International Journal of Heat and Mass Transfer最新文献_第2页

Exact analytical solution for thermal conduction in a Cartesian body with heat-generating regions of arbitrary shapes and thermal properties

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Heat and Mass Transfer

Pub Date : 2025-04-10 DOI: 10.1016/j.ijheatmasstransfer.2025.126968

Ankur Jain, Girish Krishnan

Despite considerable advances in numerical simulations, the development of analytical tools for exact solutions of thermal conduction problems remains to be of much importance. While multiple techniques are available for analyzing thermal conduction in a homogeneous body, it is a lot more challenging to derive exact solutions for problems containing multiple materials, particularly when the geometry may be irregular. For example, solving the problem of circular heat-generating regions of different thermal properties inside a Cartesian body – such as in a Li-ion battery pack – presents considerable theoretical difficulties. This work presents an exact analytical technique for solving thermal conduction problems containing multiple heat-generating regions of arbitrary non-Cartesian shapes and distinct thermal properties within a Cartesian body. The spatial distribution of heat generation and thermal properties of the non-Cartesian regions is represented mathematically using Heaviside step functions. Closed-form expressions for the coefficients of a series solution for the transient and steady state temperature fields are derived using the differential and integral properties of Heaviside functions. In limiting conditions, these expressions are shown to correctly reduce to well-known results for homogeneous bodies. Good agreement with numerical simulations, and with past work for a specific two-layer problem is also demonstrated. The general technique developed here is used to solve a variety of geometrically complex problems that are not solvable using traditional analytical methods, such as one with four heat-generating sources of different shapes and materials, transient thermal conduction due to a heart-shaped heater and a thermal decay problem. While such problems may be solved using numerical simulations, analytical techniques such as the one developed here advance the theoretical understanding of thermal conduction, and are often more practical to implement in real-life engineering scenarios, such as battery thermal management and composites manufacturing.

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引用次数: 0

Anisotropic capillary-driven evaporation performance on laser textured prismatic micropillars

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Heat and Mass Transfer

Pub Date : 2025-04-09 DOI: 10.1016/j.ijheatmasstransfer.2025.126972

Hongpeng Jiang , Zhiming Xu , Xiaoliang Wang , Hong Qi , Debin Shan , Bin Guo , Jie Xu

Wicking is an essential characteristic in the operation of passive phase-change cooling devices, as it provides efficient thin film evaporation through micro/nano structures and improves liquid rewetting via capillary pumping. However, there is no consensus on how anisotropic wicking affects evaporation and droplet hydrodynamics at varying substrate temperatures. In this work, we fabricated prismatic micropillar on AA6063 surfaces with different intersection angle by laser texturing to analyze their effect on wicking dynamics and heat transfer during droplet evaporation via high-speed and infrared camera. The experiments revealed that when the droplet wetted the prismatic micropillar surfaces with different intersection angle, there was a significant difference in wicking speed between the long and short axes, and the maximum speed difference in the first 1 s could reach 25.1 mm/s for PM-15. Due to the guiding effect of the intersection angle and the balance between capillary force and viscous resistance, the wicking distance ratio between the long and short axes was approximately equal to tan(α/2) during the bulk existence stage. The laser-induced surface realized a maximum evaporation rate of 19.4 μL/s at 90 °C, achieving an enhancement factor f_e of 30.95 compared to a smooth surface. Evaporation enhancement on prismatic micropillar surfaces cannot be attributed solely to the wicking direction or wicking area, but rather to a function of roughness and wickability. When the surface temperature is too high, droplets undergo nucleate boiling, and the main reason for mass loss of the droplet is primarily splashing rather than evaporation. Further, we introduce the primary force interactions involved in high-temperature droplet evaporation process and emphasize the influence of the anisotropic surface structures on droplet dynamics.

