[Stoves] radiant heat capture, total heat measurement
ajheggie at gmail.com
ajheggie at gmail.com
Wed Mar 14 16:46:07 CDT 2012
[Default] On Tue, 13 Mar 2012 08:36:41 -0300,"Kevin"
<kchisholm at ca.inter.net> wrote:
>
>One way to look at it is that "Blue Flames are too smart by half." :-) There
>is a gain in completeness of combustion, and probably higher temperature for
>"products of combustion", and reduced sooting of pots, BUT there is a
>significant loss in luminosity, and heat transfer to the pot by radiation.
>The Mesh Dome, heated by direct convection of the "blue flame" then is in a
>position to add a "radiation contribution" to heat transfer capability.
Yes
>
>It would be a very interesting experiment to take a "flame temperature" of
>Paul Oliver's system, with, and without the dome. My guess is that the
>"flame temperature" of the "Blue Flame", and the gases leaving the dome
>would be similar, and relatively low, even though the actual thermocouple
>measured temperature of the gases would be high. In very simplistic terms
>(for illustrative purposes only)
>1: Blue Flame temperature by radiation measurement: 1000
>2: Gas temperature above dome (radiation) 1000
>3: Thermometer temperature of both gases 1500
>4: Flame Emissivity of 1: and 2: .2
>5: Flame emissivity for luminous flame: .8
it looks like Paul has done thios now
>
>Thus, if some of the pyrolysis gases were diverted away from the "blue flame
>conditions", and were allowed to increase the flame luminosity, there could
>potentially be an opportunity to "have your cake and eat it." More
>specifically, the addition of some "luminous fractions" to the flame could,
>for example increase flame luminosity to say .6. but with a drop in actual
>gas temperature to say 1300 because of incompleteness of combustion.
The trouble is that could increase PICs leaving the flame unburnt.
>So.... if the concepts are correct, then it would seem that the best way to
>make a stove would be to make one with a burner that produced BOTH yellow
>flame(for luminosity) and a blue flame (for completeness of combustion).
Having got a good, short, premixed flame I wouldn't advocate going
back to a diffusion flame.
There is an example from the past where a chamical was added to town
gas to make a yeallow flame, I think it was called carburetted gas,
and a sall amount of petrol vapour was added to the CO+H2 mixture but
this was before gas manteles were available. I think gas mantles t=do
a better job as the light radiator because of the excitation
characteristics of thorium being better than glowing sooty particles.
AJH
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