[Stoves] Improve gas burners efficiency?

[Crispin Pemberton-Pigott]

Dear Xavier

Gee, it would be easy to add a skirt to that rim-stove. It already has a lip
to hold it in position! You should check that the vertical 'chimney effect'
does not drive a lot of extra air through the stove, cooling the gases. If
you painted the outside silver it would keep the radiation of heat down from
the rim.

You could put clay /sand into the base leaving only enough room to get air
in and distributed around the burner. This is a great place for a combustion
analyser. Put on a skirt and measure the excess air coming through and close
the hole until it is about 25%. Probably reduce fuel consumption
considerably and increase the heating speed. It is really hard to guess what
the EA is by looking at a gas flame.

Regards

Crispin

 

From: stoves-bounces at lists.bioenergylists.org
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Xavier Brandao
Sent: 29 July 2011 15:00
To: stoves at lists.bioenergylists.org
Subject: [Stoves] Improve gas burners efficiency?

 

Dear stovers,

 

When promoting the institutional rocket stoves in public administrations
kitchens, restaurants, hotels in South Benin, mostly in the cities of
Cotonou and Porto-Novo, I am told more than once that wood is not used
anymore, because of the smoke, the cost, or the hassle. Many moved to gas
burners, which is of course great. We produce and sell wood stoves, but we
always encourage people to use gas cookers, because they are cleaner, more
ecological and economical. We only produce wood stoves for people who would
have use wood for cooking anyway (for certain dishes, certain quantities, or
in certain big institutions).

 

Many people liked the sturdy design of the stoves and asked if they could
have the same for gas stoves. I always reply that is was designed for wood
only, and promise we'll think about a model for gas burners.

 

My question is: how much can a gas burner be improved in terms of energy
efficiency? Is it worth spending metal in making a skirt around the burner
and the pot? I was thinking also of a surface under the burner, perhaps just
like the institutional stoves, made of a mix of clay, to radiate heat
upwards. It would give a traditional look to a modern cooking device.

 

My quick calculations showed it could cost in the very very worst case up to
30 000 CFA francs all included (about 45 euros) for a skirt for one burner.
People seem to be ready to pay that, if it means savings. A lady who runs a
restaurant paid a welder 60 000 CFA for two skirts, which amusingly enough
is in line with my calculations. They are not made yet, I'm curious to see
how they look.

 

Here is a picture of the burners:

http://imageshack.us/photo/my-images/803/rimg1222.jpg/ 

Another burner, inserted in a truck rim:

http://imageshack.us/photo/my-images/834/rimg1229.jpg/ 

Here is a picture of a small burner, with a small skirt which only protects
the flame from wind, not the pot:

http://imageshack.us/photo/my-images/38/rimg1228.jpg/

 

I've searched a bit on Bioenergylist, and in Micro Gasification Cooking with
gas from biomass, I could only find the Vesto stove as a gas stove with a
skirt.

 

This post brings another question, which I will detail in another issue.

 

Thanks in advance,

 

Xavier

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