毛细芯微槽蒸发器微型化过程的极限工况预测

Critical conditions prediction on capillary micro-groove evaporator by the device miniaturization

在汽-液两相混合模型基础上,对汽-液交界面附近两相过渡区的毛细力进行表征,建立了毛细芯微槽蒸发器的三维稳态轴对称单元模型。同时,以界面热流密度和入口供液流量作为变工况参数,划分得到4种典型工况区间,并预测分析了蒸发器微型化过程的流动-传热极限特性。结果表明,当热流密度一定时,随着微型化比例减小,3条临界流量线呈交汇趋势,对应的两相安全区流量变化范围不断缩小,且极限控温温度对应的液面相对高度显著降低,液面逼近毛细芯下界面;当入口供液流量一定时,随着微型化比例减小,两相安全区热流密度变化范围几乎不变,且极限控温温度对应的液面相对高度维持在毛细芯2/3高度处。研究结论为毛细芯微槽蒸发器的微型化结构设计及其工况参数选择提供了理论参考。

Based on vapor-liquid two-phase hybrid model,the capillary force in two-phase transition region near vapor-liquid interface was characterized,and a three-dimensional steady-state axisymmetric model of the calculation element for the capillary micro-groove evaporator was established.Besides,with heat flux load on device interface and inlet liquid supply flow rate as variable operating parameters,four kinds of typical operation intervals were obtained.Additionally,the ultimate flow and heat transfer characteristics by the device miniaturization were predicted.The results show that,under the same heat flux condition,with the decrease of miniaturization ratio,three critical flow lines have the trend of convergence,and the flow range in two-phase safety region is shrinking.The relative height of vapor-liquid interface corresponding to the limit control temperature decreases significantly and the interface approaches the lower border of the capillary wick.Under the same liquid supply flow condition,with the decrease of miniaturization ratio,the heat flux range in two-phase safety region is almost unchanged,and the relative height of vapor-liquid interface corresponding to the limit control temperature is maintained at 2/3 height of the capillary wick.The conclusion of the study will provide theoretical reference on the miniaturization design and selection of optimum operating parameters.