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STUDIES ON WASTE HEAT RECOVERY SYSTEM AND
DESIGN OF SHELL AND TUBE HEAT EXCHANGER
USING VISUAL BASIC
&
STUDIES ON CIRCULATING FLUIDISED BED
A PROJECT REPORT
Submitted by
SELLAVEL.E (10CHR052)
SUKE.S (10CHR056)
SUTHAKAR.V (10CHL074)
in partial fulf ilment of the requirements
for the award of the degree
of
BACHELOR OF TECHNOLOGY
IN
CHEMICAL ENGINEERING
DEPARTMENT OF CHEMICAL ENGINEERING
SCHOOL OF CHEMICAL AND FOOD SCIENCES
KONGU ENGINEERING COLLEGE
(Autonomous)
PERUNDURAI ERODE638 052
APRIL 2014
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DEPARTMENT OF CHEMICAL ENGINEERING
KONGU ENGINEERING COLLEGE
(Autonomous)
PERUNDURAI ERODE638052
APRIL 2014
BONAFIDE CERTIFICATE
This is to certify that the Project report entitled STUDIES ON WASTE HEAT
RECOVERY AND DESIGN OF SHELL AND TUBE HEAT EXCHANGER USING
VISUAL BASIC AND STUDIES ON CIRCULATING FLUIDISED BED is the
bonafied record of project work done by SELLAVEL.E (10CHR052), SUKE.S
(10CHR056), SUTHAKAR.V (10CHL074) in partial fulfilment of the requirements for
the award of the Bachelor of Technology in Chemical Engineeringof Anna university
Chennai during the year 2013 2014.
SUPERVISOR HEAD OF THE DEPARTMENT
(Signature with seal)
Date:
Submitted for the end semester viva voce examination held on___________
INTERNAL EXAMINER EXTERNAL EXAMINER
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DEPARTMENT OF CHEMICAL ENGINEERING
KONGU ENGINEERING COLLEGE
(Autonomous)
PERUNDURAI ERODE 638052
APRIL 2014
DECLARATION
We affirm that the Project Report titled STUDIES ON WASTE HEAT RECOVERY
USING AMMONIA WATER SYSTEM AND DEVELOPMENT OF VISUAL BASIC
APPLICATION FOR DESIGN OF SHELL AND TUBE HEAT EXCHANGER
STUDIESS ON CIRCULATING FLUIDISED BED being submitted in partial
fulfilment of the requirements for the award of Bachelor of Engineering is the original
work carried out by us. It has not formed the part of any other project report or dissertation
on the basis of which a degree or award was conferred on an earlier occasion on this or any
other candidate.
Date: SELLAVEL.E
(Reg.No.10CHR052)
SUKE.S(Reg.No.10CHR056)
SUTHAKAR.V
(Reg.No.10CHL074)
I certify that the declaration made by the above candidates is true to the best of my
knowledge.
Name and Signature of the Supervisor with seal
Date:
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ABSTRACT
STUDIES ON WASTE HEAT RECOVERY AND DESIGN OF SHELL
AND TUBE HEAT EXCHANGER USING VISUAL BASIC
A combined refrigeration cycle uses ammonia and water mixture as a working fluid
to produce power and refrigeration in the same cycle. The parameters are varied to
influence the cycle are heat source temperature, boiler pressure, ammonia mass fraction,
ratio of working and heating fluid flow rates. This cycle produces the power of about 88.4
KW. The material and the energy balances of the individual equipment is done for this
cycle. Using the values obtained from above energy balances, the design of shell and tube
heat exchanger is made by the application software Visual Basic.
STUDIES ON CIRCULATING FLUIDISED BED
The circulating fluidised bed is cylindrical vessel with conical bottom is used as a
reactor with inlet from bottom of the vessel. Dead zones are formed around the cylindrical
wall of the reactor, due to this catalyst were lumped in.The lump of catalyst produces a
sudden rise in temperature, the spiral type agitator with one end suspended and other free
end will be suitable to overcome this problem. Lab scale experimental set up was
fabricated. The hydrodynamic study was carried out using the starch solution and bio
catalyst (ragi).The effect of flow rate, fluid properties such as viscosity, density and the
solid loading on the solid circulation rate and the pressure drop were studied was made and
the graphs were plotted. From results that the circulating fluidized bed with agitator gives
better performance.
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ACKNOWLEDGEMENT
First of all we thank the almighty, who is behind all our endeavours and blessed us
in completing the project successfully. We thank our beloved correspondent
Thiru. V.K. Muthuswamy, B.A., B.L., and all the members of Kongu Vellalar Institute
of Technology Trust at this high time for providing us with plethora of facilities to
complete our project successfully.
We take it a privilege to express our profound thanks to our beloved principal
Prof. S.Kuppuswami B.E., M.Sc., Dr.Ing (France) who has been a bastion of moral
strength and a source of incessant encouragement to us.
We express our sincere thanks to Head of the Chemical Engineering department
Dr.K.Saravanan, M.Tech., Ph.D., (Tech) for his valuable guidance and suggestion.
We also take this opportunity to express a deep sense of gratitude to our project
guide DR.K.Kannan, M.Tech., Ph.D., Associate professor for his exemplary guidance,monitoring and constant encouragement throughout the course of this project.
We take immense pleasure to express our heartfelt thanks to our beloved project
coordinator Dr.V.Chitra Devi, M.Tech., Ph.D.,Associate Professor for his valuable and
constant support provided all through the course of the project.
We also thank the non-teaching staff members of Chemical Engineering
Department and all our fellow students who stood with us to complete our project
successfully. We also extend our warm thanks to our beloved parents.
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TABLE OF CONTENTS
CHAPTER No. TITLE PAGE No.
