Re: CO meters (again)

["Tom Reed" <tombreed@attbi.com>]

Dear Tami, Crispin and All:

You inquired about measuring the air flow on the hood and suggested using a
SMALL fan.  We use small fans on our WoodGas stoves and I measure the air
flow produced (at pressures of < 0.1 inch water) by attaching a VERY light
weight plastic garbage bag around the fan and measuring time to fill and
volume.  I'm sure your fan could handle this.

TOM REED                   BEF STOVEWORKS
----- Original Message -----
From: "Tami Bond" <yark@u.washington.edu>
To: <stoves@crest.org>
Sent: Sunday, September 22, 2002 1:18 PM
Subject: RE: CO meters (again)


>
> Crispin,
>
> > I do have the capability to weight the entire stove to 2 grams and we do
> > watch the fuel burn and the water temp rise. This is very good for the
short
> > time (3 or 4 mintes) until the water starts boiling and then it is a
guess
> > thereafter because some of the loss is water and some is fuel.
>
> Bryan had lots of good ideas here (suspending pot etc). Another thing you
> need is a measure of flow rate through your hood-- I assume you have a
> hood collecting the exhaust. Since you are measuring the CO after the
> stove exhaust has entrained some air, the concentration is affected by how
> much dilution has occurred. To remove that effect, and to allow you to
> calculate total CO emitted, you have to measure either volume flow rate at
> the point of CO measurement, or CO2 at the point of measurement. (Another
> way to do it, which has been discussed on this list, is to dump the
> exhaust into a known volume. But this does not allow you to look at your
> transients very well.)
>
> Best thing to do is put a really light draft on the hood, like a little
> blower. Is this possible? You need to make sure you are collecting all the
> exhaust, but not provide enough draft to affect the combustion. Then you
> have to measure the flow. The cheapest way I have found to do this is to
> attach a 6" flow grid ($25) to a pressure transducer with an analog
> output ($40). The flow grid gives you a better and quicker idea of flow
> than a pitot tube traverse. Anyone have a better idea?
>
> > As I want to measure the CO and CO2 from a cold stove being lighted
(which
> > is when the combustion is worst) I will have to have something that
> > stabilizes in a lot less than 11 minutes becase that is three times as
long
> > as a typical test!
>
> I agree with you and with Bryan that we want to know something about
> transient operation and especially specific actions. We might get more
> benefit out of working on specific combustion phases rather than the stove
> as a whole.
>
> Even if the response time refers to temperature and not CO, the long
> response is a problem, because the temperature will change when you light
> the stove. I am not sure, though, that another electrochem cell will fix
> the problem. I wonder how much of a comparison between two sensors is
> governed by one company being more honest or conservative than another,
> rather than actual performance. Let's see if we can get that issue
> straightened out. I think I will send Onset a message and I hope they do
> not get besieged with similar ones.
>
> > It is possible to use waste heat from the fire to preheat and dry out
more
> > fuelwood and if it is worth it, we can do that systematically.
>
> I think this is a really good idea. I have heard that people do that in
> some parts. Thanks for the reminder that the stove-fuel-cooking can be a
> system with more parts than a combustion box and longer timescales than
> dinner!
>
> Last: Bryan mentioned the need for calibration. Yes we need this, but as
> cal kits often run into the several hundreds of dollars, what shall we do?
> I can't think of a better idea than having a central calibration station
> where sensors get returned every year. The shipping would be much cheaper
> than the certified cal gas and much less training would be required.
> Ideas??
>
> Tami
>
>
>
> -
> Stoves List Archives and Website:
> http://www.crest.org/discussion/stoves/200209/
> http://crest.org/discussiongroups/resources/stoves/
> >
> Stoves List Moderators:
> Ron Larson, ronallarson@qwest.net
> Elsen L. Karstad, elk@wananchi.com www.chardust.com
>
> Other Biomass Stoves Events and Information:
> http://www.crest.org/articles/static/1/1010424940_7.html Bioenergy
> http://www.crest.org/articles/static/1/1011975339_7.html Gasification
> http://www.crest.org/articles/static/1/1011975672_7.html Carbon
>
> List-Post: <mailto:stoves@crest.org>
> List-Help: <mailto:stoves-help@crest.org>
> List-Unsubscribe: <mailto:stoves-unsubscribe@crest.org>
> List-Subscribe: <mailto:stoves-subscribe@crest.org>
> >
> For information about CHAMBERS STOVES
>
>http://www.repp.org/discussiongroups/resources/stoves/Chambers/Chambers.htm
>
>



-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/200209/
http://crest.org/discussiongroups/resources/stoves/
>
Stoves List Moderators:
Ron Larson, ronallarson@qwest.net
Elsen L. Karstad, elk@wananchi.com www.chardust.com

Other Biomass Stoves Events and Information:
http://www.crest.org/articles/static/1/1010424940_7.html Bioenergy
http://www.crest.org/articles/static/1/1011975339_7.html Gasification
http://www.crest.org/articles/static/1/1011975672_7.html Carbon

List-Post: <mailto:stoves@crest.org>
List-Help: <mailto:stoves-help@crest.org>
List-Unsubscribe: <mailto:stoves-unsubscribe@crest.org>
List-Subscribe: <mailto:stoves-subscribe@crest.org>
>
For information about CHAMBERS STOVES
>http://www.repp.org/discussiongroups/resources/stoves/Chambers/Chambers.htm