scholarly journals Effective Heat Transfer Pathways of Thermally Conductive Networks Formed by One-Dimensional Carbon Materials with Different Sizes

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1661 ◽  
Author(s):  
Lee ◽  
Lee ◽  
Kim ◽  
Noda ◽  
Shim ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Polymer Matrix ◽  
Carbon Materials ◽  
Interfacial Resistance ◽  
Hybrid Films ◽  
Hybrid Filler ◽  
One Dimensional ◽  
Effective Heat ◽  
Thermally Conductive

We investigated the heat transfer behavior of thermally conductive networks with one-dimensional carbon materials to design effective heat transfer pathways for hybrid filler systems of polymer matrix composites. Nano-sized few-walled carbon nanotubes (FWCNTs) and micro-sized mesophase pitch-based carbon fibers (MPCFs) were used as the thermally conductive materials. The bulk density and thermal conductivity of the FWCNT films increased proportionally with the ultrasonication time due to the enhanced dispersibility of the FWCNTs in an ethanol solvent. The ultrasonication-induced densification of the FWCNT films led to the effective formation of filler-to-filler connections, resulting in improved thermal conductivity. The thermal conductivity of the FWCNT-MPCF hybrid films was proportional to the MPCF content (maximum thermal conductivity at an MPCF content of 60 wt %), indicating the synergistic effect on the thermal conductivity enhancement. Moreover, the MPCF-to-MPCF heat transfer pathways in the FWCNT-MPCF hybrid films were the most effective in achieving high thermal conductivity due to the smaller interfacial area and shorter heat transfer pathway of the MPCFs. The FWCNTs could act as thermal bridges between neighboring MPCFs for effective heat transfer. Furthermore, the incorporation of Ag nanoparticles of approximately 300 nm into the FWCNT-MPCF hybrid film dramatically enhanced the thermal conductivity, which was closely related to a decreased thermal interfacial resistance at the intersection points between the materials. Epoxy-based composites loaded with the FWCNTs, MPCFs, FWCNT-MPCF hybrids, and FWCNT-MPCF-Ag hybrid fillers were also fabricated. A similar trend in thermal conductivity was observed in the polymer matrix composite with carbon-based hybrid films.

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%.

Heat Transfer of Mineral-Filled Polypropylene Foams

2010 ◽  
Vol 297-301 ◽  
pp. 990-995 ◽  
Author(s):  
Marcelo Antunes ◽  
Vera Realinho ◽  
Antonio B. Martínez ◽  
E. Solórzano ◽  
Miguel A. Rodríguez-Pérez ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Relative Density ◽  
Magnesium Hydroxide ◽  
Expansion Ratio ◽  
Plane Source ◽  
Inorganic Particles ◽  
Transient Plane Source ◽  
Thermally Conductive ◽  
Transient Plane Source Method

The thermal conductivity of unfilled polypropylene foams produced using different foaming processes has previously been demonstrated to be mainly affected by the foam’s bulk density [1]. The influence of adding inorganic particles is now studied, with the thermal conductivity of the mineral-filled PP foams being determined using the Transient Plane Source Method (TPS). To this end, two different fillers were used. The incorporation of high amounts (50 and 70 wt.%) of magnesium hydroxide resulted in considerably higher thermally conductive foamed materials, with interesting thermal anisotropies being observed for the higher expansion ratio foams. On the contrary, adding montmorillonite (MMT) nanoparticles did not considerably alter the thermal conductivity of the foams, their value being mainly affected by the relative density.

scholarly journals Synergistic Effects of Various Ceramic Fillers on Thermally Conductive Polyimide Composite Films and Their Model Predictions

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 484 ◽  
Author(s):  
Heeseok Song ◽  
Byoung Kim ◽  
Yong Kim ◽  
Youn-Sang Bae ◽  
Jooheon Kim ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Hybrid System ◽  
Prediction Models ◽  
Synergistic Effects ◽  
Composite Films ◽  
Hybrid Filler ◽  
Model Predictions ◽  
Thermally Conductive ◽  
Ceramic Fillers ◽  
Polyimide Matrix

