EXPERIMENTAL INVESTIGA

Guided by:

Dr. U. K. Arun Kumar

(Assistant Professor)

Dept. of Chemical Eng.

In partial fulfilment

Depart

Malaviya Na

1

A

Project Report

On

TIGATION OF LIQUID LIQUID FLOW IN MICROCH

Submitted

Mukesh Kumar Yadav 2011

Jitendra Singh 2011

Mahendar Kumar Meena 201

Amandeep Yadav 20

Submitted

ent of the requirements of the degree of Bachelor o

Technology

In

Chemical Engineering

partment of Chemical Engineering

a National Institute of Technology, Jaipur

CHANNELS

itted by :

2011UCH1034

2011UCH158

2011UCH1587

2011UCH1004

lor of

2

DEPARTMENT OF CHEMICAL

ENGINEERING

MALAVIYA NATIONAL INSTITUTE OF TECHNOLOGY JAIPUR (302017) INDIA

CERTIFICATE

This is to certify that the project report entitled, EXPERIMENTAL

INVESTIGATION OF LIQUID LIQUID FLOW IN MICRO

CHANNELS has been completed and submitted by the VIII Semester

students Mukesh Kumar Yadav (2011uch1034), Jitendra

Singh(2011uch1583), Mahendar Kumar Meena(2011uch1587),

Amandeep Yadav(2011uch1004) under my guidance.

Guide & Supervisor

Dr. U. K. Arun Kumar

(Assistant Professor)

Department of Chemical Engineering

Malaviya National Institute of Technology Jaipur (302017).

3

DECLARATION

We hereby declare that the work proposed in the B.Tech Project Report entitled

EXPERIMENTAL INVESTIGATION OF LIQUID LIQUID FLOW IN MICROCHANNELS in partial

fulfillment of the requirement for the award of the degree of B.Tech in Chemical Engineering

submitted to the Department of Chemical Engineering , MALAVIYA NATIONAL INSTITUTE OF

TECHNOLOGY, JAIPUR, is an authentic of my carried out from July 2014 to June 2015 under the

supervision and guidance of Dr. U. K. Arun Kumar, Assistant Professor, Department of Chemical

Engineering, MNIT, Jaipur. Information used from literature and other sources in the present

thesis has been duly acknowledged by giving references at the appropriate places.

The matter embedded in this thesis has not been submitted by

(Mukesh Kumar Yadav) (Jitendra Singh)

(Mahendar Kumar Meena) (Amandeep Yadav)

Date:

The present work is an authentic carried out by these students refer my supervision. Try the

best of my knowledge, the matter embedded in this work has not been submitted in any other

University or Institute for the award of any Degree or Diploma.

Dr. U. K. Arun Kumar

Assistant professor

Department of Chemical Engineering,

MNIT Jaipur.

4

ACKNOWLEDGEMENT

We wish to express our deep sense of gratitude to our guide Dr. U.K. Arun Kumar, Assistant

Professor,Chemical Engineering, Malaviya National Institute of Technology, Jaipur who inspired

us to undertake this challenging project.

We would also like to express sincere gratitude to Dr. Suja George, Head of the Department,

Chemical Engineering and Prof. I.K. Bhatt,Director, Malaviya National Institute of Technology,

Jaipur for all the facilities provided in the department.

We extend thanks to Dr. Sushant Upadhyay, Project Coordinator, Department of Chemical

Engineering, for allocation of the desired project and timely assistance during various stages of

the project.

Finally we would like to thank all those people who directly or indirectly were responsible for

making our project a successful endeavor.

Mukesh Kumar Yadav Jitendra Singh

Mahendar Kumar Meena Amandeep Yadav

Department of Chemical Engineering

Malaviya National Institute of Technology, Jaipur

5

TABLE OF CONTENTS Page no. 1. INTRODUCTION 1.1) Introduction 7 1.2) Conventional Contactors used for Liquid-Liquid extraction 8 1.3) Advantages of Micro Structured Reactors over conventional reactors 9 1.4) Application of Microfluidics 11 1.5) Governing Dimensionless Numbers in micro channel 11 1.6) Governing Equations in micro channel 12

1.7) Mechanism of Mass Transfer in Slug Flow 13 1.8) Flow pattern in Liquid-Liquid micro channel system 14