ABSTRACT iv
LIST OF FIGURES viii
LIST OF SYMBOLS ix
STUDIES ON WASTE HEAT RECOVERY
AND DESIGN OF SHELL AND TUBE
HEAT EXCHANGER USING VISUALBASIC
1 INTRODUCTION 2
2 LITERATURE REVIEW 3
3 SYSTEM DESCRIPTION 4
4 MASS BALANCES 6
4.1 FLASH SEPARATOR 6
5 ENERGY BALANCES 8
5.1 FLASH SEPARATOR 8
5.2 SUPER HEATER 9
5.3 TURBINE 10
5.4 ABSORBER 11
5.5 REFRIGERATION 12
5.6 HEAT EXCHANGER 12
5.7 VAPOURISER 14
6 DESIGN OF SHELL AND TUBE HEAT
EXCHANGER
15
6.1 VISUAL BASIC CODING 21
7 CONCLUSION 29
REFERENCES 30
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CHAPTER No. TITLE PAGE No.
STUDIES ON CIRCULATING
FLUIDISED BED
1 INTRODUCTION 32
2 LITERATURE REVIEW 34
3 MATERIALS AND METHODS 35
3.1 MATERIALS USED 35
3.2 METHODS USED 36
4 EXPERIMENTAL SET UP 37
4.1 EXPERIMENTAL PROCEDURE 37
5 RESULTS AND DISCUSSIONS 38
6 CONCLUSION 44
REFERENCES 45
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LIST OF FIGURES
FIGURE No. TITLE PAGE No.
STUDIES ON WASTE HEAT RECOVERY AND
DESIGN OF SHELL AND TUBE HEAT
EXCHANGER USING VISUAL BASIC
3.1 FLOW SHEET FOR AMMONIA WATER SYSTEM 5
5.1 FLASH SEPERATOR 7
5.2 SUPER HEATER 8
5.3 TURBINE 95.4 ABSORBER 10
5.5 REFRIGERATION 11
5.6 HEAT EXCHANGER 11
5.7 VAPOURISER 13
6.1 SHELL AND TUBE HEAT EXCHANGER 26
6.2 SHELL AND TUBE HEAT EXCHANGER APPLICATION 27
STUDIES ON CIRCULATING FLUIDISED
BED
3.1 SPIRAL AGITATOR 35
4.1 EXPERIMENTAL SETUP 37
5.1 CONCENTRATION (gm/lit) Vs. FLOW RATE
(ml/sec)(without stirrer)
40
5.2 CONCENTRATION (gm/lit) Vs. FLOW RATE (ml/sec)
(with stirrer)
42
5.3 PRESSURE DROP (N/m2) Vs. FLOW RATE (ml/sec) 42
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LIST OF SYMBOLS
S.
No
Unit
Operations
Inlet
Tempera
-ture
Outlet
Temperature
Mass
in
Mass
out
Inlet
energy
Outlet
energy
Energy
added
Work
done
1Flash
Separator
2
Super
Heater
3Turbine
4Absorber
5Refrigeration
6Heat
exchanger
7 Vaporiser
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STUDIES ON WASTE HEAT RECOVERY AND DESIGN OF
SHELL AND TUBE HEAT EXCHANGER USING
VISUAL BASIC
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CHAPTER 1
INTRODUCTION
Multi-component working fluids in power cycles exhibit variable boiling
temperatures during the boiling process which make them suitable for a sensible heat
source. The temperature difference between the heat source and the working fluid remains
small to allow for a good thermal match between the source and working fluid, such that
less irreversibility results during the heat addition process.
A Novel ammoniawater binary mixture thermodynamic cycle capable of
producing both power and refrigeration has been proposed by Go swami. An ammonia
water mixture is used as it exhibits desirable thermodynamic properties in terms of a large
heat capacity. Ammonia is relatively inexpensive, can accommodate system designmodifications well and separates easily from internal lubricating oils.
Ammonia is also environmentally benign in comparison to other binary mixtures
used in industry. The cycle takes advantage of the varying boiling temperatures of the
ammonia/water mixtures to get a better there.
mal match with a sensible heat source. It also takes advantage of the low boiling
temperature of ammonia vapour to provide refrigeration. This cycle is designed as a
bottoming cycle for utilizing waste heat from a conventional power cycle or as an
independent cycle using low temperature sources such as geothermal and solar energy.
This cycle produces maximum efficiency compared to other forms of the cycles.
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CHAPTER 2
LITERATURE REVIEW
D. Yogi Goswami (2001) Novel Combined Power and Cooling ThermodynamicCycle for Low Temperature Heat Sources. This cycle can be used as a bottoming
cycle using waste heat from a conventional power cycle or as an independent cycle
using low temperature sources such as geothermal and solar energy
Kyoung Hoon Kim, Giman Kim, and Chul Ho Han (2012) PerformanceAssessment of Ammonia-Water Based Power and Refrigeration Cogeneration
Cycle. This study employs design for various combinations of power and
refrigeration and this cycle was optimized for efficiency with power.
M. M. Rashid, O.A. Beg and A. Aghagoli (2012) Utilization of waste heat incombined power and ejector refrigeration for a solar energy source intended
output. This study employs the combined power and refrigeration cycle which
combines the Rankine cycle and the ejector refrigeration cycle for a solar energy
heat source
Na Zhanga, Noam Liorb (2007) Methodology for thermal design of novelcombined refrigeration/power binary fluid systems; International Journal of
Refrigeration. This study employs Refrigeration cogeneration systems which
generate power alongside with cooling improve energy utilization.
Shaoguang Lu and D. Yogi Goswami (2002) Theoretical analysis of ammonia-based combined power/refrigeration cycle at low refrigeration temperatures. This
study employ a new combined power/refrigeration cycle uses ammonia/ water
mixture as a working fluid to produce both power and refrigeration in the same
cycle. The cycle may be designed for various combinations of power and
refrigeration.
