Quantitative criteria to define flow patterns in micro-capillaries

Dessimoz, Anne-Laure; Raspail, Pauline; Berguerand, Charline; Kiwi‐Minsker, Lioubov

doi:10.1016/j.cej.2010.01.011

Cited by 35 publications

(18 citation statements)

References 20 publications

(46 reference statements)

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“…For these flow maps the flow pattern is defined by dispersed phase velocity only. This may be also used for gas-liquid flows in microchannels [27] and is applicable for liquidliquid flows when one of the liquids is dispersed and does not wet channel walls. Another way to derive a universal flow map is described by Waelchli et al [28], where authors used dimension analysis and P-theorem for gas-liquid flows.…”

Section: Introductionmentioning

confidence: 99%

Flow patterns of immiscible liquid-liquid flow in a rectangular microchannel with T-junction

Yagodnitsyna

Kovalev

Bilsky

2016

Chemical Engineering Journal

111

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Section: Introductionmentioning

confidence: 99%

Flow patterns of immiscible liquid-liquid flow in a rectangular microchannel with T-junction

Yagodnitsyna

Kovalev

Bilsky

2016

Chemical Engineering Journal

111

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“…Few works are devoted to serpentine or meandering microchannels even if such an arrangement is preferable as a mixer or a reactor for a long flow path on a small chip and for secondary flows to enhance mixing [20][21][22][23][24][25][26]. Bends and curved channels affect single-phase and two-phase flows differently [24].…”

Section: Introductionmentioning

confidence: 99%

Liquid-liquid two-phase flow patterns in ultra-shallow straight and serpentine microchannels

Sundén

2018

Heat Mass Transfer

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Water-butanol and water-hexane flows were visualized in ultra-shallow straight and serpentine microchannels with a crossjunction. At the inlet cross-junction, three major flow patterns including tubing/threading, dripping and jetting were mapped using the aqueous Capillary number versus the organic Weber number. Correspondingly, in the main microchannel, annular flow, slug flow and droplet flow were mapped using combined dimensionless numbers (Weber number times Ohnesorge number) of both phases. The flow pattern transitions were explained based on a force analysis, considering the phase flow rates, junction angle between the side feeding channels and the central feeding channel as well as aspect ratios. Compared to the straight microchannel, the dripping regime at the inlet junction and the slug flow occupy larger zones in serpentine microchannels because the centrifugal force tends to break up the organic annular core into slugs and droplets over the bends. Nomenclature Bo Bond number, (ρ a-ρ o)gd h 2 /γ Ca Capillary number, μu/γ Ce A dimensionless number representing the ratio of centrifugal to interfacial forces, ρu 2 d h 2 /(γR) d Channel diameter, μm d h Hydraulic diameter, μm g Gravitational acceleration, m/s 2 h Channel depth, μm j Superficial velocity, m/s L Channel length, m Oh Ohnesorge number, μ/(d h ργ) 0.5 Q Volumetric flow rate, ml/h q Flow rate ratio of organic to aqueous phases R Bending curvature radius of the channel centerline, m Re Reynolds number, ρjd h /μ u Average velocity (the overall volumetric flow rate of the two phases divided by the cross-sectional area), m/s w Channel width, μm We Weber number, ρj 2 d h /γ Greek symbols γ Interfacial tension, N/m μ Dynamic viscosity, Pa•s ρ Density, kg/m 3 Subscript ave Average a Aqueous phase c Continuous phase d Dispersed phase o Organic phase

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“…While the influence of the occurrence of bends in millimetric channels on the gas-liquid hydrodynamics (i.e. flow regime, mixing efficiency, interfacial area) has been highlighted by several authors (Günther et al, 2004;Fries and von Rohr, 2009;Dessimoz et al, 2010), rare are at present the studies quantifying how curvatures affect the gas-liquid mass transfer (Roudet et al, 2011;Kuhn and Jensen, 2012). Roudet et al (2011) showed that, when compared to a straight channel of identical compactness and sectional-area, the meandering channel induced: (i) a delay in the transition from Taylor to annular-slug regimes; (ii) a rise of 10-20% in bubble lengths while conserving almost identical slug lengths; (iii) higher deformations of bubble nose and rear due to centrifugal forces (bends).…”

Section: Introductionmentioning

confidence: 99%

Local investigations on the gas-liquid mass transfer around Taylor bubbles flowing in a meandering millimetric square channel

Yang

Loubière

Dietrich

et al. 2017

Chemical Engineering Science

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Gas-liquid mass transfer around Taylor bubbles moving in a meandering millimetric square channel was locally visualized and characterized in the present study. For that, the colorimetric technique proposed by Dietrich et al. (2013) was implemented. With this technique, the evolution of equivalent oxygen concentration fields in the liquid slugs passing through one and several bends was firstly described. In particular, it was observed how the flow structure (recirculation zones) inside the liquid slugs were twisted and split by the periodic bends (centrifugal effect), until reaching, after several bends, a uniform O 2 concentration inside the liquid slugs. The influence of the ''turning point", joining two ''straight" sections of meandering channel was also highlighted: a slowing down of the gas-liquid mass transfer was clearly shown. Volumetric mass transfer coefficients were determined at last by fitting the experimental axial profiles of averaged oxygen concentrations in the liquid slugs (before the turning point) with the ones predicted by a classical plug-flow model.

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Quantitative criteria to define flow patterns in micro-capillaries

Cited by 35 publications

References 20 publications

Flow patterns of immiscible liquid-liquid flow in a rectangular microchannel with T-junction

Flow patterns of immiscible liquid-liquid flow in a rectangular microchannel with T-junction

Liquid-liquid two-phase flow patterns in ultra-shallow straight and serpentine microchannels

Local investigations on the gas-liquid mass transfer around Taylor bubbles flowing in a meandering millimetric square channel

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