1. Combustion Seminar Wildacres 2012 1

2. Combustion 2

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6. 6 Combustion reactions During complete combustion, the following reactions take place: C + O 2 = CO 2 2H 2 + O 2 =2H 2 O During incomplete combustion, we get: 2C + O 2 =2CO All of these reactions are exothermic. They result in a conversion of chemical energy into heat: 1kg C + 2.67kg O 2 = 3.67kg CO 2 + 32,000 BTU or 9.6 kWh 1kg C + 1.33kg O 2 = 2.33kg CO + 9,500 BTU or 2.9 kWh 1kg CO + 0.57kg O 2 = 1.57kg CO 2 + 9,500 BTU or 2.9 kWh 1kg H 2 + 8.0kg O 2 = 9.0kg H 2 O + 135,000 BTU or 40.5 kWh

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10. EMISSIONS AND TESTING 10

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12. 12 PM2.5 particulate matter smaller than 2.5 microns A blood corpuscle is 6 microns, so these particles are in the biologically active size range PM – Particulates (particulate matter)

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14. 14 Soot Requires a flame to form Carbon (“lamp black”) Black smoke Very lightweight. You can have visible smoke, yet a fairly low PM number Test filters are black, but have no smell

15. 15 Tar Requires absence of flame (smoldering) to form 90% of particles are smaller than 1 micron (= 0.001 mm) Blue smoke -- The wavelength of blue light is 0.5 microns Contains PAH’s – polycyclic aromatic hydrocarbons – a major health concern, can be carcinogenic Measurable with a filter, but requires cooling first to condense all the tar, by diluting with air (dilution tunnel) Heavy, high PM numbers Test filters have a very distinctive “creosote” smell. If there is no soot, the filter can be yellow, like a cigarette filter

16. 16 Smoldering combustion = Low burn rate = tar = creosote Masonry heaters are never operated at low burn rates Therefore, they emit little or no tar Any visible smoke is soot, or water (white smoke), provided you do a top-down burn. If you cool the chimney on a masonry heater too much, you can get water condensation in the chimney. However, it is impossible to get creosote, because there is no tar in the smoke. If you see black liquid, it is water and soot. It is not impossible to make tar, but you really have to try.

17. 17 Clean burning = no visible smoke, or visible white smoke (water) Even cheap non-EPA stoves can be clean if you burn them fast enough, with unrestricted air and a firebrick firebox. Usually the problem is that you will overheat the house Heat storage is what makes a masonry heater unique This allows fast burn rate + low heat output

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