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Purdue School of Engineering andTechnology

Heat Exchanger Design ProjectDepartment of Mechanical Engineering

ME 414 Thermal / Fluid System DesignFinal Project

December 13, 2005

Group Members:

David Langenderfer

Rishi Govalakrishnan

Dan Langenderfer Vincent Liaw

Profess

or: Mr. John Toksoy

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Problem Statement

Design a heat exchanger flowing achemical at 80,000 kg/hr to drop the fluidtemperature from 35°C to 25°C

Cooling chemical is city water flowing at20°C

The shell may not exceed 2 meters in

diameter and 7 meters in length Weight, pressure drop, and cost should be

minimized

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Assumptions

Process and cooling fluid have minimalcorrosive properties

Properties of fluid are similar to water

Counter flow to improve effectiveness

Tube pitch set at 90 degrees

Pitch ratio of 1.25 (rule of thumb) Shell side mass velocity set to 140,000

kg/hr

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Matlab Implementation

Initially used to determine possibledimensions of an acceptable heatexchanger

Output from Matlab was inputted intoMinitab for optimization

Compared results from Matlab output andMinitab optimization

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Funneling Effect

Tube OD, Shell ID, Length,Number of Passes, TubeMaterial, Baffles, Baffle

Spacing

Tube OD, Shell ID,Length

7 Factors

3 Factors

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Optimization

Obtained results with 7 parameters fromMatlab

Using DOE Factorial Response in Minitabwe reduced the parameters by utilizingMain Effects plots

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Determining Effects on Heat

Exchanger

Key variables for an effective heat exchanger

Tube OD

Shell ID

Tube Length

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Decisions from Main Effects

Two pass on tube side:

Minimal foot print on shop floor

Minimize leak points

Increases pressure drop

Allows for independent expansion of tubes

and shell1

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Decisions Cont’d

Counter flow is desirable for a two tubepass exchanger to increase effectivetemperature difference1

Aluminum minimized weight with no effecton heat transfer

No baffles due to large increase inpressure drop on shell side

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Optimization Plots

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Results

Tube OD: 0.0095 m

Shell ID: 0.3874 m

Length: 3.0 m Tube velocity: 1.54 m/s (Range 0.9 - 2.4 m/s)

Turbulent flow promoting high heat

exchange on shell and tube Heat transfer is 6% over desired heat

transfer to accommodate for future fouling

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Results (cont’d)

Δ P Shell: 2,513 Pa ( 0.365 PSI)

Δ P Tube: 38,450 Pa (5.577 PSI)

Weight: 496 kg (1094 lbs) Number of Tubes: 750

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Lessons Learned

Optimization using interaction betweenMinitab and Matlab

How to work as a team

Lots of decisions to make when given anopen ended question

Many solutions to a simple problem Finish projects early (12/4/2005)

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References

1. Heat Exchangers Selection, Rating, and Thermal Design Kakaç and LiuCRC Press, 2nd Edition, 2002

2. ME 414 Lecture NotesProfessor John Toksoy, 2005

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Questions

Documents

f05_team2