Reactive molecular dynamics simulations of soot formation in acetylene combustion with hydrogen addition

Abstract

Soot emission from combustion devices not only reduces energy efficiency but also poses a serious risk to global warming and human health. The reactive molecular dynamics simulation is used to study the soot formation process of acetylene as the initial fuel and oxygen as the oxidant, and the chemical effect of hydrogen addition on the soot formation of acetylene combustion is deeply analyzed in this paper. The study found that: in addition to the hydrogen abstraction acetylene addition mechanism, it is also an important path that the long carbon chain aliphatic hydrocarbon with branched chain form polycyclic aromatic hydrocarbons by condensation after continuous dehydrogenation; the chemical effect of hydrogen addition linearly reduces the number of carbon in soot particles, the bond angle energy and torsion angle energy of soot, resulting in a smaller soot particle size and a sparse soot morphology. The shape of the soot gradually changes from a dense spindle-shaped structure to a sparse planar structure; the main chemical effect of hydrogen doping inhibits the dehydrogenation reaction of aliphatic hydrocarbons and aromatic hydrocarbons mainly through H + CaHb↔CaHb−1 + H2, thereby inhibiting the formation of polycyclic aromatic hydrocarbons and soot nucleation, ultimately leading to a reduction in soot production.