Empirical Study on the Efficiency of an LPG-Supplied Range Extender for Electric Vehicles

A range extender is an auxiliary power unit, usually consisting of an internal combustion engine and an electric generator, which is used to charge a battery of an electric vehicle in order to increase its range. This paper considers a range extender supplied with liquefied petroleum gas (LPG). The aim is to provide detailed data on thermal efficiency, brake specific fuel consumption (BSFC), and unit emission of carbon dioxide (CO2) in a broad spectrum of range extender operating conditions defined by rotational speed and torque. The experimental investigation has been conducted using a laboratory test stand equipped with an energy dissipation system of adjustable resistance. Measurement results, including fuel flow rate, were processed using custom algorithm for generating maps, i.e., two-dimensional dependencies of the considered parameters on the rotational speed and torque. The maps obtained for LPG supply were compared with those for gasoline supply. The results demonstrated feasibility of LPG-supplied range extender. Its BSFC and thermal efficiency were at a comparable level to those obtained for gasoline supply, but with less CO2 emission. The empirical data collected has been adopted in the simulation of extended-range electric vehicle in a driving cycle, showing the potential of utilizing the results of this study.