2. LITERATURE REVIEW 15

3. OBJECTIVE 19

4. EXPERIMENTAL SECTION 20

5. OBSERVATIONS & CALCULATIONS 21

6. CONCLUSION 24

6. REFERENCES 25

6

ABSTRACT:

The hydrodynamics and the pressure drop of liquidliquid slug flow in round micro capillaries

are studied. Here the liquid liquid flow system is Toluene water. The slug lengths of the

alternating continuous and dispersed phases were measured as a function of the slug flow rate

(0.2 3ml/min.), the toluene to water flow ratio (0.1 3), and the micro capillary internal

diameter (0.5mm, 0.8mm, 1mm). We found the slug flow distribution is uniform throughout the

length of capillary.

7

Chapter 1

1.1 Introduction Microfluidics is the field of science that deals with technology and systems that can be used for the handling or processing of very small amount of fluids in the range of 10-9 to 10-18 liters. It is an interdisciplinary field which include engineering, chemistry, physics, nanotechnology, biochemistry and biotechnology. In microfluidics channels in the size range of ten to several hundred micrometer size is used. It mainly exploits the miniaturized size of the channels. It has a wide future applicability in the field of chemical and biotechnology to synthesize chemicals and separation process. Microfluidics emerged in the beginning of 1980s principally with the development of inkjet print heads. The principle of process intensification which aims to use green technology such as small, compact, energy efficient processes has led to the interest in micro-fluidics. In the recent years more interest in micro structured devices are shown which are expected to replace the existing manufacturing and separation processing in chemical and pharmaceutical industries (1).

Liquid-liquid extraction is a commonly used separation techniques used in refinery, pharmaceutical and chemical industries. Separation by Extraction contains three important stages. In the first stage two liquids which are partially or completely immiscible are mixed together in which emulsion drops are formed. The second is settling stage in which the liquids separate into two layers and form two clear layers. The final stage involves decanting of individual layers, separation of solute from the solvent and solvent recycle (2).

1.2 Conventional Contactors used for Liquid-Liquid extraction

The most important are

8

Mixer-Settler

Centrifugal extractors

Columns

In a mixer-settler aqueous and organic liquids are made to contact with each other in a mixer with agitation and it is allowed to settle in a settler with a shallow basin where liquids separate into two different layers and are decanted separately. In a centrifugal extractor, the immiscible liquids are mixed in an annular space between a stationary housing and a rotor. Centrifugal forces are used for separation of the two immiscible liquids. Columns can be divided into two categories- static columns and agitated columns. Packed column, sieve plate column and spray column are the example for static columns, whereas rotating disk contactor, Karr column, Kuhni column, Scheibel column and pulsed columns are example for agitated columns. The advantages and disadvantages of conventional contactors are listed in Table 1. A common disadvantage of these conventional equipment is non uniformity that occur due to the difficulties of the fundamental hydrodynamics (3).

Advantages Disadvantages Mixer Settler

Better contacting Investment cost is high Low maintenance Operation cost is high Simplicity

Centrifugal Contactors Liquids with low density difference can be used

Scaling up is difficult

Only small volume of solvent is required Mechanical complexity Rapid mixing can increase quality and product recovery

Maintenance cost is high

Advantages Disadvantages Static Columns

Easy operation Performance completely depends on packing materials

Lower cost Only limited range of flow rates can give good performance

Agitated Columns

9

Table 1. Advantages and disadvantages of conventional contactors

1.3 Advantages of Micro Structured Reactors over conventional reactors

The disadvantage of the conventional mass transfer equipment are very low interfacial area or surface area to volume ratio which is in the range 1000 m2/m3. High mass and heat transfer limitations which can result in very low productivity and selectivity in conventional reactors can be overcome using Micro Structured Reactors (MSR). The small channel dimensions available in the MSR results in high surface to volume ratios and increases internal mass transfer and external heat transfer. It also reduces the risk related with toxic and other hazardous materials due to the very low amount of substances being handled. Low residence time & hold ups of these kind of Micro Structured extraction techniques makes it an attractive substitute, both technical and economic terms to conventional arrangements. Micro structure contactors are advantages due to its high interfacial area i.e., around 1000 to 15000 m2/m3 and the internal circulation that reduces the diffusion distance eventually enhancing the mass transfer rate. Moreover micro structured contactors does not require mechanical parts for mixing (8).

Economy of using micro channel is evaluated in terms of power requirement which is defined as energy spent per unit volume of liquid in a continuous process. One of the important parameters for assessing technical reactors is power input. Table 2 shows a comparison of power input for MSR with other conventional extraction equipment.

Contactor Power input kJ/m3 of liquid Centrifugal extractors 850-2600

Impinging streams 280

Rotating disk impinging streams contactor 175-250

Mixer Settler 150-250

Impinging streams extractors 35-1500

Investment cost is low Small density differences cannot be separated easily

Performance is better Limited flow ratio can give good performance

Agitated extraction column

Capillary micro channel(I.D= 0.5Table 2.

Comparison of the rates of heat a

Figure 1. B

Comparison of mass transfer coeequipment with the micro contac

Contactor Agitated Contactor

Packed Bed Column (Pall/Raschig ring, Intalosaddles)

10

0.5-190

0.5-1 mm) 0.2-20 2. Power input for conventional contactors

t and mass transfer of various reactors is shown in

. Benchmarking of micro-structured reactors

oefficients and effective interfacial area of convenactor is shown in Table 3.

A (m2/m3) kLa (32-311 (48-83)

talox 80-450 (3.4-5)

in Fig 1.

entional extraction

a (s-1) 3)10-3

5) 10-3

11

RTL extractor (Grasser raining bucket)

90-140 (0.6-1.3) 10-3

Air operated two impinging jets reactors

350-900 0.075

Two impinging jets reactor 1000-3400 0.28

Capillary micro channel (I.D=0.5-1 mm)

830-3200 0.88-1.67

Table 3. Specific Interfacial area and overall mass transfer co-efficient for conventional contactors

1.4 Application of Microfluidics Micro Structured Reactor finds its applications in

Extraction Chemical Reactions Polymerase Chain Nano particle crystallization Protein folding Bio-process optimization Cell analysis Drug screening Clinical diagnostics

1.5 Governing Dimensionless Numbers in micro channel The dimensionless numbers that governs the flow in micro capillaries are Reynolds number, Webber number and Capillary number.

Reynolds Number=

=

12

Capillary Number=

=

Weber Number=

=

1.6 Governing Equations in micro channel

Equation of continuity:

+ . ( ) = 0 (1)

Equation of motion:

( )

+ . ( ) = -" + . [ $( + &)] + ' + ( (2)

Volume fraction equation:

*+

+ ., - = 0 (3)

With

= . . + - - ; $ = . $. + - $-

Where, , , V, p and F denote the mixture density, the mixture viscosity, the mixture velocity field, the pressure and the source term that represents the surface tension force, respectively.

1.7 Mechanism of Mass Transfer in Slug Flow

13

For Micro Structured Reactors two immiscible phases are required. The two phases can be either Liquid-Liquid or Gas-Liquid. As the feed are in the immiscible form, the product formed will also be in an immiscible form making separation easy. Water and kerosene are examples for inorganic and organic phases. The parameters that define the hydrodynamics of two phase flow are

Surface tension of fluid.

Viscosity of fluid.

Contact angle of the fluids with the reactor surface.

Geometry of the channel and the inlet section.

Channel arrangement relative to direction of gravity.

The transport of materials in liquid-liquid slug flow generated in micro-channel is enhanced by two phenomena i.e., internal circulation and interfacial diffusion. The shear generated between the wall of micro-channel and the axis of the slug generates internal circulation which helps in uniform distribution within the slugs. The mechanism of internal circulation also helps in reducing the boundary layer thickness across the interface. Thus the major concentration gradient exist at the interface which leads to shorter diffusion distance and faster mass transfer (10).

Figure 2. Mass transfer in slug flow

The mass transfer rate in a micro channel is largely dependent convection and diffusion behavior of the fluids. It also depend on internal circulations inside each slugs when it is flowing. Internal

circulation is formed due to shedecreased volume for transfer. Meffect of length of slug, ratio of t

mass transfer behavior.

1.8 Flow pattern in Liquid

Different Liquid-Liquid flow patt

1.8.1 Droplet Flow

Droplet flow is formed when thcompletely wets the wall of the

diameter of the capillary (5).

1.8.2 Slug flow

Slug flow is generated when theincludes plug or segmented or bof a liquid (among the 2) with thliquids. In this case the interfacforces. In slug flow, the two pha

bubbles. The equivalent diameterbullets (5).

