High-temperature dual-species (CO/NH3) detection using calibration-free scanned-wavelength-modulation spectroscopy at 2.3 μm

作者：Raza, Mohsin; Ma, Liuhao^*; Yao, Shunchun; Chen, Longfei; Ren, Wei^*

来源：Fuel, 2021, 305: 121591.

DOI：10.1016/j.fuel.2021.121591

• Absorption spectroscopy
• Scanned-wavelength-modulation spectroscopy
• In-situ sensing
• Ammonia
• Carbon monoxide
• Distributed feedback laser

A dual-species sensor based on scanned-wavelength-modulation spectroscopy (scanned-WMS) with the 2f/1f detection is developed for calibration-free CO and NH3 detection in high-temperature environments. A 2.3 mu m distributed feedback (DFB) diode laser was used to exploit the CO and NH3 lines centred at 4300.7 cm-1 and 4301.13 cm-1, respectively. The DFB laser was scanned across the target absorption lines at 100 Hz with fast sinusoidal modulation at 5 kHz. The spectral fitting strategy was employed to least-square fit the simulated and measured WMS-2f/1f spectra. The integrated absorbance of target transitions inferred from the scanned-WMS2f/1f spectral fitting was used to determine the species concentration. The performance of the developed sensor was validated by simultaneously measuring species concentrations under various temperatures (300-700 K) and at 1 atm in a high-temperature gas cell. The noise equivalent absorption (NEA) coefficient of 3.5 x 10-6 cm- 1 for CO and 4.9 x 10-7 cm-1 for NH3 was achieved at 700 K with an absorption path length of 20 cm. The developed dual-species sensor has the potential to be applied in the exhaust of practical combustion systems such as NH3 monitoring for NOx abatement in selective catalytic reduction (SCR) aftertreatment and CO sensing for optimizing combustor efficiency.

• 单位
  Beijing University of Aeronautics and Astronautics(BUAA); Wuhan University of Technology