Download or read book tude Num rique de L effet Des Tensioactifs Sur Le Transfert de Mati re Gaz liquide written by Kalyani Kentheswaran and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gas-liquid mass transfer is a topic of interest for industrial processes and multiphase reactors, water treatment being an application example. The dispersed two-phase flows are generally contaminated: surrounding impurities or surfactants adsorb to the interfaces and affect the surface tension. The Marangoni effect, resulting from surface tension gradients, was shown to decrease the rising velocity of a bubble to the one of a solid sphere of same size, for a fully covered interface. Regarding mass transfer, significant mass flux decrease in the presence of surfactants was experimentally observed. However, the impact of surfactants is not fully understood. In the present work, numerical investigation about the mass transfer rate around rising bubbles in liquid phases with surfactants is carried out, by means of direct numerical simulations. The main motivation of the present thesis is to provide complete models of the Sherwood number, depending on the degree of interface contamination.The direct numerical simulations are performed with the in-house code DIVA, based on the Level-Set and the Ghost Fluid methods, which are respectively used to capture the interface and the discontinuities across the interface. Numerical developments have been carried out to simulate the transport of surfactants in the bulk phase and along the bubble surface, by including bulk-interface adsorption/desorption fluxes. The Navier-Stokes equations are coupled with the Marangoni stress, taken into account through a jump condition on the tangential viscous stress across the interface. The transfer of a passive single species from the gas to the liquid is computed by an advection-diffusion equation, considering that resistance to transfer only lies in the liquid. Axisymmetric simulations are performed, in inertial regime of rising, by varying the different parameters of the problem (Reynolds, Marangoni, Schmidt numbers).The present thesis is divided into three parts. First, two parametric studies were carried out in the stagnant-cap regime (insoluble surfactants), characterized by the contamination angle formed by the advected surfactants at the bubble rear. (i) The first one focuses on a spherical bubble. A thorough analysis of the impact of surfactants on the maximal velocity of the fluid at the interface is presented, which is found to be a relevant parameter to quantify the mass transfer rate. A general scaling law is proposed to predict the global Sherwood number from a clean to a fully contaminated interface condition. (ii) The second one tackles the mass transfer around oblate bubbles. The obtained aspect ratio and drag coefficient in clean and fully contaminated conditions are in good agreement with existing correlations. The transition between these two extremes is studied, by analyzing the coupling between rise velocity and deformation. The impact of surfactants on the drag coefficient and the aspect ratio is investigated regarding the intensity of the local Marangoni stresses and the pressure distribution around the interface. Then, the mass transfer around the deformed bubble is quantified and found to follow the prediction proposed in (i) for a spherical bubble of same equivalent diameter. (iii) Finally, the impact of soluble surfactants on the bubble dynamics and mass transfer is considered, by analyzing the influence of the surfactant exchanges between bulk and interface, in both the stagnant cap and the uniformly retarded regime. The latter depend on the time scale ratio between the surfactant transfer process and surface convection. In the stagnant-cap regime, where surface convection is fast, the transient phase is found to be composed of a succession of quasi steady-states, leading to similar results as in (i). In the uniformly retarded regime, where the two time scales are of same order, the Marangoni effect is smaller but covers the whole interface. The tangential velocity at the interface determines the mass transfer rate.
Download or read book Transfert de mati re gaz liquide en milieux complexes written by Marupatch Jamnongwong and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: L'opération de transfert de matière gaz/liquide est une étape essentielle en génie desprocédés. Elle conditionne directement les performances des contacteurs gaz/liquide en représentantbien souvent l'étape limitant l'efficacité du procédé. L'objectif de cette étude est de proposer denouvelles investigations afin d'étudier l'effet de la présence dans l'eau pure, de certains composésgénéralement rencontrés dans les procédés biologiques, sur les coefficients de diffusion de l'oxygèneet de quantifier leurs conséquences sur les coefficients de transfert de matière côté liquide. Lescoefficients de diffusion de l'oxygène DO2 ont été mesurés dans diverses phases liquides contenant dusel (NaCl), du sucre (glucose) ou des tensio-actifs (laurylsulfate de sodium). Comparé à l'eau pure,des réductions de coefficient de diffusion DO2 ont été observées, la variation de DO2 avec laconcentration C de composé a été modélisée, elle dépend de la nature du composé ajouté. Ensuite,des expériences réalisées sur un train de bulles et sur les mêmes phases liquides ont permis ladétermination des coefficients de transfert de matière côté liquide kL. Quelle que soit la solutionaqueuse étudiée, une diminution des valeurs de kL est observée avec l'augmentation de C. Cesrésultats mettent en évidence que, même si les propriétés de l'eau pure (densité, viscosité, tensionsuperficielle) ne sont pas significativement modifiées par l'ajout de sels (NaCl), les coefficients detransfert de matière côté liquide kL peuvent être modifiés. Pour les solutions aqueuses de glucose, laréduction de kL avec DO2 est bien corrélée, et principalement due à la variation de viscosité avec laconcentration. Pour les solutions de tensio-actif, les nombres de Reynolds restent presque constantspour toutes les concentrations. Le seul responsable de la réduction du coefficient de transfert dematière côté liquide kL est donc le coefficient de diffusion de l'oxygène qui diminue avec laconcentration. La présente étude a clairement confirmé la nécessité de compléter et/ou rendre comptedes données liées aux coefficients de diffusion de l'oxygène DO2 et aux coefficients de transfert dematière côté liquide kL dans des milieux complexes (solution électrolytique, solution organique ettensioactif). Ces informations sont nécessaires pour décrire et modéliser correctement lesphénomènes de transfert de matière gaz/liquide.
