[Stoves] Airflow For Biomass Fired Appliances- Natural Draft Stoves

[LANNY & ANNETTE HENSON]

Thanks Dean,
That was helpful especially the flame color 

>The very hot yellow/white flames easily make black carbon.
>The less hot deeper yellow/red flames make less/no black carbon.and everything 
>else make since.
Lanny




________________________________
From: Dean Still <deankstill at gmail.com>
To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>
Sent: Sun, April 14, 2013 2:53:59 PM
Subject: Re: [Stoves] Airflow For Biomass Fired Appliances- Natural Draft Stoves

Dear Lanny,

Hope you get better soon!

Here are the design principles I use to tune a stove (same for Rocket, TLUD, Fan 
stoves).

I imagine that to get clean combustion all of the gases and smoke are forced to 
enter the flame.

Then the gases and smoke stay in the flame long enough to be burned up.

The very hot yellow/white flames easily make black carbon.

The less hot deeper yellow/red flames make less/no black carbon.

Draft is decreased or increased until the right amount of gas and smoke is 
delivered to the flame for the right amount of time.

Draft has a lot to do with the correct metering of fuel (gas and smoke) into the 
flame: how fast gas and smoke is made and how much flame is made. I think we 
want lots of flame but only the right metered amount of gas and flame to enter 
the flame. 

Lengthening the time for combustion in the flame is good when: the metering of 
fuel stays right,  the air/fuel ratio stays right, and losses through the stove 
body do not increase too much (good insulation.)

Flame is needed to combust smoke and gas.

Something like that.

Best,

Dean




On Sun, Apr 14, 2013 at 11:25 AM, Alex English <english at kingston.net> wrote:

Lanny,
>I understand the comment below but I think flame height can be       shortened 
>with excessive excess air. The lowest emissions CO/CO2       and highest 
>temperatures, at some power levels, in appliances that       I have tested has 
>often been when there is a significantly taller       tail of flame. 
>
>
>However, don't believe  all tall tails :)
>Alex
>
>On 14/04/2013 1:51 PM, Lanny Henson wrote:
>
>
>>The combustion air needs to be focused on the         combustion zone in a way 
>>that shortens the flame height. More         like the way a TLUD with a fan 
>>works.  
>>
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