基于扩散界面法的热管毛细芯气液界面蒸发过程模拟研究

热管内毛细芯的毛细蒸发传热是其稳态运行时最主要的传热方式。通过对单个毛细芯孔隙内的毛细界面蒸发过程进行模拟，提出了单个毛细芯的膜态蒸发模型。在相场法的基础上，考虑了界面处的马拉格尼效应、热浮力效应、界面处的蒸发相变过程以及蒸汽扩散产生的反作用力，建立了从单个毛细孔内弯液面蒸发的模型。然后将模拟结果与实验结果进行对比，验证了模型的准确性。通过对界面处的蒸发进行敏感性分析，显示在三相接触线附近有一个强烈的热通量区域，该区域沿弯液面产生了较大的温度梯度，导致了表面张力梯度。该表面张力梯度与浮力效应一起在液膜中引起浮力-热毛细对流。模拟结果表明接触角和过热度对蒸发速率均有显著的影响。

Simulation on Vapor-liquid Interface Evaporation Process of Heat Pipe Capillary Core Based on Diffusion Interface Method

In order to conduct heat transfer in heat pipe more effectively, it is more and more necessary to study the phase transition of capillary cores. By simulating the modal evaporation process in pores of a single capillary core, the film evaporation model of a single capillary core was proposed. Based on the phase field method, the model of evaporation from a single capillary bent surface was established by taking into account the Marangoni effect at the interface, the thermal buoyancy effect, the evaporative phase transition process at the interface and the reaction force generated by steam diffusion. Then the simulation results were compared with the experiment to verify the accuracy of the model. By analyzing the evaporation sensitivity at the interface, it is shown that there is a strong heat flux region near the three-phase contact line, which produces a large temperature gradient along the liquid bending level. This results in the surface tension gradient which, together with the buoyancy effect, causes a buoyancyhot capillary convection in the liquid film. The contact angle and superheat have significant influence on the evaporation rate.