The Study On The Pretreatment Method And Emission Characteristics Of Non-methane Organic Gas In Motor Vehicles

In recent years,with the number of motor vehicles increasing,the environmental impact caused by automobile exhaust emissions is also expanding,and our health and ecological environment are further threatened.In order to control the emission of vehicle exhaust pollutants,relevant laws and regulations had been issued by the governments of various countries to control them.As the world’s most stringent region for car emission requirements,in the CF/LEV plan of 1994,non-methane organic gas(NMOG)have be already mentioned by california and its emission values have also be stipulated.Although in the draft of Beijing Ⅵ emission standards,the concept of NMOG is described for the first time and the emission value is also stipulated,but meanwhile the detection methods of NMOG and the emission characteristics of vehicle have not been researched.Based on this background,the method of NMOG detection is mainly analyzed and optimized by this paper.Then,according to the selected analysis method,the emission characteristics and influencing factors of vehicle NMOG are studied.The specific research work is as follows:1、For carbonyl compounds,a tail gas sampling device is designed based on the DNPH derivatization method.The sampling volume should be selected and the arrangement of sampling tubes can be adjusted according to different driving cycles.And then the penetrability and extraction efficiency of DNPH tube are tested and measured.13 aldehydes and ketones are analyzed by high performance liquid chromatography(HPLC).According to the actual conditions of the laboratory,the chromatographic column,detection wavelength,detection temperature,mobile phase,flow velocity and other analytical conditions are selected to determine the best analysis conditions.Then the standard curves of 13 aldehydes and ketones are established and the samples are analyzed by this method.In order to analyze the reliability of the method,the recovery and precision of the analytical method are determined.For the measurement of non methane hydrocarbons,according to the requirements of the CHINA Ⅴ and CHINA Ⅵ Emission Standard,the GC-FID detection method is used to detect and analyze the collected exhaust gas.2、The emission test of vehicles with different driving cycles,different emission standards and different fuel states is carried out,and the emission characteristics of vehicle NMOG are analyzed;The NMOG emission data are collected by experiments with different test temperatures,different aftertreatment devices and different loads,and then the influence of test temperature,aftertreatment device and load on emission is analyzed.3、By collecting a series of emission data of non-methane hydrocarbons(NMHC)and NMOG,the curve fitting is carried out,and the estimation formulas of NMOG under NEDC or WLTC driving cycles are obtained,and the error analysis and verification are also carried out.