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Effect of color on heat transfer

Post in 'The Hearth Room - Wood Stoves and Fireplaces' started by pinefarm, Apr 24, 2006.

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  1. pinefarm

    pinefarm New Member

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    My question is: Does the color paint on the outside of a pipe or radiator affect the tranfer of heat out of the pipe or radiator. I have a friend who says black paint will make for better heat transfer. That, he says, is why car radiators are black. On the other hand, most old radiators I recall are painted white and the fins on my baseboard heaters are white Dave Johnson

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  2. Shane

    Shane Minister of Fire

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    That's not true at all. Heat transfer has to do with the density of material and nothing to with color.
  3. BrotherBart

    BrotherBart Hearth.com LLC Mid-Atlantic Division Staff Member

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    Damn! Ya beat me to it.
  4. berlin

    berlin New Member

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    i don't believe that color has any real effect on heat transfer, however certain coatings do assist in the transfer of heat, while others reduce the heat transfer, it may happen that certain coatings that happen to be black assist heat transfer, however the color itself doesn't have any effect.
  5. precaud

    precaud Minister of Fire

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    Yes, it does. This is covered nicely in the Solid Fuels Encyclopedia, page 101-102. Basically, avoid metallic paints and bare metal surfaces and you'll be fine. Nickel and chrome plating is the worst.
  6. elkimmeg

    elkimmeg Guest

    are you confusing heat absorption with transfere? Darker colors absorb heat better then lighter colors If one notices base board radiators they are lighter in colors for a reason lighter colors transmit heat better. Lighter colors also reflect heat better
  7. precaud

    precaud Minister of Fire

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    Sorry, this isn't true. They are lighter colors for esthetic reasons only. There's no difference in radiation transfer efficiency between lighter and darker colors, only between metallic and non-metallic ones.
  8. billoetjen

    billoetjen New Member

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    Any phycisists out there who can chime in with a discussion of "blackbody radiator"(s); that might shed some light (or heat) on this question.
    As far as I can remember, a black body both absorbs and radiates electromagnetic radiation (heat) the best.
    But as far as I can remember, as far as I can remember ain't that far.
    Bill
  9. Metal

    Metal Minister of Fire

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    If your stove is black, it radiates alot of heat, if it is orange, it radiates alot more, and when it turns white, look out!

    On a more serious side, two paints of the same type but different colors will radiate the same.
  10. Rob From Wisconsin

    Rob From Wisconsin Minister of Fire

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    I think you are confusing the heat that would be absorbed
    via "shortwave radiation" (i.e. - light). Radiant heat is classified
    as a "longwave radiation" type. I believe it wouldn't be
    significantly affected by color.

    My 2 cents worth.....

    Rob

    P.S. - The "coriolus effect" could factor-in here :>)
  11. Turner-n-Burner

    Turner-n-Burner New Member

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    Dammit - it's been a while - You made me dig out the heat transfer book!

    I think what the OP is really about is the "emissivity" of the surface in question. That is a coefficent applied to the calculation of radiated energy, and can range from nearly 0.0 for a highly polished clean metal surface to 1.0 for a optimized paint or anodized surface. Color, oxidation, and surface condition all effect the numbers in between. So in short, yes, color does have an effect on the radiated heat thrown off by an object.

    But - the typical term of radiator used for heating and auto radiators is patenly incorrect. The mechanism they use to extract heat is convection. If there is a fan attached to it, or you can feel air moving around it - it's not a radiator - it's a convector! ;) Color doesn't effect convection.

    -Dan
  12. billoetjen

    billoetjen New Member

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    AND less likely to get shot by a frustrated hunter!! :cheese:
    Bill
  13. wg_bent

    wg_bent Minister of Fire

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    So if a stove is painted white vs black vs chromed, the implication is that it radiates heat differently? If so, where does the heat go? up the chimney? Retained? So if it radiates less, then it must retain more heat, thus improved heat retention capacity? Like soap stone vs steel? I'd bet a lot that it's unmeasurable at the level of what a woodstove radiates over a 24 hour period.

    If color has an impact on heat radiation, then you'll need to let the folks at NHRA know cause getting rid of heat on a top fuel dragster's headers is really important when your generating 7000 horsepower and have a 7040 degree flame front. Some are chrome some are black.

    I think the bottom line is...Get the color you like.
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