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You ’ re Ready, but is your pizza Hot?

You ’ re Ready, but is your pizza Hot?. By Kasey Gillespie and Leonidas Leite. Project Goals. Model the rate pizza cools down at room temperature Determine if a box lined with a tin foil keeps the pizza warm longer Suggest methods for improving pizza boxes. Experimental design.

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You ’ re Ready, but is your pizza Hot?

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  1. You’re Ready, but is your pizza Hot? By Kasey Gillespie and Leonidas Leite

  2. Project Goals • Model the rate pizza cools down at room temperature • Determine if a box lined with a tin foil keeps the pizza warm longer • Suggest methods for improving pizza boxes

  3. Experimental design • Heat oven to approximate temperature of Little Caesars’ warming oven (71 degrees C) • Place pizza in oven and allow its temperature to stabilize. • Remove pizza to wooden table at room temperature, insert thermocouple and record data • Two pizzas were used: first pizza in standard box, second pizza lined with foil in box First Experiment Pizza box Pizza Second Experiment Thin foil 35.6 C TC

  4. Experimental results The pizza with foil took 10 minutes longer to cool to 39 C

  5. Modeling the experiment with no foil • FIRST MODEL – Free convection inside of the box • Assumptions • The whole pizza is a lump—using one set of thermophysical properties is acceptable • The box surface temperature is the average temperature of the pizza and the surroundings • The thermophysical properties of the pizza could be measured at the average temperature during the time period • The pizza is a finite flat plate • The analytical method works because Fo >= 0.2 • T(x,t) = Tinf +(Ti-Tinf)C1cos(ζ1x/L)exp(-ζ12αt/L2)

  6. Comparison of first model to experimental data

  7. Modeling the experiment with no foil • SECOND MODEL – Free convection outside of the box • Assumptions • The whole pizza and box together is a single lump—using one set of thermophysical properties is acceptable • The thermophysical properties of the pizza could be measured at the average temperature during the time period • The pizza is a finite flat plate • The analytical method works because Fo >= 0.2 • T(x,t) = Tinf +(Ti-Tinf)C1cos(ζ1x/L)exp(-ζ12αt/L2)

  8. Comparison of Second model to experimental data

  9. What did the foil do? • The foil did not reduce heat transfer due to radiation it actually served as an inhibitor of convective heat transfer Less convective heat loss Tin foil Insulating Air

  10. Recommendations • Since the foil only acted as an insulation to convection it would be better to use a material that had a lower coefficient of thermal conductivity (K) • Cardboard—the same material as used on the box • Wax paper • Parchment paper • Whatever insulation is used, it should sit directly on top of the pizza instead of lining the actual box • Little Caesars could offer the extra thermal insulation for an extra 5 cent charge • Eat the pizza before it cools down, it tastes better

  11. Conclusion • The second analytical method provided a good model for the experimental data of the non-foil pizza • The pizza covered in foil could only be modeled with more complex analytical methods that are beyond the scope of this course • Heat loss of the pizza can be decreased by placing a low-cost insulating material on top of the pizza, which would increase customer satisfaction

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