Heat conduction in double-walled carbon nanotubes with intertube additional carbon atoms

2015 ◽  
Vol 17 (25) ◽  
pp. 16476-16482 ◽  
Author(s):  
Liu Cui ◽  
Yanhui Feng ◽  
Peng Tan ◽  
Xinxin Zhang
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Heat Conduction ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Reduction Mechanisms ◽  
Double Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Theoretical insights into the heat transfer performance and its reduction mechanisms in double-walled carbon nanotubes with intertube additional carbon atoms.

Increasing heat transfer performance of thermoplastic polyurethane by constructing thermal conduction channels of ultra-thin boron nitride nanosheets and carbon nanotubes

2020 ◽  
Vol 44 (43) ◽  
pp. 18823-18830
Author(s):  
Yue Ruan ◽  
Nian Li ◽  
Cui Liu ◽  
Liqing Chen ◽  
Shudong Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Tensile Strength ◽  
Thermal Conduction ◽  
Heat Transfer Performance ◽  
Thermoplastic Polyurethane ◽  
Transfer Performance ◽  
Boron Nitride Nanosheets ◽  
Thermally Conductive

The TPU-based thermally conductive composite reaches a thermal conductivity of 1.35 W m−1 K−1 and increases the tensile strength by at least 300%.

Influence of Brazing on the Heat Transfer Performance of Fins in Radiators

2000 ◽  
Author(s):  
Bengt Sundén ◽  
Andreas Abdon ◽  
Daniel Eriksson
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Detrimental Effect ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Two Dimensional ◽  
Air Gaps ◽  
One Dimensional ◽  
Temperature Distributions ◽  
Braze Joint

Abstract The performance of a radiator copper fin is considered as the braze joint between the fin and the brass tube is not perfect. The influence of different thermophysical properties of the brazing materials, created intermetallic compounds and possible air gaps is considered. Numerical methods for both two-dimensional and one-dimensional calculations have been developed. The finite volume technique is applied and in the two-dimensional case, boundary fitted coordinates are used. Heat conduction in the fin and braze joint coupled with convective heat transfer in a gas stream is analysed. Results in terms of fin temperature distributions and fin efficiencies are provided. It is found that the detrimental effect of a poor braze joint is not as large as reported previously in the literature.

Heat Conduction Effect on Oscillating Heat Pipe Operation

2011 ◽  
Author(s):  
C. D. Smoot ◽  
H. B. Ma ◽  
C. Wilson ◽  
L. Greenberg
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Heat Pipe ◽  
Heat Transfer Performance ◽  
Block Design ◽  
Transfer Performance ◽  
Copper Block ◽  
Oscillating Heat Pipe ◽  
Continuous Block ◽  
Adiabatic Section

The effect of heat conduction through the adiabatic section on the oscillating motion and heat transfer performance in an oscillating heat pipe (OHP) was investigated experimentally. Two, closed loop, 6-turn OHPs were constructed; one with a separate copper block for the evaporator and condenser sections (split block design) and one using a single continuous copper block for the evaporator, adiabatic, and condenser sections (continuous block design). The results show that the presence of heat conduction directly from the evaporator wall to the adiabatic section and from the adiabatic section to the condenser of a heat pipe will reduce the oscillating amplitude of the evaporator, adiabatic, and condenser temperatures. It was also found that in addition to a higher level of temperature uniformity, the continuous block design results in better heat transfer performance than a heat pipe without conduction through the adiabatic section.

Heat Conduction Simulation in Double-Walled Carbon Nanotubes With Intertube Additional Atoms

2014 ◽  
Author(s):  
Peng Tan ◽  
Yanhui Feng ◽  
Liu Cui ◽  
Xinxin Zhang
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Heat Conduction ◽  
Cross Section ◽  
Phonon Scattering ◽  
Simulation Method ◽  
Local Deformation ◽  
Structural Deformation ◽  
Double Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Heat conduction of double-walled carbon nanotubes (DWCNTs) with intertube additional carbon atoms was investigated using molecular dynamics (MD) simulation method. The interaction between carbon atoms was modeled using the Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) Potential. The related phonon density of states (DOS) was analyzed to help explain the heat conduction mechanism. It is indicated that intertube additional atoms of DWCNT will weaken the heat conduction along the axis. The addition of intertube atoms, which are covalently bonded to the inner and outer tubes, leads to localized structural deformation, which acting as a phonon barrier for ballistic heat transport. In addition, the intertube atoms become the new centers of phonon scattering and reduce VDOS. The deformation is the primary reason for the reduction of thermal conductivity. With the increasing number of additional atoms, the thermal conductivity of DWCNTs with atoms added at the same cross section drops sharply than that added along the tube axis, because the former addition causes more serious local deformation. Under the situation of addition at the cross section, if the number of intertube atoms is beyond a critical value, the distribution of these atoms seems to have little influences on the heat conduction in the tube.

