Thermophysical Properties of Diorites along with the Prediction of Thermal Conductivity from Porosity and Density Data

Abstract

The main focus of this paper involves the use of models to predict the thermophysical properties of diorites. For the prediction of thermal conductivity, an existing mixing law and empirical models have been used. Due to the porosity dependence in all the existing models, ASTM (American Society for Testing and Materials) standard methods have been applied to measure the density, porosity, and specific gravity of diorite rocks taken from the Shewa-Shahbaz Garhi volcanic complex near Mardan, Pakistan. The chemical composition of these samples has been analyzed using the X-ray florescence technique. The theoretically calculated values of specific gravity and the density of the specimen based on the chemical composition and porosity are in good agreement with those obtained from experimental measurements at ambient conditions. The thermal conductivity and thermal diffusivity of these rocks have been measured simultaneously using the transient plane source (TPS) technique at room temperature. The effective thermal conductivity calculated from various models is in agreement with the experimental data within 15%. Simple correlations between estimated density and porosity and between the effective thermal conductivity and porosity are also established.

The mechanism of granite breaking by electric pulse under high temperature and high pressure environment

“…In discussing the thermal expansion process in the process of electric pulse rock breaking, only the rock is analyzed to simplify the calculations. The controlling equation for the thermal expansion process is the elasticity equation (Hooke's law), 4 𝜎 th = 𝐂 ∶ 𝜀 th (32) where 𝜎 th is the thermal stress, Pa;𝐂 ∶ is the isotropic elastic matrix, which is a function of the material elastic modulus 𝐸 t (Pa) and Poisson's ratio 𝜇, which is,…”

“…When the high‐voltage electric pulse is applied to HDR, the stratum temperature and the sharp increase in temperature within the rock will lead to irreversible changes in the rock properties 30,31 . The rock's thermal conductivity and heat capacity are the most relevant parameters in heat transfer, 32,33 and both reflect the material's ability to store and conduct heat. Knowledge of rock heat capacity and thermal conductivity variations is required in industrial processes and modeling methods for geothermal calculations 34 and geothermal field studies 35 .…”

Prediction of thermal conductivity of rocks by soft computing

“…Temperature changes induce thermal stresses causing thermal strains in the rock and concrete of structure (Verma 2000). The most important thermal properties of rocks are the thermal conductivity, heat capacity, and thermal diffusivity (Gul and Maqsood 2006). The first two parameters exhibit the capacity of a material to conduct or transmit and accumulate heat, respectively; and the last one gives an estimate of what area of the material has been affected by the heat per second.…”

Modeling of the Effective Thermal Conductivity of Consolidated Porous Media with Different Saturants: A Test Case of Gabbro Rocks

“…To make laboratory measurements on all types of rocks of interest and under all environmental conditions of temperature, pressure, and fluid saturation would be prohibitive in terms of time and expense. Consequently, a lot of effort [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] has been made to devise a simple physical model for the prediction of thermal conductivities of porous rocks filled with fluids ranging in thermal conductivity from that of air to that of water.…”