[Stoves] Metal screen (gauze) after burner on a natural gas flame

[Crispin Pemberton-Pigott]

Dear Martin

 

Thanks so much for that third link. It is a good example of a setup up
designed to improve the system efficiency. It has Lambda control (excess
air) and there is a little graph showing the EA+1  (λ). They are targeting
30% excess air. That, plus the used air = 1.3 as shown on the chart.

 

This low level of EA can be achieved with gaseous fuels and with more
difficulty, some solid fuels if they are predictable.

 

If you are shooting blind with a new design, I can suggest that you try for
80-120% excess air for coal and wood, and 50-100% for other fuels. Wood can
burn really well at 50% but most stoves can't maintain that level.

 

With a gasifier you should be able to get to 50% but the gas is likely to be
variable and it may not support a clean burn all the time. I have been very
recently working on a downdraft coal stove that seems to work best at 35-40%
which was a surprise, actually. That is low for coal. It has a lot of strong
mixing in a confined space which may explain it. 

 

The very short flames shown at
http://www.heizungen-wulfert.de/heizung_gasoel.html are because the fuel is
made of very short HC chains.

 

The animation is at
<http://www.viessmann.de/de/flash/animation_lambda_pro.html>
http://www.viessmann.de/de/flash/animation_lambda_pro.html

 

Regards

Crispin

 

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