Temperature dependence of thermal conductivity, diffusion and specific heat capacity for coal and rocks from coalfield

The thermal properties of coal and rocks play an important role in the development of coalfield fires, head flow and the inversion of temperature. In this study, the thermal diffusivity and specific heat capacity were measured for bituminous coal from 25 to 300 °C, and sandstone and granite from 25 to 1000 °C using the laser-flash apparatus LFA457. The samples were taken from the Wuda coalfield. Combined with density data, thermal conductivities were then calculated. The results suggest that the method is able to accurately determine thermophysical properties for rocks in the temperature range of Earth's deep interior. When the temperature increases, thermal diffusivity and thermal conductivity decrease, and the decreasing thermal conductivities are generally linear. At high temperatures, thermal diffusivity and thermal conductivity approach constant values.