Characterizing the dynamic response of a sickle-shaped fins based octagonal AETEG system optimized with protrusions: Insights from different driving cycles

Recovering waste heat from automotive exhaust to generate electricity and applying the automotive exhaust thermoelectric generator (AETEG) system to vehicles can effectively improve the fuel economy. However, existing steady-state analysis methods cannot accurately predict the dynamic characteristics of the AETEG system for automotive applications. Based on a heat exchanger using sickle-shaped fins optimized with protrusions, this study developed an octagonal AETEG system, and established a transient flow-thermal-electric multiphysics coupling model using COMSOL software. According to the VEH_LGCAR vehicle model created in ADVISOR, the transient flow-thermal and thermal-electric output performance of the proposed AETEG system was comprehensively evaluated under three typical driving cycles including China Light-Duty Vehicle Test Cycle (CLTC), New European Driving Cycle (NEDC) and Highway Fuel Economy Test (HWFET). Comparative results demonstrate that the average errors between the simulated and experimental values for dynamic output power and voltage are 5.91% and 4.98%, respectively, indicating that the developed transient flow-thermal-electric multiphysics coupled model is effective and feasible. Under different driving cycles, significant differences exist in the average and peak transient performance. The highest peak transient conversion efficiency of 1.58% and average transient conversion efficiency of 0.43% are achieved under CLTC driving cycle, and the maximum output voltage of 128.56 V and maximum output power of 82.64 W are produced under NEDC driving cycle. Under HWFET driving cycle, the average voltage and output power reach 78.24 V and 39.76 W, respectively. This work provides effective methodological guidance for the in-vehicle application of AETEG systems and the analysis of their transient characteristics.