Heat Exchanger DesignThermal / Fluid System Design

Final ProjectDepartment of Mechanical Engineering

Fall 2005

December 13, 2005

Team Members:Andrew Burian

Jack CopenhaverChris HaireBrandin Ray

Professor: John Toksoy

Heat Exchanger DesignThermal / Fluid System Design

Final ProjectDepartment of Mechanical Engineering

Fall 2005

December 13, 2005

Team Members:Andrew Burian

Jack CopenhaverChris HaireBrandin Ray

Professor: John Toksoy

Required Design ParametersRequired Design Parameters Heat Exchanger Must Cool the Chemical From

35°C to 25°C Cannot Exceed 7m In Length or 2m in Diameter Minimize Heat Exchanger Shell Diameter and

Tube Length to Reduce Cost Minimize Pressure Drop Chemical Mass Flow Rate Fixed at 80 kg/hr City Water to be Used as Cooling Fluid With an

Inlet Temperature of 20°C

Heat Exchanger Must Cool the Chemical From 35°C to 25°C

Cannot Exceed 7m In Length or 2m in Diameter Minimize Heat Exchanger Shell Diameter and

Tube Length to Reduce Cost Minimize Pressure Drop Chemical Mass Flow Rate Fixed at 80 kg/hr City Water to be Used as Cooling Fluid With an

Inlet Temperature of 20°C

AssumptionsAssumptions

Isothermal Material Properties (Shell and Tube)

Constant Properties Steady State Incompressible Fluids 24 Hour Duty Cycle Heat Transfer Through Shell is Minimal

Isothermal Material Properties (Shell and Tube)

Constant Properties Steady State Incompressible Fluids 24 Hour Duty Cycle Heat Transfer Through Shell is Minimal

Initial Possible Factors Effecting Heat Exchanger Design

Initial Possible Factors Effecting Heat Exchanger Design

Mass Flow Rate (Shell Side)

Tube Length Shell I.D. Tube Pitch Tube Material Shell Thickness

Mass Flow Rate (Shell Side)

Tube Length Shell I.D. Tube Pitch Tube Material Shell Thickness

Tube O.D. Tube Thickness Number of Tubes Baffle Spacing Baffle Cut Shell Material Flow Direction

Tube O.D. Tube Thickness Number of Tubes Baffle Spacing Baffle Cut Shell Material Flow Direction

“One Factor at a Time” Study“One Factor at a Time” Study

Factors Found to Have Greatest Effect on Weight and Heat TransferFactors Found to Have Greatest

Effect on Weight and Heat Transfer Tube Length Shell I.D. Baffles Tube O.D.

Tube Length Shell I.D. Baffles Tube O.D.

Number of Tubes Pitch (Square or

Triangular) Mass Flow Rate

Number of Tubes Pitch (Square or

Triangular) Mass Flow Rate

Main Effects Plots With Seven Factors

Main Effects Plots With Seven Factors

Mean o

f W

eig

ht 0.0109530.008096

600

500

400

0.3510.259 4.63.4

213

600

500

400

10 10

2.31.7

600

500

400

tube od shell id tube length

tube material tube sq pitch baffle

baffle space

Main Effects Plot (data means) for Weight

Mean o

f (D

esi

red -

Calc

ula

ted)

0.0109530.008096

100000

-100000

-3000000.3510.259 4.63.4

213

100000

-100000

-30000010 10

2.31.7

100000

-100000

-300000

tube od shell id tube length

tube material tube sq pitch baffle

baffle space

Main Effects Plot (data means) for (Desired - Calculated)

Final Factors Final Factors

Tube Length Tube Material Tube O.D. Shell I.D.

Tube Length Tube Material Tube O.D. Shell I.D.

