The effects of temperature, volume fraction and vibration time on the thermo-physical properties of a carbon nanotube suspension (carbon nanofluid)

2008 ◽  
Vol 19 (31) ◽  
pp. 315701 ◽  
Author(s):  
A Amrollahi ◽  
A A Hamidi ◽  
A M Rashidi
Keyword(s):  
Carbon Nanotube ◽  
Physical Properties ◽  
Volume Fraction ◽  
Effects Of Temperature ◽  
Vibration Time ◽  
Thermo Physical Properties

Heat Transfer and Crystallization Modeling during Compression Molding of Thermoplastic Composite Parts

2015 ◽  
Vol 651-653 ◽  
pp. 1507-1512 ◽  
Author(s):  
Jalal Faraj ◽  
Baptiste Pignon ◽  
Jean Luc Bailleul ◽  
Nicolas Boyard ◽  
Didier Delaunay ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Physical Properties ◽  
Volume Fraction ◽  
Thermoplastic Composite ◽  
Large Temperature ◽  
Process Conditions ◽  
Thermoplastic Resin ◽  
Whole Process ◽  
Low Viscosity ◽  
Thermo Physical Properties

We present in this paper, the coupling of heat transfer to the crystallization of composite in a closed mold. The composite is based on thermoplastic resin (low viscosity PA 66) with glass fiber (50% volume fraction). In order to realize this coupling, an accurate characterizationof thermo physical properties in process conditions, especially in the molten and solid state is needed. In addition, theidentification of the parameters of crystallization kinetics is required. Therefore, we present the methods that were used to study the thermo physical properties as the thermal conductivity, heat capacity and the specific volume. Moreover, the kinetic of crystallization was estimated over a large temperature range by using Flash DSC and classical DSC. In order to validate the measurements, the whole process was modeled by finite elements. The model includes the resolution of the strong coupling between the heat transfer and crystallization. Finally, the experimental and numerical results were compared.

Thermo-Physical Properties of Copper Matrix Composites Reinforced with 3D-SiC Network

2010 ◽  
Vol 150-151 ◽  
pp. 144-149
Author(s):  
Hong Wei Xing ◽  
Jin Song Zhang ◽  
Xiao Ming Cao
Keyword(s):  
Thermal Conductivity ◽  
Physical Properties ◽  
Room Temperature ◽  
Volume Fraction ◽  
Copper Matrix ◽  
High Thermal Stability ◽  
Matrix Composites ◽  
Copper Matrix Composites ◽  
Specific Heat Capacities ◽  
Thermo Physical Properties

Copper matrix composites reinforced with 3D-SiC network (15v% and 20v% SiC) were fabricated by squeezing copper alloy into 3D-SiC network preforms. The thermo-physical properties of the copper matrix composites were investigated. The specific heat capacities of the composites were about 0.39~0.50 J•g-1•K-1. The coefficients of thermal expansion (CTEs) of the composites were found to be lower than 6.9×10-6 -1 at Room Temperature. The composites exhibited high thermal stability for 3D-SiC network advent. The thermal conductivity of the composites was in the range of 50~80W•m−1•K−1. The thermo-physical properties of Cu matrix composites had a great relationship with the structures of 3D-SiC network preforms. The thermal conductivity of the composites decreased with an increase in the volume fraction of SiC or the structures of the limbs changing compacted, but the CTEs were not completely according this rule.

scholarly journals A review on determining the refractive index function, thermal accommodation coefficient and evaporation temperature of light-absorbing nanoparticles suspended in the gas phase using the laser-induced incandescence

2018 ◽  
Vol 7 (6) ◽  
pp. 583-604 ◽  
Author(s):  
Evgeny Valerievich Gurentsov
Keyword(s):  
Refractive Index ◽  
Physical Properties ◽  
Laser Heating ◽  
Volume Fraction ◽  
Accommodation Coefficient ◽  
Nanosecond Laser ◽  
Index Function ◽  
Evaporation Temperature ◽  
Laser Induced Incandescence ◽  
Thermo Physical Properties

