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A computational study of ethylene–air sooting flames: Effects of large polycyclic aromatic hydrocarbons

Publication Type : Journal Article

Publisher : Combustion and Flame .

Source : Combustion and Flame, Volume 163, p.427 - 436 (2016)

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Keywords : Laminar flames, Method of moments, Polycyclic aromatic hydrocarbon, Reduced mechanism, Soot model

Campus : Coimbatore

School : School of Engineering

Department : Mechanical Engineering

Year : 2016

Abstract : An updated reduced gas-phase kinetic mechanism was developed and integrated with aerosol models to predict soot formation characteristics in ethylene nonpremixed and premixed flames. A primary objective is to investigate the sensitivity of the soot formation to various chemical pathways for large polycyclic aromatic hydrocarbons (PAH). The gas-phase chemical mechanism adopted the KAUST-Aramco PAH Mech 1.0, which utilized the AramcoMech 1.3 for gas-phase reactions validated for up to C2 fuels. In addition, PAH species up to coronene (C24H12 or A7) were included to describe the detailed formation pathways of soot precursors. In this study, the detailed chemical mechanism was reduced from 397 to 99 species using directed relation graph with expert knowledge (DRG-X) and sensitivity analysis. The method of moments with interpolative closure (MOMIC) was employed for the soot aerosol model. Counterflow nonpremixed flames at low strain rate sooting conditions were considered, for which the sensitivity of soot formation characteristics to different nucleation pathways were investigated. Premixed flame experiment data at different equivalence ratios were also used for validation. The findings show that higher PAH concentrations result in a higher soot nucleation rate, and that the total soot volume and average size of the particles are predicted in good agreement with experimental results. Subsequently, the effects of different pathways, with respect to pyrene- or coronene-based nucleation models, on the net soot formation rate were analyzed. It was found that the nucleation processes (i.e., soot inception) are sensitive to the choice of PAH precursors, and consideration of higher PAH species beyond pyrene is critical for accurate prediction of the overall soot formation.

Cite this Research Publication : Prabhu S., Arias, P. G., Lee, B. Jik, Im, H. G., Wang, Y., Gao, Y., Park, S., S. Sarathy, M., Lu, T., and Chung, S. Ho, “A computational study of ethylene–air sooting flames: Effects of large polycyclic aromatic hydrocarbons”, Combustion and Flame, vol. 163, pp. 427 - 436, 2016.

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