Enhance the Heating Performance of an Electric Vehicle AC/HP System under Low Temperature

In order to improve the EV (Electric Vehicle) energy efficiency and explore the heating performances of the automotive heat pump under low ambient temperatures, an integrated AC/HP (Air Conditioning/Heat Pump) system was established and applied in a compact EV. Environmental chamber was employed to produce the target ambient conditions and scroll compressor was used to raise the operating speed. Refrigerant R134a and then R407C were tentatively served as the working fluids. In the ambient temperature range of -15∼0°C, the system near on-field heating behaviors were experimentally studied by varying the ambient temperature, the compressor speed and displacement. Variations of the EV cabin temperature and the compressor power consumption were measured to evaluate the system heating performances. Test results indicated that, although the heating performances were strongly affected by the operating conditions, the AC/HP system could provide the required heat for the EV cabin. It reduced the EV energy consumption distinctly compared to the original PTC heater. Test results also showed that the system performance still had the potential for further enhancement.