Re: Temperature dilution

["richard stanley" <legacyfound@hotmail.com>]

Paul / Tom,

If you want to see the effect of a fan on the holey briquette without the 
fan,  stack about five of them (the briquettes, not the fans)directly atop 
each other and , leaving a 2 cm gap for air flow through the bottom, ignite 
them at night. You'll soon see a white / blue jet  flame up to 15 cm height 
shooting out the top of the center hole. Color varies according to blend of 
agroresidues used in the briquette) Not that many cook at night but its 
great for a demonstration during a field training exercise. Cannot equal it 
without a stove using wood or charcoal.
Speaking of I ran across the "PEK o PE" biomass gassifier stove in a forest 
training college in rural Uganda a few days ago. I have a nice Jpeg photo 
and  will post as soon as I get home to Ashland from Uganda --in another 
three days. Wasn't this stove introduced through / discussed by / one or 
more of the stovers sometime a while back ?

Richard Stanley
Legacyfound




>From: "Paul S. Anderson" <psanders@ilstu.edu>
>To: AJH <andrew.heggie@dtn.ntl.com>, stoves@crest.org
>Subject: Re: Temperature dilution
>Date: Thu, 30 May 2002 17:36:41 -0500
>
>Andrew and all,
>
>
>>Paul wrote:
>> >My original statement or implied question (above) is related to the 
>>GREAT
>> >difference between the tiny bit of energy needed to do the blowing and 
>>the
>> >(we hope) increase in energy from better burning of the biomass.
>
>>At 08:01 PM 5/30/02 +0100, AJH wrote in reply:
>>The "Natural Draughters" would say they can burn well enough for a
>>"GREAT" difference not to occur.
>Paul now writes:
>I hope we can hear from the "Natural Draughters" about this.
>By the way, among the GASIFER people, I am primarily a "Natural" and Tom
>Reed is focused on the "Force Draft" side of stoves for domestic cooking.
>
>But concerning the small gasifier stoves that Tom and I are developing, the
>impact of the Forced (fanned) air is GREAT, and the energy input to the fan
>is very little.  (more below on this topic.)
>
>>Paul wrote in the earlier message:
>> >An extreme case would be to have a US$ 2 small fan with many months or
>> >years of useful life and a 12-volt battery that is occasionally 
>>recharged,
>> >which together make it possible to burn (in a gasifier or in some other
>> >stove) some form of biomass that is otherwise literally waste product to 
>>be
>> >thrown away.  The heat is from the biomass.  We are just trying to make 
>>it
>> >possible to burn the biomass by providing a small fan.
>>
>>Paul, I am entirely in agreement with you on this, however the USD2
>>fan may not be readily available, the battery has a finite number of
>>charge cycles and the recharging system is not trivial. In fact the
>>*cost* of battery provisioned electricity can be phenomenal. So how
>>would you measure the utility of this motive power and the full cost
>>of getting it? Would a third world cookstove client be prepared to pay
>>a dollar sum for the powered air supply? Would the client be happier
>>forgoing the portion of fuel to raise 70g of steam per hour to do the
>>same job?
>
>Paul now adds:
>I, too, had great doubts about the cost of the battery and fan.  However,
>on my last trip to South Africa (March) I learned more about major SA
>projects (plural) to have "off grid" energy (of the 12 volt DC type from
>solar PV) to something like 50,000 households in each project.  With that
>kind of investment in infrastructure for DC light bulbs and radios, etc.,
>then there is some DC power in place for a fan in a stove.
>
>South Africa is considered an "Economy in Transition" country, and it is
>moving toward Developed World status and structure, and is not slipping
>back toward Third World conditions.  That means that SA does have the
>desire and ability to get the small fans and DC power to significant
>numbers of people who do or will have the financial ability to purchase
>improved stoves (maybe gasifier stoves, maybe other stoves).  (more below)
>
>>Andrew wrote:
>>I find it interesting that both Dean and Rogerio are now tending
>>toward flued cookers. To my mind this makes the combustion easier to
>>control and accommodate. Also the mild induced draught available from
>>a chimney makes the devices inherently safer in keeping combustion
>>products out of the room.
>
>Paul adds:
>Contrast the above thoughts with a (possible) alternative that is a
>force-draft gasifier that burns quite cleanly, might incorporate a small
>hood with vent pipe (but not a flue or chimney), and yields charcoal as a
>useful by-product.
>
>The stove-USERS will be the final decision makers about what stoves they
>will accept (assuming they are offered a choice).  And several designs of
>improved stoves might become quite successful.
>
>>Were Tami's chinese coal fired cookers to
>>move toward the stoves Dean is now promulgating then I am sure we can
>>clean up cooking with coal. Similarly it would allow a modification of
>>the rocket geometry to mitigate the need for fuel metering by pushing
>>the sticks forward, reducing the need to constantly tend the fire.
>
>I look forward to hearing more about these possible variations and 
>improvement.
>
>Thank you, Andrew, for your knowledgeable observations.
>
>Paul
>Paul S. Anderson, Ph.D.,  Fulbright Prof. to Mozambique 8/99 - 7/00
>Rotary University Teacher Grantee to Mozambique >10 mo of 2001-2003
>Dept of Geography - Geology (Box 4400), Illinois State University
>Normal, IL  61790-4400   Voice:  309-438-7360;  FAX:  309-438-5310
>E-mail: psanders@ilstu.edu - Internet items: www.ilstu.edu/~psanders
>
>
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