1.8.3 Stratified Flow

It is also known as parallel flow

the liquids, one above the other a(5).

14

hear between the axis and reactor and the inside. Major reported studies on micro channels havef the flow rates, velocity of slug, micro channel g

id-Liquid micro channel system

attern are

the flow of dispersed phase is much lower thahe reactor. The diameter of the droplets are lesse

he flow rates of both the liquid are equal and low bullet flow. Slugs (capsules) are generated when the wall is higher compared to the interfacial teacial tension plays a dominant role than the vischases is transported through the channel as alter

ter of the bubble is larger than the channel diamete

w. This type of flow pattern is characterized by r as layers. Here the surface tension is dominated

de wall forces and ave focused on the l geometry etc.., on

than the fluid that sser than the inner

ower. Other names hen surface tension

tension of the two

iscous and inertial ternating elongated eter and appears as

y the flow of both ed by inertial force

15

Chapter 2

Literature Review

2.1 Literature Review

J.R Burns et al (2001) separated acetic acid from kerosene using slug flow. The experiments were conducted in a micro channel reactor made of glass material in a 380 m in width. Acid and base reaction were used as the basis of the study. Aqueous solution of KOH and NaOH with phenol red as pH indicator was used as the base having concentration ranging from 0.1 to 0.4 mol/L. Organic phase was prepared by mixing acetic acid in kerosene using Sudan III(red) and Sudan IV (blue). The aqueous Phase was comprised of KOH and NaOH solution. Both the organic and aqueous were made to flow in micro channel. Color change was used as the indicator for the completion of the reaction. It is reported that 97 % of acetic acid is separated. Volumetric mass transfer coefficient were reported in the order of 0.510-4 s-1

Kashid et al (2007) performed experiments on Liquid-Liquid Slug flow in a capillary along with wettability based flow splitter and showed that these are better than conventional contractors. LLE of 3 non reacting systems were used by them i) iodine in aqueous solution and kerosene ii) succinic acid in aqueous solution and n-butanol iii) acetic acid in kerosene and distilled water. 0.5, 0.75 and 1 mm capillary sizes were used. Capillary contactor was made of PTFE. The splitter worked on the principle of preferential wettability of a liquid on a solid material. Mass transfer co-efficient and extraction efficiency were used as the parameters for evaluating the performance of capillary contactor. They studied the effect of flow rates, capillary sizes and flow ratio on the liquid-liquid slug flow system as well as the Y splitter. They also compared the results with conventional contactors. They showed that with increase in the flow velocity for a given capillary, the extraction efficiency decreases. The extraction efficiency increases with decrease in solvent flow rates. An extraction efficiency of more than 90 % were achieved in all the cases. Specific interfacial area was found to be 4500-4800 m2/m3 and volumetric mass transfer co-efficient kLa (10-4 1/s) was found to be 0.31-0.98 for system (i) and ID=0.5 mm.

Dessimoz et al (2008) used two rectangular glass capillaries with an equivalent diameter of 269 & 400 m. Deionized water, hexane and dyed toluene was used as the immiscible fluids. T and

16

Y junctions were studied. Volumetric flow rates of both the fluids were in the range 1 and 6 ml/hr. The formation mechanism of slug and parallel flow and compared the mass transfer performances of two flow patterns. Slug flow and parallel flow were used for extraction and it was reported that slug flow contributes determined the mass transfer coefficients for parallel and slug flow using instantaneous neutralization (acidbase) reaction. The two flow patterns showed the same global volumetric mass transfer coefficients in the range of 0. 20. 5 s1.

Raimondi et al (2014) performed experiments of mass transfer with liquid-liquid slug flow in square micro channels. They carried out experiments in two micro reactors having square section of 0.21 and 0.30 mm width and were made from silicon and glass. The manufacturing technique used was photolithographic technique. High-aspect-ratio micro channels were fabricated in a silicon wafer by plasma etching using the deep reactive ion etching (DRIE) technique and the Bosch process. The introduction of the fluids were performed by syringes with stainless steel needles. A high-speed camera coupled with a binocular enables the visualization of the flow in the micro channel. Water/acetone/toluene two-phase system were used. Acetone was the solute which transfers from toluene (dispersed phase) to water (continuous phase).The concentration of acetone in the continuous phase is determined using secondary channels to extract this phase. In order to analyze continuous phase samples representative of this phase in the micro channel, half of its flow rate is constantly extracted. There were five secondary channels per micro reactor located at a distance of 2.4mm, 7.8mm, 17.6mm, 32.2 mm and 48.8 mm from the middle of the T-shape droplets generator. The total length of the main channel in which mass transfer occurs is 50.6 mm (from the droplets generator to the main outlet). The concentration of acetone in the continuous phase was determined by UV-spectrophotometry measurements. They measured droplet side mass transfer coefficient from the experimental concentration profiles. Volumetric mass transfer coefficient ranges from 0.72 to 8.44 s-1. The higher values are obtained for the higher droplets velocities, around 0.3 ms-1, most of the values are of the order of magnitude of 2 s-1 for droplets velocity ranging from 0.025 to 0.08 m s-1. They also performed interfacial area modelling.

