Apparent thermal conductivity measurement of anisotropic insulating materials at high temperature by the parallel hot-wire method

This article presents a measurement method of the apparent thermal conductivities of anisotropic insulating materials at high temperature by the parallel hot-wire method. In the proposed variant, the temperature is measured simultaneously at two points located on the main axes of anisotropy of the material to be characterized. A comprehensive model taking into account the anisotropy, the thermal capacity of the heating wire and the contact resistance was developed. A method for the estimation of the thermal properties was devised after carrying out a theoretical study of the reduced sensitivities of the temperatures to the different unknown parameters. An experimental study carried out up to 1000 °C on an anisotropic rigid insulating material confirmed that the thermal conductivities and the volumetric heat capacity of a rigid insulating material could be estimated by the proposed method with an accuracy of approximately 10%.