report

Drop Formation in Liquid-Liquid System
A Masters Project Report submitted to ENSCCF, France in partial fulfillment
of the requirement for the award of the degree of
MASTERS OF ENGINEERING
In
Chemical Engineering
Submitted by
ChaitanyaKalyan
Ecole Nationale Superieur de Chimie de Clermont-
Ferrand,France
Under the guidance of
SUPERVISOR CO-GUIDE
Mr. Nirvik Sen,
SO/D, ChED
Chemical Engineering Division
Bhabha Atomic Research Centre
nirvik@barc.gov.in
SUPERVISOR GUIDE
Dr.K.K Singh,
SO/F, ChED
Chemical Engineering Division
Bhabha Atomic Research Centre

ACKNOWLEDGEMENT
I am extremely grateful to my Project Guide Dr. K. K. Singh, and Co-Guide Shri. Nirvik
Sen for their valuable guidance, pain taking effort, constant encouragement and inspiration
during each and every step of my project work. In spite of their extremely busy schedule, I
have always found them accessible for suggestions and discussions.
I would like to thank Dr. K.T. Shenoy, Head, Chemical Engineering Division,
BARC for giving me the opportunity to carry out my project work at BARC and for
providing the necessary experimental facilities during the course of this training.
I would like to thank all the Staff of Process Engineering Section, in Chemical
Engineering Division for their appreciation and support.

CONTENTS
1. Introduction.
2. Bibliography.
3. Drop formation in phase system used in nuclear field.
4. Drop formation in basic phase system.
5. Conclusion.

INTRODUCTION
The Bhabha Atomic Research Centre (BARC) is India's premier nuclear research facility
based in Trombay, Mumbai. BARC is a multi-disciplinary research centre with extensive
infrastructure for advanced research and development covering the entire spectrum of nuclear
science, engineering and related areas.
BARC's core mandate is to sustain peaceful applications of nuclear energy, primarily for
power generation. It manages all facets of nuclear power generation, from theoretical design
of reactors, computerised modelling and simulation, risk analysis, development and testing of
new reactor fuel materials, etc. It also conducts research in spent fuel processing, and safe
disposal of nuclear waste. Its other research focus areas are applications for isotopes in
industries, medicine, agriculture, etc. BARC operates a number of research reactors across
the country.
The first reactors at BARC and its affiliated power generation centres were imported from the
west. India's first power reactors, installed at the Tarapur Atomic Power Station were from
the United States.
The primary importance of BARC is as a research centre. The BARC and the Indian
government has consistently maintained that the reactors are used for this purpose only:
Apsara (1956; named by the then Prime Minister of India, Jawaharlal Nehru when he likened
the blue Cerenkov radiation to the beauty of the Apsaras (Indra's court
dancers),CIRUS (1960; the "Canada-India Reactor" with assistance from Canada), the now-
defunct ZERLINA (1961; Zero Energy Reactor for Lattice Investigations and Neutron
Assay), Purnima I (1972), Purnima II (1984), Dhruva (1985), Purnima III (1990),
and KAMINI.
1

BIBLIOGRAPHY
2.1 INTRODUCTION
Drop formation in sieve plates is a complex phenomenon, which depends on the flow
velocity in the holes, physical properties of the liquid phases like surface tension and density
difference, material properties of the sieve plate such as the wetting properties and surface
roughness, size and structure of the hole, distance between the holes and alignment of holes
on the sieve plate. The formation of drop is necessary for the solvent extraction. The small
droplets are usually desired to increase the interfacial area available for mass transfer and to
maximize the process efficiency. The formation of spherical drops depends on size and shape
of holes.
There has been significant work on drop formation form single nozzles throughout the last
century (Hayworth et al., Scheele and Meister). However similar work on drop formation
right at the hole is limited. Soleymani et. al., (2012) described the different stages of drop
formation in a sieve hole. The formation of drop in a plate can be described in four main
periods namely, separation, spreading, growth and necking periods. The period of separation
starts just after detachment of drop. During this stage the height of the drop decreases and it
starts spreading. During the stage of spreading, the base of drop starts spreading along the
plate. At the end of this period, the base of the drop reaches to its maximum value. Just after
the end of this period , in the beginning of the growth period the drop base starts decreasing.
Though the height of the drop increases during this period, its maximum width doesn’t
change considerably. At the stage of necking, the drop becomes elongated and expands
continuously while moving upwards. During this last stage, the neck formation begins and at
the end of this stage the drop detaches.
2.2 EXPERIMENTAL SET-UP
The schematic diagram of the setup is shown in Figure 2.1. The primary set up consisted of
acrylic column (optically transparent) with provision of incorporating a SS plate. Different
SS plates were used whereby effect of hole diameter and pitch was observed. The holes were
made by punching into the metal sheets. The column was initially filled with the continuous
2