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CHAPTER 3
SYSTEM DESCRIPTION
Ammonia water mixture (50% ammonia & 50% water) is sent into the vaporiser
where the feed is heated by the waste heat source and it is partially vaporised and then it is
sent to the flash separator where the vapour and liquid streams get separated. The ammonia
vapour at 100c and 1 bar is sent to the super heater where the vapour is heated to 50 0c and
10 bar is sent to the turbine where the gas expands to low temperature and then the power
is produced by the turbine. The output of the turbine is sent to the absorption tower and the
liquid stream from the flash separator is cooled in the recovery heat exchanger and sent to
the absorber .They get mixed and the mixture is available at low temperature. This stream
is sent to the air cooler for air conditioning system where the sensible heat is utilised for air
cooling. After utilisation of sensible heat, it is sent to the heat exchanger where the stream
is heated to some extent and then sent to the vaporiser and thus the cycle continues.
The method used for the shell and tube heat exchanger design here is the KERNs
method. Since more iterations are required and also for optimisation of the design, we
developed the Shell & Tube application software using the VISUAL BASIC Software.
This tool is very effective for the preliminary design of the shell and tube heat exchanger.
Initially the charts are converted into the respective equations and these equations are
written as a code in this tool and then all the formulas required to calculate the heat load,
LMTD, Number of passes and Number of tubes required, heat transfer coefficient, pressure
drop, heat transfer area and Overall heat transfer coefficient, etc., are also written in the
code
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FIGURE 3.1 FLOW SHEET FOR AMMONIA WATER SYSTEM
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CHAPTER 4
MATERIAL BALANCES
4.1 FLASH SEPERATOR
Assumptions:
Inlet mass flow rate = 1kg/s
Inlet ammonia composition = 0.50
Inlet water composition = 0.50
Vapour Pressure Data:
At 100C,
Vapour Pressure of Ammonia, = 4571 mmHgVapour Pressure of Water, = 11.5 mmHgEquations:
= = 1 = 1m*=ml*+ mv*From equation 1 & 2,
Pt= *+*From 3 & 5,
=
=
.
= 0.164
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From Equation 3,
=1-=.836
= =.1644571760
=.989=
=.. =.011Substituting,,,in equation 4,we get,ml= .5927 kg/s
mv= .4073 kg/s
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CHAPTER 5
ENERGY BALANCES
5.1 FLASH SEPARATER
Figure 5.1 FLASH SEPERATOR
Energy in = mLCPL TF +mV CPV TF
=[0.5927(4.58*0.164+4.22*0.836)*283+0.4073(2.1*0.989+1.86*0.023]
= 717.74+241.754
= 959.494 kW
Liquid
QL = mLCPLTh1
= [0.5627*(4.58*0.164+4.22*0.836)*283]
= 717.74 kW
Vapour
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QV = mVCPVTfv
= [0.4073*(2.1*0.989+1.86*0.011)*283]
= 241.754 kW
5.2 SUPER HEATER
Figure 5.2 SUPER HEATER
Inlet Energy = mvCpvTfv
= [0.4073*(2.1*0.989+1.86*0.011)*283]
= 241.754 kW
Energy Added = mvCpvT + mvRTfiln(p1/p2)
= mvCpv(Tti-Tfv) +mvRTtiln(p1/p2)
= [(0.4073*1.96*(50-10)) + (0.4073*8314/17.011*323*ln (1/10))]
= 31.93+148.15
= 180 kW
Outlet Energy = Inlet Energy +Energy Added
= 241.754+180
= 421.83 Kw
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5.3 TURBINE
Figure 5.3 TURBINE
Assuming the process is Adiabatic
Inlet Energy = Outlet Energy from the Super heater
Power produced =
[1
]
= .40738.314/17.0113231.31 [ 1 1101.311.3
]
W = 88.4 kW
Outlet Energy = Inlet Energy - Power produced
Inlet Energy = 421.83 kW
Power produced = 88.4kW
Outlet Energy = 421.83 -88.4
= 333.43 KW
Outlet Energy = mvCpTto
333.43 = 0.4073*4.47*Tto
Tto =183K
` Tto = - 900 C
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5.4 ABSORBER
Figure 5.4 ABSORBER
Inlet Energy = Energy from the Turbine + Energy from the Heat Exchanger
= mvCpTto +mLCpTh2
= 333.43 + 686.13
= 1019.56
Outlet Energy = Inlet Energy
Outlet temperature = Outlet energy
= mCpTa
= 1*4.4*Ta
Ta =232 K
Ta = -410C
Hence Outlet Energy = 1019.56 kW
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5.5 REFRIGERATION
Figure 5.5 REFRIGERATION
Inlet Energy from the absorber +Energy Added = Outlet of Absorber
1019.56 +Energy Added = 1113.2
Energy Added = 93.64 kW
Energy Added = mCpT
Assuming the air inlet temperature =400C
Assuming the air outlet temperature =200C
Mass flow rate of air = Energy Added/ (Cpair*Tair)
93.64 = mair*1*(40-20)
mair = 4.682kg/s
Mass Flow Rate = 4.682kg/s
5.6 HEAT EXCHANGER
Figure 5.6 HEAT EXCHANGER
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Inlet energy from the Flash Drum
At 100C
Q = mLCPTh1
= 0.5927*(4.58*0.164+4.22*0.836)*283
= 717.74 kW
Inlet energy to the HE from the Absorber
At -200C
Q = mCPTc1
= 1*4.4*253
= 1113.2 kW
Outlet Energy from the absorber to the Vaporiser
At -130C
Q = mLCPTc2
= 1*4.4*260
= 1144 kW
To find Th2:
Th2 = (Inlet EnergyEnergy to the Vaporizer)/mLCP
=(..)()
..
