Understanding the formation process of the liquid slug in ...
Hydrodynamic characterization of gas-liquid-liquid slug flow and ... 2014 poster_J Yue.pdf · 1...
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Pressure drop model in three-phase slug flow The developed model takes into account separate pressure drop contributions from the water slugs, the body and end caps of the pseudo-homogeneous ‘nitrogen-in-decane’ droplets. Hydrodynamic characterization of gas-liquid-liquid slug flow and parallel-slug flow through a glass microfluidic chip Jun Yue 1 , Evgeny V. Rebrov 2 , Jaap C. Schouten 1 1 Laboratory of Chemical Reactor Engineering, Eindhoven University of Technology, The Netherlands 2 School of Chemistry and Chemical Engineering, Queen's University Belfast, United Kingdom More information at: Yue et al., Lab Chip, 2014, 14, 1632–1649 (figures reproduced with permission from The Royal Society of Chemistry). E-mail: [email protected], [email protected] Introduction Gas-liquid-liquid flow in microfluidic and microreactor systems has important applications in the production of double emulsions, intensification of liquid-liquid extraction by gas agitation, kinetic studies in organic synthesis via aqueous catalysis in three-phase mode (e.g., hydrogenation, hydroformylation, oxidation). The currently inadequate understanding on the fundamental transport rules of gas-liquid-liquid mixtures in microchannels renders the system design far from being optimized. Here we report gas-liquid-liquid slug flow and parallel-slug flow in a microfluidic chip and develop pressure drop models thereof under small capillary numbers (Ca ≪ 0.1) and Weber numbers (We ≪ 1). Experimental N 2 -decane-water flow was tested in a glass microfluidic chip having a serpentine microchannel (hydraulic diameter being 98 μm) connected to a cross-flow mixer. The effective microchannel length under test is 14 cm (from the cross-flow mixer to port D via segments 1−6; ports E and F are blocked). Pressure drop in the chip was obtained as the difference in pressure measurements with and without the chip under identical flow rate conditions. Pieken in de Delta A 1 2 3 4 5 6 7 30 31 35 B C D E F Water syringe pump Check valve Capillary 1 Decane syringe pump Check valve Capillary 3 Capillary 2 Pressure sensor Pressure barrier Mass flow controller N 2 cylinder Capillary 4 N 2 Decane Liquid collector Water W H Microfluidic chip Microscope W = 300 μm H = 60 μm d h = 98 μm Superficial velocity range j G,STP : 30 − 91 mm/s j W : 0.6 − 41 mm/s j D : 0.6 − 41 mm/s Gas-liquid-liquid flow pattern Three-phase slug flow can be seen as a superimposition of both decane–water and N 2 –decane slug flows observed in the chip when the flow of N 2 or water, respectively, was set at zero. Parallel-slug flow can be seen as a superimposition of decane– water parallel flow and N 2 –decane slug flow observed in the chip under the corresponding two-phase flow conditions. Cross-flow mixer and downstream location Middle part of segment 4 Water Decane N 2 Decane N 2 Water Cross-flow mixer Decane N 2 Water Water Decane N 2 Middle part of segment 4 G-L-L slug flow G-L-L parallel-slug flow 0.1 1 10 100 0.1 1 10 100 Three-phase slug flow Transitional flow pattern Parallel-slug flow j D [mm/s] j W [mm/s] Nitrogen-decane-water flow j G,STP = 30.4 mm/s 0.1 1 10 100 0.1 1 10 100 Slug flow Parallel flow that breaks into slug flow Parallel flow j D [mm/s] j W [mm/s] Decane-waterflow Cross-flow mixer Water Decane Decane Water Cross-flow mixer Water Decane Water Decane Right part of segment 4 Right part of segment 4 L-L slug flow L-L parallel flow The ‘nitrogen-in-decane’ droplet is assumed with an effective viscosity (μ D ) specified by the McAdams mixture viscosity correlation: Symbols C laminar friction constant, obtained as 75.33 via CFD simulation c 1 geometrical parameter, taken as 16 based on the work of Fuerstman et al. (Lab Chip, 2007, 7, 1479-1489) U D ‘nitrogen-in-decane’ droplet velocity, m/s U S water slug