Crispin (adding "stoves" in the belief you wanted yours to go there):
Keeping all of yours this time so others can see your reply to mine of this AM.
Thanks for complete reply - just few follow-up questions below in Bold
.
----- Original Message -----
From: "Crispin Pemberton-Pigott" <[email protected]>
To: [email protected]
Sent: Wednesday, August 4, 2010 11:09:54 AM
Subject: RE: [Stoves] Coal stove testing in Ulaanbaatar - 2 pictures
Dear Ron
This is based on the work done with James Robinson and Prof Harold Annegarn at
the SeTAR Centre lab at the University of Johannesburg. The SeTAR Lab is better
equipped as they had a bigger budget and they have a prototyping workshop which
we do not have here.
Both are capable of measuring condensed particulates without measuring water
droplets. The spreadsheet analysing the outputs is of course the key to
delivering meaningful evaluations of stove performance. We have penned papers
(three I think this past 12 months) on the subject of heterogeneous testing
protocols. I have mostly done the emissions calculations and James has done the
variance and statistical work.
[RWL1: Can you give cites (or better attach the papers?)
Late last year we trained 20 people from 7 universities in Africa how to
conduct basic tests and how to use the spreadsheet. They are being provided
some test equipment including a hood.
[RWL2: Fantastic. Who is paying for this really important addition?]
Regarding the hood, yes we can test under a hood though it is not relevant to
Ulaanbaatar. Almost all the testing done at the SeTAR Centre has been under a
hood. The whole setup is not quite complete there. We will be adding a
condensate scale shortly. This means that the steam from the pot(s) will be
collected on a scale so that the mass of the water remaining in the pot can be
determined in real time without touching the pot, as well as the mass of fuel
burned. With stoves like John Davies’ which has a pot covering an open hole,
this means more accurate determination of the thermal efficiency when the
combustion characteristics are changing (especially early in the fire) without
lifting the pot (which disturbs the fire and changes the draft).
The protocols are very straight forward because the computer tracks everything
that takes place. It is easy to invite people to operate their stoves
themselves. We just watch and record. Afterwards we can often see when things
were going well or badly and can determine why and what to do about it.
To give you an idea of how valuable this is to the designer (recognising that
John has mentioned it with thanks before) I give this example: A stove
developing NGO asked for assistance and showed us a stove that was quite
powerful and well made. It had a CO/CO2 ratio of 5.6% - about 3 times the legal
limit. It looked like a good burn but the CO level was quite high and the
designer could not go further without emissions testing. Using only the
controllers provided for primary and secondary air, it was possible to reduce
the CO/CO to 0.5%.
[RWL3: Sounds like either TLUD or BLDD?]
>From the results of multiple tests with a range of power and fuel levels, it
>because clear what the design flaws were in the combustor. We then constructed
>a slightly modified combustion area which produced a best figure of an
>additional order of magnitude reduction to 0.02%.
[RWL: I would have no idea how to make this big a difference with only
"slightly modified". Can you say a bit more? Changing the flame height below
the pot come to mind, but most people should know that already
In other cases we have located good potential in stoves that looked average or
‘bad’ using this approach.
[RWL: Same question - what sort of changes? ]
About comparable labs – I am not sure. There are certainly better labs with
better equipment, but it seems there is a serious problem with knowing what to
do with the numbers recorded. As I have mentioned before there is a major
disconnect between methods used to measure outdoor air quality and stack
emissions. There is a lot of equipment available for outdoor air measurements
and very little that can deal with stack concentrations with poor combustion
(baselines). The formulas often used for calculating performance assume that
the combustion will be quite good. All this together means that off-the-shelf
tools both for measurements and calculations often give misleading results. It
can take time to convince people the issues are real because the book says…
[RWL: Thanks again - very informative. Ron]
Regards
Crispin
++++++++
Crispin:
I'm impressed by the UB lab. I know nothing about comparable labs around the
world. Is this apt to be better than others for stove testing or are there
similar?
It seems you need a chimney. Could you operate this lab with a vent hood?
Good luck with the startup this week.
Ron
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