Effects of Frost Formation on the Performance of a Vertical Plate Heat Exchanger

In the study, the following factors are investigated experimentally for a vertical parallel plate heat exchanger under the frosting condition;the growth of frost layer, the characteristics of heat and mass transfer, the change of mass flow rate of air passing through the heat exchanger, and the pressure drop in the heat exchanger. The amount of heat and mass flux of water vapor transferred from the air stream to the heat exchanger surface is large at the early stage of frosting and then decreases dramatically, and the extent of decreasing rate becomes moderate with time, the frost layer formed near the inlet of the heat exchanger is thicker and denser than that formed near the outlet. It is found that the gradient of the amount of frost along the flow direction increases with time. With increasing inlet air temperature, the frost thickness becomes thin and a frost with high density is formed. Frost thickness and density increases with increasing inlet air velocity. Energy transfer resistance between the air and cooling plate increases with increasing air humidity and decreases with the increase of air temperature, cooling plate temperature, and air velocity.