Applying external electric field show great performance on emission control, spark ignition, and combustion efficiency improvement in internal combustion engines and gas turbines. To understand the reason why soot, NOx and other pollutants can be suppressed by electric field, ion chemistry needs to be studied and developed. In this work, positive ions were measured in low pressure (P=60 Torr), burner stabilized, rich premixed methane/oxygen/argon flames. Detailed ion profiles were measured and identified as signals versus height-above-burner by utilizing a quadrupole molecular beam mass spectrometry (MBMS). Three equivalence ratios (ϕ=1.5, 1.8 and 2.0) were applied to investigate ion chemistry. Top three measured ions were identified as H3O+, C3H3+ and C2H3O+, along with some minor ions. When flames were slightly rich (ϕ=1.5), H3O+ had largest signal in the flame zone; however, when flames were very rich (ϕ=1.8 and 2.0), dominant ions changed to C3H3+, suggesting a different ion chemistry. Neutrals and radicals in the same flame (ϕ=1.5) were additionally measured by Photo Ionization Time-Of-Flight Molecular Beam Mass Spectrometry (PI-TOF-MBMS) to further investigate neutral-ion reactions. Correlations between neutrals and ions indicated major ion structures and ion reaction channels. This work can complete experimental data for methane flames combined with previous research, and offer new insights for future ion chemistry development.
|Original language||English (US)|
|Title of host publication||11th Asia-Pacific Conference on Combustion, ASPACC 2017|
|State||Published - Jan 1 2017|