Abstract
Internal combustion engines reject approximately one-third of fuel combustion energy directly into the environment through exhaust gases. Thermoelectric generators (TEGs) offer a promising solid-state route for recovering this low-to-medium-grade waste heat and converting it into auxiliary electrical power. In this study, an optimized multichannel hexagonal thermoelectric generator incorporating staggered internal pin fins and counter-flow liquid cooling jackets was developed and evaluated on a 1.6-liter turbocharged gasoline direct-injection engine test bench. Sixteen high-performance bismuth telluride (Bi2Te3) modules were strategically arranged along the exhaust flow axis to assess thermal uniformity, interfacial contact pressures, and thermo-hydraulic trade-offs. Experimental evaluations conducted across engine speeds ranging from 1500 to 3500 rpm revealed that the optimized internal fin geometry increased the hot-side heat transfer coefficient by 42% while constraining exhaust backpressure below 2.85 kPa. Under high-load operating conditions, the system established a sustained temperature differential of 194.2 °C across the thermoelectric modules, yielding a maximum gross electrical power output of 348.6 W and a net system power output of 312.4 W after deducting parasitic pumping losses. The corresponding thermoelectric conversion efficiency reached 4.62%, demonstrating that strategic aerodynamic fin tailoring combined with dynamic clamping pressure substantially enhances automotive waste heat recovery without compromising engine volumetric efficiency.
