Experimental Investigation on Evaporator Surface Modification for Hydrophobicity and Frost Resistance

Frost accumulated on the surface of the evaporator leads to the increase of heat transfer resistance between the refrigerant and environmental medium, which reduces the system performance of cold storage and air source heat pump. To solve this problem, the surface-modified evaporator can achieve retardation of the frost formation, which greatly improves the heat exchange effect between the refrigerant and the external environment. In this paper, a novel coating sprayed on the evaporator was developed using the sol-gel method and the hydrophobicity, durability, and thermal conductivity were investigated. Moreover, a modified method of frost weight measurement under different temperatures and humidity was first proposed. The results showed that the coating has a favorable hydrophobic effect and thermal conductivity, and long service life. Under the standard experimental condition, the frost weight on the coating surface can be reduced up to 26.1 %. Additionally, the effect of coating composition ratio on its performance was further investigated. To sum up, this new coating has the potential for industrialized application.