scholarly journals Experimental Investigation of Freezing and Melting Characteristics of Graphene-Based Phase Change Nanocomposite for Cold Thermal Energy Storage Applications

2019 ◽  
Vol 9 (6) ◽  
pp. 1099 ◽  
Author(s):  
Shaji Sidney ◽  
Mohan Dhasan ◽  
Selvam C. ◽  
Sivasankaran Harish
Keyword(s):  
Thermal Conductivity ◽  
Bath Temperature ◽  
Melting Behavior ◽  
Melting Rate ◽  
Graphene Nanoplatelets ◽  
Melting Time ◽  
Functionalized Graphene ◽  
Maximum Increase ◽  
Volume Percentage ◽  
Melting Characteristics

In the present work, the freezing and melting characteristics of water seeded with chemically functionalized graphene nanoplatelets in a vertical cylindrical capsule were experimentally studied. The volume percentage of functionalized graphene nanoplatelets varied from 0.1% to 0.5% with an interval of 0.1%. The stability of the synthesized samples was measured using zeta potential analyzer. The thermal conductivity of the nanocomposite samples was experimentally measured using the transient hot wire method. A ~24% (maximum) increase in the thermal conductivity was observed for the 0.5% volume percentage in the liquid state, while a ~53% enhancement was observed in the solid state. The freezing and melting behavior of water dispersed with graphene nanoplatelets was assessed using a cylindrical stainless steel capsule in a constant temperature bath. The bath temperatures considered for studying the freezing characteristics were −6 °C and −10 °C, while to study the melting characteristics the bath temperature was set as 31 °C and 36 °C. The freezing and melting time decreased for all the test conditions when the volume percentage of GnP increased. The freezing rate was enhanced by ~43% and ~32% for the bath temperatures of −6 °C and −10 °C, respectively, at 0.5 vol % of graphene loading. The melting rate was enhanced by ~42% and ~63% for the bath temperatures of 31 °C and 36 °C, respectively, at 0.5 vol % of graphene loading.

scholarly journals Experimental Investigation of Freezing and Melting Characteristics Of Graphene Based Phase Change Nanocomposite for Cold Thermal Energy Storage Applications

2019 ◽  
Author(s):  
Shaji Sidney ◽  
Mohan Lal D ◽  
Selvam C ◽  
Sivasankaran Harish
Keyword(s):  
Thermal Conductivity ◽  
Bath Temperature ◽  
Melting Rate ◽  
Melting Time ◽  
Functionalized Graphene ◽  
Maximum Enhancement ◽  
Volume Percentage ◽  
Melting Characteristics ◽  
Wire Method ◽  
The Stability

In the present work freezing and melting characteristics of water seeded with chemically functionalized graphene nano-platelets in a vertical cylindrical capsule was experimentally studied. The volume percentage of functionalized graphene nano-platelets was varied from 0.1% to 0.5% with an interval of 0.1%. The stability of the synthesised samples were carried out by zeta potential distribution. The thermal conductivity of the nanocomposite samples were experimentally measured using transient hot wire method. A maximum enhancement of ~24% in the thermal conductivity was observed for the 0.5% volume percentage in the liquid state while a ~53% enhancement in the solid state. Freezing and melting behaviour of water dispersed with graphene nanoplatelets were carried out using a cylindrical stainless steel capsule in a constant temperature bath. The bath temperatures considered for studying freezing characteristics were considered to be −6 °C and −10 °C, while to study the melting characteristics the bath temperature was set as 31 °C and 36 °C. The freezing and melting time decreased for all the test conditions when the volume percentage of GnP increased.  The freezing rate was enhanced by ~ 43% and ~32% for the bath temperatures of −6 °C and −10 °C respectively at 0.5 vol % of graphene loading. The melting rate was enhanced by ~42% and ~63% for the bath temperature of 31 °C and 36 °C respectively at 0.5 vol % of graphene loading.

scholarly journals Solidification of Graphene-Assisted Phase Change Nanocomposites inside a Sphere for Cold Storage Applications

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3473 ◽  
Author(s):  
Rajendran Prabakaran ◽  
Shaji Sidney ◽  
Dhasan Mohan Lal ◽  
C. Selvam ◽  
Sivasankaran Harish
Keyword(s):  
Phase Change ◽  
Volume Fraction ◽  
Bath Temperature ◽  
Graphene Nanoplatelets ◽  
Stable Phase ◽  
Maximum Increase ◽  
Host Matrix ◽  
Volume Percentage ◽  
Conductivity Enhancement ◽  
Newtonian Behavior