Main Effects Plots With Final Factors

Main Effects Plots With Final Factors

Mean o

f q C

alc

0.0109530.008096

1200000

1100000

1000000

900000

800000

0.3510.259

4.63.4

1200000

1100000

1000000

900000

800000

213

tube od shell id

tube length tube material

Main Effects Plot (data means) for q Calc

Mean o

f D

P T

ube

0.0109530.008096

10000

8000

6000

4000

0.3510.259

4.63.4

10000

8000

6000

4000

213

tube od shell id

tube length tube material

Main Effects Plot (data means) for DP Tube

Mean o

f D

P S

hell

0.0109530.008096

2000

1500

10000.3510.259

4.63.4

2000

1500

1000213

tube od shell id

tube length tube material

Main Effects Plot (data means) for DP Shell

Final Design Specifications(Clean Heat Exchanger)

Final Design Specifications(Clean Heat Exchanger)

Shell I.D. =.3048m Shell Thick. = 2mm Tube O.D. = 9.25mm Tube Thick. = .559mm Number of Tubes = 550 Weight = 590.80kg

Shell I.D. =.3048m Shell Thick. = 2mm Tube O.D. = 9.25mm Tube Thick. = .559mm Number of Tubes = 550 Weight = 590.80kg

Initial vs. Final SpecificationsInitial vs. Final SpecificationsInitial Final

Mass Flow Rate ……….. 59.0 kg/s 43.0 kg/s

Flow Direction …………. Counter Flow Counter Flow

Shell I.D. ……………….. 0.3784 m 0.3048 m

Shell Thickness ……….. 2.0 mm 2.0 mm

Shell Material ………….. Bronze Stainless Steel

Tube O.D. ……………… 9.525 mm 9.525 mm

Tube Thickness ……….. 0.889 mm 0.559 mm

Tube Length …………… 3.2 m 4 m

Number of Tubes……… 889 550

Tube Material…………... Aluminum Stainless Steel

Tube Pitch………………. Triangle (30°) Triangle (60°)

Baffle space…………….. 0.75 m 2 m

Baffle Cut……………….. 0.116 m 0.150 m

Initial Final

Mass Flow Rate ……….. 59.0 kg/s 43.0 kg/s

Flow Direction …………. Counter Flow Counter Flow

Shell I.D. ……………….. 0.3784 m 0.3048 m

Shell Thickness ……….. 2.0 mm 2.0 mm

Shell Material ………….. Bronze Stainless Steel

Tube O.D. ……………… 9.525 mm 9.525 mm

Tube Thickness ……….. 0.889 mm 0.559 mm

Tube Length …………… 3.2 m 4 m

Number of Tubes……… 889 550

Tube Material…………... Aluminum Stainless Steel

Tube Pitch………………. Triangle (30°) Triangle (60°)

Baffle space…………….. 0.75 m 2 m

Baffle Cut……………….. 0.116 m 0.150 m

The Argument for Stainless Steel

The Argument for Stainless Steel

Stainless SteelPros ConsStainless SteelPros Cons Not Chemically

Reactive Easy to Clean Not as Easily

Damaged During Cleaning

Food Industry Uses Easy to Repair

Not Chemically Reactive

Easy to Clean Not as Easily

Damaged During Cleaning

Food Industry Uses Easy to Repair

Harder to Machine Shipping

Costs/Requirements Small Decrease in

Heat Transfer

Harder to Machine Shipping

Costs/Requirements Small Decrease in

Heat Transfer

AluminumPros ConsAluminumPros Cons Easy to Work With Light Weight Slightly Increased

Heat Transfer

Easy to Work With Light Weight Slightly Increased

Heat Transfer

Soft – Easier to Damage During Maintenance

Hard to Repair Anodic to Most Other

Metals Chemically Reactive Weak (With Respect

to Stainless)

Soft – Easier to Damage During Maintenance

Hard to Repair Anodic to Most Other

Metals Chemically Reactive Weak (With Respect

to Stainless)

Stress AnalysisStress Analysis

Using General Material Properties for Annealed 300 Series Stainless Steel and “Worse Case” Heat Exchanger Pressures Taken From D.O.E. Study

Using General Material Properties for Annealed 300 Series Stainless Steel and “Worse Case” Heat Exchanger Pressures Taken From D.O.E. Study

