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<DIV><FONT size=2 face=Arial>Manqolazi,<BR></FONT></DIV>
<DIV><FONT size=2 face=Arial>Thank you for your interest.<BR></FONT></DIV>
<DIV><FONT size=2 face=Arial>Hi, that's a great design. I'm a complete stove
newbie so I hope you don't mind my basic questions. </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>I have named the stove the Wonderwerk stove
after a cave in South Africa which is an archeological site where signs of
controlled fire use by early humans is being found. I have named the
combustor (the section that sits on top of the stove and is removable for
fueling) the Strata combustor because in a site like Wonderwerk Cave the layers
laid down over time are called strata, and this combustor has a number of
layers. </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Is the fan shaped piece of metal for more complete
combustion? What effect does it have on the flame at low vs high power?
<BR></FONT></DIV>
<DIV><FONT size=2 face=Arial>The lowest combustor layer is the spider like thing
that hangs under the combustor between the legs. It is not a fan though
there is a stationary fan in a higher up layer. It has two purposes:
to enable turn-down to quite a low power level, and to help clean the high power
flame. <BR></FONT></DIV>
<DIV><FONT size=2 face=Arial>Turn-down: The full explanation is quite
long. The short version is that it keeps the secondary air from falling
into the fuel chamber, diluting the wood gas and putting the flame out.
Also it gives a stable location for the medium and high power flame to
sit.<BR></FONT></DIV>
<DIV><FONT size=2 face=Arial>High power: It divides the wood gas into
sheets (18 sheets in this version). Think of the gas as being extruded
through the slits. Because of the radial arrangement of the sheets, air
can move inward between the sheets of gas and feed the sheets from both
sides. Thus no portion of wood gas is more than 3 mm from a source of
secondary air. There is no column of unmixed gas going up the middle as in
many TLUD-ND stoves. This gives good mixing and good
combustion.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Do you get a lot of soot on the bottom of the pot?
<BR></FONT></DIV>
<DIV><FONT size=2 face=Arial>There is very very little soot on the pot, mostly
if I make a mistake operating the stove. There needs to be some soot or
other black coating on the pot to absorb radiant energy. A clean metallic
pot will reflect radiant energy and so lose some heat. This can be a
problem with this stove if there is not enough soot to coat the pot to absorb
radiant energy.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Does all the secondary air come in from the bottom
of the reactor module or does the combustor also have secondary inlets?
<BR></FONT></DIV>
<DIV><FONT size=2 face=Arial>Secondary air enters from three locations:
<BR>1. The pilot holes just below the top of the chamber. These help
give turn-down by injecting a small amount of air before the reduced and lower
temperature wood gas is diluted by the not reduced secondary air (at lower
power levels the excess secondary air will further cool the already low
temperature wood gas to below combustion temperatures, putting the flame
out. Also it dilutes the wood gas making it to lean to burn. That is
why TLUDs are difficult to turn down). The pilot flames keep flame
presence (I learned this from Dr. Anderson) and heat and ignite the remaining
wood gas as it mixes with the secondary air.<BR>2. Secondary air enters
over the top edge of the chamber. Many stoves use an array of holes around
the perimeter rather than allowing the secondary air to spill over the top
edge.<BR>3. The next layer up in the combustor is an array of tubes with
slits in the sides that feeds air into the flame to make sure that every bit of
wood gas has access to oxygen to burn.<BR></FONT></DIV>
<DIV><FONT size=2 face=Arial>These secondary air entrances, working together
give a thorough mixing of wood gas and air for clean combustion.
