Theoretical analysis of annular thermoelectric generators made of functionally graded materials

Abstract

In this study, the temperature field distribution and thermoelectric conversion efficiency of annular thermoelectric (TE) generators with functionally graded materials (FGMs) are investigated. The power series method is employed for solving a linear differential equation with variable coefficients to obtain temperature distribution, which has been proved to have good convergence and high precision. Numerical studies are carried out on FGM TE generators with linear and exponential variation, respectively. Material parameters that vary dependently and independently are discussed. If the figure of merit parameter Z keeps constant, then increases in the maximal conversion efficiency are not obvious. If material parameters vary independently, then the Seebeck coefficient increases from the cold temperature end to the hot temperature end and the maximal efficiency reaches 17.86%, which increases by 25.86% over 14.19% of homogeneous materials. For temperature-dependent TE materials, the problem could also be simplified to a functionally graded problem by presupposing an initial temperature field distribution. All these results give theoretical guidance for optimization of annular TE generators by using functionally graded structures.