Measurements of the Intrinsic Thermal Conductivity of Individual Multi-Wall Carbon Nanotubes

2011 ◽  
Author(s):  
Juekuan Yang ◽  
Scott W. Waltermire ◽  
Yang Yang ◽  
Deyu Li ◽  
Yunfei Chen
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Heat Source ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Experimental Studies ◽  
Contact Thermal Resistance ◽  
Multi Wall Carbon Nanotubes ◽  
The Past ◽  
Thermal Conductivities

Thermal transport through carbon nanotubes (CNTs) attracted a lot of attention over the past decade. Several experimental studies have been carried out to determine the thermal conductivities of CNTs [1–3]. However, the measurements are based on an individual CNT sample between two suspended membranes and the results actually include both the intrinsic thermal resistance of the CNT and the contact thermal resistance between the CNT and the two suspended membranes that serve as a heat source and a heat sink. Hence, the effective thermal conductivity extracted from these measurements should be lower than the intrinsic thermal conductivities of the CNTs measured. To minimize the contact thermal resistance, electron beam induce deposition (EBID) of different metals has been used to increase the contact area between the CNT and the heat source and sink [3,4]. However, it is still not clear how effective this treatment is and to what level the effective thermal conductivity obtained after the EBID treatment reflects the intrinsic one.

Effective Thermal Conductivity of Composites with Contact Thermal Resistance between the Inclusions and the Matrix

2020 ◽  
Vol 40 (8) ◽  
pp. 622-627
Author(s):  
I. V. Lavrov ◽  
A. A. Kochetygov ◽  
V. V. Bardushkin ◽  
A. P. Sychev ◽  
V. B. Yakovlev
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Contact Thermal Resistance ◽  
The Matrix

scholarly journals Investigation of Effective Thermal Conductivity for Ordered and Randomly Packed Bed with Thermal Resistance Network Method

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1666 ◽  
Author(s):  
Jian Yang ◽  
Yingxue Hu ◽  
Qiuwang Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Packed Bed ◽  
Random Packing ◽  
Packing Factor ◽  
Resistance Network ◽  
Network Method ◽  
Thermal Conductivities

In the present paper, the effective thermal conductivities of Li4SiO4-packed beds with both ordered and random packing structures were investigated using thermal resistance network methods based on both an Ohm’s law model and a Kirchhoff’s law model. The calculation results were also validated and compared with the numerical and experimental results. Firstly, it is proved that the thermal resistance network method based on the Kirchhoff’s law model proposed in the present study is reliable and accurate for prediction of effective thermal conductivities in a Li4SiO4-packed bed, while the results calculated with the Ohm’s law model underestimate both ordered and random packings. Therefore, when establishing a thermal resistance network, the thermal resistances should be connected along the main heat transfer direction and other heat transfer directions as well in the packing unit. Otherwise, both the total heat flux and effective thermal conductivity in the packing unit will be underestimated. Secondly, it is found that the effect of the packing factor is remarkable. The effective thermal conductivity of a packed bed would increase as the packing factor increases. Compared with random packing at similar packing factor, the effective thermal conductivity of packed bed would be further improved with an ordered packing method.

Prediction of effective thermal conductivity of multicomponent tribocomposites taking into account contact thermal resistance between inclusions and matrix

2020 ◽  
pp. 36-40
Author(s):  
I.V. Lavrov ◽  
A.A. Kochetygov ◽  
V.V. Bardushkin ◽  
A.P. Syichev ◽  
V.B. Yakovlev
Keyword(s):  
Thermal Conductivity ◽  
Composite Material ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Field Approximation ◽  
Effective Field ◽  
Contact Thermal Resistance ◽  
Model Calculations ◽  
Spherical Inclusions ◽  
The Matrix

A method is proposed for predicting the effective thermal conductivity of a matrix composite with several types of spherical inclusions with contact thermal resistance at the boundary of the matrix and inclusions. The method is based on a generalized effective-field approximation for an inhomogeneous medium with inclusions with a shell. Model calculations were performed for a matrix tribocomposite with two types of inclusions. Keywords: effective thermal conductivity, contact thermal resistance, composite material, matrix, inclusion with a shell, Maxwell—Garnett approximation, generalized effective-field approximation. [email protected]

Experimental Study on Thermophysical Properties of Nanotubes and Nanofluids

2007 ◽  
Author(s):  
Xing Zhang ◽  
Motoo Fujii
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Experimental Study ◽  
Thermophysical Properties ◽  
Experimental Studies ◽  
Spherical Nanoparticles ◽  
Hot Wire ◽  
Transient Short Hot Wire ◽  
Different Diameters ◽  
Thermal Conductivities

This paper reviews the studies of the thermophysical properties of nanotubes and nanofluids and reports the experimental studies on the thermal conductivity of individual carbon nanotubes and nanofluids containing spherical and cylindrical nanoparticles. The thermal conductivity of a single carbon nanotube has been measured by a suspended sample-attached T-type nanosensor. The size effect of the different diameters on the thermal conductivity has been observed experimentally. The effective thermal conductivity and thermal diffusivity of Au/toluene, Al2O3/water, TiO2/water, CuO/water and carbon nanofibers (CNFs)/water nanofluids have been measured by using the transient short-hot-wire technique. The measured results demonstrate that the effective thermal conductivities of CNFs/water nanofluids are much greater than those of nanofluids containing spherical nanoparticles. However, the effective thermal conductivities do not show any anomalous enhancements and can be accurately predicted by the existing formulas.

