Finite-Element Simulations of a Thermoelectric Generator and Their Experimental Validation

Abstract

A versatile finite-element simulation tool was developed to predict the electric power output, the distributions of the electric and entropy potentials (i.e., the absolute temperature) and the local flux densities of electric charge and thermal energy (i.e., heat) for a thermoelectric generator. The input parameters are the thermogenerator architecture (i.e., geometries of different components and number of legs) and material properties such as specific electric conductivity, Seebeck coefficient and thermal conductivity. The finite-element simulation tool was validated by modeling a commercially available thermoelectric generator, which was based on semiconducting n- and p-type Bi2-xSbxTe3 with ceramic cover plates, and comparing the modeled voltage-current characteristics and power characteristics with experimental values for different temperature conditions. The geometric parameters could easily be determined from photomicrography and cross-sectional scanning electron microscopy observations. The electric conductivity and Seebeck coefficient were measured, as functions of temperature, from the integer module as leg-averaged values. The thermal conductivity was taken from literature data, which required estimating the compositions of components using energy-dispersive X-ray spectroscopy in the scanning electron microscope and their crystal structures using X-ray diffraction. Good agreement was found between the simulated and measured voltage-current and power-current characteristics. The finite-element simulation tool is versatile because it uses a script-based approach, which allows easy parameter changes and allows it to be adapted to thermogenerators consisting of different geometries and materials, including novel materials.