Abstract:

Droplets condensation and growth in the early stage of frosting on hydrophobic surfaces was researched under the natural convection condition. A heat transfer and growth model considered noncondensable gas was developed to clear the influences of surface contact angle and surface temperature on droplets growth. The results show that the two main thermal resistances during the droplet growth stage are the conduction thermal resistance inside the droplet and the phase interface thermal resistance, and both the two thermal resistances increase with surface contact angle, so droplets have a lower growth rate on surface with big contact angle. In addition, the droplets grow faster on surfaces with lower temperature, because colder surfaces could cause bigger heat transfer temperature differences.

Key words: surface, condensation, droplet, growth, heat transfer, thermal resistance

摘要：

研究了自然对流条件下疏水表面结霜初期冷凝液滴的生长过程, 建立了考虑不凝气影响的液滴传热及生长模型, 分析了表面接触角和冷面温度对液滴生长的影响。结果表明, 液滴生长过程中的主要热阻为液滴内部导热热阻和相界面热阻, 随着表面接触角的增大, 这两个主要热阻均增大, 因此表面疏水性越好, 液滴生长越缓慢;而由于冷凝传热温差随冷面温度降低而增大, 因此冷面温度越低, 液滴生长越快。

关键词: 表面, 冷凝, 液滴, 生长, 传热, 热阻