[Stoves] [stove] Comparison of stove testing procedures

Fri Mar 18 09:00:07 CDT 2016

Philip and All

There are a few other papers comparing the Chinese WBT to other tests,
including the GACC WBT, the Indian WBT and the CSI Test. We could as well
refer to these.

I have attached Rani, Kandpal and Mullick 1992 which examines the inner
workings of several test methods including the VITA's test, identifying
systemic issues some of which had been carried into the WBT 4.2.3. It is the
earliest paper I can find that demonstrates that there is no connection
between the amount of water in the pot and the emissions. It supports Zhang
Y (2014) in concluding that the low power metrics of the IWA tiers have no
physical basis. This being the case, I expect there will inevitably be
problems making comparisons between test results because comparing valid
metrics with invalid ones is going to give results with some element of
randomness.

In two series of tests run at the CAU lab in 2015 and 2014 during the S4G
conferences using various test methods including the two named in the paper
below, results were recalculated to demonstrate that all the tests were in
significant agreement once invalid calculations were corrected. The single
outlier was the Chinese Water Boiling efficiency result which was
consistently higher (by >10% of value) in large part because (we think) the
retained heat in the stove is allowed to be applied to evaporating water,
something not done in the other tests which are ended by time, not
temperature.

It remains to be seen if the metrics in the IWA tiers were first correct to
the Chinese ones, or if the Chinese ones were corrupted by making them match
the IWA. I will have a look.

The Rani et al paper is a Permagon Press paper, and I found the whole paper
posted on line so I don't know what to say about the copyright. Permagon
seems to have been taken over by Elsevier. There may have been a time when
it was available open source. If not, obtain your own copy.

If the file is too large to attach for the general readership here, it could
be posted in the Stoves site. I recently found it is available for sale here
<http://www.sciencedirect.com/science/article/pii/0196890492901067> . My
previous searches did not locate this source.

Significantly, the analysis does not mention the pointlessness of the
'simmering efficiency' metric, much in vogue at the time. They didn't catch
that.  It does clearly identify the problem with the 'specific' performance
numbers for low power and reports the result of their experiment seeking to
prove whether or not the mass of water in the pot affects the need for heat
to keep it at a constant temperature. This is basically the same experiment
performed at a much higher resolution by Zhang et al in 2014 (there is no
detectable effect at all). Jim Jetter reported replicating the experiment
with the same conclusion. The 'specific' numbers were introduced in 1987-ish
by Sam Baldwin replacing the legitimate metrics of the Feu de Bois test
(1982).  All this is covered in the paper "From WBT to WHT" at the C4D
website.

With respect to the emission rate and total, unless the WHO model of
exposure is validated somehow, I can't see how it is possible to claim that
a stove 'cannot' or 'does not' meet some indoor air exposure advisory limit
because that depends on the stove, its level of excess air and the kitchen
ventilation.  We are testing stoves, not kitchen architecture. This is a
problem the WHO technical committee has to deal with when making claims
about what is 'clean enough'. They have proposed using a single box model
for emissions that assumes all emissions are spread through the room evenly
and affect all occupants. They also experimented a bit with a three-box
model that predicts less than half the exposure.  Which was sued in the
paper below? Do either support the long-standing claim (1999) that 'solid
fuels cannot be burned cleanly enough' to be used for cooking?

When postulating the rather obvious solution of putting a hood or chimney on
the stove to transport emissions outside, two replies are made: one is that
outdoor emissions will come indoors and might cause too much exposure, and
that (all) chimney stoves leak emissions into the room. When checking the
parameters used in this model, I found that the leakage estimates were very
high (0-50%) and pollutant emissions from 'chimney stoves' were assumed to
be baseline level, i.e. that there were, and are, no improved chimney
stoves, while there are improved non-chimney stoves.  Is that reasonable?  

The assumed leakage is enough that the single box model will always
calculate an exposure that is above the new WHO limit. In short there are no
measurements behind the claim for exposure, it is a model with assumptions
that pretty much guarantee failure of all stoves. It has already been
reported here that there are natural draft pellet stoves burning cleaner
than LPG stoves, so I cannot see why solid fuels are assumed automatically
to be 'too polluting' to use in any kitchen but LPG is OK.

It should be obvious that if one has a clean burning modern stove and it is
connected to a chimney and it happens to leak some of its tiny bit of its
emissions into the room, there is virtually nothing in the room. Because the
assumptions in the exposure model virtually assure that all stoves will
fail, we should await validation of the model before accepting its exposure
claims. 

If the paper remains pay-walled perhaps Kirk or one of the principal authors
can comment here on how the metrics were handled because that is key. With
respect to the exposure model, we could ask for input from Nikhil Desai or
other experts on what data would be needed and how to determine exposure
based on stove emissions and kitchen architecture.

Regards

Crispin

++++++++

Unfortunately the reference is behind a paywall.

Prof Philip Lloyd

Energy Institute, CPUT

SARETEC, Sachs Circle

Bellville

Tel 021 959 4323

Cell 083 441 5247

PA Nadia 021 959 4330

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
Paul Anderson
Sent: Friday, March 18, 2016 3:22 AM
To: stove at lists.berkeley.edu <mailto:stove at lists.berkeley.edu> ; Stoves and
biofuels network
Subject: Re: [Stoves] [stove] Comparison of stove testing procedures

Stovers,

Below is the abstract of a significant comparative study done in China.   We
thank Kirk Smith and his Stove list (different from StoveS) for the
information.

Spoiler alert:   Here is the punch line from the abstract: 

Statistically significant differences 

between the two [China and Internatonal WBT] protocols indicate the need for
further efforts in emission tests and methodology development

before the release of a well-accepted international testing protocol.

Yes.  Should we be surprised.   It seems that some entities in the
international leadership of clean cookstoves might be pushing for one test
without sufficient attention to alternative testing methods.

Note (in abstract) that: 

With longer burning duration and higher 

power, the Chinese WBT had statistically higher efficiencies, gas
temperature, and lower pollutant emissions

Sure!!!   Change the duration and power, expect different test results!!!   

What is clear to me is that there should never be only one set of tests.
People around the world have very different ways of cooking.  High power in
China, plancha stoves in Central America, two-arm cooking of thick foods in
parts of Africa, long-simmering bean-meals vs. quick boil of rice meals, and
on and on.   The people we are trying to serve want solutions that are
appropriate for their circumstances. 

Observation:  There seems to be a slow-down in the seeking of stove testing
at the major testing centers that have equipment.   I can be shown to be
incorrect if any testing centers would give us some statistics of numbers
and types of tests that are being requested.

Of course I like the importance of emissions testing because the TLUDs and
other micro-gasifiers consistently give superior results.   But most funding
in the past has gone to less-qualified stoves.  

Paul

Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20160318/96c3dea1/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image002.jpg
Type: image/jpeg
Size: 4280 bytes
Desc: not available
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20160318/96c3dea1/attachment.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Preliminary study of WBT procedures used for performance evaluation Rani et all 1992.pdf
Type: application/pdf
Size: 937290 bytes
Desc: not available
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20160318/96c3dea1/attachment.pdf>