Thermal conductivity models of sandstone: applicability evaluation and a newly proposed model
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ORIGINAL
Thermal conductivity models of sandstone: applicability evaluation and a newly proposed model Yanjun Shen 1,2,3
&
Xu Wang 4 & Yongzhi Wang 4 & Keping Zhou 5 & Jinyuan Zhang 4 & Huan Zhang 4 & Jielin Li 5
Received: 7 November 2019 / Accepted: 3 November 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The thermal conductivity (TC) of rock has a general application in safety assessment and engineering optimization of deep geological engineering practices such as geothermal mining and nuclear waste disposal. Determining the TC of rock by using a TC model is a convenient and effective method for such evaluation, and selecting a suitable TC model is key for ensuring accurate calculation results. In this study, we firstly select eight two-phase TC models to evaluate the applicability to sandstone. Secondly, the TC values of sandstones in various porous media such as air, water, and ice are measured by using the transient plane source (TPS) method, and the mineral composition and content were determined by using Xray diffraction (XRD) and the Cross, Iddings, Pirsson, and Washington (CIPW) norm. Thirdly, the TC values of sandstones in different porous media are also calculated by using the eight models, and their deviations are analyzed to compare their applicability. Finally, by considering of the influence of pore structure on the rock TC, a new TC model referred to as the thermal resistance–connectivity (TRC) model is proposed for sandstone based on pore connectivity, and the mean deviation is compared with the previous model. Several results are obtained. Among the eight common models, the geometric mean model is found to be more accurate than other models regardless of all three states. In particular, for the porous medium filled with ice, the calculated value of the Geometric mean model had the most significant agreement with the measured value. In addition, the mean deviation of the TRC model for all three states is shown to be more consistent with the measured value than the eight models. Therefore, we recommended the TRC model for calculating the TC of sandstone. This study provides a novel method for determining the TC value for deep geological assessment. Keywords Sandstone . Thermal conductivity . Applicability, pore connectivity . Thermal resistance–connectivity (TRC) model
* Yanjun Shen [email protected]; https://orcid.org/0000-0001-8109-4819 Xu Wang [email protected] Yongzhi Wang [email protected]
1
College of Geology and Environment, Xi’an University of Science and Technology, Xi’an, Shaanxi 710054, People’s Republic of China
2
Geological Research Institute for Coal Green Mining, Xi’an University of Science and Technology, Xi’an, Shaanxi 710054, People’s Republic of China
3
Shaanxi Provincial Key Laboratory of Geological Support for Coal Green Exploitation, Xi’an, Shaanxi 710054, People’s Republic of China
4
School of Architecture and Civil Engineering, Xi’an University of Science and Technology, Xi’an, Shaanxi 710054, People’s Republic of Chin
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