Article
Thermodynamics
Zhengang Zhao, Guohong Peng, Yanhui Zhang, Dacheng Zhang
Summary: In this paper, a novel sintered multi-size copper powder wick is designed and experimentally investigated for heat flux management. The results show that the new wick has shorter liquid transfer time, faster dynamic response time, and lower overall thermal resistance compared to single-size copper powder wicks.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Shwin-Chung Wong, Mao-Shen Deng, Min-Chieh Liu
Summary: This study investigates the capillary properties of a flat-plate heat pipe with a sintered composite copper mesh-groove wick and proposes a new formula for calculating its permeability. The experimental results show that the composite mesh-groove wick has a higher maximum heat load compared to another commonly used wick.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Yugao Ma, Yingnan Zhang, Hongxing Yu, G. H. Su, Shanfang Huang, Jian Deng, Xiaoming Chai, Xiaoqiang He, Zhuohua Zhang
Summary: Screen-wick heat pipes are efficient passive heat transfer devices with heat transfer capacity determined by capillary pressure and film curvature. A capillary evaporating film model was developed, showing improved prediction of the liquid film characteristics. The wire opening distance and diameter affect capillary pressure and flow path. This work provides reference for operating alkali-metal wick heat pipes.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Prem Kumar, Mayur Gachake, Sameer Khandekar
Summary: The study focuses on reducing heat leak in loop heat pipes (LHP) by manipulating the properties of the copper wick, leading to improved thermal performance. It was found that the oxidized copper wick performs better thermally than the pure copper wick, attributed to the lower thermal conductivity of the oxidized porous wick reducing heat leak.
APPLIED THERMAL ENGINEERING
(2022)
Article
Engineering, Mechanical
Jong Hyeon Son, Arun Raj Shanmugam, Dong-Eun Lee, Sang Ryong Lee, Il Seouk Park
Summary: This study investigates the hydrothermal characteristics of a capillary-driven stepped heat pipe (SHP). Through axisymmetric numerical simulation, the effects of step pattern, area ratio (AR), evaporator length (LE), and wick parameters on the system characteristics are analyzed. The numerical results agree well with literature data. The study suggests that a two-sided step and a step with sudden contraction and enlarged evaporator can achieve superior performance. SHPs with a large AR and long evaporator exhibit better thermal and capillary performances, while those with a small condenser diameter are more prone to dryout. The wick parameters, such as porosity and wick type, play a vital role in the system performance. The numerical results provide clear engineering guidance for the design of SHPs in various engineering applications.
JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY
(2023)
Article
Thermodynamics
Shwin-Chung Wong, Mao-Shen Deng
Summary: Two types of novel triple composite mesh-groove-powder wicks were proposed and tested in a flat-plate heat pipe. The results showed that the powders in the mesh-groove evaporator increased flow resistance and caused partial dry-out in some grooves at high heat loads, but the powder-only evaporator improved the heat load.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jie Zhao, Yang Ji, Da-Zhong Yuan, Yu-Xiang Guo, Shui-Wen Zhou
Summary: This study proposes a composite wick to optimize the anti-gravity heat transfer performance of a concentric annular high temperature heat pipe. The experimental results show that the dense pore-sparse pore-dense pore screen combination can achieve stable anti-gravity operation, and the composite wick has an impact on the anti-gravity heat transfer performance of the heat pipe.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Samet Saygan, Yigit Akkus, Zafer Dursunkaya, Barbaros Cetin
Summary: This study demonstrates the enhanced heat pipe performance through capillary boosting with the introduction of groove bifurcation. Experimental results show that heat pipes with groove bifurcation can provide better heat transport capacity than standard grooved heat pipes, with at least 25% higher maximum heat transport capacity.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2022)
Article
Thermodynamics
Soosik Bang, Jeonghwan Kim, Seunggeol Ryu, Seokkan Ki, Yun Jung Heo, Choongyeop Lee, Youngsuk Nam
Summary: We developed asymmetric capillary wicks using inclined photolithography, and studied the effects of inclination angle and wicking direction on capillary and heat transfer performances. The capillary performance was improved by up to 39% with forward flow and decreased by 21.3% with reverse flow. The heat transfer performance test showed that the wick-CHF of the asymmetric forward flow case was increased by 43.3% while maintaining the heat transfer coefficient. This work demonstrates the potential of asymmetric evaporator wicks for enhancing critical heat flux without sacrificing heat transfer coefficient, which can contribute to the development of high-performance thermal management solutions.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Feng Yi, Yunhua Gan, Zhifeng Xin, Yong Li, Hanyin Chen
Summary: In this study, a novel double-layer wick structure consisting of sintered copper powder and spiral woven mesh was proposed to improve the thermal performance of ultra-thin heat pipes. The results showed that the double-layer wick structure exhibited an 11.1% increase in ultimate power compared to the single wick structure.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2023)
Article
Thermodynamics
Jui-Cheng Yu, Heng-Chieh Chien, Chao-Yang Chiang, En-Chia Liu, Yu-Hsiang Chang, Hung-Hsien Huang, Tang-Yuan Chen, Chin-Li Kao, Chien-Neng Liao
Summary: This study examines the capillary performance of a porous Cu wick structure fabricated using a new electrodeposition process. The morphology of the dendritic Cu deposits can be adjusted to effectively enhance the capillary wick performance. The thermally treated Cu wick shows excellent capillary performance and structural stability, which is important for high-density and large-area heat dissipation applications.
