AN EMPIRICAL STUDY OF FROST ACCUMULATION EFFECTS ON LOUVERED-FIN, MICROCHANNEL HEAT EXCHANGERS

摘要

The use of folded-louvered-fin, microchannel heat exchangers in refrigeration and heat pump applications, where normal operating conditions give rise to frost accumulation on the airside heat transfer surface, is experimentally studied. Heat transfer and pressure drop data are presented for heat exchangers with different fin geometries. The visualization of frost growth via a 0.5mm fiberscope indicates that the bridging of louver gap by frost contributes to a decrease in airside heat transfer coefficient as the frosting process evolves. The bridging of the louver gap implies that the airside flow pattern changes from a louver-directed to a duct-directed flow, with a deleterious impact on heat transfer. The impacts of frost growth on heat transfer and thermal-hydraulic performance for different fin geometries are compared in terms of f and j factors.