可调谐半导体激光吸收光谱技术对CO2浓度的测量研究

Measurement of CO2 Concentration by Tunable Diode Laser Absorption Spectroscopy

CO2作为地球大气中第三大含量的痕量气体,也是含量最大的温室气体,会导致气候变暖和生态系统的破坏等一系列环境问题,因此CO2浓度的准确测量具有重要意义。可调谐半导体激光吸收光谱(TDLAS)技术利用气体的特征吸收光谱,可以对气体进行无需预处理的高灵敏度测量。基于TDLAS技术,搭建了采用直接吸收光谱的实验系统,根据与水分子的对比分析,选择CO2在2004 nm附近的强吸收线,在27 m的光程下达到的检测限为2.97×10-6。采用LGR气体分析仪作为对比,测量了室内空气的CO2浓度,无人和有人时二者的相关系数分别为0.9965和0.9875,在CO2浓度变化趋势上表现出了良好的一致性。

As the third largest amount of trace gases in the Earth's atmosphere and maximum content of greenhouse gases,CO2 will lead to climate warming and damage to ecosystems and a series of environmental problems.Therefore,accurate measurement of CO2 concentration is of great significance.Tunable Diode Laser Absorption Spectroscopy(TDLAS)technology utilizes the characteristic absorption spectrum of gases to measure the gas concentration with high sensitivity,which does not require pretreatment.Based on TDLAS technology,an experimental system with direct absorption spectroscopy was built.According to a comparative analysis with water molecules,the system selects the strong absorption line of CO2 near 2004 nm,and the detection limit was 2.97×10-6 at 27 m optical path length.Using the LGR gas analyzer as a contrast,the CO2 concentration of the indoor air was measured,and the correlation coefficients of the two instruments were 0.9965 and 0.9875,which showed that good consistency in the variation trend of CO2 concentration.