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• A microchannel heat exchanger with plain-louvered fins is proposed. • Frosting characteristics on plain- and corrugated-louvered fins are compared. • The heat exchanger with plain-louvered fins shows 16.7% higher performance. • Miles per gallon of electric vehicle with plain-louvered fins increases by 25.2%. 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. [ABSTRACT FROM AUTHOR]

An analytical study is conducted to optimize the injection-port geometries of a vapor injection asymmetric scroll compressor operating under various climatic conditions. A numerical model was developed to predict the performance of the vapor injection asymmetric scroll compressor in the heating mode according to various operating parameters, and this numerical model was validated using data measured in a vapor injection heat pump. The effects of the location and number of injection ports on the performance of the asymmetric scroll compressor were analyzed using the numerical model. Both the optimal injection-port angle and required injection-port area increased as the outdoor temperature decreased in order to increase the injection mass flow rate. The optimized injection port designs were then proposed for the asymmetric scroll compressor in order to achieve the maximum SCOP (seasonal coefficient of performance) under various climatic conditions, improving the SCOP by 2%–6% relative to the baseline injection compressor. [ABSTRACT FROM AUTHOR]