In a normal fireplace with normal wood, on average what temperature would a plate be under the burning wood?

Discussion in 'Highly Technical' started by superHARD, Dec 27, 2006.

  1. superHARD

    superHARD Diamond Member

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    Kind a long question, but if you put a plate under a burning log in a fireplace, how hot would that plate get?

    "very hot" and "real hot" answers need not respond please :)
     
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  3. oynaz

    oynaz Platinum Member

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    Does the log touch the plate? What is the plate made of?
     
  4. superHARD

    superHARD Diamond Member

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    Yes it touches the plate.

    Metal plate
     
  5. superHARD

    superHARD Diamond Member

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  6. CycloWizard

    CycloWizard Lifer

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    I would think that it would depend on the type of wood, as the chemical composition of woods differ considerably. The 1500°F neighborhood sounds like it's in the right ballpark though.
     
  7. TheoPetro

    TheoPetro Banned

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    does the mass of the log come into play here? I would guess it would matter the type of material the plate is, the type of wood, the mass of the plate, air currents, volume of fireplace, and mass of wood.
     
  8. Megamixman

    Megamixman Member

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    I think the mass of the wood would only come into play only under the circumstance where it is not enough fuel to put the plate into thermal equilibrium. I don't think we need to worry too much about the chemical composition of the wood, but more so rather the material that the plate is made of.The mass of the plate is important; the volume of the fireplace would be important if it could act as a restricting factor in the airflow.
     
  9. superHARD

    superHARD Diamond Member

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    1000-1500 F is my answer...at least it's close enough.

    If your leaving a plate in a fire, why does it matter what the plate is made of (as long as it would burst into flames or something)?
     
  10. Cogman

    Cogman Lifer

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    I was going to try and refute you but really its a good point. The only problem is if you have a material like clay then it wont get as hot as metal would before the log completly burns out. however with metal the tempatures should stay roughly the same with little to no variation. The main question is what kind of wood do you have as diffrent material burn at diffrent temps as well the construction and aid of devices like catalitic converters all play a role in how hot.
     
  11. wwswimming

    wwswimming Banned

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    when i started making jewelry i did it the "old-fashioned" way,
    using iron molds in an oak or pine fire.

    i had only 2 successes. the mold was in the shape of a cross.
    the pellets i used melted completely into the shape of a cross;
    the top is kind of rounded.

    silver melts at about 1700 F i think.

    the oak fires worked better than the pine fires (hardwood
    burns hotter than softwood.)
     
  12. foges

    foges Senior member

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    Material of plate has no effect on final temperature, only on time and amount of wood needed to heat the plate.

    Does wood have a specific temperature at which it will always combust (ie no varience)? or can it go to infinity if you varied the factors such as:
    Efficiency/rate of combustion of wood
    Chemical structure

    So if you combusted wood super efficiently (tons of oxygen, lots of surface), it would just release an large amount of energy which would the be distributed in its surroundings and with more energy comes more heat.
     
  13. bobsmith1492

    bobsmith1492 Diamond Member

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    We had a fire once where it melted the glass out of our fireplace doors...!

    I came home and there were two big blobs where the windows had been. Fortunately, someone was home to move the table and furniture away. I think it was a massive birch stump (not split) we were burning.
     
  14. WHAMPOM

    WHAMPOM Diamond Member

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    Metal conducts and absorbs heat easily. Ceramics won't, insulator
    I would guess 500 degrees tops. Not enough to get red hot, since heat rises and the incoming draft feeding the flame would cool the plate.
     
  15. cougar1

    cougar1 Member

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    For an upper limit, you can use the adiabatic flame temperature. This is a theoretical number calculated by assuming that all of the heat produced by combustion goes into heating just the combustion products (the gases released upon combustion) with no losses. Essentially, this is the highest temperature that can possibly be achieved anywhere within the flame. According to http://www.doctorfire.com/flametmp.html , the adiabatic flame temperature for wood is about 1977°C. In reality this number will depend a bit on the type of wood and especially the moisture content (higher moisture leading to lower temperatures).

    For your situation the temperature will be significantly lower, as most of the heat will be carried up through the chimney with the combustion gases and a significant amount will be radiated out into the room surrounding the fireplace. According to the reference above materials in housefires usually are below 1093°C, so even this would be a safe upper limit. As for the lower limit, that depends a lot on the materials involved, duration of the burn, and many other factors. In the extreme case of burning the top surface of a relatively thick log, the temperature may never get much above room temperature, since the log will essentially block any heat transfer to the plate below.

     
  16. StopSign

    StopSign Senior member

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    Guys, let's stick to Centigrade here. None of that Fahrenheit stuff.
     
  17. RossGr

    RossGr Diamond Member

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    The color of the plate is a direct indication of its temperature. I did a quick search and found this chart match the color of the plate to the color on the chart to get its approximate temperature. To measure temperatures in this range you can use a device called an optical pyrometer which uses this phenomena.