Matching and optimization for a thermoelectric generator applied in an extended-range electric vehicle for waste heat recovery

In a conventional fuel vehicle, it is always difficult to find design points for a thermoelectric generator (TEG) because of the variation in engine power seen in different driving cycles. In contrast, the engine of an extended-range electric vehicle (EEV) is decoupled from the road load and only works at a single operating point in most cases, making it particularly suited for a TEG optimization design. This paper describes a method to match an optimized TEG to an EEV based on two criteria: TEG protection and high net power density. The trade-offs for TEG performance from TEG weight, added electric pump power consumption and backpressure are all taken into consideration. On this basis, the electric load resistance and configuration of the TEG are optimized, achieving a 11.6% increase of net power density compared to a preliminary designed TEG. The fuel economy of the optimized TEG integrated in an EEV (EEV-TEG) is assessed against that of a conventional EEV. The comparison shows that a 1.7% reduction in equivalent fuel consumption is obtained by the EEV-TEG, which is higher than that of a TEG applied in conventional fuel vehicles. These results exhibit the crucial importance of the method of and for a TEG to EEVs.