In the study

a heat pump system with three heat exchangers was applied on an air-conditioning system of an electric vehicle

in which R134a is the refrigerant. The bench of the heat pump system was constructed

and performance were tested in five conditions with respect to cooling and heating

and the effects of compressor speed

air volume

and ambient conditions on the system performance were examined. The tested performances under various operation conditions were used to analyze the feasibility of the system for electric vehicles. The experimental results indicate that when compressor speed corresponds to 3000 r/min at ﹣20 ℃

(1) the coefficient of performance (COP) of the system is approximately 1.5; (2) with the increases in the compressor speed

the COP initially increases and subsequently decreases; (3) the COP of the system increases with increases in the amount of air of the heat exchanger. Thus

the results reveal that the heat pump system saves electricity and improves the cruising range of vehicle mileage.