Description of a 3D transient model to predict the performance of an experimental Thermoelectric Generator under varying inlet gas conditions

Abstract

The main challenge of working with thermoelectric generators lies in their low efficiency, so finding the optimal design to achieve the best thermoelectric generator (TEG) performance under the working conditions becomes a strong problematic. In this study, a numerical transient simulation tool was developed using different modelling techniques to achieve the performance improvement of a TEG. This TEG is composed of thermoelectric modules wrapped between two heat exchangers. A three-dimensional heat transfer transient model was first developed for the heat exchanger using the finite volume method and then coupled with a thermoelectric generation model. Materials properties vary as a function of temperature and the Thomson effect is taken into account to be able to get numerical results close to reality. Thermoelectric modules properties used in this model are those given by the manufacturer. The originality of this study is that it takes into account unsteady-state conditions, necessary for simulating a multitude of processes like the automobile (engine and exhaust systems), combustion processes, turbines working conditions and energy production. The use of this numerical tool can help maximize the TEG performance and possibly reduce material cost. In order to validate the model, the TEG has been built with the capacity of using different module quantities for different configurations. Experiments have been conducted at different inlet gas conditions (mass flow rate and inlet temperature). A comparison of experimental and predicted values of temperatures and output electrical power has been done in steady state regime. Using the three dimensional model for the heat exchanger, a good precision of the thermoelectric power generation model is obtained.