Performance investigation and optimization of an L-type thermoelectric generator

Structural optimization is one of the effective means to improve thermoelectric generator (TEG) performance. Considering the inconsistent material parameters between P-type and N-type thermoelectrics, this paper proposes an L-type TEG configuration, where P-type and N-type semiconductors are designed with different heights and connected by L-shaped conductive strips. In addition, a thermal-electric-mechanical numerical model is established to evaluate and optimize the thermoelectric and mechanical performance of the L-type TEG. Results show that when the temperature difference is 400 K and the height ratio of the P-type to N-type semiconductor is 0.385, the L-type TEG achieves a maximum output power of 1.96 W and a maximum efficiency of 7.8 %. This is 2.39 % and 1.44 % higher, respectively, than the traditional It-type TEG. Although the temperature difference is not related to the optimal configuration of the L-type TEG, it will affect the extent of performance improvement, and the smaller the temperature difference, the greater the percentage gains of the L-type TEG compared to traditional design. In addition, the greater the difference in parameters (including Seebeck coefficient, thermal and electrical conductivity) between P-type and N-type is, the more significant the improvement of the L-type design will be. Specifically, the difference in electrical conductivity contributes to the increase of the output power, while the increase in the efficiency is affected by both the electrical conductivity and the thermal conductivity. This study provides a new perspective on the structural optimization of TEGs.