Geometry optimization of two-stage thermoelectric generators using simplified conjugate-gradient method

•Integrating computer-aided analysis with an optimization method to design and optimize TEGs.•Obtaining multi-objective and multi-parameter optimization of structure for a two-stage TEG module.•Properly balancing the power output and conversion efficiency to improve them simultaneously.

Thermoelectric devices can convert thermal energy directly into electrical energy. The aim of this study was to develop an approach for integrating computer-aided analysis with an optimization method that could be applied to the design and optimization of thermoelectric generators. The optimization framework consisted of a model generator, a direct solver, and a numerical optimizer. The simplified conjugate-gradient method (SCGM) was used to build the optimizer, and the general-purpose finite-element code was used for the direct solver and model generator. This approach was applied to the multi-objective and multi-parameter optimization of geometric thermoelectric generators to design an optimal structure for both a two-stage bismuth-telluride (BiTe)-based and skutterudite-based thermoelectric generator (TEG) module. The leg length and the ratio between the cross-sectional areas (i.e., footprint) of the semiconductor columns and the TEG module were found to significantly affect the TEG performance; hence, all were incorporated into the present optimization study. Multi-objective optimization was used to realize a design that properly balanced the power output and conversion efficiency so that both improved simultaneously.