scholarly journals Visualization of Carbon Nanotube Aggregates in Dilute Phase of a Fluidized Bed

2018 ◽  
Vol 7 (3.34) ◽  
pp. 534
Author(s):  
Sae Han Park ◽  
Sung Won Kim
Keyword(s):  
Carbon Nanotube ◽  
Bulk Density ◽  
Fluidized Bed ◽  
High Speed ◽  
Laser Sheet ◽  
Scale Up ◽  
Average Diameter ◽  
Aggregation Behavior ◽  
Aggregation Process ◽  
Size And Shape

Background/Objectives: Fluidization characteristics and aggregation behavior of carbon nanotube (CNT) particles have been determined in the freeboard of a bubbling fluidized for the design and scale-up of the process.Methods/Statistical analysis: The aggregation behavior of the CNT particles was observed in a gas solid fluidized bed (0.15 m i.d. X 2.6 m high) using laser sheet technique for their visualization. A high speed camera was installed at the height of 0.67, 1.05 and 1.50 m above the gas distributor to observe the CNT aggregates behavior and determine their size and shape. The Image J was applied to process the obtained images.Findings: Effect of height in the reactor on aggregation of CNT particles have been determined. The axial local bulk density distribution is almost similar with a general bubbling fluidized bed such as Geldart A or Geldar B particles, which shows typically a dense bed at the bottom of the reactor and a decrease of the local bulk density with increasing height. The Feret and Heywood diameters of the aggregates are larger than the average diameter of the CNT particles, indicating that the CNT particles form the aggregates by physical entanglements and van der Waals force in the dilute phase of fluidized bed. A possible mechanism of aggregates formation was proposed based on the variation of size and shape of CNT aggregation with the height. The aggregation process in dilute phase is attributed largely to nanotubes stripping off the surface of CNT particles in addition to the inter-particle aggregation. The aggregation process affects the decrease of aspect ratio and the increase of solidity of aggregates with increasing the height.Improvements/Applications: The obtained results on the CNT properties could be used for the design of cyclone and the modeling of heat transfer in the fluidized bed reactor.  

scholarly journals Effect of Particle Size on Carbon Nanotube Aggregates Behavior in Dilute Phase of a Fluidized Bed

Processes ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 121 ◽  
Author(s):  
Sung Kim
Keyword(s):  
Particle Size ◽  
Carbon Nanotube ◽  
Fluidized Bed ◽  
Laser Sheet ◽  
Scale Up ◽  
Experimental Parameter ◽  
Aggregate Size ◽  
Chemical Vapor ◽  
Gas Velocity ◽  
Effect Of Particle Size

Fluidized bed reactors have been increasingly applied for mass production of Carbon Nanotube (CNT) using catalytic chemical vapor deposition technology. Effect of particle size (dp = 131 μm and 220 μm) on fluidization characteristics and aggregation behavior of the CNT particles have been determined in a fluidized bed for its design and scale-up. The CNT aggregation properties such as size and shape were measured in the dilute phase of a fluidized bed (0.15 m-ID × 2.6 m high) by the laser sheet technique for the visualization. Two CNT particle beds showed different tendency in variations of the aggregates factors with gas velocity due to differences in factors contributing to the aggregate formation. The CNT particles with a larger mean size presented as relatively larger in the aggregate size than the smaller CNT particles at given gas velocities. The aggregates from the large CNT particles showed a sharp increase in the aspect ratio and rapid decrease in the roundness and the solidity with gas velocity. A possible mechanism of aggregates formation was proposed based on the variations of aggregates properties with gas velocity. The obtained Heywood diameters of aggregates have been firstly correlated with the experimental parameter.

scholarly journals Scale-Up Preparation of Crocins I and II from Gardeniajasminoides by a Two-Step Chromatographic Approach and Their Inhibitory Activity Against ATP Citrate Lyase

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3137
Author(s):  
Shuguang Guan ◽  
Qiaoli Pu ◽  
Yinan Liu ◽  
Honghong Wu ◽  
Wenbo Yu ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
High Speed ◽  
Scale Up ◽  
Cost Effective ◽  
Atp Citrate Lyase ◽  
Gardenia Jasminoides ◽  
Citrate Lyase ◽  
Human Disorders ◽  
Ic50 Values ◽  
Counter Current

