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Mesure de particules cylindriques par anemometrie phase doppler
Abstracts
SOLID AND LIQUID AEROSOL PARTICLE FILTER MATERIAL PERFORMANCE:
1361
LOADING EFFECTS AN EXPERIMENTAL
ON FIBROUS STUDY
K. L. Scurrah and J. I. T. Stenhouse Aerosol
Technology
Group,
Department of Chemical Engineering, Loughborough Loughborough, Leics, LEll 3TU U.K.
University,
Ashby
Road,
Prefilters are used in a variety of domestic and industrial applications in order to remove nuisance dusts and oils. Often, the prefilter material will require replacing after a period of use, so it is economically important to consider the lifetime of filter materials in addition to their loading behaviour. When fibrous filters are loaded with solid aerosol particles, the deposited particles act as collection sites for incoming solid particles and dendritic structures are formed. These structures cause the collection efficiency and pressure drop across the filter to increase. Ultimately, the filter becomes “clogged”, where it becomes full of solid particles, and a cake builds up on the filter surface. As the pressure drop across this cake is usually very high, it is common practice to dispose of the media at this stage. In contrast, loading fibrous filters with liquid aerosol particles generates an interesting response. During the initial stages of loading, both the efficiency and pressure drop increase in a similar way as found in solid particle loading. Thereafter, the behaviour becomes much more complex, due to the fact that liquids flow more easily than solids. As the filter is loaded further, collected liquid particles coalesce on the filter fibres to form liquid bridges, which act as additional collection sites and enhance the filter performance. After further loading, the filter never becomes “clogged”, but reaches an equilibrium condition where the filter pressure drop and collection efficiency are constant. Additionally, liquid particle collection, drainage, internal relocation and particle re-entrainment exist during this operating regime and some types of fibrous filters can be operated for extended periods, as well as be cleaned and re-used. This paper reports on experimental investigations into the loading behaviour of fibrous filters under solid or liquid aerosol particle loads, highlighting both the similarities and differences between the two systems.
MESURE DE PARTICULES CYLINDRIQUES ANEMOMETRIE PHASE DOPPLER
PAR
N. Gauchet, T. Girasole, K. F. Ren, G. Grkhan and G. Gouesbet Laboratoire
d’EnergCtique
des Systtmes
et Pro&d& INSA de ROUEN, URA.CNRS.230, Mont-Saint-Aignan CBdex, France
CORIA,
B.P. O&76131,
The extension of Phase Doppler Anemometry to the measurement of cylinder diameters is studied with a rigorous approach based on the resolution of Maxwell’s equations. The differences induced by the choice of the model of the incident beam description are shown. Then, the properties of different possible geometries are compared.
DEVELOPPEMENT DE TECHNIQUES POUR MESURER LA DISTRIBUTION EN DIMENSION DES PRODUITS DE FILIATION A VIE COURTE DU RADON-222 DEVELOPMENT OF TECHNIQUES TO MEASURE THE SIZE DISTRIBUTION OF SHORT LIVED RADON-222 DECAY PRODUCTS C. Huet,* G. Tymen,* N. Michielsen+ and D. Boulaud+ * Laboratoire +Institut
de Recherches
Appliquies
Atmosphkre, Hydrosphkre, FacultC des Sciences et Techniques, B.P. 809, 29285 Brest Cedex de Protection et de Stireti NucleBire, Laboratoire de Physique et MCtrologie des Akrosols, IPSN/CEA Bdt 389, CE Saclay, 91191 Gif-Sur-Yvette Cedex
The size distribution of inhaled radon short lived decay products 218Po, 214Pb, 214Bi, 2’4Po has to be known in domestic conditions in order to determine the dose received by any individual. Usually two major fractions are considered: the unattached one represents particles whose size lies from 0.5 nm to a few nanometers and the attached compound with size going from 5 nm to a few micrometers. The last developments concerning the dosimetric models showed the importance of a better knowledge of the size distribution over the whole spectrum. The Diffusional and Inertial Spectrometer (SD12001), conceived by IPSN, which consists in a four stages impactor followed by five parallel granular beds, is able to collect particles from 10 nm to 10 pm. The concentrations of each short lived decay product are determined by alpha-counting with Time Evolved Least squares (TELS) method. The size distributions are reconstructed by using inversion methods (EVE, Twomey). For the nanometric compound, an annular diffusion channel is used: (1) equipped with a solid state alpha track detector, it is possible
SOLID AND LIQUID AEROSOL PARTICLE FILTER MATERIAL PERFORMANCE:
1361
LOADING EFFECTS AN EXPERIMENTAL
ON FIBROUS STUDY
K. L. Scurrah and J. I. T. Stenhouse Aerosol
Technology
Group,
Department of Chemical Engineering, Loughborough Loughborough, Leics, LEll 3TU U.K.
