Development of a Fully Reversible PAH Clustering Model

Abstract

Physical clustering of Polycyclic Aromatic Hydrocarbon (PAH) molecules is subject to many studies as a part of understanding the complex clustering behavior and formation of carbon nanoparticles, such as soot and carbon black. A new fully reversible PAH clustering (FRPC) model is introduced to account for the full reversibility of PAH inception and molecular adsorption. Instead of assessing the performance of the new FRPC in a flame simulation as is typically done, a simplified system is utilized such that PAH clustering can be isolated from all other particle processes. The chosen simplified system consists of a 0D homogeneous reactor of PAHs at certain temperatures and has previously been investigated using molecular dynamics. The results from the FRPC model display excellent performance when compared to the molecular dynamic results. It is found that reversible rates play a significant role for smaller PAHs and at higher temperatures where the conditions are closer to an equilibrium between the gas-phase and condensed-phase PAHs. It is demonstrated that efficiency-based models are ill-suited to model PAH clustering due to the lack of explicitly modeling the reverse rates of clustering. The newly developed FRPC model represents the first step in a piece-wise development of a carbon nanoparticle formation model. ▪