Thermal Conductivity of Composites with Carbon Nanotubes: Theory and Experiment

2012 ◽  
Vol 1479 ◽  
pp. 101-106
Author(s):  
J. Ordonez-Miranda ◽  
C. Vales-Pinzon ◽  
J. J. Alvarado-Gil
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Theoretical Model ◽  
Size Effects ◽  
Polyester Resin ◽  
Thermal Design ◽  
Theoretical Predictions ◽  
Theory And Experiment ◽  
Composite Samples

ABSTRACTIn this work, the thermal conductivity of composites made up of carbon nanotubes embedded in a polyester resin is investigated by comparing experimental data with theoretical predictions. The composite samples were prepared with a random and aligned distribution of carbon nanotubes. Its thermal conductivity is then measured by using the photothermal radiometry technique. The obtained experimental data is accurately described by the proposed theoretical model, which takes into account the size effects of the nanotubes. It is expected that the obtained results can provide useful insights on the thermal design of composites based on carbon nanotubes.

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).

Thermal Conductivity of Individual Single-Wall Carbon Nanotubes

2006 ◽  
Vol 129 (6) ◽  
pp. 705-716 ◽  
Author(s):  
Jennifer R. Lukes ◽  
Hongliang Zhong
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Single Wall Carbon Nanotubes ◽  
Heat Current ◽  
Single Wall Carbon ◽  
Simulation Methodology

Despite the significant amount of research on carbon nanotubes, the thermal conductivity of individual single-wall carbon nanotubes has not been well established. To date only a few groups have reported experimental data for these molecules. Existing molecular dynamics simulation results range from several hundred to 6600 W∕m K and existing theoretical predictions range from several dozens to 9500 W∕m K. To clarify the several-order-of-magnitude discrepancy in the literature, this paper utilizes molecular dynamics simulation to systematically examine the thermal conductivity of several individual (10, 10) single-wall carbon nanotubes as a function of length, temperature, boundary conditions and molecular dynamics simulation methodology. Nanotube lengths ranging from 5 nm to 40 nm are investigated. The results indicate that thermal conductivity increases with nanotube length, varying from about 10 W∕m to 375 W∕m K depending on the various simulation conditions. Phonon decay times on the order of hundreds of fs are computed. These times increase linearly with length, indicating ballistic transport in the nanotubes. A simple estimate of speed of sound, which does not require involved calculation of dispersion relations, is presented based on the heat current autocorrelation decay. Agreement with the majority of theoretical/computational literature thermal conductivity data is achieved for the nanotube lengths treated here. Discrepancies in thermal conductivity magnitude with experimental data are primarily attributed to length effects, although simulation methodology, stress, and intermolecular potential may also play a role. Quantum correction of the calculated results reveals thermal conductivity temperature dependence in qualitative agreement with experimental data.

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.

REGULARITIES OF THE INFLUENCE OF THE TEMPERATURE REGIME OF POLYMER NANOCOMPOSITES PREPARATION ON THEIR DENSITY

2017 ◽  
Author(s):  
Nataliia Fialko ◽  
◽  
Roman Dinzhos ◽  
Viktor Prokopov ◽  
Julii Sherenkovskiy ◽  
...  
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Melting Temperature ◽  
Polymer Nanocomposites ◽  
Temperature Regime ◽  
Mass Fraction ◽  
Polymer Melt ◽  
Polypropylene Matrix

Experimental data on the study of the dependence of the density of nanocomposites with a polypropylene matrix filled with carbon nanotubes on the overheating of the polymer melt relative to its melting temperature are presented. The results are performed for nanocomposites obtained using a method based on mixing components in a polymer melt using a special disk extruder. The level of overheating of the melt varied in the range from 5K to 75 K for different values of the mass fraction of the filler from 0.3 to 10.0%. The dependences of the density of the studied composites on the level of overheating of the polymer melt have been determined. The presence of a correlation between this dependence and the nature of the corresponding change in the thermal conductivity of composites has been established.

Thermal Conductivity of Single-Wall Carbon Nanotubes

2004 ◽  
Author(s):  
Hongliang Zhong ◽  
Jennifer R. Lukes
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Dynamics Simulation ◽  
Tube Length ◽  
Single Wall Carbon Nanotubes ◽  
Single Wall Carbon ◽  
Simulation Methodology

Despite the significant amount of research on single-wall carbon nanotubes, their thermal conductivity has not been well established. To date only one experimental thermal conductivity measurement has been reported for these molecules around room temperature, with large uncertainty in the thermal conductivity values. Existing theoretical predictions based on molecular dynamics simulation range from several hundred to 6600 W/m-K. In an attempt to clarify the order-of magnitude discrepancy in the literature, this paper utilizes molecular dynamics simulation to systematically examine the thermal conductivity of several (10, 10) single-wall carbon nanotubes as a function of length, temperature, boundary conditions and molecular dynamics simulation methodology. The present results indicate that thermal conductivity ranges from about 30–300 W/m-K depending on the various simulation conditions. The results are unconverged and keep increasing at the longest tube length, 40 nm. Agreement with the majority of literature data is achieved for the tube lengths treated here. Discrepancies in thermal conductivity magnitude with experimental data are primarily attributed to length effects, although simulation methodology, stress, and intermolecular potential may also play a role. Quantum correction of the calculated results reveals thermal conductivity temperature dependence in qualitative agreement with experimental data.

