Study on Products from Fuel-rich Methane Combustion near Sooting Limit Temperature Region and Importance of Methyl Radicals for the Formation of First Aromatic Rings. Issue 4 (12th March 2022)

• Record Type: Journal Article
• Authors: Kanayama, Keisuke; Dubey, Ajit K.; Tezuka, Takuya; Hasegawa, Susumu; Nakamura, Hisashi; Maruta, Kaoru
• Is Part Of: Combustion science and technology. Volume 194:Issue 4(2022)
• Page Start: 832
• Page End: 849
• Publication Date: 2022-03-12
• Subjects: Microcombustion -- natural gas -- reformed gas -- polycyclic aromatic hydrocarbons (PAHs) -- soot precursors; Combustion -- Periodicals; Combustion engineering -- Periodicals; 541.36105
• DOI: 10.1080/00102202.2020.1787394
• Languages: English
• ISSNs: 0010-2202

Abstract

ABSTRACT: Productions of mono-/di-cyclic aromatic hydrocarbons as well as smaller stable species from extremely fuel-rich CH4 /air mixtures (equivalence ratio of 1.7–6.0 and fuel-to-mixture ratio of 15–38 mol.%) near sooting limit in terms of temperature, were investigated using a micro flow reactor with a controlled temperature profile at maximum wall temperature of 1300 K. Species measurements of O2, H2, CO, CO2, CH4, C2 H2, C2 H4, C2 H6, benzene, toluene, styrene and naphthalene were performed with GC and GC/MS analysis. One-dimensional computations were also conducted with several detailed chemical kinetics. Most of the mechanisms comparably well predicted the smaller species except C2 H2 (acetylene), which was overestimated by all the mechanism especially at moderate equivalence ratio ( Ø ≤ 3.0). There were large discrepancies between measured and computed mole fractions of benzene and naphthalene at high equivalence ratio ( Ø ≥ 4.0). Reaction path analysis indicated that reaction pathway branched from C2 H3 reacting with methyl radical, which competes with C2 H2 production, showed relatively low contribution to benzene formation at moderate equivalence ratio. Therefore, improvements of chemical kinetics with further consideration of reactions with methyl radical are necessary for precise prediction of products where abundant amounts of methyl radical exist.