Geometry Optimization for Miniaturized Thermoelectric Generators.

Thermoelectric materials capable of converting heat into electrical energy are used in sustainable electric generators, whose efficiency has been normally increased with incorporation of new materials with high figure of merit (ZT) values. Because the performance of these thermoelectric generators (TEGs) also depends on device geometry, in this study we employ the finite element method to determine optimized geometries for highly efficient miniaturized TEGs. We investigated devices with similar fill factors but with different thermoelectric leg geometries (filled and hollow). Our results show that devices with legs of hollow geometry are more efficient than those with filled geometry for the same length and cross-sectional area of thermoelectric legs. This behavior was observed for thermoelectric leg lengths smaller than 0.1 mm, where the leg shape causes a significant difference in temperature distribution along the device. It was found that for reaching highly efficient miniaturized TEGs, one has to consider the leg geometry in addition to the thermal conductivity.