posted on 2019-12-19, 17:38authored byQuan-De Wang, Yanjin Sun, Henry J. Curran
Emission of nitrogen oxides (NOx) are one of the major environmental concerns arising from
the combustion of syngas. Strategies to reduce emission and improve
the efficiency of syngas combustion can be developed using computational
fluid dynamic simulations to design cleaner and more efficient combustors.
Toward this end, an accurate and efficient chemical kinetic mechanism
that can describe the combustion chemistry of syngas with NOx under engine-relevant conditions is critical. In
this work, a comprehensive survey of detailed mechanisms available
in the literature for the syngas/NOx combustion
reaction system is first conducted. A systematic and comparative chemical
kinetic analysis of five detailed mechanisms is performed based on
the reaction pathway and sensitivity analyses to identify the key
reactions of the nitrogen species for a wide range of mixtures including
the formation of NOx during syngas combustion
and ignition of NH3, H2/N2O, and
H2/NO2 mixtures. Comparisons of the reaction
pathways from different detailed mechanisms indicate that the detailed
chemistry is controlled by a small set of reactions and species. Recent
high-level theoretical studies on HONO and HNO2 chemistry
including previously neglected important reactions are updated. The
rate constants for HNO + O2 = NO + HȮ2 are calculated using ab initio calculations in this work. An efficient
high-fidelity skeletal mechanism consisting of 27 species and 130
reactions is developed based on a combination of the directed relation
graph with the error propagation method and the simplified iterative
screening and structure analysis method. Compared to the detailed
mechanisms, the skeletal mechanism retains the major species and reactions
for the syngas/NOx system and is validated
against the typical experimental data, resulting in a very good performance.