[Stoves] Heterogeneous testing protocols

Wed Apr 25 22:53:07 CDT 2012

Dear Testing Friends and Appealing to Peter Verhaart for comment (because
you were there!)

I have been looking over the history of stove testing and it is compelling
that the HTP was used for reporting stove performance as early as 1982-3.
There are a number of references to it in
http://www.cookstove.net/others/fuel-economy.html with a number of citations
from Prasad and Verhaart as well as Piet Visser.

There are some Sankey diagrammes and also inherent heat flows. These are
useful for determining stove performance in a way that allows useful
predictions of field performance to be made based on laboratory tests. Alex,
See Fig 12 and 13. Is that what you have in mind for system analysis? Is
there software or a function in Excel that can produce that automatically?
It could be built into a stove design tool.

I am attaching some performance curves produced created from a set of more
than 80 tests of three stoves. The relationship between power and pot size
is clearly visible for each stove. If you want to know how it will cook your
favourite 'burn cycle' you can make a calculation. I am suggesting this is a
useful extension of the good works done in Eindhoven.

The advantage we have these days is that getting precise emissions
measurement is much easier, as is logging mutiple sets of data in real time.
The resulting displays are easily generated and optimal conditions
identified quickly.

So my question is how did we go from conducting really good test and stove
analysis with really valuable heterogeneous characterisations in the early
1980's to a simplistic water boiling test in 2012? It is clear from the
works pouring out of Iowa State for the past 5 years that WBTs are not
helping us much in providing useful information - nothing like what we used
to get before and what we an get now from heterogeneous tests.

So my question to Peter Verhaart is, what do you think about the current
state of affairs? How do we recover from it?

Grant B-T, if you have time, what are we going to do to revive testing to
the point that a programme manager can make an informed choice about stoves
before rolling something out? I am sure you know the systematic error level
in the WBT's is over 30%.

Dr Nate Johnson, you have beat your head against this wall and surely have
some advice to take us forward. The industry is getting stuck even as the
funding available for stove projects grows by the millions. Never has so
much stove money been directed by so little meaningful information on the
performance of the products being promoted. This has to change. In fact it
has to be restored to its former glory using the new tools and understanding
that has developed in the intervening years.

Interestingly there is a reference at the very end of the article at
http://www.cookstove.net/others/fuel-economy.html to the carbon balance
method of testing. This is the method used at the SeTAR Centre and it is not
an accident. Most EPA-like methods use a hood (or cabinet) and mass (or
whole)-flow calculations, though EPA does use carbon balance methods for
vehicles. 

The issue is precision and accuracy.  The systematic errors together with
the experimental errors have to be less than 7% to place a stove securely on
performance tiers 20% apart. That is basic math. In order to do this in
affordable labs, I suggest that it will require a set of single purpose
tests performed in an HPT manner. The attached chart is one way to provide
that information.  

Testing costs a lot.  Money is changing hands. There is little point in a
lab providing test results that can be challenged if the stoves turn out not
to perform in the band claimed. The more complicated and imprecise the
assessment task, the greater the potential for failure to perform.
Reputations are on the line. We have to provide better quality
characterisations of performance (including durability, safety and social
acceptance).

Serious stuff.

Regards to all

Crispin

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20120425/b8afa170/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Three stoves, thermal efficiency comparison April 2012.JPG
Type: image/jpeg
Size: 151021 bytes
Desc: not available
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20120425/b8afa170/attachment.jpe>