CH₄, C₂H₆, and C₂H₄ Multi-Gas Sensing Based on Mid-Infrared Spectroscopy and SVM Algorithm.

Area of Science:

• Spectroscopy
• Gas sensing technology
• Environmental monitoring

Background:

• Accurate detection of multiple gases like methane (CH4), ethane (C2H6), and ethylene (C2H4) is crucial for environmental and industrial applications.
• Existing multi-gas sensing methods can be complex, bulky, and expensive.
• Mid-infrared (MIR) spectral absorption offers a selective and sensitive approach for gas detection.

Purpose of the Study:

• To develop a compact and cost-effective multi-gas sensing system for simultaneous detection of CH4, C2H6, and C2H4.
• To achieve low limits of detection (LOD) for these target gases.
• To implement a robust algorithm for accurate concentration calculation in mixed gas samples.

Main Methods:

• Utilized a broadband infrared source, a hollow waveguide (HWG) absorption cell, and a tunable Fabry-Pérot (FP) detector.
• Employed a support vector machine (SVM) algorithm for multi-gas concentration calculation.
• Optimized sample selection for stimulated absorption spectra to enhance measurement accuracy.

Main Results:

• Achieved LODs of 7.33 ppm for CH4, 2.13 ppm for C2H6, and 8.09 ppm for C2H4.
• Reported root mean square error of prediction (RMSEP) values of 15.91 ppm (1.26%) for CH4, 1.64 ppm (0.57%) for C2H6, and 6.95 ppm (0.55%) for C2H4.
• Successfully generated stimulated absorption spectra for mixed gases, enabling accurate individual component quantification.

Conclusions:

• The developed MIR spectral absorption system provides a simple, miniaturized, and cost-effective solution for simultaneous multi-gas sensing.
• The SVM algorithm effectively calculates concentrations of CH4, C2H6, and C2H4 in mixtures.
• This technology holds promise for various applications requiring precise multi-gas monitoring.