Analysis of the effect of a pulsed heat flux on the performance improvements of a thermoelectric generator

Abstract

In this work a transient simulation including Joule heating and Peltier effect using Comsol 5.3, is carried out to assess the thermoelectric performance of a bismuth telluride based thermoelectric generator (TEG) under periodic heating and steady state heating. The transient model was experimentally validated in the case of a constant heat source. A periodic pulsed heat source generates a periodic temperature difference ΔT across the TEG legs. While the time average of ΔT is identical to the temperature difference under a constant heat source with equivalent heat flux input, the time average of (ΔT)2 is larger, resulting in improved output power. Under pulsed heat flux, the maximum enhancement of the output power under periodic heating to the output power under steady state heating (PPH/PSS) is achieved for a time period of 1000 s and a duty cycle 10%. Moreover, it can be seen that PPH/PSS enhancement is independent of the input heat flux under a given value of a time averaged heat flux 〈q〉. It is found that geometric dimensions of thermo-elements (TE) enhance significantly the thermoelectric performance of the device. However, it is observed that for a given value of leg length (L), the output power becomes independent of L. Hence, this result can facilitate the prediction of TEG performance.