(heavier) phase. and the dispersed (lighter) phase was pumped in through two high-precision
positive displacement syringe pumps (0-10ml/min flow rate range). The phases were pre
equilibrated which ensured that solubility effects of one into another will not be significant.
Two pumps were used and flow was provided to the column through wither side at equal
flow rates. Infact effect of asymmetric flow rates was also studied for one phase system. The
dispersed phase issues out of the holes as drops/ jets depending on the operating condition
and the same was captured using a high speed imaging system at a frequency of up to 1660
frames per second. Proper illumination so as to ensure images of good contrast was ensured.
A computer was connected to the imaging system to save the images. Illumination for
imaging was provided by a light source. Different phase systems were used in the above
experiments so as to observe the effect of physical properties on the drop formation process
at the sieve holes.
Fig 2.1 Schematic Diagram
The different sieve plates were used to study the drop formation. The plates were made of
stainless steel of 1 mm of thickness. Different diameter and pitch plates were made for this
study. The diameter of 1,2,3,4 mm and pitch of double the diameter were manufactured. For
study of different pitch, plates were made of diameter of 3 mm with pitch of 4,6,8,10,13 mm.
Each plates were consist of 3 holes. A plate of poly propylene was made with diameter of 3
mm and pitch of 6 mm with 3 holes to study the effect of plate material on drop formation.
The phase systems used in the experiments were water-butanol, water-toluene,water-butyl
acetate and water-TBP-nitric acid. The phase systems (water-butyl acetate and water-butanol)
has got medium interfacial tension while the water toluene has got high interfacial tension
and the water-TBP-nitric acid has got lowest interfacial tension . The physical properties of
the systems are given in Table 2.1,
ORGANIC
PHASE
FEED
PUMP
CAMERA
AQUEOUS
PHASE
LIGHT
SOURCE
3

Table 2.1 Physical properties of different phase system.
Phase System Density
(kg/m3
)
Interfacial
tension
(mN/m)
1.
Aqueous Water 1000
34.7
Organic Toluene 846.3
2.
Aqueous Water 1000
1.47
Organic Butanol 893
3.
Aqueous Water 1000
14.7
Organic Butyl acetate 789
4.
Aqueous 3N Nitric acid 1128 28.7
Organic TBP (30%)-
dodecane
816.69
2.3 UNIQUENESS OF THE WORK
The works carried out in earlier attempts were restricted to nozzle and single sieve hole. The
significant development in the study of drop formation in multiple sieve holes was lacking.
Here, we carried out the study of drop formation in 3 holes on SS plate. The drop diameter,
height of drop detachment, time of drop detachment were studied by varying the hole
diameter, pitch, height between plates and the material of plates at different hole velocity.
The practical use of multiple sieve holes can be observed in the nuclear industries. This study
enables us to realise the practical phenomena carried out in nuclear and related industries on
day to day basis for the solvent extraction and waste extraction. However, the study can be
useful for defining the different correlation for multiple sieve holes in different stages of drop
formation along with the explanation in jetting regime.
4