In this study, thermally conductive composite films were fabricated using an anisotropic boron nitride (BN) and hybrid filler system mixed with spherical aluminum nitride (AlN) or aluminum oxide (Al2O3) particles in a polyimide matrix. The hybrid system yielded a decrease in the through-plane thermal conductivity, however an increase in the in-plane thermal conductivity of the BN composite, resulting from the horizontal alignment and anisotropy of BN. The behavior of the in-plane thermal conductivity was theoretically treated using the Lewis–Nielsen and modified Lewis–Nielsen theoretical prediction models. A single-filler system using BN exhibited a relatively good fit with the theoretical model. Moreover, a hybrid system was developed based on two-population approaches, the additive and multiplicative. This development represented the first ever implementation of two different ceramic conducting fillers. The multiplicative-approach model yielded overestimated thermal conductivity values, whereas the additive approach exhibited better agreement for the prediction of the thermal conductivity of a binary-filler system.

Effective heat conductivity of Honeycomb (porous) composite panel

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Cletus Matthew Magoda ◽  
Jasson Gryzagoridis ◽  
Kant Kanyarusoke
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Composite Material ◽  
Thermal Properties ◽  
Heat Conductivity ◽  
Composite Panel ◽  
Porous Composite ◽  
Content Type ◽  
One Dimensional ◽  
Coefficient Of Thermal Conductivity

Purpose The purpose of this paper is to validate an assumption of what to use as an effective (steady state) heat transfer coefficient of thermal conductivity for the honeycomb core sandwiched by Fiberglass face sheets composite. A one-dimensional model based on Fourier law is developed. The results are validated experimentally. Design/methodology/approach The results were obtained from the one-dimensional mathematical model of an overall or effective heat conductivity of the Honeycomb composite panel. These results were validated experimentally by applying heat flux on the specimen under controlled environment. The surface temperatures at different voltages were recorded and analysed. The skin of the sandwich composite material used in the investigation was Fiberglass sheet with a thickness of 0.5 mm at the bottom and 1.0 mm at the top surface. Both skins have a stacking sequence of zero degrees. Due to the presence of air cells in the core (Honeycomb), the model considers the conduction, convection and radiation heat transfer, across the thickness of the panel, combined as an effective conduction mode, whose value may be predicted by using the coefficient of thermal conductivity of the air based on the average temperature difference between the two skins. The experimental results for the heat transfer through the thickness of the panel provide validation of this assumption/prediction. Both infrared thermography and conventional temperature measurement techniques (thermocouples) were used to collect the data. Findings The heat transfer experiment and mathematical modeling were conducted. The data obtained were analyzed, and it was found that the effective thermal conductivity was temperature-dependent as expected. The effective thermal conductivity of the honeycomb panel was close to that of air, and its value could be predicted if the panel surface temperatures were known. It was also found that as temperature raised the variation between experimental and predicted effective air conduction raised up. This is because there was an increase in molecular diffusion and vibration. Therefore, the convection heat transfer increased at high temperatures and the air became an insulator. Originality/value Honeycomb composite panels have excellent physical and thermal properties that influence their performance. This study provides an appropriate method in determining thermal conductivity, which is one of the critical thermal properties of porous composite material. This paper also gives useful and practical data to industries that use or manufacture honeycomb composite panels.

Quasi-Steady-State Temperature Distribution in Periodically Contacting Finite Regions

1981 ◽  
Vol 103 (4) ◽  
pp. 739-744 ◽  
Author(s):  
B. Vick ◽  
M. N. O¨zis¸ik
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Steady State ◽  
Temperature Distribution ◽  
Interface Temperature ◽  
Quasi Steady State ◽  
Exact Analytical Solutions ◽  
One Dimensional ◽  
Steady State Temperature ◽  
Regular Cycle

Heat transfer across two surfaces which make and break contact periodically according to a continuous regular cycle is investigated theoretically and exact analytical solutions are developed for the quasi-steady-state temperature distribution for a two-region, one-dimensional, periodically contacting model. The effects of the Biot number, the thermal conductivity and thermal diffusivity of the materials and the duration of contact and break periods on the interface temperature and the temperature distribution within the solids are illustrated with representative temperature charts.

