Heterogeneous Nucleation of N-Butanol and Water Vapor on Nanoparticles
| Autor: | Hung-Hsu Chen, 陳泓旭 |
|---|---|
| Rok vydání: | 2002 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 90 Nano solid particles are one of important contributors to air pollution. These particles have long airborne lifetimes largely responsible for reduced visibility through urban air and possess potential health hazard. The physical processes involved in the heterogeneous nucleation of supersaturation vapor on of charge particles are not fully understood. A systematic study on the heterogeneous nucleation of vapor on TiO2 and SiO2 charged particles is proposed employing a flow cloud chamber (FCC). Supersaturated water or n-butanol vapor condenses onto the particles, which grow up to larger sizes and settle out with appreciable velocities. The critical supersaturation required for a nucleation rate of one on a particle is obtained from the measurement of the removal efficiency a function of supersaturation in conjuction with a theoretical analysis. The experimental results show that there is no charge effect and sign preference on the critical supersaturation for SiO2 particles with a diameter larger than 15nm. This experimental employ a new nanoparticle generation system, i.e. electrospray system, to product nanoparticles. Because of defects in the system design, the electrospray system didn’t work as expected. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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