A Simulation Study of the Optimal Integration of a Rankine Cycle Based Waste Heat Recovery System into the Cooling System of a Long-Haul Heavy Duty Truck 2018-01-1779
ABSTRACTAs a promising solution to improve fuel efficiency of a long-haul heavy duty truck with diesel en-gine, organic Rankine cycle (ORC) based waste heat recovery system (WHR) by utilizing the ex-haust gas from internal combustion engine has continuously drawn attention from automobile industry in recent years. The most attractive concept of ORC-based WHR-System is the conversion of the energy of exhaust gas recirculation (EGR) and exhaust gas from Tailpipe (EGT) to mechanical energy which is refed to the engine crankshaft. Due to the shift of the operating point of the engine by applying WHR-System, the efficiency of the global system will be increased and the fuel consumption can be reduced. However, the integration is challenging by using the cooling system of the Truck as the heat sink of the Rankine Cycle. The coolant temperature at the inlet of condenser and the potential of the cooling system have a strong influence on the efficiency of Rankine cycle as well as the integrated system of engine with the WHR-system. This paper aims to investigate the impacts of different configurations for the integration of WHR-System into the Truck cooling circuit on the overall efficiency. A complex 0D/1D-simulation model for a turbocharged production heavy duty engine with low-/ high-temperature cooling circuit and a WHR system with ethanol as working fluid have been established in GT-Suite. An optimal integration concept has been evaluated by simulation with coupled models in consideration of cooling fan engagement, thermostat operation and interactions between subsystems. Results show that an average fuel consumption reduction of 4.8% has been accomplished under steady-state conditions as well as during transient cycles while the NOx emission satisfies the increasingly stringent emission legislation.
Kangyi Yang, Michael Grill, Michael Bargende
FKFS, Universitat Stuttgart
International Powertrains, Fuels & Lubricants Meeting