An innovative activity-oriented direct reaction screening method for reduction of detailed chemical kinetic mechanism

An activity-oriented direct reaction screening (AODRS) method is proposed to simplify the reduction of detailed chemical kinetic mechanism. This method requires only four parameters (c_GISS, c_LO, c_T, and c_RIT) to generate a skeletal mechanism. Extensive experience or expertise is not necessary for identifying important species, as these species are determined locally and dynamically based on their absolute molar converting fluxes. c_GISS is used to dynamically identify and construct the global important species scope, while c_LO is used to dynamically identify the local target species. Reactions with higher contribution coefficients than c_T and having species all belonging to the global important species scope are classified as locally important. Then locally important reactions with higher importance tendency than c_RIT are identified as global important reactions. To validate the proposed method, detailed mechanisms for NH₃CH₄ and n-heptane are reduced stepwise. As c_GISS and c_LO increase while c_T and c_RIT decrease, the relative errors in ignition delay time, laminar flame speed, and species concentrations generally decrease. With the criterion of 5 % maximum relative error in ignition delay time, a skeletal mechanism achieving reductions of 62 % in reactions and 59 % in species is obtained for the NH₃CH₄. Meanwhile, a skeletal mechanism for n-heptane within 10 % relative error in ignition delay time achieves reductions of 67 % in reactions and 58 % in species. Additionally, ignition delay time, laminar flame speed, and species concentrations are extensively evaluated. Results indicate that, with a comparable number of reactions, skeletal mechanisms generated by AODRS exhibit better agreement with detailed mechanisms compared to skeletal mechanisms generated by DRGEPSA and DRGEP methods. Finally, the recommended value ranges for c_GISS, c_LO, c_T, and c_RIT have been further constrained.