DROP FORMATION IN PHASE SYSTEM USED IN NUCLEAR FIELD
3.1 TBP-NITRIC ACID-WATER SYSTEM
Many industrial and environmental processes involve the impact of drops on solid surface
like ink jet printing, pesticides spraying, spray cooling, oil atomizing in fuel burners, drop
wise condensation, emulation formation and many more. In most of the applications, uniform
size distribution and fast formation rate of droplets are required for yielding predictable high
quality products, increasing the process efficiency and reducing operational time. This study
on TBP-Nitric acid water system can be helpful in developing ways to maximize mass
transfer in nuclear industries.
3.2 OBSERVATION
Fig 3.1: Fig 3.2:
5
3
3.5
4
4.5
5
5.5
0 0.02 0.04 0.06
d[mm]
U [m/sec]
pitch_13 mm
pitch_10 mm
pitch_4 mm
pitch_6 mm
1.5
2
2.5
3
3.5
4
4.5
5
5.5
0.001 0.01 0.1 1
d[mm]
U [m/sec]
d_1 mm
d_2 mm
d_3 mm
d_4 mm
Effect of hole flow velocity on
drop diameter for different
pitch.
hole diameter.

Fig 3.3: Fig 3.4:
Fig 3.5: Fig 3.6:
Fig 3.7: Fig 3.8:
0
5
10
15
20
25
0.001 0.01 0.1 1
h[mm]
U [m/sec]
d_1 mm
d_2 mm
d_3 mm
d_4 mm
0
1
2
3
4
5
6
7
8
0 0.01 0.02 0.03 0.04 0.05
h[mm]
U [m/sec]
pitch_13 mm
pitch_10 mm
pitch_4 mm
pitch_6 mm
0
5
10
15
20
25
30
0.001 0.01 0.1 1
time[sec]
U [m/sec]
d_1 mm
d_2 mm
d_ 3 mm
d_4 mm
0
5
10
15
20
25
30
35
40
0 0.01 0.02 0.03 0.04 0.05
time[sec]
U [m/sec]
pitch_4 mm
pitch_6 mm
pitch_10 mm
pitch_ 13 mm
0
1
2
3
4
5
6
7
8
9
10
0 0.02 0.04 0.06
h[mm]
U [mm]
1st
2nd
0
1
2
3
4
5
6
7
8
9
10
0 0.02 0.04 0.06
d[mm]
U [m/sec]
1st
2nd
Effect of hole flow velocity
on drop detachment height for
different hole diameter.
different pitch.
on drop detachment time for
drop detachment height for
different pitch.
Different attempts to check
repeatability.
repeatability in diameter 3mm
and pitch 10 mm.
repeatability in diameter 3mm
and pitch 10 mm.
6

Fig 3.9: Fig 3.10:
Fig 3.11: Fig 3.12:
Fig 3.13: Fig 3.14:
0
5
10
15
20
25
30
35
0 0.01 0.02 0.03
time[sec]
U [m/sec]
pitch_6 mm
pitch_10 mm
pitch_ 13 mm
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0.01 0.1 1
d[mm]
U [m/sec]
h_0 mm (single plate)
h_14 mm
h_28 mm
2.1
2.15
2.2
2.25
2.3
2.35
2.4
2.45
2.5
2.55
0.01 0.1 1
h[mm]
U [m/sec]
h_0 mm (single plate)
h_14 mm
0
2
4
6
8
10
12
14
16
18
0 0.1 0.2 0.3 0.4 0.5
time[sec]
U [m/sec]
h_28 mm
h_14 mm
h_0 mm
1.5
2
2.5
3
3.5
4
0.15 0.2 0.25 0.3 0.35 0.4
d[mm]
U [m/sec]
1st
2nd
0
0.5
1
1.5
2
2.5
3
3.5
0.15 0.2 0.25 0.3 0.35
h[mm]
U [m/sec]
1st
2nd
on delay time in different
pitch.
drop diameter in different plate
height.
on drop detachment height in
different plate height.
drop detachment time in
different plate height.
on drop diameter in
asymmetric flow.
on drop detachment height in
asymmetric flow.
7

