The thermo-emf ΔV of the touching p- and n-type Cu/Bi-Te/Cu composites with different thicknesses of tBi-Te and tCu was measured as a function of time by alternating the temperature difference ΔT at periods of T = 20, 60, 120, 240 and ∞ sec, where tBi-Te was varied from 0.1 to 2.0 mm and tCu from 0 to 4.0 mm. As a result, ΔV changes significantly with tBi-Te, tCu and T. The effective thermo-emf ΔVeff increases significantly with an increase of 1/T and exhibited a local maximum at 1/T = 1/240 s−1. The resultant | α | and the effective temperature difference ΔTeff were increased significantly by optimizing tBi-Te and tCu at 1/T = 1/240 s−1. The power generation ΔWeff (= ΔVeff2/4Rcalc) estimated using the measured ΔVeff and calculated Rcalc also exhibited a local maximum at 1/240 s−1 for an optimum combination of tBi-Te = 0.1 mm and tCu = 2.0 mm, so that the maxima ΔWeff at 1/T = 1/240 s−1 for the p- and n-type composites were 2.28 and 2.92 times higher than those obtained at 1/T = 0 s−1. This significant increase in ΔWeff is owing to both the increase in ΔTeff and the increase in ZT due to the increase in |α|. The power generation was thus found to be enhanced significantly by imposing the alternating temperature gradients on touching Cu/Bi-Te/Cu composites.
Seebeck Coefficient Thermoelectric Material Energy Conversion Efficiency Thermoelectric Generator Contact Electric Resistance
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