ME414ME414Spring 2006Spring 2006

Design Project 2Design Project 2Heat ExchangerHeat Exchanger

Ugo Anyoarah Ugo Anyoarah

Osinanna OkonkwoOsinanna Okonkwo

Vinay Prisad Vinay Prisad

Daniel ReedDaniel Reed

IntroductionIntroduction• IntroductionIntroduction

• Project DefinitionProject Definition– Design Optimization GoalsDesign Optimization Goals

• First Design PassFirst Design Pass

• Second Design PassSecond Design Pass

• Other FactorsOther Factors

• Design ResultsDesign Results

Project DefinitionProject Definition• During the make of a liquid chemical product, its During the make of a liquid chemical product, its

temperature needs to be reduced by 10 degrees temperature needs to be reduced by 10 degrees Celsius. Celsius. – Mass flow rate is 80,000 kg/hrMass flow rate is 80,000 kg/hr– Fluid enters the heat exchanger at 35 C and should leave at Fluid enters the heat exchanger at 35 C and should leave at

25 C25 C– Material properties of this chemical product can be Material properties of this chemical product can be

approximated as waterapproximated as water

• Cooling of the chemical product will be achieved by Cooling of the chemical product will be achieved by using treated city waterusing treated city water– City water is available at 20 CCity water is available at 20 C– Mass flow rate is adjustable and one of the design Mass flow rate is adjustable and one of the design

parameters to be selectedparameters to be selected– Exit temperature of city water from the heat exchanger is a Exit temperature of city water from the heat exchanger is a

function of the selected mass flow ratefunction of the selected mass flow rate

Design Optimization GoalsDesign Optimization Goals

• Must cool the chemical from 35 C to 25 Must cool the chemical from 35 C to 25 CC

• Heat exchanger length can not exceed Heat exchanger length can not exceed 7 m7 m

• Heat exchanger shell diameter can not Heat exchanger shell diameter can not exceed 2 mexceed 2 m

• Minimize heat exchanger shell and tube Minimize heat exchanger shell and tube weight hence the costweight hence the cost

• Minimize heat exchanger pressure dropMinimize heat exchanger pressure drop

First Design PassFirst Design Pass

• Matlab VariablesMatlab Variables– 4 variables4 variables

•Tube_ODTube_OD (6.350 – 25.4)e-3 meters(6.350 – 25.4)e-3 meters

•Shell_IDShell_ID (.8 – 2) meters(.8 – 2) meters

•Tube_LenTube_Len (4 – 7) meters(4 – 7) meters

•N_tubeN_tube (40 – 100)(40 – 100)

– 7 levels7 levels•Gives 7^4 = 2401 runsGives 7^4 = 2401 runs

First Design PassFirst Design Pass

• Matlab VariablesMatlab Variables– Tube and Shell Material set to AluminumTube and Shell Material set to Aluminum

• Consistent expansion between shell & tubes.Consistent expansion between shell & tubes.

•Maximum heat transferMaximum heat transfer

•Corrosion Resistance (chemical similar to HCorrosion Resistance (chemical similar to H220)0)

– Tube pass set to two (2)Tube pass set to two (2)•Most space efficientMost space efficient

– Baffle Space set to 0.1048 m– Baffle Cut set to 0.3750 m

– City water flow rate set to City water flow rate set to 38.8889 Kg/Sec

First Design PassFirst Design Pass

• Matlab ResultsMatlab Results– Weight: 2069.17 – 22415.9Weight: 2069.17 – 22415.9– DP Shell: 335149 – 6364756DP Shell: 335149 – 6364756– DP Tube: 17701.66 – 4.26e11DP Tube: 17701.66 – 4.26e11– Q Calc: 107043.7 – 919867.5Q Calc: 107043.7 – 919867.5

• 2401 runs = AAARRRGGGHHH!!!!!2401 runs = AAARRRGGGHHH!!!!!

