Performance comparison and optimization of thermoelectric generator systems with/without stepped-configuration

In view of the poor performance of traditional thermoelectric generator(TTEG), this paper presents a stepped-configuration thermoelectric generator(STEG) integrating thermoelectric modules(TEM) through direct or indirect contact with the hot medium. TEG is divided into a series of control bodies along the gas flow direction based on the finite volume method, the differential equation of the transient energy conservation equation is established in the control body according to the energy conservation, and the model is verified. The thermoelectric characteristics of TTEG and STEG are compared with the structure parameters of the TEM, the input temperature and flow rate of the hot medium(T_in and m_in) and the input temperature and flow rate of the cold medium(T_water,in and m_water,in). The results show that conversion efficiency(η_TE) is the key factor to determine system efficiency(η_sys). The height(H_TE) corresponding to the maximum η_TE decreases gradually with T_in and m_in. The filling factor(FF) corresponding to the maximum η_TE and η_sys are 0.2–0.3 and 0.4–0.7. Compared with the original structure, heat exchanger efficiency(η_HE) of the optimized structure is slightly reduced, η_TE is obviously rised, and η_sys is enhanced. When T_in is 1173 K and m_in is 2 g/s, the maximum η_sys of TTEG and STEG are 2.70% and 3.34%, respectively. The current uniformity coefficient(β) drops with T_in, and the overall β is improved by 34.3%–44.4% after optimization. This paper proves the superior performance of STEG and provides insights for TEG progress.