Experimental investigations of non‐Newtonian/Newtonian liquid‐liquid flows in microchannels

Roumpea, Evangelia; Chinaud, Maxime; Angeli, Panagiota

doi:10.1002/aic.15704

Cited by 40 publications

(19 citation statements)

References 48 publications

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“…The intensity fields for Qtot= 5 μL/min in the aqueous slug and in the organic plug are lower and higher, respectively, when compared to the other two flow rates. The concentration fields in the main channel seem to follow the internal circulation patterns expected in both the slugs and plugs [33]. This is more evident from the concentration field of 〈I org 〉 at Qtot=10 μL/min.…”

Section: Extraction Efficiency (%Eeff)mentioning

confidence: 63%

Studies on mass transfer of europium(III) in micro-channels using a micro Laser Induced Fluorescence technique

Angeli

Tsaoulidis

Weheliye

2019

Chemical Engineering Journal

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The mass transfer of europium(III) from an aqueous to an organic phase was studied in a quartz microchannel (internal diameter of 200 μm) using a novel micro Laser Induced Fluorescence (micro-LIF) technique. Europium(III) was extracted from a 1M nitric acid solution into an organic solution of TBP(1.2M)/CMPO(0.2M) in Exxsol D80. For the flow rates investigated plug flow was established. An experimental and data processing methodology was developed to calculate concentration profiles from the fluorescing light intensity profiles in both phases at different locations along the microchannel. In particular, the effect that the high light intensity of the organic phase has on the measurements in the aqueous phase was taken into account. Mass transfer was found to be significant in the beginning of the channel close to the inlet (1 mm distance) with extraction percentages varying between 20 to 40% depending on the total flow rate. High extraction efficiency (~80%) was achieved at short residence times (in the first 6 s), while the overall volumetric mass transfer coefficients varied between 0.05 and 3.3 s-1 .

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Section: Extraction Efficiency (%Eeff)mentioning

confidence: 63%

Studies on mass transfer of europium(III) in micro-channels using a micro Laser Induced Fluorescence technique

Angeli

Tsaoulidis

Weheliye

2019

Chemical Engineering Journal

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“…Note that the film thickness h is the only free parameter of the problem and can be determined, for example, by experiments (see, e.g., Roumpea et al, 2017) or by theory-based correlations (see Bretherton, 1961;Hodges et al, 2004;Picchi et al, 2018), where the film thickness is expressed as a function of the capillary number and the dimensionless parameters of the system, h = h (Ca, M, …). The problem then is closed with the following relation between the average velocities:…”

Section: 1029/2018wr023172mentioning

confidence: 99%

“…Note that the film thickness h is the only free parameter of the problem and can be determined, for example, by experiments (see, e.g., Roumpea et al, ) or by theory‐based correlations (see Bretherton, ; Hodges et al, ; Picchi et al, ), where the film thickness is expressed as a function of the capillary number and the dimensionless parameters of the system, h = h ( C a , M ,…). The problem then is closed with the following relation between the average velocities:

{〈 {\overset{bold-italicu}{true}}_{1} 〉}_{ℬ_{1}} = ℓ {〈 {\overset{bold-italicu}{true}}_{1} 〉}_{ℬ_{1 normalP}} + false(1 - ℓ false) {〈 {\overset{bold-italicu}{true}}_{1} 〉}_{ℬ_{1 normalS}},

{〈 {\overset{bold-italicu}{true}}_{2} 〉}_{ℬ_{2}} = ℓ {〈 {\overset{bold-italicu}{true}}_{2} 〉}_{ℬ_{2 normalP}},

where

{〈 {\overset{bold-italicu}{true}}_{1} 〉}_{ℬ_{1 normalS}}

is the average velocity in the single‐phase region, (1 − ℓ ), equal to the mixture velocity (Fabre & Line, ; Picchi et al, ) as

{〈 {\overset{bold-italicu}{true}}_{1} 〉}_{ℬ_{1 boldS}} = S_{1 boldP} {〈 {\overset{bold-italicu}{true}}_{1} 〉}_{ℬ_{1 boldP}} + false(1 - S_{1 boldP} false) {〈 {\overset{bold-italicu}{true}}_{2} 〉}_{ℬ_{2 boldP}} .

