하이브리드 자동차의 효율적 배기열회수시스템 개발을 통한 연비 개선

Since the propulsion systems of vehicle have changed from a single energy source based on conventional internal combustion engine to hybrid system including more electrical system such as full type of hybrid electric vehicle or plug-in hybrid electric vehicles, a new transition associated with vehicle thermal management arises. The success of improved fuel economy is the proper integration of thermal management components which are appropriately performed to reduce friction and wasted energy. The thermal management systems of vehicle are able to balance the multiple needs such as heating, cooling, or appropriate operation within specified temperature ranges of propulsion systems. More efficient thermal management systems are required to improve the fuel economy in the hybrid electric vehicles because of the driving of electric traction motor and the increase of engine off time. The decrease of engine operation time may not sustain the proper temperature ranges of engine and gearbox. As an engine starts at low ambient temperature, heat from the wasted heat of exhausted gas can be supplied to engine and gearbox at initial warm-up. This research describes the one of cost effective thermal management solutions recovering exhaust gas heat exchanging system with coolant and gear box oil simultaneously. It is more advantageous to increase the temperature of the engine oil or gear box oil rather than to increase the coolant temperature. Consequently, the experimental result of this system improved 2.5% of fuel economy at UDDS drive cycles. The main benefit using exhaust gas heat recovery system is fuel economy improvement. However, to practically apply recent thermal management technologies in commercial use, not only improved performance for the low energy density but also cost in a viable vehicle package are necessary in general. Developed exhaust gas heat recovery system of integrated heat exchanger type is 6 times more competitive than coolant only type’s and more effective solution than Rankine cycle type’s in passenger vehicle.