Droplets condensation and growth in the early stage of frosting on hydrophobic surfaces was researched under the natural convection condition. A heat transfer and growth model considered noncondensable gas was developed to clear the influences of surface contact angle and surface temperature on droplets growth. The results show that the two main thermal resistances during the droplet growth stage are the conduction thermal resistance inside the droplet and the phase interface thermal resistance

and both the two thermal resistances increase with surface contact angle

so droplets have a lower growth rate on surface with big contact angle. In addition

the droplets grow faster on surfaces with lower temperature

because colder surfaces could cause bigger heat transfer temperature differences.