African Stove tests...

[Reedtb2@cs.com]

Dear Crispin and Paul:

Great news all around.  Good to find out what doesn't work as well as what 
works so negative results are almost as good as positive.  

Your 12 to 15 g/min burn could generate (15 X 18 KJ/g)  270 kJ.  The heat of 
vaporization of water is about 2.4 kJ/g, so 100% efficiency would boil 110 
g/min.  So I agree the 100 g or cc/min is unexpectedly high.

What is the precision of your digital scale?  Mine is 5 g, and I occasionally 
interpolate when the numbers flash back and fourth to 2 g.  I have been 
recommending such a scale for 5 years here at STOVES and as far as I know you 
are the first to use one.  Qualitative is nice, but quantitative is 
eventually necessary.  
                                            oooo
I am here in Southboro MA for Xmas with a laptop with a few keys missing 
(#six, delete, home etc.)  Thinking of taking it apart. Comments?

I have been testing our latest camp stove on twigs and THEY WON'T LIGHT.  Too 
wet?  Too cold here (0 C)?  Too porous so too much underfire air?  Burns fine 
with chips and pellets, but as you say they aren't available everywhere.

TINDER is an important part of all wood burning and especially for top 
lighting.  I use small chips soaked in any alcohol and can start cooking in 
less than a minute on the initially blue flame.  Soaking in any other 
combustible liquid (kerosene, diesel, bacon fat, wax) will work too, but 
makes more soot if clean pots is your object.  Punky wood, pine needles, 
twigs come in a distant third.  

The pace is quickening.  I hope many stoves will be invented and distributed 
in 2002.

Onward to the Ultimate...

TOM REED                  THE BEF STOVEWORKS
<< 
 Dear Stovers
 
 Paul Anderson has once again managed to catch a plane out of South Africa
 and is headed to the US of A with a production prototype stove for Tom Reed
 in tow.
 
 We worked in rushed conditions yesterday briefly burning three fuel types in
 two stoves and I will post the results of that work asap.
 
 He left me with an IDD stove of his own fabrication, some pelletized wood
 and some more Moçambique Briquettes from various materials.
 
 We had the briquette maker (man) with us from Maputo and he seemed very
 impressed with the way the Basintuthu burned his briquettes (broken up to
 suit the fire grate).  He was able to see the stove working but not inspect
 it's innards.  It has preheated primary and secondary air.
 
 I can report that the charcoaling gassifier was consuming 4 grames of fuel
 per minute (net) and the Moç sawdust-charcoal-paper briquettes had an
 identical burn rate in the Basintuthu Single Stove which was too slow for
 our needs.  The square New Dawn paper-sawdust briquettes, with no holes in
 them for a change, burned up to 24 grammes per minute when given full air
 but more typically 12-20 gm/min.
 
 I have in the meantime acquired a digital scale capable of holding the
 entire stove/pot/fuel load so we can watch the mass change as time passes.
 We were able to use this.  The total mass of the loaded stove during a test
 is 10-11 Kg.
 
 Some things are clear from the test burns:
 
 1)  The gasifier stove (IDD) requires a fuel which is unobtainable in this
 region.  It worked well at the relatively low power that it has.  It burned
 very cleanly once we got it smoking and burning properly, though it took a
 long ime to get the fuel hot enough to 'charcoal'.  More than 30 minutes
 actually.  The place is humid and the fuel seemed to be suffering from that.
 Air drying briquettes this month has been difficult.  The American fuel is
 very consistent.
 
 2)  The Moç briquettes are well compacted and strong - highly transportable.
 They would not work (ignite) in the round grate of the Basintuthu when there
 was no air passage around them.  We broke them up and they worked well
 albeit with a pretty low power output.  I have some more sample briquettes
 from them without charcoal and I will give some a try in the coming week.  I
 suspect they could use more sawdust and less paper.
 
 3) There was no discernable difference between the New Dawn briquettes
 without holes and with in terms of lighting ease and burning
 characteristics.  Perhaps some difference will show up on the scale which
 can show 2 gm changes in the total mass.  I expected a slightly slower burn
 because of the lower surface area.
 
 4)  At a fuel consumption of 12-16 gm / min the Basintuthu was (apparently)
 boiling off about 100cc of water per minute at 98 deg C.  I thought this was
 unexpectedly high.
 
 More later...
 
 Regards
 Crispin
  >>

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