Lanny's Rocket Wok Cooking Stove

["Dean Still" <dstill@epud.net>]

Dear Friends,

I received Lanny's beautifully made stainless steel stove a couple of weeks
ago and have really enjoyed playing with it. The stove features a ceramic
well insulated Rocket combustion chamber with a eight inch tall internal
chimney below the partially sunken wok (three inches below the top of the
stove). A horizontal twelve inch long, five inch in diameter tube makes the
feed magazine and connects to the bottom of the internal chimney below the
wok. The wok seals at a circular rim so flue gases exit from a six inch in
diameter stove pipe installed in the side of the stove body. If the stove is
lit without troubles no smoke enters the room since the seal is well made. A
shelf, one third up from the bottom the tube, holds seven one inch in
diameter sticks that are pushed into the fire as they are burnt. Air enters
under the shelf, especially when sticks fill the space on top.

First, a couple of remarks about the wok as a great example of evolution in
cooking design. Folks at Aprovecho hate one thing most about using wood for
cooking, soot on the pots make them impossible to clean in a sink without
sooting up the sink, hands, towels, etc. So staff have forced the A.T.
builders to make griddle stoves where soot does not touch pots. But, as we
all know, passing heat through steel into pots is not a most efficient use
of wood. (As a rule of thumb, the griddle halves efficiency.)

The wok solves this problem because it is cleaned in place using a brush and
water available at the stove. The waste water is dumped onto the inclined
top of the stove and drains into a trough that funnels waste down a tube.
The soot does not contaminate the cleanliness of the kitchen. Marvelous
idea! Also the wok can be used for boiling, steaming and frying, even
baking. The steel is thin for good heat transfer and the bowl shape is also
helpful in this regard. Tools to make use of the wok have evolved over time
and are equally ingenious. And cheap because so many are made. Woks are a
great reminder to me that looking for human evolved answers to A.T. problems
is probably a lot more effective than other more removed approaches; i.e.,
white guys like me who haven't cooked much with wood coming up with
"inventions".

The 150,000,000 improved wok stoves recently made in China use a box like
combustion chamber under the wok formed from cast iron surrounded by
insulation. I wondered if a Rocket combustion chamber might help the stove
to be a bit more fuel efficient and less polluting. So Lanny and I worked up
a prototype that I'm now testing and tweaking.

Today, I put about 11 pounds of water, (5,000 grams), in the wok. The water
was brought to a rolling boil in 11 minutes. I then kept the water close to
212F (100C) for 1/2 an hour and used 960 grams of wood. Two to three sticks
were needed to keep the water at temperature. I use 8,600 BTU's per pound of
wood. Adding up sensible heat and figuring 1,005 BTU per pound of water
boiled off, the stove was 28% fuel efficient. My son and a friend need a
school project and we will work together to improve the heat transfer by
finding the best gap between the wok and the skirt that forces hot flue
gases to scrape against the wok surface under the stove top. We also will
try reducing the one inch distance between the top of the internal chimney
and the bottom of the wok. Having a external chimney (6' high in the
experimental model) gives us a lot of draft allowing gaps to shrink.

After we get done, the stove goes to a family of 6 who will use the stove
for a month and report back. I'll put a picture on the ETHOS page when it's
up and write again if we improve efficiency. So far my only major
improvement would be to try lowering more of the wok under the top of the
stove. A six inch feed magazine would give more power but I'm going to wait
and see if the family thinks it necessary.

Best,

Dean




-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/current/
http://www.ikweb.com/enuff/public_html/Stoves.html

Stoves List Moderators:
Ron Larson, ronallarson@qwest.net
Alex English, english@adan.kingston.net
Elsen L. Karstad, elk@wananchi.com www.chardust.com

List-Post: <mailto:stoves@crest.org>
List-Help: <mailto:stoves-help@crest.org>
List-Unsubscribe: <mailto:stoves-unsubscribe@crest.org>
List-Subscribe: <mailto:stoves-subscribe@crest.org>

Sponsor the Stoves List: http://www.crest.org/discuss3.html
-
Other Biomass Stoves Events and Information:
http://www.bioenergy2002.org
http://solstice.crest.org/renewables/biomass-info/
http://solstice.crest.org/renewables/biomass-info/carbon.shtml

For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm