Dear Frank I am trying to limit the message length so if someone misses the point, refer to the original longer text. Here goes: >...Then the DRX reading >>of 2.5 is multiplied by 11 giving 27.5 mg/m^3. >The turbidity reading is somehow converted to weight?
The Dusttrak reports in mg per cubic metre based on some assumptions (which you can tweak) about their density. >And do you have an idea of the range of particle diameters of the PM? It is a light scattering instrument so it can measure from PM0.1 to something quite large. Normally coal and wood fires with no fan have a profile that is almost entirely less than PM 1.0. >What I am thinking is >if the particles you are looking at is greater than 0.7 um they can be >collected on a Whatman GF/F filter and carbon determined in a Leco >(large boat) C/N analyzer. There is a 37mm HEPA filter (you can get quick change cartridges for continuous collection) in the instrument. This can be weighed and use to correct the light scattering instrument. >We would then know the real energy loss in the PM. Nearly nothing. >>Let's say it is 8 kg of gases per kg of >>fuel missing from the fire (remember the ash does not burn off). >This because the carbon in the wood converts to CO2 during combustion >using both the 50% oxygen in the wood and from the 20% in the outside >air and hydrogen to H2O increasing the weight approx. 8 times (?) Yes. The volume of the resulting gases. In our case we are calculating the volume of steam produced by evaporating the moisture as well as resulting from combustion of H2. I am very pleased with that actually. >>Suppose it is 250%. Lambda is excess air plus 100% so Lambda is 3.5. >Where does this + 100% come from? Air demand consists of air you needed (100%) and air you didn't need, called "Excess Air". So the total air needed is EA + 100%. If EA is expressed as a factor and not %, it is EA+1. >>That is >>28/1.18 = 23.73 cubic metres, which is the same as 23.73 litres of gas for >>each gram burned. >Going slow here..... : ) No problem... >The 1.18 value is converting grams gas mixture to ~mole of the mix? Air weighs about 1.18 kg per cubic metre. It converts the kg into cubic metres as the PM was expressed in mg/m^3. >Whats important here is to keep the ratio of PM/MJ at its best (lowest) >value while 'working'. You need the heat. Space heating is about keeping warm. The PM emitted while doing so is the interesting part. If you want a 'general number' that can be applied to different buildings, PM/MJ is the logical answer. If you get PM/kg the first thing you have to do is work out how many kg you need to burn to get the MJ you need as the /kg number has no meaning on its own. As the fuels are all different, it is difficult to compare them meaningfully. Giving the PM/MJ gives the emission directly, per useable amount of heat. >The time needed for the stove to burn to do the >job is the thermal efficiency (as I think about it). It also matter what the thermal efficiency of the stove is, and the thermal performance of the build. Careful not to confuse the two. >I guess these stack measurements and calculations need be done (during >working) if we want to compare TE for stoves in a catalog to be able to >pick one. Agreed. >We still need to (1) state the fuel type/quality being used, Not if you give PM/MJ. That means it is not necessary, just nice to have. You do need the PM/MJ figure to make any meaningful calculation of what the emissions from heating a particular building will be. >perhaps (2) have a fan of a certain power to blow air over a stove >(standardize for heating a room) and (3) water boiling or (4) something >frying (to simulate cooking). You are mixing two different tasks. The heating of the building is a measure of the performance of the building, not particularly the stove. If the burn rate of the stove is known, the fuel heat content, and the thermal efficiency, you know the deliverable heat. What the building does with it is another matter completely. If the building is insulated, it will reduce the heat demand. The PM produced will drop in consequence because of a better building. The other thing, boiling, is a cooking task. That is a test of the thermal efficiency for cooking. Usually space heating stoves have a low cooking efficiency and no one cares. >I suggest we should work the stove for hours >when collecting data for comparison. Cooking tests the stove. Room temperature tests the building. >You are using coal from one coal mine? without more drying? We are doomed to use what people have. They have easy access to Nalaikh coal mine wet lignite (20-25% moisture). They also can get a younger coal from Baganuur which is quite high in oils/hydrocarbons. It takes a longer flame to burn completely. The best so far was a downdraft stove v.5.3. It has extraordinarily low PM. The GTZ-7 stove has extraordinarily low CO. Now to cross-pollinate them... I want to get a 98% reduction across the board as determined within the limits of the accuracy of the instruments. Regards Crispin _______________________________________________ Stoves mailing list [email protected] http://listserv.repp.org/mailman/listinfo/stoves_listserv.repp.org http://stoves.bioenergylists.org http://info.bioenergylists.org
