Article
Thermodynamics
Qifan Li, Zhong Lan, Jiang Chun, Shijun Lian, Rongfu Wen, Xuehu Ma
Summary: A novel micro-grooved wick with multi-scale structures was fabricated and its capillary performance investigated, showing that microstructure features had minimal effect on permeability and composite wick covered by microcavities exhibited superior capillary pumping amount and wicking velocity. In the comprehensive evaluation, the optimized capillary wick with microcavities showed over 260% improvement in capillary performance compared to plain sintered-powder wicks.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2021)
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
Xueqing Li, Dongxu Yao, Kaihui Zuo, Yongfeng Xia, Yu-Ping Zeng
Summary: Porous Si3N4 ceramics with monomodal and bimodal pore size distribution are selected for loop heat pipe wick materials. Tailoring the pore structures influences capillary and thermal performance, with wicks showing larger permeability having lower filling coefficients and better capillary performance. Wicks using working fluids with specific properties exhibit better capillary performance, and effective thermal conductivity is determined by total porosity.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Chemistry, Physical
Im-Nam Jang, Yong-Sik Ahn
Summary: The porosity, permeability, and capillary force of porous sintered copper were studied in relation to copper powder size, pore-forming agent, and sintering conditions. Higher values of porosity and permeability were observed when the copper powder size was uniform or small. The capillary force increased with the addition of more forming agent and was higher with larger and non-uniform copper powder size. The results were discussed in relation to porosity and pore size distribution.
Article
Thermodynamics
Jing Zhang, Li-xian Lian, Ying Liu, Ren-quan Wang
Summary: In this study, the capillary limit of heat pipes was predicted based on capillary rise test, showing that irregular powders outperform spherical powders but the experimental values were approximately 7 to 11W higher than the predicted values. The experimental capillary limit was used to adjust the prediction equation at different working temperatures.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Materials Science, Multidisciplinary
Yingwen Cao, Chunsheng Guo, Dongting Wu, Yong Zou
Summary: A bi-porous Ti3AlC2 wick was produced by reaction sintering and pore formers dissolution, with porosity and pore size being regulated by varying pore formers content and cold pressure. Increasing pore formers content led to an increase in the proportion of large pores and overall porosity, enhancing capillary performance and reducing thermal conductivity. Higher cold pressure resulted in a concentrated pore size distribution, an increase in fine pores proportion, and slight fluctuations in porosity, ultimately increasing capillary pressure, improving capillary performance, and enhancing thermal conductivity.
MATERIALS RESEARCH EXPRESS
(2021)
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
Materials Science, Multidisciplinary
Trinh Minh Hoan, Nguyen Van Toan, Nguyen Phu Hung, Pham Van Trinh, Tran Bao Trung, Doan Dinh Phuong
Summary: Permeability and capillary performance, which are important parameters for heat pipes, are affected by the particle size and geometry of copper powder. The porosity and capillary performance of sintered porous wicks made from different-sized spherical and dendritic Cu powders were studied. The results showed that both types of copper powder had higher porosity and capillary performance with larger particle size, due to increased connectivity between internal pores. The dendritic powder exhibited superior capillary efficiency and porosity compared to the spherical powder. A model was also proposed to predict the capillary performance and permeability of sintered porous copper.
Article
Thermodynamics
Srivathsan Sudhakar, Justin A. Weibel, Suresh Garimella
Summary: Two-phase passive heat transport devices use porous evaporators for phase change and fluid transport. This study presents a new semi-empirical model for predicting thermal resistance and dryout during boiling in capillary-fed evaporators. The model considers thermal conduction, volumetric evaporation, and capillary-driven liquid flow to obtain temperature distribution and local pressures within the porous structure. The model successfully predicts trends in dryout limit with particle size, heater size, and evaporator thickness.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Thermodynamics
Yuankun Zhang, Zhuosheng Han, Zihang Zhu, Yongsheng Yu, Yiming Gao, Chunsheng Guo
Summary: Loop heat pipes (LHPs) play an important role in managing thermal conditions in critical electronic components of spacecraft and satellites. This study establishes an efficient procedure for predicting the effective thermal conductivity (ETC) in bi-porous wicks and highlights the valuable contributions of both analytical and numerical methods in evaluating ETC of sintered bi-porous structures.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Thermodynamics
Tingting Miao, Zhengyang Liu, Dongsheng Chen, Meng An, Weigang Ma
Summary: This study proposes a capillary wick material based on carbon nanotube arrays, which can regulate its heat transfer performance by controlling the water filling ratio. Molecular dynamics simulation results show that the thermal conductivity of water-filled carbon nanotubes is reduced, which is beneficial for start-up operation. In addition, empty carbon nanotubes have high thermal conductivity and can reduce the temperature of the endothermic surface.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Chemistry, Physical
Danny Kojda, Tommy Hofmann, Natalia Gostkowska-Lekner, Klaus Habicht
Summary: This study synthesized nanostructured silicon and silicon-aluminum compounds using spark plasma sintering technology, and the interplay of metal-assisted crystallization and inherent porosity is used to suppress thermal conductivity. The research found that porosity and nanostructure have a significant impact on macroscopic heat transport.
Article
Materials Science, Ceramics
Sawao Honda, Shinobu Hashimoto, Benoit Nait-Ali, David S. Smith, Yusuke Daiko, Yuji Iwamoto
Summary: Highly textured porous alumina was successfully fabricated using pulse electric current sintering (PECS) method, and its properties were measured in two directions. It was found that the porosity and thermal conductivity of the porous alumina varied along different directions, and the bending strength and thermal shock strength also showed significant differences in the two directions.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2022)
Article
Thermodynamics
Miao Liu, Wenjing Ning, Junbo Yang, Yuankun Zhang, Zhuosheng Han, Ge Meng, Chunsheng Guo, Han Lin, Baohua Jia
Summary: This study proposes a novel composite pore former comprising NaCl and g-C3N4 for fabricating high-performance multi-morphology porous wicks. The synergistic effect of these pores increases the wicks' porosity and reduces flow resistance, enabling them to exhibit high comprehensive performance. The wicks also have ultralow thermal resistance and exceptional anti-gravity performance.
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
(2023)
Article
Thermodynamics
Munonyedi Egbo, Jacob Keese, Gisuk Hwang
Summary: This study investigates the enhanced wickability using bi-particle-size, sintered-particle wicks in two-phase thermal management systems. The results show that the bi-particle-size wicks significantly improve permeability and therefore cooling performance compared to uniform particle wicks.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
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)