Nanoparticle fluidization and Geldart's classification

Wang, Xiao Shan; Rahman, Farhana; Rhodes, Martin

doi:10.1016/j.ces.2007.02.051

Cited by 70 publications

(33 citation statements)

References 23 publications

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“…They exhibit agglomerate particulate fluidization (APF) characteristics between 0 and 3.3 U mf (minimum fluidization velocity) and agglomerate bubbling fluidization (ABF) features beyond 3.3 U mf with high bed expansion (Coppey, 2013). This behaviour is characteristic of the fluidization of nanoparticle agglomerates (Zhu et al, 2005;Wang et al, 2007). It should favour excellent gassolid contact and then high conversion rate of the CVD precursors and also uniform deposition.…”

Section: Experimental Set-upmentioning

confidence: 99%

Decoration of Carbon Nanotubes by Semiconducting or Metallic Nanoparticles using Fluidized Bed Chemical Vapour Deposition

Lassègue

Coppey

Noé

et al. 2016

KONA

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Multi-Walled Carbon Nanotubes (MWCNTs) have promising properties that make them potentially useful in a wide variety of applications. The decoration of MWCNTs by metallic or semiconducting nanoparticles aims to intensify some of their properties, in particular thermal and electrical conductivity. Fluidized Bed Chemical Vapour Deposition (FBCVD) is an efficient process to uniformly coat powders by various materials. The coating by SnO 2 , Fe and Si nanoparticles of MWCNTs (Graphistrength ® ) tangled in balls of 360 microns in mean diameter using the FBCVD process has been studied. The influence of some deposition parameters with and without oxidative pre-treatment is analysed on the nucleation and growth of nanoparticles. The various results obtained indicate that the intrinsic surface reactivity of MWCNTs is high enough for CVD precursors involving the formation of highly reactive unsaturated species such as silylene SiH 2 formed from silane SiH 4 pyrolysis in the case of Si deposition. But it must be enhanced for less reactive CVD precursors such as tin tetrachloride SnCl 4 which needs the presence of oxygen-containing groups at the nanotube surface to allow Sn nucleation. So, provided the reactivity of the powder surface and that of the CVD precursors are well tuned, the FBCVD process can uniformly coat the outer surface of MWCNTs by metallic or semiconducting nanoparticles.

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Section: Experimental Set-upmentioning

confidence: 99%

Decoration of Carbon Nanotubes by Semiconducting or Metallic Nanoparticles using Fluidized Bed Chemical Vapour Deposition

Lassègue

Coppey

Noé

et al. 2016

KONA

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“…There was no bubble formation until the inlet superficial velocity was five times higher than the minimum fluidization velocity. This bubble less bed expansion behavior was also observed by (Wang X. et al, 2007). However, when the inlet velocity was further increased, the airflow tried to create flow channels in the expanded bed.…”

Section: Fluidization Regimesmentioning

confidence: 79%

“…Group-D particles give a slower bubble rise velocity than the gas velocity (Kunii & Levenspiel, 1991). (Wang X. et al, 2007) showed that Nano-sized particles possess both Group-A and Group-B behavior. Group-B bubbles, which are at the interface between dense phase and freeboard, affect bed collapse time (Pei et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Study of Fluidization Regimes using OpenFOAM Computational Fluid Dynamics

Welahettige

Lie

Vaagsaether

et al. 2017

Linköping Electronic Conference Proceedings

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The objective of this study was using computational fluid dynamics simulation with OpenFOAM to study the fluidization properties for four types of particles classified as Geldart A, B, C and D. Fluidization regimes were studied for particles with the same density but different diameters. The particle diameters were selected based on Geldart's classification of particles. The simulation results were validated against experimental data. Pressure gradient, flow regime change, bubble rise, bubble splitting and bed expansion were studied for all four types of particles for different superficial velocities. Group-B and D particles easily produced bubbles. However, Group-C and A particles gave very high bed expansion, and no clear bubbles were observed. Bed with the Group-D particles, the bubbles was large and some of the bubbles reached the diameter of the bed. Group-B particles gave smaller and on average more stable bubbles than Group-D particles. There was no bubble formation from Group-C and Group-A until the inlet superficial velocity was 25 times and 5 times larger, respectively, than their minimum fluidization velocities.

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“…Wang et al . [61] have attempted to extend the mechanism resulting in cohesive behavior for macrosized particles to nanosized particles.…”

Section: Introductionmentioning

confidence: 99%

Solid–solid reaction in a fluidized bed

Murthy

Reddy

Sankarshana

2011

Asia-Pacific J Chem Eng

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Solid-solid reactions, although of considerable industrial importance, have not received significant attention in the chemical engineering literature. In conventional method of manufacturing products using reactants in solid phase, the rate of heat transfer and rate of diffusion are very slow. In order to overcome these problems, an attempt is made to investigate these reactions employing a stirred fluidized bed. The addition reaction of phthalic anhydride and p-nitro aniline system that takes place between 80 and 120• C, forming phthaloyl derivative of p-nitro aniline is selected for the investigations. The reaction is conducted in a stainless steel column of 0.1 m diameter and 1-m height. The variables considered are reaction temperature, stirrer speed, flow rate of fluidizing medium, and static bed height. Experiments are performed using statistically designed factorial experiments. Data are used to find the model suitable to the mechanism of the reaction. Mathematical equations relating reaction parameters viz., steady state conversion, time for steady state conversion, reaction rate constant, and activation energy with operating variables are developed and activation energy is reduced from 14 kcal/mol reported in literature to less than 5.3 kcal/mol depending on operating conditions. The concept could be adopted for the manufacture of cement, and other materials with required modifications of experimental setup. 

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Nanoparticle fluidization and Geldart's classification

Cited by 70 publications

References 23 publications

Decoration of Carbon Nanotubes by Semiconducting or Metallic Nanoparticles using Fluidized Bed Chemical Vapour Deposition

Decoration of Carbon Nanotubes by Semiconducting or Metallic Nanoparticles using Fluidized Bed Chemical Vapour Deposition

Study of Fluidization Regimes using OpenFOAM Computational Fluid Dynamics

Solid–solid reaction in a fluidized bed

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