[Stoves] Mixing array problem

Paul Anderson psanders at ilstu.edu
Thu Sep 3 22:12:37 MDT 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.


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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