New insights into methane-oxygen ion chemistry

Awad Alquaity, Bingjie Chen, Jie Han, Hatem Selim, Memdouh Belhi, Yasin Karakaya, Tina Kasper, Mani Sarathy, Fabrizio Bisetti, Aamir Farooq

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


External electric fields may reduce emissions and improve combustion efficiency by active control of combustion processes. In-depth, quantitative understanding of ion chemistry in flames enables predictive models to describe the effect of external electric fields on combustion plasma. This study presents detailed cation profile measurements in low-pressure, burner-stabilized, methane/oxygen/argon flames. A quadrupole molecular beam mass spectrometer (MBMS) coupled to a low-pressure (P =30Torr) combustion chamber was utilized to measure ion signals as a function of height above the burner. Lean, stoichiometric and rich flames were examined to evaluate the dependence of ion chemistry on flame stoichiometry. Additionally, for the first time, cataloging of flame cations is performed using a high mass resolution time-of-flight mass spectrometer (TOF-MS) to distinguish ions with the same nominal mass. In the lean and stoichiometric flames, the dominant ions were HO, CHO , CHO, CHO and CHO, whereas large signals were measured for HO, CH and CHO in the rich flame. The spatial distribution of cations was compared with results from numerical simulations constrained by thermocouple-measured flame temperatures. Across all flames, the predicted HO decay rate was noticeably faster than observed experimentally. Sensitivity analysis showed that the mole fraction of HO is most sensitive to the rate of chemi-ionization CH+O↔CHO +E. To our knowledge, this work represents the first detailed measurements of positive ions in canonical low-pressure methane flames.
Original languageEnglish (US)
Pages (from-to)1213-1221
Number of pages9
JournalProceedings of the Combustion Institute
Issue number1
StatePublished - Jun 15 2016

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was supported by an Academic Excellence Alliance (AEA) grant, titled Electromagnetically-Enhanced Combustion, awarded by the Office of Sponsored Research at King Abdullah University of Science and Technology (KAUST).


Dive into the research topics of 'New insights into methane-oxygen ion chemistry'. Together they form a unique fingerprint.

Cite this