Exergo-technological explicit methodology for gas-turbine system optimization of series hybrid electric vehicles

Significant research efforts have been invested in the automotive industry on hybrid electrified powertrains in order to reduce the dependence of passenger cars on oil. Electrification of powertrains resulted in a wide range of hybrid vehicle architectures. The fuel consumption of these powertrains strongly relies on the energy converter performance, as well as on the energy management strategy deployed on board. This paper investigates the potential of fuel consumption savings of a series hybrid electric vehicle using a gas turbine as an energy converter instead of the conventional internal-combustion engine. An exergo-technological explicit analysis is conducted to identify the best configuration of the gas-turbine system. An intercooled regenerative reheat cycle is prioritized, offering higher efficiency and higher power density than those of other investigated gas-turbine systems. A series hybrid electric vehicle model is developed and powertrain components are sized by considering the vehicle performance criteria. Energy consumption simulations are performed over the Worldwide Harmonized Light Vehicles Test Procedure driving cycle using dynamic programming as the global optimal energy management strategy. A sensitivity analysis is also carried out in order to evaluate the impact of the battery size on the fuel consumption, for self-sustaining and plug-in series hybrid electric vehicle configurations. The results show an improvement in the fuel consumption of 22-25% with the gas turbine as the auxiliary power unit in comparison with that of the internal-combustion engine. Consequently, the studied auxiliary power unit for the gas turbine presents a potential for implementation on series hybrid electric vehicles.