{"title":"Anisotropic capillary-driven evaporation performance on laser textured prismatic micropillars","authors":"Hongpeng Jiang , Zhiming Xu , Xiaoliang Wang , Hong Qi , Debin Shan , Bin Guo , Jie Xu","doi":"10.1016/j.ijheatmasstransfer.2025.126972","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.126972","url":null,"abstract":"<div><div>Wicking is an essential characteristic in the operation of passive phase-change cooling devices, as it provides efficient thin film evaporation through micro/nano structures and improves liquid rewetting via capillary pumping. However, there is no consensus on how anisotropic wicking affects evaporation and droplet hydrodynamics at varying substrate temperatures. In this work, we fabricated prismatic micropillar on AA6063 surfaces with different intersection angle by laser texturing to analyze their effect on wicking dynamics and heat transfer during droplet evaporation via high-speed and infrared camera. The experiments revealed that when the droplet wetted the prismatic micropillar surfaces with different intersection angle, there was a significant difference in wicking speed between the long and short axes, and the maximum speed difference in the first 1 s could reach 25.1 mm/s for PM-15. Due to the guiding effect of the intersection angle and the balance between capillary force and viscous resistance, the wicking distance ratio between the long and short axes was approximately equal to tan(<em>α</em>/2) during the bulk existence stage. The laser-induced surface realized a maximum evaporation rate of 19.4 μL/s at 90 °C, achieving an enhancement factor <em>f</em><sub>e</sub> of 30.95 compared to a smooth surface. Evaporation enhancement on prismatic micropillar surfaces cannot be attributed solely to the wicking direction or wicking area, but rather to a function of roughness and wickability. When the surface temperature is too high, droplets undergo nucleate boiling, and the main reason for mass loss of the droplet is primarily splashing rather than evaporation. Further, we introduce the primary force interactions involved in high-temperature droplet evaporation process and emphasize the influence of the anisotropic surface structures on droplet dynamics.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"246 ","pages":"Article 126972"},"PeriodicalIF":5.0,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799734","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}

引用次数: 0

D-optimization of three-layer experimental set-ups for simultaneous estimation of transport thermal properties of FRP composites using contact and non-contact rear temperature measurements

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Heat and Mass Transfer

Pub Date : 2025-04-09 DOI: 10.1016/j.ijheatmasstransfer.2025.127019

Giampaolo D'Alessandro

A D-optimization problem, dealing with three-layer experimental set-ups for simultaneous estimation of the transport thermal properties of FRP composites, is faced. These experimental set-ups are two different configurations of the plane-source method, and they consist of a thin electrical heater placed between two larger composite specimens of the same thickness. Both set-ups are modeled through only one orthotropic rectangular plate (sample) partially heated at the front boundary through a surface heat flux (2D heat diffusion), while just the opposite boundary is subject to a third kind boundary condition. The related heat transfer coefficient simulates the operating conditions when recording temperature readings at the sample backside using either non-contact techniques or thermocouples. Indeed, in the first case it accounts only for free convection with the surrounding air, while in the latter it accounts for both an insulating material and convective heat transfer with the environment.

This paper offers a systematic approach for the optimization of the whole experiment (i.e., the experimental variables and the set of unknown parameters) for thermal properties estimation of FRP composites. As the set-up optimization problem is often faced only partially by the experimentalists, the systematic approach here shown is the novelty of the work. In detail, the optimum set-up is designed for different thermal conductivity ratios of the sample through a D-optimization procedure, named Δ⁺ criterion. Its systematical application not only allows to find the optimum set of parameters to be estimated, but it also allows the heating and experiment times, sample aspect ratio, width of the heated region and measurement points location to be optimized. Expected standard deviations of the estimates are also computed. Optimization results show that the sample should be heated up to 80 % of its height, while the optimum sample aspect ratio is found to be related to the thermal conductivity ratio.

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引用次数: 0

Study on oil cooling method for the powertrain of electric vehicles

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Heat and Mass Transfer

Pub Date : 2025-04-09 DOI: 10.1016/j.ijheatmasstransfer.2025.127073

Youngkyo Kim , Tae Young Beom , Tae Wook Ha , Sung Wook Lee , In Guk Hwang , Dong Kyu Kim

This study presents a thermal-fluid analysis of an electric vehicle (EV) powertrain to evaluate the effectiveness and limitation of oil cooling. A validated numerical model was developed to investigate oil flow behavior, churning effects, and temperature distribution. Results show uneven oil distribution in the motor chamber. Only 22.6 % of the cooling oil reached the drive-end winding, while 46 % reached the non-drive end. As a result, the drive end experienced a 4.2 % higher temperature than the non-drive end. The stator temperature was 4.9 % higher than the windings, and the rotor exhibited the highest temperature due to inefficient heat dissipation. Additionally, oil recirculation from the reducer (0.02 L/s) reduced cooling efficiency, particularly under high-load conditions. These findings provide critical insights into the thermal challenges of EV powertrains and serve as a foundation for optimizing oil flow, developing hybrid cooling strategies, and improving thermal management in next-generation EVs.

