A COMPUTATIONAL STUDY OF SOOTING LIMITS IN LAMINAR PREMIXED FLAMES OF ETHANE, ETHYLENE, AND ACETYLENE

The onset of sooting in laminar premixed flames was examined computationally. Three series of atmospheric fuel-oxygen-nitrogen flames of ethane, ethylene, and acetylene were simulated using a detailed chemical kinetic model of soot particle nucleation and growth. It was found that the critical equivalence ratios for soot appearance, both the absolute values and temperature dependencies, can be predicted fairly close to the experimental observations, even when no reactions for the oxidation of aromatics by hydroxyl are included in the mechanism. The analysis of the computational results strongly suggests that the appearance of soot is controlled by two factors, concentration of acetylene and growth of polycyclic aromatics, and the latter is limited by the rise in flame temperature towards the end of the main reaction zone. The present results and conclusions are in agreement with the principal findings of previous modeling studies.