[Stoves] The Economist

Norbert Senf norbert.senf at gmail.com
Mon Sep 10 07:39:40 CDT 2018


Hi Ron:
I don't know of any low cost commercial instruments that might be suitable.
We use the Testo 330-2 for stack gas analysis, and it is around $2,000. We
found lower models of Testo unsuitable, because with wood burning you can
get episodes of very high CO (20,000 ppm) that will shorten the life of the
expensive CO sensor, and therefore you need to have the automatic 10:1
dilution built-in to protect the sensor.

On the PM side of things, we use the Condar portable dilution tunnel, which
is not available commercially but in theory could be built for under
$50.00. The filters are somewhat pricey at around $2.00 each, and you need
an analytical balance to weigh them. You need the gas data from the Testo
to calculate a g/kg PM number. The filters give you other valuable
information, such as the smell, which can tell you whether you have only
soot (OC) or roughly to what degree you have organics.

Actually, Testo used to make a smoke spot meter that we tried out, but
never tried to calibrate against the Condar. We have some info here:
http://heatkit.com/html/lopezy.htm

I have fooled around with measuring white light extinction, which is quite
easy and costs almost nothing. It is real-time, but only gives you a
qualitative measurement, which might be useful for comparing two appliances
or two fueling methods, under the same conditions. I found the recent
information on LEDs from F. Mims quite intriguing, and hope to try it out
this winter. Using Tami Bond's paper as a reference, it looks like you
might be able to measure extinction using IR wavelengths, and scattering
using near-UV wavelengths, which would yield valuable info on the EC/OC
ratio of the PM. However, you'd still need to know O2 or CO2 to get the
dilution factor for a quantitative PM number.

Once you get into get absolute numbers that can be compared between labs,
you need to ask what level of uncertainty/repeatability is acceptable. This
is pretty much uncharted territory in the wood burning realm. With wood,
for example, if you had perfect instruments, what is the test-to-test
repeatability of the wood itself, ie., your fueling protocol? We've done a
bit of work on this on masonry heaters and pellet stoves, which is
summarized here:
heatkit.com/docs/presentation/Repeatability%20Studies%20with%20the%20Condar.pptx

Best ............ Norbert

On Sun, Sep 9, 2018 at 8:31 PM, Ronal W. Larson <rongretlarson at comcast.net>
wrote:

> Norbert:  cc list
>
> I couldn't learn much about the two instruments you mention below.  But I
> sense they are not appropriate for those who are trying to improve
> cookstoves that have to saleablefor less than $50 (better $25).  As someone
> who does testing, any simple low-cost test systems for CO and PM2.5 you can
> recommend for small stoves ?
>
> Ron
>
>


-- 
Norbert Senf
Masonry Stove Builders
25 Brouse Road, RR 5
Shawville Québec J0X 2Y0
819.647.5092
www.heatkit.com
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