ME 414 Thermal Fluid System Design Spring 2004

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ME 414 Thermal Fluid System DesignSpring 2004

• Heat Exchanger Design

Presented By Mike Kessler, Matt Sease, Tiffany
Urias
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Objectives

• Design a heat exchanger to support 4 cells each
  containing a 650 hp engine running for 1000 hours
  in a testing facility.
• Minimize
• Weight
• Pressure drops (tube and shell)

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Testing Facility Layout
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Project Summary

• 4-650 hp engines running for 1000 hours
• 80 gpm of coolant per engine
• Work Percentage Breakdown
• 35 Coolant
• 50/50 Mix
• 40 Useful work
• 25 Engine Exhaust

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Coolant Flow Parameters
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Critical Parameters

• Critical Parameters are determined using the
  funnel method.
• This method narrows all the parameters to 5 main
  critical parameters
• Mass flow in shell
• Overall Length of Heat Exchanger
• Shell Inner Diameter
• Tube Outer Diameter
• Tube Pitch (square or triangle)
• All other parameters are fixed

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Analysis

• Using a MatLab Program to (given by instructor)
• Calculate heat transfer of the heat exchanger
  given the parameters entered in.
• Calculate the desired heat transfer to decrease
  the coolant temperature from 235 to 210 F.
• A ratio between the two is then given by the
  program.

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MatLab

• Varied 4 of 5 parameters in MatLab which are
• mass flow rate on the shell (cooling fluid)
• Shell inner diameter
• Tube outer diameter
• Pitch (square or triangular)

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Analysis

• Created another program in MatLab that will
• Incremented Length by 10 cm and run the MatLab
  program with other parameters pre-entered into
  the program and saved certain data points to a
  data file.

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Modifying MatLab

• The data file prints
• Length, mass, dp shell, dp tube, q calc, ratio

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MiniTab

• MiniTab was used to optimize the overall design
• Entered in critical parameters along with their
  values
• Generated a series of combinations
• Those are the parameters that were entered into
  MatLab

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MiniTab File
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Interaction plot

• Interactions between
• mass flow rate of shell
• tube outer diameter
• shell inner diameter
• and pitch

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Interaction Plots

• Interactions between
• Mass flow rate of shell
• Shell inner diameter
• Tube outer diameter
• Pitch

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Interaction Plots

• Interactions between
• Mass flow rate in shell
• Shell inner diameter
• Tube outer diameter
• Pitch

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Main Effects Plot

• Shows how the mass flow rate of shell, shell
  inner diameter, tube outer diameter and pitch
  effect the weight.

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Main Effects Plot

• Shows how the mass flow rate of shell, shell
  inner diameter, tube outer diameter and pitch
  effect the pressure drop in shell.

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Main Effects Plot

• Shows how the mass flow rate of shell, shell
  inner diameter, tube outer diameter and pitch
  effect the pressure drop in the tube.

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Optimizer

• Optimizer in MiniTab was used to optimize the
  design to
• Decrease the overall weight
• Decrease the tube outer diameter
• Increase mass flow
• Increase the shell outer diameter
• Decrease the pressure drop in the shell
• Decrease the tube outer diameter
• Increase the shell outer diameter

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Further Optimization

• In order to further optimize the design
• First fixed the pitch
• triangular
• Tube outer diameter
• 6.35 mm
• Varied 2 parameters
• Mass flow rate
• 10, 12.5, 15 kg/s
• Shell internal diameter
• .2032, .3048, .3874 m

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MiniTab Data
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Overall Main Effect Plot - weight
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Overall Main Effect Plot dp Tube
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Overall Main Effect Plot dp Shell
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Optimize

• From graphs
• Internal shell diameter should increase
• Continually increases number of tubes
• Optimized at .3874 m
• Mass flow
• Optimized at 12.5
• Length
• Optimized at .9 m

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Final Design

• Re-ran MatLab program with fixed
• Length .9 m
• Tube outer diameter 6.35 mm
• Shell inner diameter .3874 m
• Shell mass flow rate 12.5 kg/s
• Pitch triangular at 60

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Results
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Results
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Design Revision

• The heat exchanger that was designed was slightly
  oversized to overcome this a bypass tube will be
  place across the heat exchanger with inline ball
  valve to adjust the flow being bypassed.

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Bypass valve layout
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Recommendation

• More material properties research
• Research real-life geometric restrictions
• Cost of manufacturing
• To optimize design further use coolant
  specification vs. the water to water properties

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Lessons Learned

• How to minimize critical parameters using the
  funnel method
• How to optimize a heat exchanger using the MatLab
  and MiniTab programs
• Heat exchanger design is a balance between heat
  transfer and pressure loss
• Group dynamics

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References

• Professor Toksoy
• Heat Exchangers Selection, Rating, and Thermal
  Design, Kakac, Sadik