1, 1, 1, 3, 4, 4, 4-7氟-3-(3氟甲基)-2-丁酮（C5-PFK）气体因其优良的电气绝缘性能和良好的环保特性受到国内外广泛关注。 制备高精度的C5-PFK混气并实现对其混合比的精准检测, 有利于对C5-PFK混气的科学论证, 最大限度的减少电力隐患。 采用FTIR实验, 结合B3LYP方法进行光谱理论计算, 对C5-PFK气体的红外光谱吸收特性进行了研究; 针对测试环境中可能存在的CO2及微水气体, 在相同的温压及光程条件下进行了谱线交叉干扰分析; 基于非分散性红外线(NDIR)技术对C5-PFK混气混合比传感器进行了仿真测试, 开展了传感器硬件系统的整体设计。 根据传感器的输出特性, 建立了BP神经网络温度补偿模型, 并对传感器的重复性及示值误差进行了测试。 结果表明: C5-PFK气体的强吸收峰位置分别为1 200、 1 262及1 796 cm-1, 分子理论计算与气体实测的红外光谱吻合较好; 合成空气背景下1 262 cm-1位置CO2气体的吸光度为6.04×10-7, 150 nm滤波带宽内微水峰面积影响因子约为3.15×10-3, 谱线交叉干扰可忽略不计, 采用NDIR技术选择1 262 cm-1位置实现混合比检测切实可行; 以量程追踪光程, 传感器仿真测试结果显示6.5 mm光程可实现0~15%的C5-PFK混气混合比的检测。 传感器输出特性显示: 吸收变量SA/SB值随温度的升高而减小, 呈现非线性关系; 10%的C5-PFK/Air混气在BP神经网络算法温度补偿前后最大示值误差分别为29.23%及1.29%, 补偿后输出吸收变量SA/SB值基本保持不变; 传感器重复性测试显示RSD为0.27%, 小于3%; 不同浓度对应的传感器示值的线性拟合系数R2为0.999, 最大示值误差为2.47%。 综上, 验证了该检测方法及其传感器在C5-PFK气体混合比检测范围、 抗干扰能力及可靠性等方面优势, 为C5-PFK混气电气设备混合比检测提供一种可行的解决方案。

1,1,1,3,4,4,4-heptafluoro-3-(trifluoromethyl)-2-butanone (C5-PFK) gas has attracted widespread attention at home and abroad due to its excellent electrical insulation properties and good environmental protection properties. Preparing high-precision C5-PFK mixed gas and accurately detecting the mixing ratio is conducive to the scientific demonstration of C5-PFK mixed gas and minimizes potential power hazards. The FTIR experiment, combined with the B3LYP method for spectral theoretical calculation, was used to study the infrared spectral absorption characteristics of C5-PFK gas. For CO2 and micro-water gas that may exist in the test environment, the cross-interference analysis of spectral lines was carried out under the same conditions as temperature, pressure and optical path; The C5-PFK gas mixture ratio sensor was simulated and tested based on NDIR technology, and the overall design of the sensor hardware system was carried out. According to the output characteristics of the sensor, a BP neural network temperature compensation model is established, and the repeatability and indication error of the sensor are tested. The results show that the strong absorption peak positions of C5-PFK gas are 1 200, 1 262 and 1 796 cm-1, respectively, and the molecular theoretical calculation agrees with the gass measured infrared spectrum. Under the background of synthetic air, the absorbance of CO2 gas at 1 262 cm-1 position is 6.04×10-7, the influence factor of micro water peak area in 150 nm filter bandwidth is about 3.15×10-3, and the cross-interference of spectral lines can be ignored. It is feasible to realize mixing ratio detection at a 1 262 cm-1 position. The range tracks the optical path, and the sensor simulation test results show that the 6.5 mm optical path can realize the detection of the C5-PFK mixture ratio of 0~15%. The output characteristics of the sensor show that the value of the absorption variable SA/SB decreases with the increase in temperature, showing a nonlinear relationship. The maximum indication error of 10% C5-PFK/Air mixture before and after temperature compensation by the BP neural network algorithm is 29.23% and 1.29%, respectively, and the output absorption variable SA/SB value remains unchanged after compensation. The sensor repeatability test shows that the RSD is 0.27%, less than 3%. The linear fitting coefficient R2 of the sensor indication corresponding to different concentrations is 0.999, and the maximum indication error is 2.47%. In summary, the advantages of the detection method and its sensor in the detection range of C5-PFK gas mixture ratio, anti-interference ability and reliability are verified, and a feasible solution for detecting the mixture ratio of C5-PFK gas mixture electrical equipment is provided.