Analysis on optimal length scale of thermoelectric generators when using different circuit layouts

Abstract

Using thermoelectric generators (TEGs) to recover waste heat is a potential technological approach. To achieve maximum thermoelectric conversion power, scale optimization of thermoelectric modules has been reported in previous studies. However, the results obtained were all based on numerical calculations, and the analytical solution could not be proven theoretically. Therefore, understanding of the internal mechanism of the structural optimization theory is limited. In addition, the relevant optimization results were based on a full-series circuit, and no structural optimization theory for other circuit types has been proposed. To fill this gap, this study adopts a method that combines theoretical derivation and numerical calculation. First, the analytical solution of the optimal scale is derived by taking the full series as an example, and the existence of an optimal structure of the thermoelectric modules is theoretically confirmed. Subsequently, the scale optimization performance of the thermoelectric structure based on different circuit structures was further analyzed, providing theoretical guidance for the optimization of the thermoelectric structure under different circuit connection modes. The results indicate that the optimal lengths for different circuit layouts are quite different, regardless of whether maximum total power or net power is used as the optimization objective. However, for convenience, the optimal length of the full-series circuit mode can be used to design a constant length for all types of multi-stage series circuit modes when the objective is to maximize the net power output. Using this method, the percentage deviation of the obtained power from its theoretical peak net power can be less than 0.6% for the example presented in this study.