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

• Thermal and electrical contact resistances of 3.65 × 10−5 m2⋅K⋅W−1 and 1.18 × 10−10 Ω⋅m2⋅K are obtained. • Time average ZT value and effective efficiency are greatly improved by periodic heating. • Efficiency of 5.75% and ZT value of 1.12 are achieved under the optimal transient heat source. • Smaller leg height, larger leg area, more TE couples, and lower thermal conductivity are suggested. 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 Bi 2 Te 3 -based thermoelectric module with n-type Bi 2 Te 3-x Se x and p-type Bi x Sb 2-x Te 3 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. [ABSTRACT FROM AUTHOR]