hungry??? grab a chimichanga !

Steve McFarlandAaron Boyd

As I move on to the 5th hour of heat transfer homework, my hunger suddenly takes over and I cannot concentrate anymore. I need a chimichanga! I buy one from the vending machine and pop it in the oven. As I watch it cook, my engineering mind takes over, and I can’t help but wonder, “how hot is the chimichanga at a given time?”

Using the Lumped Capacitance Method, assuming the chimichanga to behave like a cylindar, and using thermophysical properties of water, we determined the temperature of a chimichanga at different times, cooking at 350 degrees F.

T(t) = T ∞ + (To - T ∞)e^(-h As t)/(ρ cp V)

Bi = (h Lc)/k

For full results, see appendix

Temperature of Chimichanga goes up quickly and levels off around 350 degrees after approximately 1 hour...but you probably don’t want to eat it!

The biot number is too high to validly use the lumped capacitance method, but it gives a good estimate of the temperature at any given time.

See attached file