In this work, we experimentally investigated the solidification behavior of functionalized graphene-based phase change nanocomposites inside a sphere. The influence of graphene nanoplatelets on thermal transport and rheological characteristics of the such nanocomposites were also discussed. We adopted the covalent functionalization method to prepare highly stable phase change nanocomposites using commercially available phase change material (PCM) OM08 as the host matrix and graphene nanoplatelets (GnPs) with 0.1, 0.3, and 0.5 volume percentage as the nano inclusions. We report a maximum thermal conductivity enhancement of ~102 and ~46% with 0.5 vol% in the solid and liquid states, respectively. Rheological measurements show that the pure PCM shows Newtonian behavior, whereas the inclusion of GnPs leads to the transition to non-Newtonian behavior, especially at lower shear rates. Viscosity of the nanocomposite increases with an increase in the volume fraction of GnP. For 0.5 vol% of GnPs, maximum increase in viscosity was found to be ~37% at a shear rate of 1000 s−1. Time required for complete solidification decreases with the loading of GnPs. Maximum reduction in solidification time with 0.5 vol% of GnPs was ~40% for bath temperature of −10°C.

scholarly journals Numerical Simulation of the Melting Behavior of Steel Scrap in Hot Metal

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 678
Author(s):  
Nanyang Deng ◽  
Xiaobin Zhou ◽  
Moer Zhou ◽  
Shiheng Peng
Keyword(s):  
Carbon Concentration ◽  
Vertical Direction ◽  
Bath Temperature ◽  
Melting Behavior ◽  
Melting Rate ◽  
Middle Part ◽  
Steel Scrap ◽  
Low Carbon ◽  
Carbon Distribution ◽  
Hot Metal

The current study focuses on the melting behavior of a scrap bar with low carbon content in hot metal which contains high carbon concentration by applying experiments and mathematical modelings. The experiments suggest that higher temperature is favorable for the melting of the bar and the melting rate of the bar is initially high while decreased to a relative stable level after 90 s in the current conditions. It can be found from the mathematical results that the bar temperature is increased near to bath temperature in about 20 s after it was immersed into the bath, and the temperature in the axis of the bar is not distributed evenly during the temperature increase stage. Moreover, the mathematical results shows that a bath circulation flow would be formed in the bath under the effects of temperature and carbon distribution during the melting process. The bath flow near the melting interface would influence the carbon concentration of the molten phase, in turn, affects the melting rate of the bar in the vertical direction. Both the experimental and mathematical results show that the melting rate in the upper part, which is in the upstream of the bath flow, is higher than that of the middle part, followed by the down part of the bar in the downstream of the flow, in which the carbon concentration is much lower than that of the bath. At this period, the main factor that dominate the bar melting is not the temperature but the carbon distribution at the melting interface after the bar temperature is increased to the bath temperature.

scholarly journals Silane-functionalized graphene nanoplatelets for silicone rubber nanocomposites

2022 ◽  
Author(s):  
He Ren ◽  
Eunice Cunha ◽  
Zheling Li ◽  
Lei Wang ◽  
Ian A. Kinloch ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Young’S Modulus ◽  
Silicone Rubber ◽  
Young's Modulus ◽  
Theoretical Models ◽  
Graphene Nanoplatelets ◽  
Functionalized Graphene ◽  
Raman Mapping ◽  
Rubber Nanocomposites ◽  
Considerable Enhancement

AbstractSilane-functionalized graphene nanoplatelets (GNPs) were prepared using a newly developed approach based upon a simple two-step strategy. The effect of their dispersion and interfacial bonding on the mechanical properties and thermal conductivity of reinforced silicone rubber (SR) was investigated. It was found by Raman mapping that the silane-functionalized GNPs could be dispersed uniformly into the SR matrix, leading to an increase of up to 25% in Young’s modulus at only 2 parts per hundred rubber (phr) loading and a considerable enhancement of up to 150% in the thermal conductivity at 5-phr loading. Both the Young’s modulus and thermal conductivity experimental results were found to be in agreement with the values predicted using theoretical models. Graphical abstract

Electrocatalyst based on Ni-MOF intercalated with amino acid-functionalized graphene nanoplatelets for the determination of endocrine disruptor bisphenol A

