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

[Julien Winter]

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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