= 264 K
= -90C
Therefore, the outlet energy from HE to Absorber is = mLCPTh2
=.5927*4.385*264 =686.13 kW
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5.7 VAPOURISER
Figure 5.7 VAPOURISER
Energy added = Energy required to raise the Temperature + Latent Heat of vaporisation
=m*Cp*(Tf-Tc2) + mv*( + )=1*4.4*(283-260) + .4073*(.989*1200 + .011 * 2406)
=595.36 Kw
Energy added = 595.36 kW
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CHAPTER 6
DESIGN OF SHELL AND TUBE HEAT EXCHANGER
Mass flow rate of hot stream,mh = 0.5927 kg/s
Mass flow rate of hot stream,mc = 1 kg/s
Inlet temperature of hot stream,Th1 = 10oC
Outlet temperature of hot stream,Th2 = -9oC
Inlet temperature of cold stream,Tc1 = -20oC
Outlet temperature of hot stream,Tc2 = -13oC
Hot stream average temperature,ThAvg = 0.5oC
Cold stream average temperature,TcAvg = -16.5o
C
Property Table
S.No Property Unit Hot stream Cold stream
1. Cp J/kgoC 4280 4400
2. Kg/m 940.48 840
3. Pa.s (10- ) 1.49 1.65
4. K W/m.oC .565 .5587
Assumptions
Overall heat transfer unit,U0 = 600 W/m2.K.
Length of the tubes,L = 4 m.
Outer diameter of the tube,Do = 20 mm.
Inner diameter of the tube,Di = 16 mm.
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Baffle cut = 25%
Tube pitch,Pt = 1.25Do
Pt = 1.25*20
Pt = 25 mm
Thermal conductivity of cupro-nickel alloys = 50 W/m.K.
Number of Shell-side passes = 1
Number of Tube-side passes = 4
Logarithmic Mean Temperature Difference,
LMTD =()()
LMTD =(())(())
(())(())
LMTD = 16.27 oC
R =
R = 10(9)13(20)R = 0.3684
S =
S =
S = 0.633
Using temperature correction factor chart,
Ft = .97
Correct LMTD = Ft*LMTD
= .97*16.2
() = 15.714 oCHeat load Q = ()
= 1*4400(-13-(-20))
= 30.8 kW
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Assuming Overall heat transfer unit,U0= 600 W/m2.K
Heat transfer area,
Ah = ()Ah =
.
Ah = 3.25 m2
Assuming total heat transfer area =3 m2
Area of 1 tube =
DoL
= 3.14*0.02*4
= 0.251 m2
Total number of tubes required,
Nt =
Nt =
.Nt = 11.9 tubes
For Triangular Pitch,
Bundle Diameter,
Db = Do .
.
Db = 0.02* ..
.
Db = 0.116 m
Using a split-ring floating head,
From Shell bundle clearance chart,
Bundle diameter clearance,
BDC = 0.0477 m
Shell diameter,
Ds = Db + BDC
Ds = 0.116 + .0477
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Ds = 0.163 m
Tube side Coefficient
Tube cross sectional area,
A = DiA =
*0.016
A = 2.01*10-4m2
Tube per pass,
Tp =
.
Tp = 11.9/4
Tp = 3 tubes
Total flow area of tubes,
At = A*Tp
At = 2.01*10-4*3
At = 6*10-4m2
Tube-side velocity,
Vt = ()
() ()
Vt =
Vt = 1.984 m/s
Reynolds Number for tubes:
= = ... = 16178
Prandtl Number for tubes:
=
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= ..
= 12.98
= .= 250Using heat transfer factor chart, we get,
= 3.1 10 =(). = (). = .5587. 3.1 10 16178 (12.98). = 4081 W/m2.K
Shell-side Coefficient:
Baffle Spacing,
Bs = =
.
Bs = 0.0408 m
Shell-side flow area,
As =
As =
() 0.1630.0408
As = 1.33*10-3m2
Shell-side equivalent diameter,
De = 1.1 (2 0.9172)De =
.. (0.025 0.9170.02)
De = 0.0142 m
Shell-side velocity,
Vs = ()
flow() ()Vs = ..10.
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Vs = 0.473 m/s
Shell-side Reynolds Number:
= = ..473.. = 4242.7
Shell-side Prandtl Number:
=
= .. = 11.27
Using Shell-side heat transfer factor chart,
= 8.0*10-3 =(). = (). = .. 8 1 0 4242.7 (11.27). = 3028.3 W/m2.K
Overall heat transfer coefficient, Uo
1 =
1 +
+
2
1 =
13028.3 +
2016 4081+
0.0220162 5 0 1
=0.00068Uo = 1468 W/m2.K
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Tube side pressure drop
= 8 +2.52
Using Tube-side friction factor chart, we get,
=3.1*10-3 = 4 8 3 . 1 1 0 40.016 + 2.5
8401.9842
= 4 8 3 . 1 1 0 40.016 + 2.58401.984
2
= 57.54
= 8.35 Shell-side pressure drop
= 8
2 Using Shell-side friction factor chart, we get,
= 5.7*10-2 = 8 2
=8 5 . 7 1 02 40.0408 0.1630.0142 940.480.4732
2
= 54.05 kPa = 7.84 kPa
6.1 VISUAL BASIC CODING
Public Class shell_tube
to find corrected lmtd
Public Function Ft(ByVal th_1 As Integer, ByVal th_2 As Integer, ByVal tc_1 As Integer, ByVal tc_2 As
Integer, ByVal n As Integer) As Single
Dim p, r, rp, x, a, b, c, d, e, f, g, h, num, den As Single
p = (tc_2 - tc_1) / (th_1 - tc_1)
r = (th_1 - th_2) / (tc_2 - tc_1)
rp = (r * p - 1) / (p - 1)
rp = rp ^ (1 / n)x = (1 - rp) / (r - rp)
a = Math.Sqrt(r ^ 2 + 1)
b = a / (r - 1)
c = Math.Log((1 - x) / (1 - r * x))
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num = b * c
d = 2 / x - 1 - r + a
e = 2 / x - 1 - r - a
den = Math.Log(d / e)
Ft = num / den
f = (th_1 - tc_2) - (th_2 - tc_1)g = Math.Log((th_1 - tc_2) / (th_2 - tc_1))
h = f / gFt = Ft * h
