Research on the measurement of CH₄ concentration based on dual-band weighted combination model

Abstract

A detection system based on supercontinuum laser absorption spectroscopy (SCLAS) technology was built up in this study. The absorption spectra of CH₄ in different near-infrared bands were measured based on the SCLAS detection system. Under normal temperature and pressure, the absorption spectra of CH₄ at different concentrations in the bands of 1 319–1 339 nm and 1 656–1 676 nm were measured. The linear models of CH₄ concentrations in different bands were established. The fitting coefficient (R²) of the models were 0.995 7 and 0.996 1, respectively. In order to improve the concentration inversion ability of the model, the weight distribution of each model was determined by R² and sum of squared error (SSE) to obtain a new combined model. The maximum relative error of the concentration inversion was reduced from 2.3% to 1.3%. The experimental results show the feasibility of applying the SCLAS technology to CH₄ concentration measurement, and it also verifies that the dual-band combination model can improve the accuracy and stability of the CH₄ concentration measurement.

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