A study on the coagulation of polycyclic aromatic hydrocarbon clusters to determine their collision efficiency


This paper presents a theoretical study on the physical interaction between polycyclic aromatic hydrocarbons (PAHs) and their clusters of different sizes in laminar premixed flames. Two models are employed for this study: a detailed PAH growth model, referred to as the kinetic Monte Carlo—aromatic site (KMCARS) model [Raj et al., Combust. Flame 156 (2009) 896–913]; and a multivariate PAH population balance model, referred to as the PAH—primary particle (PAH-PP) model. Both the models are solved by kinetic Monte Carlo methods. PAH mass spectra are generated using the PAH-PP model, and compared to the experimentally observed spectra for a laminar premixed ethylene flame. The position of the maxima of PAH dimers in the spectra and their concentrations are found to depend strongly on the collision effi- ciency of PAH coagulation. The variation in the collision efficiency with various flame and PAH parameters is studied to determine the factors on which it may depend. A correlation for the collision efficiency is proposed by comparing the computed and the observed spectra for an ethylene flame. With this correlation, a good agreement between the computed and the observed spectra for a number of laminar premixed ethylene flames is found.

Keywords: PAH, soot, soot formation,

Associated Projects: Numerics and Particle Processes

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