Thermal–electrical–structural performances of hot heat exchanger with different internal fins of thermoelectric generator for low power generation application

In this study, an electro-thermo-structural coupled numerical analysis is conducted to evaluate the thermal, electrical, and structural performances of a thermoelectric generator system. The hot heat exchangers with six different internal fin structures are compared in terms of temperature distribution, pressure drop, net power output, overall efficiency, and stress using the coupled numerical approach. Experiments are conducted on the heat exchanger with straight fins to validate the accuracy and reliability of the proposed coupled analysis. The hot gas outlet temperature, coolant outlet temperature, power output, and stress predicted using the coupled approach are validated within errors of 1.5, 6, 3, and 5.45%, respectively. Among the proposed heat exchanger designs, the heat exchanger with inclined fins and that with the combination of inclined and perpendicular fins exhibit higher net power outputs and overall efficiencies. The heat exchanger with the inclined fins and that with the combined fins exhibit overall efficiencies of 1.81 and 1.88% and net power outputs higher by 29 and 35%, respectively, than those of the heat exchanger with straight fins at the hot gas temperature of 600 °C. At the hot gas temperature 600 °C, the maximum stresses induced in the heat exchanger with the inclined fins and that with the combined fins are approximately 25.87 and 26.53 MPa, respectively, which are lower than the maximum allowable stress of 70 MPa.