연료전지 스택 배열을 활용한 CO₂ 난방 시스템 배열열교환기 성능 특성에 관한 실험적 연구

The aim of this study is to investigate the performance characteristics of CO₂ Heat Pump(H/P) system using the stack cooling coolant / refrigerant heat exchanger for fuel cell electric vehicles(FCEV). The present heating system for FCEV uses PTC heater, which results in lower fuel efficiency and reduction of driving range. To cope with heating performance improvement without additional power consumption, one of possible methods is to use stack coolant heat for FCEV. Due to high pressure and temperature operating condition for CO₂, CO₂ heat pump has been concerned that it seems to cover heating capacity with the similar capacity of engine coolant heating system. Furthermore, CO₂ heating system is free of environmental regulations for a vehicle refrigerant. In this study, experiments to analyze heating performance characteristics using the coolant / refrigerant heat exchanger have been done with various operating conditions, which are likely to match the actual vehicle’s driving conditions under cold ambient conditions, such as variation of coolant flow rate and interior air temperature. Experimental results show that the heating capacity has Max. 9.5 ㎾ @ coolant temperature 60℃, interior air outlet temperature is up to 45℃ @ ambient temperature -20℃, and the capacity of the coolant / refrigerant heat exchanger is 6.5 ㎾ @ coolant temperature 60℃. From various experimental results, optimal coolant flow rate to have optimum heating performance seems to exist under a certain ambient temperature(5.0 LPM@ ambient temperature -20℃)