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Relationship between thermoelectric figure of merit and energy conversion efficiency

2015; National Academy of Sciences; Volume: 112; Issue: 27 Linguagem: Inglês

10.1073/pnas.1510231112

1091-6490

Hee Seok Kim, Weishu Liu, Gang Chen, C. W. Chu, Zhifeng Ren,

Thermal properties of materials

Significance Thermoelectric materials generate electricity from temperature gradients. The dimensionless figure of merit, ZT = S 2 ρ −1 κ −1 T , is calculated from the Seebeck coefficient ( S ), electrical resistivity ( ρ ), and thermal conductivity ( κ ). The calculated efficiency based on ZT using the conventional formula is not reliable in some cases due to the assumption of temperature-independent S , ρ , and κ . We established a new efficiency formula by introducing an engineering figure of merit ( ZT ) eng and an engineering power factor ( PF ) eng to predict reliably and accurately the efficiency of materials at a large temperature difference between the hot and cold sides, unlike the conventional ZT and PF providing performance only at specific temperatures. These new formulas will profoundly impact the search for new thermoelectric materials.