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