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

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

Theory The inner wall obtains thermal energy and transfers the energy to towards the second wall via thermal conduction The gas in between the two walls then transfer the thermal energy to the second wall through convection The energy is then conducted through the second wall Lost to the environment via convection 12/9/2014 © Copyright 2014 by Peter Tu

Methodology 12/9/2014 © Copyright 2014 by Peter Tu

Double Wall Glass Cup 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 12/9/2014 © Copyright 2014 by Peter Tu

Analysis Models 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

Single Wall Cup 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

Double Walled Cup 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

Measured Data vs. Thermal Model 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

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