Experimental analysis of exhaust energy recovery performance of an internal combustion engine using thermoelectric generators and fuel economy evaluation

This research examines the incorporation of thermoelectric generators (TEGs) into the exhaust systems of internal combustion engines to recover waste heat. The study employs a three-cylinder Yanmar diesel engine to evaluate the energy conversion efficiency of two layers of TEGs placed between a brass heat exchanger (HEX) and aluminum water coolers. As the author's knowledge is applied for the first time, a new zigzag HEX, new cooling blocks, and a new high-voltage Canadian (TEG1-24111-6.0) enhance thermal performance. Simultaneously, the cooling system maintains a consistent temperature gradient across the TEGs. Experiments were performed using thirty bismuth telluride-based TEGs connected electrically in series, yielding a peak gross power output of 259.01 W at 2400 rpm under steady-state conditions. The research analyzed five engine scenarios with varying running speeds (1900, 2000, 2125, 2250, and 2400 rpm) and load conditions. Results highlight the significant influence of engine speed, HEX design, and cooling efficiency on TEG performance. It was concluded that the engine brake specific fuel consumption with TEG integration is lower than that of the engine lacking TEGs, approximately 2.317 % at 2400 rpm.