Unraveling chemical structure of laminar premixed tetralin flames at low pressure with photoionization mass spectrometry and kinetic modeling

This work reports an investigation on laminar premixed flames of tetralin at 30 Torr and equivalence ratios of 0.7 and 1.7. Measurements of the chemical structure including identification and mole fraction measurements of free radicals, isomers, and polycyclic aromatic hydrocarbons (PAHs) were performed using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). A kinetic model with 296 species and 1 577 reactions was developed and validated against the flame chemical structure data measured in this work. Modeling analysis reveals the key reaction pathways in tetralin decomposition and PAHs formation. The H-atom abstraction reactions by H, O, and OH are found to control the consumption of tetralin in the lean flame, while those by H play the dominant role in the rich flame. Indene and naphthalene have very high concentration levels in the rich tetralin flame due to the existence of direct formation pathways from the decomposition of tetralin. The two bicyclic PAHs and their radicals play significant roles in the PAHs growth process of tetralin combustion, which results in the high sooting tendency of tetralin compared to those of alkylbenzenes with smaller or same carbon atom numbers.