MET 440 Heat Transfer Design Project
Shell-and-Tube Heat Exchanger Design
Emory Bare
Keith Moll
MET-440 Heat Transfer
Old Dominion University
12/10/2015
Table of Contents
1) Summary
2) List of Figures and Tables
3) Specifications and Design Philosophy
4) Sources Used
5) Material and Specifications
6) Preliminary Drawings and Sketches
7) Final Drawings
8) Results
9) Iterations
10) Final Design Specifications
11) Tables
12) Discussion
13) Conclusion
14) References
15) HX Data Sheet
Summary
A shell and tube heat exchanger is to be designed cool liquid ammonia from 122F to 86F
using liquid water at 50F. The water can only reach 80F. The design is to be engineered such that
the length of the tube is 24 feet or less, and standard materials are to be chosen. Standard
engineering practices are to be used, with reasonable effectiveness that is to be verified. A
standard data sheet is to be provided at the end of the design.
List of Figures and tables
Figure 1: Shell, front-end and rear-end head types
Figure 2: Two-pass tube, single pass shell heat exchanger
Figure 3: Square 90 degree tube layout
Figure 4: Single Segment Baffle Layout
Specifications and Design Philosophy
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A shell-and-tube heat exchanger was designed to cool 320,000 lb/hr of liquid ammonia
from 122F to 86F with liquid water at 50F. The following specifications were to be met.
The water can only reach up to 80F.
Commercial tubing with a BWG gauge of 16 must be used
A maximum tube length of 24 feet is required due to space limitations.
You cannot use fins.
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
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The velocity inside the tubes cannot exceed 10 ft/s to prevent erosion.
Use a baffle cut of 25%.
The pressure drop on both sides of the heat exchangers cannot exceed 10 psi.
Design has to have a reasonable effectiveness.
Sources Used
Our Textbook Engineering Heat Transfer: Third Edition, William S. Janna
Thermal Conductivity of liquid Ammonia pdf provided.
The viscosity of Ammonia pdf provided
Thermodynamic Properties of Ammonia
Lectures for MET 440 Heat Transfer, Ayala Fall 2015 Old Dominion University
Materials and Specifications
Shell Material: Aluminum
K=164 W/m*k
Shell Fluid: Ammonia
Thermal Conductivity=0.4930 W/m*k, Density=580 kg/m3, To=30C, Ti=50C
Viscosity=3.40X10^-07 m2/s, Heat Capacity=4999 J/kg*k
Tube Material: Aluminum
Tube Fluid: Water
Thermal Conductivity=0.597 W/m*k, Density=1000 kg/m3, To=14C, Ti=10C
Viscosity=1.01X10^-06 m2/s, Heat Capacity=4181 J/kg*k
Baffle Material: Aluminum
Preliminary Drawings and Sketches
Our Initial Design was started with a selection of Stainless Steel 304 material. This was
changed during the design process. The following shows the preliminary design and sketches.
Final Drawings
Figure 1: Standard shell types, and front-end and rear-end head types. (TEMA Standards, (1988): Tubular
Exchanger Manufacturers Association, New York.
Shell and Tube Specifications:
 Front End Stationary Head Type: A, Channel and Removable Cover
 Shell Type, E, One Pass Shell.
 Rear End Head Type: M, Fixed Tubesheet
Figure 2: Two-pass tube, baffled single-pass shell, shell and tube heat exchanger designed for mechanical cleaning
of the inside of the tubes.
