LAUSR

Abstract The formation and growth of frost in air source refrigeration systems cause degradation of the system’s performance. Super-hydrophobic technology can delay frost growth and it has received much attention. However, only a limited number of studies have investigated the effects of super-hydrophobic surfaces on frost growth. This study therefore investigated the effects of surface characteristics on frost retardation in heat exchangers with various fin pitches. Heat exchangers with bare, hydrophobic, and super-hydrophobic surfaces were tested, and their frost retardation capabilities were evaluated by comparing the time taken for the air flow passage to be blocked. Hydrophobic and super-hydrophobic surfaces delayed the time by an average of 14.4% and 42.0%, respectively, compared to bare surfaces. The effect of surface characteristics on the heat transfer rate and pressure drop of the heat exchanger was also evaluated. Super-hydrophobic surfaces reduced the decrease in the heat transfer rate and increased the pressure drop by 14.4% and 470%, respectively, compared to bare surfaces. For a system that involves repeated frosting and defrosting, it is estimated that the super-hydrophobic surface can increase the average heat transfer rate by approximately 4.8% more than a bare surface.