Research on temperature-pressure compensation algorithm for concentration calibration in TDLAS gas detection system

With the rapid development of industry, the content of greenhouse gases such as CH4 in the atmosphere is increasing, which has a certain impact on human production and life. Therefore, high-precision gas detection has been a research hotspot in the field of gas sensing, but the temperature and pressure changes in the environment will affect the line shape of the gas absorption spectra, resulting in errors in gas concentration monitoring. This paper presents a temperature-pressure compensation algorithm. Firstly, the temperature and pressure compensation coefficients under different ambient temperatures and pressures are obtained by simulation. Then, the temperature and pressure of the ambient gas are monitored, and the detection signal is compensated in real time. Finally, the monitored gas concentration is calculated according to the linear relationship between the detection signal amplitude and the gas concentration. The experimental results show that the detection accuracy of the gas detection system is significantly improved after using the compensation algorithm to compensate for the signal amplitude. Taking the measurement of 2 ppm CH₄ concentration as an example, the maximum error of CH₄ concentration obtained after using the temperature-pressure compensation algorithm is 5%, while the maximum error of CH₄ concentration obtained without using the temperature-pressure compensation algorithm is 9.5%. The system was also utilized for long-term stability monitoring of 2 ppm CH₄, and the concentration fluctuation of the system was only 0.04 ppm. According to theoretical and experimental proofs, the monitoring stability of the TDLAS gas sensing system can be effectively improved and the monitoring error can be reduced by this temperature-pressure compensation algorithm.