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Download fileA Theoretical Multiscale Approach to Study the Initial Steps Involved in the Chemical Reactivity of Soot Precursors
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posted on 09.10.2019, 01:03 authored by Michel Keller, Theodorus de Bruin, Mickaël Matrat, André Nicolle, Laurent CatoireIn
the present study, bond formation reactions between soot precursors
and their role in the soot inception process are investigated. The
soot precursors were generated in macroscopic detailed gas-phase kinetic
calculations and according to certain criteria introduced in simulation
boxes to model bond formation between soot precursor molecules with
reactive force field molecular dynamics modeling. The impacts of temperature,
fuel mixture, and equivalence ratio have been investigated on the
rate and structure of the newly formed molecules. The resulting structures
compare well to previously reported experimental results. Furthermore,
the bond formation rate between PAHs is found to be linearly correlated
with the temperature at which the PAH precursors are generated, while
fuel and equivalence ratio do not have a direct impact on the reaction
rate. The generated growth structures are lumped in (1) directly linked,
(2) aliphatically linked, and (3) pericondensed polycyclic hydrocarbons.
It is found that the amount of aliphatically linked PAH increases
with the amount of aliphatic content of the fuel mixture. Finally,
a reaction scheme is presented displaying the most representative
reaction pathways to form growth structures in each lumping class
and their eventual interconversion. The present workthat applies
a combined approach of macroscopic gas-phase kinetic calculations
and atomistic reactive force field simulationsoffers a good
alternative to obtain structural differences of nascent soot for a
broad range of thermodynamic conditions and detailed reaction mechanisms
for the soot inception process.