Xu et al (2013) studied alkaline hydrolysis reaction by generating slug flow in micro channel. They extracted sodium hydroxide in water into n-butyl acetate. Interfacial area by snapshot method. They studied the effect of various parameters on slug length, mass transfer coefficient

17

and overall volumetric extraction rate quantitatively. They found a decreasing trend of volumetric mass transfer coefficient along the length of the channel. It was correlated volumetric mass transfer coefficient with different channel length. Specific interfacial area reported to be 4000-2250 m2/m3 and the volumetric mass transfer co-efficient, kLa (10-4 1/s) 0.05-0.35 in a 0.6 mm capillary.

Darekar et al (2014) carried out liquid-liquid extraction experiments in two diverse types of micro-channels using zinc sulfate, di-(2-ethylhexyl)-phosphoric-acid (D2EHPA) in dodecane which would be a typical reactive extraction system. They used T-junction serpentine micro channel and split and recombine micro channel. They studied the effects of organic to aqueous ratio and residence time on overall mass transfer coefficient. They also made an attempt to explain the L-L flow patterns with the help of high speed image acquisition system. They also reported correlations connecting overall mass transfer co-efficient for organic to aqueous ratio and velocity for both the micro channels. They got volumetric mass Transfer Co-efficient, kLa (10-4 1/s) as 5.41-0.02.

Kashid and Agar (2007) studied the effect of different operating conditions on the slug size, pressure drop, interfacial area, flow regimes gas been done. They measured the pressure drop along the Y shaped mixing element and the length of downstream capillaries were reported. Power required for creating interfacial area were also reported from the pressure loss over the Y junction. The results obtained from the power requirement calculation and interfacial area showed that the Micro Structure Reactor are much superior to conventional equipment in term of power input and specific energy per unit interfacial area generated.

Tsaoulidius et al (2013) studied the extraction of uranium (VI) from aqueous nitric acid solution by using tri-butyl phosphate dissolved in 1-butyl-3-methylimidazolium bis {(tri-fluoro methyl) sulfonyl} amide. They performed the experiments on a Teflon micro channel of 0.5 mm internal diameter. UV-Vis Spectroscopy was used to determine the concentration of dioxouranium (VI) in the aqueous and the ionic liquid phases. They studied the effect of initial nitric acid concentration (.01-3 M), phase flow rates and residence time and showed that extraction efficiency followed a marginally different trend. They also showed that mass transfer co efficient varied between 0.049 s-1 & 0.312 s-1

18

2.2 Overview of Literature Review Author

Year

System

Efficiency

Specific Interfacial

Area(m2/m3)

Volumetric mass Transfer Co-efficient, kLa (10-4 1/s)

Kashid et al.,

2007 1.Iodine in aqueous solution into kerosene

2.Acetic acid in kerosene into distilled water

>90 %

4500-4800 For system 1 with

film.(I.D-0.5 mm)

0.31-0.98 For system 1 with

film.(I.D-0.5 mm)

Burns and Ramshaw

2001 Kerosene in acetic acid into water

--

--

Order of magnitude-0.5

Dessimoz et

al.,

2008 Deionized water, dyed toluene and hexane

--

10,700-11,200

0.2-0.5

Kashid and Agar

2007 Water and Cyclohexane --

1450-1680 (I.D-0.5 mm)

Tsaoulidis et al.,

2013 Uranium(VI) from aqueous nitric acid solutions by tri butyl phosphate

78 %- 58%

78 %- 58%

0.312-0.132

Xu et al., 2013 Sodium hydroxide in water into n-butyl acetate

-- 4000-2250 (I.D-0.6 mm)

