[Stoves] burning woodgas

Tue Aug 3 09:08:14 CDT 2021

To the practitioners of the combustion arts and sciences.

Overwhelm or pre-empt convective and  tangential tendencies. Accelerate the
molecular bundles to crash as if an all point automobile assault on an
unexpected traffic circle or roundabout. Pure Hollywood carnage, but
instead of a big orange flame you get a faint blue one.
Cut. Cut.

If the Arc de Triomphe were La Flamme de Triomphe and all the cars were air
molecules rushed radially to the center....
[image: arc.jpg]
then you have the large version of a
Candle In The (Focused )Wind,
a 60 second attempt at explanation and demonstration.

https://www.youtube.com/watch?v=ucCl0aGLqc0

Cheers,
Alex Anglais

On Mon, Aug 2, 2021 at 6:08 PM Harris, Kirk <gkharris316 at comcast.net> wrote:

> All,
>
> I believe Julien is correct about how clean stoves can be dangerous.  They
> seem harmless since there is not smoke or smell, and so might be brought
> inside with no ventilation.  They still produce CO2, no matter how clean
> they are, and could cause asphyxiation.  I have given that warning to those
> who have looked into my designs.  It may seem harmless, but can be harmful
> if used improperly.
>
> I was told early on in my efforts that TLUDs are good at burning smaller
> particulates.  This would make sense because the particulate would burn
> from the surface to the center, and in a small particulate that is not very
> far.  I can see two sources for small particulates; particulates which are
> not sufficiently mixed, and large particulates which burn from the surface
> too the center and don't quite finish burning.  These would result from
> inadequate mixing and inadequate dwell time.
>
> The study of pressure variations in TLUDs seems not to have occurred
> substantially.  My efforts are perhaps a humble beginning on this topic.
> The initial pressure variation in a TLUD is created by the density and
> weight of the gasses inside the stove vs. the density and weight of the
> gasses outside the stove.  The lower density, lighter weight hot gasses
> inside the stove are displaced upward by the higher density, heavier cool
> atmospheric air.  This is called draft, or more generally, buoyancy.  Once
> the gasses are moving, they display the Venturi effect, the exchange of
> energy between pressure and velocity.  The higher velocity gasses have
> increased kinetic energy, and lower potential energy stored in pressure.  I
> visualize it in my mind as being like cars stopped at a red light, they are
> close together.  Once the light turns green the first car goes before the
> second which goes before the third.  As they accelerate they separate,
> having more space between.  I see the particles of gas in the same way, and
> so by this mechanism pressure and velocity can exchange energy.  In the
> burning concept I am working on, the lower pressure wood gas is accelerated
> (lowering its pressure still further) and the higher pressure secondary air
> is slowed (increasing its pressure), and so the pressure difference and
> pressure driven injection of one gas into the other is increased.  In a
> stove that accelerates the secondary air, such as the common design that
> uses holes to jet streams of air into the column of wood gas, the increased
> velocity of the secondary air lowers its pressure, and the pressure
> difference between the gasses is decreased.  It may even be possible to
> lower the pressure of the secondary air to or even below that of the wood
> gas.  This loss of pressure difference will hinder pressure driven
> injection.  Such a system is relying more on surface contact and diffusion
> to mix, and will work, but wastes much of the pressure driven injection.
> It will not have the range of clean burning power levels of a system that
> takes into account the pressure variations.
>
> Kirk H.
>
>
> On 8/1/2021 9:45 AM, Crispin Pemberton-Pigott wrote:
>
> Dear Julien
>
> You are on the right track with the ventilation, in my opinion,  however,
> there misinformation about regarding nanoparticles. (Real ones)
>
> Below a certain size nanoparticles and inhaled and expelled again. They
> pass into the cell walls by diffusion, not by being trapped in the usual
> manner. The particles of concern are between 0.1 and 4.0 microns. It is
> true that the 0.01 micron particles are emitted when the combustion is very
> clean, however their role in disease is not at all clear, compared with the
> larger "respirable" set. It is a very active topic of interest.
>
> My caution is not to take every alarming claim at face value. There are so
> many vested interests seeking funds. If all combustion was totally clean,
> there would be nearly no rain. Think about it.
>
> Best regards
> Crispin heading to Val Quentin
>
> *From:* winter.julien at gmail.com
> *Sent:* August 1, 2021 6:34 AM
> *To:* stoves at lists.bioenergylists.org
> *Reply to:* stoves at lists.bioenergylists.org
> *Subject:* [Stoves] burning woodgas
>
> Hi folks;
>
> The emission of nano particulate matter from open-mouth TLUDs has always
> been a big ethical bother for me.  The 'cleaner' we make TLUDs, the more
> dangerous they become if they are treated as 'safe' by the users.  In that
> respect, emission of some smoke from a TLUD at startup and flameout could
> be a good thing if it discourages stove users from cooking in poorly
> ventilated conditions.   In Bangladesh, I have been encouraging the
> development of fume hoods and the incorporation of TLUDs into chimney
> stoves.
>
> Cheers,
> Julien
>
> --
> Julien Winter
> Cobourg, ON, CANADA
>
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