Environmental monitoring of methane utilizing multispectral NDIR gas sensing for compensation of spectral impact from water vapor in air

• A multispectral nondispersive infrared (NDIR) sensor was developed for simultaneous detection of methane and water vapor in air. The NDIR sensor is capable of measuring optic transmission in the CH4 absorption spectra at 3.375 μm and the H2O absorption spectra at 2.7 μm. Data from a third channel, 3.95 μm, is used as reference value for 'zero-level' calibration. The actual CH4 concentration is retrieved by adjusting the data obtained in the CH4 spectra with respect to the concentration sensed in the H2O spectra. A calibration procedure was developed and tested, which involves matching of the absorbed light energy in the CH4 and the H2O spectrum in humid reference environments. A compensation algorithm for elimination of humidity impact was developed and validated in environments with variable CH4 and H2O concentrations. By implementing the multispectral approach, and the developed algorithm, an uncertainty of 15-25 ppm relative the reference concentrations was achieved. For a concentration range valid for environmental monitoring applications this should be compared to an uncertainty of 180-200 ppm for the non-corrected CH4 concentration. 

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik -- Annan elektroteknik och elektronik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering -- Other Electrical Engineering, Electronic Engineering, Information Engineering (hsv//eng)

Nyckelord

environmental

Methane

monitoring

NDIR

Publikations- och innehållstyp

ref (ämneskategori)

kon (ämneskategori)