Modelling Soot Formation: Model of Particle Formation

This article reports on detailed models of soot particle formation in combustion. First, we present the polycyclic aromatic hydrocarbon-primary particle (PAH-PP) model where soot particles are described by primary particles which are made up of PAHs. The model describes the formation, growth and oxidation of soot in laminar premixed ethylene flames. The connectivity between primary particles is stored to calculate the rounding of soot particles due to surface growth and condensation. We then show that a model intermolecular potential based on the simple Lennard-Jones potential supports the physical binding of PAHs as a viable mechanism for soot formation. We subsequently present the kinetic Monte Carlo-aromatic site (KMC-ARS) model which describes the structure and growth of planar PAHs. The PAH processes are represented as jump processes, and the energetics and kinetics were determined by quantum chemistry calculations. Lastly, we use molecular dynamics with a new potential specifically developed for PAH interaction and the combined PAH-PP/KMC-ARS model to show that pyrene dimerisation is unlikely to be the critical soot formation step at flame temperatures of about 1500–2000 K.