Development of a multi-physics numerical model for a multi-component thermoelectric generator with discontinuous porosity in the exhaust gas channel

Abstract

A critical technical challenge in the energy harvesting performance of a thermoelectric generator (TEG) is the optimal utilization of the thermal energy from exhaust gas. In most TEG applications, the exhaust gas flowing through the exhaust channel exhibits high inertia forces, causing significant temperature maldistribution on the hot surfaces of thermoelectric modules (TEMs). To address this challenge, we developed a numerical model that incorporates the primary multi-physics phenomena associated with TEGs, designed with a porous flow conditioner and extended surfaces for practical use. A reliable three-zone method is employed to simulate thermoelectric energy conversion phenomena, including the resulting heat pumping and Joule heating effects in individual TEMs. The model accounts for the communication effect between electrically connected TEMs by integrating Kirchhoff’s voltage and current laws into the solving process. A selective porous media method is proposed for accurately analyzing the pressure jump induced by the flow conditioner and the porosity jump occurring at the interfaces between the flow conditioner and plate fins while ensuring model convergence reliability. The developed numerical model aligns with experimental results, showing a maximum error of 5 %. Comprehensive analyses of TEM-wise heat absorption rates and channel-wise flow distribution characteristics were conducted to identify the optimal position and porosity of the flow conditioner. The findings demonstrate that optimal use of the flow conditioner improves the net output power of the TEG by 31.5 % compared to the case without any flow conditioner.