TY - JOUR

T1 - Experimental and kinetic modeling study of the positive ions in premixed ethylene flames over a range of equivalence ratios

AU - Knyazkov, Denis A.

AU - Cherepanov, V.

AU - Kiselev, Vitaly G.

AU - Gerasimov, Ilya E.

AU - Kasper, Tina

AU - Shmakov, Andrey G.

N1 - Funding Information: This work is supported by the Ministry of Science and Higher Education of the Russian Federation (Project No: 075–15–2020–806 ) Publisher Copyright: © 2022 Elsevier Inc. All rights reserved.

PY - 2023

Y1 - 2023

N2 - Understanding the ion chemistry in flames is crucial for developing ion sensitive technologies for controlling combustion processes. In this work, we measured the spatial distributions of positive ions in atmospheric-pressure burner-stabilized premixed flames of ethylene/oxygen/argon mixtures in a wide range of equivalence ratios π = 0.4+1.5. A flame sampling molecular beam system coupled with a quadrupole mass spectrometer was used to obtain the spatial distributions of cations in the flames, and a high mass resolution time-of-flight mass spectrometer was utilized for the identification of the cations having similar m/z ratios. The measured profiles of the flame ions were corrected for the contribution of hydrates formed during sampling in the flames slightly upstream the flame reaction zone. We also proposed an updated ion chemistry model and verified it against the experimental profiles of the most abundant cations in the flames. Our model is based on the kinetic mechanism available in the literature extended with the reactions for C3H5+ cation. Highly accurate W2-F12 quantum chemical calculations were used to obtain a reliable formation enthalpy of C3H5+. The model was found to reproduce properly the measured relative abundance of the key oxygenated cations (viz., CH5O+, C2H3O+) in the whole range of equivalence ratios employed, and the C3H5+ cation abundance in the richest flame with π=1.5, but significantly underpredicts the relative mole fraction of C3H3+, which becomes a key species under fuel-rich conditions. Apart from this, several aromatic and cyclic CxHy cations dominating under fuel-rich conditions were identified. We also considered the most important directions for the further refinement of the mechanism.

AB - Understanding the ion chemistry in flames is crucial for developing ion sensitive technologies for controlling combustion processes. In this work, we measured the spatial distributions of positive ions in atmospheric-pressure burner-stabilized premixed flames of ethylene/oxygen/argon mixtures in a wide range of equivalence ratios π = 0.4+1.5. A flame sampling molecular beam system coupled with a quadrupole mass spectrometer was used to obtain the spatial distributions of cations in the flames, and a high mass resolution time-of-flight mass spectrometer was utilized for the identification of the cations having similar m/z ratios. The measured profiles of the flame ions were corrected for the contribution of hydrates formed during sampling in the flames slightly upstream the flame reaction zone. We also proposed an updated ion chemistry model and verified it against the experimental profiles of the most abundant cations in the flames. Our model is based on the kinetic mechanism available in the literature extended with the reactions for C3H5+ cation. Highly accurate W2-F12 quantum chemical calculations were used to obtain a reliable formation enthalpy of C3H5+. The model was found to reproduce properly the measured relative abundance of the key oxygenated cations (viz., CH5O+, C2H3O+) in the whole range of equivalence ratios employed, and the C3H5+ cation abundance in the richest flame with π=1.5, but significantly underpredicts the relative mole fraction of C3H3+, which becomes a key species under fuel-rich conditions. Apart from this, several aromatic and cyclic CxHy cations dominating under fuel-rich conditions were identified. We also considered the most important directions for the further refinement of the mechanism.

KW - Cations

KW - Flame

KW - Flame sampling molecular beam mass spectrometry

KW - Ion chemistry

KW - Ion thermochemistry data

UR - http://www.scopus.com/inward/record.url?scp=85139181160&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/d3068996-9acf-3092-a459-782538ad5d56/

U2 - 10.1016/j.proci.2022.07.157

DO - 10.1016/j.proci.2022.07.157

M3 - Article

AN - SCOPUS:85139181160

VL - 39

SP - 1753

EP - 1761

JO - Proceedings of the Combustion Institute

JF - Proceedings of the Combustion Institute

SN - 1540-7489

IS - 2

ER -