1. ME 414 Thermal / Fluid System Design Heat Exchanger Project Professor: John Toksoy 12/13/05 Team Members: Chester Bennett Wilton Green Scott Guttman Nick Miller Department of Mechanical Engineering Fall 2005 Final Project

2. Project Statement Challenges Challenge of the project to use an oriented and rational process to lead to a justified final design. Challenge of designing and optimizing a heat exchanger to particular qualifications Qualifications: Tube side fluid is available at 20 C Tube side Mass flow rate is 22.22 kg/s Maximum tube length of 7 meters Maximum shell diameter of 2 meters Cool tube side fluid from 35 o C to 25 o C Tube and Shell fluid properties ~ Water

3. Objective Objective Definition: – Obtain a heat transfer ratio of 1 – Minimize pressure drop – Minimize weight – Minimize cost Achieving Objective: Design Plan – Determine potential key parameters – Reduce key parameters to as few as possible prior to optimization using Matlab and Minitab – Optimize using the DOE in Matlab and analyzing the results in Minitab

4. Potential Key Parameters Shell Mass Flow Rate Shell Inner Diameter Shell Thickness Shell Material Type of Flow Pitch Type Tube Length Tube Outer Diameter Tube Thickness Tube Material Tube Layout Angle # Tube Passes Consideration Criterion: Heat Transfer, Pressure Drops, Weight, Cost

5. Non-potential Parameter Judgements Pitch Type – Square Pitch Tube Layout – 90 degree layout Flow Type – Counter Flow Baffle Design – Provides turbulence to reduce fouling

6. Shell Material Selection Material Considerations – Weight – Heat Transfer Rates – Strength and Stress – Corrosion Resistance – Cost (Initial and Maintenance) Stainless Steel Carbon Steel Stainless Steel AISI 304 Pure Bronze Pure Copper Pure Aluminum Decision rational: Aluminum is light weight Aluminum is a good heat conductor Aluminum is compatible with water Aluminum low yield stress not a factor Aluminum’s benefits justify the costs

7. Design of Experiment Using 6 key parameters – Tube OD – Tube Length – Shell ID – Mass Flow Rate – Tube Material – Tube Thickness Determine 15% range of chosen parameters Incorporate into DOE program in MATLAB Export output file to Minitab Obtain Main Effects Plots

8. Main Effects Plots

9. Variable Reduction Establish material Establish tube thickness Establish 4 key parameters – Tube OD – Tube Length – Shell ID – Mass Flow Rate Determine 15% range of chosen parameters Incorporate into DOE program in MATLAB Export output file to Minitab Obtain Main Effects Plots - Aluminum -.001254 m

10. Main Effects Plots for 4 Key Parameters

11. Original Optimization OutputGoalLowerTargetUpper WeightMinimize-410652 Dp ShellMinimize-31005666 Dp TubeMinimize-850017762 QTarget7162829285001094141 Optimization Results Chart Optimization Setup Optimization Results OutputValue Weight481.89 Dp Shell3371 Dp Tube9045 Q908462 ratio1.02

12. Optimization Considerations Standardizing parameters to minimize costs Tube OD Shell ID Varying parameter’s current optimum value (red line) Effect: Increasing or decreasing Output values according to slope Effect: Increasing or decreasing Output desirability value Goal: To keep standardized parameters Goal: To maintain heat transfer ratio of 1 (desirability of.7-.8) Goal: Minimize Outputs considering importance of Outputs Sacrificing Weight or Pressure Drop -.0127 meters -.2540 meters,.3048 meters, or.3366 meters

13. Optimization Results Option 1 Sacrifice weight for pressure drops Option 2 Sacrifice tube pressure drop for weight Option 3 Sacrifice both pressure drops for weight ParameterValueOutputValue Tube OD0.0127Weight528.21 Shell ID0.3366Dp Shell3386 Tube Length4.2136Dp Tube5741 Shell Flow Rate43.8668Q925716 Ratio1.00 Option 1 ParameterValueOutputValue Tube OD0.0127Weight412.26 Shell ID0.254Dp Shell4977 Tube Length5.609Dp Tube19725 Shell Flow Rate36.1886Q926646 Ratio1.00 Option 2 ParameterValueOutputValue Tube OD0.0127Weight374.96 Shell ID0.254Dp Shell6854 Tube Length5.1013Dp Tube18322 Shell Flow Rate43.1577Q931929 Ratio1.00 Option 3

14. Final Project Conclusion Option One Decision Criteria Equal heat transfer ratios among all Options Safe fouling velocity in tube Standardized tube and shell sizes Trade-offs in relative percentage gains and losses Precedence to pressure http://www.greenheck.com/technical/files/Product_guide/images/pag_fig5.gif

15. From Alpha to Omega Alpha ParameterAlpha Value Shell Mass Flow Rate38.8889 Tube Mass Flow Rate22.2222 Flow TypeCounter Tube Passes1 Shell Passes1 BafflesNone Shell ID0.3048 Shell Thickness4.00E-03 Shell MaterialAluminum Tube MaterialAluminum Shell Nusselt2 Tube Nusselt4 Tube OD0.0127 Tube Thickness0.001245 Tube Length4.8000 Tube PitchSquare Tube Layout90 Omega ParameterOmega Value Shell Mass Flow Rate43.8668 Tube Mass Flow Rate22.2222 Flow TypeCounter Tube Passes1 Shell Passes1 BafflesNone Shell ID0.3366 Shell Thickness4.00E-03 Shell MaterialAluminum Tube MaterialAluminum Shell Nusselt2 Tube Nusselt4 Tube OD0.0127 Tube Thickness0.001245 Tube Length4.2136 Tube PitchSquare Tube Layout90 OutputValue Weight528.21 Dp Shell3386 Dp Tube5741 Q925716 Ratio1.00 Heat Exchanger Option 1

16. Questions