Experimental study of frosting cleaning process on superhydrophobic copper surface

Frosting cleaning process for dust removal is a simple and direct way to keep heat exchangers clean, and the dust removal effectiveness is strongly influenced by surface property. An object of this paper is to investigate the frosting cleaning process on super-hydrophobic surface and to determine the interaction between the frost layer and dust particles. Frosting-defrosting process on four kinds of test samples were studied by experiments. The results showed that, compared with the clean surfaces, the frost layer structure was denser and more uniform on dusty surfaces. On the super-hydrophobic surface, as a kind of heterogeneous nucleation point, the dust particle promoted frost layer growth by 57%. During the defrosting process on dusty test samples, the melted water and dust particles were reverse osmosed the frost layer. The reverse osmosed rate increased with frosting time, and it was over 0.5 under all experimental conditions. Compared with the bare surface, super-hydrophobic surface displayed a different defrosting behavior and had a shorter defrosting time. On the super-hydrophobic surface, deposited dust particles were encased in the frost-water mixture block and flaked off the surface under gravity, and the dust removal rate was up to 94.5% in this work. Because of the reverse osmosed dust movement, the wrap effect, and the weak adhesion of super-hydrophobic surface, the dust-frost mixture is easily removed. Thus, utilizing the frosting-defrosting characteristics of super-hydrophobic surface for promoting the dust removal has a good application prospect.