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Etude physico-chimique de la formation et de l'évolution des particules dans la ligne d'échappement des véhicules : Modélisation et expérimentation
| Content Provider | Semantic Scholar |
|---|---|
| Author | Thi, Nguyen Xuân, Thanh |
| Copyright Year | 2005 |
| Abstract | Particle emissions from vehicles, especially those equipped with diesel engines, have become a focus of attention because of these potential adverse effects on human health. Indeed, fine particles with size lower than 2,5 μm are likely to penetrate deeply in the respiratory system and to release toxic products. Therefore, the vehicle manufacturers and oil companies need precise information concerning particle formation and evolution. The number densities and size distribution of particles emitted by the vehicles has been subject to several determinations, however, the methodologies used, the tested vehicles and the operating conditions are so different from one study to another, that it is very difficult to compare the results and to draw definitive conclusions. Numerical modeling of particle formation and evolution can be of great help to understand which of the different parameters have a great influence on the processes. In particular, it appeared important to test a certain number of assumptions concerning the particle formation, i.e. the nucleation (conversion gas-liquid) of the sulphuric acid-water mixture as well as the possible role of some hydrocarbons on particle growth. In this work, a modeling approach has been developed to explain particle formation and evolution. The model takes into account the various fundamental phenomena of aerosol formation including nucleation (homogeneous and heterogeneous on soot particles), growth by condensation, coagulation etc. In the same way, the variations of temperature and concentration profiles along the exhaust and the sample lines have been modeled, and this includes the presence of the catalyst and particle filter. We have been able to demonstrate that liquid aerosols could only appear after dilution of the exhaust gas, in the sample line. The model has been validated, successfully, by comparison with the results of measurement campaigns. The sensitivity studies allow to evaluate the influence of the parameters "fuel" (sulphur content), "motor" (speed, fuel consumption,...), and "conditions of measurements" (temperature, dilution ratio, humidity, residence time,...) on the formation of exhaust particles. This work has increased our knowledge on particle formation and evolution and lead to a better interpretation of the experimental results on particle measurements. It also provides a tool able to analyze the parameters that have a major influence on the level of particle emissions. Finally, the model developed in this study may be of great help to the legislator in order to propose possible future standards. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://tailieuso.udn.vn/bitstream/TTHL_125/7143/2/NguyenThiThanhXuan.TT.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
