基于可调谐激光吸收光谱技术(TLAS)的内燃机排放组分浓度测试技术研究

Research on the Measurement of IC Engine Exhaust Gas Component by Tunable Laser Absorption Spectroscopy Technique

开展基于可调谐激光吸收光谱(tunable laser absorption spectroscopy,TLAS)的内燃机排放中气体组分浓度检测技术研究。选取NO气体作为试验室静态测试的目标气体,利用可调谐带间级联激光器(interband cascade lasers,ICL)作为探测光源,采用直接探测法及谐波探测法对4种不同浓度的标准NO气体进行测试,结果与标准气真实浓度吻合度较高。直接探测法中,探测相对误差均方根为2.6%,体积浓度的最大绝对误差为18.6×10^(-6),理论探测极限可达2×10^(-6);谐波探测相对误差均方根为1.4%,最大绝对误差为13×10^(-6),理论探测极限可达10^(-7)。数据处理过程中引入温度修正算法,可实现温度波动下的准确测量。同时,对不同流速下的标准气体进行了在线测量,结果表明气体的流动性对测试结果并无影响。本研究表明:TLAS方法动态响应特性好,环境适应性强,可根据瞬态环境参数进行实时修正,可以在复杂的测试环境下实现高精度、高灵敏度瞬态测量。

ATLAS technigue was used to measure the concentrations of the exhaust gas components. To this end, selecting NO gas as a target gas for laboratory static test and using an IC laser as a detector light source, a direct detection method and harmonic detection method were used to measure four different concentrations of a standard NO gas, and the test results were consistent with the real concentrations of the standard gas. When using the direct detection method, the root-mean-square of the relative error was 5.4 % , with a maximum absolute error of 18.6 ×10^-6, and the theoretical resolution of 2 × 10^-6, while for the harmonic detection method, the root-mean-square of the relative error was 1.4% with a maximum absolute error of 13 × 10^-6 , and theoretical resolution of 10^-7. In data processing, the temperature correction was used to achieve accurate measurements at temperature fluctuation. At the same time, the standard gas concentrations with different velocity were measured on line, which indicated that the gas flowability had no effect on the test results. Study shows that the TLAS method has good dynamic response, and environmental adaptability, so that it can be used in real-time correction for transient environmental conditions in order to achieve high precision and sensitivity of transient measurements in a complex test environment.