自然对流条件下仿生超疏水表面的抑霜研究

FROST FORMATION ON A BIONIC SUPER-HYDROPHOBIC SURFACE UNDER NATURAL CONVECTION CONDITIONS

仿生超疏水表面具有多重纳米和微米级的超微结构,其与水滴的接触角一般在150度以上,本文将这种仿生超疏水表面应用到制冷抑霜实验中,观察其表面上水珠的生成、冻结、初始霜晶的出现以及最终霜晶的特殊形态,与普通金属表面上霜的形成过程相比,这种表面具有很强的抑霜性,在-10℃的冷表面上它能延迟初始霜晶的形成55 min以上,其最终形成的霜晶结构松散,较易去除。在实验中首次发现了在该表面上形成的霜晶形态特异,类似一朵朵菊花。最后本文从理论上分析了这种表面的抑霜机理。

Bionic super-hydrophobic surface has a multiple micro-nano-binary structure （MNBS） similar to the microstructure shown on a lotus leaf. This kind of the surfaces has a contact angle of water greater than 150° and a roll angle smaller than 5°. In this paper, the frost deposition phenomena on a bionic super-hydrophobic surface were observed. The surface has a 159° contact angle and is made of many micro bumps. The formation of water droplets, the droplet freezing process, the formation of initial frost crystals and the frost layer structure on a cold bionic super-hydrophobic surface under natural convection conditions were closely observed. The frost layer structure on the super-hydrophobic surface shows remarkable differences to that on a plain copper surface： the structure is weaker, looser, thin and easy to be removed and most importantly, it is of a very special pattern, a pattern similar to chrysanthemum, a frost layer structure that has not been reported before as far as the present authors could know. The experimental results also show that the super-hydrophobic surface has a strong ability to restrain frost growth. The frost deposition on this bionic surface Was delayed for 55 min compared with the plain copper surface under the conditions of a cold plate temperature -10.1℃, air temperature 18.4℃ and relative humidity 40%. A theoretical analysis was also presented to explain the observed phenomena.