The results were plotted for different parameters such as drop diameter, height of drop
detachment, time of drop detachment against the hole flow velocity. The graphs for
repeatability and the flow asymmetry was also plotted against the hole flow velocity. Drop
diameter increases with increase in flow velocity whereas the height of drop detachment and
time of drop detachment decreases with an increase in hole velocity. The drop diameter
increases with hole diameter whereas achieves an maxima with variation of pitch. The trend
observed in drop diameter with variation in pitch is that at low pitch the drop diameter is less
and as the pitch increases the drop diameter increases and reaches a maxima and then reduces
as pitch is further increased. The height of drop detachment increases with hole diameter and
follows the same trend as in drop diameter for the variation in pitch. The time of drop
detachment decreases with increase in hole diameter and pitch. The graph of repeatability
shows constant variation of drop diameter and height of detachment with hole flow velocity
as it was in the first trial.
An interesting observation which was later found to be specific to TBP/Nitric acid system
was that the drop formation process was intermittent in nature for larger values of pitch and
especially so for low flow velocities. The delay increased with increase in pitch.
In a real life extraction column there will be multiple plates one above the other. This may
significantly affect the drop formation process and have a telling on the final drop diameter.
This effect was also studied in our work where another plate was put over the first
maintaining different gap between the plates. It was observed that the gap between the plates
was 28 mm there was insignificant deviation between the drop diameter but as the gap was
further reduced to 14 mm the drops formed were significantly larger. However a significant
change with regard to the drop detachment height was not observed with difference in gap
between plates.
Effect of flow asymmetry was also studied in this work and as is evident from the plots there
is hardly any of flow asymmetry on drop diameter and drop detachment height.
Fig 3.15: Drop
formation at
high flow
rate(10 ml/min).
Fig 3.16: Drop
formation at
low flow rate(1
ml/min).
Fig 3.17: Drop
formation at
intermediate
flow rate(5
ml/min).
8

3.3 CONCLUSION
The drop diameter is seen to increase with increase in flow velocity. In the drop formation
regime this is because of increased flow of the dispersed phase into the drop during the
necking regime. Height and time of drop detachment was found to decrease with flow
velocity. These observation is consistent with earlier findings (Scheele and Meister, 1968).
Drop diameter increase with increase in hole diameter (for same flow velocity). This is
because at same flow velocity as the diameter increases more and more of the dispersed
phase will accumulate in to the drop leading to larger drops. The percentage increase in drop
diameter was found to be 0.36% for at lower flow rate while at higher flow rates it was
around 0.86% as the hole diameter was varied form 1- 4 mm. However it was observed that
for 1 mm hole diameter there is a sudden fall in drop diameter after which it increase once
again. This is attributed to the transition to jetting regime for the 1 mm hole diameter.
With increase in pitch the dispersed phase will spread to a greater extent below the plate.
Hence there will be a competition between the amount of dispersed phase that spreads below
the plate and that which will move out through the hole (in form of drop). This competition is
also represented in form of prevalence of the phenomena of intermittent drop formation at
higher values of pitch. As the pitch was increased form 4 mm to 6 mm the drop detachment
time decreased drastically due to the initiation of intermittent drop formation phenomena at 6
mm pitch. This will lead to large amount of dispersed phase gushing into the forming drops
(at those instances at which the drops are forming) so as to maintain the volumetric flow. As
pitch is increased beyond 6 mm the time of drop detachment is not changing to a large extent
as is evident form the plots above. However as pitch goes on increasing the volume of
dispersed phase that is contributing to spreading below the plate will dominate and drop
formation will be subdued to an extent leading to smaller drops. It is to be kept in mind that
intermittent flow was obtained for all values of pitch greater than 6 mm. Infact it is also
shown that as plates with higher pitch is being used the delay time (defined as time gap
between two consecutive drop formation events) increases. This is because as the pitch is
increasing the phenomena of spreading dominants the drop formation process itself a fact that
is responsible for the observed behavior of the drop diameter with pitch.
When drops were forming at holes in a single plate the drops were forming and detaching
freely. As the dispersed phase forms and move up there will be certain circulatory currents
induced in the continuous phase. The creation of these currents are because of the constancy
of velocity and shear stress at the fluid-fluid interface. However if an additional plate is put
on top these circulatory flow patterns will change. The flow will be severely restricted asn the
severity of restriction will increase with a decrease in gap between the plates. This is translate
into an increase in drop diameter as the gap between the plates is reduced to 14 mm. Infact it
is also seen that at a gap between the plate of 28 mm the drop diameters are essentially the
same as that obtained for the single plate. Hence for a sieve plate column where the gap is
maintained at 50.8 mm the drop diameters is expected not be influenced by presence of
another plate.
9