First Design Pass - MiniTab First Design Pass - MiniTab ResultsResults

Mean o

f q_Calc

25.4

00

22.2

50

19.0

50

15.8

75

12.7

00

9.53

5

6.35

0

600000

500000

400000

300000

2.0

1.8

1.6

1.4

1.2

1.0

0.8

7.0

6.5

6.0

5.5

5.0

4.5

4.0

600000

500000

400000

300000

100908070605040

Tube_OD Shell_ID

Tube_Len N_tube

Main Effects Plot (data means) for q_Calc

Mean o

f DP_Tu

be

25.4

00

22.2

50

19.0

50

15.8

75

12.7

009.

535

6.35

0

1.6000E+11

1.2000E+11

8.0000E+10

4.0000E+10

0

2.0

1.8

1.6

1.4

1.2

1.0

0.8

7.0

6.5

6.0

5.5

5.0

4.5

4.0

1.6000E+11

1.2000E+11

8.0000E+10

4.0000E+10

0

100908070605040

Tube_OD Shell_ID

Tube_Len N_tube

Main Effects Plot (data means) for DP_Tube

Mean o

f DP_Shell

25.4

00

22.2

50

19.0

50

15.8

75

12.7

00

9.53

5

6.35

0

3000000

2000000

1000000

2.0

1.8

1.6

1.4

1.2

1.0

0.8

7.0

6.5

6.0

5.5

5.0

4.5

4.0

3000000

2000000

1000000

100908070605040

Tube_OD Shell_ID

Tube_Len N_tube

Main Effects Plot (data means) for DP_Shell

Mean o

f W

eig

ht_

HE

25.4

00

22.2

50

19.0

50

15.8

75

12.7

00

9.53

5

6.35

0

15000

10000

5000

2.0

1.8

1.6

1.4

1.2

1.0

0.8

7.0

6.5

6.0

5.5

5.0

4.5

4.0

15000

10000

5000

100908070605040

Tube_OD Shell_ID

Tube_Len N_tube

Main Effects Plot (data means) for Weight_HE

First Design PassFirst Design Pass

• FindingsFindings– MiniTab will not do Pareto charts for MiniTab will not do Pareto charts for

systems with more than 2 levels.systems with more than 2 levels.

– Higher levels ( >4) are beneficial for Higher levels ( >4) are beneficial for identifying linear regions and critical identifying linear regions and critical areas.areas.

Second Design PassSecond Design Pass

• Used Excel to find variable Used Excel to find variable combinations with Qcalc/Qdes = 1 combinations with Qcalc/Qdes = 1 +/-10%+/-10%

• 12 combinations met criteria12 combinations met criteria

• Used the max and min in 2Used the max and min in 2ndnd iteration iteration of Matlab (2 level)of Matlab (2 level)

Second Design PassSecond Design Pass

• Matlab VariablesMatlab Variables– 4 variables4 variables

•Tube_ODTube_OD (9.535 – 25.4)e-3 meters(9.535 – 25.4)e-3 meters

•Shell_IDShell_ID (.8 – 1) meters(.8 – 1) meters

•Tube_LenTube_Len (6.5 – 7) meters(6.5 – 7) meters

•N_tubeN_tube (90 – 100)(90 – 100)

– 2 levels2 levels•Gives 2^4 = 16 runsGives 2^4 = 16 runs

Second Design PassSecond Design Pass

• Matlab ResultsMatlab Results– Weight: 3444 – 5773Weight: 3444 – 5773– DP Shell: 122279 – 3933472DP Shell: 122279 – 3933472– DP Tube: 24799 – 41293392DP Tube: 24799 – 41293392– Q Calc: 844667 – 919867Q Calc: 844667 – 919867

• 16 runs = MMM! (Much more 16 runs = MMM! (Much more manageable)manageable)

