Study on restraining frost growth at initial stage by hydrophobic coating and hygroscopic coating

For finding an effective method of restraining frost growth, the growing processes of frost on the surfaces of normal copper, hydrophobic coating (car wax coating) and hygroscopic coating (glycerol coating) were studied experimentally. The processes were recorded by photography. The quantitative analysis to the experimental images by digital image processing method was conducted. The results indicate that there is evident effect of hydrophobic coating and hygroscopic coating on frost growth at initial stage. Compared to normal copper surface, frost on the hydrophobic coating surface and on the hygroscopic coating surface appears later with lower frost height, sparse distribution and less aggradations of ice crystals. There is no evident effect of hygroscopic coating thickness on frost height. However, there is evident effect of hygroscopic coating thickness on frost height. The thicker the coating is, the effect on frost growth is bigger. Therefore, frost growth can be restrained by both hydrophobic coating and hygroscopic coating at the initial stage of its formation, and application of hydrophobic coating and hygroscopic coating to heat exchanger in refrigeration and air conditioning equipments would be promising.