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|Title:||Tortuosity variation in a low density binary particulate bed|
|Authors:||Dias, Ricardo P.|
Teixeira, José A.
Binary spheres packing
|Citation:||Dias, Ricardo P.; Teixeira, José A.; Mota, Manuel; Alexander, Yelshin (2006) - Tortuosity variation in a low density binary particulate bed. Separation and Purification Technology. ISSN 1383-5866. p.180-184|
|Abstract:||The importance of particle size ratio and particle composition in the properties of a mixed bed is well known. Nevertheless, the dependence of the bed channel tortuosity T on the porosity ε in the form T=1/εn, where n is assumed to be a constant, shows that the value of n depends on the properties of the packed bed. For loose packing, experimental data for binary mixtures of glass beads of a size ratio from 1 up to 53.8 was analysed in terms of porosity, tortuosity and permeability. The packing procedure was performed without intensive compacting methods e.g. vibration, etc. Obtained results show that the parameter n is a function of the volume fraction of large particles xD and, for spherical particles, lies in the range 0.4–0.5. The explanation for this variation is (1) a distortion effect on the small particles arrangement occurring near the large particle surface; (2) in the region of minimum porosity, near contact points of large particles, the occurrence of dead zones that are free of small particles. A relationship accounting for this effect is proposed that may be useful for the analysis of transport phenomena in granular bed filters, chromatographic columns, etc.|
|Appears in Collections:||DTQB - Artigos em Revistas Indexados ao ISI/Scopus|
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