Particle Aspect-Ratio and Agglomeration-State Effects on the Effective Thermal Conductivity of Aqueous Suspensions of Multiwalled Carbon Nanotubes

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Anna S. Cherkasova ◽  
Jerry W. Shan
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Effective Thermal Conductivity ◽  
Particle Aggregation ◽  
Multiwalled Carbon ◽  
Agglomeration State ◽  
Particle Aspect Ratio ◽  
Absorption Measurements ◽  
Thermal Conductivities

The effective thermal conductivities of aqueous nanofluids containing surfactant-stabilized multiwalled carbon nanotubes were measured and compared with the predictions of effective medium theory (Nan, C.-W., et al., 1997, “Effective Thermal Conductivity of Particulate Composites With Interfacial Thermal Resistance,” J. Appl. Phys., 81(10), pp. 6692–6699). Detailed characterization of nanotube morphology was carried out through electron microscopy, while the nanotube agglomeration state was monitored through optical microscopy and absorption measurements. An optimum surfactant-to-nanotube mass ratio was found for the particular surfactant, sodium dodecylbenzene sulfonate, which resulted in the greatest increase in thermal conductivity. Taking into consideration the volume-weighted aspect ratio of the nanotubes, the measured thermal conductivities of the suspensions were shown to be in good agreement with calculations for a reasonable choice of interfacial resistance on the particle/liquid interface. The effect of particle aspect ratio on the suspension’s thermal conductivity was further demonstrated and compared with theory by reducing the nanotube length through intense ultrasonication. The effect of particle aggregation on the thermal conductivity was also investigated by destabilizing previously stable suspensions with ethanol addition, which causes surfactant desorption and bundling of nanotubes. The measured thermal conductivities were correlated with absorption measurements and microscopic visualizations to show that particle aggregation decreases the thermal conductivity of the nanofluid by reducing the effective particle aspect ratio.

scholarly journals FUNDAMENTALLY NEW APPROACHES TO SOLVING THERMOPHYSICAL PROBLEMS IN THE FIELD OF NANOELECTRONICS

2021 ◽  
Author(s):  
Vladimir Khvesyuk ◽  
Aleksandr Barinov ◽  
B. Liu ◽  
W. Qiao
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Solid State ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Contact Thermal Resistance ◽  
New Approaches ◽  
Rough Boundaries

The paper discusses current problems related to the heat transfer in solid-state nanostructures: the influence of real rough boundaries on the effective thermal conductivity and contact thermal resistance

Contact Thermal Resistance Between Individual Multi-Wall Carbon Nanotubes

2011 ◽  
Author(s):  
Juekuan Yang ◽  
Scott W. Waltermire ◽  
Yang Yang ◽  
Deyu Li ◽  
Yunfei Chen
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Polymer Composites ◽  
Low Cost ◽  
Epoxy Composites ◽  
Materials Properties ◽  
Multi Wall Carbon Nanotubes ◽  
The Past ◽  
Volume Production ◽  
Positive Results

Carbon nanotubes (CNTs), because of their superior mechanical, electrical, and thermal properties and possible low-cost, large volume production, have been projected as promising nanostructure additives in polymer composites to achieve tunable and enhanced materials properties. Transport properties of CNT-polymer composites have been widely studied over the past decade and it is well-accepted that when the added CNTs exceed the percolation limit, the electrical conductivity of CNT-polymer composites can usually increase by several orders of magnitude. However, thermal conductivity measurements present mixed results and even for positive results, the enhancement is much lower than that expected from traditional theories. For example, Biercuk et al. [1] demonstrated that 1 wt% of single-wall CNTs (SWCNTs) in industrial epoxy could increase the thermal conductivity by 125% at room temperature, three-times higher than that from 1 wt% loading of carbon nanofibers. However, similar studies [2] showed that thermal conductivity only increased marginally for multi-wall CNT (MWCNT)-epoxy composites and more surprisingly, the thermal conductivity for SWCNT-epoxy composites was even lower than that of pure epoxy.

Influence of heat source size and film thickness on phonon transport in a two-dimensional thin film

2014 ◽  
Vol 39 (2) ◽  
Author(s):  
Haider Ali ◽  
Bekir S. Yilbas
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Heat Source ◽  
Film Thickness ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Phonon Transport ◽  
Source Size ◽  
Two Dimensional ◽  
Ballistic Phonons

Abstract.Phonon transport in a two-dimensional thin silicon film is considered and the effect of heat source size and the film thickness on the transport characteristics is examined. Frequency dependent Boltzmann equation is incorporated in the analysis to account for the contribution of the ballistic phonons to the energy transport. Equivalent equilibrium temperature is introduced to assess the thermal resistance during the phonon transport in the film. The numerical scheme with the appropriate boundary conditions is used to predict the transport properties, including the effective thermal conductivity, of the thin film. It is found that the heat source size and the film thickness influence the thermal resistance of the film almost equally. The ballistic phonons reduce the film thermal resistance while suppressing the effective thermal conductivity in the thin film.

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