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Heat Exchanger Design
ME 414- FLUID SYSTEMS DESIGN
PROFESSOR: JOHN TOKSOY
SPRING 2009
TEAM
Tyler Laughlin
• Denis Shkurapet
• Ethan Sneed
• Matt Tolentino
• Tyler Turk
•
Objective
 To design a heat exchanger than meets the following
criteria:






Cools liquid from 45 C to 25 C
Must be less than 7 meters in length
Shell diameter is less than 2 meters
Minimize weight of the tube and shell
Minimize pressure drop
Heat transfer ratio of 1
Design Parameters
 # of tubes passed
 Tube outer diameter
 Tube inner diameter
 Material
 Baffles
 Shell thickness
 Shell Material
 Strength factors
 Fluid allocation
 Type of flow (parallel or counter)
Analysis
 Use Minitab and Matlab
 Minitab
 Use to obtain the main effects plots, Pareto charts, and the
response optimizer.
 Matlab
 Use to run analysis of the DOE files and to give us the outputs
of total weight, calculated heat transfer, cost, and pressure
drops.
 DOE allows us to determine the most important variables in
this design.
Results
Variable
Initial value
Final Value
Explanations
Shell fluid
Water
Water
Tube fluid
Chemical (water prop)
Chemical (water prop)
M-dot shell
3.45 kg/s
3.9117 kg/s
Mdot tube
61.11 kg/s
61.11 kg/s
T shell in
20°C
20°C
Given Input
T tube in
45°C
45°C
Given Input
T tube out
25°C
25°C
Given Input
Rf tube in
.00018 m²K/W
.00018 m²K/W
Reference value for water
Rf tube shell side
.00018 m²K/W
.00018 m²K/W
Flow config
Parallel
Parallel
# tube pass
1
1
Reference value for water
DOE - Optimizer suggested
using parallel
The program only allows one
pass
# shell pass
1
1
For minimal weight
Given Input
Given Input
DOE - Optimizer suggested
value
Given value -tube selected
for cleaning
Results
Baffles
No baffles
No baffles
Shell ID
0.3366
0.3366
Shell Th
1.00E-03
1.00E-03
Shell Mat'l
Stainless Steel 304
Stainless Steel 304
Tube Mat'l
Stainless Steel 304
Stainless Steel 304
Nusselt Shell
Dittus Boelter
Dittus Boelter
Nusselt Tube
Gnielinski
Gnielinski
Pressure Corr Shell
Default from textbook
Default from textbook
Pressure Corr Tube
Default from textbook
Default from textbook
Tube OD
6.35e-3 m
6.35E-03
Tube Th
.711e-3 m
4.57E-04
2.00
1.85
90
90
Tube Length
Tube Layout Angle
To reduce weight/pressure
drop
DOE - Optimizer suggested no
change
DOE - Optimizer suggested no
change
Corrosion Resistant/ease of
cleaning
Corrosion Resistant/ease of
cleaning
Most basic correlation
accounts for entrance effects
Only option that was
applicable
Only option that was
applicable
DOE - Optimizer suggested no
change
DOE- Optimizer suggested
value
DOE- Optimizer suggested
value
DOE - Optimizer suggested no
change
Results
Outputs
Initial value
Final Value
Difference
Units
T shell out
353.59°C
318.76°C
34.83
°C
# of tubes
U (Heat Transfer
Coeff.)
