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<DIV><FONT face=Arial>Hi Steve / Crispin / Roger of Fireside</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>I'm another of these guys who just hasn't got the tech.
language or knowledge so I rely on our experts here and I just try to understand
and comprehend.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Looking at Crispin's and Steve's posts about 4 hours apart
addressing just about the same topic explaining to Roger the ins and outs of
...... call it energy efficiency / need/ release...... I can understand that
Roger is getting confused watching this group.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>I see 2 explanations using different methods and by having
to make assumptions I accept that the results may vary to a certain degree. But
Steve, to say that 5 lb "just about" are 2 kg (it's actually "about" 2.27 which
is a 10 % difference which is when multiplied up ALOT).</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>I really haven't got the time to do alot copy and pasting
here but you both use different base figures to calculate the same thing and OF
COURSE end up with totally different results:</FONT></DIV>
<DIV><FONT face=Arial>Crispin 2.68 hrs at 100 % efficiency</FONT></DIV>
<DIV><FONT face=Arial>Steve 1.6 hrs (efficiency not declared)</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Confusing? Of course. And maybe we see now 2 days spent
analysing why there is that difference. Maybe THAT's what Roger means when he
says lets just get on with doing things. I agree. BUT also let's try to get the
science to a level where we see the same results from different people - because
if we can't get TAHT right how are we expecting to be taken seriously from
either newcomers to the group or the "world at large" when we go out there and
lobby for these 1 billion stoves (or, like some of us, actually trying to get
them where they belong)?</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>OK, off the box - gotta get out there to these people here
in sunny/rainy Gambia and try to explain to THEM why and how it all works......
wished I could be clearer in MY head!</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Cheers</FONT></DIV>
<DIV><FONT face=Arial>George from the ever depleting jungle!</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=steve@thetaylorfamily.org.uk
href="mailto:steve@thetaylorfamily.org.uk">Steve Taylor</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=stoves@lists.bioenergylists.org
href="mailto:stoves@lists.bioenergylists.org">Discussion of biomass cooking
stoves</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, July 27, 2011 8:19
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Stoves] WorldStove replies
to BioFuelWatyche's latestimprecisereporting of facts.</DIV>
<DIV><BR></DIV>Roger. <BR><BR>Here's the maths as I see it.<BR><BR>There is an
accepted amount of energy you can extract from a piece of wood. The very best
case is a piece of oven dried wood, burning in pure oxygen - which is
unrealistic, so from this site <A
href="http://www.woodgas.com/fuel_densities.htm">http://www.woodgas.com/fuel_densities.htm</A>
I can get a value which I am going to call 15 MegaJoules per kilogram. A joule
is the SI unit of energy. 4.2 Joules heats one gram of water one degree
centigrade. We use SI units in here, because it makes the math easier for
everyone.<BR><BR>The group will argue with my choice of 15MJ, but we accept it
isn't 10 x smaller or larger than the "right" value. <BR><BR>A 5 lb log is,
near as damn it for the purposes of illustration, 2kg in SI. That means it
contains 2 x 15,000,000 Joules of releasable energy, 30 MegaJoules (MJ)
<BR><BR>Now, a rate of releasing energy, in Joules/second is called a
Watt. 1 Joule/second = 1 Watt.<BR><BR>5kW = 5000 J/Sec <BR>To release 5kW, we
have to release 5000 joules per second. <BR><BR>You have 30,000,000 Joules in
your log. Burning at 5000 J/s, it can do that for 30,000,000/5000 seconds.
That's 6000 seconds, or 6000/3600 = 1.6 hours. <BR><BR>So all things begin
equal, and Ron says you are claiming a burn-time of 12 hours, you are
releasing energy at 30,000,000 / 3600 / 12....or 700
W<BR><BR>Steve<BR><BR> <BR>
<P>
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