Performance Study and Optimization of a Polygonal Automobile Exhaust Thermoelectric Generator with Embedded Protrusions

To boost the power and conversion efficiency of a polygonal automobile exhaust thermoelectric generator (AETEG), an innovative protrusion-type disturbance is introduced to the original sickle-shaped fins in this work. A coupled multiphysics field model integrating fluid, thermal, and electrical fields was constructed, a net power framework was formulated, and the protrusion structure parameters of protrusion radius and spacing were optimized. At a flow velocity of 40 m/s and an inlet temperature of 600 K, simulation results reveal that increasing the protrusion radius and protrusion spacing effectively improves the heat capture capability and the overall performance of the AETEG system. Simultaneously, the backpressure inside the heat exchanger increases, accompanied by a decline in temperature uniformity at the hot side of the thermoelectric modules (TEMs). Based on the designed multiple performance metrics, the optimal protrusion configuration is finally set as R = 8 mm, Dtg = 8 mm, and Dhf = 5.5 mm. Compared with the original AETEG system with sickle-shaped fins, the optimized protrusion design enhances the TEMs’ average hot-side temperatures by 5.11%, increases the output power by 42.22%, and improves the net power by 76.48%. Additionally, this optimization results in a 13.44% improvement in conversion efficiency and a 40.65% enhancement in net efficiency.