Transcript Final Presentation.pptx

Finite Element Analysis of Heat
Transfer in Single and Double Walled
Beverage Containers
by
Peter Tu
An Engineering Project Submitted to the Graduate
Faculty of Rensselaer Polytechnic Institute
in Partial Fulfillment of the
Requirements for the degree of
MASTER OF ENGINEERING
Major Subject: Mechanical Engineering
12/9/2014
© Copyright 2014 by Peter Tu
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Problem Description
• Generate models of single wall and double
wall glass cups
• Perform heat transfer analysis of models
• Gather measurement data to verify model
behavior
• Update the double wall glass cup thermal
model inputs and compare to the measured
data
12/9/2014
© Copyright 2014 by Peter Tu
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Theory
1. The inner wall obtains thermal energy and transfers the energy to towards the second
wall via thermal conduction
2. The gas in between the two walls then transfer the thermal energy to the second wall
through convection
3. The energy is then conducted through the second wall
4. Lost to the environment via convection
12/9/2014
© Copyright 2014 by Peter Tu
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Methodology
12/9/2014
© Copyright 2014 by Peter Tu
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Double Wall Glass Cup
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Kiran Tea Glass distributed exclusive by Teavana
NX 6.0 used to generate CAD model, 2D sketches
The cup, air, and water were modeled as separate sketches
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© Copyright 2014 by Peter Tu
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Analysis Models
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The cup, air, and water sketches import into COMSOL
The same geometry used for both the single and double walled glass cups
2D Axisymmetric, Transient, Conductive Heat Transfer in Solids Model
COMSOL built in material properties used to solve equations
Initial values and boundary conditions applied
Mesh convergence study performed
30 minute study, maximum step size controlled to 60 seconds
12/9/2014
© Copyright 2014 by Peter Tu
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Single Wall Cup
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Spike of thermal heat transfer at beginning of study
Points C and D are relatively close in temperature throughout the study duration
Top surface of the water loses heat the fastest
12/9/2014
© Copyright 2014 by Peter Tu
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Double Walled Cup
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Similar spike of thermal heat transfer at beginning of study as with single wall cup
Points C and D are significantly different in temperature throughout the study duration
Water overall loses heat slower than the single wall cup
12/9/2014
© Copyright 2014 by Peter Tu
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Measured Data vs. Thermal Model
Water Temperature vs. Time
380.00
Water Temperature
370.00
Temperature (K)
360.00
350.00
340.00
330.00
320.00
310.00
300.00
0
500
1000
1500
2000
Time (s)
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Water temperature loss behavior is replicated by the measured data
Overall temperature loss is different:
• The convection coefficients used in the thermal model could be lower than reality
• Significantly more heat loss through the cup bottom and the thermometer
12/9/2014
© Copyright 2014 by Peter Tu
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Conclusions
• Double walled cups are demonstrated to be
more effective at keeping hot liquids hot for
longer periods of time than single walled cups
• The transfer of heat energy through double
walled cups is significantly slowed down by
the air gap
• Refinement of the thermal models is needed
to mimic the measured data
12/9/2014
© Copyright 2014 by Peter Tu
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