Experimental study on frosting and defrosting characteristics for inclined cold plates with surface wettability considered

Frost formation is a ubiquitous phase-change phenomenon, which is a nonlinear and complex physical process involving heat and mass transfer. Most of previous studies focused on frosting and defrosting characteristics of cold surfaces at horizontal or vertical angles, indicating that the inclination angle has a significant effect on the dynamic of frosting and defrosting. However, what happens to the frosting and defrosting process at other different inclination angles have not been clarified. In this study, to explore the effects of inclination angles, surface wettability on frosting and defrosting characteristics, three surfaces with different wettability properties including superhydrophobic, superhydrophilic and hydrophilic surfaces were prepared, and a frosting and defrosting experimental platform with adjustable inclination angle from 0 degrees to 180 degrees was built. Experiment results show that the inclination angle was found to impact both frost quality and thickness. For different wettability surfaces, both frost quality and thickness exhibited a rising trend within the 0 degrees similar to 90 degrees range, followed by a decrease within the 90 degrees similar to 180 degrees range. Moreover, the inclination angle has a significant effect on the frost melting process on superhydrophobic and superhydrophilic surfaces. With the increase of the inclination angle, the amount of retained water decreases gradually, and in the interval of 30 degrees similar to 90 degrees, it does not change much, and the quality is the smallest at 180 degrees.