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.