Heat Exchanger Design

Heat Exchanger Design Optimization with Matlab and Minitab

CUMMINS CONFIDENTIAL

Heat Exchanger Design Goals REQUIRED: 

Must cool the chemical from 45°C to 25°C



Cool with city water at 20°C



Heat exchanger length can not exceed 7 meters



Heat exchanger shell diameter can not exceed 2 meters

This is a Header


2

H.E. Design Goals OPTIMIZATION: 

Minimize Heat Exchanger Weight



Minimize Pressure Drop in Shell



Minimize Pressure Drop in Tubes



Minimize Cost


Parameter Reduction Start

Set Variables

• Original Inputs

32 Inputs

• Design Choices

18

Testing

• One Factor at a Time(OFAT) Runs

4-5

Statistical Analysis

• Minitab Optimization

3-4

All Parameters

1st “Hit List”

Screened List

Found Critical Parameters

Optimized Heat Exchanger dimensions CUMMINS CONFIDENTIAL

First Design Choices Cooling Water From City System 

50psi to 100psi at Shell Inlet (345KPa-690KPa)



Max Shell Pressure Drop Assumed to Be 344KPa to Eliminate Need of Pump.



Shell Thickness

.0125m



Max Tube Velocity

2 m/s to resist erosion CUMMINS CONFIDENTIAL

OFAT Runs One Factor at a Time Runs Allowed the Group to Select the Following Parameters. 

Material

Aluminum 2024-T6



# Passes

1-1



Baffles

No



Pitch, Angle

Triangular, 60 degree



Flow

Counter



Tube Thickness

20 BWG


Design of Experiments The Group Ran the DOE in Matlab to Obtain Multiple Runs While Varying the Following Parameters.  Mdot Shell  Shell Diameter • 20% higher and lower values

 Tube Length  Tube Outer Diameter



Var_Tube_Len

= [3.6



Var_Shell_ID

= [0.3366



Var_Tube_OD

= [6.25E-3

5.4]; .4382]; 9.525E-3];


Minitab Optimization 

A Factorial Design Was Created With the Following Information.



Main Effects Plots

Main Effects Plot for DP Tube

Main Effects Plot for DP Shell

Data Means

Tube Length

80000

Data Means

Tube Length

Shell ID

60000

350000

40000

300000 250000

20000

200000

0 3.6

5.4 Tube OD

80000

0.3366

0.4382

Mean

Mean

Shell ID

400000

3.6

5.4 Tube OD

400000

60000

350000 300000

40000

250000

20000

200000

0 0.006250

0.009525

0.006250


0.009525

0.3366

0.4382


Pareto Charts

Pareto Chart of the Effects

Pareto Chart of the Standardized Effects

(response is DP Tube, Alpha = 0.05)

(response is DP Shell, Alpha = 0.05)

F actor A B C

C

3.18

N ame Tube Length S hell ID Tube O D

F actor A B C

B

A

Term

Term

C

AC

A

B

AC

0

10000

20000

30000 40000 Effect

50000

60000

70000

0

10


20

30 40 50 Standardized Effect

60

70

N ame Tube Length S hell ID Tube O D


Response Optimizer



The Minitab Optimization Chart


References 

Wolverine Tube, Initials. (2009). Wolverine tube heat transfer data book [1.6.#]. (Fouling Factors and Erosion Speeds), Retrieved from http://www.wlv.com/products/databook/ch1_6.pdf
