EFFECTIVE THERMAL CONDUCTIVITY OF NANOFLUIDS CONTAINING CYLINDRICAL NANOPARTICLES

2007 ◽  
Vol 06 (01) ◽  
pp. 45-49 ◽  
Author(s):  
JAMSHID SABBAGHZADEH ◽  
SADOLLAH EBRAHIMI
Keyword(s):  
Thermal Conductivity ◽  
Theoretical Model ◽  
Effective Thermal Conductivity ◽  
Experimental Results ◽  
Cylindrical Shape ◽  
Nanoparticle Diameter ◽  
Conductivity Of Nanotubes

We present a theoretical model for explaining the enhancement in the effective thermal conductivity of nanotubes (cylindrical shape particles) for use in nanotube-in-fluid suspensions. Our theoretical model shows that the effective thermal conductivity is decreased with cylindrical nanoparticle diameter, which agrees with experimental results. We also show that with the decrease of nanotube diameter, the thermal conductivity increases if the thickness of nanolayers increases. We provide a good estimation for the nanolayer's thickness which plays an important role in increasing the thermal conductivity.

scholarly journals Investigation of thermal conductivity of single-wall carbon nanotubes

2011 ◽  
Vol 15 (2) ◽  
pp. 565-570 ◽  
Author(s):  
Mahmoud Jafari ◽  
Majid Vaezzadeh ◽  
Momhamad Mansouri ◽  
Abazar Hajnorouzi
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Theoretical Model ◽  
Potential Energy ◽  
Experimental Results ◽  
Single Wall Carbon Nanotubes ◽  
Lattice Vibrations ◽  
Single Wall Carbon ◽  
Thermal Potential ◽  
Conductivity Behavior

In this paper, the thermal conductivity of Single-wall carbon nanotubes (SWCNTs) is determined by lattice vibrations (phonons) and free elections. The thermal conductivity of SWCNTs is modeled up to 8-300 K and the observed deviations in K-T figures of SWCNTs are explained in terms of phonon vibrations models. An suitable theoretical model is shown for thermal conductivity behavior with respect to temperature and is generalized for experimental results. This model enables us to calculate thermal conductivity SWNTs and Thermal Potential Energy (TPE).

Porosity and Effective Thermal Conductivity of Wire Screens

1990 ◽  
Vol 112 (1) ◽  
pp. 5-9 ◽  
Author(s):  
Won Soon Chang
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Theoretical Model ◽  
Effective Thermal Conductivity ◽  
Present Model ◽  
Model Based ◽  
Wire Screen ◽  
Simple Theoretical Model ◽  
Parallel Conduction ◽  
The Wire

A simple theoretical model based on combined series and parallel conduction for the effective thermal conductivity of fluid-saturated screens has been developed. The present model has been compared with the existing correlations and experimental data available in literature, and it has been found that the model is effective in predicting thermal conductivity. The study also demonstrates that it is important to include the actual thickness of the wire screen in order to calculate the porosity accurately.

A theoretical model for the effective thermal conductivity of silica aerogel composites

2018 ◽  
Vol 128 ◽  
pp. 1634-1645 ◽  
Author(s):  
Yan-Jun Dai ◽  
Yu-Qing Tang ◽  
Wen-Zhen Fang ◽  
Hu Zhang ◽  
Wen-Quan Tao
Keyword(s):  
Thermal Conductivity ◽  
Theoretical Model ◽  
Effective Thermal Conductivity ◽  
Silica Aerogel

Thermal Conductivity Affected by Temperature and Particle Size in Al2O3-Water Nanofluids

2011 ◽  
Author(s):  
D. Kwek ◽  
A. Crivoi ◽  
Fei Duan
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Effective Thermal Conductivity ◽  
Experimental Results ◽  
Al2o3 Nanoparticles ◽  
Particle Sizes ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Nanoparticle Concentration ◽  
Wire Method

The effective thermal conductivity of Al2O3-water nanofluids has been measured using a transient hot wire method. Experimental results demonstrate that the thermal conductivity of Al2O3 nanofluids increases linearly with increasing nanoparticle concentration. Adding 5 vol % of Al2O3 nanoparticles in water increases the effective thermal conductivity of the nanofluids by 20%. Thermal conductivity of Al2O3 nanofluids increases with an increase of temperature. The enhancement is around 1.7% at 15 °C in comparison with around 16% at 55 °C in a 1 vol % nanofluid. The particle size is another important parameter for the effective thermal conductivity. The increase of thermal conductivity reduces from 30% to 10% as the particle sizes increase from 10 nm to 35 nm. The increase of the effective thermal conductivity starts as the particle size increases above 35 nm, reaching about 27.5% in the nanofluid with the particle size at 150 nm.

Comparison of Effective Thermal Conductivity of Hollow Fibers by Prediction Models and FE Method

2013 ◽  
Vol 440 ◽  
pp. 3-8
Author(s):  
Guo Cheng Zhu ◽  
Jiří Militký ◽  
Yan Wang ◽  
Juan Huang ◽  
Dana Kremenakova
Keyword(s):  
Thermal Conductivity ◽  
Theoretical Model ◽  
Effective Thermal Conductivity ◽  
Prediction Models ◽  
Heating Surface ◽  
Theoretical Models ◽  
Hollow Fibers ◽  
Fe Method ◽  
Ansys Simulation ◽  
Regular Structures

In order to evaluate the effective thermal conductivity (ETC) of hollow fibers, three theoretical models (the parallel/series model, quadrate model and cylindrical model) and finite element method carried out by ANSYS simulation were studied. The results showed that different theoretical models gave quite different effective thermal conductivities. The results from theoretical models and simulations were completely identical in the case when models had regular structures and the heating surface was the same kind of material. The ETC of hollow fibers from all of theoretical models and simulations decreased exponentially with the increase of air volume content. In addition, the ETC of hollow fibers from the first theoretical model were a bit higher than the results from simulation, whereas those from the second theoretical model were smaller than the results from simulation, and those from the third theoretical model were identical to the results from simulation.

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