APPLIED THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Heng Tang, Changxing Weng, Yong Tang, Hui Li, Teng Xu, Ting Fu
Summary: The study proposed a high-performance multiple mesh wick structure fabricated by oxidation treatment and sintering to enhance the thermal performance of UFHPs. The experimental results demonstrated that oxidation treatment effectively enhanced the heat-transport capability of the UFHP with the mesh wick, showing the same capillary performance as sintered powder wicks. Additionally, the performance improvement of the UFHP with the mesh wick was more significant after treatment with chemical oxidation, especially with larger flattened thicknesses.
APPLIED THERMAL ENGINEERING
(2021)
Article
Engineering, Aerospace
Tao Yang, Teng Gao, Shilei Zhao, Ping Zhang
Summary: This paper presents a novel flat capillary pump to enhance the reliability of start up and operation under anti-gravity and microgravity conditions. The experimental results demonstrate that the pump performs well in different orientations and heat loads.
MICROGRAVITY SCIENCE AND TECHNOLOGY
(2022)
Article
Thermodynamics
Shen -Chun Wu, Zhan-Hui Lin, Shu Lo, Wei-Jhih Lin
Summary: Changing the thickness of the polymer wick can effectively reduce heat leakage in the heat pipe, and a thickness of 2mm achieves the best performance.
THERMAL SCIENCE AND ENGINEERING PROGRESS
(2023)
Article
Thermodynamics
Kangning Xiong, Shuangfeng Wang
Summary: In this work, a low thermal conductivity and high capillary performance porous mullite ceramics secondary wick was prepared to effectively reduce heat leakage in the evaporator of a loop heat pipe (LHP). The addition of NaHCO3 powder improved the compressive strength and porosity of the ceramics, while the surface structure of the ceramics enhanced the capillary performance. Compared to sintered porous copper powder, the porous mullite ceramics exhibited higher porosity, lower thermal conductivity, and superior capillary rise height.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Mahsa Taghavi, Swapnil Sharma, Vemuri Balakotaiah
Summary: This study investigates the natural convection effects in the insulation layers of spherical storage tanks and their impact on the tanks' performance. The permeability and Rayleigh number of the insulation material are considered as key factors. The results show that as the Rayleigh number increases, new convective cells emerge and cause the cold boundary to approach the external hot boundary. In the case of large temperature differences, multiple solutions may coexist.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyang Xu, Fangjun Hong, Chaoyang Zhang
Summary: This study introduces a self-induced jet impingement device for enhancing pool boiling performance in high power electronic cooling. Through visualization and parametric investigations, the effects of this device on pool boiling performance are studied, revealing the promotion of additional liquid supply and vapor exhausting. The flow rate of the liquid jet is found to positively impact boiling performance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Wenchao Ke, Yuan Liu, Fissha Biruke Teshome, Zhi Zeng
Summary: Underwater wet laser welding (UWLW) is a promising and labor-saving repair technique. A thermal multi-phase flow model was developed to study the heat transfer, fluid dynamics, and phase transitions during UWLW. The results show that UWLW creates a water keyhole, making the welding environment similar to in air laser welding.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Xingrong Lian, Lin Tian, Zengyao Li, Xinpeng Zhao
Summary: This study investigates the heat transfer mechanisms in natural fiber-derived porous structures and finds that thermal radiation has a significant impact on the thermal conductivity in low-density regions, while natural convection rarely occurs. Insulation materials derived from micron-sized natural fibers can achieve minimum thermal conductivity at specific densities. Strategies to lower the thermal conductivity include increasing porosity and incorporating nanoscale pores using nanosize fibers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Yasir A. Malik, Kilian Koebschall, Stephan Bansmer, Cameron Tropea, Jeanette Hussong, Philippe Villedieu
Summary: Ice crystal icing is a significant hazard in aviation, and accurate modeling of sticking efficiency is essential. In this study, icing wind tunnel experiments were conducted to quantify the volumetric liquid water fraction, sticking efficiency, and maximum thickness of ice layers. Two measurement techniques, calorimetry and capacitive measurements, were used to measure the liquid water content and distribution in the ice layers. The experiments showed that increasing wet bulb temperatures and substrate heat flux significantly increased sticking efficiency and maximum ice layer thickness.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinqi Hu, Tongtong Geng, Kun Wang, Yuanhong Fan, Chunhua Min, Hsien Chin Su
Summary: This study experimentally examined the heat dissipation of vibrating fans and demonstrated its inherent mechanism through numerical simulation. The results showed that the flow fields induced by the vibrating blades exhibited pulsating features and formed large-scale and small-scale vortical structures, significantly improving heat dissipation. The study also identified the impacts of different blade structures and developed a trapezoidal-folding blade, which effectively reduced the maximum temperature of the heat source and alleviated high-temperature failure crisis.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Dan-Dan Su, Xiao-Bin Li, Hong-Na Zhang, Feng-Chen Li
