Tuesday, November 02, 2004

Waffle Fries at Chick-Fil-A

Izzy and I ate at Chick-Fil-A last night on the way to his place to play lots of GTA: San Andreas. I got nuggets with polynesian sauce and waffle fries. Izzy got a sandwich. Oh and we both bought southern-style sweet tea (sweetay!) in the middle of Maryland because "chick-a-fil" is a cool southern chain.

We noticed that waffle fries cool awfully fast, faster than standard fries. Being engineers, we developed a theory to explain this.

The waffle structure of the fry actually raises the surface area to fry volume ratio above that of standard stick fries. The typical heat transfer variable that governs this is the Biot number. We believe that because of the shape of the fry, the characteristic length of a single waffle fry is reduced below that of a typical stick fry found at a milspec burger joint (like the Burger King on base).

I've been thinking about this a little more in the past few minutes and I think that there is another effect that contributes as well. I think the characteristic fry length is smaller for the waffle fry as I said before. I also think that the waffle structure increases convective heat dissipation by changing the air flow pattern and thereby increasing the convective constant. Essentially the waffle fry is a tiny radiator.

Come to think of it Chick-Fil-A probably realizes this as well. I bet they use the waffle fry because it is quicker to cook than a standard stick fry. Unfortunately the physics work both ways and it also cools faster too.

Yeah, yeah, I'm a geek. But Izzy suggested I write this so at least I'm not alone.

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