Download or read book Principles and Practice of Variable Pressure Environmental Scanning Electron Microscopy VP ESEM written by Debbie Stokes and published by John Wiley & Sons. This book was released on 2008-12-22 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: Offers a simple starting point to VPSEM, especially for new users, technicians and students containing clear, concise explanations Crucially, the principles and applications outlined in this book are completely generic: i.e. applicable to all types of VPSEM, irrespective of manufacturer. Information presented will enable reader to turn principles into practice Published in association with the Royal Microscopical Society (RMS) -www.rms.org.uk
Download or read book Fundamentals of Latex Film Formation written by Joseph Keddie and published by Springer Science & Business Media. This book was released on 2010-02-18 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book has emerged out of our long-time research interests on the topic of latex film formation. Over the years we have built up a repertoire of slides used in conference presentations, short courses and tutorials on the topic. The story presented in this book has thereby taken shape as it has been told and re-told to a mix of academic and industrial audiences. The book presents a wide body of work accumulated by the polymer colloids community over the past five decades, but the selection of examples has been flavoured by our particular experimental interests and development of mathematical models. We intend the book to be a starting point for academic and industrial scientists beginning research on latex film formation. The emphasis is on fundam- tal mechanisms, however, and not on applications nor on specific effects of formu- tions. We hope that the book consolidates the understanding that has been achieved to-date in the literature in a more comprehensive way than is possible in a review article. We trust that the reader will appreciate the fascination of the topic.
Download or read book Cellular Automata Modeling of Physical Systems written by Bastien Chopard and published by Cambridge University Press. This book was released on 2005-06-30 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a self-contained introduction to cellular automata and lattice Boltzmann techniques. Beginning with a chapter introducing the basic concepts of this developing field, a second chapter describes methods used in cellular automata modeling. Following chapters discuss the statistical mechanics of lattice gases, diffusion phenomena, reaction-diffusion processes and non-equilibrium phase transitions. A final chapter looks at other models and applications, such as wave propagation and multiparticle fluids. With a pedagogic approach, the volume focuses on the use of cellular automata in the framework of equilibrium and non-equilibrium statistical physics. It also emphasises application-oriented problems such as fluid dynamics and pattern formation. The book contains many examples and problems. A glossary and a detailed bibliography are also included. This will be a valuable book for graduate students and researchers working in statistical physics, solid state physics, chemical physics and computer science.
Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer. This book was released on 1985-03 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 1 957, 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 28 (thesis year 1 983) a total of 10,661 theses titles from 26 Canadian and 197 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 28 reports theses submitted in-1983, on occasion, certain univer sities do report theses submitted in previous years but not reported at the time.
Download or read book Technology and Solvents for Extracting Oilseeds and Nonpetroleum Oils written by Peter J. Wan and published by The American Oil Chemists Society. This book was released on 1997 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book brings together current information on technology and solvents for extracting oilseeds. The editors hope that this monograph will serve as a useful reference for the managers and engineers in oil extraction and its allied industries and a starting point for researchers in searching for the optimum solvent for extraction of any given oil-bearing materials.
Download or read book Guide to the International Registration of Marks under the Madrid Agreement and the Madrid Protocol written by World Intellectual Property Organization and published by WIPO. This book was released on 2019-09-11 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Guide is primarily intended for applicants and holders of international registrations of marks, as well as officials of the competent administrations of the Member States of the Madrid Union. It leads them through the various steps of the international registration procedure and explains the essential provisions of the Madrid Agreement, the Madrid Protocol and the Common Regulations.
Download or read book The Genus Alexandrium Halim Dinoflagellata written by Enrique Balech and published by . This book was released on 1995 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Per and polyfluorinated substances in the Nordic Countries written by Stefan Posner and published by Nordic Council of Ministers. This book was released on 2013-06-19 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Tema Nord report presents a study based on open information and custom market research to review the most common perfluorinated substances (PFC) with less focus on PFOS and PFOA. The study includes three major parts:1) Identification of relevant per-and polyfluorinated substances and their use in various industrial sectors in the Nordic market by interviews with major players and database information; 2) Emissions to and occurence in the Nordic environment of the substances described in 1); 3) A summary of knowledge of the toxic effects on humans and the environment of substances prioritized in 2); There is a lack of physical chemical data, analystical reference substances, human and environmental occurrence and toxicology data, as well as market information regarding PFCs other than PFOA and PFOS and the current legislation cannot enforce disclosure of specific PFC substance information.