velocity, m/s x mass fraction of gas in the pseudo-homogeneous droplet μ C viscosity of the continuous phase, Pas σ interfacial tension between water and decane, N/m Ca capillary number (= μ water U D / σ) We Weber number (= d h U D 2 ρ water / σ ) Three-phase slug flow 0 20 40 60 80 0 20 40 60 80 This work Parity line ∆P tot, model [kPa] ∆P tot, exp [kPa] L D L S N 2 Water Decane Pressure drop model in parallel-slug flow The developed model takes into account separate pressure drop contributions from the local decane–water parallel flow region (i.e., the decane slug) and the region with bubbles. 0 20 40 60 80 0 20 40 60 80 This work Parity line ∆P tot, model [kPa] ∆P tot, exp [kPa] Parallel-slug flow Decane W L S L B N 2 W 1 Water Interfacial position (or pressure drop) in decane-water parallel flow is described by assuming flow of one fluid in the same channel. Presence of bubbles in an otherwise decane-water parallel flow did not change the interfacial position. W 1 H W W 1 W Water Decane Parallel flow (top photo view) (Cross-sectional view) W 1 H W One fluid flow W 1 H W One fluid flow 0 0.1 0.2 0.3 0.4 0.5 0.6 0 0.1 0.2 0.3 0.4 0.5 0.6 Experimental (decane-water paralle flow) Experimental (parallel-slug flow) Analytical equation (one fluid flow) Comsol simulation (one fluid flow) W 1 / W [-] Q 1 / Q [-] Symbols U B bubble velocity, m/s d e hydraulic diameter for bubble moving in decane (≈ d h ), m σ interfacial tension between nitrogen and decane, N/m Ca capillary number (= μ decane U B / σ) We Weber number (= d h U B 2 ρ decane / σ ) ( )( ) ( ) 2/3 water S G D W D G B e B tot 1 2 2 B S e 1 / 2 2 h L j j j j L d U L Ca P C C c L L H d d µ µ σ + + − ∆ = + + + Ca: 1×10 -3 – 3×10 -3 We: 7×10 -3 – 4×10 -2 Ca: 2×10 -3 – 7×10 -3 We: 1×10 -2 – 1×10 -1 tot S body caps P P P P ∆ =∆ +∆ +∆ tot S body caps P P P P ∆ =∆ +∆ +∆ ( ) 2/3 D D h D C S S tot 1 2 2 D S h h 2 2 L d U LU L Ca P C C c L L H d d µ µ σ − ∆ = + + + ( ) D G decane 1 / 1 / x x µ µ µ = + −
Transcript of Hydrodynamic characterization of gas-liquid-liquid slug flow and ... 2014 poster_J Yue.pdf · 1...
Pressure drop model in three-phase slug flow The developed model takes into account separate pressure drop contributions from the water slugs, the body and end caps of the pseudo-homogeneous ‘nitrogen-in-decane’ droplets.
Hydrodynamic characterization of gas-liquid-liquid slug flow and parallel-slug flow through a glass microfluidic chip Jun Yue1, Evgeny V. Rebrov2, Jaap C. Schouten1 1 Laboratory of Chemical Reactor Engineering, Eindhoven University of Technology, The Netherlands 2 School of Chemistry and Chemical Engineering, Queen's University Belfast, United Kingdom
More information at: Yue et al., Lab Chip, 2014, 14, 1632–1649 (figures reproduced with permission from The Royal Society of Chemistry). E-mail: [email protected], [email protected]
Introduction Gas-liquid-liquid flow in microfluidic and microreactor systems has important applications in the production of double emulsions, intensification of liquid-liquid extraction by gas agitation, kinetic studies in organic synthesis via aqueous catalysis in three-phase mode (e.g., hydrogenation, hydroformylation, oxidation). The currently inadequate understanding on the fundamental transport rules of gas-liquid-liquid mixtures in microchannels renders the system design far from being optimized. Here we report gas-liquid-liquid slug flow and parallel-slug flow in a microfluidic chip and develop pressure drop models thereof under small capillary numbers (Ca ≪ 0.1) and Weber numbers (We ≪ 1).
Experimental N2-decane-water flow was tested in a glass microfluidic chip having a serpentine microchannel (hydraulic diameter being 98 μm) connected to a cross-flow mixer. The effective microchannel length under test is 14 cm (from the cross-flow mixer to port D via segments 1−6; ports E and F are blocked). Pressure drop in the chip was obtained as the difference in pressure measurements with and without the chip under identical flow rate conditions.
