MEASURING THERMAL CONDUCTIVITY OF MATERIALS BASED ON THERMOELECTRIC EFFECT

The aim of this work is to develop an apparatus for measuring the thermal conductivity of bulk materials based on steady-state method using a thermoelectric module (TEM). The cost-effective and easy purchased TEMs were utilized as the heating source, cooling source, and heat flux meter. The TEM was used to generate heating and cooling on the basis of the Peltier effect that involves with the conversion of electricity into thermal energy. On the contrary, the direct conversion of thermal energy into electricity based on the Seebeck effect was used as a principle to create a heat flux meter. For generation of heating or cooling, four TEMs, each with a dimension of 4 × 4 cm², were connected in a parallel circuit to serve as the heating and cooling sets. Each set directly contacted with each copper heat exchanger plate in a sandwich model with an 8 × 8 cm² sample material located at the middle. A TEM was embedded in the copper plate near the heating set for measuring the heat passing through the sample surface. To validate the accuracy of this apparatus, the thermal conductivity value of a polystyrene foam, which was tested according to ASTM C518, was compared with the value obtained by using an apparatus developed in this work. The results indicated that this apparatus gave high accuracy with an error of less than 0.87 %.