Analytical evaluation of non-Fourier heat pulse experiments on room temperature

Abstract

The classical constitutive equation for heat conduction, Fourier's law, plays an important role in the engineering practise and can be applied only for homogeneous materials. However, most of the materials consist of heterogeneity, such as porosity, cracks, or different materials are in contact.We used heat pulse measurement method (“flash method”), a standard method in the engineering practise, to measure the thermal diffusivity of each rock sample. During the heat pulse experiment the pulse reaches the front of the sample and the temperature of the rear is measured with a thermocouple. This is a common method to determine the thermal diffusivity of a material on room temperature. We found that the rear side temperature history can deviate from the one predicted by Fourier's law. Therefore, in the evaluation of the experimental data, we used an analytical solution of a non-Fourier model, called Guyer-Krumhansl equation. We present the measurement methodology and data recorded together with the evaluation procedure.