1. By: Brittany Watton & Jeff Philippart
Heat Exchanger Design
By: Brittany Watton & Jeff Philippart

2. Design Criteria
Design a heat exchanger to dissipate 1MW of thermal energy for the High Performance Computer Center.
It must be less than 20 ft long and compact. The current piping has a diameter of 14 inches
The potable water has a temp of 57 degrees exiting the reservoir and cannot change by more than 3 degrees. It flows at 10^6 gal/day. Liquid to disperse heat is at 90 to 100 degrees F and flows at 5*10^6 gal/day.
Pressure drop should be minimized.

3. Design Considerations
Fluid Choice- Water is the best choice because of its high heat capacity and thermal capacity, it is also cost effective and easily accessible
Tube material- Copper was chosen for its thermal performance and corrosion resistance
The Pitch Ratio was chosen to be 1.25, this makes the space between tubes .25 times the tube size.
The number of baffles was chosen to be 4.

4. MatLab Code Description
Three parameters were varied to achieve 18 independent results.
1- The arrangement was altered, the script prompts the user to select a triangular or square layout for the tubes.
2- The number of passes is then selected as either 1, 2 or 3
3- The last option is pipe diameter; .5”, .75” and 1” are all standard sizes which make them easier to purchase. One of the above is chosen as the last parameter.

5. Cost Analysis
Triangular Layout
pipe size (in.)
cost per pipe
# pipes
total cost 1
$108.50
 105
 $11,392.5
0.75
$70.00
 188
$13,160.0 
0.5
$43.70
 423
 $18,485.1
Square Layout
pipe size (in.)
cost per pipe
# pipes
total cost 1
$108.50 91
$9,873.50
0.75
$70.00
162
$11,340.00
0.5
$43.70
366
$15,994.20
This does not show the total cost, it shows the relationship between the diameter of the pipes and the approximated total cost for the pipes. The smaller the diameter the more pipes that can fit in the space.

6. Results A smaller tube size results in a smaller pressure drop
Square Arrangement (1 pass)
Pipe Diam. (in.)
# of tubes
effectiveness
q_max
press. Drop hot (kpa)
press. Drop cold
total press. Drop
0.5
366
0.2473
4.043
0.547
2.719
3.2665
0.75
162
0.1932
5.1757
9.7286
1.6452
11.374 1 91
0.1254
7.9715
218.71
1.55
219.87
Square Arrangement (2 passes)
press. Drop hot
354
0.1841
5.4324
4.1
6.8192
157
0.1234
8.1039
73.835
75.48 88
0.0701
1675.6
1.155
1676.8
Triangular Arrangement (1 pass)
423
0.4987
2.005
4.0225
4.447
188
7.412
2.426
9.8839
105
168.1
1.699
169.86
Triangular Arrangement (2 passes)
409
3.148
4.0255
7.174
182
56.179
2.4264
58.605
102
127.41
1.6992
127.58
One pass had a lower pressure drop than 2 passes
The triangular arrangement also reduced the pressure drop

7. Recommendations
For the lowest pressure drop the optimal design from the results devised would point to a square arrangement of tubes with diameters of .5” and a single pass.
This would be the second most costly option but it fits within the design parameters and the efficiency would reduce the cost of use.
This design is conducive for easy cleaning, the components can be cleaned with a brush and chemically

8. Supplier