Phonon Thermal Conductivity of Superlattice Nanowires for Thermoelectric Applications

2003 ◽  
Vol 793 ◽  
Author(s):  
C. Dames ◽  
M. S. Dresselhaus ◽  
G. Chen
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Size Effects ◽  
Three Dimensional ◽  
Small Diameter ◽  
Particle Model ◽  
Phonon Thermal Conductivity ◽  
Alloy Scattering ◽  
Classical Size ◽  
Good Agreement

ABSTRACTAn incoherent particle model has been developed to predict the phonon thermal conductivity of nanowires and superlattice nanowires. It is argued that the surface roughness of most real nanowires prevents the formation of idealized confined dispersion relations for typical temperatures and diameters. Instead, the three-dimensional bulk dispersion is used, thus addressing only classical size effects. Four adjustable parameters capture the effects of diameter, superlattice, Umklapp, impurity, and alloy scattering. Predictions are compared with experimental data for nanowires and superlattice nanowires down to 22 nm diameter and 20 K, and are in good agreement above ∼40 nm diameter. The analysis suggests that ideal low thermal conductivity nanowires for thermoelectric applications would have small-diameter, alternating alloy segments that are acoustically dissimilar but electrically similar.

BOUND STATE AND RADIATIVE CORRECTIONS TO HEAVY QUARK FRAGMENTATION FUNCTIONS

1995 ◽  
Vol 10 (13n14) ◽  
pp. 1019-1026
Author(s):  
M.A. GOMSHI NOBARY
Keyword(s):  
Experimental Data ◽  
Heavy Quark ◽  
Bound State ◽  
Radiative Corrections ◽  
Gluon Radiation ◽  
Initial State ◽  
Quark Fragmentation ◽  
Theoretical Predictions ◽  
Fragmentation Functions ◽  
Theory And Experiment

We comment on heavy quark fragmentation models motivated by QCD and study the influence of bound state and radiative corrections on heavy quark fragmentation emphasizing the comparison between the theoretical predictions and experimental data. It seems that meson constituents internal motion and initial state QCD gluon radiation may have a kinematical role in improving the agreement between theory and experiment. These effects are more striking in the case of charm fragmentation.

scholarly journals The Thermal Conductivity of Periodic Particulate Composites as Obtained from a Crystallographic Mode of Filler Packing

2018 ◽  
Vol 2 (4) ◽  
pp. 71
Author(s):  
John Venetis ◽  
Emilio Sideridis
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Thermomechanical Properties ◽  
Influential Factors ◽  
Particulate Composites ◽  
Closed Form Expression ◽  
Form Expression ◽  
Theoretical Predictions ◽  
Advanced Model ◽  
Theoretical Results

In this paper, an icosahedral non-body-centered model is presented to simulate the periodic structure of a general class of homogeneous particulate composites, by predicting the particle arrangement. This model yielded three different variations, which correspond to three different deterministic particle configurations. In addition, the concept of a boundary interphase between matrix and inclusions was taken into account. In this framework, the influence of particle vicinity on the thermomechanical properties of the overall material was examined in parallel with the concept of boundary interphase. The simultaneous consideration of these two basic influential factors constitutes the novelty of this work. Next, by the use of this advanced model, the authors derived a closed-form expression to estimate the thermal conductivity of this type of composite. To test the validity of the model, the theoretical predictions arising from the proposed formula were compared with experimental data found in the literature, together with theoretical results obtained from several accurate formulae derived from other workers, and an adequate accordance was observed.

Numerical Investigation into Thermal Behavior of Brushless Permanent Magnet Motors

2011 ◽  
Vol 199-200 ◽  
pp. 1518-1522
Author(s):  
Lung Ming Fu ◽  
Chiufeng Lin ◽  
Chin Lung Chang ◽  
Jenhao Chang ◽  
Chien Hsiung Tsai
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Boundary Conditions ◽  
Permanent Magnet ◽  
Thermal Design ◽  
External Boundary ◽  
Transfer Model ◽  
Permanent Magnet Motor ◽  
Equivalent Thermal Conductivity ◽  
Cfd Method

The performance of brushless permanent magnet motor for electric vehicle applications is simulated by commercial CFD codes Fluent 6.3. It is difficult to model motor winding area and to well pose the motor external boundary conditions for using CFD method. A possible approach to simplify the thermal resistance computation is to use an empirical equivalent thermal conductivity of the system winding impregnation and insulation. The empirical equivalent thermal conductivity is case sensitive and regressed in the experiment. The same is true for the boundary condition of motor. In this paper, we proposed a new model to compute equivalent thermal conductivity and overcome the above problem. This model takes advantage of the packing bed heat transfer model proposed by Zehner and Schlünder. Besides, the boundary conditions are also obtained by the numerical experiments. The validity of CFD method using in the present paper is validated utilizing the experimental data. The numerical data are concurred with the experimental data. As a result, the CFD method is shown to be a feasible method for modern thermal design for brushless permanent magnet motor.

The mobilities of ions in unlike gases

1958 ◽  
Vol 250 (982) ◽  
pp. 411-425 ◽  
Keyword(s):  
Experimental Data ◽  
High Temperatures ◽  
Classical Theory ◽  
Theoretical Description ◽  
Low Field ◽  
Theoretical Predictions ◽  
Repulsive Forces ◽  
Theory And Experiment ◽  
Field Strengths

The available experimental data on the mobilities at low field strengths of ions in unlike gases are analyzed on the basis of a simple theoretical description. Some of the earlier conclusions are modified and the current discrepancies between theory and experiment are emphasized. It is shown that most of the measurements can be explained by classical theory on the assumption that the interaction between an ion and a gas particle is due to the polarization of the gas particle, but that there appears to be a consistent discrepancy of about 8 % between theoretical predictions and the series of measurements by the Bristol group. For gases of low polarizability or at high temperatures, the contribution of the repulsive forces must be considered and the case of Li+ in He is investigated in detail, an interaction being derived from which the observed variation of mobility with temperature may be reproduced.

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