Dynamic behaviour of automobile thermoelectric waste heat recovery under different driving cycles

Abstract

Different types of vehicles often run in different driving cycles, resulting in different dynamic behaviours of the automobile thermoelectric generator. The dynamic performance of a simplified automobile thermoelectric generator under different driving cycles, including HWFET, NEDC, WLTP, and CLTC, is evaluated to guide the application of automobile thermoelectric waste heat recovery by a hybrid transient CFD-TE model. The model is experimentally validated with an average output error of 10.92%, mainly caused by the instrument error. The findings indicate that the response of the dynamic output power of the automobile thermoelectric generator exhibits smoother fluctuations compared to the exhaust temperature, and also displays hysteresis in its response, while the dynamic conversion efficiency experiences sharp fluctuations. The behaviour of the automobile thermoelectric generator in dynamic situations is not entirely proportional to the vehicle speed but is instead dependent on changes in vehicle speed, more specifically, the change of exhaust heat. By comparing the steady and dynamic results, it is found that the steady-state model overestimates the output power but may underestimate the conversion efficiency. The automobile thermoelectric generator is more suitable for vehicles with frequent speed changes, such as passenger cars on urban and suburban roads, to enhance the dynamic output performance.