Experiment Study on Defrost of Precooling Heat Exchanger With Tube Bundle

In this paper, the frost and defrost characteristics of pre-cooling heat exchanger with fine tube bundle was investigated experimentally for the inlet coolant temperature range of -10~-60℃. The frost and defrost process of the single-row tube arrangement is researched by image comparison and pressure drop measurement. The method of injecting ethanol to the main flow is employed to remove frost. The results indicate that, the frost layer thickness increases with the coolant temperature decreasing, but the increasing tendency slowing down at constant air humidity. The frost layer thickness decreases with the air humidity increasing at constant coolant temperature. The result verified that, at a coolant temperature above -60℃, injecting ethanol can effectively inhibit the formation of the frost layer within eight minutes.