[Stoves] Stove testing methods

[Paul S. Anderson]

Stovers,

The messages between Crispin and Christa could help us restructure some of our
stove testing.

<< Snipping much >>,

Crispin wrote:
  Baldwin's suggested solution to this was to take the lid off the pot to
  force some evaporation to take place throughout the test thereby stabilising
  his results.  His book confirms that he understood the implications of this.
  The problem with this solution is that it creates a situation that is not
  part of normal cooking (in most countries).  It introduces a loss that was
  not there before - a big loss.

Paul replies:
Unless someone shows that the above is incorrect, there is every reason 
for the
lid to go back onto the pot!!!!!  Baldwin's methods NEEDED to force a
considerable amount of evaporation!!!  Our calculations should not favor nor
hurt stoves that boil away excess water.  Any cook knows that if the 
water gets
low during cooking, add more water, a cheap and easy solution for actual
cooking.   Requiring the lid to be off should be simply NOT acceptable 
with our
understanding of what should be in stove testing today.

Quoting Crispin Pemberton-Pigott <crispin at newdawn.sz>:

> Piet Visser showed more than 20 years ago that an open fire can have 
> a thermal efficiency of 33% by feeding it wood chips like a baby 
> bird.  Few modern stoves can match that performance!

Paul replies:
While Visser's experiment was not a "fan-blaster", it was something like the
operation of the "trickle-fuel" method.  The inconvenience of feeding 
fuel in a
trickle is extreme (unless mechanized as in pellet stoves), but perhaps 
there is
something about burning only very small quantities of fuel that merits more
study.  Interestingly, the fine-tuned operation of a Rocket-elbow stove (as
seen at Stove Camp) is with multiple small diameter sticks with just the tips
into the combustion area.

Crispin wrote:
> I feel that in the long run the less attention a stove needs, the 
> more likely it is to be used correctly.  This could possibly form 
> part of a stove assessment: how many minutes out of the standard 
> cooking test does the operator have to be present to attend to the 
> demands of the stove?  It could be called a 'time demand coefficient' 
> expressed in % terms, or hundredths of the time of the test.  It 
> could be something like, the number of times the stoves needs 
> attention multiplied by the number of minutes of actual attention, 
> perhaps a factor on one or the other.

Paul replies:
Absolutely excellent suggestion.  Even if the "time demand coefficient" (TDC)
(also called the "Attention Demand" or AD by Crispin) is not fully integrated
into the emissions or fuel comsumption measurements, the TDC could be a scale
like the one Nate Johnson did for stove safety.  Something like:

1.  Light and leave = 10 (electric stove with clock timers, etc on 
every burner

2.  Light and minimal attention = 8 (can observe from 2 meters away, with no
more that one touch of short duration per 15 minutes of operation.  Maybe a
good charcoal stove could get an 8?? )

3.  ...
.
.
6(?).  Nearly constant attention = 2 (less than one minute intervals between
required attention, as seen in the trickle-fuel stoves.)

Nate got a Masters thesis out of his work.  The TDC research would be equally
worthy of efforts and recognition.

Crispin wrote:

> Fuel preparation could also be counted so that the time and 
> inconvenience required to saw, split, pulp, chip or otherwise 'size' 
> fuel is assessed.
>
> The numbers will show you why people really like charcoal.  The MCS 
> has a fuel preparation time of about one minute and an attention 
> requirement of about zero for the next 90 minutes.

Paul replies:
About fuel preparation, there will need to be much discussion.  SOMEBODY put a
lot of time into the charcoal preparation, but the cook has an easier job.

Wood chips can be inconvenient when manually made from large wood, but quite
easy when small-diameter twigs and brush are available.  And if an 
agricultural
wastes such as cherry pits or coconut shells are plentiful, making great
small-fuel can be much easier than hauling big branches from forests that need
protection.

Therefore, let us not favor one fuel over another.  Rather, let's just make a
side note about the requirement of availability of an appropriate fuel, 
and let
the preparation of fuel be factored into the cost of the fuel.

Crispin wrote:
> Fuel (and stove) Preparation + Attention Demand + Fuel Consumed, 
> independent of cost (because different markets exist everywhere).
>
> That can be reduced to Preparation+Attention+Consumption = The PAC Test.

Paul replies:
Seems like E for Emissions should still be there somewhere, making it a PACE
Test.

And the Preparation part is actually the availability of the fuel (including
cost???).

All of this certainly deserves further serious consideration.

Paul

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