End Function
Function fun_shell_dia(ByVal bun_dia As Single) As Single
Dim a, b, c, d As Single
b = bun_dia * 0.001If Head_type.SelectedIndex = 0 Then
a = 10 * b + 8
ElseIf Head_type.SelectedIndex = 1 Then
a = 38
ElseIf Head_type.SelectedIndex = 2 Then
a = 27 * b + 44.4ElseIf Head_type.SelectedIndex = 3 Then
a = 5 / 0.55 * b + 47.25 / 0.55
End If
Return ((a + bun_dia) * 0.001)
End Function
Public Function baffle15(ByVal b15 As Single) As Single
Dim a, b As Single
a = Math.Log(b15)
If b15 300 And b15 < 1000 Then
b = -0.3368 * a + 0.02376
Elseb = 0.001242 * a ^ 3 - 0.03154 * a ^ 2 + 0.08592 * a - 1.777
End If
b = Math.Exp(b)
Return b
End Function
Public Function baffle25(ByVal b15 As Single) As Single
Dim a, b As Single
a = Math.Log(b15)
If b15 300 And b15 < 1000 Then
b = -0.2962 * a - 0.6128
Elseb = 0.002014 * a ^ 2 - 0.1825 * a - 1.495
End If
b = Math.Exp(b)Return b
End Function
Public Function baffle35(ByVal b15 As Single) As Single
Dim a, b As Single
a = Math.Log(b15)If b15 300 And b15 < 1000 Then
b = 0.1113 * a ^ 2 - 1.709 * a + 3.721
Elseb = -0.003228 * a ^ 2 - 0.111 * a - 1.853
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End If
b = Math.Exp(b)
Return b
End Function
Public Function baffle45(ByVal b15 As Single) As Single
Dim a, b As Singlea = Math.Log(b15)
If b15 300 And b15 < 1000 Then
b = -0.2795 * a - 1.065
Else
b = -0.004517 * a ^ 2 - 0.08661 * a - 2.182End If
b = Math.Exp(b)
Return b
End Function
Public Function baffle_ht_15(ByVal b15 As Single) As Single
Dim a, b As Singlea = Math.Log(b15)
If b15
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Return b
End Function
Public Function tube_heatlam(ByVal nrelam As Single, ByVal ld As Single) As Single
Dim a, b As Single
a = Math.Log(nrelam)
If ld = 24 Thenb = -0.6419 * a - 1.335 + 0.82
ElseIf ld > 24 And ld 48 And ld 120 And ld 240 And ld
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b = 2.675
End If
ElseIf pitch_combo.SelectedIndex = 1 Then
If tube_passes.Text = 1 Then
a = 0.215
b = 2.207ElseIf tube_passes.Text = 2 Then
a = 0.156b = 2.291
ElseIf tube_passes.Text = 4 Then
a = 0.158
b = 2.263
ElseIf tube_passes.Text = 6 Thena = 0.0402
b = 2.617
ElseIf tube_passes.Text = 8 Then
a = 0.0331
b = 2.643
End IfEnd If
c = d * (n / a) ^ (1 / b)
Return (c)
End Function
Public Function Nre(ByVal d As Single, ByVal v As Single, ByVal rho As Single, ByVal mu As Single) As
Single
Return (d * v * rho / mu)
End Function
Public Function Npr(ByVal cp As Single, ByVal mu As Single, ByVal k As Single) As Single
Return (cp * mu / k)
End Function
Public Function heat_coeff(ByVal k As Single, ByVal d As Single, ByVal nre As Single, ByVal npr As
Single, ByVal jh As Single)Return (jh * k / d * nre * (npr) ^ 0.33)
End Function
Public Function calc_Uo(ByVal ht1 As Single, ByVal hs1 As Single, ByVal d As Single, ByVal di As
Single, ByVal k As Single,
ByVal foul_t As Single, ByVal foul_s As Single) As Single
Dim a, b, c As Single
a = 1 / hs1 + foul_s + foul_t * d / di + d / di / ht1
b = d / (2 * k) * Math.Log(d / di)
c = a + b
c = 1 / cReturn (c)
End Function
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) HandlesButton1.Click
'heat load
Dim delT, qh, Ah, Db, tube_per_pass As SingleDim Area_1_tube, No_tube, shell_dia, tube_csa As Single
Dim tube_flow_area, tube_vel, tube_nre, tube_npr As Single
Dim tube_heat_factor, ht As Single
Dim shell_csa, shell_vel, de, shell_nre, shell_npr As Single
Dim shell_heat_factor, hs, act_Uo As Singleqh = heatload(hot_flow.Text, hot_cp.Text, th1.Text, th2.Text)
delT = Ft(th1.Text, th2.Text, tc1.Text, tc2.Text, 1)
Ah = qh / (Uo.Text * delT)
r_ht_area.Text = Ah
'res_A.Text = AhArea_1_tube = Math.PI * d_o.Text * Len_tube.Text
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No_tube = Ah / Area_1_tube
r_ntubes.Text = No_tube
Db = bundle_diam(d_o.Text, No_tube)
shell_dia = fun_shell_dia(Db * 1000)
tube_csa = Math.PI / 4 * d_i.Text ^ 2
tube_per_pass = No_tube / tube_passes.Texttube_flow_area = tube_per_pass * tube_csa
tube_vel = cold_flow.Text / (tube_flow_area * cold_density.Text)tube_nre = Nre(d_i.Text, tube_vel, cold_density.Text, cold_viscosity.Text)
tube_npr = Npr(cold_cp.Text, cold_viscosity.Text, cold_k.Text)
If tube_nre < 2000 Then
tube_heat_factor = tube_heatlam(tube_nre, Len_tube.Text / d_i.Text)
Elsetube_heat_factor = tube_heat_turb(tube_nre)End If
ht = heat_coeff(cold_k.Text, d_i.Text, tube_nre, tube_npr, tube_heat_factor)
tube_pitch.Text = 1.25 * d_o.Text
baffle_space = shell_dia / (baffle_spacing.Text - 1)
shell_csa = (tube_pitch.Text - d_o.Text) / tube_pitch.Text * shell_dia * baffle_space
