Stochastic and network analysis of polycyclic aromatic growth in a coflow diffusion flame

Area of Science:

• Combustion chemistry
• Nanoparticle formation
• Chemical kinetics

Background:

• Soot nanoparticle formation is critical for predicting combustion efficiency and emissions.
• Aromatic precursors significantly influence nanoparticle properties, regardless of clustering.
• Understanding gas phase variations impacting precursor formation is essential.

Purpose of the Study:

• To investigate the spatial evolution and formation pathways of polycyclic aromatic compounds (PACs).
• To analyze the influence of flame conditions on PAC molecular structures and properties.
• To identify key reaction networks governing PAC growth and oxygenation.

Main Methods:

• Utilized experimental data from a coflow Jet A-1 surrogate diffusion flame.
• Employed SNapS2 kinetic Monte Carlo software for simulating PAC chemical evolution.
• Applied graph theory and network analysis to study the reaction network.

Main Results:

• PAC growth is concentrated in regions of high acetylene concentration.
• PACs exhibit diverse chemical properties, including aliphatic chains and various ring structures.
• Growth is immediate near flame wings but delayed along inner streamlines until high radical concentrations are encountered.
• Stable PAC structures act as hubs for growth and oxygen addition reactions.

Conclusions:

• PAC properties are determined by their location within the flame and associated reaction pathways.
• Oxygenated PAC structures are significant, particularly along inner streamlines.
• Network analysis reveals stable PAC structures that dictate growth and oxygenation pathways.