Performance analysis of a novel Two-stage automobile thermoelectric generator with the Temperature-dependent materials

•A novel two-stage automobile thermoelectric generator is designed and investigated.•The impedance matching condition for the maximum power is derived.•The temperature-dependent thermoelectric materials are considered.•The detailed comparisons with traditional configuration are conducted.•The designed two-stage configuration could achieve the power increments by 13.5%. In order to enhance the performance of the automobile waste heat recovery system, a novel two-stage automobile thermoelectric generator with a cascade configuration along the temperature gradient of exhaust gas was designed. The corresponding integrated one-dimensional numerical model considering temperature-dependent thermoelectric materials was developed to predict the performance accurately. The impedance matching condition for the maximum output power was derived for the novel two-stage automobile thermoelectric generator. The developed model was demonstrated through comparisons with the reported experimental data and simulation results. The results indicated significant discrepancies in output power, conversion efficiency, and the temperature difference between the cold/hot sides of thermocouples for single-stage and two-stage configurations. The designed thermoelectric generator with the two-stage configuration could capture the temperature change along the flow direction of exhaust gas and obtain better performance by adjusting the length of the two-stage module. Compared to the traditional single-stage thermoelectric generator, the designed two-stage configuration could achieve the output power increments by 13.5% under the same working conditions. The effects of working conditions (exhaust gas temperature and mass flow rate) and TEG geometry size on the output power are studied. This work could provide some guidance on the design and performance enhancement of automobile thermoelectric generators.