Micro gas turbine small-scale effects in range extended electric vehicles

Application of a range extender in an electric vehicle can reduce the battery bank size and extend the driving range on a need basis. A micro gas turbine offers high power density, fuel flexibility, a reliable thermal efficiency (with recuperation), and less raw exhaust gaseous emissions compared to an internal combustion engine. However, micro gas turbines also incur low component performances due to small-scale effects related to high viscous losses, heat transfer between hot and cold sections, and manufacturing and assembly constraints compared to their larger counterparts. In this paper, the micro gas turbine thermodynamic cycle has been designed in Gas Turbine Simulation Program (GSP) and evaluated in terms of the small-scale effects simultaneously with the battery bank energy and charging time analysis. The key objective is to demonstrate the effectiveness of a micro gas turbine in saving the weight of a range-extended electric vehicle while understanding the impact of small-scale effects on the battery bank energy and charging time. Results indicate that a relatively smaller 22-kWh battery bank can be utilized with prospects of cost-savings together with a 47-kW micro gas turbine range extender to achieve an average driving range of 100 km and a charging time of 30 min for the baseline electric vehicle. Furthermore, the compressor and turbine isentropic efficiencies are found to have a significant impact on the overall battery bank performance.