…”

Section: Impact Of Pore‐scale Flow Regimes On the Upscaled Equationmentioning

confidence: 99%

The Impact of Pore‐Scale Flow Regimes on Upscaling of Immiscible Two‐Phase Flow in Porous Media

Picchi

Battiato

2018

Water Resources Research

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Empirical or theoretical extensions of Darcy's law for immiscible two‐phase flow have shown significant limitations in properly modeling the flow at the continuum scale. We tackle this problem by proposing a set of upscaled equations based on pore‐scale flow regimes, that is, the topology of flowing phases. The incompressible Navier‐Stokes equation is upscaled by means of multiple‐scale expansions and its closures derived from the mechanical energy balance for different flow regimes at the pore scale. We also derive the applicability conditions of the upscaled equations based on the order of magnitude of relevant dimensionless numbers, that is, Eotvos, Reynolds, capillary, Froude numbers, and the viscosity and density ratio of the system, as well as a set of closures valid for the basic flow regimes of low Eotvos number systems, that is, core‐annular and plug and drop traffic flows. We provide analytical expressions for the relative permeability of the wetting and nonwetting phases in different flow regimes and demonstrate that the effect of the flowing‐phases topology on the relative permeabilities is significant. Finally, we show that the classical two‐phase Darcy law is recovered for a limited range of operative conditions, while specific terms accounting for interfacial and wall interactions should be incorporated to accurately model ganglia or drop traffic flow.

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“…However, they identified a transition point at a critical value of capillary number, above which the shear stress effect has to be accounted for. Extensive work has been performed over the last decades in an attempt to describe and characterise the break-up mechanism in a microfluidic T-junction, both in Newtonian and non-Newtonian systems [1][2][3][4][5][6][7][8][9]. Droplets are detached from the dispersed phase threads penetrating the continuous phase, either near the junction or several widths downstream, depending on the flow rates, the fluid properties, and the geometrical characteristics of the system [4,5].…”

Section: Introductionmentioning

confidence: 99%

Examining the Effect of Flow Rate Ratio on Droplet Generation and Regime Transition in a Microfluidic T-Junction at Constant Capillary Numbers

2018

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The focus of this work is to examine the effect of flow rate ratio (quotient of the dispersed phase flow rate over the continuous phase flow rate) on a regime transition from squeezing to dripping at constant capillary numbers. The effect of the flow rate ratio on the volume of droplets generated in a microfluidic T-junction is discussed, and a new scaling law to estimate their volume is proposed. Existing work on a regime transition reported by several researchers focuses on the effect of the capillary number on regime transition, and the results that are presented in this paper advance the current understanding by indicating that the flow rate ratio is another parameter that dictates regime transition. In this paper, the transition between squeezing and dripping regimes is reported at constant capillary numbers, with a transition region identified between squeezing and dripping regimes. Dripping is observed at lower flow rate ratios and squeezing at higher flow rate ratios, with a transition region between the two regimes at flow rate ratios between 1 and 2. This is presented in a flow regime map that is constructed based on the observed mechanism. A scaling model is proposed to characterise droplet volume in terms of flow rate ratio and capillary number. The effect of flow rate ratio on the non-dimensional droplet volume is presented, and lastly, the droplet volume is expressed in terms of a range of parameters, such as the viscosity ratio between the dispersed and the continuous phase, capillary number, and the geometrical characteristics of the channels.

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Experimental investigations of non‐Newtonian/Newtonian liquid‐liquid flows in microchannels

Cited by 40 publications

References 48 publications

Studies on mass transfer of europium(III) in micro-channels using a micro Laser Induced Fluorescence technique

Studies on mass transfer of europium(III) in micro-channels using a micro Laser Induced Fluorescence technique

The Impact of Pore‐Scale Flow Regimes on Upscaling of Immiscible Two‐Phase Flow in Porous Media

Examining the Effect of Flow Rate Ratio on Droplet Generation and Regime Transition in a Microfluidic T-Junction at Constant Capillary Numbers

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