Predictions of segmented thermoelectric unicouples performance at hot temperatures ≤873 K and cold temperature of 298 K

The performance of segmented thermoelectric unicouples (STUs) for terrestrial energy conversion applications is optimized both for maximizing efficiency and electrical power density. The STUs operate at cold side temperature of 298 K and hot side temperatures of 873 K, 773 K and 673 K. The composition, number, and length of the segments in the n- and p-legs change with the hot side temperature. However, the number of segments in the STUs optimized for maximum power density is generally fewer than in those optimized for maximum efficiency. For a hot side temperature of 873 K, assuming zero contact resistance, the optimized STU for maximum efficiency operates at a peak efficiency of 15% and peak electrical power of 0.34 W_e, versus only 13% and 0.48 W_e, respectively, when optimized for maximum electric power density. When the contact resistance per leg increases to 150-μΩ-cm², the peak efficiencies decrease to 13.3% and 10.9%, respectively.