TDLAS中基于谐波信号的气体绝对吸收强度在线测量算法研究

项目名称： TDLAS中基于谐波信号的气体绝对吸收强度在线测量算法研究

项目编号： No.11502004

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 数理科学和化学

项目作者： 贾军伟

作者单位： 北京东方计量测试研究所

项目金额： 25万元

中文摘要： 可调谐二极管激光吸收光谱（TDLAS）中直接吸收法通过测量绝对吸收强度来计算待测气体温度和浓度，其物理概念清晰，但容易受到颗粒物浓度等影响，而具有高信噪比和灵敏度的波长调制法则需要通过标定实验或复杂的算法来确定气体参数。为此，本项研究拟通过吸收光谱理论和波长调制理论，推导出蕴含分子吸收信息的谐波通项表达式，并在此基础上分析谐波信号与待测气体绝对吸收强度之间的关系，建立一种基于谐波信号的绝对吸收强度在线测量算法，并通过数值模拟技术对其可靠性进行证明；随后利用该算法在实验室条件下测量多种工况环境下CO2分子特征吸收谱线的绝对吸收强度，将其与理论计算值和直接吸收法测量结果进行比较，验证算法的精度并对其进行优化。项目预期可以结合TDLAS中直接吸收和波长调制的优点，建立一种高精度的、适用范围广的、基于谐波信号的绝对吸收强度在线测量算法，使得波长调制法无需通过标定实验即可实现气体温度和浓度的测量。

中文关键词： 动态实验；测压；可调谐二极管激光吸收光谱；气体温度；气体浓度

英文摘要： In tunable diode laser absorption spectroscopy (TDLAS), the traditional direct absorption spectroscopy (DAS) can directly determine gas temperature and concentration by using the measured absolute absorbance. The theory is simple while DAS is easily affected by particle concentration and laser intensity fluctuation. Wavelength modulation spectroscopy (WMS) has high signal-to-noise ratio (SNR) and sensitivity but it needs the complex calibration experiment and algorithm to infer the gas parameters. Therefore, in this research, the expressions of the harmonic signals, which contain the absorption information, are derived basing on the absorption and wavelength modulation spectroscopy. Then a measurement method for gas absolute absorbance is developed basing on the harmonic signals. The reliability of this method is validated by the mathematic simulation. To verify and to optimize this method, the transition of CO2 is selected to measure the absolute absorbance with various conditions in laboratory. And the experimental results are also compared with the theoretical calculation values and DAS. This research is expected to establish a high precision, wide application method to determine the absolute absorbance based on the harmonic signals, which combines the advantages of DAS and WMS in TDLAS, and makes WMS get rid of the calibration experiment in gas temperature and concentration detections.

英文关键词： Dynamic measurement ;Pressure measurement;Tunable diode laser absorption spectroscopy;Gas temperature;Gas concentration