Insight into fuel isomeric effects on laminar flame propagation of pentanones

Abstract

Laminar flame propagation was investigated for pentanone isomers/air mixtures (3-pentanone, 2-pentanone and 3-methyl-2-butanone) in a high-pressure constant-volume cylindrical combustion vessel at 393–423 K, 1–10 atm and equivalence ratios of 0.6–1.5, and in a heat flux burner at 393 K, 1 atm and equivalence ratios of 0.6–1.5. Two kinds of methods generally show good agreement, both of which indicate that the laminar burning velocity increases in the order of 3-methyl-2-butanone, 2-pentanone and 3-pentanone. A kinetic model of pentanone isomers was developed and validated against experimental data in this work and in literature. Modeling analysis was performed to provide insight into the flame chemistry of the three pentanone isomers. H-abstraction reactions are concluded to dominate fuel consumption, and further decomposition of fuel radicals eventually produces fuel-specific small radicals. The differences in radical pools are concluded to be responsible for the observed fuel isomeric effects on laminar burning velocity. Among the three pentanone isomers, 3-pentanone tends to produce ethyl and does not prefer to produce methyl and allyl in flames, thus it has the highest reactivity and fastest laminar flame propagation. On the contrary, 3-methyl-2-butanone tends to produce allyl and methyl instead of ethyl, and consequently has the lowest reactivity and slowest laminar flame propagation.