Re: low power efficiency

["A.D. Karve" <adkarve@pn2.vsnl.net.in>]

Dear Ms Bond,
the discussion so far shows that the boiling and evaporation test that we
have so far been conducting, gives us just that, i.e. efficiency of boiling
and evaporating water. It does not really reflect the cooking efficiency of
a stove, which is operated in many different ways. One of the standard
procedures in cooking anything is to bring the water to a boil, then cover
the pot, reduce the flame and just allow the pot to simmer.  Experience with
solar cookers and also with the hot box show, that one does not even require
a temperature of 100 degrees Celsius for cooking.  With the pot just
simmering, there would be very little evaporation, and, as you have rightly
mentioned, the efficiency of the stove would be near zero, and yet the
cooking process would be completed with very little fuel. Therefore, the
test that has been recommended by the Ministry of Non-Conventional Energy
Sources, Government of India,  requires the tester to keep a series of
standard pots ready, filled with a certain constant amount of water. The pot
is covered with a lid. As soon as water in one pot reaches a certain
temperature, say 90 or 95 degrees, one takes it down and sets the next pot
on the stove.  In this way, only the rise in temperature of the water is
taken into account and not the amount of water evaporated. One has to make
some allowance for the conductivity of the metal of the pot, because heat
would be lost through the surface of the pot.
A.D.Karve
-----Original Message-----
From: Tami Bond <tami.bond@noaa.gov>
To: stoves@crest.org <stoves@crest.org>
Cc: ethos <ethos@vrac.iastate.edu>
Date: Friday, March 08, 2002 3:04 PM
Subject: Re: low power efficiency


>
>Dean,
>
>More technical babbling:
>
>> A great stove would get a higher
>> score because it is most efficiently changing water to steam. Lots of
stoves
>> loose on both scores.
>
>What affects evaporation rate? Only the temperature of the water and the
>removal of the water vapor from the liquid surface, allowing more water
>to boil off. Neither one really has to do with the stove. A great stove
>would get a higher score because it would lose less heat-- which as you
>say is only related to the real service. If you kept the pot simmering
>but evaporated NO water, the user's demand would be met, but the
>(apparent) efficiency would be zero.
>
>It seems to me that overfiring would be the biggest cause of efficiency
>loss. The pot can only absorb so much heat. The rest is lost. What do
>you people with real-world experience think about that? How do you keep
>people from overfiring (other than getting Larry to build you a feed
>magazine?)
>
>> A 3 stone fire can be made very well and can score above 20% (Tami may
hold
>> the world's record for BEST THREE STONE FIRE)
>
>I don't believe my own numbers, there. :-)
>
>Tami
>
>-
>Stoves List Archives and Website:
>http://www.crest.org/discussion/stoves/200202/
>http://crest.org/discussiongroups/resources/stoves/ (Under construction)
>http://www.ikweb.com/enuff/public_html/Stoves.html (Original)
>
>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://www.crest.org/articles/static/1/1010424940_7.html Bioenergy
>http://www.crest.org/articles/static/1/1011975339_7.html Gasification
>http://www.crest.org/articles/static/1/1011975672_7.html Carbon
>
>For information about CHAMBERS STOVES
>http://www.ikweb.com/enuff/public_html/Chamber.htm
>
>


-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/200202/
http://crest.org/discussiongroups/resources/stoves/ (Under construction)
http://www.ikweb.com/enuff/public_html/Stoves.html (Original)

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://www.crest.org/articles/static/1/1010424940_7.html Bioenergy
http://www.crest.org/articles/static/1/1011975339_7.html Gasification
http://www.crest.org/articles/static/1/1011975672_7.html Carbon

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