DROP FORMATION IN BASIC PHASE SYSTEMS
4.1 OBJECTIVE
The different basic phase systems such as water-butanol, water-butyl acetate and water-
toluene were studied. These systems were considered because these are recommended liquid-
liquid systems for benchmarking solvent extraction devices. These systems among them
covers a wide range of interfacial tension. Sieve plate have been used a dispersal device in
extraction equipment for a long time but a fundamental study into drop formation for plates
with multiple sieve holes (at location of the plate) is scarce in open literature. The
experiments were carried out to elucidate effect of flow velocity, diameter, pitch on drop
formation phenomena. Effect of plate material on drop formation process was also studied for
the butanol water system.
4.2 BUTANOL-WATER SYSTEM
The butanol-water system is having low interfacial tension in comparison to other systems.
The experiments were carried out with varying the flow rate from both the pumps but equal
flow rates were provided from both pumps for each reading. The variation in different
physical parameters can be observed in the obtained graphs.
4.2.1 OBSERVATION
Fig 4.18: Fig 4.19:
10
0
0.5
1
1.5
2
2.5
3
3.5
0.001 0.01 0.1 1
d[mm]
U [m/sec]
d_1 mm
d_2 mm
d_3 mm
d_4 mm
0
5
10
15
20
25
30
35
0.001 0.01 0.1 1
h[mm]
U [m/sec]
d_1 mm
d_2 mm
d_3 mm
d_4 mm
on drop diameter for different
hole diameter.

Fig 4.20: Fig 4.21:
Fig 4.22 : Fig 4.23:
Fig 4.24: Fig 4.25:
2
2.2
2.4
2.6
2.8
3
3.2
0 0.02 0.04 0.06
d[mm]
U [m/sec]
pitch_4 mm
pitch_6 mm
pitch_8 mm
pitch_10 mm
pitch_13 mm
0
5
10
15
20
25
0 0.01 0.02 0.03 0.04 0.05
h[mm]
U [m/sec]
pitch_4 mm
pitch_6 mm
pitch_8 mm
pitch_10 mm
0
5
10
15
20
25
0.001 0.01 0.1 1
time[sec]
U [m/sec]
d_1 mm
d_2 mm
d_3 mm
d_4 mm
0
5
10
15
20
25
0 0.01 0.02 0.03 0.04 0.05
time[sec]
U [m/sec]
pitch_4 mm
pitch_6 mm
pitch_8 mm
pitch_10 mm
pitch_13 mm
-10
0
10
20
30
40
50
60
70
0 0.1 0.2 0.3
time[sec]
U [m/sec]
1st
2nd
0
5
10
15
20
0 0.01 0.02 0.03
time[sec]
U [m/sec]
1st
2nd
pitch.
different pitch.
drop detachment time for
different pitch.
different hole diameter in
verifying the experiment.
drop detachment time for
different attempts on poly
propylene plate.
11

Fig 4.26:
The graphs were plotted for different physical parameters with variation in hole flow
velocity. Drop diameter and drop detachment height increased with increase in flow velocity
while time of drop detachment decreased. The drop diameter and drop detachment height
increased with increase in hole diameter. In case of varying pitch, drop detachment height
shows same trend as observed for TBP nitric acid system where at low value of pitch both are
having lower values whereas it increases significantly for moderate values of pitch and again
drop down for higher values. However specially in the jetting regime drop diameter
decreased with increase in pitch. The drop detachment time decreases with increase in hole
diameter as well as increase in pitch. Authenticity of the experimental results were checked
by performing a repeatability check for one plate geometry of diameter of 3 mm and pitch of
10 mm, results of which are presented above. It is seen that the results obtained are indeed
close to each other.
12
0
0.5
1
1.5
2
2.5
3
3.5
0 0.1 0.2 0.3
d[mm]
U [m/sec]
pp 1
pp 2
attempts on poly propylene
plate.
Fig 4.27 : Jet
formation at high
flow rate (individual
flow)(10 ml/min).
Fig 4.28: Jet
formation at high
flow rate in poly
propylene plate(10
ml/min).
Fig 4.29: Drop
formation at low
flow rate(1
ml/min).
Fig 4.30: Jet
formation at high
flow rate(merging at
certain height)(10
ml/min).

4.2.2 CONCLUSION
The observations listed in the previous section are a result of the low interfacial tension phase
considered and the geometric properties of the plates studied. The most important observation
was formation of jet at high flow rates in all the plates studied. The phenomena of jetting was
more pronounced in hole of smaller diameter and smaller pitch where three different strands
were projecting outwards and meeting at certain distance to form big drops. The jets forming
in holes with larger diameter and pitch were straight and move upward individually. The jets
were formed at flow velocity of 0.04263, 0.01061, 0.00478, 0.00265 m/sec in diameter
1,2,3,4 mm respectively. The jets disintegrated into drops at a certain height and gave rise to
three individual trains of drops which travelled separately to the interface of continuous phase
and dispersed phase. The sudden jump in the plots signified transitions to jetting regime. The
jump describes the high value of drop detachment height and drop detachment time on other
hand it was responsible for the lower drop diameter. In the jetting regime it is seen that the
drop diameter keeps on increasing with increase in hole diameter for a constant flow velocity.
This is attributed to the fact that as hole diameter is increasing for a constant hole velocity the
initial diameter of the jet is more which will lead to drops of larger volume. Drop volume in
jetting regime will depend on the thickness of the jet and the length in between the dominant
nodes. Hence for a given set of disturbance larger the initial diameter of the jet larger will be
the drops formed due to it’s disintegration. Drop diameter is decreasing with increase in
pitch. This is attributed to the fact that as the pitch is more the dispersed phase will travel
larger distances between the holes along the underside of the plate and tends to spread to an
extent. This spreading will lead to velocity components will increase in a way the initial
disturbances in the jet and will lead to shorter wave lengths (or smaller drops). Additionally it
is also seen that transition to jetting is the highest for the plate with the largest pitch. This is
due to the fact that as pitch is more the spreading is more which means significant dispersed
phase volume will not be available at the location of the hole to form a sustained jet at low
velocities. Height of drop detachment is increases with increase in flow velocity as is
observed for jetting regime (Scheele and Meister, 1968). In jetting regime the drop
detachment height will be more for larger drops. This is what is observed for the above
experiments also. The most interesting phenomena took place in poly propylene plate where
at higher flow rates all the three holes participated together to form a tripod like projection.
The phenomena was verified with the repetition of the experiment. The projection can be
explained by a combination of lower interfacial tension force and wetting of the PP plate by
the organic butanol phase. The superior wettability of the PP plate by the organic phase will
lead to a spreading of the organic phase along the plate while the lower interfacial tension
will not allow drop formation and the entire dispersed phase will tend to move as a
cylinder/jet. Now that these jets are pulled towards the plate and more so towards one another
thee otherwise free standing jets merge and a tripod formation is achieved.
13

4.3 TOLUENE-WATER SYSTEM
The toluene-water system is having highest interfacial tension among all the phases studied.
The jetting phenomena was absent in this system and drop formation was observed
throughout the different flow rates because of higher interfacial tension forces. The phase
system considered was thoroughly pre equilibrated so as to mitigate any solubility effect.
4.3.1 OBSERVATION
Fig 4.31: Fig 4.32:
Fig 4.33: Fig 4.34:
14
0
2
4
6
8
10
12
0.001 0.01 0.1 1
h[mm]
U [m/sec]
d_1 mm
d_2 mm
d_3 mm
d_4 mm
4
4.5
5
5.5
6
6.5
7
0.001 0.01 0.1 1
d[mm]
U [m/sec]
d_1 mm
d_2 mm
d_3 mm
d_4 mm
0
1
2
3
4
5
6
7
8
9
10
0 0.01 0.02 0.03 0.04 0.05
h[mm]
U [m/sec]
pitch_4 mm
pitch_6 mm
pitch_8 mm
pitch_10 mm
pitch_13 mm 0
1
2
3
4
5
6
7
8
0 0.01 0.02 0.03 0.04 0.05
d[mm]
U [m/sec]
pitch_4 mm
pitch_6 mm
pitch_8 mm
pitch_10 mm
hole diameter.
on drop detachment height
for different pitch.
on drop diameter for
different pitch.

