In situ measurements of CO concentration were recorded with tunable diode-laser absorption spectroscopy techniques in both the exhaust and the immediate post-flame regions of an atmospheric-pressure flat-flame burner operating on ethylene air. Two room-temperature cw single-mode InGaAsSb/AlGaAsSb diode lasers operating near 2.3 µm were tuned over individual transitions in the CO first overtone band (v′ = 2 ← v″ = 0) to record high-resolution absorption line shapes in the exhaust duct [79 cm above the burner, ∼470 K; R(15) transition at 4311.96 cm-1] and the immediate postflame zone [1.5 cm above the burner, 1820–1975 K; R(30) transition at 4343.81 cm-1]. The CO concentration was determined from the measured absorption and the gas temperature, which was monitored with type-S thermocouples. For measurements in the exhaust duct, the noise-equivalent absorbance was ∼3 × 10-5 (50-kHz detection bandwidth, 50-sweep average, 0.1-s total measurement time), which corresponds to a CO detection limit of 1.5 ppm m at 470 K. Wavelength modulation spectroscopy techniques were used to improve the detection limit in the exhaust to ∼0.1 ppm m (∼500-Hz detection bandwidth, 20-sweep average, 0.4-s total measurement time). For measurements in the immediate postflame zone, the measured CO concentrations in the fuel-rich flames were in good agreement with chemical equilibrium predictions. These experiments demonstrate the utility of diode-laser absorption sensors operating near 2.3 µm for in situ combustion emission monitoring and combustion diagnostics.
© 2000 Optical Society of AmericaFull Article | PDF Article
More Like This
Michael E. Webber, Suhong Kim, Scott T. Sanders, Douglas S. Baer, Ronald K. Hanson, and Yuji Ikeda
Appl. Opt. 40(6) 821-828 (2001)
Appl. Opt. 40(27) 4894-4903 (2001)
Wen Yu Peng, Christopher S. Goldenstein, R. Mitchell Spearrin, Jay B. Jeffries, and Ronald K. Hanson
Appl. Opt. 55(33) 9347-9359 (2016)