Pieken in de Delta
A1
234567
3031
35
B
C
D
E
F
Water syringe pumpCheck valve
Capillary 1
Decane syringe pumpCheck valve
Capillary 3
Capillary 2
Pressure sensorPressure barrier
Mass flow controller
N2 cylinder
Capillary 4
N2
Decane
Liquid collector
Water
W
H
Microfluidic chip
Microscope
W = 300 μm H = 60 μm dh = 98 μm
Superficial velocity range jG,STP : 30 − 91 mm/s jW : 0.6 − 41 mm/s jD : 0.6 − 41 mm/s
Gas-liquid-liquid flow pattern Three-phase slug flow can be seen as a superimposition of both decane–water and N2–decane slug flows observed in the chip when the flow of N2 or water, respectively, was set at zero. Parallel-slug flow can be seen as a superimposition of decane–water parallel flow and N2–decane slug flow observed in the chip under the corresponding two-phase flow conditions.
Cross-flow mixer and downstream location
Middle part of segment 4
Water
DecaneN2
Decane N2 Water
Cross-flow mixer
Decane N2 Water
Water
DecaneN2
Middle part of segment 4
G-L-L slug flow G-L-L parallel-slug flow
0.1
1
10
100
0.1 1 10 100
Three-phase slug flowTransitional flow patternParallel-slug flow
jD [mm/s]
j W[m
m/s
]
Nitrogen-decane-water flowjG,STP = 30.4 mm/s
0.1
1
10
100
0.1 1 10 100
Slug flowParallel flow that breaks into slug flowParallel flow
jD [mm/s]
j W[m
m/s
]
Decane-water flow
Cross-flow mixer
Water
Decane
DecaneWater
Cross-flow mixer
Water
Decane
WaterDecane
Right part of segment 4 Right part of segment 4
L-L slug flow L-L parallel flow
The ‘nitrogen-in-decane’ droplet is assumed with an effective viscosity (μD) specified by the McAdams mixture viscosity correlation:
Symbols C laminar friction constant, obtained as 75.33 via CFD simulation c1 geometrical parameter, taken as 16 based on the work of
Fuerstman et al. (Lab Chip, 2007, 7, 1479-1489) UD ‘nitrogen-in-decane’ droplet velocity, m/s US water slug velocity, m/s x mass fraction of gas in the pseudo-homogeneous droplet μC viscosity of the continuous phase, Pas σ interfacial tension between water and decane, N/m Ca capillary number (= μwaterUD / σ) We Weber number (= dhUD
2ρwater / σ )
Three-phase slug flow
0
20
40
60
80
0 20 40 60 80
This workParity line
∆Ptot, model [kPa]
∆Pto
t, ex
p[k
Pa]
LD LS
N2 WaterDecane
Pressure drop model in parallel-slug flow The developed model takes into account separate pressure drop contributions from the local decane–water parallel flow region (i.e., the decane slug) and the region with bubbles.
0
20
40
60
80
0 20 40 60 80
This workParity line
∆Ptot, model [kPa]
∆Pto
t, ex
p[k
Pa]
Parallel-slug flow
Decane
W
LS LB
N2W1
Water
Interfacial position (or pressure drop) in decane-water parallel flow is described by assuming flow of one fluid in the same channel.
Presence of bubbles in an otherwise decane-water parallel flow did not change the interfacial position.
W1
H
W
W1
W
WaterDecane
Parallel flow (top photo view) (Cross-sectional view)
W1
H
W
One fluid flow
W1
H
W
One fluid flow
0
0.1
0.2
0.3
0.4
0.5
0.6
0 0.1 0.2 0.3 0.4 0.5 0.6
Experimental (decane-water paralle flow)Experimental (parallel-slug flow)Analytical equation (one fluid flow)Comsol simulation (one fluid flow)
W1 / W [-]
Q1
/ Q[-]
Symbols UB bubble velocity, m/s de hydraulic diameter for bubble moving in decane (≈ dh), m σ interfacial tension between nitrogen and decane, N/m Ca capillary number (= μdecaneUB / σ) We Weber number (= dhUB
2ρdecane / σ )
( )( ) ( ) 2/3water S G D W D G B e B
tot 12 2B S e
1 /
2 2h
L j j j j L d UL CaP C C cL L Hd d
µ µ σ + + −∆ = + +
+
Ca: 1×10-3 – 3×10-3
We: 7×10-3 – 4×10-2
Ca: 2×10-3 – 7×10-3
We: 1×10-2 – 1×10-1
tot S body caps P P P P∆ = ∆ + ∆ + ∆
tot S body caps P P P P∆ = ∆ + ∆ + ∆
( ) 2/3D D h DC S S
tot 12 2D S h h2 2
L d UL UL CaP C C cL L Hd d
µµ σ −∆ = + +
+
( )DG decane
1/ 1 /x x
µµ µ
=+ −
