Evaluation of thermoelectric generators for automotive waste heat recovery

Thermoelectric generators (TEGs) are increasingly investigated for automotive exhaust waste-heat recovery in response to stringent fuel-efficiency regulations. This study numerically examines an air-cooled hybrid annular–rectangular TEG configuration integrated with external heat-sink modules to evaluate system performance under realistic automotive operating conditions. A three-dimensional numerical model was developed using COMSOL Multiphysics to investigate the influence of exhaust gas temperature (350–550 °C), exhaust mass flow rate (10–30 g/s), ambient air temperature (5–45 °C), and vehicle speed (40–120 km/h) on conversion efficiency and power output. The results show that the system achieves a maximum conversion efficiency of 12.3% at an exhaust temperature of 550 °C, an exhaust mass flow rate of 16 g/s, an ambient temperature of 5 °C, and a vehicle speed of 120 km/h, corresponding to an electrical power output of 314.7 W. Under maximum power conditions, increasing the exhaust mass flow rate to 30 g/s yields a peak power output of 559.3 W and an efficiency of 11.7%. Under representative automotive operating conditions (450 °C exhaust temperature, 20 g/s exhaust mass flow rate, 25 °C ambient temperature, and vehicle speed of 80 km/h), the system delivers 141 W of electrical power at an efficiency of 5.8%. The integration of air-cooled heat sinks enhances thermal dissipation while maintaining a pressure drop below 0.3 kPa, indicating a negligible impact on engine performance. These results demonstrate the feasibility of compact, air-cooled TEG systems for automotive waste-heat recovery and provide quantitative guidance for system-level design and optimization.