Figure 3: Square 90* Tube Arrangement
Figure 4: Single-Segment Baffle Layout
Results
Imputed values that can be changed
Calculated from other variables
Grayed values should always be the same
Need to be checked
Properties
Material
Density
Viscosity
Thermal Conductivity
Heat capacity
T1 = Inlet tube side fluid temperature
t2 = Outlet shell side fluid temperature
T2 = Outlet tube side fluid temperature
t1 = Inlet shell side fluid temperature
Mass flow rate m
q=m*cp*(t1-t2) THIS IS q TARGET
Computed q= Uo*Ao*Delta Tlm
Shell Side (HOT)
Ammonia
T bulk average
=40C
580 Kg/m^3
3.40E-07 m^2/s
4999 J/Kg*K
Tube side (COLD)
Water
T bulk average
=17.5C
1000 Kg/m^3
1.01E-06 m^2/s
4181 J/Kg*K
10 C
30 C
14 C
50
40.319
4031093.62
4020157.55
C
Kg/s
J/s
J/s
241.0364518 Kg/s
4031093.62 J/s
Selected Data
Selected U
Pipe INFO
Critical velocity
Np Number of passes
calc Nt =(m/Density*v)(4*Np/pi*Di^2)
ACTUAL SELECTED Nt
650 W/m^2*k
1 Inch
OD
0.0254 m
3 m/s
2
317.1276812
460
Calculations
t2-T1
T2-t1
20 K
36 K
ΔTlm cf=
F (correction factor)
ΔTlm*F
27.22076045
0.9
24.4986844 K
NEEDED Area outside Ao = q/u*ΔTlm
Calculated Length ( Ao/pi*Do*Nt )
ACTUAL LENGTH SELECTED
253.1434909 m^2
6.896446061 m
6.9 m
7.3152 m
ACTUAL Ao Total tube area = Pi*Do*L*Nt
253.2739431 m^2
Shell Size
Shell Od (one shell) TABLE 8.3
Nt number of tubes
Layout 90 deg Pitch P=
Np number of passes
Pipe material
Uo =
1/Uo=(ro/ri)*(1/hi+Rfi) continued below
+ ro*((LN(ro/ri))/k) + (Rfo+(1/ho))
ro/ri
ro =
ri = tube internal radius
hi = (Nu*K)/D(pipe dia)
ho= (Nu*K)/D(shell dia)
Rfi = tube fouling factor use .001 (hr*ft^2*F)/Btu
k = pipe material conductivity
Rfo = Fouling factor shell .001 (hr*ft^2*F)/Btu
Thickness
De =Equiv Dia (4(Pt^2-Pi*do^2)/4)/(Pi*do)
Crossflow area at center of shell = As
As = (Ds*C*B)/Pt
C = clearance
B = baffle Spacing recommended is SHELL DIA/5
Estimated Mass Velocity shell side Gs=M/As
SI
33 Inch
460
1.25 inch
2
Aluminum
647.9027138 W/m*K
0.001543442
1.149425287
0.0127
0.011049
6427.500459
9331.724278
0.00058
164
0.00058
0.065
0.025131694
0.02810317
0.00635
0.16764
1434.67803
m
m
W/m*K
W/m*K
m*k/w
w/m*k
m*k/w
in
M
m^2
M
M
Kg/m^2*s
External (in shell )
Nu= .36*(Re)^.55*(Pr)^(1/3)
k for ammonia
Re=(V*De)/viscocity
V=M/(density*A)
pr
475.70
0.4930 W/m*k
310574.15
0.12598 m/s
2
Internal ( in pipes )
Nu = .023*Re^(4/5)*Pr^n
NOTE n = 0.3 if Tw<Tb (cooling)
Pr
0.8382 M
0.551804445 m^2
0.03175 M
273.4648437
0.3
7.02
0.001651m
not sure if this is correct
Re =(V*D)/v ( single tube )
velocity V = Q/A/(Nt/Np)
Re =(4*m)/(Densiy*v*Pi*Di) ( single tube )
Re single tube * Np/Nt = acutal Re reynolds
k for water
q= Uo*Ao*Delta Tlm
59784.78
2.732493074
13750500.34
59784.7841
0.597
4020157.554
m/s
Not to exceede
3m/s
Turbulant
W/m*k
J/s
Iterations
Iteration Material
Np
4 Aluminum
3 Aluminum
2 Stainless Steel
1 Stainless Steel
2
2
2
2
Nt
Selected U
Calculated Uo Pipe OD (inch) Shell OD (inch) Tube Pitch (inch) Hi (W/m*k) Ho (W/m*k) Length (m) Velocity (m/s) Target q (J/s) Calculated q (J/s) Accuracy
460
650
647
1
33
1.25
6427.5
9331.7
6.9
2.73
4031093.62
4020157.55
99.73%
270
1500
292.69
1
21.25
1
5978.24
553.5
7
2.49
4031093.62
667653.17
16.56%
270
1750
11.4
0.75
21.25
1
175717.8
1406.58
7
2.79
4031093.62
26293.46
0.65%
270
1750
0.61
0.75
