Performance interaction assessment of automobile exhaust thermoelectric generator and engine under different operating conditions

Structure optimization of heat exchanger helps to enhance the output performance of thermoelectric generator (TEG) for automobile exhaust recovery, but the heat exchanger connected to the internal combustion engine (ICE) may lead to its large backpressure and deteriorative performance. To assess the performance interaction between automobile exhaust thermoelectric generator (AETEG) and ICE, the comprehensive numerical model of ICE integrated with AETEG of different heat exchangers was set up and validated based on a test setup. The results reveal that the ICE operating condition and inner topology have obvious influences on the backpressure of heat exchanger, and the chaos shape heat exchanger has the largest backpressure under the same ICE operating condition. The increased backpressure raises the pumping mean effective pressure (PMEP) of ICE, enhances the hot side temperature of TEMs and the maximum output power of AETEG, and the decreases the brake power, brake torque, volumetric efficiency and fuel economy of ICE. Besides, compared with the ICE without AETEG, the ICE emission of CO, CO2, NOX and smoke opacity from empty cavity shape and other heat exchangers increases. The influence of backpressure caused by the heat exchanger on the ICE performance is obvious at large ICE speed and output power. The finds provide a numerical investigation guide for the development, topology optimization and performance assessment of a low-backpressure AETEG without obviously deteriorating the ICE performance.