Summary: The boiling heat transfer of low-boiling-point working fluid is a common heat dissipation technology in electronic equipment cooling. This study analyzed the interfacial boiling behavior of R134a under different conditions and found that factors such as the initial thickness of the liquid film, solid-liquid interaction force, and initial temperature significantly affect the boiling mode and thermal resistance.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Jinyi Wu, Dongke Sun, Wei Chen, Zhenhua Chai
Summary: A unified lattice Boltzmann-phase field scheme is proposed to simulate dendrite growth of binary alloys in the presence of melt convection. The effects of various factors on the growth are investigated numerically, and the model is validated through comparisons and examinations.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shaokun Ge, Ya Ni, Fubao Zhou, Wangzhaonan Shen, Jia Li, Fengqi Guo, Bobo Shi
Summary: This study investigated the temperature distribution of main cables in a suspension bridge during fire scenarios and proposed a prediction model for the maximum temperature of cables in different lane fires. The results showed that vehicle fires in the emergency lane posed a greater thermal threat to the cables.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Shuang-Ying Wu, Shi-Yao Zhou, Lan Xiao, Jia Luo
Summary: This paper investigates the two-phase flow and heat transfer characteristics of low-velocity jet impacting on a cylindrical surface. The study reveals that the heat transfer regimes are non-phase transition and nucleate boiling with the increase of heat transfer rate. The effects of jet impact height and outlet velocity on local surface temperatures are pronounced at the non-phase transition stage. The growth rates of heat transfer rate and liquid loss rate increase significantly from the non-phase transition to nucleate boiling stage.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Emad Hasani Malekshah, Wlodzimierz Wlodzimierz, Miros law Majkut
Summary: Cavitation has significant practical importance and can be controlled by air injection. This study investigates the natural to ventilated cavitation process around a hydrofoil through numerical and experimental methods. The results show that the location and rate of air injection have a meaningful impact on the characteristics of cavitation.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Feriel Yahiat, Pascale Bouvier, Antoine Beauvillier, Serge Russeil, Christophe Andre, Daniel Bougeard
Summary: This study explores the enhancement of mixing performance in laminar flow equipment by investigating the generation of chaotic advection using wall deformations in annular geometries. The findings demonstrate that the combined geometry can achieve perfect mixing at various Reynolds numbers.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Hui He, Ning Lyu, Caihua Liang, Feng Wang, Xiaosong Zhang
Summary: This study investigates the condensation, frosting, and defrosting processes on superhydrophobic surfaces with millimeter-scale structures. The results reveal that the structures can influence the growth and removal of frost crystals, with the bottom grooves creating a frost-free zone and conical edges promoting higher frost crystal heights. Two effective methods for defrosting are observed: hand-lifting the groove and airfoil retraction contraction on protruding structures. This research provides valuable insights into frost formation and defrosting on millimeter-structured superhydrophobic surfaces, with potential applications in anti-frost engineering.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Thiwanka Arepolage, Christophe Verdy, Thibaut Sylvestre, Aymeric Leray, Sebastien Euphrasie
Summary: This study developed two thermal concentrators, one with a 2D design of uniform thickness and another with a 3D design, using the coordinate transformation technique and metamaterials. By structuring the thermal conductor, the desired local density-heat capacity product and anisotropic thermal conductivities were achieved. The homogenized thermal conductivities were obtained from finite element simulations and cylindrical symmetry consideration. A 3D concentrator was fabricated using 3D metal printing and characterized using a thermal camera. Compared to devices that solely consider anisotropic conductivities, the time evolution characteristics of the metadevice designed with coordinate transformation were closer to those of an ideal concentrator.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Thermodynamics
Liangyuan Cheng, Qingyang Wang, Jinliang Xu
Summary: In this study, we investigated the supercritical heat transfer of CO2 in a horizontal tube with a diameter of 10.0 mm, covering a wide range of pressures, mass fluxes, and heat fluxes. The study revealed a non-monotonic increase in wall temperatures along the flow direction and observed both positive and negative wall temperature differences between the bottom and top tube. The findings were explained by the thermal conduction in the solid wall interacting with the stratified-wavy flow in the tube.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)