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引用次数: 0

Enhanced subcooled flow boiling in microchannels integrated with nanoporous graphene coatings of distinctive wettability

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Heat and Mass Transfer

Pub Date : 2025-04-09 DOI: 10.1016/j.ijheatmasstransfer.2025.127065

Edmund Chong Jie Ng, Yew Mun Hung

Subcooled flow boiling in microchannel presents a promising solution for efficient electronics cooling. This study explores the use of graphene nanoplatelets (GNPs) as a nanoporous surface coating to leverage the ultrafast water permeation and variable wettability properties of graphene in subcooled flow boiling through microchannels. The performance of GNPs coatings is evaluated using metrics such as the Nusselt number, pumping power, flow resistance, and performance evaluation criterion. The results demonstrate that the base GNPs coating, exhibiting dual wetting characteristics due to its synergistic combination of hydrophobicity and high surface roughness, outperforms both purely superhydrophilic and superhydrophobic GNPs coatings. The base GNPs coating achieves an impressive 143% increase in the Nusselt number and reduces the surface temperature by up to 25°C. However, the enhanced boiling performance with the base GNPs comes at the expense of increased pumping power, analogous to the use of inserts in channel flow. The improved heat transfer is coupled with higher flow resistance and energy consumption, leading to a performance evaluation criterion value well below unity. This study provides interesting insights into the application of GNPs in subcooled flow boiling in microchannels to improve the efficiency of electronics cooling.

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引用次数: 0

Thermocapillary instabilities in thin liquid films on a rotating cylinder

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Heat and Mass Transfer

Pub Date : 2025-04-09 DOI: 10.1016/j.ijheatmasstransfer.2025.127033

Souradip Chattopadhyay , Amar K. Gaonkar , Hangjie Ji

Thin liquid films flowing along rotating cylinders are crucial in many industrial processes such as centrifugal thin-film evaporators. The thermocapillary instability in these films often leads to operational inefficiencies and stability concerns. To improve the design and operation of these systems under thermal effects, achieving a uniform distribution of the coating layer is crucial. This challenge becomes even more complex when the cylinder is simultaneously heated and rotated. A comprehensive understanding of these coupled effects is essential for uplifting the efficiency and effectiveness of these systems in practical applications. In this study, we present a model for a thin liquid film flowing along the inner surface of a rotating cylinder subjected to nonuniform heating. Using a long-wave approximation to describe interface dynamics, our study formulates a full lubrication equation incorporating thermal boundary conditions, nonlinear curvature terms, and rotational effects. Linear stability analysis indicates that the Rayleigh-Plateau instability can be suppressed by rotating the cylinder. When the wall is uniformly heated, the reinforced instability can also be suppressed by introducing rotation. Additionally, we investigate the influence of thermocapillarity and rotation on wave speed and the stability of traveling wave solutions. Furthermore, we numerically study the self-similar solution in plug formation and obtain the scaling

{(t_{c} - t)}^{1 / 5}

, where

t_{c}

is the choke time. We find the exponent 1/5 is independent of rotation but

t_{c}

increases with higher rotation. Numerical simulation reveals that nonuniform heating exacerbates surface wave instability and plug formation (or choke behavior), while cylinder rotation can potentially delay plug formation. Our analysis shows that an increasing Biot number can induce choke behavior in a uniformly heated cylinder, but the introduction of rotation can delay the onset of choking.

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引用次数: 0

Additively manufactured inconel 718 vapor chamber with conformal micro-pillar wicks: A low temperature concept demonstration

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Heat and Mass Transfer

Pub Date : 2025-04-09 DOI: 10.1016/j.ijheatmasstransfer.2025.127056

Adnen Mezghani , Corey J. Dickman , Edward W. Reutzel , Abdalla R. Nassar , Douglas E. Wolfe

Effective thermal management is crucial in hypersonic flight (Mach > 5) due to extremely high aerodynamic heating located at leading edges, and both passive and active thermal protection systems (TPS) have been used to address this. Among passive TPS options are two-phase thermal management systems, such as heat pipes (HP) and vapor chambers (VC), which can realize a considerable reduction in steady-state leading edge temperature owing to their extremely high heat transfer capability. This leads to reduction in complexity and cost of TPS structure and material requirements. However, conventional HP and VC fabrication methods require multiple manufacturing and assembly steps, limiting their design space. Alternatively, utilizing additive manufacturing (AM) for fabrication can bypass conventional manufacturing limitations and enable structural members with intricate internal channels and topologically optimized shapes. AM can, therefore, unveil a larger design space for tailored leading edge concepts with an integrated passive TPS. This work demonstrates the design, fabrication and testing of a notional methanol-filled Inconel 718 VC with a conformal micro-pillar wick fabricated via laser-beam powder bed fusion AM. This serves as a proof of concept and establishes a foundation for design and fabrication of high-temperature additively manufactured sodium-filled leading edge VCs.

