Abstract
A diode-laser sensor system has been applied to measure the concentrations of NO, N2O, CO, CO2, and O2 i n combustion gases using absorption spectroscopy and fast extraction-sampling techniques. Measured survey spectra of the NO 3 v band (R branch) and H2O lines from the v2 + v3 band in the spectral region from 5556 cm to 5572 cm were recorded and compared to calculated spectra to select optimum transitions for NO detection. Similarly, measured survey spectra of the N2O 3v3 band from 6535 cm to 6600 cm were used to identify optimum transitions for N2O detection. High-resolution NO absorption measurements (R2(7.5) and R,(7.5) lines) were recorded in a fast-flow multipass cell containing probe-sampled combustion gases to determine NO concentrations in a laminar, premixed CH4/air flame, seeded with NH3. For fuel-lean conditions, the measured NO mole fractions corresponded to 68% of the injected NH3. For fuel-rich conditions, the fraction of NH3 converted to NO decreased with increasing equivalence ratio. In additional experiments, CO, CO2, and O2 absorption measurements (R(13) line of the 3v band, R(16) line of the 2v,+2v2 + v3 band, and RQ(7,8) line of the &'£j(v' = 0)<— X^Jg(v=0) band, respectively) were used to determine species concentrations above a laminar, premixed CH4/air flame. Good agreement was found between measured CO, CO2, and O2 concentrations and calculated chemical equilibrium values.
Published Version
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