Download or read book Population Environment and Development written by UN. Population Division and published by United Nations Publications. This book was released on 2001 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: The general trends of rapid population growth, sustained but uneven economic improvement, and environmental degradation, are well known. Population and development policies are vital components of action needed to ensure sustainable development and to safeguard the environment. The topics investigated in this report include: the evolution of population and the environment at major UN conferences; trends in population, environment and development; government views; health, mortality, fertility and the environment; urbanization.
Download or read book Scientific Canadian Mechanics Magazine and Patent Office Record written by Canada. Patent Office and published by . This book was released on 1966-03 with total page 1070 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Air Pollution Modeling and its Application XXIV written by Douw G. Steyn and published by Springer. This book was released on 2016-02-10 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current developments in air pollution modelling are explored as a series of contributions from researchers at the forefront of their field. This newest contribution on air pollution modelling and its application is focused on local, urban, regional and intercontinental modelling; data assimilation and air quality forecasting; model assessment and evaluation; aerosol transformation. Additionally, this work also examines the relationship between air quality and human health and the effects of climate change on air quality. The work is comprised of selected papers presented at the 34th International Technical Meeting on Air Pollution Modelling and its Application held in Montpellier, France in 2015. The book is intended as reference material for students and professors interested in air pollution modelling at the graduate level as well as researchers and professionals involved in developing and utilizing air pollution models.
Download or read book Agrimonde Scenarios and Challenges for Feeding the World in 2050 written by Sandrine Paillard and published by Springer. This book was released on 2016-09-03 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: How will the world be able to feed close to 9 billion people in 2050 and still maintain the ecosystems? In this perspective, INRA and CIRAD launched the initiative, in 2006, to develop a foresight project for analysing issues pertaining to the world's food and agricultural systems on the 2050 timeline. This book provides a synthetic presentation of the main conclusions that this foresight project has yielded. First, it recapitulates the main statistical references for the period 1961 to 2003, before going on to describe the Agribiom simulation tool used to calculate food biomass resource use balances. Two scenarios on the 2050 timeline are then considered: Agrimonde GO is a trend-based scenario that bets on economic growth to feed the world, in a context where environmental protection is not a priority; in contrast, the idea in Agrimonde 1 is to feed the world while preserving its ecosystems.
Download or read book Global Soil Security written by Damien J. Field and published by Springer. This book was released on 2016-11-01 with total page 454 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the concept of soil security and its five dimensions: Capability, Capital, Condition, Connectivity and Codification. These five dimensions make it possible to understand soil's role in delivering ecosystem services and to quantify soil resource by measuring, mapping, modeling and managing it. Each dimension refers to a specific aspect: contribution to global challenges (Capability), value of the soil (Capital), current state of the soil (Condition), how people are connected to the soil (Connectivity) and development of good policy (Codification). This book considers soil security as an integral part of meeting the ongoing challenge to maintain human health and secure our planet's sustainability. The concept of soil security helps to achieve the need to maintain and improve the world’s soil for the purpose of producing food, fiber and freshwater, and contributing to energy and climate sustainability. At the same time it helps to maintain biodiversity and protects ecosystem goods and services.
Download or read book In Silico Methods for Predicting Drug Toxicity written by Emilio Benfenati and published by Humana. This book was released on 2023-03-08 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This fully updated book explores all-new and revised protocols involving the use of in silico models, particularly with regard to pharmaceuticals. Divided into five sections, the volume covers the modeling of pharmaceuticals in the body, toxicity data for modeling purposes, in silico models for multiple endpoints, a number of platforms for evaluating pharmaceuticals, as well as an exploration of challenges, both scientific and sociological. Written for the highly successful Methods in Molecular Biology series, chapters include the kind of detail and implementation advice necessary for successful results. Authoritative and comprehensive, In Silico Methods for Predicting Drug Toxicity, Second Edition aims to guide the reader through the correct procedures needed to harness in silico models, a field which now touches a wide variety of research specialties.
Download or read book Molluscan Shellfish Safety written by Gilbert Sauvé and published by Springer Science & Business Media. This book was released on 2013-08-15 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a time of rapid climatic, industrial and technological changes in molluscan shellfish producing and exporting regions, it is of the utmost importance to keep a keen eye on developing trends. This collection of recent research in molluscan shellfish safety, risk assessment, risk management, regulation and analytical methods presented at the 8th ICMSS (International Conference on Molluscan Shellfish Safety) offers valuable insights in the latest scientific findings. Dans le contexte actuel de changements climatiques, industriels et technologiques rapides dans les régions qui produisent et qui exportent des mollusques, il est essentiel de rester à l’affût des nouvelles tendances. Ce recueil des récents travaux de recherche dans les domaines de la salubrité des mollusques, des évaluations des risques, de la gestion des risques, de la réglementation et des méthodes d’analyse présentés lors de la 8e Conférence internationale sur la salubrité des coquillages (ICMSS) vous aidera à le faire.
