Lanny and all,
The wood you describe can be called "segments" (in contrast to
"stickwood" of greater and irregular length, or chips /chunks that are
so much shorter).
In Uganda we regularly use wood segments that are 18 - 20 cm (nearly 8
inches) long because that size fits well vertically in the Quad TLUD
stove by Awamu.
No problem with rapid burning when the batch is top-lit. But the
segments should be snugly packed. And in the case of any large
vertical gaps, some chips or even charcoal pieces can be added to the
fuel BEFORE ignition to minimize the difficulty of the fire (embers)
dropping down to the bottom of the batch of fuel.
Also, I have an unsubstantiated hunch (observed but not studied) that
even when the fire moves down one side more than uniformly migrating
downward, the heat of pyrolysis does move laterally (still rather slowly
and with very controlled supply of primary air).
Paul
Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
Email: [email protected]
Skype: paultlud Phone: +1-309-452-7072
Website: www.drtlud.com
On 9/22/2013 8:39 PM, Lanny Henson wrote:
I would like to see wood at least 15 cm/6 inches long being used in
future test.
I noticed the size of the wood In the test is 2 x 2 and 2-7.63 cm
long. That translates to about ¾" x ¾" and ¾" to 3" long, for my
fellow "meterphobics" (unnatural fear of the metric system)
7.63 cm is very small wood and It takes a lot of work to cut wood down
to that size. It is not the diameter that is a problem because wood is
easily split to smaller diameters but the length of ¾' to 3" is a
problem because the cross cut is more difficult.
I have seen comments that users do not like to cut wood down to small
pieces so I wonder how practical a household size stove is going to be
unless it is flexible enough to burn larger size wood.
Even 15 cm may be too short for some end users. If I am wrong about
the small wood problem please let me know.
The problem with designing a batch-fueled stove that will burn 6"
long wood, is that it is more of a challenge than a stove that will
only burn wood 3" long, because the size of the burner needs to be
different. Wood needs to lay horizontally with the grain when being
burned in a batch, because wood does not burn well standing on the
end. It reacts all at once and the burn is not steady and continuous,
like it is when the pieces are laying horizontally. Laying
horizontally and top lit the pieces burn a few at time as the flame
burns down through the fuel bed in more steady way, with less heat
spikes and dips. The taller the stack the better for the same reason.
I am working on a burner that will hold 1Kg of 6" long wood. It is
oval to hold the longer pieces but narrow so the wood will make a
taller stack. It burns the wood from both ends and there is no grate
or even a bottom to the stove. This is very handy for saving the
charcoal, just lift the stove off and lay a cap over the pile of
charcoal on the ground to extinguish it. When I am able to walk again
I will take some photos
Lanny
----- Original Message ----- From: "Jetter, James" <[email protected]>
To: <[email protected]>
Sent: Saturday, September 21, 2013 5:35 PM
Subject: [Stoves] Recorded EPA webinar and files posted
To All,
Thanks to those who joined us for the webinar on August 29, and
thanks to the Global Alliance for Clean Cookstoves for hosting.
The recorded webinar, presentation slides with notes, and draft
spreadsheet have been posted for your information, review, and comments:
http://community.cleancookstoves.org/communities/forums/viewtopic/22/33/207?post_id=357#p357
The purpose of the webinar was to:
Provide an update on the EPA cookstove testing project
Present a format (EPA spreadsheet) for sharing data
Discuss test methods
Focus on example testing results for a batch-fueled pyrolytic TLUD
(top-lit up-draft) stove
Solicit further comments on methods, spreadsheet, and data sharing
Please let me know if you have any further comments by Oct. 11. My
email address is: [email protected]
Regards,
Jim Jetter
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