scholarly journals Constructal Optimization for Cooling a Non-Uniform Heat Generating Radial-Pattern Disc by Conduction

Entropy ◽  
2018 ◽  
Vol 20 (9) ◽  
pp. 685 ◽  
Author(s):  
Jiang You ◽  
Huijun Feng ◽  
Lingen Chen ◽  
Zhihui Xie
Keyword(s):  
Heat Transfer ◽  
Finite Element Method ◽  
Heat Conduction ◽  
Heat Transfer Performance ◽  
Variable Cross ◽  
Transfer Performance ◽  
Cross Sectional ◽  
Radial Pattern ◽  
Uniform Heat ◽  
Width Coefficient

A heat conduction model in a radial-pattern disc by considering non-uniform heat generation (NUHG) is established in this paper. A series of high conductivity channels (HCCs) are attached on the rim of the disc and extended to its center. Constructal optimizations of the discs with constant and variable cross-sectional HCCs are carried out, respectively, and their maximum temperature differences (MTDs) are minimized based on analytical method and finite element method. Besides, the influences of the NUHG coefficient, HCC number and width coefficient on the optimal results are studied. The results indicate that the deviation of the optimal constructs obtained from the analytical method and finite element method are comparatively slight. When the NUHG coefficient is equal to 10, the minimum MTD of the disc with 25 constant cross-sectional HCCs is specifically reduced by 48.8% compared to that with 10 HCCs. As a result, the heat conduction performance (HCP) of the disc can be efficiently improved by properly increasing the number of HCCs. The minimum MTD of the disc with variable cross-sectional HCC is decreased by 15.0% when the width coefficient is changed from 1 to 4. Therefore, the geometry of variable cross-sectional HCC can be applied in the constructal design of the disc to a better heat transfer performance. The constructal results obtained by investigating the non-uniform heat generating case in this paper can contribute to the design of practical electronic device to a better heat transfer performance.

Thermal Analysis in Phase Change Materials (PCMs) Embedded With Metal Foams

2010 ◽  
Author(s):  
Y. Tian ◽  
C. Y. Zhao
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Natural Convection ◽  
Heat Transfer Enhancement ◽  
Flow Resistance ◽  
Phase Change Materials ◽  
Heat Transfer Performance ◽  
Metal Foams ◽  
Transfer Performance ◽  
Transfer Enhancement

The heat transfer enhancement for phase change materials (PCMs) has received increasing attention nowadays, since most of PCMs have low thermal conductivities which prolong the charging and discharging processes. Metal foams, as a sort of novel material with high thermal conductivity, are believed to be a promising solution to enhance the heat transfer performance of PCMs for thermal energy storage systems. The effects of natural convection on heat transfer enhancement for PCMs embedded with metal foams are investigated in this paper. The numerical investigation is based on the two-equation non-equilibrium heat transfer model, where the coupled heat conduction and natural convection in PCMs are considered at phase transition and liquid zones. The numerical results are validated by experimental data. In order to investigate the effect of metal foams on heat transfer, two different cases are compared in this study, which are the Case A (PCMs embedded with metal foams) and the Case B (pure PCMs). At the solid zone, heat conduction plays a dominant part because of natural convection’s absence, thus metal foams achieve much higher heat conduction rate than pure PCMs, and this can be attributed to the high thermal conductivity of metal foams skeleton and the heat can be quickly transferred through the foam solid structure to the whole domain of PCMs. At the two-phase zone and liquid zone, natural convection takes place and becomes the dominant heat transfer mode, but metal foam structures suppress the natural convection inside the PCMs owing to big flow resistance in metal foams. In spite of this suppression caused by metal foams, the overall heat transfer performance of Case A is still superior to the counterpart of Case B (pure PCMs), implying the enhancement of heat conduction offsets or exceeds the natural convection loss. The results show that the heat transfer enhancement due to the natural convection in PCMs embedded with metal foams is not as strong as expected, since metal foams have big flow resistance and the natural convection is suppressed. It also shows that better heat transfer performance can be achieved by using the metal foams of smaller porosity and bigger pore density. Last but not least, a series of detailed velocity and temperature profiles are given through numerical solutions, in order to present a vivid evolution of flow field and temperature profiles in the whole melting process.

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