Fig 4.35: Fig 4.36:
The different graphs were plotted with the variation in hole flow velocity for different
parameters. The drop diameter and drop detachment height increased with the increase in
hole diameter. The drop detachment height is lower for the plates having smaller pitch,
whereas it increased at intermediate pitch and again decreased for high pitch. However the
drop diameter decreased with increase in pitch reaches a minimum and then increased again.
The drop detachment time decreased with increase in hole diameter, interestingly there was
no such variation noted in case of varying pitch.
4.3.2 CONCLUSION
The absence of jetting regime was one of the significant observation for this system, which
was responsible for the constant drop formation in all the plates at all the different flow rates
0
20
40
60
80
100
120
140
160
180
0.001 0.01 0.1 1
time[sec]
U [m/sec]
d_1 mm
d_2 mm
d_3 mm
d_4 mm
0
20
40
60
80
100
120
140
160
180
200
0 0.02 0.04 0.06
time[sec]
U [m/sec]
pitch_4 mm
pitch_6 mm
pitch_8 mm
pitch_10 mm
pitch_13 mm
different pitch.
Fig 4.37: Drop
formation at low flow
rate(1 ml/min).
Fig 4.38: Drop
formation at high flow
rate(10 ml/min).
Fig 4.39: Drop
formation at
intermediate flow
rate(5 ml/min).
15

primary because of higher interfacial tension. The high interfacial tension also led to perfect
spherical drops observed in this system. As the drop formation regime was observed increase
in velocity increased drop diameter due to accumulation of more and more of the dispersed
phase in the drop during the necking period of the drop formation process. Similar to that
observed for TBP-Nitric acid system larger drops were formed as hole diameter increased
due to the fact that at same flow velocity more volume of the dispersed phase will go through
larger diameter holes.
As the more and more accumulation took place beneath the hole the tendency for forming the
drop increased and that is why drop detachment height increased with increase in hole
diameter. The drop detachment time decreased with decrease in hole diameter because the
spreading and accumulation of dispersed phase was fast and formation of drop was quite
rapid.
4.4 BUTYL ACETATE-WATER SYSTEM
The butyl acetate water system was having interfacial tension close to toluene water system,
so, the observation for both the systems were quite similar. The effect of interfacial tension
can be observed on distinguishing the continuous phase and dispersed phase when drop
formation takes place.
4.4.1 OBSERAVTION
Fig 4.40: Fig 4.41:
16
0
2
4
6
8
10
12
0.001 0.01 0.1 1
h[mm]
U [m/sec]
d_1 mm
d_2 mm
d_3 mm
d_4 mm
3
3.5
4
4.5
5
5.5
6
0.001 0.01 0.1 1
d[mm]
U [m/sec]
d_1 mm
d_2 mm
d_3 mm
d_4 mm
for different hole diameter.
hole diameter.

