scholarly journals Thermal conductivity of unsaturated clay-rocks

2010 ◽  
Vol 14 (1) ◽  
pp. 91-98 ◽  
Author(s):  
D. Jougnot ◽  
A. Revil
Keyword(s):  
Thermal Conductivity ◽  
Porous Material ◽  
Solid Phase ◽  
Model Parameters ◽  
Electrical Parameters ◽  
New Model ◽  
Unsaturated Clay ◽  
Unsaturated Porous Material ◽  
Clay Rocks ◽  
Good Agreement

Abstract. The parameters used to describe the electrical conductivity of a porous material can be used to describe also its thermal conductivity. A new relationship is developed to connect the thermal conductivity of an unsaturated porous material to the thermal conductivity of the different phases of the composite, and two electrical parameters called the first and second Archie's exponents. A good agreement is obtained between the new model and thermal conductivity measurements performed using packs of glass beads and core samples of the Callovo-Oxfordian clay-rocks at different saturations of the water phase. We showed that the three model parameters optimised to fit the new model against experimental data (namely the thermal conductivity of the solid phase and the two Archie's exponents) are consistent with independent estimates. We also observed that the anisotropy of the effective thermal conductivity of the Callovo-Oxfordian clay-rock was mainly due to the anisotropy of the thermal conductivity of the solid phase.

scholarly journals Thermal conductivity of unsaturated clay-rocks

2008 ◽  
Vol 5 (4) ◽  
pp. 2409-2423 ◽  
Author(s):  
D. Jougnot ◽  
A. Revil
Keyword(s):  
Thermal Conductivity ◽  
Solid Phase ◽  
Water Phase ◽  
Porous Rocks ◽  
Formation Factor ◽  
Resistivity Tomography ◽  
Textural Parameter ◽  
Unsaturated Clay ◽  
Clay Rocks ◽  
Good Agreement

Abstract. The thermal conductivity of porous materials can be related to the electrical conductivity and therefore electrical resistivity tomography can be used to map the thermal conductivity of porous rocks. In this paper, a relationship is developed to connect the thermal conductivity of unsaturated clay-rocks to the thermal conductivity of the different phases of the porous composite, a textural parameter called the thermal formation factor, and the tortuosity of the water phase. The thermal formation factor is related to the electrical formation factor and to the first Archie's first exponent m. The tortuosity of the water phase is related to the second Archie's exponent n and to the relative saturation of the water phase. A very good agreement is obtained between the new model and thermal conductivity measurements of packs of glass beads and cores of the Callovo-Oxfordian argillite at different saturations of the water phase. Anisotropy of the effective thermal conductivity is mainly due to the anisotropy of the thermal conductivity of the solid phase.

scholarly journals Improved Mathematical Model of Polluted Insulators nonlinear behaviour Under AC Voltage Based on Experimental Tests

2018 ◽  
Author(s):  
MousalrezaFaramarzi Palangar ◽  
Mohammad Mirzaie
Keyword(s):  
Thermal Conductivity ◽  
Mathematical Model ◽  
Mathematical Models ◽  
Experimental Tests ◽  
The Other ◽  
Critical Voltage ◽  
Nonlinear Behaviour ◽  
New Model ◽  
The Relationship ◽  
Good Agreement

Abstract—In this paper, an improved mathematical model for flashover behavior of polluted insulators is proposed based on experimental tests. In order to determine the flashover model of polluted insulators, the relationship between conductivity and salinity of solution pollution layer of the insulator is measured. Then, the leakage of current amplitude of four common insulators versus axial, thermal conductivity and arc constants temperature was determined. The experimental tests show that top leakage distance (TLd) to bottom leakage distance (BLd) ratio of insulators has a significant effect on critical voltage and current. Therefore, critical voltage and current were modeled by TLd to BLd ratio Index (M). Also, salinity of solution pollution layer of the insulators has been applied to this model by resistance pollution parameter. On the other hand, arc constants of each insulator in new model have been identified based on experimental results. Finally, a mathematical model is intended for critical voltage against salinity of solution pollution layer of different insulators. This model depends on insulator profile. There is a good agreement between the experimental tests of pollution insulators obtained in the laboratory and values calculated from the mathematical models developed in the present study.

