Series-parallel resistance method based thermal conductivity model for rock-soil with low or high porosity

Jia, G.S.; D, Z; Zhang, Y P; Zhao, Min; Meng, Xiangzhao; Zhang, L Y

doi:10.1016/j.geothermics.2019.101742

Cited by 22 publications

(5 citation statements)

References 27 publications

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“…Figures 1(a) and (b) show the real structure and an equivalent structure of moist fibrous material. Using the thermo-electrical analogy technique, the solution of heat conduction problem for fibrous medium can be obtained by decomposing the complex fibrous structure into a network consisting of a set of series/parallel structural elements (figure 1(c)) [24,31]. Thus, in the study, the Parallel-Series model [23,32], which is a combination of the series l^and the parallel l p models, was applied to predict the ETC of fabric sample at different moisture content state as follows…”

Section: Theoretical Methodology 21 Effective Thermal Conductivity mentioning

confidence: 99%

“…A series-parallel hybrid models (^-) which assumed a cubical geometry were also developed by Krischer-Kroll [23]. In the hybrid model, volume fraction y of layers oriented perpendicular to the direction of heat flow is arranged in series with the complementary fraction (1−y) of layers oriented parallel to the direction of heat flow.The hybrid model has found successful predictions in fibrous moist building materials and unsaturated soils of layers oriented parallel to the direction of heat flow.The hybrid model has found successful predictions in fibrous moist building materials and unsaturated soils [10,24,25].…”

Section: Introductionmentioning

confidence: 99%

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Investigating the effective thermal conductivity of moist fibrous fabric based on Parallel-Series model: a consideration of material’s swelling effect

Zhu

2020

Mater. Res. Express

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The aim of this work reported in the paper is to investigate the influence of moisture content on the effective thermal conductivity (ETC) of non-hygroscopic Polyethylene terephthalate (PET) and hygroscopic Viscose (VC) fabrics using Parallel-Series (P-S) thermal-electrical analogy method and TPS measurement. An equivalent porosity for hygroscopic fabric was first proposed to preserve the validity of the P-S model. The equivalent porosity is characterized by reasonably eliminating the absorbed moisture effects partly, which is embodied in enhancing heat conduction, endothermic reaction and swelling. Calculated values of the effective thermal conductivity of the two kinds of fabrics had been compared with experimental measurements. Results show that the P-S model incorporated with equivalent porosity is found to yield higher prediction accuracy than that of P-S model with parent porosity. The calibrated model can also provide a robust tool for predicting the global effective thermal conductivity of moist hygroscopic fibrous porous media. Nomenclature P-SParallel-Series ETC Effective thermal conductivity ΔP pressure difference r pore-throat radius || parallel ⊥ series T temperature

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Section: Theoretical Methodology 21 Effective Thermal Conductivity mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigating the effective thermal conductivity of moist fibrous fabric based on Parallel-Series model: a consideration of material’s swelling effect

Zhu

2020

Mater. Res. Express

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“…The research on the heat transfer mechanism of thermal storage has made some achievements in theoretical model construction, experimental characteristic analysis, and thermal-fluid-solid three-field coupling numerical simulation. Jia et al [20] proposed a rock-soil thermal conductivity model based on the serial-parallel thermal resistance method, which was verified by the thermal conductivity of 74 rock samples. The results show that the model can accurately predict the thermal conductivity of rocksoil media with different components and different water content under the condition of low permeability and high permeability.…”

Section: Introductionmentioning

confidence: 99%

Construction and application analysis of thermal conductivity model of deep thermal storage pore structure

et al. 2023

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In the process of geothermal energy exploitation and utilization, effective heat extraction, natural recovery and other key issues are affected and restricted by the thermal conductivity process of geothermal reservoirs, and the relevant thermal conductivity model research is not very comprehensive at present. In this paper, the deep heat storage in pore structure is divided into development zone, wave zone and original zone according to their thermal conductivity characteristics. Based on the Representative Elementary Volume description analysis method, the thermal conductivity analysis model of pore structure of deep heat storage is established, including simplified thermal conductivity model and fine thermal conductivity model. Taking granite as an example, numerical calculation was carried out to analyze the effects of porosity, impurity content, water content and channel composition coefficient on heat storage and thermal conductivity. The model established in this paper lays a foundation for controlling thermal storage and thermal conductivity mechanism, accurately analyzing thermal conductivity characteristics, reserve estimation and mining dynamic changes.

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“…The factors affecting DBGHE performance-such as the sizes and thermo-physical properties of outer and inner pipes, the DBGHE flow rate and inlet temperature, the thermal physical properties of strata, and the geothermal gradient-have been studied in many references [2][3][4][5][6]. It is difficult to investigate DBGHEs by means of experiments or commercial numerical simulation software due to their depth of 2000-3000 m. Thus, most scholars modeled the heat transfer through the DBGHEs and the rocks and soil by adopting some methods to simplify heat transfer processes.…”

Section: Introductionmentioning

confidence: 99%

Effects of Boundary Conditions on Performance Prediction of Deep-Buried Ground Heat Exchangers for Geothermal Energy Utilization

Qin

Zhang

et al. 2023

Energies

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An accurate prediction for deep-buried ground heat exchangers (DBGHEs) is the premise for efficient utilization of geothermal energy. Due to the complexity of the geological composition spanning thousands of meters, the configuration of boundary conditions plays a critical role in evaluating DBGHE thermal performance. This paper proposed a three-dimensional model of full-scale DBGHE involving both conductive and convective heat transfer in aquifuge and aquifer layers. The constant inlet temperature and constant heating power boundaries in the DBGHE domain, and the surface–bottom temperature and heat flux boundaries in the rock-soil domain were examined. It was found that the differences in the performance prediction caused by different DBGHE boundary conditions were closely related to the system’s operating time. The relative differences in heat extraction amount and average borehole temperature of 2000 m DBGHE caused by the two inlet boundaries on the 30th day were, respectively, 19.5% and 18.3%, while these differences on the 120th day were decreased to 8.4% and 9.9%, respectively. It was found that the constant inlet temperature boundary was more appropriate than the constant heating power condition for estimating aquifer effects on the performance of DBGHE. For the rock-soil domain, the results showed that the heat extraction amount of DBGHE under the heat flux boundary was 12.6%–13.6% higher than that under the surface–bottom temperature boundary. Particularly, when considering the velocity change of groundwater in the aquifer, the relative difference in heat extraction amount increments caused by the two types of rock-soil boundaries can reach 26.6% on the 120th day. It was also found that the thermal influence radius at the end of a heating season was hardly affected by either the DBGHE inlet or rock-soil domain boundary conditions.

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Series-parallel resistance method based thermal conductivity model for rock-soil with low or high porosity

Cited by 22 publications

References 27 publications

Investigating the effective thermal conductivity of moist fibrous fabric based on Parallel-Series model: a consideration of material’s swelling effect

Investigating the effective thermal conductivity of moist fibrous fabric based on Parallel-Series model: a consideration of material’s swelling effect

Construction and application analysis of thermal conductivity model of deep thermal storage pore structure

Effects of Boundary Conditions on Performance Prediction of Deep-Buried Ground Heat Exchangers for Geothermal Energy Utilization

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