[Stoves] Feed Chamber Opening

[Xavier Brandao]

Andrew said: "If I remember correctly, the feed chamber opening for a rocket
stove is a function of the desired output, not the size of the fuel wood."
Yes the size of the rocket elbow, of the feed chamber and of the whole
rocket stove go up as the size of the pot goes up. So proportions are
respected.
There is a range of 7 combustion chambers covering all pot sizes. So there
are 7 sizes for the feed chamber opening: 22 X 22 cm, 20 X 20, 18 X 18, 16.5
X 16.5, 15 X 15, 12 X 12, 11 X 11. Even the biggest one doesn't allow big
logs use, users will have to chop wood.

"to choose an improved stove that will be a more appropriate fit.  The
rocket stove is not the only solution available."
Then which one? Almost all the institutional stoves I know are based on the
rocket technology. The Justa stove, the Rocket Lorena, the Rocket mud stove,
the institutional brick stove made by GTZ, and also, I think, the LEGO stove
have a small opening for wood. Even the Lion Stove has a 16.5 x 11 cm
opening, and the Esperanza, couldn't find any technical info, seems to have
a small opening. Could you please give me example of other stoves?

"another hospital was supplied with smaller diameter wood that fit the
stove."
For now yes, let's hope they don't change supplier.

I am not sure this issue appears with domestic stoves. Some of the
institutions use a great deal of wood, it is then more practical to deliver
them big logs than a very big number of small logs. Now, unimproved smoky
institutional stoves still have an advantage over improved stoves, their big
opening. They shouldn't have any advantage.

This is a message to Tom Miles: by the way, I just realised there was no
category on Bioenergylist for Institutional stoves. I think there is a need
for a centralized place on the web where all relevant information on stoves
for institutions can be found. Bioenergylist seems the most appropriate
since everything about stoves is to be found there already. I did spend some
time and efforts searching for institutional rocket stoves I could build,
collecting reports and info drop by drop, and I'm sure I miss a few good
info.

Xavier


------------------------------

Message: 6
Date: Fri, 08 Apr 2011 22:46:21 -0600
From: "Andrew C. Parker" <acparker at xmission.com>
To: rajan_jiby at dataone.in, "Discussion of biomass cooking stoves"
	<stoves at lists.bioenergylists.org>
Subject: [Stoves] Feed Chamber Opening, was Re:  Stoves Digest, Vol 8,
	Issue 11
Message-ID: <op.vtnl7gj1uoov7l at user-8ezctxe031>
Content-Type: text/plain; charset=utf-8; format=flowed; delsp=yes

If I remember correctly, the feed chamber opening for a rocket stove is a  
function of the desired output, not the size of the fuel wood.  One of the  
stated benefits of the rocket stoves need for small diameter fuel is that  
there is no need to cut down the entire tree for firewood.  As Xavier  
mentioned, another hospital was supplied with smaller diameter wood that  
fit the stove.  I suppose that this underscores the need to thoroughly  
examine the existing behavior, politics and infrastructure of the client,  
and, if it is obvious that there will be no willing changes, to choose an  
improved stove that will be a more appropriate fit.  The rocket stove is  
not the only solution available.

Having said that, based on this study from Aprovecho, ROCKET STOVES ?  
CONTROLLING DRAFT (Variations in chimney height and air flow openings in a  
modified ?rocket stove?.), by Damon Ogle, August 17, 2002, I have wondered  
if a rocket stove could be designed that controlled flue gas velocity with  
a choke at the top of the chimney (perhaps introducing preheated secondary  
air at that point, as with some gasifying stoves).  The sizing of the feed  
chamber opening may then not be such a critical factor.  Was there  
follow-up to that study at Aprovecho?


Andrew Parker (Not AJH)



On Fri, 08 Apr 2011 19:54:51 -0600, <rajan_jiby at dataone.in> wrote:

> Dear All,
>
> My question is :
>
> What would be an optimum size range for the feed chamber opening -  
> rather how small it can go upto ?
>
> Best Regards,
>
>
> Rajan