ME414 Spring 2006 Design Project 2 Heat Exchanger

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ME414Spring 2006Design Project 2Heat Exchanger

• Ugo Anyoarah
• Osinanna Okonkwo
• Vinay Prisad
• Daniel Reed

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Introduction

• Introduction
• Project Definition
• Design Optimization Goals
• First Design Pass
• Second Design Pass
• Other Factors
• Design Results

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Project Definition

• During the make of a liquid chemical product, its
  temperature needs to be reduced by 10 degrees
  Celsius.
• Mass flow rate is 80,000 kg/hr
• Fluid enters the heat exchanger at 35 C and
  should leave at 25 C
• Material properties of this chemical product can
  be approximated as water
• Cooling of the chemical product will be achieved
  by using treated city water
• City water is available at 20 C
• Mass flow rate is adjustable and one of the
  design parameters to be selected
• Exit temperature of city water from the heat
  exchanger is a function of the selected mass flow
  rate

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Design Optimization Goals

• Must cool the chemical from 35 C to 25 C
• Heat exchanger length can not exceed 7 m
• Heat exchanger shell diameter can not exceed 2 m
• Minimize heat exchanger shell and tube weight
  hence the cost
• Minimize heat exchanger pressure drop

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First Design Pass

• Matlab Variables
• 4 variables
• Tube_OD (6.350 25.4)e-3 meters
• Shell_ID (.8 2) meters
• Tube_Len (4 7) meters
• N_tube (40 100)
• 7 levels
• Gives 74 2401 runs

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First Design Pass

• Matlab Variables
• Tube and Shell Material set to Aluminum
• Consistent expansion between shell tubes.
• Maximum heat transfer
• Corrosion Resistance (chemical similar to H20)
• Tube pass set to two (2)
• Most space efficient
• Baffle Space set to 0.1048 m
• Baffle Cut set to 0.3750 m
• City water flow rate set to 38.8889 Kg/Sec

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First Design Pass

• Matlab Results
• Weight 2069.17 22415.9
• DP Shell 335149 6364756
• DP Tube 17701.66 4.26e11
• Q Calc 107043.7 919867.5
• 2401 runs AAARRRGGGHHH!!!!!

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First Design Pass - MiniTab Results
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First Design Pass

• Findings
• MiniTab will not do Pareto charts for systems
  with more than 2 levels.
• Higher levels ( gt4) are beneficial for
  identifying linear regions and critical areas.

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Second Design Pass

• Used Excel to find variable combinations with
  Qcalc/Qdes 1 /-10
• 12 combinations met criteria
• Used the max and min in 2nd iteration of Matlab
  (2 level)

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Second Design Pass

• Matlab Variables
• 4 variables
• Tube_OD (9.535 25.4)e-3 meters
• Shell_ID (.8 1) meters
• Tube_Len (6.5 7) meters
• N_tube (90 100)
• 2 levels
• Gives 24 16 runs

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Second Design Pass

• Matlab Results
• Weight 3444 5773
• DP Shell 122279 3933472
• DP Tube 24799 41293392
• Q Calc 844667 919867
• 16 runs MMM! (Much more manageable)

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Second Design Pass - MiniTab Results
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Second Design Pass - Optimizer
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Second Design Pass - Optimizer
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Second Design Pass

• Check W/ Matlab
• Number of Tubes N 100.00
• Number of Passes 2.00
• Tubes OD OD 0.0191 m
• Tubes ID ID 0.0135 m
• Tube Length L 6.7500 m
• Tube Pitch PT 0.0238 m
• Shell ID 0.9000 m
• Baffle Space 0.1048 m
• Number of Baffles 63.0000 m
• Desired Heat Transfer Rate 928501.84 W
• Calculated Heat Transfer Rate 843364.57 W
• Difference 85137.28 W
• Desired-to-Calculated Ratio 1.10
• Shell Side Delta-P 1517783.93 Pa
• Tube Side Delta-P 138509.45 Pa
• Total HE Weight 4550.87 kg

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Second Design Pass

• Fouling Factor
• Increased tube number to account for fouling
• 116 tubes required for Q/q1
• 135 tubes for Q/q0.91
• DP Shell Unchanged
• DP Tube 79943.83 Pa
• Weight 4607.82 Kg

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Other Factors

• Full Factorial desirable
• City Water Flow Rate
• Baffle Spacing
• Baffle Cut Height
• Tube Pitch
• Tube Layout Angle
• Yields 12 factors
• Even 2 levels is long 4096 data points

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Design Results

• Length 6.5m
• Shell ID 1m
• Tube OD 19.1mm
• Tube Length 6.75m
• Number of Tubes 135

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