scholarly journals Improved Mathematical Model of Polluted Insulators nonlinear behaviour Under AC Voltage Based on Experimental Tests

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
MousalrezaFaramarzi Palangar ◽  
Mohammad Mirzaie
Keyword(s):  
Thermal Conductivity ◽  
Mathematical Model ◽  
Mathematical Models ◽  
Experimental Tests ◽  
The Other ◽  
Critical Voltage ◽  
Nonlinear Behaviour ◽  
New Model ◽  
The Relationship ◽  
Good Agreement

In this paper, an improved mathematical model for flashover behavior of polluted insulators is proposed based on experimental tests. In order to determine the flashover model of polluted insulators, the relationship between conductivity and salinity of solution pollution layer of the insulator is measured. Then, the leakage of current amplitude of four common insulators versus axial, thermal conductivity and arc constants temperature was determined. The experimental tests show that top leakage distance (TLd) to bottom leakage distance (BLd) ratio of insulators has a significant effect on critical voltage and current. Therefore, critical voltage and current were modeled by TLd to BLd ratio Index (M). Also, salinity of solution pollution layer of the insulators has been applied to this model by resistance pollution parameter. On the other hand, arc constants of each insulator in new model have been identified based on experimental results. Finally, a mathematical model is intended for critical voltage against salinity of solution pollution layer of different insulators. This model depends on insulator profile. There is a good agreement between the experimental tests of pollution insulators obtained in the laboratory and values calculated from the mathematical models developed in the present study.

Numerical Simulation on the Effective Thermal Conductivity of Porous Material

2012 ◽  
Vol 557-559 ◽  
pp. 2388-2395
Author(s):  
Shan Qi Liu ◽  
Yong Bing Li ◽  
Xu Yao Liu ◽  
Bo Jing Zhu ◽  
Hui Quan Tian ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Numerical Simulation ◽  
Porous Material ◽  
Effective Thermal Conductivity ◽  
Random Distribution ◽  
Simulation Method ◽  
Solid Skeleton ◽  
Material Models ◽  
Application Prospects ◽  
Good Agreement

The thermal conductivity of porous material is an important basic parameter, but it is not easy to study, due to the complexity of the structure of porous material. In the present work, we show a numerical simulation method to study the thermal conductivity of the porous material. We generate 200 material models with random distribution of solid skeleton and air for a fixed porosity, then we get the effective thermal conductivity of the porous material by Monte Carlo statistical analysis. The results are in good agreement with the previous empirical formula. The numerical results show that the effective thermal conductivity of porous material depends on the thermophysical properties of solid skeleton and air, the pore distribution and pore structure, the numerical error decreases with the increase in the number of grids, this finite element method can be used to estimate the effective thermal conductivity of composites and maybe has broad application prospects in terms of computing the effective thermal conductivity and other physical properties of composite material with known components.

A MODEL FOR PREDICTING THE EFFECTIVE THERMAL CONDUCTIVITY OF NANOPARTICLE-FLUID SUSPENSIONS

2006 ◽  
Vol 05 (01) ◽  
pp. 23-33 ◽  
Author(s):  
S. M. S. MURSHED ◽  
K. C. LEONG ◽  
C. YANG
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Body Centered Cubic ◽  
Geometrical Structures ◽  
New Model ◽  
Water Based ◽  
Classical Models ◽  
Theoretical Results ◽  
Enhanced Thermal Conductivity ◽  
Good Agreement

The uniformity and homogeneously dispersed nanoparticles in base fluids contribute to enhanced thermal conductivity of the mixture. By considering the uniformity and geometrical structures (e.g., body-centered cubic) of homogeneously dispersed nanoparticles in base fluids, a model for determining the effective thermal conductivity (ETC) of such nanoparticle-fluid suspensions, commonly known as nanofluids is proposed in this study. The theoretical results of the effective thermal conductivities of TiO 2/Deionized (DI) water and Al 2 O 3/DI water-based nanofluids are presented, and they are found to be in good agreement with our experimental results and also with those reported in the literature. The new model presented in this study shows a better prediction of the effective thermal conductivity of nanofluids compared to other classical models attributed to Maxwell, Hamilton–Crosser, and Bruggeman.

scholarly journals Improved Mathematical Model of Polluted Insulators nonlinear behaviour Under AC Voltage Based on Experimental Tests

