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| Titel: |
Very High Volume Aerosol Sampling with a Novel Drum Centrifuge |
| Auteur: |
Hollander, W. Morawietz, G. Pohlmann, G. Wolter, H. Gallily, I. Cohen, A. H. |
| Verschenen in: |
Aerosol science and technology |
| Paginering: | Jaargang 7 (1987) nr. 1 pagina's 67-77 |
| Jaar: |
1987 |
| Inhoud: |
For chemical analysis of trace compounds, comparatively large amounts of dust have to be collected. If good time resolution is required, very high sampling flow rates are mandatory. The operating principle of the drum centrifuge built to cope with these requirements is based on particle deposition on the inner surface of a porous rotating drum. Due to the rotation, a pressure gradient draws the aerosol into the bore of the axis and from there radially outward through a number of holes into the drum. The aerosol then moves to the periphery of the double-walled drum, which consists of two 0.15-mm-thick metal sheets with 1-mm spacing. Each of these metal sheets is perforated by several rows of small slits resulting in porosity of 16%. The slits in the inner and outer sheet are displaced, so that the particles will be strongly deflected on their way out of the rotating drum. Under the combined action of centrifugal forces and strong streamline deflection in the displaced slits of the two thin-walled drums, the particles are deposited. Flow rate as a function of rpm and collection efficiency as a function of particle size were determined experimentally. For simplicity, only the flow field of two (nonrotating) displaced slits was mathematically analyzed. The resulting 2-D solution of the Navier-Stokes equation was used for deterministic limiting trajectory calculations in the case of large particles. Diffusional motion of small particles was allowed for by Monte Carlo trajectory calculation. The calculated deposition efficiencies agree satisfactorily with the experimental results. At 3000 rpm a flow rate of 1200 m3/hr and efficiencies of 91% for 2.1-μm particles, 75% for 0.6-μm particles, and 48% for 0.04-μm particles were obtained. For easy extraction of the collected particulate matter, the device is equipped with an ultrasonic cleaning bath. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 11 van 11 gevonden artikelen
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