Gas concentration estimation using least-squares curve fitting

Abstract

This paper presents a modeling approach that integrates least-squares curve fitting to improve the ac-curacy of gas concentration estimation using tunable diode laser absorption spectroscopy (TDLAS). A mathematical model accounts for absorption, scattering, and reflectance effects. The Levenberg–Marquardt algorithm is applied to extract the fundamental and even harmonic components, enabling precise determination of gas concentration. Experimental results demonstrate a strong correlation between the absorption pulse amplitude and methane concentration with the coefficient of determination R2 value of 0.989. The proposed method proves efficient, requiring only a few signal cycles for gas concentration estimation, making it suitable for real-time monitoring systems.