表面纳米结构及其自由能对滴状冷凝传热的影响

EFFECT OF SURFACE NANOSTRUCTURE AND SURFACE FREE ENERGY ON DROPWISE CONDENSATION HEAT TRANSFER

通过抛光和氧化刻蚀方法在基体壁面形成微米和纳米尺度的微观结构,然后制备十八烷基硫醇分子自组装膜,从而得到空气中表观接触角为160°的SAM-1表面和空气中表观接触角为116°的SAM-2表面。实验研究了常压条件下两类表面的滴状冷凝传热特性。结果表明两种表面都能够有效提高冷凝传热效果。但是,具有表面纳米结构的SAM-1表面的滴状冷凝传热特性低于SAM-2表面。分析了纳米结构和液固自由能差效应对滴状冷凝传热影响的共同作用机理。

Fine polish and oxidation etching method are applied to prepare micro- and nano-structures on copper surfaces. After that, self-assembled monolayers （SAMs） of n-octadecyl mercaptan are coated on. In air circumstance, the contact angle of water on the nano-structured surface （SAM-1） is 160° and that on the finely polished coated surface （SAM-2） is 116°. Both coated surfaces have promoted dropwise condensation very well. The condensation heat transfer performance of the SAM-2 is much better than that of the SAM-1. The coordinated effects of difference of surface free energy between nanostructure and liquid-solid on the dropwise condensation heat transfer are analyzed.