A Fundamental Study of Aerosol Filtration by Fibrous Filters in the Transition Flow Regime PDF Download

Author: Zhiqun Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 534

View

Book Description

Author: Hsu-Chi Yeh
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 538

View

Book Description

Author: Dominique Thomas
Publisher: Elsevier
ISBN: 008102116X
Category : Science
Languages : en
Pages : 228

View

Book Description
Filtration of aerosols is omnipresent in our daily lives, in areas as diverse as health, the protection of people and the environment, and air treatment inside buildings. However, the collection of particles within a filter media is not, contrary to popular belief, linked to a simple screen effect. The phenomena involved are much more complex and require the consideration of aerosol interactions, filter media and process conditions to select the best fiber filter for a given application. Aerosol Filtration, book for students, hygiene or process engineers, fibrous media manufacturers, designers, and filtration system suppliers or users addresses the filtration of aerosols in six chapters. These chapters cover physics and aerosol characterization, the fibrous media, and efficiency and filter clogging by solid or liquid aerosols, with special attention to the filtration of the nanoparticles. - Analyses the behavior of fibrous media against solid and liquid aerosols - Presents models of efficiency and pressure drop - Introduces computing elements for estimating the lifetime of filters - Provides guidance for designing filters and predicting their behavior over time

Author: Kvetoslav R. Spurny
Publisher: CRC Press
ISBN: 9780873718301
Category : Nature
Languages : en
Pages : 564

View

Book Description
Aerosols are generally associated with damaging effects to the ozone and human health, however, some aerosols enable productions of very clean, highly dispersed materials. Advances in Aerosol Filtration is dedicated to progress in aerosol science, presenting newly developed theories, filtration models, and novel applications of aerosol gas filtration. Topics include new filtration materials, filter testing methods, electrically enhanced filtration, mechanical and chemical filter resistivity, computational models, and much more. This book examines the history and development of aerosol filtration science and also considers research needs for the future.

Author: Benjamin James Mullins
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages :

View

Book Description
Abstract: This thesis examines the particle capture, fibre wetting and droplet flow processes within wet filters collecting solid and liquid aerosols and within filters collecting only liquid aerosols. The processes involved in this type of filtration were examined through a series of experiments and models developed to describe the behaviour of fibre/liquid systems. -- This work can be summarized in 4 categories: (1) The bounce and immediate re-entrainment of liquid and solid monodisperse aerosols under a stable filtration regime (pre cake formation) by wet and dry fibrous filters. In this work it was found that the solid particles generally exhibited a lower fractional filtration efficiency than liquid particles (of the same size), although this difference decreased in the smaller size fractions. However, for the wet filtration regime (each fibre of the filter was coated by a film of water), no significant difference in filtration efficiency was detectable between solid and liquid aerosols. Either the bounce effect of the particles is inhibited by the liquid film, or the filtration conditions in the wet filter are so different that the aerosol properties are less significant with respect to capture. (2) A microscopic study of the effect of fibre orientation on the fibre wetting process and flow of liquid droplets along filter fibres when subjected to airflow and gravity forces was conducted. The flow of the liquid collected by the fibres was observed and measured using a specially developed micro-cell, detailed in the thesis. The experimental results were compared to a theoretical model developed to describe the flow of droplets on fibres. The theory and experimental results showed a good agreement. A sensitivity analysis of the model was performed which showed the droplet radius to be the most significant parameter. The model has the potential to improve filter self-cleaning and minimise water use. (3) An experimental study of the capture of solid and liquid (oil) aerosols on fibrous filters wetted with water. Variable quantities of liquid irrigation were used, and the possibility for subsequent fibre regeneration after clogging or drying was also studied. It was found that self-cleaning (removal of solid aerosols by water) occurred even under heavily dust-laden conditions, and post evaporation of water. With the collection of oil aerosols on fibres wetted with water, a predominance of the barrel shaped droplet on the fibre was observed, with oil droplets displacing water droplets (if the oil and fibre combination created a barrel shaped droplet), creating various compound droplets of oil and water not previously reported in literature. (4) An extensive experimental investigation of the wetting processes of fibre/liquid systems during air filtration (when drag and gravitational forces are acting) has shown many important features, including droplet extension, oscillatory motion, and detachment from fibres as airflow velocity increases. The droplet oscillation is believed to be induced by the onset of the transition from laminar to turbulent flow as droplet size increases. To model such oscillation it was necessary to create a new conceptual model to account for the forces both inducing and preventing such oscillation. The agreement between the model and experimental results is satisfactory for both the radial and transverse oscillations.

Author: Gary S. Earnest
Publisher:
ISBN:
Category :
Languages : en
Pages : 442

View

Book Description

Author: R.C. Brown
Publisher: Pergamon
ISBN:
Category : Science
Languages : en
Pages : 300

View

Book Description
The need for clean air has probably never been greater. Many industrial employees need to avoid exposure to airborne particulates, while certain industrial processes demand clean air of exceptional quality. Medical and biological fields rely on sterile air, while filtration can improve air quality in offices, homes and all types of transport. Filters act in a variety of complex and subtle ways. Each chapter introduces its subject matter simply, before tackling the problem in greater depth. The book therefore provides an excellent basis for detailed study, but is also invaluable to anyone needing an overview of the subject.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

View

Book Description
The most common method of removing particles from a gas stream is via fibrous filters. However, most of the previous studies have been limited to systems consisting of rows of fibers (often in two-dimensional geometries) perpendicular to the flow direction. The current work is aiming to develop an understanding of the role of filter?s microstructure and manufacturing process. In the first part of this study, pressure drop and nanoparticle collection efficiency of lightweight spun-bonded media are simulated by solving the Navier-Stokes equations inside three-dimensional geometries resembling the microstructure of such media. These pressure drop and collection efficiencies showed a perfect agreement with experimental data. In the second part of this work, the influences of fiber length and compaction ratio of filter media on the pressure drop are discussed. Simulation data of staple fiber media have shown good agreement with Davies? empirical equation. Such an agreement indicates that, within the range of dimensions considered, the fiber length has no significant influence on the materials? through-plane permeability as long as the SVF remains constant. Our simulation results for nonwovens with different compaction ratios, together with our experimental data, indicate that pressure drop of the porous media increases with increasing the compaction ratio or temperature of the calender rolls. In the third part of this work, we presented our approach for modeling permeability of fibrous filters with bimodal fiber size distributions (referred to as bimodal filters in this context). The three-dimensional microstructures resembling bimodal filter media with random in-plane fiber orientation distribution were generated to compute their permeability constants. These results were compared with the previous analytical and numerical models as well as our experimental data. Here we concluded that there exists an area-weighted equivalent average diameter for each bimodal filter tha.

Author: Behzad Fardi
Publisher:
ISBN:
Category : Air filters
Languages : en
Pages : 444

View

Book Description

Author: Wade H. Shafer
Publisher: Springer Science & Business Media
ISBN: 1461534747
Category : Science
Languages : en
Pages : 421

View

Book Description
Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) * at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all con cerned if the printing and distribution of the volumes were handled by an interna tional publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Cor poration of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 34 (thesis year 1989) a total of 13,377 theses titles from 26 Canadian and 184 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this important annual reference work. While Volume 34 reports theses submitted in 1989, on occasion, certain univer sities do report theses submitted in previous years but not reported at the time.