Thermoelectric properties and power generation of a p-Ca3Co4O9/n-CaMnO3 module

Author(s): Weerasak Somkhunthot*, Wattanapong Swang, Acharee Tunkasikit

An oxide thermoelectric module has been designed and constructed for electrical power generation. The device composed of thirty-one pairs of p- Ca3Co4O9 and n-CaMnO3 bulks, ceramic plates, and copper electrodes. Dimensions of both oxide legs were 2.0 mm thick and high and 1.0 mm wide, which were made from powder precursors, obtained from the solid state reaction method. The ceramic plates possessing dimensions 24.5 mm wide and long and 1.0 mm thick were used as substrate. The copper sheets 1.0 mm in width, 2.0 mm length, and 0.05 mm in thickness were attached onto the ceramic plates using epoxy adhesive to maintain achieve electrical conduction. The p-n legs and copper sheets on the ceramic plates were adhered by silver paint. For the measurements of thermoelectric properties at room temperature in air, both bulks showed the low Seebeck coefficient, high electrical resistivity, and large thermal conductivity, which lead to a lowpower factor and figure ofmerit. For the preliminary test, the module was used for thermoelectric power generation. The result shows linear dependence between the thermoelectric voltage and temperature difference. This device could generate up to 50 mV of open circuit voltage at hot-side temperature of 423 K and cold-side temperature of 343 K. The internal resistance of the module reached a value of 968.45 k. However, the module built could be used to generate lowthermoelectric power. The doped metals have been expected to be one of the candidates for good thermoelectric generators. Thiswill be further investigated.

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