{"title":"Additively manufactured inconel 718 vapor chamber with conformal micro-pillar wicks: A low temperature concept demonstration","authors":"Adnen Mezghani , Corey J. Dickman , Edward W. Reutzel , Abdalla R. Nassar , Douglas E. Wolfe","doi":"10.1016/j.ijheatmasstransfer.2025.127056","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.127056","url":null,"abstract":"<div><div>Effective thermal management is crucial in hypersonic flight (Mach > 5) due to extremely high aerodynamic heating located at leading edges, and both passive and active thermal protection systems (TPS) have been used to address this. Among passive TPS options are two-phase thermal management systems, such as heat pipes (HP) and vapor chambers (VC), which can realize a considerable reduction in steady-state leading edge temperature owing to their extremely high heat transfer capability. This leads to reduction in complexity and cost of TPS structure and material requirements. However, conventional HP and VC fabrication methods require multiple manufacturing and assembly steps, limiting their design space. Alternatively, utilizing additive manufacturing (AM) for fabrication can bypass conventional manufacturing limitations and enable structural members with intricate internal channels and topologically optimized shapes. AM can, therefore, unveil a larger design space for tailored leading edge concepts with an integrated passive TPS. This work demonstrates the design, fabrication and testing of a notional methanol-filled Inconel 718 VC with a conformal micro-pillar wick fabricated via laser-beam powder bed fusion AM. This serves as a proof of concept and establishes a foundation for design and fabrication of high-temperature additively manufactured sodium-filled leading edge VCs.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"246 ","pages":"Article 127056"},"PeriodicalIF":5.0,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799731","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}

引用次数: 0

Multiphase flow and interface dynamics in a blast furnace hearth: Effects of slag viscosity and coke diameter

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Heat and Mass Transfer

Pub Date : 2025-04-09 DOI: 10.1016/j.ijheatmasstransfer.2025.127085

Dong Jo Lee , Hyun Sik Yoon , Adarsh Rajasekharan Nair , Min IL Kim

This study numerically investigates the effects of slag viscosity (

μ_{s}

) and coke diameter (

D_{P}

) on the behavior of gas-slag and slag-iron interfaces, as well as the mass flow rates of slag and iron, in a three-dimensional (3D) full-scale blast furnace hearth model with four tapholes undergoing tapping and plugging cycles. This study introduces new perspectives by focusing on the bifurcation behavior of interface evolution, the classification of two distinct regimes in temporal levels, and circumferential variations in interface dynamics along the side wall. The slag-iron interface exhibited linear descent followed by saturation, while the gas-slag interface underwent linear descent followed by acceleration. Bifurcation at the onset of slag drainage, occurring earlier with larger

D_{P}

and lower

μ_{s}

, marked a critical shift in dynamics. Before bifurcation,

D_{P}

governed interface descent; after bifurcation,

μ_{s}

dominated, lowering pressure and increasing the pressure gradient near the taphole. These findings include novel insights into localized dynamics, revealing sharper circumferential gradients under conditions of higher

μ_{s}

and smaller

D_{P}

. Despite variations, slag and iron layer thickness ratios remained stable, reflecting their independence from

μ_{s}

and

D_{P}

. Additionally, a critical intersection point in mass flow rates was identified, where slag flow surpassed iron flow. This point, delayed under conditions of higher

μ_{s}

and smaller

D_{P}

, highlighted the influence of reduced fluidity on two-phase outflow dynamics. These findings highlight the potential of optimizing

μ_{s}

and

D_{P}

to enhance fluidity, production, energy efficiency and sustainability in blast furnace operations.

