Estimation of thermophysical properties by an inverse method with experimentally determined heating region of a thin-layer heater

This paper deals with the problem of estimation of thermophysical parameters by an inverse method. The thermal conductivity in radial and axial direction of a cylindrical sample and the heat capacity were simultaneously estimated using the Levenberg–Marquardt method of minimizing a mean square functional. As heat sources the thin-layer heater KHR 2/10 of diameter ϕ = 50 mm and thickness 0.20 mm made by OMEGA as well as the Kanthal resistance wire of diameter ϕ = 0.1 mm in a form of semicircle were simultaneously used. The main aim of using these two heaters simultaneously, both placed at one of the sample interfaces, was to generate heat fluxes in axial and additionally in radial direction. However, measurements of temperature distribution on the main surface of the thin-layer heater by using the FLIR Systems (ThermaCAM SC 3000 infrared camera) revealed a spatial heterogeneity of its temperature field, and therefore it was necessary to determine the effective heating region of that heater indispensable for solving of the coefficient inverse problem of heat conduction.