[Stoves] [biochar] Charcoal as space filler in TLUD reactors

[Crispin Pemberton-Pigott]

Dear Paul A

 

"[Technical note:   Stove testing should measure separately the emissions
during each of the different combustion modes instead of just reporting
averages that include emissions from two or more combustion modes.   I think
we can do some of that at this summer's Stove Camps at CREEC - Uganda and at
Aprovecho - Oregon-USA where emissions equipment is available.]" 

 

Just on this point, it is fine to call for testing and reporting of
different attributes however I would ask that people consider the difference
between development of a product and the 'testing' for comparative purposes.


 

The reason the HTP method was developed was to rapidly assess what the
conditions were in a stove that produced the lowest emissions and best
performance. At that it has been very successfully applied, most recently in
Indonesia where the improvement of the ubiquitous Keren Stove has seen a
remarkable turn of fortunes in the lab. 

 

The HPT is not more much than a method of recording performance
continuously. It is ideal for the purpose described above. If one wants a
performance number for any period of time it is only necessary to sum the
emissions from time A to time B, or from the beginning to the end of a task.
One of the recent developments has been the application of not an arbitrary
selection of times for the beginning and ending, but to examine where moving
the beginning and end makes any difference to the performance number. If it
does, the metric is probably not 'characteristic'. An example is the
determination of the heat transfer efficiency at any power level. If the
chosen start and finish times change the assessment, then it is probably not
a representative figure because the heat transfer efficiency is a
characteristic of the product, not something that varies.

 

The YDD lab has produced some tests this year demonstrating what a robust
assessment of heat transfer efficiency looks like. Moving the beginning or
ending time by 10 minutes makes no difference to the assessment (no
meaningful difference). Several people have called for other tests that
provide pretty much the same result though they were not based on an HTP.
Piet Visser comes to mind. He likes a long, high power boiling pot heat
transfer number. I call this the hot stove high power heat transfer
efficiency. The same can be done for other power levels provided the pot has
cold, not boiling water in it.

 

Regards
Crispin

 

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