shell_vel = hot_flow.Text / (shell_csa * hot_density.Text)If pitch_combo.SelectedIndex = 0 Then
de = 1.1 / d_o.Text * (tube_pitch.Text ^ 2 - 0.917 * d_o.Text ^ 2)
ElseIf pitch_combo.SelectedIndex = 1 Then
de = 1.27 / d_o.Text * (tube_pitch.Text ^ 2 - 0.785 * d_o.Text ^ 2)
End If
shell_nre = Nre(de, shell_vel, hot_density.Text, hot_viscosity.Text)
shell_npr = Npr(hot_cp.Text, hot_viscosity.Text, hot_k.Text)
If baff_cut.SelectedIndex = 0 Then
shell_heat_factor = baffle_ht_15(shell_nre)
ElseIf baff_cut.SelectedIndex = 1 Then
shell_heat_factor = baffle_ht_25(shell_nre)
ElseIf baff_cut.SelectedIndex = 2 Then
shell_heat_factor = baffle_ht_35(shell_nre)ElseIf baff_cut.SelectedIndex = 3 Then
shell_heat_factor = baffle_ht_45(shell_nre)
End If
hs = heat_coeff(hot_k.Text, de, shell_nre, shell_npr, shell_heat_factor)
act_Uo = calc_Uo(ht, hs, d_o.Text, d_i.Text, mat_k.Text, cold_fouling.Text, hot_fouling.Text)
jft = tube_friction(tube_nre)
delpt = tube_passes.Text * (8 * jft * Len_tube.Text / d_i.Text + 2.5) * cold_density.Text * tube_vel ^ 2 / 2
If baff_cut.SelectedIndex = 0 Then
jfs = baffle15(shell_nre)
ElseIf baff_cut.SelectedIndex = 1 Thenjfs = baffle25(shell_nre)
ElseIf baff_cut.SelectedIndex = 2 Then
jfs = baffle35(shell_nre)ElseIf baff_cut.SelectedIndex = 3 Then
jfs = baffle45(shell_nre)
End Ifdelps = 8 * jfs * (shell_dia / de) * (Len_tube.Text / baffle_space) * hot_density.Text / 2 * shell_vel ^ 2
Uo_calc.Text = act_Uo
tube_pres.Text = delpt / 6895
shell_pres.Text = delps / 6895
rt_ht.Text = htrt_npr.Text = tube_npr
rt_nre.Text = tube_nre
rt_vel.Text = tube_vel
rs_hs.Text = hs
rs_npr.Text = shell_nprrs_nre.Text = shell_nre
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rs_vel.Text = shell_velEnd SubEnd Class
Figure 6.1 SHELL AND TUBE APPLIACTION SOFTWARE
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6.2 PICTORIAL REPRESENTATION
Figure 6.2 SHELL AND TUBE HEAT EXCHANGER
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CHAPTER 7
CONCLUSION
Thus we understand the combined power and refrigeration cycle produces the
maximum efficiency, recovery of maximum energy from the waste heat source to produce
both the power and the refrigeration. The power produced is about 88.4 KW.A computer
program based on the VISUAL BASIC code for the optimisation of the design of shell and
tube heat exchanger has been developed to design the shell and heat exchanger. From this
we understand this application is very effective for calculating the heat load, LMTD,
Number of passes and Number of tubes required, heat transfer coefficient, pressure drop,
heat transfer area and Overall heat transfer coefficient, etc.
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REFERENCES
1. Lu.S., Goswami, (1994) Performance Assessment of Ammonia-Water Based Power
and Refrigeration Cogeneration Cycle.
2. Gunnar Tamm, D. Yogi Go swami (2002) Novel Combined Power and Cooling
Thermodynamic Cycle for Low Temperature Heat Sources.
3. M. M. Rashid, O. A. Beg (2001) and A. Aghagoli Utilization of waste heat in combined
power and ejector refrigeration for a solar energy source.
4. Na Zhanga, Noam Loir (2006) Methodology for thermal design of novel combinedrefrigeration/power binary fluid systems, International Journal of Refrigeration.
5. Ram Darash Patel, Priti Shukla (2000) International journal of research in aeronautical
and mechanical engineering, Thermodynamics analysis and optimization for a combined
power and refrigeration cycle.
6. Lu.S., Goswami, (2002) Theoretical based combined power /refrigeration cycle at low
refrigeration temperature.
7. Xu Feng, Goswami D. Yogi, Bhagwat Sunil S., (2000), A combined power/cooling
cycle, Energy 25 (2000) 233246.
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STUDIES ON CIRCULATING FLUIDISED BED
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CHAPTER 1
INTRODUCTION
Homogeneity in multi-phase reaction systems are generally carried out to maintain
the uniform suspension of solids and also to maintain the stability in reaction kinetics, on
other hand homogeneity is maintained to reduce the amount of catalyst consumption. Need
of homogeneity is mainly to control the value of conversion and also to reduce the
operating fluctuations of the reactor. Due to formation of dead zones a pasty catalyst form
as lumps on the wall side of the reactor. When those lumps enter the fluidization area
where the reaction takes place a sudden rise in the temperature of the reactant takes place.
To prevent reactor from running out of condition, formation of lumps should be prevented.
