Influencing factors and measuring method of the heat conducting performance of UHMWPE single fiber

2017 ◽  
Vol 47 (8) ◽  
pp. 1908-1924 ◽  
Author(s):  
Dai Guoliang ◽  
Li Li ◽  
Xiao Hong ◽  
Zhai Maolin ◽  
Shi Meiwu
Keyword(s):  
Thermal Conductivity ◽  
Volume Fraction ◽  
Measuring Method ◽  
Theory Model ◽  
Single Fiber ◽  
Heat Conducting ◽  
Drawing Ratio ◽  
Equivalent Thermal Conductivity ◽  
Uhmwpe Fiber ◽  
The Difference

The fiber with higher thermal conductivity is rare and it is difficult to measure the thermal conductivity of a single fiber. In this paper, the composite samples of ultra-high molecular weight polyethylene (UHMWPE) fiber and epoxy resin were prepared in order to study the heat conducting properties of the UHMWPE fiber. The specific heat capacity and thermal conductivity of the samples were tested by the transient plane source method. Based on the serial–parallel equivalence theory model, the axial and radial thermal conductivities of the UHMWPE filament were calculated. Effects of the volume fraction of fiber, fineness and drawing ratio on thermal conductivity were explored. Also, the relationship between the structure and thermal conductive capacity was revealed. The results showed that the volume fraction of fibers should be large to obtain a relative accurate value. Moreover, the difference in fineness led to different thermal conductivity of the UHMWPE fiber, the cruder the fiber, the higher the thermal conductivity. Besides, as the drawing ratio increased, the crystallinity and orientation of the fibers also increased. Thus, the results were that the axial equivalent thermal conductivity of the filament was dramatically increased, while the radial equivalent thermal conductivity grew a little. The paper showed that UHMWPE fibers had much higher thermal conductivity than other fibers, and also provided a new method to get the thermal conductivity of UHMWPE single fiber.

Research of Thermal Conductivity and Tensile Strength of Carbon Black-Filled Nature Rubber

2009 ◽  
Vol 87-88 ◽  
pp. 200-205 ◽  
Author(s):  
Yan He ◽  
Zhong Yin ◽  
Lian Xiang Ma ◽  
Jun Ping Song
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Tensile Strength ◽  
Carbon Black ◽  
Volume Fraction ◽  
Carbon Black Particle ◽  
Black Particle ◽  
The Difference ◽  
Thermal Conductivities

Through measuring the thermal conductivities and tensile strength of nature rubbers filled with carbon black and comparing with each other, it is shown that the difference of carbon black particle size and the structure affects on the thermal conductivity and tensile strength of nature rubber. Thermal conductivities of carbon black-filled nature rubber are enhanced with the increase of volume fraction of filler; tensile strength of composite increases first and then decreases with the increase of carbon black volume fraction.

Enhanced thermal conductivity of epoxy/alumina composite through multiscale-disperse packing

2020 ◽  
Vol 55 (1) ◽  
pp. 17-25
Author(s):  
Hongkun Li ◽  
Weidong Zheng
Keyword(s):  
Thermal Conductivity ◽  
Volume Fraction ◽  
Mean Field ◽  
High Volume ◽  
Theory Model ◽  
Spherical Particles ◽  
Particle Sizes ◽  
Interfacial Resistance ◽  
Steady State Method ◽  
Cure Shrinkage

Inspired by the size of the voids in closest packing structures, we propose to use the combination of spherical particles with different size scales to increase the loading fraction of the fillers in epoxy-based composites. In this study, high loading up to 79 vol% has been achieved with multiscale particle sizes of spherical Al2O3 particles. The highest thermal conductivity of Al2O3-filled liquid epoxy measured by steady-state method is 6.7 W m−1 K−1 at 25°C, which is approximately 23 times higher than the neat epoxy (0.28 W m−1 K−1). Three models based on Maxwell mean-field scheme (MMF), differential effective medium (DEM) and percolation theory model (PTM) were utilized to assess our measured thermal conductivity data. We found that both DEM and PTM models could give good results at high volume fraction regime. We have also observed a considerable reduction (10–15%) of thermal conductivity in our Al2O3-filled cured epoxy samples. We attribute this reduction to the increasing of thermal interfacial resistance between Al2O3 particles and cured epoxy matrix, induced by cure shrinkage during the reaction. Our experiments have demonstrated that systems with multiscale particle sizes exhibit lower viscosity and can be filled with much higher fraction of fillers. We thus expect that higher thermal conductivity (probably >12 W m−1 K−1 based on DEM) can be achieved in future via filling higher thermal conductivity spherical fillers (e.g., AlN, SiC), increasing loading fraction by multiscale-disperse packing and reducing the effect from cure shrinkage.

