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Peter (cc stoves):
Yours is a nice looking
unit - I only vaguely remember seeing it earlier (which is dated Feb. 7,
1999). The design is somewhat similar to what I described in my
following note of yesterday - but I like better your lower placement of the
fuel-air sources.
A few questions -
1. Can
you expand on the use of "cheat holes in the riser pipe". I can't spy
them. How large? How far up? How does their existence help
start the updraft mode?
2. Can
you tell us more about the "slide to adjust the active grate area."
Does this change the amount of air flow? I can't figure out the
location. Is it right below the visible grate - or further down? How
far down? What range of areas are possible?
3. What
is the mechanism for removing ash?
4. In
the Khan paper, wood blocks were added at rates like two small blocks every
thirty seconds. What is your typical fuel feed rate?
Have you calculated maximum and minimum power
levels in kW? Is there a "sweet spot"? Have you ever
measured CO or other emissions?
5. Is
there any insulation? (all metal?) Any estimate of
efficiency?
6.
In the US, our barbecues are always (? - at least usually) open grates - not
solid plates like yours (which is of course needed to maintain draft). Is
it typical in other locations where you have lived to have barbecues with solid
surfaces?
7. I
can see using your design as a "griddle", but also as a "plancha-type" - with
ordinary cook pots and a maximum temperature need only of that for boiling
water. Do you have any experience or data on how the stove works that
way?
8.
How uniform is the temperature on the cooking surface? Did you ever
(or could you) try putting a large square basting pan on the cook surface and
observe where boiling is occurring? I'd like to know the max "Figure of
Merit" (ratio of weight of water evaporated to the weight of fuel) you could
obtain (and whether this changes much with the vigor of the boil).
9. The
plate thickness of 10 mm seems a bit large. Any particular reason for that
thickness? How about side thicknesses?
10. I am wondering about your statement that it takes about 12 minutes to
settle down. What is happening during this period? Are you
building up a layer of charcoal below the grate?
11. It
looks like your design could be readily modified to achieve power control
through air flow rather than fuel metering (which offers also the possibility of
charcoal-making). Have you ever seen such a design - and can you supply
references? Does your own work at Eindhoven exist on the web
anywhere? Published in a journal anywhere?
Again my apologies for having not remembered your
prior positive statements about your down-draft barbecue. Besides the
major advantage of getting the smoke out of one's eyes - are there any other
benefits or disadvantages we should know about?
Thanks in advance -
Ron
----- Original Message -----
Sent: Friday, December 28, 2001 4:03
AM
Subject: Re: Continuing on stove
nomenclature and descriptions (Faemus??)
At 17:13 27/12/01 -0700, you wrote:
Alex English message from Dec. 13 on the term IDD encouraged me to make a
stab at stove classification. Perhaps like Alex, I have never taken to
the term IDD because I have never seen a successful down-draft stove
described anywhere and because what Tom and I have been working on is unlike
the unsuccessful down-draft stoves.
I believe I have
and use a succesful downdraft stove, a barbecue. A description and photographs
I sent to Alex quite a few years ago.
The barbecue is still in use and
performs to my great satisfaction. You could say it is continuously fed, in
practice at short intervals, with one to three pieces of wood at a time. It
works on natural draft by way of a chimney and produces no smoke or smell,
which I interpret as clean combustion.
Of course, it doesn't make charcoal,
only ash.
With the very best wishes for a good and happy New
Year.
Piet
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