{"title":"Multiphase flow and interface dynamics in a blast furnace hearth: Effects of slag viscosity and coke diameter","authors":"Dong Jo Lee , Hyun Sik Yoon , Adarsh Rajasekharan Nair , Min IL Kim","doi":"10.1016/j.ijheatmasstransfer.2025.127085","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.127085","url":null,"abstract":"<div><div>This study numerically investigates the effects of slag viscosity (<span><math><msub><mi>μ</mi><mi>s</mi></msub></math></span>) and coke diameter (<span><math><msub><mi>D</mi><mi>P</mi></msub></math></span>) on the behavior of gas-slag and slag-iron interfaces, as well as the mass flow rates of slag and iron, in a three-dimensional (3D) full-scale blast furnace hearth model with four tapholes undergoing tapping and plugging cycles. This study introduces new perspectives by focusing on the bifurcation behavior of interface evolution, the classification of two distinct regimes in temporal levels, and circumferential variations in interface dynamics along the side wall. The slag-iron interface exhibited linear descent followed by saturation, while the gas-slag interface underwent linear descent followed by acceleration. Bifurcation at the onset of slag drainage, occurring earlier with larger <span><math><mrow><msub><mi>D</mi><mi>P</mi></msub><mspace></mspace></mrow></math></span>and lower <span><math><msub><mi>μ</mi><mi>s</mi></msub></math></span>, marked a critical shift in dynamics. Before bifurcation, <span><math><mrow><msub><mi>D</mi><mi>P</mi></msub><mspace></mspace></mrow></math></span>governed interface descent; after bifurcation, <span><math><mrow><msub><mi>μ</mi><mi>s</mi></msub><mspace></mspace></mrow></math></span>dominated, lowering pressure and increasing the pressure gradient near the taphole. These findings include novel insights into localized dynamics, revealing sharper circumferential gradients under conditions of higher <span><math><mrow><msub><mi>μ</mi><mi>s</mi></msub><mspace></mspace></mrow></math></span>and smaller <span><math><msub><mi>D</mi><mi>P</mi></msub></math></span>. Despite variations, slag and iron layer thickness ratios remained stable, reflecting their independence from <span><math><mrow><msub><mi>μ</mi><mi>s</mi></msub><mspace></mspace></mrow></math></span>and <span><math><msub><mi>D</mi><mi>P</mi></msub></math></span>. Additionally, a critical intersection point in mass flow rates was identified, where slag flow surpassed iron flow. This point, delayed under conditions of higher <span><math><mrow><msub><mi>μ</mi><mi>s</mi></msub><mspace></mspace></mrow></math></span>and smaller <span><math><msub><mi>D</mi><mi>P</mi></msub></math></span>, highlighted the influence of reduced fluidity on two-phase outflow dynamics. These findings highlight the potential of optimizing <span><math><mrow><msub><mi>μ</mi><mi>s</mi></msub><mspace></mspace></mrow></math></span>and <span><math><mrow><msub><mi>D</mi><mi>P</mi></msub><mspace></mspace></mrow></math></span>to enhance fluidity, production, energy efficiency and sustainability in blast furnace operations.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"246 ","pages":"Article 127085"},"PeriodicalIF":5.0,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799733","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}

引用次数: 0

A novel vapor chamber with gradient capillary wick and larger expansion area

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Heat and Mass Transfer

Pub Date : 2025-04-09 DOI: 10.1016/j.ijheatmasstransfer.2025.127021

Shichao Bu , Haoran Li , Xiaoping Yang , Yonghai Zhang , Kaiwen Duan , Hongwei Bai , Jinjia Wei

As chip integration and performance increased, power consumption grew, making thermal management critical. While vapor chambers offered efficient heat transfer, uniform heat distribution, and simple structures, the capillary force of grooved and mesh designs were insufficient to meet higher cooling demands, highlighting the need for more efficient technologies. This study presents a longitudinally gradient sintered capillary copper-based vapor chamber to overcome the limitations of traditional grooved and mesh structures, enhancing liquid transport and accelerating the internal cycle for improved liquid supply to the evaporation zone. The working fluid employed in the experimental setup consisted of deionized water, making the design suitable for higher heat flux and power conditions. Thermal characterization of the vapor chamber was conducted through a liquid cooling plate, and the effects of different inclination angles and coolant temperatures on performance were systematically studied. Experimental results showed that inclination angle had little effect on performance, with thermal resistance increasing by only 0.007 K/W when operated vertically compared to horizontally. Additionally, raising the coolant temperature significantly improved heat transfer performance, reducing thermal resistance by 26.1 % at 40 °C compared to 20 °C. Furthermore, Experimental results demonstrated that the vapor chamber maintained stable functionality under power inputs reaching up to 1200 W. corresponding to a heat flux of 240 W/cm², at this time, the thermal resistance was 0.047K/W, indicating its potential for managing extremely high-power chips.