0.05-0.35

Darekar et

al.,

2014 Sodium hydroxide in water into n-butyl acetate

-- 2930(250 L serpentine micro

channel)

5.41-0.02

19

Raimondi et al.,

2014 Water, acetone and toluene

-- 4540-9600 (Square micro-channel- 0.30 mm)

0.72-8.44

Table 4: Overview of Literature Review

Objective:

To study the various parameter relations in liquid liquid flow in micro channel

Velocity distribution

Pressure drop

Flow regimes

Surface area

To study the hydrodynamics of liquid liquid flow in micro channel

Different diameter

Different length

Different flow rates

20

Experimental Section:

Experimental setup:

Procedure:

Fill both the syringes up to 10ml one is with water (dye) and the other with Toluene.

Connect the syringes to capillary with the help of Teflon tubes.

Set the flow rates for both the liquids.

Then start the experiment and observe the flow pattern.

If the slugs are of uniform length then take a picture of it.

Then by changing the flow ratio take observations.

21

Observations & Calculations:

1. Capillary internal diameter = 0.8mm

s. no. Water flow

rate(ml/min)

Toluene flow

rate(ml/min)

Unit

Slug

length

(cm)

Pressure

drop

(N/m2)

Reynolds

no.

Weber

no.

(Capillary

no.)*10^-3

S/V

(toluene)

(m2/m3)

1 2.3 2.3 0.2476 1640.88 114.55 0.475 3.321 6677

2 0.8 0.4 1.03333 2547.51 35.85 0.337 0.931 5503

3 0.8 0.6 0.8031 1940.72 43.43 0.0447 1.03 5492

4 1.5 0.5 1.7123 2117.17 56.46 0.095 1.68 5551

5 0.4 0.2 1.0182 1061.196 17.945 0.00833 0.4646 5506

6 0.9 0.9 0.7524 1856.5 55.675 0.0738 1.36 5606

2. Capillary internal diameter = 1mm

s. no. Water flow

rate(ml/min)

Toluene flow

rate(ml/min)

Unit

Slug

length

(cm)

Pressure

drop

(N/m2)

Reynolds

no.

Weber

no.

(Capillary

no.)*10^-3

S/V

(toluene)

(m2/m3)

1 1.00 1.00 0.3545 2271.69 56.847 0.0756 1.253 4752

2 1.50 1.50 0.3023 2582.59 79.867 0.3756 0.315 5050

3 0.50 0.50 1.0312 1679.56 36.75 0.04781 0.3186 4325

4 0.75 0.75 0.4958 2078.87 43.935 0.0678 0.1875 4550

5 0.30 0.60 1.4697 1567.15 90.195 0.08156 0.1325 4223

6 0.30 0.90 0.5778 1842.18 19.65 0.561 0.2386 4435

7 0.30 1.20 0.5117 2031.27 53.49 0.3128 0.3175 4545

8 0.50 1.50 0.4875 2261.46 48.28 0.1561 1.6981 4750

22

3. Capillary internal diameter = 0.5mm

s. no. Water flow

rate(ml/min)

Toluene flow

rate(ml/min)

Unit

Slug

length

(cm)

Pressure

drop

(N/m2)

Reynolds

no.

Weber

no.

(Capillary

no.)*10^-3

S/V

(toluene)

(m2/m3)

1 0.50 0.50 0.1782 1672.515 5.2019 0.0943 1.808 9970

2 0.30 0.30 0.2323 1470.595 29.277 0.0338 1.1574 9943

3 0.40 0.40 0.1966 2018.101 78.47 0.0588 0.7506 10157

4 0.60 0.60 0.1643 1247.099 57.135 0.1368 2.3957 11263

5 0.40 0.60 0.2725 2400.667 52.12 0.092 0.1325 9420

6 0.40 0.80 0.2543 2823.835 58.88 0.132 0.2386 9530

7 0.60 0.80 0.1952 2436.292 67.28 0.182 0.3175 10700

8 0.60 0.90 0.1772 2720.781 74.84 0.208 1.6981 10100

23

Sample Calculation:

Flow rate of toluene = 0.6 ml/min.

Flow rate of water = 0.3 ml/min.

