Effects of the nitrous oxide decomposition reaction on soot precursors in nitrous oxide/ethylene diffusion flames

Abstract

This study investigated the effects of oxygen enrichment and the resulting heat release generated by the N2O-decomposition reaction on the soot formation of C2H4/N2O diffusion flames. The effects of N2O decomposition on flame structure and pollutant emission were examined through a numerical study with the USM mechanism. The aforementioned simulation was performed to analyze the effects of C2H4/N2O and C2H4/N2/0.5 O2 on diffusion flames. The N2O-decomposition effect was examined partly to explore the effect of heat release on the overall temperature, combustion characteristics, and alteration of chemical reaction pathways and especially to predict soot formation by observing the concentration of precursor C2 to C4 species. To eliminate the thermal effect of the N2O-decomposition reaction on soot formation, a C2H4/N2/0.5O2 mixture was preheated to a compensated temperature of 1800 K, which was inherited from the exothermic release of heat in the N2O-decomposition reaction. Furthermore, the concentration of C6H6 formation was lower for the preheated C2H4/N2/0.5 O2 flame than for the C2H4/N2O flame. Compared with the C2H4/N2O case, the mole fractions of key soot precursors such as propargyl, benzene, and pyrene were significantly lower in the preheated C2H4/N2/0.5 O2 case, which led to enhanced soot inception.