Comparative thermo-structural analysis of annular cascade thermoelectric generator configurations for enhanced thermal reliability

A mult-stage module is used to improve the temperature distribution in annular thermoelectric generators (ATEGs) in round-shaped applications. This study investigates the performance of unileg cascade ATEGs and compares it with that of unicouple cascade ATEGs for the first time. The thermoelectric (TE) power and thermal stress of two- and three-stage configurations are analyzed using three-dimensional finite-element simulations. In a two-stage model, Half-Heusler and skutterudite are used as thermoelectric materials at the top and bottom stages, respectively. In a three-stage system, bismuth telluride is inserted at the bottom stage, below the Half-Heusler and skutterudite stages. The results reveal that the two-stage unicouple and unileg cascade ATEGs generate TE powers of 0.25 W and 0.29 W, respectively. In comparison, the three-stage unicouple and unileg systems produce 0.41 W and 0.46 W. The unileg multi-stage model outperforms unicouple cascade models by selecting strongly performing thermoelectric legs. Moreover, thermal stresses are reduced in the unileg models compared with the unicouple system because the thermal expansion coefficient mismatch between dissimilar annular TE legs is eliminated.