Local variation of frost layer thickness and morphology

Frosting is an important phenomenon encountered in the cryogenic industries in connection with gas coolers, refrigerators, heat pumps, etc. It may adversely affect the performances of those devices. This paper experimentally studied the local frost formation process on a cold surface with natural airflows or forced airflows over it. The frost layer thickness was found to increase stepwise during the frost formation process. This increase pattern was ever indicated only by one literature. The literature attributed the pattern to the melting of frost crystals at the frost surface. However, present observation of the morphology of the frost layer surface suggested that the growth of water drops or ice particles at the initial period caused the first slowly increasing of the frost layer thickness; the following growth of acerose-shaped ice crystals caused the rapidly increasing of the frost layer thickness; thereafter, the column-shaped ice crystals on the surface grew in its length and radius alternatively, which caused the frost layer thickness increasing rapidly and slowly alternatively.