On the Formation of Nitrogen Oxides During the Combustion of ...

2.3 Kinetic Modeling
a flame. The GRI 3.0 mechanism (Fig. 2.7) was published by Smith et al. [408],
GRI 2.11 by Bowman et al. [52], and the Leeds methane mechanism by Hughes
et al. [187]. As illustrated in Figure 2.8, the influence of the fuel mechanism is
much stronger than the difference between the NO x kinetics of Li and Williams
[250] and the Leeds NO x mechanism. The results are similar for combinations
with either the Princeton or the Aachen n-decane mechanism [298].
Prompt
Apart from the reaction of N 2 and CH (Eq. (2.10)), the Leeds mechanism [187]
additionally includes reactions of N 2 with C and CH 2 radicals as the initial reactions
of prompt NO formation. Figure 2.9 compares the reactivity of the
three radicals. The activation energy of the nitrogen reaction with CH is by
far the lowest with E a = 7.508×10 4 J mol −1 , thus making it the most reactive.
The activation energy of the reaction with C and CH 2 is E a = 1.879×10 5 and
3.096×10 5 J mol −1 , respectively [298]. Consequently, the reaction of N 2 and
CH is the most important of the prompt NO mechanism.
4.0 x 10 10
cm 3 mol −1 s −1
N 2 + C N + CH
N 2 + CH N + HCN
N 2 + CH 2 NH + HCN
Rate coefficient k
3.0 x 10 10
2.0 x 10 10
1.0 x 10 10
0.0 x 10 10
500 1000 1500 2000 2500 K
Temperature T
Figure 2.9: Reactivity of the Initial Reactions of the Prompt NO Mechanism.
45