Effect of substrate layers on thermo-electric performance under transient heat loads

Due to thermal resistance, the temperature difference between the hot and cold sides of thermoelectric elements and power generation in thermoelectric generators are affected by the module’s substrate. Moreover, there are various types of applications where thermoelectric generators operate under transient heat load, and other material properties of the substrates, such as heat capacity, have impact on temperature profile of the thermoelectric generator. This paper, therefore, aims to evaluate transient behavior of thermoelectric generator, affected by its geometry, under periodic and oscillated thermal loads in order to provide a link between the power output and power management of thermoelectric generators. A three dimensional COMSOL Multiphysics model of the thermoelectric generator is developed to evaluate performance of the module under transient heat loads, different substrate materials and thicknesses, and various coolant heat transfer coefficients. Results of the simulations, which are in a good agreement with experimental data, show that the rectangular heat load provides highest power generation between the investigated heat loads, and the thermoelectric generator with Kapton substrates produces maximum voltage oscillation amongst the studied substrate layers. The numerical results of this study conclude that, the material properties and thickness of the substrate have significant effect on the thermo-electric behavior under transient heat loads.