Effect of High Temperatures on the Thermal Properties of Granite

On the temperature and pressure dependences of the effective thermal conductivity of granites

“…The dashed curve shows the dependence calculated according to the Debye theory (the Debye temperature corresponding to the experimental data is close to 670 K). As we can see both curves are very close to experimental data and unlike [11] we haven't seen any features.…”

“…In a very recent work [11] devoted to the study of the temperature properties of granites, the obtained temperature dependence is quite different from the power law (1). Nevertheless, the decreasing nature of the dependence, taking into account a rather large error, the data presented can be approximated by the eq.…”

“…The temperature of this transition is 845 K at atmospheric pressure and increases to 945 K at 375 MPa. [21] As revealed in [11], cracks probably associated with this transformation begin to appear after ~ 500 K and begin to be significant after 750 K. Between 900 K and 1150 K cracks do not change much, but the number of cracks gradually increases. Meanwhile, the connectivity of cracks is slowly increasing.…”

“…At higher temperatures the partial melting leads to the thermal damage. [11] On the other hand, it must be taken into account that the melting temperature (including partial) of a complex composite compound can decrease with increasing pressure, especially with significant fluid and moisture saturation. In the outlined pressure range (up to 400 MPa), the experimental temperature dependence taken at atmospheric pressure and sufficiently well obeying the power law up to ~ 800-900 K (see, for example, [22]) can give the possibility for the sufficiently reliably estimation of the effective thermal conductivity in a wide PT-range using the pressure dependences ) (P n and ) , ( 0 P T  obtained at relatively lower temperatures.…”

“…Most of the works, including recent ones [8][9][10][11], are aimed at studying only the effect of temperature on the effective thermal conductivity of rocks. As a result, thermal properties of rocks at various depths of the earth's crust are estimated without taking into account rock pressure.…”