Birefringence in the Boundary Layer of a Rarefied Heat Conducting Gas

1977 ◽  
Vol 32 (8) ◽  
pp. 801-804
Author(s):  
H. Vestner ◽  
J. J. M. Beenakker
Keyword(s):  
Differential Equation ◽  
Thermal Conductivity ◽  
Boundary Layer ◽  
Index Of Refraction ◽  
Heat Conducting ◽  
Parallel Plates ◽  
Tensor Polarization ◽  
Angular Momenta ◽  
Rank Tensor ◽  
The Difference

Abstract In a heat conducting diatomic gas enclosed between parallel plates, the second rank tensor polarization of the rotational angular momenta is non-zero only near the plates. Therefore the gas is birefringent only in a boundary layer which is a few mean free paths thick. The birefringence is calculated with the help of a differential equation and a boundary condition for the tensor polarization. The difference in the index of refraction for light polarized parallel, respectively perpendicular to the temperature gradient is evaluated for the gases N2 and CO with the information obtained from the field effects on viscosity and on thermal conductivity, and from thermomagnetic pressure difference measurements. The effect is estimated to be of measurable size.

Prediction of mechanical and thermal properties of particle reinforced hydrogel composites using the structural genome approach

2021 ◽  
pp. 2150004
Author(s):  
Lingzhi Han ◽  
Jincheng Lei ◽  
Zishun Liu ◽  
Heow Pueh Lee
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Volume Fraction ◽  
Mechanical And Thermal Properties ◽  
Equivalent Thermal Conductivity ◽  
Volume Fractions ◽  
Sequential Adsorption ◽  
Hydrogel Composites ◽  
Genome Model

In this paper, the structural genome approach is used for multiscale analyses to predict the mechanical and thermal properties of particle reinforced hydrogel composites. First, the structure genome model of particle reinforced hydrogel composites is created by the random sequential adsorption algorithm. Then the mechanical properties and equivalent thermal conductivity of hydrogel composites are numerically studied by the structural genome approach. The effects of particles with different volume fractions and material properties on their mechanical and thermal properties are investigated. From the simulation results, it can be found that within a certain range of volume fraction, the mechanical properties and equivalent thermal conductivity of hydrogel composites are positively correlated with the volume fractions of particles. We also find that with the increase of the mechanical properties and thermal conductivity of particles, the properties of hydrogel can be improved and eventually reach stabilization. The structural genome approach shows excellent efficiency in multiscale structure analysis. It is a convenient method for the simulation of complex soft material composites.

Effect of Percolation on Equivalent Thermal Conductivity of Insulating Layer in Insulated Metal Substrates

2003 ◽  
Author(s):  
Kenji Monden
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Volume Fraction ◽  
High Thermal Conductivity ◽  
Inorganic Filler ◽  
Interfacial Region ◽  
Equivalent Thermal Conductivity ◽  
Metal Base ◽  
Predictive Values ◽  
Insulating Layer

An insulated metal substrate (IMS) is a circuit board comprising an insulating layer on a metal base plate. The insulating layer is made from epoxy resin incorporating dense inorganic fillers with high thermal conductivity. Because the substrates have high thermal conductivity, they are used in applications where electric parts generate intense heat, such as inverters, amplifiers, motor drivers and so on. It is expected that the insulating layer has higher thermal conductivity as the use of an IMS is expanded. Therefore, the influence of percolation on the equivalent thermal conductivity of an insulating layer is considered. The effect of the volume fraction of inorganic filler on the equivalent thermal conductivity of insulating layer in IMS is experimentally investigated. The equivalent thermal conductivity of insulating layer as a function of volume fraction of filler is estimated by FEM and Monte Carlo technique together. The acquired value of percolation threshold volume fraction is the same grade as the previous reported value. Based on these experimental and numerical results, an effective thermal conductivity of a filler which contains surrounding interfacial region is evaluated. The effective thermal conductivity of an irregular filler is presumed smaller than that of a spherical filler. It is noted that the control of filler size and shape is important for the formation of high thermal conductivity of an insulating layer. In addition, an improved equation for the equivalent thermal conductivity of insulating layer in IMS is proposed. The predictive values from the equation for insulating layer in an improved IMS agree with experimental results.

