The effect of frosting on heat transfer to the evaporator and its consequent effect on heat pump performance have been investigated both experimentally and theoretically. The evaporator was of the plate fin type using R22 as a working refrigerant. The results of the model are in reasonable agreement with the experimental data.

KEYWORDS: heat pumps, heat flow, evaporators, heat exchangers, frost, finned tube heat exchangers, calculating, experiment, refrigerants, performance, R22.