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

Abid

Advances in Materials Science and Engineering

et al. 2020

Accurate values of thermal properties of rocks are needed for a number of engineering applications starting from heat losses in buildings to underground geothermal modeling. Igneous rocks are one of the major constituents of the Earth’s crust and are formed by the crystallization and solidification of molten magma. In this work, the thermal transport properties of porous igneous basalt rocks are measured using Transient Plane Source (TPS) technique under ambient conditions with air as saturant in pore spaces. Data are presented for fifteen samples of volcanic basalt rocks having different porosity values ranging from 0.267% to 9.432% by volume, taken from the place of Warsak near Peshawar city, located in the north of Pakistan. The porosity and density parameters are measured using the American Society of Testing and Materials (ASTM) standards. The mineral compositions of the samples are analyzed by X-ray fluorescence (XRF) technique. The specific gravity is predicted using the chemical composition of basalts and is compared with the experimental results. The thermal conductivity and thermal diffusivity values of the measured samples are also predicted using the mixing law and empirical models and results are compared with the measured data. Results show that the thermal conductivity of the studies of basalt samples decreases with the increase in porosity values, whereas no significant change has been observed in the thermal diffusivity data. Measured data are significant for geothermal modeling and in predicting heat losses in buildings wherever basalt rocks are used.

Section: Resultsmentioning

confidence: 99%

“…where z is the empirical exponent [1]. Another point to be noted here is that all the empirical constants mentioned above are calculated by least-squares method.…”

Section: Effective Thermal Conductivity Prediction Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Measurement and Prediction of Thermal Conductivity of Volcanic Basalt Rocks from Warsak Area

Abid

Advances in Materials Science and Engineering

et al. 2020

“…Veerendra and Chaudhary model 56 empty circles). Figure 7 demonstrates that our predicted thermal conductivities for the case when no roughness is presumed are overestimated with regard to the experimental measurements.…”

Section: A Thermal Contact Resistance Simulationmentioning

confidence: 99%

Thermal conductivity of granular porous media: A pore scale modeling approach

2015

Pore scale modeling method has been widely used in the petrophysical studies to estimate macroscopic properties (e.g. porosity, permeability, and electrical resistivity) of porous media with respect to their micro structures. Although there is a sumptuous literature about the application of the method to study flow in porous media, there are fewer studies regarding its application to thermal conduction characterization, and the estimation of effective thermal conductivity, which is a salient parameter in many engineering surveys (e.g. geothermal resources and heavy oil recovery). By considering thermal contact resistance, we demonstrate the robustness of the method for predicting the effective thermal conductivity. According to our results obtained from Utah oil sand samples simulations, the simulation of thermal contact resistance is pivotal to grant reliable estimates of effective thermal conductivity. Our estimated effective thermal conductivities exhibit a better compatibility with the experimental data in companion with some famous experimental and analytical equations for the calculation of the effective thermal conductivity. In addition, we reconstruct a porous medium for an Alberta oil sand sample. By increasing roughness, we observe the effect of thermal contact resistance in the decrease of the effective thermal conductivity. However, the roughness effect becomes more noticeable when there is a higher thermal conductivity of solid to fluid ratio. Moreover, by considering the thermal resistance in porous media with different grains sizes, we find that the effective thermal conductivity augments with increased grain size. Our observation is in a reasonable accordance with experimental results. This demonstrates the usefulness of our modeling approach for further computational studies of heat transfer in porous media.

“…Thus, a good estimate of the thermal conductivity of scoria would probably be obtained. Another way to predict a K scoria value would be through the application of the most precise empirical models, which present low percentage of deviation respect to the experimental allotropic model, such as Assads's and Maxwell's models (Aurangzeb and Maqsood 2007).…”

Section: Notementioning

confidence: 99%

Evaluation of Jordanian Basalt as a Thermal Insulation Material

Pérez

2024

J. Ecol. Eng.

Finding a thermal insulation material that is naturally available, cheap, and effective for minimising energy losses is a challenge for geotechnical engineers in Jordan. Previous research suggests the use of mineral wool, polyurethane, or air layers as an insulation material but so far, the basalt has not been used as an insulation material in Jordan. The objective of this study was to measure and compare the thermal conductivity (K), bulk density (ρ B ), porosity (ɛ) and chemical composition of the basalt from Hashemiah area and Hulial mountain in Jordan in order to evaluate the rock as a thermal insulation material. A total of fourteen samples, seven for each zone, were evaluated. The thermal conductivity was measured using transient plane source technique (TPS) at ambient temperature. Porosity and density were measured by the standards of the American Society of Testing Materials (ASTM). The chemical composition of the samples was analysed by X-Ray diffraction to include the effect of aluminium oxide on thermal conductivity analysis. Experimental values covered the range of ɛ between 0.008-8.7%; ρ B between 2.54-2.93 g/cm 3 and K between 1.62-2.98 W/mK. The experimental K values were compared with allometric fit and theoretical prediction models. In general, thermal conductivity tends to decrease with porosity in basalt samples. This study found increasing conductivity values with ɛ when ferromagnesian-aluminium oxide concentration reached levels above 38% and porosity less than 4% indicating that high percentages of these oxides decrease the insulating effect of the air in the empty spaces of the basalt at reduced porosity levels. Low values of conductivity and percentage of ferromagnesianaluminium oxides characterise the Jordanian basalt in the Hashemiah area and makes it better for insulation than the Hulial mountain basalt. The experimental values presented in this work are important for predicting the optimum insulation thickness and predicting energy losses in construction buildings where basaltic rocks are used.