scholarly journals Few-Layer Graphene-Based Nanofluids with Enhanced Thermal Conductivity

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1258 ◽  
Author(s):  
Samah Hamze ◽  
Nawal Berrada ◽  
David Cabaleiro ◽  
Alexandre Desforges ◽  
Jaafar Ghanbaja ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Gum Arabic ◽  
Step Method ◽  
Conductivity Enhancement ◽  
Layer Graphene ◽  
Commercial Mixture ◽  
Complete Study ◽  
Wire Method ◽  
Enhancing Heat Transfer ◽  
Few Layer Graphene

High-quality graphene is an especially promising carbon nanomaterial for developing nanofluids for enhancing heat transfer in fluid circulation systems. We report a complete study on few layer graphene (FLG) based nanofluids, including FLG synthesis, FLG-based nanofluid preparation, and their thermal conductivity. The FLG sample is synthesized by an original mechanical exfoliation method. The morphological and structural characterization are investigated by both scanning and transmission electron microscopy and Raman spectroscopy. The chosen two-step method involves the use of thee nonionic surfactants (Triton X-100, Pluronic® P123, and Gum Arabic), a commercial mixture of water and propylene glycol and a mass content in FLG from 0.05 to 0.5%. The thermal conductivity measurements of the three FLG-based nanofluid series are carried out in the temperature range 283.15–323.15 K by the transient hot-wire method. From a modeling analysis of the nanofluid thermal conductivity behavior, it is finally shown that synergetic effects of FLG nanosheet size and thermal resistance at the FLG interface both have significant impact on the evidenced thermal conductivity enhancement.

Thermal Conductivity Enhancement of Binary Nanoemulsions (O/S)

2010 ◽  
Author(s):  
Hea Youn Sul ◽  
Jung-Yeul Jung ◽  
Yong Tae Kang
Keyword(s):  
Thermal Conductivity ◽  
Binary Solution ◽  
Gum Arabic ◽  
Strong Electrolyte ◽  
Scattering Method ◽  
Step Method ◽  
Conductivity Enhancement ◽  
Dynamic Light Scattering Method ◽  
Libr Solution ◽  
Wire Method

Binary nanoemulsions, nano-sized oil-droplet suspensions in binary solution (H2O/LiBr), are developed to enhance the heat and mass transfer performance of absorption refrigeration systems. In this study, a novel four-step method is proposed to prepare the stable oil-in-binary solution (O/S) emulsion. To stabilize the nanoemulsions in a strong electrolyte, a polymeric stabilizer (Gum Arabic) is used as a steric stabilizer. The droplet size and the thermal conductivity of binary nanoemulsions are measured by the dynamic light scattering method and the transient hot-wire method, respectively. It is concluded that the ratio of 2:1 (oil:surfactant) is the best condition for distribution stability. It is also found that the measured thermal conductivity of the oil-in-water nanoemulsion enhances up to 6.4% at 0.1 vol% of oil, and the binary nanoemulsion enhances up to 3.6% at 1.0 vol% of oil in 30 wt% H2O/LiBr compared with the estimated one from the Maxwell’s model. This result is compared with electric conductivity of LiBr solution and it is found both conductivities have similar trend. It is finally proposed that the thermal conductivity of the binary nanoemulsion could be enhanced by adding nano-sized droplets of n-decane oil, which has a lower thermal conductivity than that of the base fluid.

Thermal Conductivity Reduction in Few-Layer Graphene

2011 ◽  
Author(s):  
Dhruv Singh ◽  
Jayathi Y. Murthy ◽  
Timothy S. Fisher
Keyword(s):  
Thermal Conductivity ◽  
Weak Coupling ◽  
Phonon Scattering ◽  
Single Layer ◽  
Acoustic Mode ◽  
Single Layer Graphene ◽  
Boltzmann Transport ◽  
Layer Graphene ◽  
Out Of Plane ◽  
Few Layer Graphene

Using the linearized Boltzmann transport equation and perturbation theory, we analyze the reduction in the intrinsic thermal conductivity of few-layer graphene sheets accounting for all possible three-phonon scattering events. Even with weak coupling between layers, a significant reduction in the thermal conductivity of the out-of-plane acoustic modes is apparent. The main effect of this weak coupling is to open many new three-phonon scattering channels that are otherwise absent in graphene. The highly restrictive selection rule that leads to a high thermal conductivity of ZA phonons in single-layer graphene is only weakly broken with the addition of multiple layers, and ZA phonons still dominate thermal conductivity. We also find that the decrease in thermal conductivity is mainly caused by decreased contributions of the higher-order overtones of the fundamental out-of-plane acoustic mode. Moreover, the extent of reduction is largest when going from single to bilayer graphene and saturates for four layers. The results compare remarkably well over the entire temperature range with measurements of of graphene and graphite.

