摘要
为揭示方肋微通道热沉内流动沸腾的传热传质机理,本文基于耦合VOF方法与“饱和界面”相变模型对微通道内单个气泡绕流加热方肋的传热传质过程进行了数值研究。通过分析该过程中气泡增长速率与方肋壁面传热系数的变化,重点讨论了初始气泡体积和入口雷诺数Re对相变传热效率和流动结构的影响。结果表明:在气泡流经加热方肋过程中,气泡与方肋表面之间形成一层薄液膜,该薄液膜的相变蒸发极大强化方肋表面的换热效果,换热系数较相同条件下的单相流动提升6倍以上。此外液膜厚度随Re增大而变厚,液膜热阻相应增大,液膜蒸发对换热的促进作用随Re增大而降低。最后考察了气泡体积对方肋壁面换热的影响,结果表明:初始体积大的气泡具有更薄的液膜厚度及更大的蒸发面积,表现出更高的相变传热效率;而小气泡对壁面温度影响较小。
In order to understand the mechanisms of heat and mass transfer enhancement of flow boiling in square-fin based microchannel heat sinks,volume of fluid(VOF)method coupled with the saturated interface volume phase change model were used to simulate the phase change heat transfer from a single bubble traveling past a heated square cylinder in a microchannel.By comparing the bubble volume growth rate and heat transfer from the square cylinder during the evaporation process,the effects of the initial bubble volume and Reynolds number on the heat and mass transfer in the vicinity of the cylinder were analyzed,respectively.The results showed that a thin liquid film trapped between the bubble and the cylinder wall was formed during the bubble transit,which significantly enhanced the heat transfer coefficient on the top face of cylinder by as much as six times higher than the liquid-only value due to the thin-film evaporation.The thermal resistance of liquid film was increased due to a thicker film for sufficiently large Re,which lowered the heat transfer enhancement.Furthermore,the effect of bubble volume on the heat transfer performance in the square fin was investigated.The results showed that the overall enhancement of heat transfer coefficient along the cylinder was found to increase with increasing bubble volume due to a thinner film and more surface area for evaporation,while the small bubble had little effect on the wall temperature.
作者
申宇
潘振海
吴慧英
SHEN Yu;PAN Zhenhai;WU Huiying(School of Mechanical Engineering,Shanghai JiaoTong University,Shanghai 200240,China)
出处
《化工进展》
EI
CAS
CSCD
北大核心
2020年第7期2548-2555,共8页
Chemical Industry and Engineering Progress
基金
国家自然科学基金(51820105009,51536005,51706136)
上海高校特聘教授(东方学者)岗位计划。
关键词
微通道
流动沸腾
强化换热
气液两相流
数值模拟
microchannels
flow boiling
enhanced heat transfer
gas-liquid flow
numerical simulation
