Measurement of the Effective Thermal Conductivity of Powders Using a Three-Layer Structure

Abstract

This article deals with the experimental measurement of the effective thermal conductivity of powders using a photothermal method with a crenel heating excitation. This method represents an improvement of the technique presented in a preceding article. It consists of applying a heat flux on the front face of a three-layer structure and recording the temperature on the rear face using a Tellure of Bismuth thermocouple. The powder is poured into a Teflon cell which is closed by two thin copper layers. Measurements are reported on several powders with spherical particles. The parameter identification is performed by the minimization of the ordinary least squares objective function, comparing the measured temperatures to the response of a thermal model built by the thermal quadrupole formalism. The used iterative algorithm is based on the Gauss-Newton method.