Dear A.D. Karve,
Nice to hear from you,
and as well your interesting comment.
-I meditated a little bit about.
There are in general a lot of stove-experiments that fail by the wrong fuel, or
by the wrong stove for the chosen fuel; naturally often found by my own made
experiments.
Your comment reminds me to the fact, that wood isolates very well heat _and_
it staples lots of heat as well.
- e.g. There are now in Switzerland wood-covers for buildings available, which
mitigate the heat-entrance as well as dispatching the heat over several hours,
in times after sunshine, when desired.
When we have small particles, they get quickly lighted. Before lighting they
cannot transport much heat to the "cold side" or the cold "big mass" inside of
the particle because of their smallness.
I see at least two other effects which make a better and clearer burn in a
saw-dust-stove with small particles.
-Without respect to possible different energy-content of wood and straw, which
I guess, not know-.
The particle _shape_ of saw-dust does not reduce the air-flow-speed on its
surface as much as the straw does.
When the saw-dust particle has gassed out, it glows. In that moment there is
very much oxygen around it, compared with big charcoal-particles. -We know all
the short bright glow from starving charcoal-particles, due to that effect.
In the central hole of the saw-dust stove, the smother surface of saw-dust
allows a quicker draft close to the surface of the pressed wood-particles than
the packed straw does.
Every small particle is outgassed very quickly and the small particle profits
from its absolute _and_ relative small need of oxygen to glow bright. On the
other side, the next particle is not very distant and profits from that
brighter glow, to heat up, out-gass and glow then as well. I have no numbers,
but in so small dimensions half a millimeter is a big difference in radiation.
You mention leaves of trees, which do not burn properly. Certainly they have a
lower energy. But their two-dimension-extent causes, that the air must stream
tangentially, with the effect, that there is a lot "used/consumed" air. The
outgassed sheet of charcoal has not the effect of last-bright-glow and does
not force the other fuel to heat up and burn-
Those meditations are not very originally, but I hope, worth to remind.
-These thoughts led me since a lot of time, to change not only the thickness of
the kindling for my room-heating-stove, but as well its shape. But that is
another declination of likely facts.
-It seems the Deom-stove is as well capable to burn saw-dust in an acceptable
manner. That stove makes forced draft by a blow-tube onto the saw-dust-surface.
Kind regards
und herzliche Grüsse aus der Wetterau!
Martin
Message: 5
Date: Fri, 19 Apr 2013 06:19:38 +0530
From: Anand Karve <[email protected]>
To: Discussion of biomass cooking stoves
<[email protected]>
Subject: Re: [Stoves] The Art of Using Grass Bundles in TLUD Stoves
Message-ID:
<cacpy7sekuk0uvpuubkeksuj-5nrq_9wt5ia8wrd6ksrxkdp...@mail.gmail.com>
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Dear Martin,
we did a lot of experiments with the sawdust stove developed by my
daughter. It turned out that the particle size of saw dust palyed a
crucial role in its working. When tested with straw or leaves of trees
as fuel, it produced copious smoke. We got a smokeless, near-blue
flame only when we packed it with saw dust of a relatively small
particle size.
Yours
A.D.Karve_______________________________________________
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