TY - JOUR

T1 - Structure of Premixed n-Heptane/Oxygen/Argon Flames at 2–6 atm: A Mass Spectrometric and Numerical Study

AU - Knyazkov, D. A.

AU - Shmakov, A. G.

AU - Osipova, K. N.

AU - Dmitriev, A. M.

AU - Bolshova, T. A.

N1 - This work was supported by the Ministry of Science and Higher Education of the Russian Federation, agreement dated 24.04.2024, no. 075-15-2024-543.

PY - 2025/6/3

Y1 - 2025/6/3

N2 - Abstract: n-Heptane is an important component of liquid motor fuels, which is included in the composition of reference fuel mixtures for determining the octane number of gasoline, and it is also the most important component of surrogate fuels. Despite a large number of experimental and numerical studies on the kinetics of its oxidation and combustion, there are very few data on the composition of intermediate products of its combustion at elevated pressures. In this work, we used flame-sampling molecular-beam mass spectrometry (MBMS) to study the chemical structure of flames of premixed stoichiometric (ϕ = 1.0) and rich (ϕ = 1.5) n-heptane/O2/Ar mixtures stabilized on a flat-flame burner at pressures of 2, 4 and 6 atm. The mole fraction profiles of key intermediate products of n-heptane combustion, including atoms and radicals, and acetylene and propargyl as precursors of polycyclic aromatic hydrocarbons (PAHs) were measured. Numerical simulation of the flame structure were performed using various detailed chemical-kinetic mechanisms of heavy hydrocarbon combustion proposed in the literature. It was found that the models adequately described the experimentally observed changes in the composition of combustion products both with increasing pressure and with increasing fuel equivalence ratio. Although experiments in rich flames showed a complete absence of acetylene in the final combustion products, all models predicted a high acetylene content, which indicated the need for further study of the kinetics of C2H2 conversion in combustion of rich mixtures.

AB - Abstract: n-Heptane is an important component of liquid motor fuels, which is included in the composition of reference fuel mixtures for determining the octane number of gasoline, and it is also the most important component of surrogate fuels. Despite a large number of experimental and numerical studies on the kinetics of its oxidation and combustion, there are very few data on the composition of intermediate products of its combustion at elevated pressures. In this work, we used flame-sampling molecular-beam mass spectrometry (MBMS) to study the chemical structure of flames of premixed stoichiometric (ϕ = 1.0) and rich (ϕ = 1.5) n-heptane/O2/Ar mixtures stabilized on a flat-flame burner at pressures of 2, 4 and 6 atm. The mole fraction profiles of key intermediate products of n-heptane combustion, including atoms and radicals, and acetylene and propargyl as precursors of polycyclic aromatic hydrocarbons (PAHs) were measured. Numerical simulation of the flame structure were performed using various detailed chemical-kinetic mechanisms of heavy hydrocarbon combustion proposed in the literature. It was found that the models adequately described the experimentally observed changes in the composition of combustion products both with increasing pressure and with increasing fuel equivalence ratio. Although experiments in rich flames showed a complete absence of acetylene in the final combustion products, all models predicted a high acetylene content, which indicated the need for further study of the kinetics of C2H2 conversion in combustion of rich mixtures.

KW - acetylene

KW - combustion

KW - flame structure

KW - molecular beam mass spectrometry

KW - n-heptane

KW - numerical simulation

KW - soot precursors

UR - https://www.mendeley.com/catalogue/25da1506-9595-3396-ad2b-8d0c7c0dfbdb/

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-105007148865&origin=inward&txGid=9055afa691bdf2a60e0343b989d7ca5b

U2 - 10.1134/S0023158424602444

DO - 10.1134/S0023158424602444

M3 - Article

VL - 66

SP - 1

EP - 14

JO - Kinetics and Catalysis

JF - Kinetics and Catalysis

SN - 0023-1584

IS - 1

ER -