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Coaling stage efficiency

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by delp, Nov 15, 2012.

  1. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    Something that the articles never address is that when we reload on a coal bed we use a lot of the heat energy in those coals to drive the moisture off of the new wood that is in stage one of the burn instead of them providing heat to the living space.

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  2. Huntindog1

    Huntindog1 Minister of Fire

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    Check this out:

    http://mb-soft.com/juca/print/311.html

    It is also useful to note how these concepts apply to un-seasoned (green) wood fuel. If only seasoned a short time, 50% moisture is a realistic figure. Then a two-pound piece has one pound of wood fibers (worth 8660 Btu). There will be 1.54 pounds of water to vaporize and heat up (taking away 2200 Btu). The two-pound piece has a net available energy content of 6460 Btu or 3230 Btu/pound. This is only HALF of the available energy present when burning seasoned wood. Green wood consumes the bulk of its energy just to keep itself going, and is obviously subject to easily going out.
  3. Sprinter

    Sprinter Minister of Fire

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    Interesting numbers there, too.
  4. Flatbedford

    Flatbedford Minister of Fire

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    BB's article also doesn't really address how much heat secondary combustion makes in a modern EPA stove.


    "Secondary combustion can and does occur in wood burning stoves but probably only during very hot fires with just the right temperature and air supply"

    I think we'll all agree that secondary combustion is a huge part of the burn cycle and also makes a large portion of the heat generated by a stove. I know that my Fireview is putting out much more heat for the few hours of intense secondary burn than it is during the few hours when the charcoal is burning down.
  5. Huntindog1

    Huntindog1 Minister of Fire

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    Here is another bit of info for reference:

    http://www.engineeringtoolbox.com/wood-combustion-heat-d_372.html

    The Combustion Process of Burning Wood

    1. Wood heats up to approximately 212 oF (100 oC) evaporating the moisture in it. There is no heating from the wood at this point
    2. Wood solids starts to break down converting the fuel gases (near 575 oF, 300 oC)
    3. From 575 oF to 1100 oF (300 - 600 oC ) the main energy in the wood is released when fuel vapors containing 40% to 60% of the energy burn
    4. After burning fuel vapors and evaporated the moisture, only charcoal remains burning at temperatures higher than 1100o F
    • TC = 5/9(TF - 32) <===== I have no Idea what this means?
  6. Huntindog1

    Huntindog1 Minister of Fire

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    Flatbed,

    I think the thing to think about it there is only so much wood gas in a piece of wood. If you burn that certain amount of wood gas in the log it amounts to 40 to 60 percent of the heat in the wood. Your Cat allows you to burn a high percentage of that wood gas , hopefully almost all of it. When the cat goes less active towards the end of the burn cycle you have most likely burned all the wood gas out of the wood.
  7. Sprinter

    Sprinter Minister of Fire

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    That's the conversion formula Fahrenheit to Centigrade

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