Multiphysics simulation and optimization of baffle geometry for enhanced performance in automotive thermoelectric generator systems

• A fluid-thermal-electric model is used to optimize exhaust channel baffle layouts. • Sparing upstream while densifying downstream baffles boosts overall power output. • Adjusting baffle angles balances heat transfer gains and backpressure losses. • Proposed designs achieve up to 15.95% net power improvement over uniform layouts. Automotive thermoelectric generator (TEG) systems provide a promising avenue for waste heat recovery, yet their overall performance is heavily influenced by heat exchanger geometry. In this work, a fluid-thermal-electric multiphysics model is developed in COMSOL to systematically evaluate seven distinct baffle layout strategies, i.e. one uniform arrangement and multiple non-uniform variants, and to explore baffle angles ranging from 30° to 160°. Key performance indicators include TEG output power, backpressure power loss, net output power, and conversion efficiency, as well as voltage uniformity across thermoelectric modules. Results show that placing more baffles in the downstream portion of the exhaust channel increases total power output by creating higher near-wall gas temperatures. Conversely, concentrating baffles primarily in the upstream section helps reduce backpressure losses, thus elevating the net output power. Among the tested configurations, one arrangement with denser baffles upstream achieves a net power of 18.03 W at an exhaust inlet temperature of 650 K, indicating 15.95% higher than the uniform arrangement. Another non-uniform layout achieves the highest conversion efficiency of 1.86% at the same temperature. Moreover, varying the baffle angle reveals an initial rise and subsequent fall in output power, backpressure loss, and heat absorption. At a 160° angle, the system attains a maximum net power of 10.29 W at 550 K, alongside a conversion efficiency of 1.37%. These findings highlight the importance of balancing heat transfer enhancement against exhaust flow resistance and provide valuable guidelines for optimizing baffle geometry and placement in automotive TEG systems.