Main drawback in forced circulation fluidized bed reactor is the formation of dead zones.
Due to this reason maintaining of the homogeneity is tedious in the fluidized bed reactor.In order to maintain the homogeneity, change in design aspects or placing agitator is
needed. Literatures were reviewed to find the solution for the above problem. The possible
solutions obtained are listed below:
Varying the different variables like
Catalyst pellet size Fluidization velocity Viscosity of the feed Feed inlet condition Placing an external mixing equipment like agitator While changing the above variables there may be some drawbacks. When the size
of the catalyst is changed from 1mm surface area reduces and increases the catalyst
consumption rate. Actual operating condition of the reactor is 15 to 16C.Astemperature is inversely proportional to viscosity thus it affects the operating
condition of the reactor and also it affects the grade off the polymer
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While varying the flow rate it is directly proportional to the fluidization velocity.When flow rate increases fluidization velocity increases entrainment of particles
take place and it increases the circulation rate but decreases the conversion.
If the flow rate is decreased then it will affect the fluidization velocity thus itinduces the formation of hot spots. In case of altering the feed conditions the
reaction rate and kinetic will affect. Reactant is first precooled using refrigerant
before it is sent in to the reactor. Maintaining the refrigerant rate is one of the ways
to maintain process temperature of the reactor. But there is some fluctuation in the
refrigerant rate since the reaction is exothermic. On considering the above
drawbacks and also by referring the various literatures, finally the best method of
overcome this issue is placing a spiral type agitator suspended at one end. The
hydrodynamic study was carried out for the starch system using biocatalyst and the
solid distribution was calculated for varying liquid flow rate and solid
concentrations.The correlation was developed between the Solid circulation
number, Reynolds Number and the Velocity number.
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CHAPTER 2
LITERATURE REVIEW
Akifumi Kato, Ohtake et al (1999) have studied Anchor Agitator for gaseousphase polymerisation vessel.This study employed an Anchor agitator for uniform
and effective stirring of the Fluidised bed zone of a polymerization vessel in a
gaseous phase polymerisation reaction.
Jr grace, c j lim, cmh brereton and j chaouki (2001) Circulating fluidized bedreactor design and operation. This study is helps to know about the Introduction to
circulating fluidised bed reactor
Jukka koskinen, Espoo; Henrik Andtsjo, et al (1997) have studied Methods forpolymerizing olefin in a fluid bed reactor. This study employed the homogeneity
of solids in the fluidized bed reactor and also how the polymerization reaction is
carried out.
Biao Wang, Tao Li, Qi-wen Sun, Wei-yong Ying, and Ding-ye Fang (2001) studieda Solid Concentration in Circulating Fluidized Bed Reactor for the MTO Process.
The effects of radial distance, axial distance, superficial gas velocity, initial bed
height on solid concentration in the bed and the effects of distributor shape and
porosity on solid concentration is discussed.
Joelle Aubin, Cathrine Xuereb et al (2005) have studied Design of multipleimpeller stirred tanks for the mixing of highly viscous fluids using CFD .This
study helped to know the effect of multiple Intermig impeller configuration on
hydrodynamics and mixing performance in stirred tank of computational fluid
dynamics
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CHAPTER 3
MATERIALS AND METHODS
3.1 MATERIALS USED
The set up for the circulating fluidised bed was fabricated, with the
specifications of about Riser diameter 28 cm and the Riser height 40 cm.The agitator is
spiral type. This spiral agitator has one end suspended and other end as free end. The spiral
agitator was chosen because the hollow portion of the agitator does not affect the
fluidization taking place inside the reactor. The disturbance produced by this type is
comparatively less when compared to other type of agitators in mixing viscose liquids.
This agitator was connected to the motor by the shaft connected to the spiral structure. The
dimension of the spiral agitator was made according to the ratio of reactor dimension. The
specification of the agitator with Diameter 23 cm, Pitch 8 cm, Width 1.25 cm, Thickness
0.4 cm and no. of. Turns 3.5.
Figure 3.1 SPIRAL AGITATOR
The viscose fluid used to carry out the hydrodynamic analysis in the lab scale model was
starch solution. Thus the properties of starch as follows
Molecular formula :(C12H22O11)n
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Density : 1.5gm/cm3
Thus the viscosity of starch solution was chosen to carry out the hydrodynamic analysis in
the lab scale model. And the handling of starch solution is also comparatively easy with
high availability and cost effective.
For the solid catalyst particle the bio catalyst was used to carry out the
polymerization reaction. The bio catalyst was chosen because the specific gravity of the
bio catalyst is low and helps in the better polymerization.
3.2 METHODS USED:
The response which should be noted was the solid composition in the product
stream. The uniformity of the solid composition in the product stream denoted that there is
no lumping of catalyst solid particles taking place. Thus the problem of solid lumping can
be avoided by this analysis.
The variables in the process are:
Flow rate Solid loading
Thus for the varying concentration and flow rate the solid composition is
measured. The concentration of feeding solution is 10% and 20% starch solution and the
flow rate as 300,350,400,450 and 500 ml/sec. For every value of Concentration and flow
rate the solid composition was measured.
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CHAPTER 4
Figure 4.1 EXPERIMENTAL SETUP
4.1 EXPERIMENTAL PROCEDURE:
The liquid is pumped in to the reactor and the circulation of the fluid is made by the
continued running of the pump. The required flow rate is fixed by adjusting the pump
regulator for one value of Q. The measured quantity of solid was taken and added to the
circulating liquid. The sample of 100ml of liquid along with solid in the circulation stream
was taken at the intervals of 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 minutes. The solids present in
the sample was separated, dried, and weighed. Thus the weights of the solid particles were
noted for the corresponding time intervals. The concentration in terms of Kg of solids
present/ m3 of sample collected was calculated. This procedure is repeated for with and
without agitator and for each and every concentration and flow rate. Thus the plot of
concentration versus time can be used to show the uniformity in solid composition.
