[Stoves] Understanding Stoves

[Xavier Brandao]

I found the review of the stoves principles by Dr Sai Bhaskar Reddy Nakka
just great. This is what every person beginning with stove design should
read. Because this person will necessarily face one of the problems
described, if not all.

Yes, height is the major concern for institutional stoves, so I discovered
also. I also have been progressively paying attention to the size of the
cooks, the length of their spoon, the height of their small wooden bench,
etc. The size of the earth stoves they use already : 80 cm from the ground
to the top of the pot/surface of the water. Our rocket stove for the same
size of pot was 93 cm to the top of the pot. The women also have trouble
carrying the heavy pot full of water over the tall skirt. They even needed
to put the pot on the skirt (which if fortunately a double-skirt), and then
in the stove. On the contrary, their traditional earth stoves are 50 to 60
cm high. Very practical. Our biggest stove is, or was, 110 cm high!

We decided to reduce the space between the stove and the ground, the space
and insulation under the combustion chamber. We reduced the chamber of
1/5th. Our tests showed similar performances than the normal-sized stove in
terms of time and fuel efficiency. There wasn't more smoke, but we didn't
have the instruments to measure the gas emissions. We managed to reduce size
by about 15 cm, much to do still.
The best technique I saw: the pot is put empty on the stove, filled with a
waterhose, and emptied in small containers on a trolley.
While writing this email, I am thinking: any way to make a removable skirt,
so it is more practical to move the pot in and out of the stove? But then I
am not sure removing the (greasy) skirt is very practical either ...

Regards,

Xavier

-----Message d'origine-----
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Message: 4
Date: Sat, 10 Dec 2011 10:32:05 +0530
From: Sai Bhaskar Reddy Nakka <saibhaskarnakka at gmail.com>
To: stoves at lists.bioenergylists.org
Subject: Re: [Stoves] Understanding Stoves
Message-ID:
	<CAN7CAbXx8uAEjD2ksWob09K5SBSmRe_bkzR8NBgp-qscj0Tn9A at mail.gmail.com>
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Dear Crispin,

Thanks a lot. In the two pot stoves, while the gases move towards the
second pot, there is some length and time for gases for combustion. In the
two pot stoves the draft of the flames is across before reaching the second
pot. Importantly, for the single pot stoves, short chimney is a great idea.
I agree with Dr. Karve the cost of chimney costs more than the stove.

The height of a average Indian women while sitting on the floor and cooking
is about 2 to 2.5 feet (it will be even less when they bend in acute angle
to reach the stove, as they cannot sit too close to the stove). It is
almost inconvenient for them to cook on a stove along with the cooking
vessel which reaches above 1.5 feet.

Similarly for institutional stoves, especially for the cooking needs of 200
for more and served at a time (schools / hotels / etc.) the height of the
stove is a major concern. From the surface of the ground they will never
let the height of the stove exceed 6 inches. I had to literally push the
stove into the ground and create a ramp to meet the needs of the cook.
Because for stirring and lifting the cooked food from fire, etc., are the
difficult tasks. The utensil is usually dragged to the serving area.

Dr. N. Sai Bhaskar Reddy