Hydrogen Effect on Soot Formation in Ethylene-Syngas Mixture Opposed Jet Diffusion Flame in Non-conventional Combustion Regime

Abstract

The influence of the addition of hydrogen on the formation of soot in an ethylene-gas/air mixture of a counter-current laminar diffusion flame in the flameless regime and at atmospheric pressure has been studied. A detailed gas phase reaction mechanism, including aromatic chemistry up to four cycles and complex thermal and transport properties, was used. The soot is modeled by the moments method. The interactions between soot and gas phase chemistry have been taken into account. Losses by thermal radiation (from CO₂, CO, H₂O from CH₄ and soot) modeled by a thin body. Adding hydrogen to the fuel eliminates the formation of soot. The calculations further suggest that the effect of the addition of hydrogen on soot formation is due to the absence of the concentration of hydrogen atoms in the surface growth regions of soot (stagnation plane) and at a higher concentration of molecular hydrogen in the flame zone. It also reduces the concentrations of C₃H₃, C₆H₆ as well as PAHs (for example, pyrene) which all suppress the process of soot formation.