AbstractIn this review, the possibility of using pulsed, nanosecond laser heating of nanoparticles (NPs) is demonstrated, in order to investigate their thermo-physical properties. This approach is possible because the laser heating produces high NP temperatures that facilitate the observation of their thermal radiation (incandescence). This incandescence depends on the thermo-physical properties of the NPs, such as heat capacity, density, particle size, volume fraction and the refractive index of the particle material, as well as on the heat-mass transfer between the NPs and the surrounding gas media. Thus, the incandescence signal carries information about these properties, which can be extracted by signal analyses. This pulsed laser heating approach is referred to as laser-induced incandescence. Here, we apply this approach to investigate the properties of carbon, metal and carbon-encapsulated Fe NPs. In this review, the recent results of the measurements of the NP refractive index function, thermal energy accommodation coefficient of the NP surface with bath gas molecules and the NP evaporation temperature obtained using laser-induced incandescence are presented and discussed.

Effect of geometrical and temperature-dependence parameters on forced convection of a nanofluid in a micro-channel heat sink

2016 ◽  
Vol 13 (5) ◽  
pp. 399-406 ◽  
Author(s):  
Rabah Nebbati ◽  
Mahfoud Kadja
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Physical Properties ◽  
Forced Convection ◽  
Heat Sink ◽  
Volume Fraction ◽  
Micro Channel ◽  
Temperature Dependent ◽  
Content Type ◽  
Thermo Physical Properties

Purpose The purpose of this study is the numerical prediction of the thermal and hydraulic characteristics (Nusselt number and shear stress) of a forced convection laminar flow through a rectangular micro-channel heat sink, using constant and temperature-dependent thermo-physical properties. The effects of the solids volume fraction and the size of the micro-channel on heat transfer enhancement have also been investigated. Design/methodology/approach The authors use the flow of a water-Al2O3 nanofluid and a single-phase approach. The equations are solved using the commercial code Fluent Version 6.3. This code uses the finite volume approach to solve the equations subject to the boundary conditions, which govern three-dimensional conjugate convection-conduction heat transfer model. The physical domain was meshed using the code GAMBIT. The mesh used is non-uniform and was obtained by sweeping in the Z direction an X-Y surface meshed with QUAD/pave type cells. Findings The results clearly show that the inclusion of nanoparticles produces a considerable increase in the heat transfer. Also, the temperature-dependent models present higher values of local and average Nusselt number than in the case of constant thermo-physical properties, and an increase in the channel dimensions leads to an important increase in heat transfer. Consequently, we ensure a better cooling of the base of the micro-channel heat sink. Research limitations/implications Because of the settling of nanoparticles, the research results may not be generalized to high values of solids volume fraction. Therefore, researchers are encouraged to find other techniques of cooling when the heat loads exceed values that cannot be dissipated using nanonofluids. Practical implications The paper includes implications for the miniaturization of electronic devices such as in microprocessors or those used in robotics and automotive industries, where continually increasing power densities are requiring more innovative techniques of heat dissipation from a small area and small coolant requirements. Originality/value This paper shows the implementation of variable property nanofluid models in CFD commercial codes.

Thermo-Physical Properties of Ti-Coated Diamond/Al Composites Prepared by Pressure Infiltration

2010 ◽  
Vol 654-656 ◽  
pp. 2572-2575 ◽  
Author(s):  
Yang Zhang ◽  
Xi Tao Wang ◽  
Sen Bao Jiang ◽  
Jian Hua Wu
Keyword(s):  
Physical Properties ◽  
Volume Fraction ◽  
Coefficient Of Thermal Expansion ◽  
Metal Layer ◽  
Interfacial Bonding ◽  
Molten Salt Method ◽  
Pressure Infiltration ◽  
Diamond Particles ◽  
Interfacial Characteristic ◽  
Thermo Physical Properties

