.5 and 1.5 mm respectively under a reduced solid volume fraction. Results indicate that the incorporation of ADS effectively redirects fluid flow behind the pin-fins, thereby suppressing flow dead region and promoting cold and hot fluids mixing. The beneficial effect becomes increasingly pronounced with the decrease of vertical offset and increases of height, horizontal offset and diameter. The optimum ADS configuration achieves a 19.3–21.1% reduction in maximum temperature at inlet velocity range of 0.15–0.35 m/s, accompanied by 153.7–225.3% increase in pressure drop, and 1.84–1.97 times PEC compared to the conventional PFMCHS. Furthermore, within a pumping power range of 0.15–0.8 mW, thermal resistance of the optimal configuration is reduced by 20.8–22.2% compared to the conventional PFMCHS.</div></div>","PeriodicalId":332,"journal":{"name":"International Communications in Heat and Mass Transfer","volume":"175 ","pages":"Article 111004"},"PeriodicalIF":6.4,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388326","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 : 2026-06-01Epub Date: 2026-03-11DOI: 10.1016/j.icheatmasstransfer.2026.110976
Zaki Mrzog Alaofi , A. El-Dali
The interaction between optical excitation, thermal effects, acoustic waves, and moisture diffusion plays a crucial role in determining the performance and reliability of semiconductor materials operating under coupled environmental conditions. In this context, the present study investigates the coupled photo-thermo-acoustoelastic response of a semiconductor medium subjected to photothermal excitation, while accounting for the simultaneous effects of moisture diffusion and the hygrothermal parameter. The governing field equations describing the interactions among temperature, carrier density, acoustic pressure, moisture concentration, and volumetric strain are formulated within the framework of classical thermoelasticity. By employing the normal-mode technique, the coupled system of partial differential equations is reduced to a tractable mathematical form, enabling the derivation of two-dimensional analytical solutions for the volumetric strain field. The solutions are evaluated numerically to characterize the dynamic behavior of silicon (Si), and the results are presented as two-dimensional spatial field distributions (2D heat maps) that illustrate the coupling and spatial evolution of the physical fields. The results demonstrate that moisture diffusion and hygrothermal coupling significantly influence the thermal, mechanical, and acoustic responses of the semiconductor. These effects act as natural damping mechanisms that reduce temperature rise, attenuate acoustic amplitudes, and limit stress accumulation. Furthermore, the hygrothermal parameter enhances heat-moisture cross-diffusion, leading to faster energy dissipation and improved structural relaxation. From an application perspective, the findings provide useful insights for the design and optimization of photoacoustic sensors, semiconductor cooling strategies, and humidity-sensitive optoelectronic devices, where coupled heat-moisture-stress interactions strongly affect device performance and reliability.
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Pub Date : 2026-06-01Epub Date: 2026-03-12DOI: 10.1016/j.icheatmasstransfer.2026.111015
Qi Wang , Shuicai Wu , Luyu Li , Hongjian Gao , Weiwei Wu
Purpose
This study focuses on the heat-transfer performance of single-needle multi-point microwave ablation (MWA), emphasizing the effects on the coagulation zone and the temperature distribution. The objective is to clarify the heat transfer and energy diffusion characteristics during the ablation of large liver tumors (>3 cm).
Materials and methods
A finite element-based numerical simulation model of single-needle multi-point MWA was established and validated using ex vivo porcine liver experiments. Different time-allocation schemes (2 min–6 min, 4 min–4 min) and pull-back distances (5 mm, 10 mm) were investigated to analyze their influence on heat transfer and thermal field evolution. Statistical analyses of parameter effects were performed using the t-test (p < 0.05).
Results
The single-needle multi-point ablation approach effectively enhanced overall heat transfer and produced a larger, more uniform coagulation zone. Pull-back distance had a significant impact (p < 0.05) on the longitudinal temperature and coagulation morphology, with longer distances generating extended thermal fields. Under a fixed total ablation time, the time-allocation scheme has a relatively minor impact on the heat transfer process.
目的研究单针多点微波烧蚀（MWA）的传热性能，重点研究其对混凝区和温度分布的影响。目的是阐明大肝肿瘤（> 3cm）消融过程中的传热和能量扩散特征。材料与方法建立了基于有限元的单针多点MWA数值模拟模型，并通过离体猪肝实验进行了验证。研究了不同的时间分配方案（2 min - 6 min, 4 min - 4 min）和回拉距离（5 mm, 10 mm）对换热和热场演化的影响。参数效应的统计分析采用t检验（p < 0.05）。结果单针多点烧蚀能有效增强整体换热，产生更大、更均匀的混凝区。拉离距离对纵向温度和凝固形态有显著影响（p < 0.05），拉离距离越远，热场越宽。在总烧蚀时间一定的情况下，时间分配方案对换热过程的影响较小。
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