Transcript Document
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
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.
Goals
Cool hot fluid by 10º Celsius
Minimize costs by:
Minimizing weight
Minimizing pressure drops
Optimizing tube material
Funnel Effect
7 Effecting Variables
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
1 Factor Runs
Engineering
Judgment
Tube OD
Shell ID
Tube Length
Number Passes
Shell Mass Flow
Rate
Use of Baffles
Baffle Space
3 Critical
Variables
Tube OD
Shell ID
Tube Length
2 Factor
DOE’s
Optimization
Starting Point for Optimization Process
Output Variable
Output Value
Weight
330 kg
ΔP
Shell
6000 Pa
ΔP
Tube
30000 Pa
Heat Transfer Rate
930000 W
Matlab DOE & Minitab DOE Main Effects Plots
7 Variables
Matlab DOE & Minitab DOE Main Effects Plots
3 Variables
Pareto Charts
Minitab Design Optimization
Key Parameter Changes
Pressure Drop (Shell and
Tube)
Number of Tubes
Weight
Final Heat Exchanger Parameters
Input Variable
Input Value
Output Variable
Output Value
Number Tubes
329
Weight
550 kg
Tube Passes
1
ShellΔp
2700 Pa
Tube OD
0.0127 m
TubeΔp
6140 Pa
Tube ID
0.0102 m
Heat Transfer Rate* 948302 W
Tube Length
4.6 m
Results using nominal values based on
Minitab Optimization
Tube Pitch
0.0159 m
*Fouling was taken into consideration
Shell ID
0.3366 m
Baffles
No
Shell Flow Rate
39 kg/s
Conclusion
Chemical was successfully cooled 10 °C
and met all specifications
Cost minimized
Low weight = low material cost
Low pressure drop = lower operational cost
Questions