H. E. Specifications and PropertiesH. E. Specifications and Properties

Shell I.D. = 0.3048 m Shell Thick. = 2 mm Tube O.D. = 9.25 mm Tube Thick. = 0.559 mm

Shell I.D. = 0.3048 m Shell Thick. = 2 mm Tube O.D. = 9.25 mm Tube Thick. = 0.559 mm

∆ PShell = 3000 Pa

∆PTube = 14000 Pa E = 190 GPa α = 17.2 e – 6 σY = 6.55 GPa

∆ PShell = 3000 Pa

∆PTube = 14000 Pa E = 190 GPa α = 17.2 e – 6 σY = 6.55 GPa

Calculated Stresses σY = 6.55 GPa

Calculated Stresses σY = 6.55 GPa

Shell Hoop Stress = 2.29 GPa Shell Long. Stress = 1.14 GPa

Tube Hoop Stress = 1.02 GPa Tube Thermal Stress = 19.7 KPa

Shell Hoop Stress = 2.29 GPa Shell Long. Stress = 1.14 GPa

Tube Hoop Stress = 1.02 GPa Tube Thermal Stress = 19.7 KPa

Questions?Questions?

AppendixAppendix

MATLAB Results With Optimized Factors

MATLAB Results With Optimized Factors

Desired Heat Transfer Rate = 928500.92 W Calculated Heat Transfer Rate = 929320.42

W Difference = -819.50 W Desired-to-Calculated Ratio = 1.00

HE Pressure Drop ===================== Shell Side Delta-P = 2181.04 Pa Tube Side Delta-P = 5363.92 Pa

Heat Exchanger Weight ===================== Shell Weight = 60.72 kg Tube Weight = 273.66 kg Shell Fluid Weight = 134.82 kg Tube Fluid Weight = 121.61 kg ----------- Total HE Weight = 590.80 kg

Desired Heat Transfer Rate = 928500.92 W Calculated Heat Transfer Rate = 929320.42

W Difference = -819.50 W Desired-to-Calculated Ratio = 1.00

HE Pressure Drop ===================== Shell Side Delta-P = 2181.04 Pa Tube Side Delta-P = 5363.92 Pa

Heat Exchanger Weight ===================== Shell Weight = 60.72 kg Tube Weight = 273.66 kg Shell Fluid Weight = 134.82 kg Tube Fluid Weight = 121.61 kg ----------- Total HE Weight = 590.80 kg

Tube Side Heat Transfer Parameters=====================================

=== Number of Tubes N = 550.00 Number of Passes = 1.00 Tubes OD OD = 0.0095 m Tubes ID ID = 0.0084 m Tube Length L = 4.0000 m Tube Flow Area Af = 0.0305 m2 Tube Solid Area As = 0.0392 m2 Tube Pitch PT = 0.0119 m Average Velocity V = 0.73 m/s Mass Velocity G = 727.87 kg/m2.s Reynolds Number Re = 7657.84

TURBULENT Nusselt Number Nu = 63.05 HT Coefficient h = 4629.32 W/m2.C

Tube Side Heat Transfer Parameters=====================================

=== Number of Tubes N = 550.00 Number of Passes = 1.00 Tubes OD OD = 0.0095 m Tubes ID ID = 0.0084 m Tube Length L = 4.0000 m Tube Flow Area Af = 0.0305 m2 Tube Solid Area As = 0.0392 m2 Tube Pitch PT = 0.0119 m Average Velocity V = 0.73 m/s Mass Velocity G = 727.87 kg/m2.s Reynolds Number Re = 7657.84

