we all scream for ice cream
Post on 04-Jan-2016
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Todd Nelson
Kendall Thacker
ME 340 Semester Project
Winter 2014
How long will it take for the outside surface of an ice cream cone to arrive at melting temperature* while walking around?
*Melting occurs at -5.6°C
1) Find properties of air and ice cream at appropriate temperatures
2) Calculate forced convection coefficient (with Whitaker model)
3) Use approx transient response model to find the time required to heat outer surface to melting temperature
4) Perform experiment to validate
**Note: All calculations done using MATLab
Inside AirT=21.3°C
Walking SpeedV=.9 m/s
Ice Cream Properties*K=0.9 w/m°CMelts at T=-5.6°CInitial Temp= -6°CSpecific Heat (Cp)=2.75 KJ/kgK
0.1016 meters
**Thermophysical properties for ice cream , 2006 ASHRAI Handbook for Refrigeration
http://pcfarina.eng.unipr.it/Public/Termofluidodinamica/Utility/Tabelle%20Alimenti.pdf
Time to melt= 7.15 minutes Convection coefficient= 756 W/mk (**Fourier number is 0.07 and the model requires 0.1 or greater
to be accurate. Use with caution)
Assumptions: No radiation effects (eating indoors)
Ice cream geometry is approximated as a sphere
Walking is at constant rate
Previously melted ice cream running down the sides does not effect the heat transfer rate
Ice cream is not being eaten during test
Properties of ice cream are accurate
Time to melt=15 minutes (time to outside surface is completely melted)
Discussion The error between the analytical
and experiment results could be due to over simplified problem setup. For more accurate results, the effect of the melted ice cream on the un-melted portion needs to be accounted for.
Experiment was performed by purchasing chocolate ice cream cone from Cougar Eat and walking around at a steady rate.
Thermophysical properties for ice cream , 2006 ASHRAI Handbook for Refrigeration
http://pcfarina.eng.unipr.it/Public/Termofluidodinamica/Utility/Tabelle%20Alimenti.pdf
Infrared temp sensor to measure surface temperature of ice cream
Thermocouple to measure ambient air temperature
Matlab 2014
Fundamentals of Heat and Mass Transfer 7th edition, Bergman, Lavine, Incropera, Dewitt
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