Rate-Controlled Constrained-Equilibrium Calculations of Methane–Oxygen Kinetics Using Reduced Chemistry

According to the underlying concept of the rate-controlled constrained-equilibrium (RCCE) method, the relaxation of a complex reacting system towards the final equilibrium state is governed by a set of active and passive constraints imposed by the internal dynamics of the system, which is considerably smaller in dimension than the original sys tem. A set of 12 constraints, able to accurately model the dynamic evolution of the methane oxidation over a wide range of initial temperatures and pressures is proposed. Based on rational analysis of the important rate-limiting steps a further reduced set is obtained, which when is used in conjunction with RCCE is able to give excellent predictions for dynamic evolution of the system at low temperatures at different pressures. Some salient features of RCCE are explored and the RCCE method is proposed as a physics-based, rational alternative approach for the conventional detailed kinetics. The kinetic scheme involves only C1 chemistry and comprises 132 reactions along with 29 species without nitrogen chemistry.