The Effective Thermal Conductivity of a Multi-Phase System

1998 ◽  
Vol 51 (2) ◽  
pp. 349-360 ◽  
Author(s):  
B. M. Suleiman ◽  
S.E. Gustafsson ◽  
E. Karawacki ◽  
R. Glamheden ◽  
U. Lindblom
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Phase System ◽  
Multi Phase

scholarly journals Estimation of Effective Thermal Conductivity of Two-Phase Material for Hollow Circular Model

2018 ◽  
Vol 172 ◽  
pp. 02004
Author(s):  
Prateek Kumar Sahu ◽  
Nisha Netam ◽  
Lal Chandra Shah
Keyword(s):  
Thermal Conductivity ◽  
Circular Cylinder ◽  
Effective Thermal Conductivity ◽  
Complex Structure ◽  
Fundamental Property ◽  
Percentage Error ◽  
Phase System ◽  
Two Phase ◽  
Hollow Circular Cylinder ◽  
Circular Model

Two-phase materials are commonly used in engineering application because of its various properties like strength, thermal conductivity, durability and toughness etc. Effective thermal conductivity (ETC) of two-phase material is the fundamental property to predict its thermal performance. Various geometry (spheres, cylinders, irregular particles) have been considered by researchers for calculating ETC of two-phase materials. Due to complex structure, hollow circular cylinder geometry is not reported yet. In this paper, two-dimensional periodic two-phase system, with hollow circular cylinder shape is considered for calculating ETC. In present work unit cell approach method is used to derive collocated parameters model for estimation of ETC. Hollow circular cylinder model with Ψ = 0.2 gives good result for estimating ETC with average percentage error of 6.46%.

An Analytical Modeling for Effective Thermal Conductivity of Multi-Phase Transversely Isotropic Fiberous Composites Using Generalized Self-Consistent Method

2012 ◽  
Vol 249-250 ◽  
pp. 904-909 ◽  
Author(s):  
Syed Aadil Hassan ◽  
Hassaan Ahmed ◽  
Asif Israr
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Composite System ◽  
Volume Fraction ◽  
Transversely Isotropic ◽  
Balance Principle ◽  
Isotropic Composite ◽  
Self Consistent ◽  
Consistent Method ◽  
Multi Phase

In this paper a theoretical relationship for the effective thermal conductivity of a multiphase transversely isotropic composite system is obtained. The Generalized Self-Consistent Method and simple energy balance principle is employed to derive a more appropriate model. In the derivation, it is assumed that the orientation of fiber within the transversely isotropic composite system is unidirectional and surrounded by two different phases of porous and matrix phase. A combined effect of these three different phases on the effective thermal conductivity of the composite system in transverse direction is studied. The effect of the interfacial contact conductance between the fibers and porous medium is also considered. Results of effective thermal conductivity are plotted against volume fraction and conductance which shows extremely good agreement.

REVIEW AND APPLICATIONS OF THERMAL CONDUCTIVITY MODELS TO ALUMINUM CELL SIDEWALL REFRACTORIES

2009 ◽  
Vol 23 (06n07) ◽  
pp. 790-795 ◽  
Author(s):  
YUHUA PAN ◽  
STEVEN WRIGHT ◽  
SHOUYI SUN
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Aluminum Electrolysis ◽  
Laser Flash ◽  
Modeling Methods ◽  
Electrolysis Cells ◽  
Model Predictions ◽  
One Step ◽  
Laser Flash Technique ◽  
Multi Phase

Silicon nitride bonded silicon carbide ( Si 3 N 4- SiC ) refractories are commonly used as the sidewall of aluminum electrolysis cells. They have to withstand an extremely corrosive molten electrolyte bath for long periods. The sidewall is normally protected with a layer of solidified electrolyte (called frozen ledge), which is sensitive to the thermal conductivity of the sidewall. In this work, through review of the literature on modeling methods for predicting the effective thermal conductivity of dense composites and porous materials, some selected methods were applied to calculate the effective thermal conductivity of Si 3 N 4- SiC refractories. The model predictions were compared with the thermal conductivity of a commercial Si 3 N 4- SiC refractory measured by using laser flash technique. The present study showed that, due to multi-phase nature and complex microstructure of Si 3 N 4- SiC refractories, most of the selected modeling methods individually do not give satisfactory predictions in one step. Recursive applications of one method or combinations of different methods are capable of giving satisfactory predictions.

scholarly journals The Emergent Behaviour of Thermal Networks and Its Impact on the Thermal Conductivity of Heterogeneous Materials and Systems

2020 ◽  
Vol 4 (1) ◽  
pp. 32
Author(s):  
Chris R. Bowen ◽  
Kevin Robinson ◽  
Jianhui Tian ◽  
Meijie Zhang ◽  
Vincent A. Coveney ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Granular Media ◽  
Mixing Rule ◽  
Two Phase ◽  
Model Mixing ◽  
Two Phases ◽  
The Individual ◽  
Variability Region ◽  
Multi Phase

The properties of thermal networks are examined to understand the effective thermal conductivity of heterogeneous two-phase composite materials and systems. At conditions of high contrast in thermal conductivity of the individual phases (k1 and k2), where k1 << k2 or k1 >> k2, the effective thermal conductivity of individual networks of the same composition was seen to be highly sensitive to the distribution of the phases and the presence of percolation paths across the network. However, when the contrast in thermal conductivities of the two phases was modest (k1/k2 ~ 10−2 to 102), the thermal networks were observed to exhibit an emergent response with a low variability in the effective thermal conductivity of mixtures of the same composition. A logarithmic mixing rule is presented to predict the network response in the low variability region. Excellent agreement between the model, mixing rule and experimental data is observed for a range two-phase porous and granular media. The modelling approach provides new insights into the design of multi-phase composites for thermal management applications and the interpretation or prediction of their heat transfer properties.

Estimation of the Temperature-Dependent Thermal Conductivity of Multi-Phase Materials

2011 ◽  
Vol 340 ◽  
pp. 34-39
Author(s):  
Hai Feng Zhang ◽  
Peng Xin Li ◽  
Li Qun He
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Numerical Method ◽  
Effective Thermal Conductivity ◽  
Percolation Theory ◽  
Mixed Model ◽  
Effective Medium Approximation ◽  
Temperature Dependent ◽  
Multi Phase ◽  
Temperature Dependent Thermal Conductivity

Two Models for Estimating the Effective Thermal Conductivity (kE) of Multi-Phase Materials Are Comparatively Investigated. the First Model Is the Effective Medium Approximation (EMA), which Is Based on the Extension of the Percolation Theory. the Second Is the Randomly Mixed Model (RMM), a Numerical Method in which All Components Are Seen as Cubech_cubecucube in Shape and Are Randomly Dispersed inside the Space. Two Models Can Be Directly Applied to Multi-Phase Media without Empirical Parameters. Compared with Experimental Data of Food Materials in the Literature, Two Models both Give Good Estimations of the Temperature-Dependent KE.

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