[Stoves] Mixing array problem
Paul Anderson
psanders at ilstu.edu
Thu Sep 3 23:12:37 CDT 2015
Dear Kirk,
Please be reassured that innovative work by you, Julien Winter, and
others is GREATLY appreciated by all of us.
I have taken the liberty of posting your message (below) to the entire
Stoves Listserv. I hope that you and others will all do that in the
future, to reach a far wider audience. The Stoves Listserv has been an
EXTREMELY POWERFUL AND APPROPRIATE avenue for communications. Without
it, TLUD stove technology would probably still be almost unknown.
I hope that more people will participate with the Venturi gas mixing
initiatives. Please post to the Stoves Listserv.
Paul
Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
Email: psanders at ilstu.edu
Skype: paultlud Phone: +1-309-452-7072
Website: www.drtlud.com
On 9/1/2015 12:34 PM, kgharris wrote:
> All,
> My thoughts are that for over a century fossil gas fuels have had the
> advantage over wood stoves in that they could be premixed with air
> with a very efficient device called a Venturi gas mixer. A Venturi
> mixer lowers the pressure of one of the gasses by accelerating it. The
> higher pressure gas is brought into contact with the lower pressure
> gas, and rushes into it to equalize the pressure. The gasses are
> thoroughly mixed and are then ignited at a burner.
> Then Paal Wendelbo, Dr. Tom Reed, Dr. Ron Larson, Dr. Paul Anderson
> (Dr. TLUD), and other gifted experimenters developed the
> micro-gassifier stove. With this development it is possible to give
> wood stoves the same mixing advantage that fossil gasses have enjoyed
> all these years. A TLUD Venturi gas mixer would look much different
> than a fossil fuel Venturi mixer because fossil fuels start off cool
> and pressurized. This is not the case with the wood gas in a TLUD,
> which is hot and near atmospheric pressure. The device would have to
> change the pressure of one of the gasses, either the air or the wood
> gas so that the other gas will rush into it to equalize the pressure.
> One way this is possible is by accelerating the raising wood gas
> around an object such as a tube. As the wood gas moves around the tube
> it's velocity increases, and it's pressure decreases, according to the
> Venturi effect. Then the two gasses must be brought into contact with
> one another so they can mix. Openings in the sides of the tube at the
> point of maximum velocity of the wood gas, and thus it's lowest
> pressure, will allow air from inside the tube to mix with the wood
> gas. The air will rush out of the tube and into the wood gas to
> equalize the pressure, and the two gasses will mix. This operates in
> addition to the natural draft, giving the mixing an extra boost.
> Natural draft by itself does not create a pressure difference that can
> cause this type of mixing. Gasses brought together by natural draft
> have only a miniscule pressure difference and will have no motivation
> to mix except diffusion, which can be increased by turbulance. But
> diffusion mixing, even with turbulance, must be awfully good to
> aproach Venturi mixing.
> One commonly used type of fossil gas Venturi mixer allows pressureized
> gas to escape through a small hole. A stream of gas is created and
> accelerated to a very high velocity, and thus a very low pressure.
> This allows a small mixer to do considerable mixing. Accelerating the
> TLUD wood gas around a tube does not create such a large pressure
> difference. The pressure difference is less, so the design must
> include a lot of mixing area. A mixing array having a number of mixing
> tubes is necessary. This requires that the wood gas be spread across
> the entire array, so as to use the entire array and not overload or
> underload any part of it. This is the problem we are working on now,
> and I am trying the ideas you have given.
> Another advantage of using the array of tubes is that the wood gas is
> shaped into sheets as it passes between the tubes. These sheets are
> fed with air from the tubes from both sides. Thus the air only has to
> penetrate half the sheet of wood gas. This occurs all across the
> entire array, and makes the mixing very fast, such that it can work in
> a verticle distance of perhaps one half to one inch. The burning takes
> longer, but the mixing is fast. It can be seen as a blue flame at the
> tubes which turns yellow as it raises. Of course this happens only
> when the whole system is balanced and functioning properly.
> I have been working on the shoulders of the above mentioned giants,
> and much of what I have done is quite radical and so is not familiar
> to them. I have had to break away from their thinking at several
> points to follow these radical ideas. This does not mean that I do not
> respect them, it just means that I am adding my own little piece to
> the TLUD puzzle.
> Kirk
>
> ----- Original Message -----
> *From:* kgharris <mailto:kgharris at sonic.net>
> *To:* Steve Dixon <mailto:electrum at spiritone.com> ; Ricardo Luís
> Teles de Carvalho <mailto:rldtcarvalho at gmail.com> ; Paul Taylor
> <mailto:potaylor at bigpond.com> ; Jon and Flip Anderson
> <mailto:ogilvia at gmail.com> ; Julien Winter
> <mailto:winter.julien at gmail.com> ; Huck Rorick
> <mailto:community at groundwork.org> ; Art Donnelly
> <mailto:art.donnelly at seachar.org> ; CHRISTA ROTH
> <mailto:christa-roth at foodandfuel.info> ; Cody Anderson
> <mailto:cody.anderson at scottsdalecc.edu> ; Saloop T S
> <mailto:t.s.saloop at gmail.com> ; Sam Bentson
> <mailto:sbentson at aprovecho.org> ; Paul Anderson
> <mailto:psanders at ilstu.edu> ; Ronal W. Larson
> <mailto:rongretlarson at comcast.net> ; Dean Still
> <mailto:deankstill at gmail.com>
> *Sent:* Friday, August 28, 2015 1:13 PM
> *Subject:* Mixing array problem
>
> All,
> Greetings and best wishes.
> I have been working to try to get higher power levels for the
> Wonderwerk Strata combustor I have been working on with some
> success. A problem keeps popping up, and I was hoping to get some
> feed back from you. The problem is that the flame tends to the
> middle of the mixing array (see attachment photos of the bottom
> side of the test combustor). This leaves the center area
> overloaded and the outer area unused, but the flame needs to be
> spread evenly over the entire array. I am not certain why this
> would be so pronounced. I have minimized the secondary air
> comming in from the outer edge of the stove, which might blow the
> gasses to the center, but the problem persists. I have tried
> several other ideas one of which you can see in the pictures,
> widening the center to of the tubes to create more flow resistance
> in the center forcing the flame outward, which worked some. Any
> ideas?
> Kirk
>
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