[Stoves] Personal Particulate Monitor

Thu Sep 13 14:53:06 CDT 2018

Dear Norbert

The readings were matched several times. I had not done a calculation of the total mass per kg. I think we can assume the EA was low. The highest I ever measured was 17 g/m^3 which was for a stove claimed to be 'improved'. That level was temporary, not sustained. The worst baseline stove measurement was about 8g/m^3 (undiluted).

We normalize to 0% O2 in all cases but I can't guarantee that JICA did. I recall they use 11% or thereabouts. The fact that people use different normalizations is why we always use 0% (undiluted for all reports).

Obviously the coal has nothing to do with these terrible numbers. The same coal in a crossdraft stove produces so little PM it is hard to detect it against the background ‎even when the background is low.

In some respects the approach to improving ambient air quality is confused with misconceptions.

Regards
Crispin

Andrew:
Yes, I was thinking about this after our previous exchange.
I'd guess there is no fan on your device. It should be easy to check if there is a flow through the
intake orifice.
It should behave more like a smoke detector - the air has some degree of "cloudiness"
and it doesn't matter if the air is moving or still.
With a dilute mixture and measurement of individual or cumulative scattered light "hits" on a
sensor, it is related to particle concentration in the air which is unchanged by velocity.

For the dilution scheme that I described, I had forgotten about this. You'd actually need to
add a small fan if you wanted to try this approach, in order to establish a flow that can be diluted.

Crispin:
Earlier you mentioned a flue gas measurement of 30,000,000 ug/m3 PM in Ulaanbaatar. That converts to roughly
350 g/kg, or more than 1/3 of your fuel leaving the stack as PM (normalized to 13% O2), way off the map of anything I
have ever seen or hear of. I'm not really familiar with coal or high fly ash, so can't hazard a guess - seems almost impossible.

Norbert

Message: 2
Date: Thu, 13 Sep 2018 09:30:53 +0100
From: Andrew Heggie <aj.heggie at gmail.com<mailto:aj.heggie at gmail.com>>
To: Discussion of biomass cooking stoves
        <stoves at lists.bioenergylists.org<mailto:stoves at lists.bioenergylists.org>>
Subject: Re: [Stoves] Personal Particulate Monitor

I've made the subject a bit more appropriate, comments below:

(snip)
> I doubt whether the flow speed through it would affect the particle concentration, ie if you
> put a sampling tube on it.

This confuses me somewhat, surely to measure concentration one needs
to know how much air is passing the sensor and then count the light
reflected off particles. or is there another way of knowing a
concentration?  I thought perhaps it assumed the fan drew a fixed
volume per second and then the reflections were counted and calculated
as a mass in that volume. If a restriction from a tube reduces the
flow then a smaller volume passes but the sensor still counts the now
lesser number of reflections, giving a lower reading??
>

--
Norbert Senf
Masonry Stove Builders
25 Brouse Road, RR 5
Shawville Québec J0X 2Y0
819.647.5092
www.heatkit.com<https://eur01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.heatkit.com&data=02%7C01%7C%7C245efb9649404a1bf1b908d619aa2f07%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636724616050367720&sdata=vaO1X9Lxc8TYlQJyLulXkMxkzNPWDcnnVXkJ%2Bv2jZdk%3D&reserved=0>
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