Multi-factors analysis of energy conversion enhancement of thermoelectric generator for exhaust waste heat recovery

To enhance the energy efficiency of waste heat recovery, an optimized two-stage thermoelectric generator is developed through coordinated structural design optimization and operating parameter setting. A three-dimensional numerical model with conjugate heat transfer is employed to investigate the effects of exhaust gas velocity, fins height, cooling water velocity, and heat pipe configuration on system performance. Results indicate that increasing the exhaust gas velocity enhances power output but also intensifies heat loss. Optimizing the height of inserted fins improves gas-solid heat transfer and temperature uniformity, thereby raising the hot-side temperature of thermoelectric modules. A higher cooling water velocity improves cold-side heat dissipation, while excessive flow rates yield diminishing returns and impose higher loads on the water-cooling system. Additionally, the integration of heat pipes significantly improves heat recovery efficiency and expands the effective hot-side area, enabling higher electrical output. Further analysis indicates that performance gains from increasing the number of heat pipes become marginal beyond a critical value. Through coordinated optimization of fin setting, heat pipes number, exhaust gas velocity, and cooling water flow rate, the system performance is substantially improved. When V e = 16 m/s and T e = 600 K, the thermoelectric generator with 12 heat pipes and PbTe-Bi 2 Te 3 two-stage modules achieves an electric power output 84.88 W and system efficiency reaches 2.7%. These findings provide design guidelines for high-efficiency thermoelectric generator and demonstrate strong potential for automotive waste heat recovery applications.