Download
we all scream for ice cream n.
Skip this Video
Loading SlideShow in 5 Seconds..
We all scream for ice cream PowerPoint Presentation
Download Presentation
We all scream for ice cream

We all scream for ice cream

144 Vues Download Presentation
Télécharger la présentation

We all scream for ice cream

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. We all scream for ice cream Todd Nelson Kendall Thacker ME 340 Semester Project Winter 2014

  2. Problem Statement • 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

  3. Procedure • Find properties of air and ice cream at appropriate temperatures • Calculate forced convection coefficient (with Whitaker model) • Use approx transient response model to find the time required to heat outer surface to melting temperature • Perform experiment to validate **Note: All calculations done using MATLab

  4. Problem Parameters 0.1016 meters Walking Speed V=.9 m/s Ice Cream Properties* K=0.9 w/m°C Melts at T=-5.6°C Initial Temp= -6°C Specific Heat (Cp)=2.75 KJ/kgK Inside Air T=21.3°C • **Thermophysical properties for ice cream , 2006 ASHRAI Handbook for Refrigeration http://pcfarina.eng.unipr.it/Public/Termofluidodinamica/Utility/Tabelle%20Alimenti.pdf

  5. Analytical Results • 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

  6. Experimental Results & Discussion Experiment was performed by purchasing chocolate ice cream cone from Cougar Eat and walking around at a steady rate. • 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.

  7. References • Fundamentals of Heat and Mass Transfer 7th edition, Bergman, Lavine, Incropera, Dewitt • Thermophysical properties for ice cream , 2006 ASHRAI Handbook for Refrigeration http://pcfarina.eng.unipr.it/Public/Termofluidodinamica/Utility/Tabelle%20Alimenti.pdf Equipment Used • Infrared temp sensor to measure surface temperature of ice cream • Thermocouple to measure ambient air temperature • Matlab 2014