ME 414- FLUID SYSTEMS DESIGNPROFESSOR: JOHN TOKSOYSPRING 2009TEAM

• Tyler Laughlin• Denis Shkurapet• Ethan Sneed• Matt Tolentino• Tyler Turk

Heat Exchanger Design

Objective

To design a heat exchanger than meets the following criteria:

Cools liquid from 45 C to 25 C Must be less than 7 meters in length Shell diameter is less than 2 meters Minimize weight of the tube and shell Minimize pressure drop Heat transfer ratio of 1

Design Parameters

# of tubes passedTube outer diameterTube inner diameterMaterialBafflesShell thicknessShell MaterialStrength factorsFluid allocationType of flow (parallel or counter)

Analysis

Use Minitab and Matlab

Minitab Use to obtain the main effects plots, Pareto charts, and

the response optimizer.

Matlab Use to run analysis of the DOE files and to give us the

outputs of total weight, calculated heat transfer, cost, and pressure drops.

DOE allows us to determine the most important variables in this design.

Results

Variable Initial value Final Value Explanations

Shell fluid Water Water Given Input

Tube fluid Chemical (water prop) Chemical (water prop) Given Input

M-dot shell 3.45 kg/s 3.9117 kg/sDOE - Optimizer suggested value

Mdot tube 61.11 kg/s 61.11 kg/sGiven value -tube selected for cleaning

T shell in 20°C 20°C Given Input

T tube in 45°C 45°C Given Input

T tube out 25°C 25°C Given Input

Rf tube in .00018 m²K/W .00018 m²K/W Reference value for water

Rf tube shell side .00018 m²K/W .00018 m²K/W Reference value for water

Flow config Parallel ParallelDOE - Optimizer suggested using parallel

# tube pass 1 1The program only allows one pass

# shell pass 1 1 For minimal weight

Results

Baffles No baffles No bafflesTo reduce weight/pressure drop

Shell ID 0.3366 0.3366DOE - Optimizer suggested no change

Shell Th 1.00E-03 1.00E-03DOE - Optimizer suggested no change

Shell Mat'l Stainless Steel 304 Stainless Steel 304Corrosion Resistant/ease of cleaning

Tube Mat'l Stainless Steel 304 Stainless Steel 304Corrosion Resistant/ease of cleaning

Nusselt Shell Dittus Boelter Dittus Boelter Most basic correlation

Nusselt Tube Gnielinski Gnielinski accounts for entrance effects

Pressure Corr Shell Default from textbook Default from textbookOnly option that was applicable

Pressure Corr Tube Default from textbook Default from textbookOnly option that was applicable

