Performance improvement of heat pumps using novel microchannel heat exchangers with plain-louver fins during periodic frosting and defrosting cycles in electric vehicles

Air source heat pumps have been proposed as effective climate control systems in electric vehicles. However, during cabin heating, air can condense on the cold surface of an outdoor heat exchanger in the air source heat pump. Frost can accumulate on the outdoor heat exchanger when the surface temperature drops below the freezing point. In this study, a novel microchannel heat exchanger with plain-louvered fins was developed as an outdoor heat exchanger to improve the frosting and defrosting characteristics of the air source heat pump in electric vehicles. Comparative performance evaluations of microchannel heat exchangers with the plain- and conventional corrugated-louvered fins were conducted during periodic frosting and defrosting cycles. The frosting period and peak heating capacity of the air source heat pump with the plain-louver fin heat exchanger were 102.7% and 14.0% higher than those with the corrugated-louvered fin heat exchanger, respectively. Miles per gallon equivalent of electric vehicle with the plain-louvered fins was 25.2% higher than that with electric heating. Overall, the microchannel heat exchanger with the plain-louvered fin is recommended as a preferred outdoor heat exchanger in the air source heat pump for electric vehicles.