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Post by ulrikf on Apr 2, 2016 0:35:40 GMT -8
Hi,
Would a copper pot be more or less efficient compared to an aluminium pot, when heating water on a Aprovecho style institutional rocket stove WITH a pot skirt?
I know that copper has better thermal conductivity compared to aluminium. But I've read that they might have different thermal radiation, which must also be considered?
How would the heat transfer be affected if there are oxide on copper or aluminium?
I know cooking in copper pots might not be healthy, but in my case the heated water is not for drinking/cooking.
/Ulrik
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Post by satamax on Apr 2, 2016 2:28:08 GMT -8
Aluminium pots are even worse healthwise. Best bet, steel!
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Post by ulrikf on Apr 2, 2016 6:59:16 GMT -8
Aluminium pots are even worse healthwise. Best bet, steel! Steinless steel would be better healthwise yes, but the thermal conductivity of steel is much worse, at least if the steel pot does not have an inner core of either aluminium or copper. Since I'm not going to drink or cook with the water, the health aspect is not an issue, and therefore I ask about copper vs aluminium efficiency? |
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Post by Dan (Upstate NY, USA) on Apr 2, 2016 17:37:55 GMT -8
I think copper has less thermal conductivity (by a little) but absorbs more of a range of the infrared spectrum, while aluminum has a better thermal conductivity but reflects some infrared. This is by memory of course, so I could be completely wrong. In the end I don't know which one would be more efficient. I bet in the end its a wash...
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Post by ulrikf on Apr 4, 2016 13:42:06 GMT -8
I think copper has less thermal conductivity (by a little) but absorbs more of a range of the infrared spectrum, while aluminum has a better thermal conductivity but reflects some infrared. This is by memory of course, so I could be completely wrong. In the end I don't know which one would be more efficient. I bet in the end its a wash... Copper has better thermal conductivity than aluminium. Regarding the absorption I don't know, but I guess it depends heavily on the amount of oxide. |
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Post by shilo on Apr 6, 2016 8:57:56 GMT -8
gold
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stoker
Junior Member
Posts: 61
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Post by stoker on Apr 14, 2016 14:53:17 GMT -8
For absorbing radiant heat, the condition and cleanliness of the surface is much more important than the metal. They're both reflective when clean and polished, but they'll get sooty and then their "emissivity" (which applies equally to absorbing radiation) will be high, close to 1.
As for conductivity, copper is better for a given thickness, but when it comes to pans you can find to buy, the thicknesses will be different.
I don't think it'll make much difference anyway: I would expect that for either option the temperature difference between the inner and outer surface of the metal will be very small. There will be a big difference between the air/smoke temperature 0.1mm from the metal and 1mm from the metal.
As for health issues, the main risk would be from cooking acidic foods/drinks in aluminium ware. Plain water being boiled should be fine.
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Post by mkrepel on Apr 18, 2016 16:19:09 GMT -8
I use a stainless steel pot with a built-in skirt. It works really well and I have no issues with using the water for cooking or drinking afterwards. I don't think you need to worry too much about the high conductivity metals when the entire bottom and sides of the pan will be surrounded by hot gases. The high conductivity metals (like aluminum and copper) are used to help equalize the heat across the bottom of the pan on modern stoves. I would think you could use anything with a rocket stove and it will work just fine. I have used many different kinds of pots over campfires over the years and sometimes they only boil on one side, but the water gets hot everywhere due to water's own ability to carry heat away from a heat source.
I would say get whatever you can get your hands on and can afford. They should all work well with a skirt and you will not be able to tell the difference between them.
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Post by wiscojames on Apr 19, 2016 8:41:16 GMT -8
mkrepel - If you get the chance, could you post a picture of your pot with built-in skirt?
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Post by mkrepel on Apr 19, 2016 13:40:59 GMT -8
mkrepel - If you get the chance, could you post a picture of your pot with built-in skirt? I bought it from Stovetek, but Silverfire also builds one. It is posted on their home page. With one of those and a rocket stove, I can boil 5 liters of water in about 12 minutes. It is the most efficient water heating I have ever done with a wood fired device. Here is a link to the Silverfire Dragon Pot: link. The thing isn't cheap, but nothing really is anymore; especially stainless cookware. |
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