Multi-scale analysis of the influence of physicochemical parameters on the hydrodynamic and gas–liquid mass transfer in gas/liquid/solid reactors

Kherbeche, Abderrahmane; Milnes, J S; Jimenez, Mélanie; Dietrich, Nicolas; Hébrard, Gilles; Lekhlif, Brahim

doi:10.1016/j.ces.2013.06.025

Cited by 26 publications

(24 citation statements)

References 25 publications

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“…enlarging the average gas-liquid surface area so that more area is available for mass transfer [6,11,12]; iv. limiting gas-liquid mass transfer dissipation [6,13];…”

Section: Introductionmentioning

confidence: 99%

“…In order to quantify mass transfer around the confined sliding bubbles, a visualization technique based on a colorimetric method coupled with high-speed imaging was performed. This technique, developed by Dietrich et al, [36] and experimented by Kherbeche et al, [13]; Yang et al, [12]; and Kovats et al, [37] allows clear visualization of oxygen concentrations and an accurate gas-liquid mass transfer quantification.…”

Section: Introductionmentioning

confidence: 99%

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Hydrodynamics and gas-liquid mass transfer around a confined sliding bubble

Kherbeche

Mei

Thoraval

et al. 2020

Chemical Engineering Journal

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An experimental investigation of gas-liquid mass transfer in the wake of a confined air bubble sliding under an inclined wall in a 2D Hele-Shaw cell is reported. A colorimetric technique based on an oxygen-sensitive dye was used to visualize the oxygen transfer. Bubble velocities, shape eccentricities, interfacial areas and, for the first time, the instantaneous spatio-temporal distribution of oxygen concentration fields in the bubble wake, have been investigated for upper wall inclination angles of 10° ≤ α ≤ 60° and Archimedes numbers of 783 ≤ Ar ≤ 3221. Image processing has allowed, through a specific approach, a quantification of mass transfer. The calculation of the mass flux allowed the deduction of the liquid-side mass transfer coefficient kL. Experiments reveals that, at low angles of inclination, bubble velocities decelerates, shape eccentricities increased, and the instantaneous spatial and temporal distribution of oxygen concentration fields illustrated two distinct regions underneath the sliding bubble: a single vortex loop enclosing the near wake where oxygen is transferred, and a far wake containing oxygen in the form of a single long strip. When inclination angles and bubble sizes were increasing, velocities were increasing, the vortex elongated gradually until it disappears at high angles where total mass fluxes increased. This increase of bubble velocities has increased liquid-side mass transfer coefficient kL allowing a scaling law between the Sherwood number and the modified Archimedes number Ar.sin(α) to be proposed.

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“…enlarging the average gas-liquid surface area so that more area is available for mass transfer [6,11,12]; iv. limiting gas-liquid mass transfer dissipation [6,13];…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydrodynamics and gas-liquid mass transfer around a confined sliding bubble

Kherbeche

Mei

Thoraval

et al. 2020

Chemical Engineering Journal

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“…As the diffusion coefficient of the dye is 91 weak in comparison with that of oxygen in these liquids, it is possible to visualize the presence 92 of oxygen around these interfaces. Kherbeche et al, (2013) around bubbles at forming stage in a micro-channel. This paper proposes to apply this recent technique to a bubble rising in a quiescent liquid, which has previously been visualized only by 97 the PLIFI technique.…”

Section: Introduction 45mentioning

confidence: 99%

Visualisation of gas-liquid mass transfer around a rising bubble in a quiescent liquid using an oxygen sensitive dye

Dietrich

Hébrard

2018

Heat Mass Transfer

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21An approach for visualizing and measuring the mass transfer around a single bubble rising in a 22 quiescent liquid is reported. A colorimetric technique, developed by using 23 an oxygen sensitive redox dye was implemented. It was based on the reduction of the 24 colorimetric indicator in presence of oxygen, this reduction being catalysed by sodium 25 hydroxide and glucose. In this study, resazurin was selected because it offered various reduced 26 forms with colours ranging from transparent (without oxygen) to pink (in presence of oxygen). 27These advantages made it possible to visualize the spatio-temporal oxygen mass transfer around 28 rising bubbles. Images were recorded by a CCD camera and, after post-processing, the shape, 29 size, and velocity of the bubbles were measured and the colours around the bubbles mapped. A 30 calibration, linking the level of colour with the dissolved oxygen concentration, enabled colour 31 maps to be converted into oxygen concentration fields. A rheoscopic fluid was used to visualize 32 the wake of the bubbles. A calculation method was also developed to determine the transferred 33 oxygen fluxes around bubbles of two sizes (d = 0.82 mm and d = 2.12 mm) and the associated 34 liquid-side mass transfer coefficients. The results compared satisfactorily with classical global 35 measurements made by oxygen micro-sensors or from the classical models. This study thus 36 constitutes a striking example of how this new colorimetric method could become a remarkable 37 tool for exploring gas-liquid mass transfer in fluids. 38 39 40 41

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“…The oxygen‐sensitive dye used was resazurin which is a phenoxazin‐3‐one dye widely used for testing bacterial or yeast contamination in biological fluids and milk, and also identifying the semen quality by colorimetry since 1950s . Afterwards, this technique has been successfully implemented in other geometries, thus demonstrating its reliability to characterize the oxygen mass transfer and to elucidate the complex mechanism of gas–liquid mass transfer. Nevertheless, it should be pointed out that the kinetics data about the colorimetric reaction between oxygen and dihydroresorufin remain rare and that the occurrence of a possible enhancement of the gas–liquid mass transfer by this reaction has not been rigorously demonstrated.…”

Section: Introductionmentioning

confidence: 99%

Optical methods to investigate the enhancement factor of an oxygen‐sensitive colorimetric reaction using microreactors

et al. 2016

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao. Abstract: Visualization of mass transfer is a powerful tool to improve understanding of local phenomenon. The use of an oxygen-sensitive dye (colorimetric technique 1 ) has showed its relevancy for locally visualizing and characterizing gas-liquid mass transfer at different scales 2,3 . At present, the occurrence of a possible enhancement of the gas-liquid mass transfer by this reaction has not been yet demonstrated. This paper aims at filling this gap by evaluating the Hatta number Ha and the enhancement factor E associated with the oxygen colorimetric reaction when implementing in milli/micro channels. For that, as data on the kinetic of the colorimetric reaction are seldom in the literature, the reaction characteristic time was firstly estimated by carrying out experiments in a microchannel equipped with a micromixer. The diffusion coefficients of dihydroresorufin and O 2 were then determined by implementing two original optical methods in a specific coflow microchannel device, coupled with theoretical modelling. The knowledge of these parameters enabled at last to demonstrate that no enhancement of the gas-liquid mass transfer by this colorimetric reaction existed.Complementary information about the reliability of the colorimetric technique to characterize the gasliquid mass transfer in milli/micro systems was also given.

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Multi-scale analysis of the influence of physicochemical parameters on the hydrodynamic and gas–liquid mass transfer in gas/liquid/solid reactors

Cited by 26 publications

References 25 publications

Hydrodynamics and gas-liquid mass transfer around a confined sliding bubble

Hydrodynamics and gas-liquid mass transfer around a confined sliding bubble

Visualisation of gas-liquid mass transfer around a rising bubble in a quiescent liquid using an oxygen sensitive dye

Optical methods to investigate the enhancement factor of an oxygen‐sensitive colorimetric reaction using microreactors

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