Gas concentration detection method based on infrared absorption spectroscopy technology

According to the Lambert-Beer law, we derived mathematical model to measure the target gas concentration, and deduced the function which could be used for characterizing the relationship of the output voltage of the two detectors and the target gas concentration. The aim of calibration process is to determine the values of those two constants which depend on the length of the chamber, the gas absorption coefficient and the detector voltage detectivity in the above expression. Secondly, according to the feature of the measurements' zero point changes with current temperature, the relationship between zero point and temperature was formulated. It can be used for zero temperature compensation and correlation of coefficient calculation. The scale temperature compensation method is the way to revise the function expression of the output voltage of the two detectors and the target gas concentration by introducing scale temperature compensation factor. The corrected function expression is used for compensating scale temperature and calculating the compensation coefficient of scale temperature compensation. Finally, the calibration and temperature compensation method above was applied to coal mine non-dispersive infrared methane transducer and the test results of standard gas samples testing under various ambient temperatures conform to the requirements in infrared methane sensor standard.