Characterization of thermoelectric conversion for a stacked leg with parasitic heat radiation

The study presents a detailed analysis of thermoelectric conversion for power generation, and demonstrates the effects of contact electrical and thermal resistance as well as heat radiation. A thermoelectric leg is stacked with two segments of n-type half-Heusler material on a testing bench, and characterized for power generation under four large temperature differences across the leg. The voltage, heat flow, electric power and thermoelectric efficiency are measured at various currents. In comparison they are calculated numerically with finite element simulation by disregarding parasitic effects. When the leg is subjected to 500 °C at its hot side, the maximum efficiency of 7.5% is attained experimentally, in contrast to 10.5% from the calculation. The discrepancy of internal resistance between the experiment and calculation is ascribed to the inaccuracy of bulk resistivity. The radiative heat flow without the leg on the bench is measured by the water-flow calorimeter, while it is simulated without or with the leg on the bench respectively. Thermal resistance analysis shows a 12–13% overestimation of thermal conductivity of the half-Heusler material. It provides an approach to quantifying the contact resistances and heat radiation as well as to checking the material thermoelectric properties