Transcript Problem Statement - Engineering and Technology IUPUI

Shell and Tube Heat Exchanger
ME 414: Thermal Fluids
Frank Faulkenberg
Jimmy Huser
John Snodgrass
Eric Bush
David Giles
Problem Statement
Design a heat exchanger to meet the
customer requirements for heat
transfer and maximum dimensions,
while optimizing the weight and
pressure losses in both the tube and
shell sides.
Project Definition

Chemical Specifications:
• Temperature must be reduced from 40°C to
25°C
• Mass flow rate is 120,000 kg/hr
• Material properties closely approximate that of
water

Cooling Water Specifications:
• Treated city water at 20°C
• Mass flow rate is not fixed
• Exit temperature is function of design
Customer Requirements





Must cool the chemical from 40 C to 25 C
Heat exchanger length can not exceed 7m
Heat exchanger shell diameter can not
exceed 2m
Minimize heat exchanger shell and tube
weight hence the cost
Minimize heat exchanger pressure drop
Analysis

Matlab
Used to run code
that takes the
input variables that
affect exchanger
performance and
returns numerical
values for the
performance of the
exchanger

Minitab
Used to statistically
analyze the results
from Matlab to
narrow down the
input variables to
those that have the
greatest affect of
exchanger
performance.
First Trial

Total heat exchanger weight =
4384.68 kg

Desired Heat Transfer Rate =
2088969 W

Calculated Heat Transfer Rate =
2084742 W

Difference =

Desired-to-Calculated Ratio

Shell Side Delta-P =
9875.34 Pa

Tube Side Delta-P =
134.48 Pa
4227.48 W
=
1.00
Analyzing data

Good
• Light in weight
• Good pressure drops
• Achieved desired-to-calculated ratio
Analyzing data

Bad
• Further inspection shows that this design is
impossible.
Inlet (°C)
Outlet (°C)
Tube
40
25
Shell
20
32
•Shell side outlet cannot be greater than the tube side outlet
for a parallel heat exchanger.
•For parallel flow, a shell mass flow rate of ~400000 kg/hr
must be used to satisfy this condition
Second Trial
Parallel flow
 No baffles
 About 4 meters in length

Analyzing Data
Good:
 Yielded very low weight
 Very low pressure drops
 Desired heat transfer
Bad:
 Impossible design in reality
 Structurally unsound, tubes would sag
Critical Parameter Flow Down

14 parameters

7 factor DOE

4 factor DOE
Initial Parameters







Tube length
Tube diameter
(OD)
Shell diameter (ID)
Mass Flow Rate of
cooling water
Pipe layout
Baffle Spacing
Shell material







Tube material
Shell thickness
Tube thickness
Flow configuration
(counter, parallel)
Pipe layout angle
Number of Tubes
Tube Pitch
1st DOE







Tube length
Tube diameter
(OD)
Shell diameter (ID)
Mass Flow Rate of
cooling water
Pipe layout
Baffle Spacing
Shell material
7 factor MEPs
Main Effects Plot (data means) for Q_7
Tube_O D_7
S hell_ID_7
tube_len_7
1800000
1500000
Mean of Q_7
1200000
0.010795
0.014605
mdot_shell_7
0.71247
0.96393
sqr_tri_7
5.2275
7.0725
baffle_space_7
1800000
1500000
1200000
28.333
38.333
shell_mat_7
1800000
1500000
1200000
2
21
0
1
0.402
0.600
2nd DOE




Tube length
Tube diameter
(OD)
Shell diameter (ID)
Mass Flow Rate of
cooling water
4 factor MEPs
Main Effects Plot (data means) for Q
Tube_OD
Shell_ID
1800000
1650000
1500000
Mean of Q
1350000
1200000
0.010795
0.014605
Tube_Length
0.71247
0.96393
mdot_shell
1800000
1650000
1500000
1350000
1200000
5.2275
7.0725
28.333
38.333
4 factor MEPs
Main Effects Plot (data means) for DP_shell
Tube_OD
Shell_ID
12000
Mean of DP_shell
10000
8000
0.010795
0.014605
Tube_Length
0.71247
0.96393
mdot_shell
12000
10000
8000
5.2275
7.0725
28.333
38.333
4 factor MEPs
Main Effects Plot (data means) for weight
Tube_OD
7000
Shell_ID
6000
Mean of weight
5000
4000
0.010795
0.014605
0.71247
Tube_Length
7000
0.96393
mdot_shell
6000
5000
4000
5.2275
7.0725
28.333
38.333
4 factor MEPs
Main Effects Plot (data means) for DP_tube
Tube_OD
Shell_ID
1000
Mean of DP_tube
800
600
400
0.010795
0.014605
Tube_Length
0.71247
0.96393
mdot_shell
1000
800
600
400
5.2275
7.0725
28.333
38.333
4-factor Interaction Plots
Interaction Plot (data means) for DP_shell
0.71247
0.96393
5.2275
7.0725
28.333
38.333
15000
10000
Tube_OD
5000
15000
10000
Shell_ID
5000
15000
10000
Tube_Length
5000
mdot_shell
Tube_OD
0.010795
0.014605
Shell_ID
0.71247
0.96393
Tube_Length
5.2275
7.0725
Pareto Charts
Pareto Chart of the Effects
(response is DP_shell, Alpha = .10)
1202
F actor
A
B
C
D
D
A
C
B
AD
Term
CD
BD
AC
AB
BC
A CD
ABD
BCD
ABC
A BCD
0
1000
Lenth's PSE = 596.751
2000
3000
Effect
4000
5000
N ame
Tube_O D
S hell_ID
Tube_Length
mdot_shell
Final Design
1 shell pass
1 tube pass
Shell material = Al
Tube material = Al
Mdot_shell = 120000 kg/hr
Mdot_tube = 120000 kg/hr
Shell_ID = 0.8382 m
Tube_OD = 12.7 mm
Shell_th = 19.05 mm
Tube_th = 20 BWG
Baffle spacing= 0.6*Shell_ID Tube pitch = 1.4*Tube_OD
Baffle cut = 25%
30° Triangular layout
Expected Performance

Total heat exchanger weight
4868 kg

Desired Heat Transfer Rate
2088969 W

Calculated Heat Transfer Rate
2095309 W

Difference
-6340 W

Desired-to-Calculated Ratio
1.00

Shell Side Delta-P
9228 Pa

Tube Side Delta-P
556 Pa
References
[1] Jones, Luke. “Minitab tutorial.”
[2] Toksoy, John. “Heat Exchanger Project –
fall 2006.”
[3] Toksoy, John. “TFD-HE4 Log Mean
Temperature Difference.” fall 2006