Effect of Hydrogen Addition on Soot Formation and Emission in Acetylene Laminar Diffusion Flame

[Image: see text] Hydrogen (H(2)) has been regarded as a highly competitive alternative fuel that does not produce CO(2) and soot during combustion. There are few studies of cofiring H(2) with hydrocarbons. Meanwhile, the effect of hydrogen addition on soot formation and emission is questionable. In this study, the effect of H(2) addition with varying ratios (between 0 and 50% by molar fraction while the remainder is nitrogen) on soot formation in acetylene (50% by molar fraction) laminar diffusion flames was experimentally and numerically investigated. Results show that with H(2) addition, the flame height increases and the temperature decreases. The total soot emission and the primary particle size both increase with H(2) addition. The addition of H(2) promotes soot formation. In addition, the soot oxidation is weakened due to the lower flame temperature. Chemical kinetic analysis shows that the concentrations of A1, H, and H(2)O increase with H(2) addition, which is consistent with the experimental results. According to the HACA reaction, the increase of the molar fraction of A1 and H radicals could promote PAH growth and soot formation.