Description of the temperature-pressures dependence of thermal conductivity of natural and artificial composites

Аuthors

Emirov S. N.¹, Alkhasov S. M.¹, Beybalaev V. D.^{1, 2}, Amirova A. A.³, Gadzhiev G. G.³, Aliverdiev A. A.^{1, 2}

1. Institute for Geothermal Researches DSC of Russian Academy of Sciences , Makhachkala, 367030, Russia
2. Dagestan State Technical University, Makhachkala, 367000, Russia
3. Institute of Physics DSC of Russian Academy of Sciences, Makhachkala, 367015, Russia

Abstract

The article presents the analysis of thermal conductivity of natural and artificial composite materials samples. The experimental dependences, obtained by the absolute stationary method for the rocks such as sandstone, granite, marlstone, as well as mica-ceramic and CdGeAs2 semi- conductor compound, were considered. These dependencies were obtained within the temperature range of 273–523 K at hydrostatic pressure of 0.1–400 MPa. The experimental error of the method did not exceed 3–4%. For all considered samples the power-law temperature dependence of the thermal conductivity at a fixed pressure was found in the whole considered pressure range. It was also established that the increase in pressure leads to a decrease in the thermal conductivity temperature dependence due to the power index of temperature dependence de- crease. With this, for some compounds the power index of temperature dependence decrease with pressure bears linear (quasi linear) character within the whole range of 0.1–400 MPa, while for other compounds the fast change to 100–150 MPa occurs, after which the value of the power index of temperature dependence changes slightly. The second behavior is observed primarily for the compounds with a small absolute value of the index. The analysis of the isothermal baric dependence of the thermal conductivity revealed that for most compounds it could be described by a two-parameter power law. Thus, we have proposed a low-parameter equation for the temperature-pressure dependence, which well describes all experimental results. These dependence parameters were computed from the experimental data by the least squares method.

Keywords:

thermal physics, thermal conductivity, composite materials, heat transfer processes, high pressures, equation of state

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