Dear Crispin, Is the PM measured using a pump and filter system? What diameter filter are you using?
Best, Dean On Tue, Aug 27, 2013 at 8:41 AM, Crispin Pemberton-Pigott < [email protected]> wrote: > Dear Friends**** > > ** ** > > I am circulating this as an into to the test methods applied in Mongolia > (and other places). It is a pretty good example of what the main > measurements look like.**** > > ** ** > > The photo is of one of the two computer screens which side by side. On the > top left is the Digital Scale Capture Tool (DSC) available for $50 once off > payment to Jeremy [email protected] (as a thank you).**** > > ** ** > > On the left of the DSC screen is the mass from the scale per 10 seconds. > On the right is the (approx) calculated power in kW reported per minute. > The data is saved to disk each 10 seconds. Multiple copies of the DSC can > be run at the same time, one for each scale used.**** > > ** ** > > Below the numbers screen is the average kW plot so far in blue and the > cumulative mass burned (also so far) curve in red.**** > > ** ** > > Below that is the mass change detected by the scale per 10 seconds. The > value is shifted by the wind and moving fuel but overall as time passes, > the precision is high, about 1 part in 5000. The burn rate (green line) can > be seen to be declining towards zero as the fire burns out. **** > > ** ** > > There are 4 gas readings. This is the minimum if you want PM from a fire. > On the left is the CO2 level in the diluter. The other three are measured > directly from the stack (or hood). The CO is the concentration in the > chimney, in this case. The next CO2 is the CO2 in the chimney and is of > course higher than the CO2 in the diluter. The ratio between them is the > level of dilution, in this case it is 3.232:1. The PM measured in the > diluter is multiplied by the number 3.232 to give the equivalent of the > direct measure from the chimney (which might be too high to measure > directly). The dilution is variable with the turn of a knob.**** > > ** ** > > The O2 on the right is the O2 in the chimney. **** > > ** ** > > Notice that the total of the O2 and CO2 on the right does not add up to > 20.945%, the O2 concentration in the ambient air. This is because there is > H2 burning (from the fuel) and being turned into H2O. That H2O is not > measured on this screen and as you don’t know what it is looking at this > picture, you can’t tell if the equipment is working perfectly or not. Maybe > it is a measurement error, maybe it is diluted by water vapour (which it > is).**** > > ** ** > > The CO is very low at 18 ppm. The value for EA is about 1.67 and Lambda is > therefore 2.67. **** > > ** ** > > 2.67 x 18 ppm = 30. So the CO(EF) is 30 ppm, meaning that if there was no > dilution by air, the CO cell would read 30 instead of 18.**** > > ** ** > > The CO/CO2 ratio is 18/(6.730 x 10,000) = 0.0002674 or 0.0266% (very > good).**** > > ** ** > > The ‘modified combustion efficiency’ is **** > > ** ** > > 6.73/(6.73+18/10,000) = 0.9997 = 99.97%**** > > ** ** > > The kW blue line for power is the running average from the beginning so > the value 11kW refers to the whole test as a whole.**** > > ** ** > > The PM value will be multiplied again by Lambda (dilution) to get a > PM2.5(EF) value. This is the rating that the stove gets. **** > > ** ** > > Quick review: PM reading x dilution in the diluter x dilution by excess > air = emission factor value. This is later multiplied by the mass burned x > the volume of gases produced by the fire based on the fuel analysis. The > result is the mass of PM (and by the same method the CO and any other gas) > emitted during the test.**** > > ** ** > > Because the data is collected in real time, the stove can be tuned to find > the best operating parameters. Sections of the test can be analysed later > to create a plot of how the heat transfer efficiency, for example, changes > with power or fuel condition (etc).**** > > ** ** > > Best regards**** > > Crispin**** > > ** ** > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org > > for more Biomass Cooking Stoves, News and Information see our web site: > http://stoves.bioenergylists.org/ > > >
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