CPL蒸发器多孔芯内传热传质的非稳态数值模拟

基于多孔芯内局部热力学平衡的假设，考虑了Brinkman和Forchheimer对Darcy定律的修正模型，针对简化的物理模型中所包含的气液相区域，建立了二维分层饱和多孔介质模型，以甲醇为工质对CPL，蒸发器毛细多孔芯内的传热传质过程进行非稳态数值模拟。在不同的热负荷条件下预测气液分层界面的形状和位置、系统由初态达到稳态过程的持续时间，讨论压力和温度的分布。由两层饱和模型所得到的计算结果可知．CPL系统在启动时，为避免高热流时液体脱离多孔区而发生干涸，宜采用小负荷启动；采用预热器，改善蒸气的出口条件；增加蒸发器入口处的工质的过冷度，有利于增加CPL系统启动过程和变工况时的稳定性。文中分析结论为CPL系统的优化设计提供参考。

The numerical simulation for the unsteady heat and mass transfer process in capillary pumped loops evaporator

The flow in the porous medium is modeled by using the Brinkman Forchheimer extended Darcy model based on the volume averaging of microscopic conservation equations.For the liquid saturated layer and the vapor saturated layer,the two sets of equations coupled with the matching conditions at the liquid vapor interface are developed.The unsteady state calculations with methanol as a working fluids at different heat loads allow us to trace the evolution phases in the porous wick of a CPL evaporator:growth of vapor zones from origin.Detailed results of the evolution of pressure and heat are provided.The results indicate that at the initialization of start up process,the low heat load exerted on the evaporator is suggested in order to avoid the dry out situation in the porous wick.Adopting warm up device to improve the vapor outlet condition in the vapor groove will increase the steady characteristic after start up or with working condition variation.The analysis of evaporator of CPL system based on the numerical calculation will offer an important direction to the CPL design and system optimization.