Study on heat exchanger structural optimization of stationary engine thermoelectric generator system

Thermoelectric generators have received considerable involvement in recovering the wasted heat from internal combustion engines (ICE). However, the power of the thermoelectric generator system (TGS) on an ICE is minimal compared with the exhaust energy. This study investigates the effects of heat exchanger structural parameters, including the fin quantity, fin height, and fin thickness, on the performance of the TGS utilizing the emission gas from a stationary diesel engine to find the optimal set of parameters that produce the maximum performance. The numerical method is adopted to determine the total output and pressure loss powers of the TGS with various fin quantities, heights, and thicknesses at three engine operating modes. The tradeoff ratio is utilized to compare the performances of different TGS structures to account for their pressure drop effect on engine power reduction. The results reveal that the output power of TGS increases when the fin quantity, thickness, and height rise. However, when the number of fins is large enough, it reduces with the rise of fin height. Pressure loss increases with the increasing fin quantity and thickness but decreases with increasing fin height. The set of optimal parameters found in this work is the heat exchanger with 28 fins, a fin height of 40 mm, and a fin thickness of 1 mm. Thanks to the optimal heat exchanger, the TGS output power increased to 45.39% compared with the worst case in the considered range. This optimization is necessary because it achieves the highest performance and makes the TGS more compact and affordable price. This result is the critical basis for designing and manufacturing the TGS prototypes for future experimental studies.