Thermoelectric generator optimization for hybrid electric vehicles

Abstract

Significant research efforts are considered in the automotive industry on the use of low carbon alternative fuels in order to reduce carbon emissions of future vehicles, some of which are only compatible with external combustion machines. These machines are only suitable for electrified powertrains relying on electric propulsion, particularly in range extenders, where the energy converter operates steadily at a constant power at its optimal efficiency. The fuel consumption of these powertrains strongly relies on the performance of the energy converter in terms of efficiency. This paper presents the first study in literature that investigates the potential of fuel savings of an extended range hybrid electric vehicle using a thermoelectric generator system as energy converter substitute to the conventional internal combustion engine. An exergo-technological explicit analysis is conducted to identify the different thermodynamic configurations. An extended range vehicle model is considered and the different configurations are integrated as auxiliary power unit. Fuel consumption simulations are performed on the worldwide-harmonized light vehicles test cycle. Results are compared to the reference internal combustion engine operating as auxiliary power unit. The recuperative reheat two-stage thermoelectric generator is selected among numerous identified thermodynamic configurations, offering high efficiency and net specific work, and consequently lower fuel consumption compared to other configurations. This innovative thermodynamic configuration identified through the methodology proposed in this paper has been patented. Also, this study highlights the importance of increasing the thermoelectric generator’s module merit factor in order to achieve system efficiency comparable to the internal combustion engine, which makes this energy converter a potential for the implementation in future powertrains with zero carbon alternative fuels.