Theoretical Analysis of Coil finned tube type
Heat Exchanger for helium liquefaction Plant
SJ
1
Patel ,
SM
2
Mehta ,
KP
3
Desai and
HB
4
Naik
1, 2 L. D. College of Engineering, Ahmedabad, Gujarat, India
3,4 S.V.National Institute of Technology, Surat, Gujarat, India
[email protected]
ABSTRACT
The aim of present study is to design and optimize different geometrical and operating parameters for coiled finned tube exchangers.
To improve the effectiveness of heat exchanger the theoretical analysis has been carried out by theoretical modelling. The efforts have
been made to study the effect of different geometrical parameters like coil diameter, tube diameter by in depth study of DIN number,
fin height and fin spacing etc. and operating parameters like pressure drop. The design and optimization of geometrical and operating
parameters are done to achieve the desired temperature drop of cold fluid. The variation in properties of helium for specified
temperature range are studied and taken into consideration.
Parameters affecting sizing and
performance of Heat Exchanger are as
follow:
1. Physical parameters
• Tube diameter, shell diameter, Fin
height, Fin density, Diametrical
clearance.
2. Operating parameters
• Working pressures, Mass flow rates,
Four End temperature
6000
9000
5000
Pressure drop shell side(Kg/m2)
8000
4000
Phin = 14 bar
Pcin = 1 bar
Thin = 300K
Tcin = 85 K
7000
3000
6000
2000
5000
1000
pressure drop in shell side(Kg/m2)
cooling capacity
effectiness
Pressure drop shell side(Kg/m2)
Phin = 14 bar
Pcin = 1 bar
Thin = 300 K
Tcin = 85 K
0.9
0.8
500
520
540
560
580
600
620
Fin density( no. of fins per unit tube length
640
660
700
pressure drop in shell side(Kg/m2)
10000
600
700
680
Figure 6 Effect of fin density
100
4000
ovearall heat transfer coefficient
4
5
6
7
8
0
10
9
mass flow rate(Kg/s)
Pressure drop shell side(Kg/m2)
-3
x 10
overall heat transfer coefficient
Figure 2. Effect of mass flow rate
Effect of mass flow rate
1
6000
Phin = 14 bar
Pcin = 1 bar
Thin = 300 K
Tcin = 85 K
Dm = 145 mm
di = 8.2 mm
n = 670
c = 0.6 mm
80
2000
pressure drop in shell side
4000
3
Effectiveness
Pressure drop shell side(Kg/m2)
0.9
4000
Phin = 14 bar
Pcin = 1 bar
Thin = 300 K
Tcin = 85 K
0.8
2000
60
0.0125
0.013
0.0135
0.014
fin diameter
0.0145
0.015
0
0.0155
Figure. 7. Effect of fin diameter
CONCLUSION
0.7
3
4
5
6
7
8
0
10
9
Mass flow rate(Kg/s)
-3
x 10
Figure 3. Effect of mass flow rate
2. Effect of Geometrical parameters
Effect of mass flow rate
5000
4800
4600
−0.2
4400
cooling capacity
ℎ𝑜 = 0.021 ∗ 𝐶𝑐 ∗ 𝐺𝑓 ∗ 𝑅𝑒𝑓
------------[1]
−1.8
0.8
0.2
ℎ𝑖 = 0.033 ∗ 𝐶ℎ ∗ 𝑚ℎ ∗ 𝜇ℎ ∗ 𝑑𝑖
---[2]
Effectiveness of Heat exchanger
Effect of mass flow rate
pressure drop in shell side(Kg/m2)
DESIGN CONSIDERATION
800
1. Effect of operating parameters
Cooling capacity(W)
• Helium is widely used in space
research, superconducting magnets and
medical field. To conserve it, every
research Institute using helium in large
scale should have a helium liquefier.
• Consumption of helium increases by 4
to 5% every year.
• Recuperative Heat exchanger Plays
Vital role
and its Effectiveness
determines yield in liquefaction
system.
• Effectiveness reduces from 97 to 95%
leads to 12% reduction in yield
• Coiled finned tube type heat exchanger
widely used in medium capacity
helium liquefier.
RESULTS AND DISCUSSION
Effectiveness
INTRODUCTION
1
Dm1 = 125 mm
Dm2 = 145mm
Dm3 = 155 mm
4200
4000
Phin = 14 bar
Pcin = 1 bar
Thin = 300 K
Tcin = 85 K
3800
3600
3400
3200
3000
3
3.2
3.4
3.6
3.8
4
Mass Flow rate(Kg/s)
4.2
4.4
4.6
4.8
5
-3
x 10
Figure .4 Effect of mean coil diameter
57.6
• Tube side pressure nearly remains
constant while shell side pressure drop
has been affected by fin geometry.
• Fin density, fin height, fin diameter
can be optimised by considering
effectiveness and pressure drop of
heat exchanger.
• Present study indicates that for given
range of operating parameters
Geometrical Parameters can be
optimised
ACKNOWLEDGEMENT
The authors are thankful to Department of Science and
Technology, for supporting research work, Vide letter no.
SB/FTP/ETA-0014/2014.
400
ovearall heat transfer coefficient
Pressure drop shell side(Kg/m 2)
Figure. Schematic diagram of Heat Exchanger
Phin = 14 bar
Pcin = 1 bar
Thin = 300 K
Tcin = 85 K
57.2
360
57
340
56.8
320
56.6
REFERENCES
380
0.075
0.08
0.085
DIN = di/Dm
Figure. 5 Effect of DIN No.
0.09
300
0.095
pressure drop in shell side
overall heat transfer coefficient
57.4
[1] Randall F. Barron, cryogenic heat transfer, Taylor and Francis,
1999.
[2] Gupta P.K.,kush P.K.,Tiwari A., 2007b. Design and optimisation of
coil finned tube heat exchangers for cryogenics application.
Cryogenics 47, 322-332.
[3] Atrey MD. Thermodynamic analysis of Collins helium liquefaction
cycle. Cryogenics 1998; 38: 1199–206.
[4] Gupta Prabhat Kumar, Kush PK, Tiwari Experimental research on
heat transfer coefficients for cryogenic cross-counter flow coiled
finned tube heat exchangers. International Journal of Refrigeration
2009; 32(5):960–72.
[5] Gupta Prabhat Kumar, Kush PK, Tiwari A. Experimental studies
on pressure drop characteristics of cryogenic Cross-counter flow
coiled finned tube heat exchangers,Cryogenics 50(2010)257-265.