Effect of Hydrogen Addition on the Sooting Tendency of 1,3-Butadiene Premixed Flames

Abstract

Mole fractions and formation-depletion pathways of the first aromatic ring and its precursors, acetylene and propargyl radical as well as those of naphthalene are numerically investigated during the co-combustion of 1,3-butadiene/H₂ mixtures in low pressure premixed laminar flames conditions. The molar fraction of H₂ in the mixture is varied from 0 to 60% by adding 10% of hydrogen to the neat butadiene flame and by keeping the inert mole fraction (argon) and the equivalence ratio constants. The effect of hydrogen is investigated by using a modified Chemkin II version and by differentiating its chemical effect from its thermal and dilution effects. The obtained results indicate that the butadiene/H₂ oxidation process is controlled by the synergism between hydrogen dilution and chemical effects. Regardless of the hydrogen amount added to the fuel mixture, two routes are evolved in the benzene formation process, the direct C₄ + C₂ route and the indirect C₃ route, evolving fulvene as an intermediate species. Besides, the collected data reveal that hydrogen doping induces a noticeable decrease in the concentrations of all the studied species inferring that the hydrogen blended fuels are less prolific in soot formation than the neat 1,3-butadiene fuel. The observed decrease is dependent on the hydrogen initial concentration in the fuel mixture as well as on the nature of its effect.