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Boiling pan determinants

Posted by aliris19 (My Page) on
Tue, Apr 3, 12 at 11:52

Well it's egg-boiling time of the year, which seemingly provides a rather fine practical opportunity for observing a range's and the pots used thereon, boiling properties.

In a not-very-controlled experiment I brought one layer of fridge-cold eggs:
~ covered with warm water in a:
(i) 7.5" enameled iron straight-sided pot,
(ii) 8.5" aluminum straight-sided pot
~covered with cold tap water in a:
(iii) 9" grading to 11.5" enameled iron pot.

Flames beneath were all adjusted down to the pot's diameter, so all were different.

I didn't time anything but I was somewhat surprised to note the smaller enameled pot with lower flame came to boil before the larger aluminum pot with higher flame. Both had similarly warm water to start.

I would have thought it was harder to heft the heavier pot to temperature but I'm guessing their heating curves, while slower at first perhaps, are not the only story. Presumably the heat retention means the heavy iron holds and continues to heat hotter, and/or faster?

I guess this is all pretty interesting, though I suspect this is a well-known long-invented wheel, how a pot's qualities affect heating. While aware of these things, I hadn't realized how important the factors were.

Are any of our casual, non-controlled observations at all meaningful if initial conditions are so critical and finicky?

Follow-Up Postings:

RE: Boiling pan determinants

There is a lot more written about cookware on the net than about the burners. You are right there are many factors at work here. Just looking at one,the aluminum will conduct heat much better than the cast iron and will also radiate the heat from the sides so that is why it could take longer. There have actually been discussions that some think copper is not as energy efficient because it would conduct and radiate so much more heat than other pans--It sure is even though! One thing about learning about the properties of cookware is that you can learn what pans are best for what type of cooking. These different properties also make it difficult to judge the simmer setting on the various ranges. If you use cast iron, it will tend to hold the heat but if you use copper, it would tend to conduct and radiate the heat and make for a lower temp. The size and shape of the pot contribute to that as well. There are simmer plates made of copper and cast iron --one is going to be a lot better for diffusing heat.

RE: Boiling pan determinants

The specific heat of iron is about 1/9th that of water. If the water weighs the same as the iron pot, then about 90% of the energy heats the water, the other 10% heats the pot. As an example, a Le Creuset 5.5qt pot weight about the same as the water it can hold.

The specific heat of aluminum is about double that of iron, still much less than water. That means that an aluminum pot weighing twice as much as an iron pot would take the same amount of energy to heat -- but I expect the iron pot is more than 2x as heavy.

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