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

[Kevin Adair]

The pot soot blackening pots is a major issue reducing adoption of many
non-carbonized biomass stoves in Haiti.

We hope to reduce the pot blackening with the nozzle design.
On Jan 11, 2016 9:03 PM, "Paul Anderson" <psanders at ilstu.edu> wrote:

> 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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