Figure of merit ZT of a thermoelectric device defined from materials properties

• Published in: Energy & environmental science Vol. 10; no. 11; pp. 2280 - 2283
• Main Authors: Snyder, G. Jeffrey, Snyder, Alemayouh H.
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2017
• Subjects: Approximation; Electrical resistivity; Figure of merit; Heat conductivity; Historical account; Mathematical analysis; Seebeck effect; Temperature; Temperature dependence; Temperature effects; Thermal conductivity; Thermoelectric generators; Thermoelectric materials
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/C7EE02007D

While the thermoelectric materials figure of merit is a well defined metric to evaluate thermoelectric materials, it can be a poor metric for maximum thermoelectric device efficiency because of the temperature dependence of the Seebeck coefficient S , the electrical resistivity ρ , and the thermal conductivity κ where T is the absolute temperature. Historically the field has used a thermoelectric device figure of merit ZT to characterize a device operating between a hot side temperature T h and cold side temperature T c . While there are many approximate methods to calculate ZT from temperature dependent materials properties, an exact method is given here that uses a simple algorithm that can be performed on a spreadsheet calculator. The figure of merit is defined for a thermoelectric generator using the maximum efficiency of the thermoelectric device η calculated from the exact method.