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TABLE 5.3 SOLID LOADING=4 KG & 10% STARCH SOLUTION
FLOW RATE
ml/sec SOLID LOADING kg
CONC
gm/lit
300 4 27.5
350 4 37.6
400 4 42.3
450 4 58.6
500 4 66.9
TABLE 5.4 SOLID LOADING=4 KG & 20% STARCH SOLUTION
FLOW RATE
ml/sec
SOLID LOADING
kg
CONC
gm/lit
300 3 42.6
350 3 66.7
400 3 73.56
450 3 89.8
500 3 112.3
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Figure 5.1 CONCENTRATION (gm/lit) Vs. FLOW RATE (ml/sec)(without stirrer)
0
10
20
30
40
50
60
70
80
90
100
110
120
250 300 350 400 450 500 550
C
ONCENTRATION
(gm/lit)
FLOW RATE
(ml/sec)
WITHOUT STIRRER
20% SOLUTION & 4 kg
LOADING
20% SOLUTION & 3 kg
LOADING
10% SOLUTION & 4 kg
LOADING
10% SOLUTION & 3 kg
LOADING
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WITH STIRRER
TABLE 5.1 SOLID LOADING=3 KG & 10% STARCH SOLUTION
TABLE 5.2 SOLID LOADING=3 KG & 20% STARCH SOLUTION
TABLE 5.3 SOLID LOADING=4 KG & 10% STARCH SOLUTION
TABLE 5.4 SOLID LOADING=4 KG & 20% STARCH SOLUTION
S.NO FLOW RATE ml/sec CONC gm/lit DEL_P N/m2
1 300 21.6 1238.6
2 350 27.6 1518.1
3 400 39.6 1658.4
4 450 48 1869.7
5 500 55.2 2017.5
S.NO FLOW RATE ml/sec CONC gm/lit DEL_P
6 300 43.2 2366.8
7 350 46.8 2588.1
8 400 57.6 2861.5
9 450 63.6 3335.8
10 500 82.8 3611.3
S.NO FLOW RATE ml/sec CONC gm/lit DEL_P
11 300 28.8 1847.34
12 350 38.4 2019.7
13 400 46.4 2365.7
14 450 59.2 2526.7
15 500 67.2 2783.3
S.NO FLOW RATE ml/sec CONC gm/lit DEL_P
16 300 48 3752.556
17 350 65.6 4022.127
18 400 76.8 4578.705
19 450 97.6 5170.786
20 500 103.2 5730.871
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Figure 5.2 CONCENTRATION (gm/lit) Vs. FLOW RATE (ml/sec)
Figure 5.3 PRESSURE DROP (N/m2) VS FLOW RATE (ml/sec)
0
10
20
30
40
50
60
70
80
90100
110
120
250 300 350 400 450 500 550
CONCENTRATION(gm
/lit)
FLOW RATE (ml/sec)
WITH STIRRER20% solution & 4 kg
loading
20% solution & 3 kgloading10% solution & 4 kg
loading10% solution & 3 kg
loading
0
1000
2000
3000
4000
5000
6000
7000
250 350 450 550PRESSUREDROP
(N/m2)
FLOW RATE
(ml/sec)
WITH STIRRER
20% solution & 4 kg
loading20% solution & 3 kgloading10% solution & 4 kg
loading
10% solution & 3 kgloading
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CORRELATION
= 1.337*().*().*.
+ . 8735 .
Where,
Solid Circulation Number,= ( ) ()
()
Velocity Number,=
Reynolds Number,
=
Ratio = Length to Diameter ratio of the Riser.
Correlation was developed between the Solid Circulation Number, Reynolds
Number, Velocity Number and (L/D) ratio of the riser. From the Correlation, we come into
conclusion that the Solid Circulation rate increases with the increase in the viscosity of the
fluid and also with the increase in the velocity. It increases with the decrease in the
terminal settling velocity of the particle which intern shows that when the particle size is
reduced, the Solid Circulation rate increases. And also the solid circulation rate increases
with the increase in the (L/D) ratio..
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CHAPTER 8
CONCLUSION
The hydrodynamics studies were conducted for the circulating Fluidized bed using
stirrer for starch solution and bio catalyst. The effect of flow rate, fluid properties such as
viscosity, density and the solid loading on the solid circulation rate and the pressure drop
were studied. Hence the usage of agitator thus removes the dead zones, and prevents the
lump formation. The correlation was developed between the Solid number, Reynolds
Number and the Velocity number.
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REFERENCES
1. Akifumi Kato, Ohtake; et al (1999) have studied Anchor Agitator for gaseous phase
polymerisation vessel.
2.Biao Wang, Tao Li, Qi-wen Sun, Wei-yong Ying, and Ding-ye Fang (2001) studied aSolid Concentration in Circulating Fluidized Bed Reactor for the MTO Process.
3. Grace Jr, C J Lim, Cmh Brereton and J Chaouki, Circulating fluidized bed reactor
design and operation.
4. Joelle Aubin, Cathrine Xuereb et al (2005) have studied Design of multiple impeller
stirred tanks for the mixing of highly viscous fluids using CFD.
5. Jukka koskinen, Espoo; Henrik Andtsjo, et al (1997) have studied Methods for
polymerizing olefin in a fluid bed reactor.
6. P.Natarajan, R.Velraj, R.V.Seeniraj (2001) have studied Hold up and solid circulations
rate in liquid solids circulating fluidized bed.
7.Siva lingam Amanda and Dr.T.Kannadasan Effect of Fluid Flow Rates on
Hydrodynamic Characteristics of Co-Current Three Phase Fluidized Beds with Spherical
Glass Bead Particles.
8. Thomas Ward, Asher Metchik et al (2008) have studied Viscous fluid mixing in a tiltedtank by period shear.