Dear Crispin, Sounds great! I agree that light scattering is better for some uses although I have been rattled by certain stoves (mostly fan stoves) that had a lot of smaller PM that was missed by the laser.
But for improving a stove I believe that light scattering is OK just not for comparing stoves with different types of fires. The big filters can be purchased from HI-Q Environmental Products Co. at www.HI-Q.net We are doing a lot of stove improving and, like you, I believe that the major reason for having emissions equipment is to get to better performance. Testing should not be a good in and of itself. There are too many serious problems needing to be addressed, as you say. All Best, Dean On Tue, Aug 27, 2013 at 11:17 AM, Crispin Pemberton-Pigott < [email protected]> wrote: > Dear Dean**** > > ** ** > > The filter is on the output of the Dusttrak DRX and is inside a canister. > It has a 37mm filter and we have 5 canisters. It can be changed in a few > seconds. There are apparently (not located yet) multiple sources for > pre-weighed canisters that can be fitted that already have a filter inside > and a total dry weight. All that one has to do is weigh the final result > which is a pretty simple approach. I would like to do that wherever > possible.**** > > ** ** > > For comparative testing we do not use the filters. At this time there is > no requirement for absolute measurements (certification against a numerical > target). It is planned that the Jakarta lab will have this capability. It > requires far more cost per test to do certification and the things tested > for will be limited as a result. A certification lab staff complement is > higher and they spend about 20% of their time calibrating equipment. **** > > ** ** > > Even for major expenses that are involved in programmes on the scale of > thousands of stoves, relative performance against a local baseline is > accepted. That by no means says the results are comparable across other > methods. The readings are only as good as the equipment times the protocol > times relevance to the local cultural practises.**** > > ** ** > > Because of the fewness of the labs and the real need at this stage for > real time measurement to assist product developers, it is likely we will > got for real time measurements of PM into the future. The real time > measurement of mass using for example a TEOM 1405 (oscillating > microbalance) is a step up and fits well with the variable dilution system. > They have a very high capacity for a short time blast of PM such as we get > in stoves during ignition. For a 150 mg max unit we can increase the > dilution to perhaps 100 or 200 then reduce it to 4 or 5. The combination of > a TEOM and the current setup means we can decrease the dilution by a factor > of 6.66 which is a big improvement in precision.**** > > ** ** > > I say your new large filter at the GERES lab and it looks really good. It > looks off-the-shelf with the PM10 impactor. Where do we get one?**** > > ** ** > > Thanks > Crispin**** > > ** ** > > *From:* Stoves [mailto:[email protected]] *On > Behalf Of *Dean Still > *Sent:* Tuesday, August 27, 2013 1:13 PM > *To:* Discussion of biomass cooking stoves > *Subject:* Re: [Stoves] A photo of a lab test from Ulaanbaatar**** > > ** ** > > 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/ > > **** > > ** ** > > _______________________________________________ > 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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