Re: Temperature dilution

["Paul S. Anderson" <psanders@ilstu.edu>]

At 07:41 AM 5/23/02 -0700, Tom Miles wrote:
>Paul, Andrew
>
>Mixing gases of similar densities requires energy whether it is for primary
>or secondary air. To conserve energy some designs concentrate small jets of
>combustion air impinging on small areas of fuel. Good secondary air mixing
>is also done with jets as Tom demonstrates in the burner "ring" of his
>turbostove. (See photo at
>http://crest.org/discussiongroups/resources/stoves/ ) We sometimes use
>eductor or venturi designs for mixing. These also require energy to
>penetrate and mix with combustible gases. It seems to me that the challenge
>is to "blow on the fire" without using a bellows (external energy). To do
>that you have to have a pressure differential or a temperature differential.
>
>Tom Miles

All,

1.  Tom Reed is already "blowing on the fire" with his small fan in a gasifier.

2.  If the increase in available energy (because of using HOT air) exceeds 
the energy requirement to blow the hot air, then the net gain is to be desired.

3.  If the pre-heating of the air is accomplished by the combustion 
process, is the loss of energy (needed for air pre-heating) significant in 
relation to the gain by using the pre-heated air to obtain better 
combustion (via less temperature dilution)?  Many variables here, including 
the stove structure that pre-heats the air at the chimney-level (considered 
to be mainly wasted heat except for needed draft) versus pre-heating closer 
to the combustion chamber.

4.  I have previously written about the 4 components or issues of stoves 
:  fuel, combustion chamber, physical structure, and the cooking 
practices.  But Tom Reed recently argued to me when we met that a 5th 
component could be "air".  I countered with a comment that "air is air" and 
we assume it is available, and that the issues about air are really within 
the issues of the combustion chamber and how it treats and delivers the 
air.  Air is essential, but I have not yet added it to the list of the 4 
components.  (Your thoughts would be appreciated on this topic.)

ELK,  Are we getting back to our prior levels of communication?

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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