毛细管内薄液膜轮廓和传热特性研究

INVESTIGATION ON CHARACTERISTICS OF THIN FILM PROFILE AND HEAT TRANSFER IN MICRO CAPILLARY TUBES

本文认为毛细管的相变传热机理为液膜的导热和表面蒸发；表面蒸发受蒸汽温度、汽液界面的温度以及汽液压力差的共同控制。汽液流动机理为流动受脱离压力梯度、毛细力梯度支配。汽液相互作用机理为存在由于蒸发导致的动量转移切应力和由于汽液流速不同产生的摩擦切应力。提出的物理模型中较为全面地考虑了毛细管内传热、汽液流动及其相互作用。对毛细管半径和传热功率对薄液膜轮廓和传热特性影响程度的计算结果表明，随着毛细管半径的减小、传热功率的增大，蒸发界面区的长度会有所减小，这是针对微小空间得出的不同于常规情况的结论。

In this paper, it is believed that the heat transfer mechanism of phase change in a capillary tube belongs to liquid film conduction and surface evaporation. The surface evaporation is influenced by vapor temperature, vapor-liquid interfacial temperature and vapor-liquid pressure difference. The vapor-liquid flow mechanism is that flow is effected by gradient of disjoining pressures gradient of capillary pressure. The mechanism of vapor-liquid interaction consists of shear stress of momentum transfer owing to evaporation, and frictional shear stress due to the velocity difference of vapor and liquid. In the presented model for a capillary tube, the heat transfer, vapor-liquid flow and their interaction are more comprehensively considered. The thin film profile and heat transfer characteristics have close relations with capillary radius and heat transfer power. The calculation results indicate that with the capillary radius decreasing, the heat transfer power increasing, the length of the evaporating interfacial region will decrease to some extent. This is the conclusion for micro space different from that of conventional situation.