[Stoves] new article

[ajheggie at gmail.com]

On Wed, 16 Feb 2022 at 04:54, Ronal Larson <rongretlarson at comcast.net> wrote:
>
> List and Kirk
>
>
> List:
>
> 1.   . This paper just a few months old.  Not usual for this list (normally only cook stoves here.), but has lots of particulate data and information on sensors.  Of potential interest because of the large amount of wood that can be consumed - and likely least cost if wood is local - as on many farms..

I had a quick read of the report, as you say it relates to room
heating stoves in Sheffield England and the bulk of it seems to be
about calibrating the instruments.

Basically the study used a few households in the city that used wood
burning stoves on average about 4 hours a day and measured the indoor
particulate levels and outdoor  particulate levels with the sensor
mounted high on the outside of the building. The results were not
presented in a way I could easily follow but the salient points are
that PM10 and PM2.5 concentrations go up indoors when the stove is
running despite the flue gases going up the chimney and the room is
"flooded" with particulates  when the stove is reloaded.  This is much
what I have observed with my own indoor stove and my little USB
particulate sensor,There is no distinction between fly ash
particulates or black carbon ones. I would be interested to see
others' comments.


It shows that even in a modern house particulates are a problem  with
wood combustion in a society where ambient particulate  levels have
reduced drastically over the last 25 years.

There will be significant differences as the air changes in a british
house in winter will be less than a cooking area in a warmer clime.

It also points to;

Opening the door of the stove slowly while flames are present

Reloading infrequently and only onto hot coals ( although re
establishing a flame quickly is vital to avoid smouldering combustion)

The value of masonry stoves which are loaded cold, fired fast and
re-opened when cold but for the fact british houses tend to be a bit
small to accommodate their increased volume.

In my case I only heat my small house with wood, so the fire is lit
16hours rather than 4 which indicates the sheffield houses  use other
heating as well. My house is typical of older houses here  at 180
years old and with solid brick walls which do not lend themselves to
retrofit insulation especially as 100mm interior wall insulation
becomes a serious encroachment on a small room.
>


> Indoor Air Pollution from Residential Stoves: Examining the Flooding of Particulate Matter into Homes during Real-World Use
>
> Non-fee at.   https://www.mdpi.com/2073-4433/11/12/1326/htm
>
>
> 2.  I think there is fair chance we (globally) will soon see some users of wood stoves asking about making biochar while cooking and heating.  Can Kirk and anyone else report on how much difference there is between a char-making stove and the type we can assume is here?   I believe staff at Berkeley or Stanford could barely measure any particulates with Kirk’s stove.  How low can we go compared to the numbers here (which were about  double or triple outdoor numbers.)

Most modern woodburning stoves here follow the same format, they have
a constant small secondary air supply to maintain a flame (to avoid
smouldering), a fire chamber insulated with refractory to maintain a
high combustion temperature, no primary air and the major secondary
air flows down  over a transparent door window after being preheated.
They lend themselves to top lighting.

Because the secondary air  flows down and then to the back of the
combustion it first meets offgas and as long as a flame is present
this burns preferentially to any nascent char. So as long as you load
very dry wood it rapidly forms a thick bed of glowing coal.  During a
day long burn a lot of char becomes buried in ash and it can be
removed and quenched the next morning.

It would not be a very big step to redesign the hearth area to retain
a good percentage of char dropping down into a sunken hearth, much the
same as any other flame cap device.

The amount of char these stoves could produce is dwarfed by the amount
of char that could be made from the "green waste" streams currently
collected by civic undertakings and composted here.

Not at all related to cooking with wood but we have been so quiet lately.

If anyone lurking has any burning questions please fire away.

Andrew