Crocins are highly valuable natural compounds for treating human disorders, and they are also high-end spices and colorants in the food industry. Due to the limitation of obtaining this type of highly polar compound, the commercial prices of crocins I and II are expensive. In this study, macroporous resin column chromatography combined with high-speed counter-current chromatography (HSCCC) was used to purify crocins I and II from natural sources. With only two chromatographic steps, both compounds were simultaneously isolated from the dry fruit of Gardenia jasminoides, which is a cheap herbal medicine distributed in a number of countries. In an effort to shorten the isolation time and reduce solvent usage, forward and reverse rotations were successively utilized in the HSCCC isolation procedure. Crocins I and II were simultaneously obtained from a herbal resource with high recoveries of 0.5% and 0.1%, respectively, and high purities of 98.7% and 99.1%, respectively, by HPLC analysis. The optimized preparation method was proven to be highly efficient, convenient, and cost-effective. Crocins I and II exhibited inhibitory activity against ATP citrate lyase, and their IC50 values were determined to be 36.3 ± 6.24 and 29.7 ± 7.41 μM, respectively.

Study on the Formaldehyde Adsorption Kinetics of Dry Waters

2014 ◽  
Vol 809-810 ◽  
pp. 907-911
Author(s):  
Jun Long Wang ◽  
Jie Hou ◽  
Ting Jiang ◽  
Yong Jun He ◽  
Yao Dong Liang
Keyword(s):  
Adsorption Kinetics ◽  
High Speed ◽  
Adsorption Process ◽  
Average Diameter ◽  
Adsorption Rate ◽  
Absorption Kinetics ◽  
Order Model ◽  
Pseudo Second Order ◽  
Kinetics Of ◽  
Formaldehyde Adsorption

Dry waters with an average diameter of 82 μm were prepared by a high speed mixed route. The formaldehyde absorption kinetics of dry waters was investigated by simulating indoor formaldehyde pollution in glass chamber. The results showed that pseudo-second order model could be used to simulate the adsorption process; the adsorption rate was highest in the initial 60 minutes; when the adsorption lasted for 180 minutes, the adsorption reached equilibrium.

Transient Computational Fluid Dynamics/Discrete Element Method Simulation of Gas–Solid Flow in a Spouted Bed and Its Validation by High-Speed Imaging Experiment

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Ling Zhou ◽  
Lingjie Zhang ◽  
Weidong Shi ◽  
Ramesh Agarwal ◽  
Wei Li
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Discrete Element Method ◽  
Fluidized Bed ◽  
High Speed ◽  
Discrete Element ◽  
Bubble Shape ◽  
High Speed Imaging ◽  
Bed Height ◽  
Simulation Results

A coupled computational fluid dynamics (CFD)/discrete element method (DEM) is used to simulate the gas–solid two-phase flow in a laboratory-scale spouted fluidized bed. Transient experimental results in the spouted fluidized bed are obtained in a special test rig using the high-speed imaging technique. The computational domain of the quasi-three-dimensional (3D) spouted fluidized bed is simulated using the commercial CFD flow solver ANSYS-fluent. Hydrodynamic flow field is computed by solving the incompressible continuity and Navier–Stokes equations, while the motion of the solid particles is modeled by the Newtonian equations of motion. Thus, an Eulerian–Lagrangian approach is used to couple the hydrodynamics with the particle dynamics. The bed height, bubble shape, and static pressure are compared between the simulation and the experiment. At the initial stage of fluidization, the simulation results are in a very good agreement with the experimental results; the bed height and the bubble shape are almost identical. However, the bubble diameter and the height of the bed are slightly smaller than in the experimental measurements near the stage of bubble breakup. The simulation results with their experimental validation demonstrate that the CFD/DEM coupled method can be successfully used to simulate the transient gas–solid flow behavior in a fluidized bed which is not possible to simulate accurately using the granular approach of purely Euler simulation. This work should help in gaining deeper insight into the spouted fluidized bed behavior to determine best practices for further modeling and design of the industrial scale fluidized beds.

A Carbon Nanotubes Aggregation in Polymer Nanocomposites

2018 ◽  
Vol 935 ◽  
pp. 55-60 ◽  
Author(s):  
Louise B. Atlukhanova ◽  
George V. Kozlov
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Polymer Nanocomposites ◽  
Packing Density ◽  
Elasticity Modulus ◽  
Aggregation Process ◽  
Walk Dimension

Carbon nanotubes aggregation process in aggregates (bundles) has been studied. This process results in essential reduction of nanocomposites attainable elasticity modulus. The bundles packing density is defined by aggregation expectation time and corresponding carbon nanotube walk dimension up to sticking with a similar nanotube.

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