Effective thermal conductivity in nanofluids of nonspherical particles with interfacial thermal resistance: Differential effective medium theory

2006 ◽  
Vol 100 (2) ◽  
pp. 024913 ◽  
Author(s):  
Xiao Feng Zhou ◽  
Lei Gao
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Effective Medium Theory ◽  
Effective Medium ◽  
Interfacial Thermal Resistance ◽  
Nonspherical Particles ◽  
Medium Theory

Particle Aspect-Ratio Effects on the Thermal Conductivity of Micro- and Nanoparticle Suspensions

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
Anna S. Cherkasova ◽  
Jerry W. Shan
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Aspect Ratio ◽  
Effective Thermal Conductivity ◽  
Effective Medium Theory ◽  
Effective Medium ◽  
Particulate Composites ◽  
Interfacial Thermal Resistance ◽  
Recent Experimental Data ◽  
Medium Theory

The influence of particle anisotropy on the effective thermal conductivity of a suspension is experimentally investigated. Suspensions of micron-sized, silicon-carbide particles with varying aspect-ratio distributions were prepared and measured. It is shown that the conductivity of the silicon-carbide suspensions can be quantitatively predicted by the effective medium theory of Nan et al. (1997, “Effective Thermal Conductivity of Particulate Composites With Interfacial Thermal Resistance,” J. Appl. Phys. 81(10), pp. 6692–6699), provided the volume-weighted aspect ratio of the particles is used. Recent experimental data on multiwalled-nanotube-in-oil suspensions by Yang et al. (2006, “Thermal and Rheological Properties of Carbon Nanotube-in-Oil Dispersions,” J. Appl. Phys., 99(11), 114307) are also analyzed and shown to be in at least qualitative agreement with the effective-medium-theory prediction that the thermal conductivity of suspensions is enhanced by large aspect-ratio particles.

scholarly journals Thermal conductivity of silicone elastomer with a porous alumina continuum

e-Polymers ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 845-853
Author(s):  
Qichao Song ◽  
Bo Wang ◽  
Zhiyu Han ◽  
Zhidong Han
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Medium Theory ◽  
Porous Alumina ◽  
Theoretical Models ◽  
Silicone Elastomer ◽  
Interfacial Thermal Resistance ◽  
X Ray Diffraction ◽  
Medium Theory ◽  
Gel Casting

Abstract In this paper, porous alumina continuum (PAC) was prepared with alumina powders (APs) by the gel-casting method and was applied to obtain silicone elastomer (SR) composites (PAC/SR) by the impregnating process. The structure was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influences of PAC on thermal conductivity and dielectric permittivity of PAC/SR composites were studied in comparison with AP/SR composites. When the alumina content was 14 vol%, the thermal conductivity of the PAC/SR composites reached 0.84 W·(m·K)−1, which was 3.1 times higher than that of the AP/SR composites. The thermal conductivity of PAC/SR and AP/SR was simulated by theoretical models, and the interfacial thermal resistance was calculated by effective medium theory, which indicated the advantages of PAC in enhancing the thermal conductivity of SR-based composites and the reduced interfacial thermal resistance between PAC and SR.

Effective Thermal Conductivity of Functionally Graded Particulate Nanocomposites With Interfacial Thermal Resistance

2008 ◽  
Vol 75 (5) ◽  
Author(s):  
H. M. Yin ◽  
G. H. Paulino ◽  
W. G. Buttlar ◽  
L. Z. Sun
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Functionally Graded ◽  
Interfacial Thermal Resistance ◽  
Conductivity Distribution ◽  
Consistent Model ◽  
The Matrix ◽  
Graded Material ◽  
Perfect Interface

By means of a fundamental solution for a single inhomogeneity embedded in a functionally graded material matrix, a self-consistent model is proposed to investigate the effective thermal conductivity distribution in a functionally graded particulate nanocomposite. The “Kapitza thermal resistance” along the interface between a particle and the matrix is simulated with a perfect interface but a lower thermal conductivity of the particle. The results indicate that the effective thermal conductivity distribution greatly depends on Kapitza thermal resistance, particle size, and degree of material gradient.