21.25
1
3435.5
555.23
7
1.13
4031093.62
1633
0.04%
Final Design Specifications
Shell and Tube Material: Aluminum
Tube Pitch: 90 degree square pitch, 1.25 inch spacing
Tube Diameter: 1 inch OD
Tube Length: 6.9 meters, 22.64 feet
Number of Tubes: 460
Number of Passes: 2 pass tubes, 1 pass shell
Shell Diameter: 33.0 inches
Type of Shell and Heads: Front End Stationary Head Type: A, Channel and Removable Cover. Shell Type, E, One Pass Shell.
Rear-End Head Type: M, Fixed Tubesheet. (See Figure 1)
Baffle Spacing: 0.16764 meters, 6.6 inches
Tables
Table 1. Film Heat Transfer Coefficient for Shell-and-Tube Heat Exchangers [CRC Handbook,2009].
Table 1 is used for selecting an initial U.
Discussion
Our Initial Design was started with a selection of Stainless Steel 304 material utilizing
two passes with tubes and one pass on shell. Tube size was three quarter outside diameter with
one inch pitch. Tube and shell material was changed during the design process as well as number
of tubes to increase total area and heat transfer to meet the total heat transfer requirements. Shell
and head design from TEMA standards were selected for ease of maintenance and reliability.
Final effectiveness was found to be approximately 60%. A higher effectiveness would be desired
but the design is still affective and meets customer needs.
Conclusions
With a final q within 0.5% of our target q, and an efficiency of about 60% we are
confident that our heat exchanger will meet our customer’s needs. The water going out of the
system cannot be hotter than 80 degrees Fahrenheit, the maximum water temperature we allow in
our design is 77 degrees Fahrenheit. With the calculated maximum temperature for the water
going out we will have a 4% conservative range.
The tubes will be one inch in diameter making two passes having a maximum velocity of 2.73
meters per second giving a design of 9% less than the critical design criteria of 3.0 meters per
second maximum. 460 tubes will be contained within the shell but the minimum requirement is
318, maintenance can easily be conducted and a sufficient amount of tubes may be blocked off in
case corrosion occurs while still maintaining proper flow and heat transfer.
Material similarities between the shell, baffles and tubes will minimize corrosion due to the
materials not being dissimilar metals.
Space constraints were adhered to for total footprint area of the heat exchanger so it can easily fit
into the supplied area by the customer’s requirements of 24feet maximum.
References
Engineering Heat Transfer; Janna, William S. (2011-07-16). Third Edition (Page ii). Taylor and
Francis CRC eBook account. Kindle Edition.
Thermal Conductivity of liquid Ammonia; P. G. VARLASHKIN and J. C. THOMPSON Physics
Department, University of Texas, Austin, Tex.
Thermodynamic Properties of Ammonia; Lester Haar and John S. Gallanger National
measurements Laboratory, National Bureau of Standards, Washington, D.C. 20234
Heat Exchangers Selection, Rating, and Thermal Design; Kakac, S., & Liu, H. (n.d.).
Department of Mechanical Engineering, University of Miami, Coral Gables, Florida: CRC
Press.
Data Sheet
This page is the last page in the report. Following this page is the back cover, which would be a
cover stock.