Realizing ultrahigh ZT value and efficiency of the Bi₂Te₃ thermoelectric module by periodic heating

Thermoelectric power generation is regarded as a promising technology to convert waste heat into electricity. This study aims to address the low conversion efficiency of thermoelectric modules and introduces a novel periodic heating method to enhance their performance. Two new indicators, time average ZT_ta value and effective conversion efficiency, are introduced to assess the dynamic behavior of thermoelectric modules. A Bi₂Te₃-based thermoelectric module with n-type Bi₂Te_3-xSe_x and p-type Bi_xSb_2-xTe₃ materials is adopted as the research objective and tested on a designed transient experimental setup. Besides, a transient numerical model is developed to explore the optimal transient heat source and study the effect of various parameters on dynamic behavior. Compared with the steady-state efficiency of 3.76% and ZT_ta value of 0.78 at a heat supply of 60 W, the time average efficiency and ZT_ta value are improved by 52.93% and 43.59% respectively using the periodic heating method. Also, a smaller leg height, a larger leg area, more TE couples, and lower thermal conductivity are suggested for improving the dynamic behavior. This work offers a new periodic heating method to improve the output performance of thermoelectric modules, which may promote the broader application of thermoelectric power generation technology.