An experimental study on the effects of frosting conditions on frost distribution and growth on finned tube heat exchangers

Recently, the authors have published a paper which provided the frost distribution and growth along the airflow direction of finned tube heat exchangers (FTHXs), and demonstrated that some frost was accumulated on the edge of windward fins at a given frosting condition. As a follow-up to the work reported in the previous paper, in the current paper, the effects of frosting conditions on frost distribution and growth characteristics of FTHXs with different fin pitches were experimentally investigated. The results showed that the protruded thickness of frost on the edge of windward fins and the ratio of the frost mass on the edge of windward fins to that on the entire FTHX were both increased with the increases in air temperature (T_a) and relative humidity (RH_a), but decreased with an increase in initial air face velocity (v_a). In addition, the effects of RH_a on the mass ratio were more significant than those of T_a and v_a. Furthermore, the averaged frost density on the edge of windward fins was increased with an increase in RH_a; and that on the surfaces of fins and tubes was increased with an increase in v_a, but decreased with an increase in RH_a.