Effect of surface wettability on dust removal characteristics during frosting cleaning process

Utilizing the frosting-defrosting process for dust removal is a simple and novel method to keep heat exchangers clean. With the development of surface treatment technology, the effect of the wettability of a surface on cleaning effects has drawn great attention. As the dynamic behavior of the frost layer varies with surfaces wettability, the interaction between the dust layer and frost layer also varies. Through experiments on four kinds of copper surfaces, we studied the effect of surface wettability on dust removal characteristics during the frosting cleaning process. The four surfaces were: bare surface, hydrophilic surface, super-hydrophobic surface, and sliding surface. The results show that dust particles get removed with the movement of the melted water on the hydrophilic, bare and sliding surfaces, whereas on the super-hydrophobic surface, dust particles get wrapped into the curling frosting layer and fall with chunks of frost-water mixture. The dust removal rates during the frosting cleaning process were 24.1%, 28.1%, 86.6%, and 32.7% on the four kinds of surfaces. The super-hydrophobic surface has a shorter defrosting time and exhibits the wrapping effect of the dust layer, which gives it the optimal dust removal property. The sliding surface is also promising in the dust removal applications.