Experimental study of frost formation on a fin-and-tube heat exchanger by natural convection

•Frost formation is studied on a fin-and-tube heat exchanger by free convection.•Frost formation is observed only on the tip of the fins.•Heat transfer and frost growth rate initially increases but then decreases.•Frost deposition is a strong function of ambient temperature and relative humidity.•Correlations are developed for frost growth and heat transfer rate.

This paper presents an experimental study of frost growth on a fin-and-tube heat exchanger by natural convection. Experiments are carried out for refrigerant mean temperature of −10 °C, −15 °C and −20 °C, ambient temperatures between 20 °C and 30 °C and relative humidity varied from 50% to 70%. The results include changes of frost thickness and its impact on heat transfer rate under different environmental condition. Frost growth depends on time and location along the fin and tube heat exchanger. Frost thickness varies due to changes of air velocity, temperature and concentration boundary layers. The heat transfer rate and frost growth show strong dependence on refrigerant mean temperature, ambient air temperature and relative humidity. According to the measurements, some practical empirical correlations of frost growth and heat transfer are presented in terms of relevant dimensionless parameters.