[Stoves] Pasifier Video

[Crispin Pemberton-Pigott]

Dear Stovers

Thanks Alex for the latest report.  So: here is at least on empirical number
from Alex's combustion analyser that confirms the output from a reasonably
correct application of the Siegert formula. Well done, Siegert.

The SeTAR test protocol makes this calculation in real time (actually every
10 seconds) making it possible to chart the thermal efficiency during the
burn. If you are developing a stove the usefulness is obvious: you can
change the stove while it is burning (like lowering the pot a little) and
see the effect it has on the efficiency.

The normal result is a pretty jumpy line because of the 'snapshot' nature of
the readings. 

What we found useful is to plot the sum of the performance to that point by
which I mean a mass-compensated sum of the efficiency numbers. By the end of
the test it shows the average efficiency for the whole burn of all the fuel.
This is useful from the point of view that one can compare space heating
stoves over a period of a whole burn, not just when things are going well.
The end result is meaningful, in the sense that it predicts fuel savings
relative to a baseline even if the stoves, fuels, power, burn time and
refuelling method are different in each case.

At an absolute minimum you need the O2 level, the temperature where no more
heating is taking place (such as the bottom edge of a pot, the CO and the
fuel type to apply the Siegert formula to get a % thermal efficiency. If you
want to do the running average calculation the stove has to be on a scale
because you need to weight the efficiency numbers with the mass of fuel
burned during each interval.

Regards
Crispin