2021 ◽  
Vol 1150 ◽  
pp. 338228
Author(s):  
P. Arul ◽  
Sheng-Tung Huang ◽  
N.S.K. Gowthaman ◽  
G. Mani ◽  
Nithiya Jeromiyas ◽  
...  
Keyword(s):  
Amino Acid ◽  
Bisphenol A ◽  
Endocrine Disruptor ◽  
Graphene Nanoplatelets ◽  
Functionalized Graphene

Investigation of friction and wear behavior of hydroxyl-functionalized graphene nanoplatelets filled elastomer nanocomposites

2021 ◽  
pp. 146442072110616
Author(s):  
Hasan Kasim ◽  
Adem Onat ◽  
Barış Engin ◽  
İsmail Saraç
Keyword(s):  
Wear Rate ◽  
Tribological Properties ◽  
Wear Behavior ◽  
Normal Load ◽  
Graphene Nanoplatelets ◽  
Rubber Matrix ◽  
High Wear Resistance ◽  
Homogeneous Distribution ◽  
Functionalized Graphene ◽  
Sealing Elements

The use of unfilled pure elastomer parts is limited in friction wheels, roller tires, sealing elements, and dynamic friction air suspension applications requiring high wear resistance. This study investigates the mechanical and tribological properties of new nanocomposites obtained by adding hydroxyl-functionalized graphene nanoplatelets at 1, 4, and 8 phr (parts per hundred rubber) ratios to the carbon black filled main rubber compound of sealing elements designed for axle hubs. The synergistic effect of nanofiller materials on the wear behavior of nanocomposites was tested with a block-on-ring wear tester under dry sliding conditions at 1000 rpm and 15 N normal load conditions. The worn surfaces were examined with scanning electron microscopy and circularly polarized light–differential interference contrast topology microscopy to reveal the wear mechanism. The addition of functionalized graphene nanoplatelets to the nanocomposite compound caused significant changes in tensile strength and elongation values by changing the cross-link density. The wear rate of nanocomposites prepared with graphene nanoplatelets at 1, 4, and 8 phr ratios was 11.15%, 25.24%, and 36.54% lower than the main rubber mixture used, respectively. While the hysteresis loss decreased by 14.83% at 1 phr, this value increased in other filler ratios. Significant differences in temperature change occurred as the amount of filler increased. After the test, the temperature values of nanocomposites with 1 and 4 phr filler ratios were between about 85–89°C, while it was measured as 99°C in nanocomposites with 8 phr filler ratios. It has been observed that the homogeneous distribution of two-dimensional carbon allotropes such as graphene nanoplatelet added to the rubber matrix at the optimum rate will improve tribological properties such as better surface lubrication, low wear rate, and low friction coefficient.

COMPUTATIONAL MODELING OF EPOXY-BASED HYBRID COMPOSITES REINFORCED WITH CARBON FIBERS AND FUNCTIONALIZED GRAPHENE NANOPLATELETS

2021 ◽  
Author(s):  
HASHIM AL MAHMUD ◽  
, MATTHEW RADUE ◽  
WILLIAM PISANI ◽  
GREGORY ODEGARD
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
Hybrid Composites ◽  
Graphene Nanoplatelets ◽  
Pristine Graphene ◽  
Functionalized Graphene ◽  
Functionalized Graphene Oxide ◽  
Aspect Ratios ◽  
The Impact ◽  
Nanoscale Level

The impact on the mechanical properties of unidirectional carbon fiber (CF)/epoxy composites reinforced with pristine graphene nanoplatelets (GNP), highly concentrated graphene oxide (GO), and Functionalized Graphene Oxide (FGO) are investigated in this study. The localized reinforcing effect of each of the graphene nanoplatelet types on the epoxy matrix is predicted at the nanoscale-level by molecular dynamics. The bulk-level mechanical properties of unidirectional CF/epoxy hybrid composites are predicted using micromechanics techniques considering the reinforcing function, content, and aspect ratios for each of the graphene nanoplatelets. In addition, the effect of nanoplatelets dispersion level is also investigated for the pristine graphene nanoplatelets considering a lower dispersion level with four layers of graphene nanoplatelets (4GNP). The results indicate that the shear and transverse properties are significantly affected by the nanoplatelet type, loading and aspect ratio. The results of this study can be used in the design of hybrid composites to tailor specific laminate properties by adjusting nanoplatelet parameters.

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