After traditional thermal defrosting

a great number of water droplets still retain on the surface

which can become the base of secondary frosting and accelerate secondary frosting. Therefore

duly removing retained droplets after defrosting is of great importance. In this paper

the frost melting evolution on a superhydrophobic surface was visually observed and the effects of the surface inclination angle on defrosting droplet drainage from a bare surface and superhydrophobic surface (with a static contact angle of 88.0°and 151.1°respectively) were comparatively analyzed. The experimental results showed that the defrosting droplets

as an ice-water mixture

suspended on asuperhydrophobic surface with a Cassie state during the defrosting process on a horizontal superhydrophobic surface. Two kinds of behaviors

namely

single-film curling and multi-droplets coalescence

can be seen during the defrosting processes

due to a large static contact angle and tiny contact angle hysteresis. Most of defrosting droplets on an inclined superhydrophobic surface can be self-drained accompanied with ice-water mixture rolling and stripping

which differ from the bare surface. When the inclination angle is greater than 30°

the drainage ratio of the superhydrophobic surface can reach more than 90%

while that of the bare surface can only reach 70%. Furthermore

mechanical analysis of droplets on an inclined surface was applied. The critical droplet-slipping radius was deduced according to the surface wetting characteristics and surface inclination angle

which were consistent with the experiment results.