Thermal-Conductivity Enhancement of Microfluids With Ni3(μ3-ppza)4Cl2 Metal String Complex Particles

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Baghir A. Suleimanov ◽  
Hakim F. Abbasov ◽  
Fuad F. Valiyev ◽  
Rayyat H. Ismayilov ◽  
Shie-Ming Peng
Keyword(s):  
Thermal Conductivity ◽  
Thermal Conductivity Enhancement ◽  
Water Molecules ◽  
Glycerol Solution ◽  
Transient Hot Wire ◽  
Colloidal Structure ◽  
Conductivity Enhancement ◽  
Water Glycerol ◽  
Wire Method ◽  
Particle Assemblies

The thermal conductivity of microfluids comprising Ni3(μ3-ppza)4Cl2 metal string complex (MSC) microparticles in an aqueous glycerol solution was investigated using the transient hot-wire method. A comparative analysis of the thermal-conductivity enhancements of microfluids and nanofluids revealed that the best results were achieved using microparticles of monocrystalline MSCs Ni3(μ3-ppza)4Cl2 as well as Ni5(μ5-pppmda)4Cl2 micro- and copper nanoparticles. Compared to the base fluid, the thermal-conductivity enhancements were 72% for Ni3–water–glycerol, 53% for Cu–water–glycerol, and 47% for Ni5–water–glycerol. It is shown that the high thermal-conductivity enhancement achieved with Ni3 microfluids is a result of higher stability in compare with nanofluid due to the lower density of the microparticles and the formation of particle assemblies. Therefore, the formation of hydrogen bonds between the MSC particles (through their organic fragments) and water molecules, takes place. Colloidal structure of Ni3-microfluids has a significant impact on their thermophysical properties.

scholarly journals High yield production and purification of few layer graphene by Gum Arabic assisted physical sonication

2013 ◽  
Vol 3 (1) ◽  
Author(s):  
Victor Chabot ◽  
Brian Kim ◽  
Brent Sloper ◽  
Costas Tzoganakis ◽  
Aiping Yu
Keyword(s):  
Gum Arabic ◽  
High Yield ◽  
Layer Graphene ◽  
Yield Production ◽  
Few Layer Graphene ◽  
High Yield Production

Thermal Transport Measurements of Bilayer and Few-Layer Graphene Supported on Silicon Dioxide

2011 ◽  
Author(s):  
Mir Mohammad Sadeghi ◽  
Li Shi
Keyword(s):  
Thermal Conductivity ◽  
Silicon Dioxide ◽  
Thermal Conductance ◽  
Layer Graphene ◽  
Scattering Effects ◽  
Before And After ◽  
Linear Rise ◽  
Opposite Behavior ◽  
Few Layer Graphene ◽  
Sio2 Support

The thermal conductivity of bilayer graphene (BLG) and few-layer graphene (FLG) samples supported on a silicon dioxide (SiO2) bridge has been measured in the temperature range between 80 K and 375 K. In the experiments, resistance heater and thermometer lines at the two ends of the bridge were used to implement steady-state thermal conductance measurements of the sample before and after the graphene on the bridge was etched away. The obtained thermal conductivity of the supported graphene increases and the temperature for the peak thermal conductivity decreases with increasing layer thickness. Compared to the reported thermal conductivity of suspended FLG samples, the opposite behavior observed here for the supported FLG reveals that interaction with the SiO2 support and also possibly polymer residue on top of the FLG sample suppresses the thermal conductivity of the supported FLG more than interlayer interaction within the FLG. The linear rise of thermal conductivity with layer number up to 8 layers suggests that the scattering effects due to substrate and polymer residue penetrates much more than 4 layers into a multilayer flake.

Thermal Conductivity Enhancement of Binary Nanoemulsion(O/S) for Absorption Application

2009 ◽  
Author(s):  
Hea Youn Sul ◽  
Changhwan Cho ◽  
Jung-Yeul Jung ◽  
Yong Tae Kang
Keyword(s):  
Thermal Conductivity ◽  
Droplet Size ◽  
Binary Solution ◽  
Gum Arabic ◽  
Thermal Conductivity Enhancement ◽  
Strong Electrolyte ◽  
Scattering Method ◽  
Sorbitan Monolaurate ◽  
Conductivity Enhancement ◽  
Dynamic Light Scattering Method

Binary nanoemulsions, oil-droplet suspensions in binary solution (H2O/LiBr), are developed to enhance the heat and mass transfer performance of absorption refrigeration cycles. This paper studies the formation and stability of n-decane in H2O/LiBr nanoemulsions produced by using polyoxyethylene lauryl ether and polyoxyethylene sorbitan monolaurate as surfactant. To stabilize the nanoemulsions in a strong electrolyte, polymeric stabilizer (gum Arabic) is used as a steric stabilizer. The droplet size and the thermal conductivity of binary nanoemulsions are measured by the dynamic light scattering method and the transient hot-wire method, respectively. It is found that the effective thermal conductivity of binary nanoemulsions (1.0 vol % of n-decane in 30 wt % H2O/LiBr) enhances up to 3.59% with the average droplet size of 44.3 nm. The stability has more significant effect on the thermal conductivity enhancement than the initial drop size.

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