Impact of Altering Aspect Ratio of the Loading Particles on a Suspension’s Thermal Conductivity

2008 ◽  
Author(s):  
A. S. Cherkasova ◽  
J. W. Shan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Silicon Carbide ◽  
Aspect Ratio ◽  
Effective Medium Theory ◽  
Detailed Comparison ◽  
Interfacial Resistance ◽  
Micro Particles ◽  
Particle Aspect Ratio

It has been recognized that heat-transfer fluids used to convey thermal energy produced by one device to another can exhibit significant increases in thermal conductivity with the addition of highly conductive particles. Suspensions of nano- and micro-particles have attracted the most recent interest because of their enhanced stability against sedimentation, reduction in potential for clogging a flow system, as well as the tantalizing possibility of unexpected enhancements in thermal conductivity that have been reported in some experiments. Among various suspensions, considerable attention has focused on those containing large-aspect-ratio particles, such as carbon nanotubes. Although recent experiments have demonstrated enormous heat-transfer enhancements in these fluids, such increases were reportedly not in agreement with existing macroscale theories [1–3]. In this research we report on an experimental study of the effects of particle aspect ratio on the effective thermal conductivity of micro- and nano-particle suspensions. The influence of particle aspect ratio on the thermal properties of suspensions was first studied in dispersions of micron-sized, silicon-carbide particles with varying aspect ratio. To carry out a detailed comparison with theoretical predictions, particle aspect ratio and size distributions were measured. It is shown that the conductivity of the silicon-carbide suspensions can be quantitatively predicted by an effective-medium theory (EMT), provided the volume-weighted aspect ratio of the particles is used. The particle-aspect-ratio effect was further studied in the suspensions of multi-walled carbon nanotubes. Experimental data on the thermal conductivity of nanotube suspensions could also be interpreted in terms of the aspect-ratio dependence predicted by EMT if the additional nanoscale effect of interfacial resistance was considered.

Heat-Transfer Stability of Porous Fibrous Composition under Different Condition

2014 ◽  
Vol 1004-1005 ◽  
pp. 557-561
Author(s):  
Yu Juan Wang ◽  
Hai Zhen Chen ◽  
Jin Mei Wang ◽  
Mei Zhen Wang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Process ◽  
Surface Condition ◽  
Transfer Model ◽  
Unsteady Heat Transfer ◽  
One Dimensional ◽  
The One ◽  
Thermal Difference ◽  
Key Parameter

In this paper, the influences of different conditions on heat-transfer stability of porous fibrous composition were analyzed by the one-dimensional unsteady heat transfer model. It was resulted that the surface condition of composition was key parameter for heat performance during different thermal process. Great humidity and thermal difference caused the heat transfer fluctuating of material covering, and then changed the thermal conductivity. For the insulation materials under low temperature, the heat performance was sharply fluctuated nearby 0°C.

Not Enough Precision to Accurately Measure the Effect of CNT Functionalization on the Thermal Conductivity of PDMS/CNT Composite Under Strain Using Stepped-Bar Apparatus

2015 ◽  
Author(s):  
Matthew I. Ralphs ◽  
Nicholas Roberts
Keyword(s):  
Thermal Conductivity ◽  
Polymer Matrix ◽  
Measurement Techniques ◽  
Conductivity Measurement ◽  
Hydroxyl Group ◽  
Mechanical And Thermal Properties ◽  
Conductive Composites ◽  
Aerospace Applications ◽  
The Matrix ◽  
Thermally Conductive

