[Gasification] Autopyrolysis Biochar - question on the wet newspaper
tombreed2010 at gmail.com
Thu Dec 26 11:45:44 CST 2013
Jon and All
I don't have any exact knowledge of the thickness of paper required to quench a pile of Autochar, but I think a saturated New York Times Sunday Edition should have enough water to put out any fire burning above it.
After all, after the fire has passed through a layer, no more oxygen can reach it because the next layer gobbles up all the O2. AND the upper layers are all cooling by BLACK BODY RADIATION, which increases as the fourth power of temperature even though they are still heated from below.
The BB radiation is,according to the Stefan Boltzmann law,
The Stefan–Boltzmann law states that the power emitted per unit area of the surface of a black body is directly proportional to the fourth power of its absolute temperature:
where j*is the total power radiated per unit area, T is the absolute temperature and σ = 5.67×10−8 W m−2 K−4 is the Stefan–Boltzmann constant.
For us (Surviving) mortals, this says that a black body (like charcoal) emits 5.67 T^4 Watts/cm2
but be sure to add 273 to the centigrade temperature, since T is the absolute temperature, in degrees Kelvin.
For charcoal at 500 C it would be
Radiated Power = 5.67X 10^-12x(500+273)^4 = 2.02 Watts/cm2
Not a lot, but there are a lot of cm2! , so don't stand too close. (Assuming I calculated correctly.)(I divide the 773 by 1000, raise 0.773 ^4 and multiply by 5.67, and avoid the 10^-12 this way. A square meter surface at this temperature would radiate 20 kW! Toasty!
In case you haven't guessed it, my degree is in Physical Chemistry, which deals extensively and intensively in this stuff.
(In case this were not a black body, it would have an emisivity in the SB equation, the power emitted by the body compared to that of a true black body. Charcoal is the only substance which comes close to having an emisivity of 1.00. )
Dr. Thomas B Reed
280 Hardwick Rd
Barre, Ma 01005
> On Dec 24, 2013, at 5:59 PM, Jon <rcwarship at comcast.net> wrote:
> Heya Tom Reed,
> Thanks so much for the newspaper idea. I'm using a toplit updraft (55 gallon barrel), and was wondering how much newspaper are we talking about? I assume that it would be kept in sheet form & not balled up?
> Thanks in advance for the advice.
> Merry Christmas To All,
>> On 12/24/2013 2:02 PM, Tom Reed wrote:
>> Toplit updraft
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