[Stoves] Nozzles for TLUDs Re: venturi system -ratios of air and gas?

[Paul Anderson]

Julien,

I really like the potential of you counter-current entry of secondary 
air (before the air enters into the chamber;  not downward inside the 
chamber).

But the Adair variation has the secondary air entering laterally and 
mixing in with the gases.   But the downward side of the hourglass 
requires that the air/gas mixture (which could be flaming) must move 
downward that inch or two to go under the lower lip of the hourglass.

So it is not the same as your counter-current.  The two approaches could 
be combined, if desired.

Does the hourglass work?  Kevin's experiences indicate that it helps 
reduce blackening of the pots.   Work needs to be done.

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 1/11/2016 7:47 PM, Julien Winter wrote:
> Hello Paul;
>
> If I understand your description of Kevin Adair's burner, lowering an 
> hourglass restriction to the level of a concentrator would directed 
> secondary downward against the upward flow of the woodgas.  We would 
> no longer have a cross current burner.  We would have a counter 
> current burner.  A simple demonstration can be seen here: 
> https://youtu.be/RnVaHpLZg8U
>
> If we have a counter current burner, then there would be good 
> turbulent mixing of air and gas at the base of the gas flame. That is 
> where most of the work of the burner would be done.
>
> Research in Australia showed that when the aperture of a concentrator 
> ring was reduced below 70% of the reactor area, the gasification rate 
> started to decrease.  If an hourglass constriction functioned the same 
> way (and since we have a counter current burner, the conditions are 
> not the same) it could add some stability to the performance of a 
> counter current burner.  In an open riser, a counter current burner 
> can create a strong draft of primary air, and cause an excessive 
> gasification rates.
>
> I have measured soot deposits on pots when a using a concentrator ring 
> that I did not see with more open burners. However, a concentrator has 
> sharp edges that can create turbulence and flame stress that may not 
> occur with a smoother restriction, like an hourglass.
>
> I will have more to say about counter current burners in a few days.
>
>
> Cheers,
> Julien.
>
>
>
> -- 
> Julien Winter
> Cobourg, ON, CANADA
>
>
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