Computational Design for Functionally Graded Thermoelectric Materials
Year: 1999
Type: article
Abstract: In order to improve the conversion efficiency of thermoelectric (TE) materials and devices, computational study was performed for two different concepts of FGM configuration (1) TE FGM Power Device with Graded Dopant Density In order to design optimum dopant density distribution, precise estimation of transport properties and optimization of the carrier conduction mechanism are required. A model of thermoelectric materials is presented for transport properties of heavily doped semiconductors, and electron/phonon transport coefficients are estimated using band theory. Then, optimum dopant distribution is calculated in view of maximizing energy conversion efficiency. Simultaneously, thermal stresses induced by the high temperature gradient within the TE device should be reduced. Since the intemal physics is a coupled phenomena of heat flux and electric current, 2D Finite Element Method (FEM) is applied for the coupled analyses. The thermal stresses are calculated by 2D plane strain FEM for 3 stage cascade and segmented modules (2) Multi-layered Thermoelectric Material with Graded Potential Barriers A very different approach to increase the conversion efficiency is utilization of potential barriers. Since potential barriers act as carrier energy filters, elimination of lower energy carriers results in an improvement of the efficiency of thermoelectric energy conversion (energy filtering method). It has been shown that the characteristic energy range of carriers can be defined for thermoelectric energy conversion. From the knowledge of this characteristic energy range, the concept of graded control of microscopic physical quantities for optimizing the efficiency is clarified. The optimal height of potential barriers and the distance between the barriers are estimated within a semi-classical framework, i.e. using Boltzmann equation The method of improving the efficiency by using the multi-layered materials is proposed and the graded design of barrier layers is presented.
Source: Materials science forum
Authors: Toshiyuki Hirano, J. Teraki, Y. Nishio
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W2163382280