Dear Paul
(comments below...)
----- Original Message -----
From: Paul Anderson
To: Discussion of biomass cooking stoves
Cc: jetter jim
Sent: Tuesday, April 23, 2013 4:11 PM
Subject: Re: [Stoves] FW: REQUEST for complete sets of raw data of cookstove
tests.
Ron, Crispin, Jim and all,
One stumbling point is the difference between the words Fuel and
Energy. We cook with fuels. We cook with energy. But a piece (1 kg) of
wood (fuel) can deliver 16 MJ of energy if burned to ash or it can deliver
(example) 11 MJ of energy PLUS charcoal that represents 5 MJ of energy.
The piece of wood is totally changed in both cases. But in the second case,
part of that wood has been transformed into charcoal, which is certainly not
wood. Wood consumed is 1 kg. Energy consumed is 11 MJ (with charcoal left
over). Two very different results to be reported.
And then there is the case of one kg of agricultural "refuse" that is 16 MJ
if consumed totally, or 11 MJ plus charcoal if pyrolyzed, and in NEITHER case
was there any consumption of wood. Where deforestation is an issue, stoves
that can use (easily use) agricultural refuse need to be distinguished from the
wood burners.
# To view the issue differently...
Two stoves are being compared for "Efficiency".
Given facts from Tests:
STOVE A STOVE B STOVE C STOVE D
Nature of Fuel Ag. Waste Ag.Waste Stickwood Stickwood
Fuel Energy Supplied, MJ 10 15 10 15
Energy to Cooking Pot, MJ 5 5 5 5
Energy in Char, MJ 0 5 0 5
Stove Efficiency, % 50.00% 33.33% 50.00% 33.33%
# So, we see that for the same cooking task, Stove A and stove C have the
best efficiency, both at 50%
while Stoves B and D also have the same efficiency, both at 33.33%
# Now it is up to the Customer:
IF HE WANTS CHAR, he chooses Stove B if he has Ag Waste for fuel, or stove D,
if he has stickwood fuel
IF HE DOES NOT WANT CHAR, he chooses Stove A if he has Ag Waste for fuel, or
stove C, if he has stickwood fuel.
# Thats all the Customer needs to know, in order to make the best choice of
stove for his circumstances.
Even when the stove testing is conducted with wood as the standard fuel, the
test RESULTS need to clearly reveal that wood did NOT need to be burned.
# This is an efficiency test. This is not a test of the merits of using Ag.
Waste or Stickwood. The test tests teh stove with whatever fuel is supplied.
In the movies, "No animals were harmed in the production of this film."
For SOME cookstoves, "No wood was burned in the cooking of these meals (or
the conducting of these tests)."
# That is an issue above and beyond Stove Efficiency Testing.
What happens to the charcoal (whether burned or as biochar or otherwise lost)
should not be the issue.
# The "Efficiency Test" is a measure of "efficiency of utilization of fuel by
the device being tested." Regardless of the value of the char production, the
simple fact is that the char represents non-utilization of the fuel supplied to
the device being tested. The fact that the char could be used in another stove,
or could be used as Biochar for soil Application is another issue entirely. If
we take credit for the fact that the char could be used elsewhere in another
system, we could really confuse the issue if we claim such things as :
" 20% of the supplied energy was lost through the sidewalls of the stove but
it heated the kitchen beneficially, so I think the Stove Efficiency should be
increased by 20%
or
" I am using the stove to heat a small enclosed greenhouse, and I am venting
the stack gases inside to use the CO2 by the plants. Since the fuel contained
50% carbon, and it was burned to completion, I claim 100% 'Efficiency of
utilization of the fuel."
# External, or "subsequent usage benefits" are issues outside the scope of
"efficiency of use of fuel by the device being tested.
Best wishes,
Kevin
Paul
Paul S. Anderson, PhD aka "Dr TLUD"
Email: [email protected] Skype: paultlud Phone: +1-309-452-7072
Website: www.drtlud.comOn 4/22/2013 6:13 PM, [email protected] wrote:
Crispin, Jim, and List
See few comments below
----------------------------------------------------------------------------
From:
To: "Discussion of biomass cooking stoves" <[email protected]>
Sent: Monday, April 22, 2013 8:47:51 AM
Subject: Re: [Stoves] FW: REQUEST for complete sets of raw data of
cookstove tests.
Dear Jim and Anyone watching
I won't have time to dig through the messages on this thread that were in
limbo. If something is really important to someone, ask again.
With regard to the char remaining and the wood that has been burned on one
end (fuel left over from tests) Harold Annegarn and I have a proposal for how
to deal with stoves that can use fuel remaining from a previous burn. In
principle, the test should be started with the fuel left over from a previous
test. In other words a cooking task that is replicated a number of times in
which the fuel left over goes into the stove for the subsequent task provides
an opportunity to measure (quite accurately) the raw fuel drawn from the pile.
[RWL1: I suggest that any test has to account for stoves being
used to BOTH cook AND make char. I don't sense you will concur with this
variation. Or can you?
I believe that forcing the reuse of char in many/most char-making
stoves will not be the way the char will normally be used - and therefore will
give erroneous results.
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