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<DIV><FONT size=2 face=Arial>All,</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>I have just spent 2 1/2 weeks at Aprovecho Wood
S</FONT><FONT size=2 face=Arial>tove Research Center in Oregon. Dean Still
set for me the lofty goal of developing a TLUD-ND which is tier 4 in all
catigories. We probably missed this goal, but we did make
progress. We have a test TLUD-ND which can boil a 5L pot of water in
around 20 minutes, and then turn down and simmer it between the required
test temperatures of 93C and 98C. At one point the water was in
danger of droping below 93C, and the flame had to be turned up, so we also have
some extra turn-down. Additionally, the PM and CO levels were very low at
all power levels for most of the time. One exception was one test where
the CO remained slightly high at low power. The fire was below the wick
(see attachment) and was burning char, creating an excess of CO. We had
the usual increases at the start up and flame out, and also small momentary
increases in both PM and CO during the transition from high to low power
levels. </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>The turn-down method we used is a further
development of the pilot flame method I discussed a couple of years ago on the
list. It now includes what I call a wick, a central disk with radial
slits, attached to the combustor section. It works with the pilot
flames to stablize the low power flame. The method requires only that the
primary air be turned down, which makes it simple to make and use. The
control device has to be very sensitive at the low end since a small change
makes a big difference in the low power flame. Another problem
we encountered was creosote which formed on the interior of the fuel/reaction
chamber wall (see attachment). Burning the char for a minute or two after
flame out cleared this deposit. Insulating the wall may keep it hot
enough that the creosote will not deposit.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>This improving of the pilot flame
turn-down technique would not have been possible without the equipment at
Aprovecho. The real time sensing and computer graphing equipment enabled
us to quickly see the effects of any changes we made. At one point, when
the stove was unstable and could not reach low power, I tried removing the
stationary fan which swirls the high power flame thinking it might be causing a
problem. The stove was then able to reach the low power levels. I
made a small change in the bend of the fan blades to allow more opening between
the blades, put it back into the stove, and the low power flame
remained stable. We now had both clean high power because of the
swirl, and clean low power. The low power flame needed a more open stove
with less flow resistance than the high power flame. This is counter
intuitive at first, but makes sense because the high power flame has more
buoyant force (draft) pushing the flame through the fan. I would not have
found this without Aprovecho's real time readout equipment.</FONT></DIV>
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<DIV>
<P style="MARGIN: 0in 0in 10pt" class=MsoNormal><SPAN
style="LINE-HEIGHT: 115%; FONT-SIZE: 14pt"><FONT face=Arial>I hope to work at
Aprovecho Research Center in the future and I encourage others who are
interested in wood stove research to work at ARC or a similarly equipted
lab. The equipment very much helps with stove experimenting and
designing!</FONT></SPAN></P></DIV>
<DIV><FONT size=2 face=Arial>Kirk</FONT></DIV>
<DIV><FONT size=2 face=Arial>Santa Rosa, CA. USA</FONT></DIV>
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