It does take a long time for dry wood to totally absorb water but 50 min is
not insignificant, and concrete block soaks up water a lot faster. I am
thinking that even the water on the surface of wood or even dry wood is a
problem for most top lit batch burners.
My point is that if you toss something wet or noncombustible in the burner,
it is so forgiving it just burns around it, or actually over the top of it,
and if you are outside cooking in the rain and your you dry wood gets a
little wet that is not a problem for my stove.
I had the camera turned off when the concrete exploded, I wish I had
captured that.
Green wood is a problem, it stinks up the place and smuts the pot but it
will still burn fresh green wood after the fire heats up. Green wood
probably takes away more energy than it provides but it will burn fist size
chunks.
I will weigh the wood before and after soaking next time.
How much moisture content is the break even point?
Lanny
----- Original Message -----
From: <[email protected]>
To: "Discussion of biomass cooking stoves" <[email protected]>
Sent: Saturday, August 10, 2013 11:43 AM
Subject: Re: [Stoves] LannyPan cooking module and the TLC burner
[Default] On Sat, 10 Aug 2013 09:21:36 -0400,"Lanny Henson"
<[email protected]> wrote:
In the video where I am cooking in the rain, I feed in wet wood and wet
concrete block without loosing flaming combustion or creating visible
smoke.
Not wishing to criticise your design,Lanny, as it seems well made and
economical. I do question the way you soak the wood as it is
meaningless unless you establish how much water it has soaked up. Re
wetting logs takes a long time because the surface tension of the
water will not allow re absorption in a short time.
The issue is that boiling water off from a green log is highly
endothermic, the part of the log exposed to the fire cannot ignite
until it starts pyrolysing and this needs a temperature of 230C+. The
moisture content holds the bit of the log to 100C until it is boiled
off and this is what depresses the combustion temperature and prevent
a flame cleanly burning out the Products of Incomplete Combustion,
which then appear as smoke alongside any droplets of water that have
condensed as the flue is cooled.
AJH
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