Tube OD 6.35e-3 m 6.35E-03DOE - Optimizer suggested no change

Tube Th .711e-3 m 4.57E-04DOE- Optimizer suggested value

Tube Length 2.00 1.85DOE- Optimizer suggested value

Tube Layout Angle 90 90DOE - Optimizer suggested no change

Results

Outputs Initial value Final Value Difference Units

T shell out 353.59°C 318.76°C 34.83 °C

# of tubes 1313 1313 0U (Heat Transfer

Coeff.) 828.48 W/m2.C 876.97 W/m2.C -48.49 W/m2.C

R value 1.00 0.98 0.02

Weight_He 411.21 350.88 kg 60.33 kg

DP Shell 267.89 Pa 335.11 Pa -82.99 Pa

DP Tube 45310.96 Pa 29832.58 Pa 15478.38 Pa

Analysis: 1st DOE

 CounterParallel

700

500

300

4.31252.5875 2.51.5

0.0012500.000533

700

500

300

0.420750.25245 0.00128750.0007500

0.007930.00476

700

500

300

Flow

Mean

M dot Tube Length

Tube th Shewll ID Shell Th

Tube OD

ME 414 Main Effects Plot: Weight_HE

CounterParallel

1000000

500000

0

4.31252.5875 2.51.5

0.0012500.000533

1000000

500000

0

0.420750.25245 0.00128750.0007500

0.007930.00476

1000000

500000

0

Flow

Mean

M dot Tube Length

Tube th Shewll ID Shell Th

Tube OD

ME 414 Main Effects Plot: DP Tube

CounterParallel

1000

500

0

4.31252.5875 2.51.5

0.0012500.000533

1000

500

00.420750.25245 0.00128750.0007500

0.007930.00476

1000

500

0

Flow

Mean

M dot Tube Length

Tube th Shewll ID Shell Th

Tube OD

ME 414 Main Effects Plot: DP Shell

CounterParallel

10000000

7500000

5000000

4.31252.5875 2.51.5

0.0012500.000533

10000000

7500000

5000000

0.420750.25245 0.00128750.0007500

0.007930.00476

10000000

7500000

5000000

Flow

Mean

M dot Tube Length

Tube th Shewll ID Shell Th

Tube OD

ME 414 Main Effects Plot: Q Calc

Analysis: Pareto Charts 1st DOE

ABD

BD

AD

AB

D

AC

B

C

A

16000001400000120000010000008000006000004000002000000

Term

Standardized Effect

2

A FlowB M dotC Tube LengthD Tube th

Factor Name

Pareto Chart of the Standardized Effects(response is Weight, Alpha = 0.05)

AC

BC

C

AB

A

B

200150100500

Term

Standardized Effect

2.0

A FlowB M dotC Tube Length

Factor Name

Pareto Chart of the Standardized Effects(response is DP Shell, Alpha = 0.05)

Flow

Tube Length

14121086420

Term

Standardized Effect

1.98

Pareto Chart of the Standardized Effects(response is DP Tube, Alpha = 0.05)

BC

B

C

6050403020100

Term

Standardized Effect

1.98

B M dotC Tube Length

Factor Name

Pareto Chart of the Standardized Effects(response is Q Calc, Alpha = 0.05)

Analysis: 1st Optimization

Minitab solved for a local solution.

The starting values were changed multiple times until Minitab found a new, more optimal solution.

Analysis: 2nd DOE

CounterParallel

10000000

7500000

5000000

4.31252.5875 2.51.5

0.00057130.0003430

10000000

7500000

5000000

0.420750.25245 0.00128750.0007500

0.007930.00476

10000000

7500000

5000000

Flow

Mean

Mdot Tube Length

Tube Thick Shell ID Shell Thick

Tube OD

ME 414 Main Effects Plot Optimization 2: Q Calc

CounterParallel

150000

100000

50000

4.31252.5875 2.51.5

0.00057130.0003430

150000

100000

50000

0.420750.25245 0.00128750.0007500

0.007930.00476

150000

100000

50000

Flow

Mean

Mdot Tube Length

Tube Thick Shell ID Shell Thick

Tube OD

ME 414 Main Effects Plot Optimization 2: DP Tube

CounterParallel

1000

500

04.31252.5875 2.51.5

0.00057130.0003430

1000

500

00.420750.25245 0.00128750.0007500

0.007930.00476

1000

500

0

Flow

Mean

Mdot Tube Length

Tube Thick Shell ID Shell Thick

Tube OD

ME 414 Main Effects Plot Optimization 2: DP Shell

CounterParallel

700

500

300

4.31252.5875 2.51.5

0.0012500.000533

700

500

300

0.420750.25245 0.00128750.0007500

0.007930.00476

700

500

300

Flow

Mean

M dot Tube Length

Tube th Shewll ID Shell Th

Tube OD

ME 414 Main Effects Plot: Weight_HE

Analysis: 2nd Optimization

Starting values of the optimization were varied with no improvement in performance.

Conclusions: Damn near perfect!

Heat Transfer Coeff : 876.97 W/m2.C

R-value: 0.98Number of tubes: 1313Shell Pressure Loss: 335.11 PaTube Pressure Loss: 29832.58 PaWeight of Heat Exchanger: 350.88

kg

Conclusions: Recommendations

Could be further optimized if Tube Thickness was decreased

Resulting in: Lower weight - decrease of 51.93 kg Lower Tube pressure loss - decrease of 6703.1 Pa No significant loss of R-value

A smaller tube is not commercially availablePossibly achieve greater performance at a

greater price

Questions