Fig 4.42: Fig 4.42:
Fig 4.43: Fig 4.44:
The significance of different physical parameters can be studied with respect to variation in
hole flow velocity. The graph showed common behaviour as it was observed in toluene water
system. The increase in drop diameter and height of drop detachment along with increase in
hole diameter can be seen. In case of increasing pitch both the parameters shown maxima
value at intermediate values and decreased significantly after the increase. The time of drop
detachment decreased with decrease in hole diameter and same observation was noted in
varying pitch as it was in toluene water system.
17
4
4.5
5
5.5
6
6.5
7
7.5
8
8.5
0 0.01 0.02 0.03 0.04 0.05
h[mm]
U [m/sec]
pitch_4 mm
pitch_6 mm
pitch_8 mm
pitch_10 mm
pitch_13 mm 4
4.2
4.4
4.6
4.8
5
5.2
5.4
0 0.01 0.02 0.03 0.04 0.05
d[mm]
U [m/sec]
pitch_4 mm
pitch_6 mm
pitch_8 mm
pitch_10 mm
pitch_13 mm
0
50
100
150
200
250
0.001 0.01 0.1 1
time[sec]
U [m/sec]
d_1 mm
d_2 mm
d_3 mm
d_4 mm
0
20
40
60
80
100
120
0 0.02 0.04 0.06
time[sec]
U [m/sec]
pitch_4 mm
pitch_6 mm
pitch_8 mm
pitch_10 mm
pitch_13 mm
on drop detachment time
for different hole diameter.
for different pitch.
pitch.
different pitch.

4.4.2 CONCLUSION
The increase in drop diameter and drop detachment height along the increase in hole flow
velocity for increasing hole diameter can be observed in this system. This is so because the
high flow velocity was responsible for more organic phase discharge under the holes, hence
more accumulation took place and it increased the probability of formation of drops. The
high interfacial tension also led to perfect spherical drops observed in this system. As the
drop formation regime was observed increase in velocity increased drop diameter due to
accumulation of more and more of the dispersed phase in the drop during the necking period
of the drop formation process. Similar to that observed for TBP-Nitric acid system larger
drops were formed as hole diameter increased due to the fact that at same flow velocity more
volume of the dispersed phase will go through larger diameter holes. As the more and more
accumulation took place beneath the hole the tendency for forming the drop increased and
that is why drop detachment height increased with increase in hole diameter.
18
Fig 4.45: Drop formation at
low flow rate(1 ml/min).
Fig 4.46: Drop
formation at
intermediate flow rate(5
ml/min).
Fig 4.47: Drop formation
at high flow rate(10
ml/min).

CONCLUSION
5.1 FUTURE PROSPECTS OF WORK
The work carried out can be very helpful in developing different correlation in multiple sieve
hole systems. The industries mainly nuclear oriented work with multiple holes for the solvent
extraction. The extraction is a complex phenomenon where number of factor influences the
process. The development of new correlations can determine the high mass transfer rate in
the different system where drop formation plays an important role. The computational
simulation can be carried out with the help of COMSOL to study the drop formation process
in multiple sieve holes. Simulations will lead to a more fundamental understanding of the
process and how multiples sieve holes will interacts with one another and finally effect the
drop diameter.This understanding will lead to an accurate estimate of specific interfacial area
for mass transfer. The effects of various operating and design parameters on the drop
formation can be study in order to optimize the drop formation.
5.2 EXPERIENCE
The personal experience of working at BARC was one of the best experience of my life. I
enhanced my knowledge professionally and practically. The working atmosphere was
outstanding where mentors and guides were always ready to help. The
equipments,facilities,labs were well equipped where I was given ample time and support to
carry out my work. The privilege of working with such an esteem group of people was an
outstanding experience. Although I am native still the exposure of such institute was missing
from my working credentials. I am very honored to work at BARC.
19

REFERENCES
1. Hayworth, Treybal, Drop formation in two-liquid-phase systems, Ind. Eng.Chem., 43
(1950), 1174.
2. Soleymani, A., Laari, A., Turunen, I., Simulation of drop formation in a single hole in
solvent extraction using the volume-of-fluid method, Chem. Engg. Res. Des., 86 (2008), 731-
738.
3. Bernard J. Meister and George F. Scheele, Drop formation from cylindrical jets in
immiscible liquid systems.
4. Bernard J. Meister and George F. Scheele, Prediction of jet length in immiscible liquid
systems.
5. Arun Kumar and Stanley Hartland, Correlation for drop size in liquid/liquid spray
columns. 2007, 193-207.
6. John R. Richards, Antony N. Beris, Abraham M. Lenhoff, Drop formation in liquid-liquid
systems before and after jetting. 1995, 2617-2630

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