Deposition of nanosized particles in cylindrical tubes under laminar and turbulent flow conditions
Résumé
There are few studies of deposition of nanoparticles due to di$culties in their generation and size measurement. These di$culties can be overcome by the use of radioactive nanoparticles (Po). This aerosol is obtained with a constant production rate from radon decay, and its concentration is determined using nuclear measurement techniques. We present an experimental and numerical study of Po deposition in laminar and turbulent tube #ows, in order to validate the appropriated theories. For laminar #ows, we observe a better correlation between our experimental and numerical results, as these take into account, unlike analytical theories, all the phenomena occurring. For turbulent #ows, the theories which are the most suitable are those of Wells and Chamberlain (1967, Brit. J. Appl. Phys. 18, 1793}1799) and Friedlander (1977, Smoke, Dust and Haze, Wiley, New York). Our experimental results show that an unexpected surface e!ect on nanoparticles deposition can be observed, even for a hydraulically smooth surface. We also assessed the in#uence of surface roughness on nanoparticle deposition experimentally. Unexpectedly, an in#uence of surface texture on the deposition rate was observed, although all tube surfaces were hydraulically smooth. This could be explained by a di!usion process.