<BR></FONT></DIV>
<DIV><FONT size=2 face=Arial>The next layer up is the stationary fan which spins
the flame. This makes the flame take and angled path which is longer than
straight up, and so gives the flame more time to finish burning before it gives
up its heat to the cooking surface. Also spinning the flame compacts it,
keeping it hotter.</DIV></FONT>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>The several layers, if not properly designed, can
add considerable resistance to the gas flow through the stove. This can
hinder the achievable high and low power levels. Properly designed the
flow remains strong and both the high and low power levels work well. The
low power flame needs a more open stove with less resistance than the high power
flame.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Thanks and cheers!<BR></FONT></DIV>
<DIV><FONT size=2 face=Arial>I hope this answers your
questions.<BR></FONT></DIV>
<DIV><FONT size=2 face=Arial>Kirk<BR></DIV></FONT>
<DIV><FONT size=2 face=Arial>----- Original Message ----- </FONT>
<DIV><FONT size=2 face=Arial>From: "Mangolazi" <</FONT><A
href="mailto:mangolazi@yahoo.com"><FONT size=2
face=Arial>mangolazi@yahoo.com</FONT></A><FONT size=2
face=Arial>></FONT></DIV>
<DIV><FONT size=2 face=Arial>To: "Discussion of biomass cooking stoves"
<</FONT><A href="mailto:stoves@lists.bioenergylists.org"><FONT size=2
face=Arial>stoves@lists.bioenergylists.org</FONT></A><FONT size=2
face=Arial>></FONT></DIV>
<DIV><FONT size=2 face=Arial>Sent: Tuesday, May 31, 2016 1:38 AM</FONT></DIV>
<DIV><FONT size=2 face=Arial>Subject: Re: [Stoves] stove test</FONT></DIV></DIV>
<DIV><FONT face=Arial><BR><FONT size=2></FONT></FONT></DIV><FONT size=2
face=Arial>> Hi, that's a great design. I'm a complete stove newbie so I hope
you don't mind my basic questions. <BR>> <BR>> Is the fan shaped piece of
metal for more complete combustion? What effect does it have on the flame at low
vs high power? <BR>> <BR>> Do you get a lot of soot on the bottom of the
pot? <BR>> <BR>> Does all the secondary air come in from the bottom of the
reactor module or does the combustor also have secondary inlets? <BR>>
<BR>> Thanks and cheers! <BR>> <BR>> On May 30, 2016 7:56:15 AM
GMT+08:00, kgharris <</FONT><A href="mailto:kgharris@sonic.net"><FONT size=2
face=Arial>kgharris@sonic.net</FONT></A><FONT size=2 face=Arial>>
wrote:<BR>>>All,<BR>>><BR>>> <BR>>><BR>>>The
TLUD-ND stove which we further developed at Aprovecho Research<BR>>>Center
in<BR>>>March was tested at the Lawrence Berkley Lab. Results are
attached. <BR>>>The<BR>>>photo of the computer screen showing the
full power 6+kw graphs was<BR>>>taken by<BR>>>Ashok Gadgil.
They have a good team doing the tests.<BR>>><BR>>>
<BR>>><BR>>>The stove is in route to Aprovecho RC where it will be
photographed and<BR>>>drawings will be made. Apro will then update
their free online tier 4<BR>>>stove<BR>>>book from the old TLUD-ND
design to include this new design. I am<BR>>>updating<BR>>>the
written stove description.<BR>>><BR>>> <BR>>><BR>>>The
designs are being put into the public domain. I hope that
the<BR>>>various<BR>>>principles used in the stove, for turn-down
and improved efficiency and<BR>>>emissions, will benefit some new stove
designs in the future. <BR>>><BR>>>
<BR>>><BR>>>The fuel used was Douglas fir pellets. The highest
power achieved was<BR>>>6+ kw<BR>>>with some cushion above
that. The low power is 1.6 kw with
some<BR>>>cushion<BR>>>below that. The turn-down is then 4 to
1. Five kw seems to be the<BR>>>highest<BR>>>very clean power
level. The high power used in the tests was
around<BR>>>3.25<BR>>>kw. At these turn-down levels the
ambient room temperature makes a big<BR>>>difference in performance.
At 24C room temperature there was no<BR>>>problem<BR>>>keeping the
water in the 93C to 97C test simmering range. At 30C
room<BR>>>temperature the simmering water temperature could not be held
below<BR>>>97C.<BR>>>The pot skirt had to be raised to release some
heat to maintain the<BR>>>test<BR>>>temperature. This is
possibly what lead to the tier 3 rating for
low<BR>>>power<BR>>>specific consumption. The catch 22 is that
the more efficiently heat<BR>>>is<BR>>>given to the pot, the lower
the stove has to be turned down to
maintain<BR>>>a<BR>>>simmer. <BR>>><BR>>>
<BR>>><BR>>>Kirk<BR>>><BR>>>
<BR>>><BR>>>Santa Rosa, CA.
USA<BR>>><BR>>><BR>>><BR>>>------------------------------------------------------------------------<BR>>><BR>>>_______________________________________________<BR>>>Stoves
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web<BR>>>site:<BR>>>http://stoves.bioenergylists.org/<BR>>
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