KAUST DepartmentChemical Engineering Program
Chemical Kinetics & Laser Sensors Laboratory
Clean Combustion Research Center
Combustion and Pyrolysis Chemistry (CPC) Group
Mechanical Engineering Program
Physical Science and Engineering (PSE) Division
Reactive Flow Modeling Laboratory (RFML)
Online Publication Date2016-06-15
Print Publication Date2017
Permanent link to this recordhttp://hdl.handle.net/10754/627028
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AbstractExternal 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.
CitationAlquaity ABS, Chen B, Han J, Selim H, Belhi M, et al. (2017) New insights into methane-oxygen ion chemistry. Proceedings of the Combustion Institute 36: 1213–1221. Available: http://dx.doi.org/10.1016/j.proci.2016.05.053.
SponsorsThis 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).