Carbon nanotubes (CNTs) exhibit extraordinary mechanical and thermal properties and as such have become the subject of large research interest. Furthermore, CNTs in a polymer matrix have been shown to significantly enhance the thermal conductivity of the polymer/CNT composite in some cases. A few areas of application for this work are thermal interface materials, thermally conductive composites used in aerospace applications, and polymer heat exchangers. In each of these applications the purpose of the polymer or epoxy is to take advantage of the mechanical properties or chemical inertness. The current issue with their adoption is still the poor thermal conductivity. One approach to overcoming this issue is to embed thermally conductive materials into the host material in low concentrations to enhance the effective thermal conductivity. There has been a significant amount of work in this area, but we are far from an understanding that allows us to design a nanocomposite that gives the desired thermal conductivity (specifically in the high thermal conductivity range). This work explores the role that chemical modification (functionalization) of the CNT can play in tailoring thermal transport properties of the composite under strain. It is expected that the functionalization process would have some effect on conduction between the CNT and the polymer matrix and therefore either increase or decrease the ability of the composite to transport thermal energy. This paper focuses on three different functionalizations of CNT and explores the thermal conductivity of a polymer/CNT composite that uses polydimethylsiloxane (PDMS) as the matrix. The three functionalizations of CNTs considered are that of unfunctionalized, functionalized with a carboxyl group (-COOH), and functionalized with a hydroxyl group (-OH). The CNTs used in this study are strictly multi-walled carbon nanobutes (MWCNTs) purified to 95%. The effect of these three functionalizations on the overall thermal conductivity of the composite is evaluated through experimental methods with a stepped bar apparatus at various levels of strain on the composite sample. Results show that, while functionalization of the CNT may affect the CNT/PDMS bond, the stepped bar apparatus does not provide enough precision on the level of strain placed on the sample for a comparison across functionalizations. Future work will try to elucidate both the effect of strain and functionalization using multiple thermal conductivity measurement techniques.

scholarly journals A Thermo-electric Apparatus for Thermal Diffusivity and Thermal Conductivity Measurements

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4238 ◽  
Author(s):  
Zhang ◽  
Lin ◽  
Tsai ◽  
Wu ◽  
Wu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Heat Source ◽  
Experimental Results ◽  
Measurement Device ◽  
Thermo Electric ◽  
One Dimensional ◽  
Transfer Measurement ◽  
Heat Transfer Measurement

In this study, a one-dimensional heat transfer measurement device is developed based on the mathematical theory of the Angstrom method. To conform to the mathematical assumption, it is required that the device precisely controls the heat source to generate sinusoidal temperature signal. A thermo-electric module is used as the heat source for the measurement platform. This module is connected to a computer for program control, such that the temperature can be controlled quickly, precisely, and dynamically. In this study, five common heat-conducting materials are tested to verify the proposed one-dimensional heat transfer measurement device. By substituting the experimental results into the mathematical model of the Angstrom method, the thermal diffusion and thermal conductivity of the test material is calculated. The experimental results are compared with the physical properties of the materials, and the accuracy error is extremely low. This study confirmed that the Angstrom method theory applied thermal diffusivity and thermal conductivity measurement, which can be realized by thermo-electric temperature control technology.

scholarly journals Thermal Conductance of Epoxy/Alumina Interfaces

2021 ◽  
Vol 2133 (1) ◽  
pp. 012002
Author(s):  
Wei Yang ◽  
Yun Chen ◽  
Yipeng Zhang ◽  
Yongsheng Fu ◽  
Kun Zheng ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Polymer Composites ◽  
Polymer Matrix ◽  
Time Domain ◽  
Conductive Polymer ◽  
Thermal Conductance ◽  
Interfacial Thermal Conductance ◽  
Piranha Solution ◽  
Conductive Polymer Composites ◽  
Thermally Conductive

Abstract The interfacial thermal conductance (ITC) between filler and polymer matrix is considered as one of the important factors that limits the thermal conductivity of thermally conductive polymer composites. The effect of two different surface treatments (piranha solution and plasma) on ITC of epoxy/alumina was investigated using Time-domain thermoreflectance method (TDTR). The TDTR results show that compared with non-treated samples, the ITC of samples treated by piranha solution and plasma increased 2.9 times and 3.4 times, respectively. This study provides guidance for improving the thermal conductivity of thermally conductive polymer composites.

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