finite element analysis of heat transfer in single and double walled beverage containers by peter tu...
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© Copyright 2014 by Peter Tu 1
Finite Element Analysis of Heat Transfer in Single and Double Walled
Beverage Containers
byPeter Tu
An Engineering Project Submitted to the GraduateFaculty of Rensselaer Polytechnic Institute
in Partial Fulfillment of theRequirements for the degree of
MASTER OF ENGINEERINGMajor Subject: Mechanical Engineering
12/9/2014
© Copyright 2014 by Peter Tu 2
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
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© Copyright 2014 by Peter Tu 3
Theory
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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 wall4. Lost to the environment via convection
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Methodology
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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
© Copyright 2014 by Peter Tu 612/9/2014
• 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
Analysis Models
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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
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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
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Measured Data vs. Thermal Model
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0200
400600
8001000
12001400
16001800
2000300.00
310.00
320.00
330.00
340.00
350.00
360.00
370.00
380.00
Water Temperature vs. TimeWater Temperature
Time (s)
Tem
pera
ture
(K)
• 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
© Copyright 2014 by Peter Tu 10
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
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