Thermo-physical properties of diamond reinforced Al composites were investigated. Volume fraction of diamond particles was up to 55%. In order to improve the interfacial bonding between diamond and aluminum, diamond particles were pre-coated with titanium using molten salt method. XRD and SEM observation showed that the Ti coating on diamond consists of carbide layer and metal layer, which mainly depend on temperature and time. The influences of the Ti coating on interfacial characteristic and the thermo-physical properties of the composites were studied. The interfacial characterization and thermal diffusivity measurements indicated that Ti coated diamond was more favorable on interfacial bonding and thermal properties. Ti coating on diamond resulted in an increase of thermal conductivity of the composites, from 200 to 430 W/mK along with a coefficient of thermal expansion of 6.40 × 10-6/K.

A Study on Mixed Convection Flow in a Lid-Driven Cavity Filled With Micropolar Nanofluid by Considering Brownian Motion

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Amin Hadizade ◽  
Amin Haghighi Poshtiri
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Physical Properties ◽  
Newtonian Fluid ◽  
Volume Fraction ◽  
Bottom Wall ◽  
Fluid Viscosity ◽  
Driven Cavity ◽  
Micropolar Nanofluid ◽  
Thermo Physical Properties

The mixed convective heat transfer of a micropolar nanofluid in a square lid-driven cavity has been numerically studied. The lid is thermally insulated, the side walls are kept cold, and the bottom wall is kept hot with sinusoidally thermal boundary condition. The governing equations were solved by finite volume method using the SIMPLE algorithm. The effect of Grashof number (102–105), the volume fraction of nanoparticles (0.0–0.1), and micropolarity (0.0–2.0) has been investigated on the heat transfer of Al2O3–water nanofluid. Also, the variable model was used to calculate fluid viscosity and thermal conductivity coefficient of the nanofluid. The results showed that an increase in Grashof amplifies the buoyancy force and enhances the Nusselt number. Also, an increase in vortex viscosity at low Grashof numbers strengthens the forced convection and increases the Nusselt number over the bottom wall. However, at Gr = 105, the increase in vortex viscosity up to K = 1.0 leads to a decrease in the amount of heat transfer, but its further increase entails the increase in heat transfer. Although the addition of nanoparticles to the fluid improves heat transfer rate, the extent of improvement at nonzero K values is lower than that in the Newtonian fluid. The comparison of the average Nusselt number computed on the hot wall under two different states of temperature-depended thermo-physical properties and constant thermo-physical properties reveals that their difference is more significant for the Newtonian fluid especially at higher volume fraction.

Thermo-Physical Properties of SiCAl Composites with High Volume Fraction of Reinforcement Prepared by Combining Powder Injection Molding and Pressure Infiltration

2011 ◽  
Vol 239-242 ◽  
pp. 1832-1837
Author(s):  
Hao He ◽  
Yi Min Li
Keyword(s):  
Particle Size ◽  
Injection Molding ◽  
Physical Properties ◽  
Volume Fraction ◽  
High Volume ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Pressure Infiltration ◽  
Johnson Model ◽  
Thermo Physical Properties

SiC/Al composites with high reinforcement content were fabricated by pressure infiltration of aluminum alloy into porous SiC preform obtained by powder injection molding using a bimodal powder mixture. The influence of powder loading and particle size on the thermo-physical properties of the prepared composites was investigated. The results indicate that the thermal conductivities (TC) increases and coefficients of thermal expansion (CTE) decreases with increasing powder loading and particle size of the coarse powders in the bimodal powder system. The TCs are below the estimated value based on Hasselman-Johnson model, mainly due to the residual pores and the irregular particle shape. The CTEs of the composites increase with increasing temperature from 100°C to 400°C, and the increasing rates vary at different temperature ranges. Deep cooling in liquid nitrogen is effective to bring dislocations in the matrix and thus reduces the CTEs.

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