高精密恒温系统在NDIR气体分析仪中的应用

当前基于非分光红外（NDIR）技术的气体分析仪设计过程中存在很多干扰源,这些干扰源对检测精度影响的轻重程度各有不同,其中,红外池中,温度的稳定性对气体的吸收影响大,此外,对于特定的吸收气体,恒温点同样重要。设计了一种基于增量式PID算法的高精度温控系统,选择对气体吸收影响最小的恒温点,并控温范围为±0.1℃,相比现有同类温控系统,精度提高近10倍。通过试验比较不控温情况下的结果和应用在本恒温系统中的测试结果表明：高精度恒温系统下,NDIR气体分析仪的信噪比得到了明显改善。该成果将直接应用到国家＂十二·五＂计划项目中。

Application of high precision constant temperature system in NDIR gas analyzer

At present there are many interference source based on design process of gas analyzer of NDIR technology, impact of these disturbance on detection precision as well as severity is different, among which,in IR pool, effects of temperature stability on absorption of gas is large, in addition to specific absorbing gas, constant temperature point is also important. Design a high precision temperature control system based on incremental PID algorithm, select constant temperature point which has the minimum effect on gas absorption and range of temperature control is ±0.1℃, compared with the existing temperature control system of the same kind, precision is improved about 10 times. The test results are compared with the experimental results under the conditions without temperature control and applied in constant temperature system, it shows that with high precision constant temperature system, SNR of NDIR gas analyzer is improved obviously. The fruit will be directly applied to the national ＂12 · 5 ＂ project.