Comparison and parameter optimization of a segmented thermoelectric generator by using the high temperature exhaust of a diesel engine

Abstract

This paper proposes a segmented thermoelectric generator (TEG) that can be used to recover exhaust waste heat from a diesel engine (DE). A mathematic model of the segmented TEG was constructed based on the low-temperature thermoelectric material bismuth telluride and the medium-temperature thermoelectric material skutterudite. Performance was compared between segmented and traditional TEGs, and the performance of the segmented TEG was optimized based on the comparison. The model simulates the impact of relevant factors, including the exhaust temperature, cold source temperature, thermocouple length, and the length ratio between the two materials, on the output power and conversion efficiency. The results showed that the segmented TEG is more suitable than the traditional TEG for a high-temperature heat source and for large temperature differences. Moreover, the maximum output power was inversely proportional to the thermocouple length; however, the maximum conversion efficiency was directly proportional. The ratio of the two materials depended on the temperature of the heat and cold source. Finally, a comparison of application potential of the TEGs showed that the segmented TEG had greater potential for waste heat recovery compared with the traditional TEG.