Sw. Cho et S. Niksa, ELEMENTARY REACTION MODELS AND CORRELATIONS FOR BURNING VELOCITIES OFMULTICOMPONENT ORGANIC FUEL MIXTURES, Combustion and flame, 101(4), 1995, pp. 411-427
This computational study uses elementary reaction mechanisms to interp
ret the trends in a database of burning velocities for multicomponent
organic fuel mixtures derived from coal. These mixtures contain CO, H-
2, CH4, C2H2, oils, and, in some cases, appreciable amounts of C2H4, C
2H6, C3H6, and C3H8 The database represents fuel equivalence ratios fr
om 0.5 to 1.5, two unburned gas temperatures, and two diluent: O-2 rat
ios. Predicted burning velocities are based on a one-dimensional lamin
ar flame code with the Miller-Bowman mechanism without nitrogen conver
sion chemistry or oxidative pyrolysis of any higher hydrocarbons. The
initial amounts of oils and higher hydrocarbons are expressed as addit
ional amounts of C2H4 and C2H6 and reduced levels of H-2. Burning velo
cities of multicomponent fuel mixtures at high temperatures can be int
erpreted with only oxyhydrogen and C-1/C-2 chemistry without any fuel
decomposition steps for the higher hydrocarbons. This approach rationa
lizes the trends due to higher extents of secondary volatiles pyrolysi
s, which means increasing CO and H-2 levels and diminishing hydrocarbo
n Levels in the fuel mixtures. It also rationalizes the variations wit
h coals of higher rank, which means diminishing CO levels and H-2 and
hydrocarbon levels that pass through maxima. Predictions from the elem
entary reaction mechanism are quantiatively accurate for nearly all le
an mixtures, but discrepancies are substantial for rich mixtures, espe
cially those with abundant CO and H-2. Systematic overpredictions for
rich mixtures are probably due to defects in steps for the attack of C
-1 or C-2 species by O-2 or H atoms.