*Ron,*
* I look forward to hearing Jim's, or anyone else's approach to the
difficult problem of accounting for the energy. Whoever comes out with a
method there will be another right around the corner. This is non-ending
so there is no need to wait. My suggested approach is not a comparison
-- just a different way of looking at it. Hopefully one that will work
without all the errors regarding calculating the remaining chars.*
[*RWL: One measures, not calculates the "remaining chars". Can
be pretty accurate - especially with TLUDs.*
*But why bother? All the heat from carbon carbon bonds stays in the
stove body and does not heat the water. *
**
*I am thinking of a new approach where we do not need to handle char at
all. I noticed when using the GEK and Tom Reeds TLUD that when fresh
biomass ran out the secondary flame went out, or very poor flame. Just
add more biomass and you are in business. *
*[RWL: This is not normally done at all with TLUDs. It is possible
with BLDDs.
*
*True - but we still can use the approach I propose. We keep track of
the fraction of biomass that turns into tars from the pipe method.*
**
*Hot coals several inches below the pot did a poor job of heating the
pot -- so why even consider them? *
*[RWL: Right. One of the main purposes of TLUds is to stop the
operation when the pyrolysis front hits the bottom.*
Perfect for this test
*Its only the fresh tars that heat the pot and all that other energy
just heats the stove body. Important to heat the stove body and aid in
breaking the bonds to release lumps of tars and complex organics free to
head to the secondary. But IF (Big IF) they do not significantly heat
the pot we can rule them out it saves that problem of all the difficult
calculating. *
*[RWL: If one purpose of the char was to make char, the measurement
and calculating is relatively trivial.
*
*If we do, or do not make char doesn't matter. If we re-use the char or
add the char produced to the next stove - it doesn't matter because it
does not heat the water. *
**
*If you were to fill a rocket with char and blast air on the char would
you get a secondary flame?*
*[RWL: Yes. This was demonstrated nicely at Stove camp by Kirk
Harris, who had a special set of "intermediate" holes - so as to burn
the chars nicely - from the top down.
*
*If this is true of a typical stove - my idea is not valid. But you say
a "special set of holes". And I believe for it to work the temperatures
of the char would need be >800c to produce the CO to add to the tars. I
think this would supply only a small (relative to tars) amount of the
energy for the secondary and only under special conditions. But I am not
yet sure I am right on what I propose based on this. *
**
*The stove body would get red hot but the pot only a few inches away
would heat up slowly without the flames licking the bottom. Lots of
useless heat.*
*[RWL: Nope - Kirk had a nice flame. His was a camping stove and not
interested in producing char. Very clever mod.*
I had my GEK really 'cooking' with forced air and when the biomass ran
out the flame was a nice blue color, still burning at the secondary and
the stove body got so hot it melted two bolts. But normal conditions
(less cigars & wine!) the secondary would go out unless you shook in
more wood chips.
**
*The question is can we take a block of wood and determine the weight
fraction that will contribute to the secondary? And the fraction that
sits with combustion in the stove body? I think the pipe will do that.
Once above 450c the char weight changes only a small amount with
increased heat meaning the carbon is attached as a lattice. In the real
workings of a stove we add oxygen to produce more CO from the char than
in the pipe but is going from CO to CO2 providing a large percentage of
the heat for the water? and how would we find that out?*
*[RWL: It might do it if you could **reproduce all the stove operating
temperature history. Running at high power will expose the biomass/char
to higher temps (and less char) than if the run was all at low power.]
*
*Just because there is less char doesn't mean the char that burned did
anything to heat the water. It just heated the stove body. The C-C bonds
are not volatile (?) until they *react with oxygen to form CO or CO2.
Then they can join the secondary gases.
Thanks
Frank
**
* Ron*
**
*Something different to talk about.*
**
*Thanks Ron for the reply.*
**
*Regards*
**
*Frank*
*Frank Shields*
*Control Laboratories; Inc.*
*42 Hangar Way*
*Watsonville, CA 95076*
*(831) 724-5422 tel*
*(831) 724-3188 fax*
*[email protected] <mailto:[email protected]>*
*www.controllabs.com <http://www.controllabs.com>*
**
**
**
**
**
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**
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