University,
Ashby
Road,
Prefilters are used in a variety of domestic and industrial applications in order to remove nuisance dusts and oils. Often, the prefilter material will require replacing after a period of use, so it is economically important to consider the lifetime of filter materials in addition to their loading behaviour. When fibrous filters are loaded with solid aerosol particles, the deposited particles act as collection sites for incoming solid particles and dendritic structures are formed. These structures cause the collection efficiency and pressure drop across the filter to increase. Ultimately, the filter becomes “clogged”, where it becomes full of solid particles, and a cake builds up on the filter surface. As the pressure drop across this cake is usually very high, it is common practice to dispose of the media at this stage. In contrast, loading fibrous filters with liquid aerosol particles generates an interesting response. During the initial stages of loading, both the efficiency and pressure drop increase in a similar way as found in solid particle loading. Thereafter, the behaviour becomes much more complex, due to the fact that liquids flow more easily than solids. As the filter is loaded further, collected liquid particles coalesce on the filter fibres to form liquid bridges, which act as additional collection sites and enhance the filter performance. After further loading, the filter never becomes “clogged”, but reaches an equilibrium condition where the filter pressure drop and collection efficiency are constant. Additionally, liquid particle collection, drainage, internal relocation and particle re-entrainment exist during this operating regime and some types of fibrous filters can be operated for extended periods, as well as be cleaned and re-used. This paper reports on experimental investigations into the loading behaviour of fibrous filters under solid or liquid aerosol particle loads, highlighting both the similarities and differences between the two systems.
MESURE DE PARTICULES CYLINDRIQUES ANEMOMETRIE PHASE DOPPLER
PAR
N. Gauchet, T. Girasole, K. F. Ren, G. Grkhan and G. Gouesbet Laboratoire
d’EnergCtique
des Systtmes
et Pro&d& INSA de ROUEN, URA.CNRS.230, Mont-Saint-Aignan CBdex, France
CORIA,
B.P. O&76131,
The extension of Phase Doppler Anemometry to the measurement of cylinder diameters is studied with a rigorous approach based on the resolution of Maxwell’s equations. The differences induced by the choice of the model of the incident beam description are shown. Then, the properties of different possible geometries are compared.
DEVELOPPEMENT DE TECHNIQUES POUR MESURER LA DISTRIBUTION EN DIMENSION DES PRODUITS DE FILIATION A VIE COURTE DU RADON-222 DEVELOPMENT OF TECHNIQUES TO MEASURE THE SIZE DISTRIBUTION OF SHORT LIVED RADON-222 DECAY PRODUCTS C. Huet,* G. Tymen,* N. Michielsen+ and D. Boulaud+ * Laboratoire +Institut
de Recherches
Appliquies
Atmosphkre, Hydrosphkre, FacultC des Sciences et Techniques, B.P. 809, 29285 Brest Cedex de Protection et de Stireti NucleBire, Laboratoire de Physique et MCtrologie des Akrosols, IPSN/CEA Bdt 389, CE Saclay, 91191 Gif-Sur-Yvette Cedex
The size distribution of inhaled radon short lived decay products 218Po, 214Pb, 214Bi, 2’4Po has to be known in domestic conditions in order to determine the dose received by any individual. Usually two major fractions are considered: the unattached one represents particles whose size lies from 0.5 nm to a few nanometers and the attached compound with size going from 5 nm to a few micrometers. The last developments concerning the dosimetric models showed the importance of a better knowledge of the size distribution over the whole spectrum. The Diffusional and Inertial Spectrometer (SD12001), conceived by IPSN, which consists in a four stages impactor followed by five parallel granular beds, is able to collect particles from 10 nm to 10 pm. The concentrations of each short lived decay product are determined by alpha-counting with Time Evolved Least squares (TELS) method. The size distributions are reconstructed by using inversion methods (EVE, Twomey). For the nanometric compound, an annular diffusion channel is used: (1) equipped with a solid state alpha track detector, it is possible