1. Heat Exchanger Design Optimization
ME 414 Thermal / Fluid System Design
Final Project
Department of Mechanical Engineering
Fall 2005
December 13, 2005
Team Members: Kris Miller
Matt Obras
Andrew Wall
Ben Warner
Professor: John Toksoy

2. Problem Statement
Design a heat exchanger to reduce the temperature of a chemical by 10º Celsius with the following parameters:
Mass flow rate is 80,000 kg/hr.
Fluid enters the heat exchanger at 35º C and should leave at 25º C.
Material properties are approximated as water.
Cooling of the chemical will be achieved by using treated water.
City water is available at 20º C.
Mass flow rate is adjustable.

3. Goals Cool hot fluid by 10º Celsius Minimize costs by:
Minimizing weight
Minimizing pressure drops
Optimizing tube material

4. Funnel Effect 7 Effecting Variables 3 Critical Variables Tube OD
Tube Outer Diameter
Tube Thickness
Shell Inner Diameter
Shell Thickness
Tube Length
Tube Pitch
Number of Tubes
Number of Tube Passes
Shell and Tube Material
Use of Baffles
Baffle Spacing
Baffle Cut
Shell Flow Rate
Fluid Allocation
Type of Flow
Number of Passes
Tube OD
Shell ID
Tube Length
Number Passes
Shell Mass Flow
Rate
Use of Baffles
Baffle Space
Tube OD
Shell ID
Tube Length
1 Factor Runs
Engineering
Judgment
2 Factor
DOE’s
Optimization

5. Starting Point for Optimization Process
Output Variable
Output Value
Weight
330 kg
ΔP Shell
6000 Pa
ΔP Tube
30000 Pa
Heat Transfer Rate W

6. Matlab DOE & Minitab DOE Main Effects Plots 7 Variables

7. Matlab DOE & Minitab DOE Main Effects Plots 3 Variables

8. Pareto Charts

9. Minitab Design Optimization
Key Parameter Changes
Pressure Drop (Shell and Tube)
Number of Tubes
Weight

10. Final Heat Exchanger Parameters
Input Variable
Input Value
Number Tubes
329
Tube Passes 1
Tube OD m
Tube ID m
Tube Length
4.6 m
Tube Pitch m
Shell ID m
Baffles No
Shell Flow Rate
39 kg/s
Output Variable
Output Value
Weight
550 kg
ShellΔp
2700 Pa
TubeΔp
6140 Pa
Heat Transfer Rate* W
Results using nominal values based on Minitab Optimization
*Fouling was taken into consideration

11. Conclusion
Chemical was successfully cooled 10 °C and met all specifications
Cost minimized
Low weight = low material cost
Low pressure drop = lower operational cost

12. Questions