Experimental and modeling investigation on premixed ethylbenzene flames at low pressure

Three premixed ethylbenzene/O2/Ar flames with equivalence ratio (φ) of 0.75, 1.00, 1.79 were studied at low pressure (4.0 kPa) to represent the lean, stoichiometric, and rich ethylbenzene flames. Flame species were identified using synchrotron vacuum ultraviolet photoionization mass spectrometry, and their mole fractions were evaluated. The maximum mole fractions of hydrocarbon intermediates were observed to increase with φ increasing. A kinetic model including 176 species and 804 reactions was developed with detailed submechanisms of ethylbenzene and toluene. The validation of the model was made by simulating the measured mole fractions of flame species, showing good agreement in reproducing the mole fractions of most observed species. Furthermore, rate of production analysis reveals the main formation and consumption channels of some key hydrocarbon intermediates involved in ethylbenzene decomposition and PAHs formation. The main reaction channels of these species in the rich flame have salient differences with those in the lean flame, indicating the different chemistry between the pyrolysis dominated and oxidation dominated circumstance, while the chemistry in the stoichiometric flame is more similar to that in the lean flame. Furthermore, reactions involving phenyl and benzyl are concluded to be critical for PAHs formation in the rich ethylbenzene flame.