Experimental Study of Frost Growth Characteristics on Surface of Fin-tube Heat Exchanger

Abstract

The dynamic frost growth characteristics such as the frost thickness, frost mass on the surface of the fin-tube heat exchangers and the refrigeration capacity were experimentally investigated on different conditions of air temperature, relative humidity, and face velocity in the psychrometric rooms. The ethylene glycol–deionized water mixture (50% by volume) was used as refrigerant and a precise low temperature thermostat bath was used as cold source. The experimental results indicate that all of the frost thickness, air pressure drop, and refrigeration capacity decrease with the decrease in the air temperature and relative humidity, but the total frost mass increases with the decrease in the air temperature and relative humidity, which means that the lower the air temperature and the relative humidity, the bigger the density of the frost layer. The face velocity has little effect on the frost thickness, and the lower of the face velocity is, the faster the refrigeration capacity of the fin-tube heat exchanger drops. Therefore the larger face velocity can be used in actual application of air source heat pump to weaken the drop of refrigeration capacity caused by frosting.