Fuel Consumption Saving Potential of Stirling Machine on Series Parallel Hybrid Electric Vehicle: Case of the Toyota Prius

Investigations on alternative fuels and new hybrid powertrain architectures have recently undergone significant efforts in the automotive industry, in attempt to reduce carbon emissions from passenger cars. The use of these fuels presents a potential for re-emerging the deployment of external combustion non-conventional engines in automotive applications, such as the Stirling engines, especially under the current development context of powertrain electrification. This paper investigates the potential of fuel consumption savings of a series-parallel hybrid electric vehicle (SPHEV) using a Stirling machine as fuel converter. An exergo-technological explicit analysis is conducted to identify the Stirling system configuration presenting the best compromise between high efficiency and automotive implementation constraints. The Stirling engine with combustion chamber preheater is prioritized. A SPHEV model is developed based on the Prius power-split hybrid electric architecture. Energy consumption simulations are performed on the worldwide-harmonized light vehicles test cycle (WLTC) using dynamic programing as global optimal energy management strategy. Results show improved fuel consumption performance of the Stirling machine compared to the ICE. In addition, the Stirling offers other intrinsic advantages such as low noise and vibration operation and mainly multi-fuel use capability. Consequently, the studied Stirling presents a potential for implementation on SPHEVs.