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针对传统光学传感技术气体选择性不高与激光光源在气体检测中需严格控温的缺点,采用红外宽带光源进行CH4气体的检测,并结合实验所用气室与光电探测器件参数,利用HITRAN数据库对CH4吸收进行仿真计算,得出了系统理论探测下限与光强信号之间的变化规律。在不同CH4浓度梯度的实际测量中,采用快速傅里叶变换(FFT)与Savitzky-Golay数字滤波相结合的方法对系统噪声进行处理,将外部因素引起的噪声干扰降低了1个数量级,在不同CH4浓度梯度的实际测量中,利用CH4浓度和光强调制系数的对应关系对系统进行了标定,并通过数据拟合得到CH4浓度的反演曲线,相关系数达到0.998 83,测量灵敏度低至20×10-6,系统检测下限约为50×10-6;与传统化学传感器相比,系统测量误差小于1.5~7.0%,实现了CH4浓度的精确检测。
Aiming at the shortcomings of traditional optical sensing technology such as low gas selectivity and strict control of temperature in gas detection, an infrared broadband light source was used to detect CH4 gas. Combining with the gas chamber and photodetection device parameters used in the experiment, the HITRAN database The simulation of CH4 absorption is carried out, and the law of variation between the lower limit of system theory detection and light intensity signal is obtained. In the actual measurement of different CH4 concentration gradients, the system noise was processed by a combination of Fast Fourier Transform (FFT) and Savitzky-Golay digital filtering, which reduced the noise interference caused by external factors by an order of magnitude. In different In the actual measurement of CH4 concentration gradient, the system was calibrated by the correspondence between CH4 concentration and light intensity modulation coefficient, and the inversion curve of CH4 concentration was obtained by data fitting, the correlation coefficient reached 0.998 83 and the measurement sensitivity was as low as 20 × 10 -6, and the lower limit of system detection is about 50 × 10-6. Compared with the traditional chemical sensors, the measurement error of the system is less than 1.5-7.0%, which achieves the accurate detection of CH4 concentration.