Nanofluids as a Coolant in Functional Units’ Coolers of Automotive Equipment

2021 ◽  
Vol 3 (44) ◽  
pp. 137-141
Author(s):  
Ekaterina P. Parlyuk ◽  
Keyword(s):  
Thermal Conductivity ◽  
Ethylene Glycol ◽  
Copper Nanoparticles ◽  
Volume Fraction ◽  
Research Purpose ◽  
Heat Conducting ◽  
Main Function ◽  
Metal Consumption ◽  
Heat Carriers ◽  
Base Liquid

One of the most important elements of the cooling system of any automotive internal combustion engine is a coolant. Most often, water and a mixture of water with antifreeze are used as a coolant. Its main function is to transfer heat or to cool the engine. Nanofluids are promising heat carriers, with the help of which it is possible to reduce the metal consumption of aggregates, increase safety in emergency transient modes accompanied by boiling. (Research purpose) The research purpose is studying the possibilities, features and prospects of using innovative heat carriers as coolants of automotive equipment, which will allow overcoming the inefficiency of water and ethylene glycol mixtures, which consists in low thermal conductivity. (Materials and methods) Nanofluids consisting of a base liquid and nanoparticles of a highly heat-conducting material were proposed as innovative heat carriers. Their use in transport power plant coolers will reduce their volume and weight. Mixing of ethylene glycol and copper nanoparticles is effective, in such cases it is important to investigate the effect of the volume fraction of copper nanoparticles and the base liquid on thermal characteristics or to reduce the size of the radiator. Copper nanoparticles have better thermal conductivity than other nanoparticles (for example, aluminum oxide). (Results and discussion) It has been proved that the use of nanofluids in heating and ventilation systems can give a significant increase in heat transfer. At present the science of nanofluids is in its initial stage, for the development of this direction it is necessary to conduct comprehensive experimental studies of their chemical and physical properties, theoretical analysis, and compilation of general calculated correlations. (Conclusions) It was revealed that nanofluids can be effectively used as heat carriers of transport engines, with their use the metal consumption of coolers is reduced, the safety of units in emergency modes, including those accompanied by boiling, is increased.

Equivalent Thermal Conductivity of Insulating Layer in Insulated Metal Substrates

2006 ◽  
Vol 45 ◽  
pp. 2664-2669 ◽  
Author(s):  
Kenji Monden
Keyword(s):  
Thermal Conductivity ◽  
Volume Fraction ◽  
Base Plate ◽  
Circuit Board ◽  
Equivalent Thermal Conductivity ◽  
Metal Base ◽  
Predictive Values ◽  
Insulating Layer ◽  
Ceramic Fillers ◽  
Intense Heat

An insulated metal substrate (IMS) is a circuit board comprising an insulating layer on a metal base plate. The insulating layer is made from epoxy resin incorporating dense ceramic fillers. The substrates are used in applications where electric parts generate intense heat. It is expected that the insulating layer has higher thermal conductivity as the use of an IMS is expanded. Therefore, the influence of percolation on the equivalent thermal conductivity (ETC) of an insulating layer is considered. The Effect of the volume fraction of ceramic filler on the ETC of insulating layer in IMS is investigated. The ETC as a function of volume fraction of filler is estimated. Based on these experimental and numerical results, an ETC of a filler is evaluated. The ETC of an irregular filler is presumed smaller than that of a spherical filler. It is thought that the control of filler size and shape is important for the formation of high thermal conductivity of an insulating layer. In addition, an improved equation for the ETC of IMS is proposed. The predictive values from the equation for an improved IMS agree with experimental results.

Basic Study on Effects of Water Content on Printing Paper on Equivalent Thermal Conductivity

2018 ◽  
Vol 2018 (1) ◽  
pp. 41-43
Author(s):  
Takashi Fukue ◽  
Hirotoshi Terao ◽  
Koichi Hirose ◽  
Tomoko Wauke ◽  
Hisashi Hoshino ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Water Content ◽  
Basic Study ◽  
Equivalent Thermal Conductivity ◽  
Printing Paper

A Study of Some Mechanical and Physical Properties for Palm Fiber/Polyester Composite

2020 ◽  
Vol 38 (3B) ◽  
pp. 104-114
Author(s):  
Samah M. Hussein
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Dielectric Constant ◽  
Date Palm ◽  
Volume Fraction ◽  
Unsaturated Polyester ◽  
Dielectric Strength ◽  
Palm Fiber ◽  
Mechanical And Physical Properties ◽  
Polyester Composite

This research has been done by reinforcing the matrix (unsaturated polyester) resin with natural material (date palm fiber (DPF)). The fibers were exposure to alkali treatment before reinforcement. The samples have been prepared by using hand lay-up technique with fiber volume fraction of (10%, 20% and 30%). After preparation of the mechanical and physical properties have been studied such as, compression, flexural, impact strength, thermal conductivity, Dielectric constant and dielectric strength. The polyester composite reinforced with date palm fiber at volume fraction (10% and 20%) has good mechanical properties rather than pure unsaturated polyester material, while the composite reinforced with 30% Vf present poor mechanical properties. Thermal conductivity results indicated insulator composite behavior. The effect of present fiber polar group induces of decreasing in dielectric strength, and increasing dielectric constant. The reinforcement composite 20% Vf showed the best results in mechanical, thermal and electrical properties.

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