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差分吸收光谱法(DOAS)原理简单、检测精度高、响应速度快、可应用于非接触和连续在线监测。本文利用差分吸收光谱法对NH_3浓度进行在线反演。不同于传统的DOAS中选取部分波长点光谱数据反演气体浓度,本文充分利用反演波段内所有实验数据,联立超定方程组,并用最小二乘法求解。为了消除温度对反演结果的影响,利用20℃与其他温度下NH_3分子数密度比的比值和对应温度的关系拟合出温度补偿函数对反演结果进行温度补偿。实验结果表明该方法反演NH_3浓度时具有较高的反演精度。
Differential absorption spectroscopy (DOAS) has the advantages of simple principle, high detection precision and fast response, which can be applied to non-contact and continuous on-line monitoring. In this paper, differential absorption spectroscopy NH3 concentration on-line inversion. Different from the traditional DOAS, we choose some wavelength points to retrieve the gas concentrations. This paper makes full use of all the experimental data in the inversion band to set up the simultaneous over-determined equations and solve them by the least square method. In order to eliminate the influence of temperature on the inversion results, the temperature compensation function was fitted by using the ratio of the number density ratio of NH 3 molecules at 20 ℃ and other temperatures to the corresponding temperature, and the temperature was compensated. The experimental results show that this method has higher inversion accuracy when inverting NH_3 concentration.