Slug length of toluene(Ld) = 0.8896cm

Slug length of water(Lc) = 0.587cm

Unit slug length(Lu) = 1.4697cm

Contact angle() = 45

Capillary i.d. = 1mm

r = radius of slug = 0.5mm

Surface area = S = 201 + 201Ld

24

Volume = 01Ld

S/V for toluene = 4223 m2/m3

P(slug flow) = P(frictional) + P(interfacial)

= Pfr,c + Pfr,d + PI

Pfr,d = 45678

9:

Pfr,c = 45;(

25

The capillary no. is very low, thus interfacial force is predominant over viscous force.From the

results we find that the slug length is the function of slug velocity. For weber no. greater than 1,

the flow becomes annular and parallel flow. Annular and parallel flows are easily destabilized

by changing flow rates and volumetric flow ratios. Slug and drop flows are easily controllable.

The interfacial pressure drop is calculated at constant contact angle. The superficial velocity is

used to calculate frictional pressure drop. The receding & advancing contact angles can only be

assumed equal at very low velocities. The difference between them increases with the linear

velocity.

26

References

1. G.M.Whitesides. The origins and the future of microfluidics, Nature, Vol. 442, 2006.

2. M. N. Kashid, Y. M. Harshe, and D. W. Agar. Liquid-Liquid slug flow in a capillary: An alternative to suspended drop or film contactors Ind. Eng. Chem. Res.,Vol. 46, pp. 8420-8430, 2007.

3. M. N. Kashid and David W. Agar Hydrodynamics of liquidliquid slug flow capillary microreactor: Flow regimes, slug size and pressure drop Chemical Engineering Journal, pp. 113, 2007.

4. Madhvanand N. Kashid and Lioubov Kiwi-Minsker. Microstructured Reactors for Multiphase Reactions: State of the Art, Ind. Eng. Chem. Res., Vol. 48, pp. 64656485, 2009.

5. Rahul Antony, M.S. Giri Nandagopal, Nidhin Sreekumar, S. Rangabhashiyam and N. Selvaraju. Liquid-liquid Slug Flow in a Microchannel Reactor and its Mass Transfer Properties - A Review, Bulletin of Chemical Reaction Engineering & Catalysis,

pp.207-223, 2014. 6. J. R. Burns and C. Ramshaw. The intensification of rapid reactions in multiphase

systems using slug flow in capillaries Lab on a Chip, Vol. 1, pp. 1015, 2001. 7. Anne-Laure Dessimoz, Laurent Cavin, Albert Renken and Lioubov Kiwi-Minsker.

Liquidliquid two-phase flow patterns and mass transfer characteristics in rectangular Glass microreactors, Chemical Engineering Science, Vol. 63, pp. 4035 4044, 2008.

8. N. Di Miceli Raimondi, L.Prat, C.Gourdon and J.Tasselli. Experiments of mass transfer with liquidliquid slug flow in square microchannels, Chemical Engineering Science, Vol. 105, pp. 169178, 2014.

9. Bujian Xu, Wangfeng Cai, Xiaolei Liu and Xubin Zhang. Experiments of mass transfer with liquidliquid slug flow in square microchannels, Chemical Engineering Science, Vol. 105, pp. 169178, 2014.

10. Mayur Darekar, Nirvik Sen, K.K. Singh, S. Mukhopadhyay, K.T. Shenoy and S.K. Ghosh. Liquidliquid extraction in microchannels with ZincD2EHPA system, Hydrometallurgy pp. 144145, 2014.

27

11. Dimitrios Tsaoulidis and Panagiota Angeli. Effect of channel size on mass transfer during liquidliquid plug flow in small scale extractors, Chemical Engineering Journal Vol. 262, pp. 785793, 2015.

12. Mohamed Mansour, Akimaro Kawahara and Michio Sadatomi. Numerical Investigation of Two-Phase Flow through a T-Junction Microchannel Reactor

Journal of Environmental Science and Engineering, pp. 42-54, 2014. 13. Piotr Garstecki, Michael J. Fuerstman, Howard A. Stone and George M. Whitesides.

Formation of droplets and bubbles in a microfluidic T-junctionscaling and mechanism of break-up, Lab Chip, Vol. 6, pp. 437446, 2006.

14. Hemant B. Mehta and Jyotirmayi Banerjee. CFD Analysis of the Taylor slug flow in a microchannel under microgravity condition using VOF Method, International Conference on Fluid Mechanics and Fluid Power, 2010.