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

2 Combustion Theory
In conclusion, the best performance could be obtained with the combination
“n-Decane (Princeton) + NO x (Li)”. The results were reliable and convergence
was very good. The combination “n-Decane (Princeton) + NO x (Leeds)”
showed a number of problems concerning numerical stability. On the other
hand, the combination “n-Decane (Aachen) + NO x (Li)” had similar problems
and slightly inconsistent results in regard to laminar flame speed. The combination
“n-Decane (Aachen) + NO x (Leeds)” exhibited insufficient convergence
for CH 4 , C 2 H 6 , and C 10 H 22 flames. Here, it is very likely that fuel and NO x
chemistry interfere negatively, producing a stiff system of equations [298].
Validation of NO x Values Against Experimental Measurements
As illustrated in Figure 2.14, the NO x formation characteristics of the combination
“n-Decane (Princeton) + NO x (Li)” were finally tested against the experimental
measurements of Egolfopoulos [118]. A counterflow configuration
was employed with a jet of nitrogen (N 2 ) counter-flowing against premixed
n-decane/air, thus quenching the flame. Lean, stoichiometric, and fuel-rich
120
ppm
100
Experiments
(Egolfopoulos, 2009)
Simulation
~
NOx concentration XNOx
80
60
40
20
0
0.0 0.2 0.4 0.6 0.8 1.0 cm
Distance from bottom burner x
Figure 2.14: Experimental and Numerical Data on Nitrogen Oxide Formation for Counterflow
Configuration. The comparison shows data for an equivalence ratio of
φ= 1.0. The experimental results are taken from Egolfopoulos [118].
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