Structural optimization of thermoelectric modules for waste heat recovery from exhaust of solid oxide fuel cells

The solid oxide fuel cell is an efficient and clean energy conversion device which operating at high temperatures. Its exhaust temperature can reach as high as 600 °C–1000 °C, making waste heat recovery highly valuable. Thermoelectric generators can harness waste heat from exhaust gases to generate power, and refining the design of thermoelectric modules can improve the power generation performance. However, the results of structural optimization are influenced by thermal boundary conditions. This study establishes a multiphysics coupling model for thermoelectric modules and conducts structural optimization of the modules based on the heat transfer parameters of the exhaust gases from solid oxide fuel cell. The findings indicate the existence of an optimal cross-sectional area ratio, which maximizes the output power of the module. Moreover, this optimal cross-sectional area ratio demonstrates a linear relationship with both the module height and the exhaust heat transfer coefficient. A new design parameter f/(Lpn·hf) that incorporates both heat transfer and structural aspects is introduced. It finds that the optimal design parameter is f/(Lpn·hf) = 0.31 (m·K)/W, which allows the module to achieve the highest output power across all exhaust parameters. The results of this study offer valuable guidance for the refined design of the integrated systems.