汽油車引擎廢氣揮發性有機物成份及光化反應潛勢
| Autor: | 何文淵 |
|---|---|
| Rok vydání: | 1999 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 87 This research is a simulation of the motion of cars using "car body dynamometer", which follows the United States Federal Test Procedure (FTP-75). We collect the emissions of car engines under various motion modes. The composition and concentrations of all volatile organic pollutants are analyzed qualitatively and quantitatively. In addition, we can pick some seriously polluting cars by remote sensor and test them simultaneously with the dynamometer before and after tuning and repair, in order to understand how those cars improve their pollution emissions. The factors influencing the emission of volatile organic considered in the experiment including the age of cars, catalyst and types of fuel. We calculated the VOCs emission coefficients and translate them into the strength of photo reaction with the maximum incremental reactivity index, therefore we can estimate the potential of ozone formation from VOCs emissions of car engines. The results shows huge differences in the concentrations of all pollutants in the emission of old and new cars. The THC emission coefficients of new cars, cars in use, and high-polluting cars are 0.15±0.06, 0.17±0.06, and 2.39±1.30 g/km respectively. The CO emission coefficients are 1.11±0.71, 1.56±0.62, and 17.27±9.14 g/km. The NOx emission coefficients are 0.15±0.06, 0.17±0.06, and 2.39±1.30 g/km. New cars have the lowest emission coefficients for all pollutants and high-polluting cars have the highest. The components of major VOCs in emissions of car engines include toluene, benzene, and m,p-xylene. Other components with significant emission coefficients include 1,2,4-trimethylbenzene, 2-methylpentane, isopentane, propylene and o-xylene. From the comparison of different types of fuel, cars using 92 non-lead gasoline have higher emission concentrations and coefficients than cars using 95 non-lead gasoline. The older the cars, the higher their emission concentrations and coefficients. Cars over 5 years old and 70,000 kilometers mileage are the most likely candidates of high-polluting cars. In the three phases, there are different emission features of automobiles. Cold start transient phase has the highest VOCs emission concentrations and coefficients, hot start transient phase the next, and stabilized phase the lowest. In the comparison of moving conditions, moving at 40 km/hr steady speed has the highest emission concentration and coefficients, while the decelerating condition has the lowest. The results indicates that the emission of high-polluting cars is equivalent to the summation of 15 cars in use. Tuning and repairing cannot help much in pollution which comes form emission of car engines. Further study about tuning and repairing is recommended. The study of MIR index shows the production of ozone by car engines as follows: new cars produce 308.5 mg (O3) / km, cars in use produce 328.2 mg (O3) / km, high-polluting cars produce 4977.5 mg (O3) / km. The major components in emission of car engines that lead to ozone production are toluene, m,p-xylene and 1,2,4-trimethylbenzene for new cars; propylene, 1-butene and toluene for cars in use; and 1,2,4-trimethylbenzene, propylene, and toluene. The above components with high ozone contribution are those with high emission coefficients and strong photo reactivity. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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