Abstract:

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.

Key words: hydrogen flame ionization detector, total hydrocarbons, micro-current amplifier circuit, standard curve method