基于FID的机动车尾气THC测量模块设计与对比实验

机动车排放的总碳氢化合物（total hydrocarbons, THC）是造成雾霾、光化学烟雾的重要原因，在城市大气污染的调查和影响人类健康的研究中，THC是必须的监测目标之一。着重开展了基于氢火焰离子化检测（hydrogen flame ionization detector, FID）的机动车尾气THC测量系统的设计和对比实验。主要介绍了FID测量THC的工作原理，根据FID的测量原理设计了机动车尾气THC测量模块。并根据离子化信号检测需求设计了微电流放大电路，满足大范围、高精度微电流信号检测的要求，获得了检测器对THC的响应峰信号。还对测量得到的THC色谱峰信号进行定性和定量的分析，通过标准曲线法计算了THC的浓度。最后结合美国的SENSORS-FID THC分析仪开展了对比实验，结果表明研发的THC测量模块检测的浓度偏高，测量偏差约为4.44%~8.43%，判断此系统误差主要为O2峰干扰。

Design and Comparative Experiment of Vehicle Exhaust THC Measurement System Based on FID

Total hydrocarbons (THC) of vehicle emissions is the major cause of haze and photochemical smog, so THC monitoring must be one of the goals in the investigation of urban air pollution and research of effects on human health. The design of the THC measurement system based on hydrogen flame ionization detector (FID) for vehicle exhaust is developed and comparative experiments are carried out. The working principle of the FID for measuring THC is introduced, and the THC measurement module of vehicle exhaust is designed according to the measuring principle of FID. A micro-current amplifier circuit is designed for detecting the ion signals to meet a wide range, high-precision and micro-current signal testing requirements, and the peak signal of the THC is obtained. Moreover, the THC peak signals are analyzed qualitatively and quantitatively. The concentration of the THC are calculated by standard curve method. The comparative experiments are carried out by using SENSORS-FID THC analyzer of the United States, and the results show that the measurements of the THC measurement module is higher, and the measurement error is about 4.44% ~ 8.43%, this systematic error is primarily caused by oxygen peak interference.