An electric vehicle is an environment-friendly automobile which emits no tailpipe pollutant. The conventional vehicle adopting an internal combustion engine inside the vehicle is heated up by using waste heat generated from the engine. However, for the electric vehicle, an alternative solution for the heating is required with the absence of engine. Recently, a heat pump system, which is widely used for residential heating due to higher efficiency, has been studied for its adoption in the electric vehicle as a heating system. In this study, a heat pump system utilizing air source and waste heat source from electric devices was investigated experimentally. The performance of the heat pump system was investigated varying the outdoor temperature and recovery heat amount. The experimental results show that there exists an optimal combination of dual sources in the design of flow distribution at dual heat sources.
The most important component for utilizing waste heat source is the plate heat exchanger. A plate heat exchanger is a type of heat exchanger that uses metal plates to transfer heat between two fluids. This has a major advantage over a conventional heat exchanger in that the fluids are exposed to a much larger surface area because the fluids spread out over the plates. In this study, the evaporation heat transfer characteristics of a brazed plate heat exchanger was investigated experimentally using antifreeze coolant (ethylene-glycol water) and R134a as the two fluids in a heat exchanger. The effects of refrigerant mass flux were measured by changing coolant temperature, mass flow rate, and composition. R134a evaporation heat transfer coefficient of the heat exchanger was calculated using the logarithmic mean temperature difference (LMTD) and Wilson plot method. Experimental results showed that the average vaporization heat transfer coefficient increased as the refrigerant mass flux increase. The experimental heat transfer coefficients were also compared with the pre-studied correlations for evaporation heat transfer coefficients.