Numerical investigation on the influence of carbonaceous particles on the ignition behavior of methane/air mixtures

The ignition behavior of an enclosed stoichiometric methane/air mixture in the presence of carbonaceous particles was studied by means of a one-dimensional numerical model composed of the reactive Navier-Stokes equations for the gas phase and the reactive Euler equations for the particle phase. Both phases are considered to be continuously distributed. For the homogeneous gas-phase reactions, a detailed kinetic model has been chosen, whereas the gas/particle reactions are described by global heterogeneous reactions. The system of equations is treated by TVD flux difference splitting schemes on a moving adaptive grid solved by an implicit integrator. Simulation results for a particle volume fraction of 7.9 x 10(-5) demonstrate that the heat-absorbing particles cause an increase in ignition delay time, Moreover, the model used predicts that the gas/particle reactions increase the CO molar fraction in the burned gas region, while the CO2 fraction is lower than in the pure gas case. For the case studied, the particles only weakly influence the shapes of pressure, temperature, and HO2 molar fraction.