5 resultados para Particle retention

em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"


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The aim of this work was the development of miniaturized structures useful for retention and/or selection of particles and viscous substances from a liquid flow. The proposed low costs structures are similar to macroscopic wastewater treatment systems, named baffles, and allow disassemble. They were simulated using FEMLAB 3.2b package and manufactured in acrylic with conventional tools. Tests for retention or selection of particles in water or air and viscous fluids in water were carried out. Either in air or water particles with 50 mu m diameter will be retained but not with 13 mu m diameter. In aqueous flow, it is also possible the retention of viscous samples, such as silicone 350 cSt. The simulated results showed good agreement with experimental measurements. These miniaturized structures can be useful in sample pretreatment for chemical analysis and microorganism manipulation. (C) 2007 Elsevier B.V. All rights reserved.

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The designs of filters made by granular material or textile are mainly based on empirical or semi empirical retention criteria according to Terzaghi proposal, which compares particle diameter of the soil base with the filter porous spaces. Silveira in 1965, proposed one rational design retention criteria based on the probability of a particle from the soil base, carried by one dimensional flow, be restrained by the porous of the filter while trying to pass through its thickness. This new innovating theory, besides of being very simple, it is not frequently used for granular filters since the necessary parameters for the design has to be determine for each natural material. However, for textile this problem no longer exists because it has quality control during manufacturing and the necessary characteristics properties of the product are specify in the product catalog. This work presents one adaptation of the Silveira theory for textile filters and the step-by-step procedure for the determination of the characteristics properties of the textile products necessary for the design. This new procedure permits the determination of the confiability level of retention that one specific particle diameter form the soil base has for one specified textile. One complete example is presented to demonstrate the simplicity of the method proposed and how the textile characteristics are obtained.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)