Real‐Time Visualization of Internal and External Concentration Fields in Multiphase Systems via Laser‐induced Fluorescence and Rainbow Schlieren Deflectometry During and After Droplet Production

Heine, Jens Stefan; Schulz, Joschka M.; Junne, Henning; Böhm, Lutz; Kraume, Matthias; Bart, Hans‐Jörg

doi:10.1002/cite.202000135

Cited by 9 publications

(4 citation statements)

References 33 publications

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“…In addition, since the release and establishment of said document, significant progress has been achieved, especially in terms of measurement technology. (Laser-)Optical methods such as particle image velocimetry (PIV) [3,4], laser induced fluorescence (LIF) [5][6][7] and the shadowgraphy method [8,9] have become the standard for fluid flow investigation, alongside numerical simulations via computational fluid dynamics (CFD) [10][11][12][13][14][15]. Internationally, the encyclopedic Handbook of Industrial Mixing has been published, documenting the progress in understanding mixing processes in recent decades and providing at least some basic construction guidelines for multistage impellers [16,17].…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Investigation and Visualization of Flow Fields in Stirred Tank Reactors Using a Fluorescence Tracer Method

Matzke

Behrens

Steins

et al. 2022

Chemie Ingenieur Technik

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In this study, flow fields in stirred tank reactors are investigated by a fluorescence tracer method. For these measurements, a fluorescent dye is inserted into a stirred tank reactor and distributed by the impeller flow, following the characteristic main circulation pathways. By this means, the main flow fields can be detected and visualized. Originally developed and used for the investigation of viscoelastic fluids, the method was adapted for Newtonian fluids with low viscosity in this study, with impeller installation height and impeller Reynolds numbers selected as influencing parameters. The resulting flow fields in both single-and double-impeller setups match the known structures from literature excellently. Therefore, the developed fluorescence tracer method has proven to be a promising supplement to the established repertoire of fluid investigation methods, with little effort in both experiment itself as well as the following data analysis steps.

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Section: Theoretical Backgroundmentioning

confidence: 99%

Investigation and Visualization of Flow Fields in Stirred Tank Reactors Using a Fluorescence Tracer Method

Matzke

Behrens

Steins

et al. 2022

Chemie Ingenieur Technik

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“…46 In this line, the recent studies based on noninvasive techniques, viz. confocal Raman spectroscopy, 14 planar laserinduced fluorescence, 11,13 Schlieren optical method, 12 etc., contribute to the improved understanding in terms of visualization of interfacial flow and concentration field in the drop. Common observation is that the interfacial instability is more prone to occur at higher initial concentrations of the solute and, thereby, results in the greater mass transfer due to a higher surface renewal rate of the solute at the interface.…”

Section: Introductionmentioning

confidence: 99%

“…Previously, it has been shown that 10–50% − and even 80% of the overall mass transfer occurs during drop formation, due to the very high concentration gradient in this stage. Thus, with the aim of evaluating early-stage mass transfer coefficient, the formation of a single drop has been studied by a few authors, using experiments, − analytical models, − and recently, numerical simulations. − …”

Section: Introductionmentioning

confidence: 99%

Understanding the Effects of Physical Properties of Composite Drop on its Formation Dynamics in Presence of Interfacial Mass Transfer

Khan,

Kulkarni

2024

Ind. Eng. Chem. Res.

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Dynamics of drop formation is studied in presence of interfacial mass transfer through controlled flow visualization experiments and lumped force balance based model. Experiments were conducted using eight different combinations of ternary systems, involving variations in initial composition and physical properties of drop phase over a broad range. A new image analysis method is reported to accurately measure the size of deformed, nonaxisymmetric drops. Based on flow visualization and analysis of drop shape, four modes of drop formation are identified, including (i) mass transfer free mode, (ii) interfacial instability mode (Marangoni effects), (iii) dripping, and (iv) jetting, with progressively increasing solute concentrations. Exceptions to these modes are observed for tetrahydrofuran−toluene and tetrahydrofuran− benzene mixtures, in which the drop remains in mass transfer free mode even in presence of higher solute concentrations. Model predictions of real time change in drop volume show excellent match with experimental results for all of the systems under study. The analysis of force balance implies that the interplay between (i) surface tension force and (ii) the combination of buoyancy and force due to kinetic energy controls the drop detachment time as well as the final drop volume. Therefore, for identical operating conditions, transition in drop formation time occurs from 4 s to 65 ms, depending on the density difference and interfacial tension between contacting phases. The present findings provide detailed insights into the formation dynamics of composite drops, which are commonly encountered in liquid−liquid extraction and various multiphase operations.

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“…In such cases, the transferring component has an additional and undefined reservoir within the capillary. Contact with a capillary can even trigger effects caused by gradients in interfacial tension, such as Marangoni convection [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

Drop Dissolution Intensified by Acoustic Levitation

Ruiken,

Villwock,

Kraume

2024

Micromachines

Self Cite

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Acoustic levitation can provide significant benefits for many fundamental research questions. However, it is important to consider that the acoustic field influences the measurement environment. This work focuses on the dissolution of immobilised drops using acoustic levitation in liquid–liquid systems. Previous work demonstrated that the acoustic field of standing waves impacts mass transfer by affecting the spread of dissolved substances in the continuous phase in two distinct ways: (I) solutes may either pass through nodal planes of the standing waves or (II) not pass. The binary systems examined for case (I) are 1-hexanol–water and 1-butanol–water, and for case (II), n-butyl acetate–water and toluene–water. This work quantifies the intensification effect of acoustic levitation on dissolution for the two types of behaviour, by comparing them with reference measurements of mechanically attached dissolving drops. The system was designed to ensure minimal intensification. The minimum intensification of mass transfer for levitating drops in the used setup of case (I) was 25%, and for case (II), it was 65%, both increasing with decreasing surface-equivalent diameter. With this understanding, acoustic levitation can be used more accurately in the field of mass transfer studies.

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Real‐Time Visualization of Internal and External Concentration Fields in Multiphase Systems via Laser‐induced Fluorescence and Rainbow Schlieren Deflectometry During and After Droplet Production

Cited by 9 publications

References 33 publications

Investigation and Visualization of Flow Fields in Stirred Tank Reactors Using a Fluorescence Tracer Method

Investigation and Visualization of Flow Fields in Stirred Tank Reactors Using a Fluorescence Tracer Method

Understanding the Effects of Physical Properties of Composite Drop on its Formation Dynamics in Presence of Interfacial Mass Transfer

Drop Dissolution Intensified by Acoustic Levitation

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