ME 414 Design Project

Report
ME 414 Design Project
Heat Exchanger Design
Created and Designed by:
Michael Stark
Joshua Keith
Billy Burdette
Brandon Mullen
Joseph Listerman
Project Goals
 Design Heat Exchanger
 Create a light weight heat exchanger
 Heat exchange must be as efficient as possible
 Cost must be kept low as possible
 The size of the heat exchanger must be under design constraint
Project Guidelines
 During the process of a liquid chemical product, its temperature needs
to be reduced by 20 degrees Celsius.
 Mass flow rate is 220,000 kg/hr
 Fluid enters the heat exchanger at 45 C and should leave at 25 C
 Material properties of this chemical product can be approximated as water
 Cooling of the chemical product will be achieved by using treated city
water
 City water is available at 20 C
 Mass flow rate is adjustable and one of the design parameters to be selected
 Exit temperature of city water from the heat exchanger is a function of the selected mass
flow rate
Professor Toksoy
Project Optimization
 Must cool the chemical from 45 C to 25 C
 Heat exchanger length can not exceed 7 meters
 Heat exchanger shell diameter can not exceed 2 meters
 Minimize heat exchanger shell and tube weight hence the cost
 Minimize heat exchanger pressure drop
Professor Toksoy
Heat Exchanger Design Inputs
for MATLAB
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Chemical to be cooled was set as Shell side liquid
Mass flow rate of cooling water = 220 kg/sec
Shell ID = .889 m
Shell thickness = 5 mm
Tube OD = 6.35 mm
Tube thickness = .457 mm
Tube Length = 2.88 m
Baffle space = .6 m
Helical Baffles
Counter flow
One shell pass and one tube pass
Aluminum was used for both shell and tube materials
Gnielinski equation used for tube side Nusselt correlation
Square tube pitch
Nusselt Correlation
D.O.E. Run 1
Main Effects Plot for Weight
Main Effects Plot for q_Calc
Data Means
Data Means
mdot Shell
mdot Shell
Tube Length
1600000
1400000
4000
1200000
3000
2000
800000
200
240
2
4
Shell
Mean
1000000
Mean
Tube Length
5000
1000
200
240
2
4
Shell
1600000
5000
1400000
4000
1200000
3000
2000
1000000
1000
800000
0.5
0.5
1.5
Main Effects Plot for DP_Shell
Main Effects Plot for DP_Tube
Data Means
Data Means
mdot Shell
80000
1.5
mdot Shell
Tube Length
Tube Length
120000
60000
100000
40000
80000
200
240
Shell
80000
2
4
Mean
Mean
20000
200
240
Shell
120000
60000
100000
40000
20000
80000
0.5
1.5
0.5
1.5
2
4
D.O.E. Run 2
Main Effects Plot for q_Calc
Main Effects Plot for Weight
Data Means
5600000
Tube Th
Baffles Space
2500
5400000
2450
5200000
2400
5000000
2350
0.3
0.8
0.000457
0.000711
Baffle Cut
5600000
0.3
5400000
2450
5200000
2400
5000000
2350
0.8
0.000457
0.000711
Baffle Cut
2500
2300
4800000
0.1
0.5
0.1
0.5
Main Effects Plot for DP_Tube
Main Effects Plot for DP_Shell
Data Means
Data Means
Baffles Space
10000
Tube Th
8000
18000
6000
16000
4000
14000
2000
0.3
0.8
Baffle Cut
10000
0.000457
Baffles Space
20000
0.000711
Mean
Mean
Tube Th
2300
4800000
Mean
Mean
Data Means
Baffles Space
12000
0.3
8000
18000
6000
16000
4000
14000
0.8
Baffle Cut
20000
2000
Tube Th
12000
0.1
0.5
0.1
0.5
0.000457
0.000711
Final D.O.E.
Main Effects Plot for DP_Tube
Main Effects Plot for q_Calc
Data Means
Data Means
Tube Length
Shell ID
7000000
9000
6000000
6000
5000000
3000
4000000
2
4
0.889
1.500
Tube OD
8000000
0
2
4
0.889
1.500
Tube OD
12000
7000000
9000
6000000
6000
5000000
3000
0
4000000
0.00635
0.00635
0.01270
0.01270
Main Effects Plot for Weight
Main Effects Plot for DP_Shell
Data Means
Data Means
Tube Length
Tube Length
Shell ID
2000
6000
1750
5000
1500
Shell ID
4000
1250
1000
3000
2
4
Tube OD
0.889
1.500
Mean
Mean
Shell ID
12000
Mean
Mean
8000000
Tube Length
2
2000
6000
1750
5000
1500
4
Tube OD
4000
1250
3000
1000
0.00635
0.01270
0.00635
0.01270
0.889
1.500
Factorial Design Analysis – Heat Rate
Pareto Chart of the Standardized Effects
(response is q_Calc, Alpha = 0.05)
12.7
F actor
A
B
C
A
 Tube length has the largest
Term
C
AC
B
AB
BC
0
100
200
Standardized Effect
300
400
Normal Plot of the Standardized Effects
(response is q_Calc, Alpha = 0.05)
99
Effect Ty pe
Not Significant
Significant
95
90
C
70
60
50
40
AC
30
AB
20
10
F actor
A
B
C
A
80
Percent
affect on the heat rate.
 Shell ID has the smallest
relative affect on heat rate.
 Shell ID had a negative affect
on heat rate.
 This was a result of more
tubes decreasing the
velocity in the tube.
 The result is laminar flow
inside the tube.
N ame
T ube Length
S hell ID
T ube O D
B
5
1
0
100
200
Standardized Effect
300
400
N ame
T ube Length
S hell ID
T ube O D
Factorial Design Analysis - ∆P Tube
 We can see that tube length has the largest affect on tube side pressure
drop.
 Shell ID has no affect on tube pressure drop.
 We expected tube OD to have a larger affect on tube side pressure drop.
Pareto Chart of the Effects
(response is DP_Tube, Alpha = 0.05)
F actor
A
B
C
C
Term
A
AC
B
BC
AB
0
2000
4000
6000
8000
Effect
10000
12000
14000
N ame
Tube Length
S hell ID
Tube O D
Factorial Design Analysis - ∆P Shell
 Shell ID had the largest
affect on shell side
pressure drop.
 The affect of tube OD on
the pressure drop was
surprising.
the 60° triangular pitch
tube arrangement.
 As tube OD grows larger
there is more pressure
drop in the shell.
(response is DP_Shell, Alpha = 0.05)
12.71
F actor
A
B
C
B
C
Term
 We attribute this affect to
Pareto Chart of the Standardized Effects
A
BC
AB
AC
0
2
4
6
8
10
Standardized Effect
12
14
N ame
Tube Length
S hell ID
Tube O D
Factorial Design Analysis – HE Weight
 The shell inside
diameter has the largest
affect on weight.
Pareto Chart of the Effects
(response is Weight, Alpha = 0.05)
 The larger the shell
 Because tube length
determines the length
of the heat exchanger, it
too has a large affect on
heat exchanger weight.
B
A
Term
diameter the more
tubes we could fit
inside, thus increasing
weight.
F actor
A
B
C
AB
C
AC
BC
0
1000
2000
Effect
3000
4000
N ame
Tube Length
S hell ID
Tube O D
Design Optimization - 1

