摘要
微通道换热器因其结构紧凑、换热能力高、工质消耗少等优点成为解决微小空间“散热难”问题的有效途径之一,采用多孔材料制作的微通道热沉能够极大地增加换热面体比,因而可以进一步提高其换热能力。本文利用可视化手段对槽道翅片顶部与盖板间留有狭缝、通道截面为矩形(400µm×600µm)的开放型多孔微通道的流动沸腾现象进行实验研究。研究发现,多孔材料表面及内部形成的大量连通孔穴使得通道中核化位点明显增多,观察到的流型除泡状流、弹状流、段塞流外,还有由于开放通道上方存在狭缝所导致的混合分层气泡流。汽化核心密度增加以及混合分层气泡流的出现增强了微通道内的核态沸腾、微对流和微液膜蒸发,从而增强微通道流动沸腾的换热能力并有效降低壁面过热度。
Micro-channel heat exchanger could be used to solve the heat dissipation problem of small size electronic components due to its compact structure,high heat transfer capacity and low consumption of working fluid.Using the porous materials with large surface-to-volume ratio as the substrate can greatly increase the heat transfer performance of heat sink.In this paper,the flow boiling in rectangular(400µm×600µm)porous microchannels with a narrow gap between the fin top and the cover plate was experimentally studied by visualization.It was found that a large number of connected holes of the porous material acted as the nucleation sites during flow boiling.The bubbly flow,plug/slug flow and the mixed stratified bubbly flow was observed.The increased nucleation site density and the occurrence of the mixed stratified bubbly flow enhanced the nucleate boiling,the micro convection and the thin liquid film evaporation,which decreased the wall superheat and improved the heat transfer capability during flow boiling in the open porous microchannel.
作者
孙明美
贾力
银了飞
党超
薛莹丽
SUN Ming-Mei;JIA Li;YIN Liao-Fei;DANG Chao;XUE Ying-Li(Institute of Thermal Engineering,School of Mechanical,Electronic and Control Engineering,Beijing Jiaotong University,Beijing 100044,China;Beijing Key Laboratory of Flow and Heat Transfer of Phase Changing in Micro and Small Scale,Beijing 100044,China)
出处
《工程热物理学报》
EI
CAS
CSCD
北大核心
2022年第1期226-232,共7页
Journal of Engineering Thermophysics
基金
中央高校基本科研业务费专项资金资助2020JBM054
国家自然科学基金青年科学基金项目(No.51706013)。
关键词
多孔材料
微通道
流动沸腾
气泡行为
流型特征
porous materials
microchannel
flow boiling
bubble behaviors
flow pattern characteristics