TURBULENT Nusselt Number Nu = 63.05 HT Coefficient h = 4629.32 W/m2.C

Overall Heat Transfer Coefficient =============================

========= U (Tube Outside Area) = 1975.17

W/m2.C Heat Transfer Rate =============================

========= Desired Heat Transfer Rate =

928500.92 W Calculated Heat Transfer Rate =

929320.42 W Difference = -819.50 W Desired-to-Calculated Ratio =

1.00

Overall Heat Transfer Coefficient =============================

========= U (Tube Outside Area) = 1975.17

W/m2.C Heat Transfer Rate =============================

========= Desired Heat Transfer Rate =

928500.92 W Calculated Heat Transfer Rate =

929320.42 W Difference = -819.50 W Desired-to-Calculated Ratio =

1.00

Shell Side Heat Transfer Parameters =============================

========= Shell ID = 0.3048 m Shell Cross Sec Area = 0.0730 m2 Shell Flow Area = 0.1219 m2 Baffle Space = 2.0000 m Number of Baffles = 1.0000 m Shell Equivalent Dia = 0.0069 m Mass Velocity G = 352.69

kg/m2.s Reynolds Number Re = 2576.25

TURBULENT Nusselt Number Nu = 51.07 HT Coefficient h = 4502.58

W/m2.C

Shell Side Heat Transfer Parameters =============================

========= Shell ID = 0.3048 m Shell Cross Sec Area = 0.0730 m2 Shell Flow Area = 0.1219 m2 Baffle Space = 2.0000 m Number of Baffles = 1.0000 m Shell Equivalent Dia = 0.0069 m Mass Velocity G = 352.69

kg/m2.s Reynolds Number Re = 2576.25

TURBULENT Nusselt Number Nu = 51.07 HT Coefficient h = 4502.58

W/m2.C

Additional Plots From Seven Factors MINITAB Run

Additional Plots From Seven Factors MINITAB Run

Mean o

f DP S

hell 0.0109530.008096

2000

1500

10000.3510.259 4.63.4

213

2000

1500

100010 10

2.31.7

2000

1500

1000

tube od shell id tube length

tube material tube sq pitch baffle

baffle space

Main Effects Plot (data means) for DP Shell

Mean o

f q C

alc

0.0109530.008096

1200000

1000000

800000

0.3510.259 4.63.4

213

1200000

1000000

800000

10 10

2.31.7

1200000

1000000

800000

tube od shell id tube length

tube material tube sq pitch baffle

baffle space

Main Effects Plot (data means) for q Calc

Pareto Charts With All Combinations Considered

Pareto Charts With All Combinations Considered

Term

Standardized Effect

BCD

ABD

BD

ACD

ABC

CD

AD

BC

AB

AC

D

B

C

A

1000080006000400020000

13Factor

tube material

NameA tube odB shell id

C tube lengthD

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

Term

Standardized Effect

ABC

ACD

AC

ABD

BCD

AB

AD

CD

BC

A

BD

C

D

B

250200150100500

12.7Factor

tube material

NameA tube odB shell idC tube lengthD

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

Term

Effect

BCD

ABD

CD

BD

AD

D

ACD

ABC

AB

BC

AC

B

A

C

120010008006004002000

Factor

tube material

NameA tube odB shell idC tube lengthD

Pareto Chart of the Effects(response is DP Shell, Alpha = .05)

Term

Effect

CD

AD

ACD

ABD

D

BCD

BD

ABC

AC

BC

AB

C

A

B

70006000500040003000200010000

Factor

tube material

NameA tube odB shell idC tube lengthD

Pareto Chart of the Effects(response is DP Tube, Alpha = .05)

Pareto Charts With Irrelevant Combinations Removed

Pareto Charts With Irrelevant Combinations Removed

Term

Standardized Effect

BC

AB

AC

D

B

C

A

50403020100

2.31Factor

tube material

NameA tube odB shell id

C tube lengthD

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

Term

Standardized Effect

AD

CD

BC

A

BD

C

D

B

403020100

2.36Factor

tube material

NameA tube odB shell idC tube lengthD

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

Term

Effect

ABC

AB

BC

AC

B

A

C

120010008006004002000

Factor NameA tube odB shell idC tube length

Pareto Chart of the Effects(response is DP Shell, Alpha = .05)

Term

Effect

ABC

AC

BC

AB

C

A

B

70006000500040003000200010000

Factor NameA tube odB shell idC tube length

Pareto Chart of the Effects(response is DP Tube, Alpha = .05)

CreditsCredits

Minitab 14 MatLab 7.0

Minitab 14 MatLab 7.0