Mechanistic and experimental analysis of frost suppression performance of a superhydrophobic aluminum surface

Abstract

In recent years, a great deal of attention has been paid to the development of superhydrophobic surfaces for frost prevention. In this work, a superhydrophobic aluminum surface (SHS) with a contact angle of 157.6° was obtained via etching for 18 min using a mixed HCl/HF solution followed by modification for 1.5 h with 5 wt% dodecanoic acid ethanol solution. The frost suppression mechanism and the effect of SHS were analyzed. According to the results, the condensation nucleation barrier of water vapor was large, the nucleation density was small, the heat transfer resistance between the droplets and cold surface was low, and the growth rate of frost crystals was slow, all of which led to the frost suppression characteristics of the SHS. The appearance time of condensation droplets on the SHS was on average 162.5 s longer than that on the bare aluminum surface (BAS), and the weight of condensation droplets per unit area on the SHS was 67.5 %−83.6 % of that on the BAS. Besides, at the refrigeration temperature of −11 ℃, the freezing time of droplets on the SHS was recorded to be 28 min later than on the BAS. Finally, the acicular frost on the SHS appeared approximately 80.8 s later than that on the BAS, and the weight of acicular frost per unit area on the SHS was 54.9 %−79.5 % of that on the BAS.