Efficient performance analysis and optimization of thermoelectric generators for low-grade heat sources: A simplified equivalent numerical modeling approach

Thermoelectric generators (TEGs) have garnered increased attention for utilizing various heat sources at different temperatures, ranging from industrial waste heat to geothermal energy. The characterization and optimization of the thermal-electric coupling performance of TEGs is of paramount importance and has been extensively explored by numerical modeling. However, the intricate geometric details of TEGs, which typically comprise hundreds of thermoelectric legs, result in significant computational complexity and time consumption. This paper introduces a simplified modeling method where each thermoelectric module (TEM) is treated as a representative block with equivalent thermal-electric properties. The proposed approach was validated through comparison with both experimental data and detailed modeling results, while significantly reducing the calculation time by a factor of 246. Using this simplified modeling method, the key factors contributing to TEG performance loss were identified, and several optimization strategies were investigated. Results show that incorporating metal foam into the heat sinks of the TEG system enhances the hydraulic-thermal-electrical performance. By optimizing the cooling water flow rate, the cold-side temperature of the TEMs was reduced by 4.77 K compared to the reference case at a heat source temperature of 373.15 K. This results in an output power of 4.66 W, a net power of 4.60 W, and a net efficiency of 1.20 %, which are increased by 13.0 %, 15.6 %, and 9.1 %, respectively. These findings validate the efficiency and effectiveness of this streamlined modeling approach for TEGs, offering a valuable strategy for performance analysis and design of large-scale devices.