{"title":"A novel vapor chamber with gradient capillary wick and larger expansion area","authors":"Shichao Bu , Haoran Li , Xiaoping Yang , Yonghai Zhang , Kaiwen Duan , Hongwei Bai , Jinjia Wei","doi":"10.1016/j.ijheatmasstransfer.2025.127021","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.127021","url":null,"abstract":"<div><div>As chip integration and performance increased, power consumption grew, making thermal management critical. While vapor chambers offered efficient heat transfer, uniform heat distribution, and simple structures, the capillary force of grooved and mesh designs were insufficient to meet higher cooling demands, highlighting the need for more efficient technologies. This study presents a longitudinally gradient sintered capillary copper-based vapor chamber to overcome the limitations of traditional grooved and mesh structures, enhancing liquid transport and accelerating the internal cycle for improved liquid supply to the evaporation zone. The working fluid employed in the experimental setup consisted of deionized water, making the design suitable for higher heat flux and power conditions. Thermal characterization of the vapor chamber was conducted through a liquid cooling plate, and the effects of different inclination angles and coolant temperatures on performance were systematically studied. Experimental results showed that inclination angle had little effect on performance, with thermal resistance increasing by only 0.007 K/W when operated vertically compared to horizontally. Additionally, raising the coolant temperature significantly improved heat transfer performance, reducing thermal resistance by 26.1 % at 40 °C compared to 20 °C. Furthermore, Experimental results demonstrated that the vapor chamber maintained stable functionality under power inputs reaching up to 1200 W. corresponding to a heat flux of 240 W/cm², at this time, the thermal resistance was 0.047K/W, indicating its potential for managing extremely high-power chips.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"246 ","pages":""},"PeriodicalIF":5.0,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799534","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}

引用次数: 0

Experimental investigation on the startup behavior and visualization of dual-evaporator loop heat pipes

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Heat and Mass Transfer

Pub Date : 2025-04-09 DOI: 10.1016/j.ijheatmasstransfer.2025.127053

Andhy M. Fathoni , Priska A. Hendrayanto , Ranggi S. Ramadhan , Nandy Putra

This study investigates the startup behavior and flow dynamics of a dual-evaporator loop heat pipe (DE-LHP) using neutron radiography. The DE-LHP is designed to overcome the challenges of efficiently managing multiple heat sources. Neutron radiography allows visualization of the liquid and vapor distributions, revealing phenomena like vapor backflow, liquid carryover, and heat leakage. Experiments were conducted with various heat load configurations, including balanced and unbalanced distributions, and different geometric orientations. The results show that at a balanced heat load (120 W total), the system reaches steady-state in 500 s with a thermal resistance of 0.14 °C/W while the highest thermal resistance of 0.64 °C/W was observed in the unequal heat load case of 56 W. The unbalanced heat load increases the thermal resistance and decreases the thermal efficiency due to uneven heat distribution and incomplete startup. Orientation studies show that the inclination of the DE-LHP reduces the liquid carryover and vapor backflow, improving the heat transfer efficiency. These findings provide valuable insights for optimizing the DE-LHP design and improving the thermal management system.

{"title":"Experimental investigation on the startup behavior and visualization of dual-evaporator loop heat pipes","authors":"Andhy M. Fathoni , Priska A. Hendrayanto , Ranggi S. Ramadhan , Nandy Putra","doi":"10.1016/j.ijheatmasstransfer.2025.127053","DOIUrl":"10.1016/j.ijheatmasstransfer.2025.127053","url":null,"abstract":"<div><div>This study investigates the startup behavior and flow dynamics of a dual-evaporator loop heat pipe (DE-LHP) using neutron radiography. The DE-LHP is designed to overcome the challenges of efficiently managing multiple heat sources. Neutron radiography allows visualization of the liquid and vapor distributions, revealing phenomena like vapor backflow, liquid carryover, and heat leakage. Experiments were conducted with various heat load configurations, including balanced and unbalanced distributions, and different geometric orientations. The results show that at a balanced heat load (120 W total), the system reaches steady-state in 500 s with a thermal resistance of 0.14 °C/W while the highest thermal resistance of 0.64 °C/W was observed in the unequal heat load case of 56 W. The unbalanced heat load increases the thermal resistance and decreases the thermal efficiency due to uneven heat distribution and incomplete startup. Orientation studies show that the inclination of the DE-LHP reduces the liquid carryover and vapor backflow, improving the heat transfer efficiency. These findings provide valuable insights for optimizing the DE-LHP design and improving the thermal management system.</div></div>","PeriodicalId":336,"journal":{"name":"International Journal of Heat and Mass Transfer","volume":"246 ","pages":""},"PeriodicalIF":5.0,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799181","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}

引用次数: 0