Re: Juntos (together) stove !!! This works!!

["Ron Larson" <ronallarson@qwest.net>]

Paul:

    Like Tom Reed,  I congratulate you on coming up with your new "juntos"
design reported on 12/31.  Some questions below.  (Like others, I hope for a
diagram when you can get to it.  Maybe my issues will help).

You said:

    <snip>

a.  " I boiled a liter of water in 5 minutes."

    This is indeed a good value - but I can't even remember others.   I
vaguely recall that the Japanese liquid fuel camping stove Physician had
around 3 minutes as his lower limit  (I think also for a liter).  Anyone
able
to beat Paul's number?  I am sure I never did so well.  Was there shielding
around the pot - what size and shape pot?   Can you estimate anything about
the power output (kW) or fuel consumption rate (grams per minute?).

b.  I like your "juntos" name and explanation.  Also "tincanium".  However,
I hope the "minch" will be dropped - even more than I hope we can drop
inches, BTUs, and horsepower on this list.  Metric units need to and can
come to the US - and maybe the stoves list can lead the way.  Every US
stover I know can handle the metric system and usually does.
To the accuracy we achieve on this list, the minch is an inch anyway.

c.  You coupled the terms:  "Fast initial heat, Long-term slow heat"   Can
you (now or later) couple this with an estimate in kW (or grams per minute).
Also helpful would be this only as a (turn-down) ratio.

d.  You said "Projected cost to be under $10 per unit, maybe under $3 if not
counting local labor and materials"
Was this an estimate using cans or starting from scratch?  Village artisans
or factories?  I think it important to emphasize to this list that
controlling air flow does not have to be expensive.  Congratulations

e.  You said:   <snip>
"1.  The lower or bottom unit ...... with plenty of air holes at bottom or
around the lower outside edge."
    (RWL):  Could you better define the number and size of air holes -  Do
you think there might be any advantage to making these secondary air holes
controllable? (So as to control the excess air ratio?)

f.  In (2), you used the terms "basket grate"  and "bucket" which I  like
much better than "grate" as used by Crispin.  Having seen the predecessor
stove in Zimbabwe, I have a clearer picture of this than most - but think we
should use the "bucket grate" term when there are not many holes, and
"basket grate" otherwise..

g.  In (3)  you note that for the basket grate "...only the top quarter has
air holes in the side walls"   I think this is critical and glad to see that
you are planning to test with other configurations of holes.  My work has
never had any holes in the fuel container, and I think the Zimbabwe
equivalent (name forgotten) had holes everywhere (no air control)
My (poor) recollection is that someone 3-4 years ago reported on a "basket
grate" with a top lit, air controlled, updraft charcoal-making,
natural-draft stove (I am intentionally trying to avoid the term IDD). which
had several (many?) holes per square cm ( perforated metal - rather like a
screen).  It surprised me then and still does that this seemed to work.
Anyone on the list remember that stove developer?   I do like this approach
for preheating the secondary air.

h.  In (4)  You introduce the controllable "Anderson air pipe" which I
believe has not been previously reported.  Tom Reed does employ a blower
this way.  Could you describe how you control the primary air - and how you
ensure a tight coupling?

i.  Also in (4) You talk about the ".... gasification (pyrolysis) zone that
is gradually burning downward after being TOP LIGHTED."   I would prefer to
drop the term "gasification" in this mode and say instead " .. the pyrolysis
zone is moving downward".  We often hear of "charcoal burning" - which can
mean two very different things - either consuming or making charcoal (by
pyrolysis, not gasification).  Small point, but I predict some list members
just starting up in later years will go off in the wrong direction with
these uses of "gasification" and "burning".

j.  Re "5.  Enter the Rocket Stove."     I  like this!!      Could you add
more on the nature of the grid (a grate) you have employed?  Any
deterioration?  Will this have to be stainless?  Etc  (We had one report on
using locally made ceramic rods successfully as a grate.)

k.  You said Re  "6. [you] .... could place an additional ring (for more
chimney effect) or place a holder for the pot of water."  Could you clarify
which you did in the test reported - and what the combustion area height was
for the Rocket Stove alone?

