Output and mechanical performance of thermoelectric generator under transient heat loads

Geometry optimization and pulsed inputs have been introduced as some of the effective methods to enhance the performance of thermoelectric devices. In this work, the geometric structure of a Bi2Te3-based thermoelectric module is optimized systematically using two-step integrated optimization method in steady state, and then the effect of transient heat flux on the output and mechanical performance is investigated deeply. The simulative results show that the optimization directions for mechanical and output performance are usually opposite. The optimal Ap/An, H/Anp and N of the Bi2Te3-based module are 1.6, 1.5 and 8, respectively. Moreover, the thicker He and thinner Hcs favor the improvement of output performance, however, considering the mechanical property, the optimal He and Hcs are regarded as 0.3 mm. In addition, using pulsed heat flux can improve the output performance and obtain a smaller average stress in a long period. The suitable duty cycle, smaller amplitude ratio and rectangular heat flux are beneficial for power enhancement and stress optimization. However, pulsed input brings frequent and repeated temperature changes, which is a challenge to the lifespan of thermoelectric modules. These simulated results will benefit the enhancement of output and mechanical performance of thermoelectric devices in the practical operation process.