The influence of Thomson effect in the performance optimization of a two stage thermoelectric generator

In this paper, the exoreversible and irreversible thermodynamic models of a TTEG (two stage thermoelectric Generator) considering Thomson effect combined with Peltier, Joule and Fourier heat conduction have been investigated using exergy analysis. The expressions for interstage temperature, optimum current for the maximum power output condition and energy/exergy efficiency of a TTEG are derived. The number of thermocouples in the first and second stages of a TTEG for the maximum power output and energy/exergy efficiency conditions are optimized as well. The results show that the exergy efficiency of TTEG is greater than the energy efficiency. In an irreversible TTEG with 30 thermocouples, and with heat source temperature (TH) of 450 K and heat sink temperature (TC) of 300 K, the obtained maximum power output, maximum energy and exergy efficiency are 0.2996 W, 4.35% and 13.05% respectively. It has also been proved that the optimum number of thermocouples obtained in the first and second stages of a TTEG are different from the previous studies because of the influence of Thomson effect. This study will help in the designing of the actual multistage thermoelectric generator systems.