l.  Also in (6) you said:  "... the heat generation containers would NOT be
required to support the weight of the cooking pots.  And therefore the heat
generation containers can be inserted and removed from the area (a chamber?)
that is below the cooking spot."   I think this is a very important point
that we need to discuss more.  The alterative is too often quite tippy, and
as you say not amenable to change-out.  In Ethiopia, I tried a tripod
arrangement for the burner surface support - with mixed results.  (hard to
get level)

m.  Re (7). "....:  I rigged up a bicycle tire pump..."   Anything to report
(beyond that below)?  Is "puffiness" a problem?  Would a homeowner be
willing to do?

n.  Re (9a) , you said:   " By itself, the lower unit (the gasifier) .....
Not much draft.   Languishing flames."  (Again - I would prefer "pyrolyzer"
over "gasifier")    Was there any combustion chamber height (to attain a
better draft) above the lower pyrolyzing chamber?  I am surprised that it
worked at all, if there was no upper cylinder.  What was the depth of the
fuel below the uppermost lip surface in this test?

o.  Re (9d) You said:  "  The flames above must have been pulling in a draft
of primary air.  I only played a little with trying to limit the primary air
via the air-pipe."   Others who have not tried this will not appreciate the
"tremendous" (loosely speaking) draft available from chimney heights even as
little as 15 cm.  Some control mechanisms I have tried, that looked visually
like they were tightly closed, still let in too much primary air.  Again, I
am interested in how you were controlling the primary air through the tube
(rotating valves, flaps, plugs, etc)

p   Re (9e).  You said:   ".... Then the gasifier continued to put out nice
moderate heat that could keep a slow boil going."  I think the added fuel
input port above (part of the bottomless "Rocket") has many nice potential
features - but I worry about not being able to control its air flow.  Maybe
you can see a way to put a closeable door there - to keep the excess air
ratio down - and keep efficiencies up.

q.  re (9f)  You said:  ."....  To consume in the stove or remove the
charcoal is an open option."   Did you mean this last sentence to apply in
all cases or in only the case with the "forge" operation obtainable with the
air pump?  I wonder if Dan Diminiuk or Das or other stove-list metal working
experts could say something about the modern blacksmith's use of a forge air
blower that has a large enough angular momentum to keep rotating and pumping
air for a minute or so (a guess) before being cranked up again.  Can these
be produced at sufficiently low cost to be used to help consume the
charcoal?  Should we stick with electrically powered blowers?

Re  your "10.  Discussion"   No comments nor questions.  We will all benefit
from diagrams, but your description was excellent.  Hope my questions might
spark some discussion (and further experiments) of the type you:are urging.

    Your "togetherness" approach is also reminiscent of the "Dasifier"
developed by our new "stoves" member Das (and introduced by Tom Reed on Nov.
5).  Das also was coupling two very different (in his case, UD and DD)
approaches in a single device - with nice consequences.

    Your submission has also asked me to ask myself whether the proposed DD
pyrolysis stove of the type I described on 27 December  (that I still think
has not been constructed) has a parallel along the lines you are
investigating.  That is - what does a "DD Rocket" look like and does it
operate with the advantages you have given?  Tis late, so I'll see if I have
an answer after sleeping on it.  Offhand, your combined UD approach looks
much better (ability to add fuel late in the process, get higher output
power (turn-up ratio) when starting or otherwise needed).  The main
advantage of the DD pyrolyzer stove concept is that the required draft gets
all emissions out of the room - so maybe the added feature of another
down-stream fuel port may also be worth considering.

    Anyone else have a comparable "juntos" ("together") stove idea?

    Lastly, Paul - any negatives that you have thought of?  Would you guess
that the extra cost of combining types will generally be found valuable
for/by users?  Any concerns about being able to teach users?

    Again, thanks for providing this early report.  I look forward to
hearing more - especially on your results with different types of fuels.  It
is great to hear that the juntos is so tolerant of fuel type.   It will be
interesting to see the juntos subjected to laboratory-type emissions and
efficiency testing.  Maybe with support from the Shell Foundation.

Ron









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