[Stoves] new article

Thu Feb 17 14:15:23 CST 2022

Dear Andrew

I read it a carefully in places and skimmed others. The salient conclusions are that there was no significant correlation between the amount of fuel burned and the indoor PM level. There was a correlation with the opening of the door to feed fuel.  That was a finding worth doing something about.

A well designed stove doesn't emit anything when the door is opened. It pulls air in. They do not say that.

A missing part of the study is that they didn't not related occupation of the room to PM, whether there was a stove at all, and whether it was burning.   The measured values of PM are very low.  If you are measuring and discussing peaks (which they do because the averages are not very interesting) it is worth noting that walking across a carpet can create a peak of 200 µg/m3.

For comparison outdoor PM2.5 in Ulaanbaatar peaks at 3000, even 4000.  It is much cleaner indoors than out, undermining the idea that outdoor PM is always a source of the indoor air pollution.  UK homes are really clean indoors.

Regards

Crispin

-----Original Message-----
From: Stoves <stoves-bounces at lists.bioenergylists.org> On Behalf Of ajheggie at gmail.com
Sent: Thursday, February 17, 2022 4:00
To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>
Subject: Re: [Stoves] new article

On Wed, 16 Feb 2022 at 04:54, Ronal Larson <rongretlarson at comcast.net<mailto: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://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.mdpi.com%2F2073-4433%2F11%2F12%2F1326%2Fhtm&data=04%7C01%7C%7C46ff5aed97964407d35e08d9f2053bb1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637806926569616120%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=SAiZY4Q3KDg%2FvsTpzy2U7tsvqZWnxb8xtnFCn2b3jrU%3D&reserved=0

>

>

> 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

_______________________________________________

Stoves mailing list

to Send a Message to the list, use the email address stoves at lists.bioenergylists.org<mailto:stoves at lists.bioenergylists.org>

to UNSUBSCRIBE or Change your List Settings use the web page

https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Flists.bioenergylists.org%2Fmailman%2Flistinfo%2Fstoves_lists.bioenergylists.org&data=04%7C01%7C%7C46ff5aed97964407d35e08d9f2053bb1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637806926569616120%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=DV%2Bolr947k8vwWjAGFAtbfvF2aJA517jG9sYjVR5YfU%3D&reserved=0

for more Biomass Cooking Stoves,  News and Information see our web site:

https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fstoves.bioenergylists.org%2F&data=04%7C01%7C%7C46ff5aed97964407d35e08d9f2053bb1%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637806926569616120%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=hb0NEp0PXnMcjY5W9xnY5Es2wbyaXA0FV1Zr3ZaGhRQ%3D&reserved=0

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20220217/a461155c/attachment.html>