Effect of Amplitude on Mass Transport, Void Fraction and Bubble Size in a Vertically Vibrating Liquid-Gas Bubble Column Reactor

Still, Adam L.; Ghajar, Afshin J.; O’Hern, Timothy J.

doi:10.1115/fedsm2013-16116

Cited by 6 publications

(7 citation statements)

References 19 publications

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“…Vibrating BCR are particularly sensitive to this issue, because the vibrations generate potentially significant disturbances on the free surface. Consequently, it is common to float a closed-cell polystyrene foam (e.g., Styrofoam) disk on the free surface to dampen the interface and make measurement of the column height easier. ,, …”

Section: Review Of Common Experimental Methodsmentioning

confidence: 99%

“…There are generally two common methods to oscillate a bubble column in the literature. The first method involves shaking the entire column, as illustrated in Figure (left); similar designs have been used by many researchers. ,,,, The alternative method applies vibration directly to the fluid with the column stationary through a piston-type device, ,,, as shown in Figure (right), using a resonating device that is placed in the fluid or pulsing air . There are advantages and disadvantages to using either method; these considerations will be briefly discussed here.…”

Section: Review Of Common Experimental Methodsmentioning

confidence: 99%

“…Houghton studied particles suspended in an oscillating velocity field by applying a force balance to a particle (gas phase in bubbly flow) in a velocity field u ( u = A ω cos( ωt ), where A is the amplitude, ω is the radian frequency) and more details about this field are provided in the work of Still . This analysis decomposes to a linearized steady-state solution similar to a Mathieu equation when the transient drag effects approach zero.…”

Section: History Of Vibrating Bubble Column Reactor (Bcr) Researchmentioning

confidence: 99%

“…While some additional research expanded the theory, minimal research effort focused on this phenomena until the early 2000s. A summary of the primary studies spanning this range is provided in Table , along with the primary measurements from each study. − Recent research has gone so far as to develop theoretical, physics-based models to predict mass transfer and void fraction in these systems. While there is a nontrivial body of work on vibrating BCRs, to date, the parameter space has been explored in a rather haphazard fashion.…”

Section: Introductionmentioning

confidence: 99%

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Review of Bubble Column Reactors with Vibration

Elbing

Still

Ghajar

2016

Ind. Eng. Chem. Res.

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Vibrating a bubble column reactor can increase the gas holdup (void fraction), as well the mass-transfer rate. Since the seminal work in the 1960s, there has been minimal effort focused on this topic until the early 2000s. Currently there are several groups studying this problem making advancements in our fundamental understanding of the process with detailed experiments, theoretical analyses, and physics-based models. However, throughout the literature, there are inconsistencies with both experimental results and proposed scaling of the fundamental properties, as well as minimal data spanning the parameter space. This review serves as an overview of key works from the 1960s and the 2000s, as well as to identify these inconsistencies between key studies. Recommendations for how to proceed with future work is provided with an emphasis on defining the parameter space in terms of the Reynolds number and the Froude number.

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Section: Review Of Common Experimental Methodsmentioning

confidence: 99%

Section: Review Of Common Experimental Methodsmentioning

confidence: 99%

Section: History Of Vibrating Bubble Column Reactor (Bcr) Researchmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Review of Bubble Column Reactors with Vibration

Elbing

Still

Ghajar

2016

Ind. Eng. Chem. Res.

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“…Note that in Equation 7, p 0 is the ambient pressure and g is the gravitational acceleration. The transient buoyancy number is the product of scaled vibration acceleration (Aω 2 /g) and scaled vibration pressure amplitude (ρ L HAω 2 /p 0 ) and has been widely used in vibrating bubble column research to identify the levitation condition [33][34][35][36][37][38][39]; in more recent studies, Bj was used to scale the void fraction and mass transfer in vibrating bubble columns [21,25,[40][41][42][43][44].…”

Section: Effect Of Vertical Vibration On Bubble-induced Mixingmentioning

confidence: 99%

Effect of Vertical Vibration on the Mixing Time of a Passive Scalar in a Sparged Bubble Column Reactor

Mohagheghian

Ghajar

Elbing

2020

Fluids

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The present study used a sparged bubble column to study the mixing of a passive scalar under bubble-induced diffusion. The effect of gas superficial velocity (up to 69 mm/s) and external vertical vibrations (amplitudes up to 10 mm, frequency <23 Hz) on the mixing time scale were investigated. The bubble-induced mixing was characterized by tracking the distribution of a passive scalar within a sparged swarm of bubbles. Void fraction and bubble size distribution were also measured at each test condition. Without vibrations (static), the bubble column operated in the homogenous regime and the mixing time scale was insensitive to void fraction, which is consistent with the literature. In addition, the temporal evolution of the static column mixing was well approximated as an error function. With vertical vibrations at lower amplitudes tested, the bubble-induced mixing was restrained due to the suppression of the liquid velocity agitations in the bubble swarm wake, which decelerates mixing. Conversely, at higher amplitudes tested, vibration enhanced the bubble-induced mixing; this is attributed to bubble clustering and aggregation that produced void fraction gradients, which, in turn, induced a mean flow and accelerated the mixing. The vibration frequency for the range studied in the present work did not produce a significant effect on the mixing time. Analysis of the temporal evolution of the concentration of the passive scalar at a fixed point within the column revealed significant fluctuations with vibration. A dimensionally reasoned correlation is presented that scales the non-dimensional mixing time with the transient buoyancy number.

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Sulfided Homogeneous Iron Precatalyst for Partial Hydrogenation and Hydrodesulfurization of Polycyclic Aromatic Model Asphaltenes

et al. 2020

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Here, we report the first study to use Fe 2 S 2 (CO) 6 as a well-defined petroleum-soluble precatalyst for partial hydrogenation of polycyclic aromatic and heteroaromatic compounds, including pyrene, phenanthrene, naphthalene, and benzothiophene. The in situ-generated heterogeneous catalyst was characterized using a combination of thermogravimetric analysis (TGA), combustion analysis (CHNS), Fourier transform infrared (FT-IR) spectroscopy, scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy-energy dispersive Xray (SEM-EDX). Catalytic performance of Fe 2 S 2 (CO) 6 was evaluated in a batch microreactor coupled with an agitator, varying reaction temperature, pressure, and precatalyst loading. The active phase, consisting of iron sulfide nanoparticles, was prepared from purified Fe 2 S 2 (CO) 6 in toluene; no sulfur additive is required. The results demonstrate that a "presulfided" iron catalyst leads to partial hydrogenation of polycondensed aromatics under moderate conditions, with naphthalene showing only low conversion. Activated carbon, γ-alumina, and activated silica are all effective dispersants for the Fe precursor. The reactivity shows self-consistent substrate dependence, varying with the resonance energy stabilization of the starting compounds and partially saturated intermediates coupled with the surface adsorption enthalpy of the aromatic ring system. The active catalyst derived from this precursor exhibits higher catalytic activity than commercial iron sulfide precatalysts. Importantly, the catalyst is active for hydrodesulfurization (HDS) of benzothiophene, albeit modestly so.

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Effect of Amplitude on Mass Transport, Void Fraction and Bubble Size in a Vertically Vibrating Liquid-Gas Bubble Column Reactor

Cited by 6 publications

References 19 publications

Review of Bubble Column Reactors with Vibration

Review of Bubble Column Reactors with Vibration

Effect of Vertical Vibration on the Mixing Time of a Passive Scalar in a Sparged Bubble Column Reactor

Sulfided Homogeneous Iron Precatalyst for Partial Hydrogenation and Hydrodesulfurization of Polycyclic Aromatic Model Asphaltenes

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