[Stoves] Charcoal Rocket Stove

[Dean Still]

Dear Paul,

In a Rocket type combustion chamber I have not seen a benefit from adding
secondary air (another air source introduced above the fire). The primary
air/gases get hotter without adding secondary air. And there is enough
oxygen left in the primary air to combust gases above the fire. So far, my
experiments have only shown a decrease in temperature when adding secondary
air without a decrease in emissions. In a T-LUD secondary air is necessary
because there is little primary air but so far I have not seen secondary air
improve the Rocket.

You said, "Essentially, secondary air is entering via the
primary air openings." I agree with your idea but I think it is less
confusing to say that primary air is sufficient to create combustion in the
entire insulated space. 

Best,

Dean

-----Original Message-----
From: stoves-bounces at listserv.repp.org
[mailto:stoves-bounces at listserv.repp.org] On Behalf Of Paul S. Anderson
Sent: Saturday, April 28, 2007 7:00 PM
To: Discussion of biomass cooking stoves; Thomas Reed
Subject: Re: [Stoves] Charcoal Rocket Stove

Stovers,

> Dean Still wrote:
snip--
>> The Rocket was fastest because there is a lot of draft resulting in
higher
>> power. I have observed that emissions do go down in a Rocket type stove
>> AFTER the chamber gets hot AND when there are air holes between the
chunks
>> of charcoal. I did not see any additional benefit to adding secondary
air.

A hot chamber will result in a stronger draft, meaning more O2 (in air) 
getting
to the carbon with a better chance of getting more complete combustion (more
CO2 and less CO ).

When there are air holes between the chunks, there is a better chance for
some
of the O2 in the air getting past the hot char and therefore becoming 
available
O2 for secondary combustion.  Essentially, secondary air is entering via the
primary air openings.

If you have a hot fire of charcoal, SOME secondary air is essential to
combust
the created CO (to make CO2).  Starve the secondary air in the device and
you
will have higher bad emissions.  And if the CO gases are too cool when the
secondary air enters (and/or if there is no spark/flame present), the CO
will
not ignite, again resulting in poor emissions.

I assure you that the above paragraph is true.  And it is easier said 
than done,
ESPECIALLY when trying to do it in the small sizes of cookstoves.  If 
this task
were easy, it would have been accomplished a long time ago.  Keep trying and
best wishes for success!!!!

Paul



----------------------------------------------------------------
This message was sent using Illinois State University Webmail.



_______________________________________________
Stoves mailing list
Stoves at listserv.repp.org
http://listserv.repp.org/mailman/listinfo/stoves_listserv.repp.org
http://www.bioenergylists.org