基于杨氏理论的微型换热器传热壁面表面特性分析

Analysis of Heat Transfer Channel Surface Characteristic of Micro Heat Exchanger Based on Young's Theory

微型换热器换热通道壁面的表面特性对流体流动沸腾特性有显著的影响.固体表面能常被用来表征微型换热器换热通道壁面的表面特性,可为微细通道中流体流动沸腾特性的研究提供理论依据;文中测量去离子水、乙二醇、甲酰胺在换热通道内侧左右壁面及底表面所形成的接触角,基于杨氏理论计算微型换热器换热壁面的表面能,并通过液滴的Wenzel模型分析微槽道内、外表面接触角差异形成的机理.研究结果表明:微型换热器换热通道内侧左、右壁面的表面能分别为5.2、5.6 MJ/m2,底表面的表面能为8.2 MJ/m2,微细通道内表面特性差异是由表面粗糙度不同造成的.

The surface characteristic of the heat transfer channel of micro heat exchangers has a significant effect on the flow boiling performance of fluid. Solid surface energy is often used to describe the surface characteristics of the heat transfer channel, which can provide a theoretical basis for the research of the flow boiling performance of the fluid in micro-channels. In the investigation, the contact angles of deionized water, ethylene glycol and formamide with the left, right and bottom surfaces of the heat transfer channel were measured respectively, and the solid sur-face energy of the heat transfer channel was calculated on the basis of Young^ theory. Then, the forming mechanism of the contact angle difference between the inside and outside surfaces of the micro-channels was analyzed through the Wenzel model of droplet. The results show that the solid surface energy of the left, right and bottom surfaces of the heat transfer channel are respectively 5.2, 5.6 and 8.2MJ/m^2, and the surface roughness difference causes the inside surface features to be different.