[Stoves] A photo of a lab test from Ulaanbaatar

[Crispin Pemberton-Pigott]

Dear Dean

 

Thanks for the pointer. I will check them out.

 

Regarding the ultrafine particles (UFP): I have been looking for a couple of
years at equipment that might be able to cover the range from 3 nanometers
(PM0.003) to PM2.5. From what I have learned it requires a train of 3
machines in a row to get something meaningfully accurate. It is not that
there are machines which can do a section of that spectrum each, it is that
a machine can tell us what the mass is, but not the size. Some can determine
the size but not the mass or density. This is not a general agreement on
whether the number of particles is more important than the total mass,
though it seems to lean towards the number at the moment (because the mass
is so small) but the arguments are shaky. Mass matters, it is just very
small.

 

A train of three machines that can report the mass and number costs about
$80,000. That is too steep for most people. A whole SeTAR lab costs about
$65,000 with a combustion analyser and optical particle counter. With a much
better NDIR machine and a TEOM it costs about $105,000 with the different
being almost entirely the two machines. A test-day would cost about
$600/$1000 to perform.

 

The issue of money, if overcome, is not the whole solution. Collecting and
quantifying UFP on a mass basis is seriously difficult. In many countries
there are only a few people who can consistently weigh a filter to within to
1 microgram or less. If we go for number of particles only, there are
serious dilution issues because of the huge range to be covered - the SeTAR
Lab setup can deal with a range of perhaps 2 million to 1. But it is going
to struggle with getting 10 or 15 g/cubic metre smoke predictably down to
<100,000 ultra-fine particles per cu cm from tens of billions.

 

Stove emissions are about the hardest thing to quantify because it boils
down to being able to measure anything anyone could burn. At least in
industry people have a clue what they are burning from day to day.

 

Regards

Crispin

 

Dear Crispin,

 

Sounds great! I agree that light scattering is better for some uses although
I have been rattled by certain stoves (mostly fan stoves) that had a lot of
smaller PM that was missed by the laser.

 

But for improving a stove I believe that light scattering is OK just not for
comparing stoves with different types of fires.

 

The big filters can be purchased from HI-Q Environmental Products Co. at
www.HI-Q.net <http://www.HI-Q.net> 

 

We are doing a lot of stove improving and, like you, I believe that the
major reason for having emissions equipment is to get to better performance.
Testing should not be a good in and of itself. There are too many serious
problems needing to be addressed, as you say.

 

All Best,

 

Dean

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