Experimental investigation on rock thermal properties under the influence of temperature

Abstract

The rock thermal parameters is of basic interest in geophysical, underground and engineering applications. The most relevant properties are thermal conductivity, specific heat capacity and thermal diffusivity. The present paper focuses on thermal properties of several rock types and minerals under the influence of temperature. On one hand, we provide a detailed review of rock thermal parameters and available correlations, and on the other hand, a series of laboratory measurements are presented and data are analyzed. For specific heat capacity measurements at atmospheric pressure and over a temperature range from 20 to 600 °C, the Differential Scanning Calorimetry (DSC) method is used and an indirect method is proposed. The results demonstrated an increase of specific heat capacity with a second order polynomial regression. The thermal conductivity and thermal diffusivity were investigated between 20 and 180 °C using the Hot Disk method. A logarithmic decrease with temperature was observed. In addition, a simple and inexpensive apparatus for measuring thermal conductivity at room temperature (20.0 ± 0.2 °C) is described and the results are compared with the commercial device. The results showed good performance with the estimated errors below 10%. To improve the applicability of the obtained results, empirical equations are developed to predict the thermal properties as a function of temperature and other physical properties. It was observed that the empirical relationships and the predicted values by the proposed equations are in agreement with the experimental data and with literature. Research results in this paper can be used as a support for rock engineering and a solution of a range of scientific and applied problems.