The design optimized to our original
design.

We expected our final tube diameter to
be 6.35 mm with a mass flow rate of 220
kg/s.
 Optimal Tube OD was 8.3mm

The tube length was longer than our
original design called for, which was a
result of maximizing the q calculated.

We set target values for the shell and
tube side pressure drops.

We set a target range for total weight
between 900-1100 kg.
Design Optimization - 2
New
High
D
Cur
1.0000 Low
Composite
Desirability
1.0000
Tube Len
4.0
[2.6263]
2.0
Shell ID
1.50
[0.8890]
0.8890
Tube OD
0.0127
[0.0096]
0.0063

The design optimized to our original design.

We expected our final tube diameter to be
6.35 mm with a mass flow rate of 220 kg/s.
 Optimal Tube OD was 8.3mm, adjusted it
to 9.525 mm to coincide with standard
tube dimensions.

The tube length was longer than our original
design called for, which was a result of
maximizing the q calculated.

We set target values for the shell and tube side
pressure drops.

We set a target range for total weight between
900-1100 kg.
Weight
Minimum
y = 2288.8141
d = 1.0000
DP_Shell
Minimum
y = 1805.0741
d = 1.0000
DP_Tube
Minimum
y = 5865.8838
d = 1.0000
q_Calc
Maximum
y = 5.454E+06
d = 1.0000
Heat Exchanger Design Output from
MATLAB
Matlab Program Improvements
 Create program checks in order to eliminate unrealistic
designs.
 If multiple tube passes are used with parallel flow it is possible
to calculate a LMTD_CF that is an imaginary number.
 Provide the operator more detailed information regarding
the Nusselt correlations.
Cost Summary
 Heat Exchanger Dry Weight
 730 Kg
 Heat Exchanger & Fluid Weight
 2287 Kg
 Cost
 OnlineMetals.com
 $37.00 per 8ft length of aluminum tubing
 Total estimated aluminum tubing cost $337,000.00
 $11.00 per 8ft length of mild steel tubing
 Total estimated mild steel tubing cost $100,000.00
 Instillation and Manufacturing

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