1313
1313
0
828.48 W/m2.C
876.97 W/m2.C
-48.49
R value
1.00
0.98
0.02
Weight_He
411.21
350.88 kg
60.33
kg
DP Shell
267.89 Pa
335.11 Pa
-82.99
Pa
DP Tube
45310.96 Pa
29832.58 Pa
15478.38
Pa
W/m2.C
Analysis: 1st DOE
ME 414 Main Effects Plot: DP Tube
ME 414 Main Effects Plot: Weight_HE
F low
M dot
F low
Tube Length
M dot
Tube Length
1000000
700
500000
500
0
300
P arallel
C ounter
2.5875
Tube th
4.3125
1.5
S hew ll ID
C ounter
2.5875
Tube th
S hell Th
4.3125
1.5
2.5
S hew ll ID
S hell Th
1000000
Mean
700
Mean
P arallel
2.5
500
500000
0
300
0.000533
0.001250
0.25245
0.42075
0.0007500
0.000533
0.0012875
700
1000000
500
500000
300
0.00476
0.001250
0.42075
0.0007500
0.0012875
0
0.00793
0.00476
0.00793
ME 414 Main Effects Plot: DP Shell
F low
1000
0.25245
Tube O D
Tube O D
ME 414 Main Effects Plot: Q Calc
M dot
Tube Length
F low
10000000
M dot
Tube Length
7500000
500
5000000
0
P arallel
2.5875
4.3125
1.5
S hew ll ID
2.5
P arallel
C ounter
S hell Th
500
2.5875
Tube th
10000000
Mean
Mean
C ounter
Tube th
1000
4.3125
1.5
S hew ll ID
2.5
S hell Th
7500000
5000000
0
0.000533
0.001250
0.25245
0.42075
0.0007500
0.0012875
0.000533
Tube O D
1000
0.001250
Tube O D
10000000
7500000
500
5000000
0
0.00476
0.00793
0.00476
0.00793
0.25245
0.42075
0.0007500
0.0012875
Analysis: Pareto Charts 1st DOE
Pareto Chart of the Standardized Effects
Pareto Chart of the Standardized Effects
(response is Weight, Alpha = 0.05)
(response is DP Shell, Alpha = 0.05)
2
2.0
F actor
A
B
C
D
A
B
B
A
AC
AB
Term
Term
C
N ame
F low
M dot
Tube Length
Tube th
D
AB
AD
F actor
A
B
C
N ame
F low
M dot
Tube Length
F actor
B
C
N ame
M dot
T ube Length
C
BC
BD
AC
ABD
0
200000
400000
600000
800000
1000000
Standardized Effect
1200000
0
1400000 1600000
50
Pareto Chart of the Standardized Effects
100
Standardized Effect
150
200
Pareto Chart of the Standardized Effects
(response is DP Tube, Alpha = 0.05)
(response is Q Calc, Alpha = 0.05)
1.98
1.98
C
Term
Term
Tube Length
B
Flow
BC
0
2
4
6
8
Standardized Effect
10
12
14
0
10
20
30
40
Standardized Effect
50
60
Analysis: 1st Optimization
Minitab solved for a local solution.
The starting values were changed
multiple times until Minitab found a
new, more optimal solution.
Analysis: 2nd DOE
ME 414 Main Effects Plot Optimization 2: Q Calc
F low
M dot
ME 414 Main Effects Plot Optimization 2: DP Tube
Tube Length
F low
10000000
150000
7500000
100000
P arallel
C ounter
Tube Thick
2.5875
4.3125
1.5
2.5
S hell ID
P arallel
S hell Thick
C ounter
2.5875
4.3125
Tube Thick
1.5
2.5
S hell ID
S hell Thick
150000
10000000
Mean
Mean
Tube Length
50000
5000000
7500000
5000000
0.0003430
0.0005713
Tube O D
0.25245
0.42075
0.0007500
100000
50000
0.0012875
0.0003430
10000000
7500000
100000
5000000
50000
0.00793
0.00476
ME 414 Main Effects Plot Optimization 2: DP Shell
F low
1000
0.0005713
0.25245
0.42075
0.0007500
0.0012875
Tube O D
150000
0.00476
M dot
0.00793
ME 414 Main Effects Plot: Weight_HE
F low
Tube Length
M dot
Tube Length
700
500
500
300
0
P arallel
C ounter
2.5875
Tube Thick
1000
4.3125
S hell ID
1.5
P arallel
2.5
C ounter
2.5875
Tube th
S hell Thick
4.3125
1.5
S hew ll ID
2.5
S hell Th
700
Mean
Mean
M dot
500
500
300
0
0.0003430
0.0005713
0.25245
0.42075
0.0007500
0.0012875
0.000533
0.001250
Tube O D
Tube O D
1000
700
500
500
300
0
0.00476
0.00793
0.00476
0.00793
0.25245
0.42075
0.0007500
0.0012875
Analysis: 2nd Optimization
Starting values of the optimization were varied with no
improvement in performance.
Conclusions: Damn near perfect!
 Heat Transfer Coeff :
 R-value:
 Number of tubes:
 Shell Pressure Loss:
 Tube Pressure Loss:
 Weight of Heat Exchanger:
876.97 W/m2.C
0.98
1313
335.11 Pa
29832.58 Pa
350.88 kg
Conclusions: Recommendations
 Could be further optimized if Tube Thickness was
decreased
 Resulting in:
Lower weight - decrease of 51.93 kg
 Lower Tube pressure loss - decrease of 6703.1 Pa
 No significant loss of R-value

 A smaller tube is not commercially available
 Possibly achieve greater performance at a greater
price
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