[Stoves] Making testing equipment for CO and O2

[IPC]

It is amusing to reflect on the speech made during the award of the Nobel
prize to Nernst in 1920.
"During the combustion of carbon in air no actual work is performed, since
the affinity results only in heat or, as we understand it today, in an
increase of the motions of the molecules. This is indeed, what we are trying
to achieve when we want to use the affinity between carbon and oxygen to
obtain heat."

http://nobelprize.org/nobel_prizes/chemistry/laureates/1920/press.html 

(Dr)Philip Lloyd
Energy Research Centre
University of Cape Town
Private Bag Rondebosch 7701
South Africa
Tel +27 (0)21 650 3896
Fax +27 (0)21 650 2830
e-mail philip.lloyd at uct.ac.za 



-----Original Message-----
From: stoves-bounces at listserv.repp.org
[mailto:stoves-bounces at listserv.repp.org] On Behalf Of Tami Bond
Sent: 04 February 2008 02:27
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Making testing equipment for CO and O2

Hi all,

I *think* that Nernst cells are the same principle as the electrochemical
cells used in most inexpensive CO sensors. However, some of the
electrochemical cells are corrected for interferences (measuring one gas as
another).

I can see a need for measuring O2 in the exhaust of a chimney stove, or the
outlet of a non-chimney stove. O2 is available in most combustion analyzers.
I'm much more in favor of measuring CO2 because (1) it can be directly
traced to the fuel and (2) if you have a lot of excess air/dilution, as you
do above a non-chimney stove, the O2 quickly approaches atmospheric content
and the calculation of excess air becomes very sensitive to small
differences. The calculation of excess air is fairly robust if you are
measuring 5% or 10% O2, but not very robust at all if you measure 19% O2.
That's why we like to measure CO2 directly, and then the CO/CO2 ratio is
better known. We get our CO2 sensors
(infrared) from Telaire and they do take some wiring and calibration. 
These inexpensive CO2 sensors have been available only in the last ~5 years,
and they are slowly making their way into combustion analyzers. 
O2 is still far more prevalent, but again, I think it is much less
appropriate to stove applications.

Tami

*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
Assistant Professor
Arthur & Virginia Naumann Endowed Faculty Scholar Dept. of Civil &
Environmental Engineering University of Illinois, Urbana-Champaign
Newmark Civil Engineering Laboratory, MC-250   (01)217-244-5277
205 N. Mathews Ave., Urbana, IL 61801   USA    fax/217-333-6968



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