[Stoves] Particles and particle types (was Charcoal Making Stove)

[AJH]

On Tue, 31 Oct 2006 20:58:59 -0600, Tami Bond wrote:

>Andrew, if you want to keep it on-list that's fine. I somehow thought 
>you had taken it off-list. Go ahead and forward if you like

Yes Tami, it was probably my mistake, I was thinking all messages were
now going to the whole list so hadn't checked, probably because I was
replying to a message that predated the change in "reply to:" address.
>
>> The thing is wood ash is still 50% silica even if this is only 1% of
>> the raw wood. As you may have gathered I play with forced air burners
>> and I do see fly ash blown out, even to the extent that I have
>> considered making use of it with an automatic ash collection system.
>>   
>I agree that it could be a concern but I think the carbon is also a 
>health concern. At this point I am more concerned about reducing total 
>PM mass and later we can worry about what it's made of. That may be a 
>narrow view.

It's like fractals, you get drawn in to deeper levels of intricacy,
occasionally you need to draw back and see the big picture and how
insignificant the splitting of hairs may be.

From the recent posts reporting on your work and contributions to
other lists (how many are there, I only belong to this one in this
field?) it looks like we've moved on a bit from the early days.

First we aimed for complete combustion because it was more fuel
efficient.

Then we looked at better heat transfer because it used less fuel.

Then Kirk Smith pointed out the health dangers of indoor wood smoke,
principally in relation to acute respiratory infections of infants
from particulates. Better combustion helps address this.

Now you quantify the significant contribution black particulates, some
from from cooking, could contribute to climate change. I've probably
missed how significant effect this is compared with the doubling of
CO2 concentrations since the industrial age. Again this can be
mitigated by better combustion.

I'm beginning to get the message that perhaps naturally aspirated
stoves will not reduce particulates well enough for this last effect
and that my view that the exhaust was "good enough" needs rethinking
in this light. Or am I misinterpreting the interest in the cleanliness
of forced draught stoves?
>
>>
>> In the early stages the
>> propane contributes a lot of the heat energy but over time I can
>> reduce it and still maintain 700C (note this may well be an under read
>> temperature) as measured by my digital multimeter and a K type thermo
>> couple. 
>...this makes a lot of sense but it still seems there are so many 
>variables changing, that the temperature might or might not be the 
>determining factor.

Yes
>You could probably think of a way to isolate it, though.

Not at the moment!

AJH