非线性吸收对多组分气体分析的影响及其修正方法

Influence of Nonlinear Absorption on Simultaneous Multi-Gas Analysis and Its Modification Method

利用非分散红外(NDIR)技术研究了非线性吸收现象对多组分气体分析交叉干扰扣除的影响及其修正方法。理论上推导了由于非线性吸收导致的干扰系数变化对系统测量准确度的影响。对常规的干扰方程组进行了修正,使用干扰函数来定量分析气体间的交叉干扰,当测量气体存在非线性吸收时,干扰函数也会发生相应变化。基于最小二乘法,以三阶多项式为拟合模型,拟合出了系统的干扰函数。利用拟合的干扰函数,通过实验证明了提出的修正方法在系统存在非线性吸收现象时仍能有效地扣除气体间的交叉干扰。

The influence of nonlinear absorption on cross interference correction in multi-gas analysis and modification method when gases are measured simultaneously are studied by non-dispersive infrared （NDIR） technique. The influence of interference coefficient variation caused by nonlinear absorption on system measurement accuracy has been deduced theoretically. The new interference equation modified from the conventional one uses the interference function to quantify the cross interference among the target gases. The interference functions vary proportionally with the nonlinear absorption. They can be obtained by least-squares fitting using the 3-order polynomials. Experiments show that the cross interference is corrected effectively by utilizing the fitted interference function even if the nonlinear absorption still exists in the system.