Effects of surface characteristics on liquid behaviors on fin surfaces during frosting and defrosting processes

Liquid behaviors on fin surfaces include droplets condensation during the initial stage of frosting process and molten water retention during defrosting process. In this paper, three types of fins (hydrophilic, bare and super hydrophobic fins) were prepared and the effects of surface characteristics on liquid behaviors were investigated experimentally. Condensate droplets were observed on the bare fin firstly while on the super hydrophobic fin lastly. The effects of surface characteristics on shapes and distribution density of condensate droplets were significant. The fractions of surface covered area were 91%, 63% and 15% for hydrophilic, bare and super hydrophobic fins, respectively. Retained water formed a thin water film on the hydrophilic fin, while only a few spherical droplets with small sizes stayed on the super hydrophobic fin because the frost layer directly released from it. The retained water mass on the super hydrophobic fin decreased by 79.82% and 65.63% compared with those of the other two fins. Moreover, the effects of surface characteristics on liquid behaviors were analyzed theoretically. Experimental and theoretical results indicate that the super hydrophobic fin can restrain droplets condensation and molten water retention. (C) 2014 Elsevier Inc. All rights reserved.