A previously derived 12-step, 16-species augmented reduced mechanism (ARM),
based on GRI-Mech 1.2, was shown to be comprehensive for methane oxidation
at the levels of global response as well as detailed flame structure. The
present study updates and extends this effort by basing the reduction an th
e recently released GRI-Mech 3.0 and by including the description of NOx fo
rmation. Specifically, by assuming all the nitrogen-containing species (exc
ept N-2) are in steady state, an equivalent 12-step ARM was developed. Subs
equently, a 14-step and a 15-step ARMs were derived to account for NO forma
tion. The 14-step ARM is basically the 12-step ARM plus two more steps that
respectively describe the thermal, prompt, and nitrous oxide mechanisms, a
nd the prompt mechanism Further inclusion of NH3-related reactions yielded
the 15-step ARM. A 17-step ARM was also developed to account for the additi
onal emissions of nitrogen dioxide and nitrous oxide. It is shown that, by
including such optimum numbers of non-steady-state intermediates for the va
rious mechanisms the present ARMs exhibit good to excellent performance in
predicting a wide range of combustion phenomena under extensive thermodynam
ic parametric variations. (C) 2001 by The Combustion Institute.