2018 ◽  
Vol 1 (3) ◽  
Author(s):  
MousalrezaFaramarzi Palangar ◽  
Mohammad Mirzaie
Keyword(s):  
Thermal Conductivity ◽  
Mathematical Model ◽  
Mathematical Models ◽  
Experimental Tests ◽  
The Other ◽  
Critical Voltage ◽  
Nonlinear Behaviour ◽  
New Model ◽  
The Relationship ◽  
Good Agreement

In this paper, an improved mathematical model for flashover behavior of polluted insulators is proposed based on experimental tests. In order to determine the flashover model of polluted insulators, the relationship between conductivity and salinity of solution pollution layer of the insulator is measured. Then, the leakage of current amplitude of four common insulators versus axial, thermal conductivity and arc constants temperature was determined. The experimental tests show that top leakage distance (TLd) to bottom leakage distance (BLd) ratio of insulators has a significant effect on critical voltage and current. Therefore, critical voltage and current were modeled by TLd to BLd ratio Index (M). Also, salinity of solution pollution layer of the insulators has been applied to this model by resistance pollution parameter. On the other hand, arc constants of each insulator in new model have been identified based on experimental results. Finally, a mathematical model is intended for critical voltage against salinity of solution pollution layer of different insulators. This model depends on insulator profile. There is a good agreement between the experimental tests of pollution insulators obtained in the laboratory and values calculated from the mathematical models developed in the present study.

scholarly journals The Stationary Concentrated Vortex Model

Climate ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 39
Author(s):  
Oleg Onishchenko ◽  
Viktor Fedun ◽  
Wendell Horton ◽  
Oleg Pokhotelov ◽  
Natalia Astafieva ◽  
...  
Keyword(s):  
Vortex Structure ◽  
Radial Direction ◽  
Symmetry Axis ◽  
Outer Part ◽  
Vertical Direction ◽  
Axially Symmetric ◽  
New Model ◽  
Vortex Model ◽  
Axis Of Symmetry ◽  
Good Agreement

A new model of an axially-symmetric stationary concentrated vortex for an inviscid incompressible flow is presented as an exact solution of the Euler equations. In this new model, the vortex is exponentially localised, not only in the radial direction, but also in height. This new model of stationary concentrated vortex arises when the radial flow, which concentrates vorticity in a narrow column around the axis of symmetry, is balanced by vortex advection along the symmetry axis. Unlike previous models, vortex velocity, vorticity and pressure are characterised not only by a characteristic vortex radius, but also by a characteristic vortex height. The vortex structure in the radial direction has two distinct regions defined by the internal and external parts: in the inner part the vortex flow is directed upward, and in the outer part it is downward. The vortex structure in the vertical direction can be divided into the bottom and top regions. At the bottom of the vortex the flow is centripetal and at the top it is centrifugal. Furthermore, at the top of the vortex the previously ascending fluid starts to descend. It is shown that this new model of a vortex is in good agreement with the results of field observations of dust vortices in the Earth’s atmosphere.

Optimization of thermal conductivity in composites loaded with the solid-solid phase-change materials

2018 ◽  
Vol 25 (6) ◽  
pp. 1157-1165
Author(s):  
Taoufik Mnasri ◽  
Adel Abbessi ◽  
Rached Ben Younes ◽  
Atef Mazioud
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Phase Change Materials ◽  
Solid Phase ◽  
Spherical Inclusions ◽  
First Case ◽  
The Matrix ◽  
Composite Conductivity ◽  
First Time

AbstractThis work focuses on identifying the thermal conductivity of composites loaded with phase-change materials (PCMs). Three configurations are studied: (1) the PCMs are divided into identical spherical inclusions arranged in one plane, (2) the PCMs are inserted into the matrix as a plate on the level of the same plane of arrangement, and (3) the PCMs are divided into identical spherical inclusions arranged periodically in the whole matrix. The percentage PCM/matrix is fixed for all cases. A comparison among the various situations is made for the first time, thus providing a new idea on how to insert PCMs into composite matrices. The results show that the composite conductivity is the most important consideration in the first case, precisely when the arrangement plane is parallel with the flux and diagonal to the entry face. In the present work, we are interested in exploring the solid-solid PCMs. The PCM polyurethane and a wood matrix are particularly studied.

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