scholarly journals Effect of Alignment on Enhancement of Thermal Conductivity of Polyethylene–Graphene Nanocomposites and Comparison with Effective Medium Theory

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1291
Author(s):  
Fatema Tarannum ◽  
Rajmohan Muthaiah ◽  
Roshan Sameer Annam ◽  
Tingting Gu ◽  
Jivtesh Garg
Keyword(s):  
Thermal Conductivity ◽  
Thermal Management ◽  
Laser Scanning ◽  
Effective Medium Theory ◽  
Laser Scanning Confocal Microscopy ◽  
Effective Medium ◽  
Medium Theory ◽  
K Value ◽  
Graphene Nanocomposites ◽  
Scanning Confocal Microscopy

Thermal conductivity (k) of polymers is usually limited to low values of ~0.5 Wm−1K−1 in comparison to metals (>20 Wm−1K−1). The goal of this work is to enhance thermal conductivity (k) of polyethylene–graphene nanocomposites through simultaneous alignment of polyethylene (PE) lamellae and graphene nanoplatelets (GnP). Alignment is achieved through the application of strain. Measured values are compared with predictions from effective medium theory. A twin conical screw micro compounder is used to prepare polyethylene–graphene nanoplatelet (PE-GnP) composites. Enhancement in k value is studied for two different compositions with GnP content of 9 wt% and 13 wt% and for applied strains ranging from 0% to 300%. Aligned PE-GnP composites with 13 wt% GnP displays ~1000% enhancement in k at an applied strain of 300%, relative to k of pristine unstrained polymer. Laser Scanning Confocal Microscopy (LSCM) is used to quantitatively characterize the alignment of GnP flakes in strained composites; this measured orientation is used as an input for effective medium predictions. These results have important implications for thermal management applications.

On the Effective Thermal Conductivity of Nanofluids With Fractal Aggregation

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
C. G. Subramaniam
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Effective Medium Theory ◽  
Functionally Graded ◽  
Fractal Aggregates ◽  
Medium Theory ◽  
Analytical Approximations ◽  
Proposed Model ◽  
Dispersing Medium ◽  
Dilute Limit

A generalized effective medium theory (EMT) is proposed to account for the fractal structure of the dispersed phase in a dispersing medium under the dilute limit. The thermal conductivity of nanofluids with fractal aggregates is studied using the proposed model. Fractal aggregates are considered as functionally graded spherical inclusions and its effective thermal conductivity is derived as a function of its fractal dimension. The results are studied for self-consistency and accuracy within the limitations of the analytical approximations used.

Effect of Particle Size and Aggregation on Thermal Conductivity of Metal-Polymer Nanocomposite

2016 ◽  
Author(s):  
Xiangyu Li ◽  
Wonjun Park ◽  
Yong P. Chen ◽  
Xiulin Ruan
Keyword(s):  
Thermal Conductivity ◽  
Effective Medium Theory ◽  
Low Cost ◽  
Polymer Nanocomposite ◽  
Theoretical Models ◽  
Effective Medium ◽  
Metal Nanoparticle ◽  
Local Concentration ◽  
Medium Theory ◽  
Aggregation Effect

Metal nanoparticle has been a promising option for fillers in thermal interface materials due to its low cost and ease of fabrication. However, nanoparticle aggregation effect is not well understood because of its complexity. Theoretical models, like effective medium approximation model, barely cover aggregation effect. In this work, we have fabricated nickel-epoxy nanocomposites and observed higher thermal conductivity than effective medium theory predicts. Smaller particles are also found to show higher thermal conductivity, contrary to classical models indicate. A two-level EMA model is developed to account for aggregation effect and to explain the size-dependent enhancement of thermal conductivity by introducing local concentration in aggregation structures.

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