Second Design Pass - MiniTab Second Design Pass - MiniTab ResultsResults

Term

Standardized Effect

BD

BC

CD

AD

AB

A

B

C

D

9080706050403020100

2.45Factor

N_TUBE

NameA TUBE_OD

B SHELL_IDC TUBE_LEND

Pareto Chart of the Standardized Effects(response is q_Calc, Alpha = .05)

Term

Standardized Effect

AC

C

AD

D

A

8007006005004003002001000

2.2Factor NameA TUBE_OD

C TUBE_LEND N_TUBE

Pareto Chart of the Standardized Effects(response is DP_Tube, Alpha = .05)

Term

Standardized Effect

BC

AC

C

AB

B

A

120010008006004002000

2Factor NameA TUBE_ODB SHELL_IDC TUBE_LEN

Pareto Chart of the Standardized Effects(response is DP_Shell, Alpha = .05)

Term

Standardized Effect

D

BC

A

C

B

7006005004003002001000

2.2Factor

N_TUBE

NameA TUBE_ODB SHELL_IDC TUBE_LEND

Pareto Chart of the Standardized Effects(response is Weight_HE, Alpha = .05)

Second Design Pass - Second Design Pass - OptimizerOptimizer

Second Design Pass - Second Design Pass - OptimizerOptimizer

Second Design PassSecond Design Pass• Check W/ MatlabCheck W/ Matlab

– Number of Tubes N = 100.00 Number of Tubes N = 100.00 – Number of Passes = 2.00 Number of Passes = 2.00 – Tubes OD OD = 0.0191 m Tubes OD OD = 0.0191 m – Tubes ID ID = 0.0135 m Tubes ID ID = 0.0135 m – Tube Length L = 6.7500 m Tube Length L = 6.7500 m – Tube Pitch PT = 0.0238 m Tube Pitch PT = 0.0238 m – Shell ID = 0.9000 mShell ID = 0.9000 m– Baffle Space = 0.1048 m Baffle Space = 0.1048 m – Number of Baffles = 63.0000 m Number of Baffles = 63.0000 m – Desired Heat Transfer Rate = 928501.84 WDesired Heat Transfer Rate = 928501.84 W– Calculated Heat Transfer Rate = 843364.57 WCalculated Heat Transfer Rate = 843364.57 W– Difference = 85137.28 WDifference = 85137.28 W– Desired-to-Calculated Ratio = Desired-to-Calculated Ratio = 1.101.10 – Shell Side Delta-P = Shell Side Delta-P = 1517783.93 Pa1517783.93 Pa – Tube Side Delta-P = Tube Side Delta-P = 138509.45 Pa138509.45 Pa – Total HE Weight = Total HE Weight = 4550.87 kg4550.87 kg

Second Design PassSecond Design Pass

• Fouling FactorFouling Factor– Increased tube number to account for Increased tube number to account for

foulingfouling– 116 tubes required for Q/q=1116 tubes required for Q/q=1– 135 tubes for Q/q=0.91135 tubes for Q/q=0.91

•DP Shell: UnchangedDP Shell: Unchanged

•DP Tube: 79943.83 PaDP Tube: 79943.83 Pa

•Weight: 4607.82 KgWeight: 4607.82 Kg

Other FactorsOther Factors

• Full Factorial desirableFull Factorial desirable– City Water Flow RateCity Water Flow Rate– Baffle SpacingBaffle Spacing– Baffle Cut HeightBaffle Cut Height– Tube PitchTube Pitch– Tube Layout AngleTube Layout Angle

– Yields 12 factors Yields 12 factors • Even 2 levels is long: Even 2 levels is long: 4096 data points4096 data points

Design ResultsDesign Results

• Length: 6.5mLength: 6.5m

• Shell ID: 1mShell ID: 1m

• Tube OD: 19.1mm Tube OD: 19.1mm

• Tube Length: 6.75mTube Length: 6.75m

• Number of Tubes: 135Number of Tubes: 135