Performance optimization for a combustion-based micro thermoelectric generator with two-stage thermoelectric module

Highlights: • A variable parameter thermoelectric module optimization program was developed. • Two-stage thermoelectric module boosts the conversion efficiency greatly. • The optimal device efficiency cannot be obtained while the power density is pursued. The program can optimize the most suitable resistance ratio under various conditions. In order to improve the efficiency of thermoelectric systems based on hydrocarbon fuel combustion on a micro scale, simulation models with variable temperature parameters are proposed. The objective of this research is to quantitatively study the effects of the key parameters of TE on the performance of micro thermoelectric generator. A model in which the temperature at the hot and cold ends varies with the optimization of the thermoelectric module is used. The results show that the two-stage thermoelectric module design results in lower combustor thermal efficiency, but greatly boosts the thermoelectric module conversion efficiency. So the overall efficiency of two-stage system is much higher than that of single-stage. Larger height and cross-section area of thermoelectric leg helps improve the efficiency but is not conducive to the miniaturization of micro thermoelectric generator. Especially, the ratio of external resistance to internal resistance of the micro thermoelectric generator is optimized between 1.2 and 1.65 due to the finiteness of the heat source. This work can provide guidance for improving the efficiency of two-stage combustion-based micro thermoelectric generator.