폐열원 이용방식에 따른 자동차용 난방시스템의 성능평가에 관한 실험적 연구

Abstract

In this study, a heat pump system is developed which using waste heat from fuel cell driven vehicle. The heat pump system can be operates three types of driving mode. First configuration is that the system can be use the air source heat as conventional heat pump system. Second configuration is the system uses waste heat from fuel cell stack through with plate heat exchanger. The last configuration is the stack heat supplied to the preheater which is located in upstream flow of air source heat exchanger. In accordance with each operation mode, the experimental study was conducted to achieve a heating performance of the system. In this study, refrigerant charge test was conducted in prior to the main experiments and found out that the optimum charge can be achieved at 800g with 50% opening of full scale of the EEV. In the conventional heat pump operation of the heating system, the experiment was carried out with respect to the compressor rotation speed driving characteristics. If the rotational speed of the compressor increased, the power consumption is also increased. However the results shows that the system have a higher COPh at lower EEV openings of the expansion valve and even the openings of the expansion valve is increased the system could not get more capacity due to the limitation of the outdoor heat exchangers capacity. In the second air pre-heater unit mode, the system can get the highest COPh at 1,200rpm compressor rotation speed, 50℃ heat stack temperature, and 50% EEV openings. At this configuration, the air temperature, which is sucked into the evaporator, was warm up by the waste heat from fuel cell stack, the system performance is increased about 42.5% compare to the conventional heat pump system. When the system uses the waste heat from the stack directly to the evaporator through the plate heat exchanger, the system COPh is increased about 68% compare to the air pre-heater unit mode. The system shows highest COPh at this configuration at 1,200rpm compressor speed, 50℃ stack waste heat temperature, and 75% EEV openings. The system performance increased with the compressor speed and has a small effect on the outside air temperature in the three configuration, and it shows that the highest COPh when the system uses the waste heat directly to the evaporator through the plate heat exchanger.