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How practical is using bismuth for stovetop heat transfer? Answered

A stove that heats pots by induction is a nice idea, but it is still not common and will not work with all pots.

Suppose, instead, the pot and resistive heating element were placed in a well that was filled with bismuth or another metal that has a low melting point. How would the efficiency of this compare to a pan sitting on an induction cooker, gas stove, or ordinary resistive heating element? What would be some important practical considerations, if this were implemented?



Best Answer 9 years ago

I don't know for sure about efficiency, but I would guess that the conductive efficiency would be relatively high.

Practical consideration: even bismuth, with a "low" melting point, would have to be above 520°F to remain liquid. This means that you would have a well filled with very hot metal, which would very easily burn a hand accidentally placed in/on it. In addition, it would remain hot for a long time after turning off the heat source, due to the high thermal mass of any metal, particularly bismuth. Finally, if you wanted the metal to be molten, you could not have a "low heat" below the melting point of that metal.

I'm not trying to discourage you, it's an interesting concept. However, it seems to me to be inherently dangerous, and would require extensive safety precautions.

. It doesn't seem to me that it would be that much more efficient at heat transfer than just sticking the pot over a "regular" heating element and insulating the pot. At least not enough to compensate for the difficulties and dangers involved with using molten metal, especially in an open vat. . You will lose a lot of energy melting the metal each time and then lose more when you have to remove the pot before the metal freezes. . What to do with the bismuth that sticks to the pot?

Eh pools of molten metal? Practical, always... Actually one day while incredibly bored I considered attempting to coat my kitchen floor in bismuth, to see if I could, however I do know it can be very unsticky and it's not toxic to the best of my knowledge, could you fry food in metal?

Insulating the pot does seem the most practical solution. The comment about heat capacity is important; it is good from a cooking standpoint but bad from a safety one. And I hadn't even considered the heat of fusion. Perhaps a flame-retardant synthetic oil would be more appropriate. There are nontoxic metal alloys that melt below the temperature of boiling water, but they aren't cheap. I agree that one would need a very good reason to overcome the safety considerations of working with molten 521F degree metal. I won't be trying or reommending this for cooking anytime soon.

Heat transfer would be grossly more efficient, but as mentioned, heat storage and practicality are out the window. Surface area of a liquid touching v. surface area of a conductive element is a pretty big difference. Inductive cooktops are HUGELY more efficient, but as mentioned dont work with all pot types.