Exhaust heat harvesting of automotive engine using thermoelectric generation technology

Abstract

Exhaust heat recovery from internal combustion engines is growing interest to reduce fuel consumption, increase the efficiency and consequently, reduce the environmental pollution and global warming. Thermoelectric generator (TEG) is a promising technology to harvest engine exhaust heat by directly converting it into electrical power via the Seebeck effect. In this work, commercial Bi2Te3 (SP1848-27145 SA) thermoelectric modules (TEMs) were used for recovering exhaust heat from gasoline engines and convert it directly into electricity. Two types of setups were constructed using copper and steel materials, where both setups consist of triangular channels. The first setup was constructed entirely from copper material to work as a heat exchanger from exhaust heat to the TEMs’ hot surface. The second setup was constructed with a portion of copper at the installation area of TEMs and the rest of the portion was constructed with steel material to investigate the best performance from these two TEG systems. Six TEG modules which are electrically series connected were installed on the outer surfaces of each copper made and steel made setup. The maximum power output from copper made TEG was found to be 2.96 W for an exhaust temperature of 297 °C and at 126 °C temperature difference between the hot and cold sides. Whereas steel made TEG provided the maximum power output of 2.0 W for an exhaust temperature of 305 °C and at a 107 °C temperature difference between hot and cold sides. Therefore, the copper made TEG setup provided 48% higher power output than the steel made TEG setup. The higher power output of copper made TEG lowers the expelled exhaust temperature to the environment, which results in the decrease of entropy loss. Furthermore, since there is no effect of engine operating pressure on enthalpy loss, therefore, the engine can operate at higher operating pressure which means the contribution of the reduction of fuel cost, fuel consumption and environmental pollution parallelly. Between exhaust gas temperature ranges 297 °C to 300 °C, the highest conversion efficiency was found 4.65 % and 4.63% for steel made TEG setup and copper made TEG setup, respectively.