In a companion experimental investigation (ASHRAE RP-622), it was observed that the evaporation and sublimation heat rates were significantly larger than the melting heat rate during hot-gas defrosting. Part of the rationale for conducting the present investigation was to validate the above observation. Thus, the purpose of this paper is to describe a mathematical model for predicting the evaporation, sublimation, and melting heat rates on a frosted cylindrical cooler during hot-gas defrosting. The frosted cylindrical cooler represents a single nonfinned tube in the first row of a typical coil employed in industrial refrigeration applications. This model should provide some insight into the hot-gas defrosting processes typically found in the operation of true-to-life industrial freezers.

Units: I-P