Phase Inversion of Liquid-liquid Dispersions Produced by Shear Or Turbulence PDF Download
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Author: Irini Efthimiadu
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: Irini Efthimiadu
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: H.N. Stein
Publisher: CRC Press
ISBN: 1000148556
Category : Science
Languages : en
Pages : 268
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Book Description
This work details the preparation of dispersions in liquids. It sets out to bridge the gap in information for the chemist who is not applications oriented and the chemical engineer who needs to solve problems in the field based on theoretical methods of dispersions of solids, liquids and gases. Insights are provided into many topics, including the transportation and handling of finely divided soils or highly viscous liquids; the reactions between reactants dissolved in immiscible phases; the formation of porous materials; and filtration.
Author: K. H. Ngan
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
This thesis presents the experimental and theoretical investigations on the development of phase inversion in horizontal pipeline flow of two immiscible liquids. It aims to provide an understanding on the flow development across the phase inversion transition as well as the effect on pressure drop. Experimental investigation on phase inversion and associated phenomena were conducted in a 38mm I.D. liquid pipeline flow facility available in the Department of Chemical Engineering at University College London (UCL). Two sets of test pipelines are constructed using stainless steel and acrylic. The inlet section of the pipeline has also been designed in two different configurations - (1) Y-junction inlet to allow dispersed flow to be developed along the pipeline (2) Dispersed inlet to allow formation of dispersion immediately after the two phases are joined. Pressure drop along the pipeline is measured using a differential pressure transducer and is studied for changes due to redistribution of the phases during inversion. Various conductivity probes (ring probes, wire probes, electrical resistance tomography and dual impedance probe) are installed along the pipeline to detect the change in phase continuity and distribution as well as drop size distribution based on the difference in conductivity of the oil and water phases. During the investigation, the occurrence of phase inversion is firstly investigated and the gradual transition during the process is identified. The range of phase fraction at which the transition occurs is determined. The range of phase fraction becomes significantly narrower when the dispersed inlet is used. The outcome of the investigation also becomes the basis for subsequent investigation with the addition of glycerol to the water phase to reduce the interfacial tension. Based on the experimental outcome, the addition of glycerol does not affect the inversion of the oil phase while enhancing the continuity of the water phase. As observed experimentally, significant changes in pressure gradient can be observed particularly during phase inversion. Previous literatures have also reviewed that phase inversion occurs at the maximum pressure gradient. In a horizontal pipeline, pressure gradient is primarily caused by the frictional shear on the fluid flow in the pipe and, in turn, is significantly affected by the fluid viscosities. A study is conducted to investigate on the phase inversion point by identifying the maximum mixture viscosity (i.e. maximum pressure gradient) that an oil-in-water (O/W) and water-in-oil (W/O) dispersion can sustain. It is proposed that the mixture viscosity will not increase further with an increase in the initial dispersed phase if the inverted dispersion has a lower mixture viscosity. This hypothesis has been applied across a wide range of liquid-liquid dispersion with good results. This study however cannot determine the hysteresis effect which is possibly caused by inhomogeneous inversion in the fluid system. A mechanistic model is developed to predict the flow characteristics as well as the pressure gradient during a phase inversion transition. It aims to predict the observed change in flow pattern from a fully dispersed flow to a dual continuous flow during phase inversion transition. The existence of the interfacial height provides a selection criterion to determine whether a momentum balance model for homogeneous flow or a two-fluid layered flow should be applied to calculate the pressure gradient. A friction factor is also applied to account for the drag reduction in a dispersed flow. This developed model shows reasonable results in predicting the switch between flow patterns (i.e. the boundaries for the phase inversion transition) and the corresponding pressure gradient. Lastly, computational fluid dynamic (CFD) simulation is applied to identify the key interphase forces in a dispersed flow. The study has also attempted to test the limitation of existing interphase force models to densely dispersed flow. From the study, it is found that the lift force and the turbulent dispersion forces are significant to the phase distribution in a dispersed flow. It also provides a possible explanation to the observed flow distribution in the experiments conducted. However, the models available in CFX are still unable to predict well in a dense dispersion (60% dispersed). This study is also suggested to form the basis for more detailed work in future to optimize the simulation models to improve the prediction of phase inversion in a CFD simulation.
Author: Nicholas P Cheremisinoff
Publisher: Gulf Professional Publishing
ISBN:
Category : Science
Languages : en
Pages : 936
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Book Description
This first volume in the series previously titled Encyclopedia of Fluid Mechanics covers multiphase systems and the transport problems associated with turbulent mixing, defining a fluid as any material displaying liquid-like behavior under the influence of deformation forces. Reports on research and application of the engineering principles associated with flow systems, highlighting topics such as jet mixing; mechanical agitation; fluidized bed reactors; and multiphase chemical reactors. Includes numerous bandw diagrams. Useful as a reference for researchers and engineers. Annotation copyright by Book News, Inc., Portland, OR
Author: Stephen Ian Clarke
Publisher:
ISBN:
Category :
Languages : en
Pages : 448
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Book Description
Author: Edward L. Paul
Publisher: John Wiley & Sons
ISBN: 0471451444
Category : Reference
Languages : en
Pages : 1450
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Book Description
Handbook of Industrial Mixing will explain the difference and uses of a variety of mixers including gear mixers, top entry mixers, side entry mixers, bottom entry mixers, on-line mixers, and submerged mixers The Handbook discusses the trade-offs among various mixers, concentrating on which might be considered for a particular process. Handbook of Industrial Mixing explains industrial mixers in a clear concise manner, and also: * Contains a CD-ROM with video clips showing different type of mixers in action and a overview of their uses. * Gives practical insights by the top professional in the field. * Details applications in key industries. * Provides the professional with information he did receive in school
Author: Sümer M. Peker
Publisher: Elsevier
ISBN: 0080553419
Category : Science
Languages : en
Pages : 535
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Book Description
This book is an undertaking of a pioneering work of uniting three vast fields of interfacial phenomena, rheology and fluid mechanics within the framework of solid-liquid two phase flow. No wonder, much finer books will be written in the future as the visionary aims of many nations in combining molecular chemistry, biology, transport and interfacial phenomena for the fundamental understanding of processes and capabilities of new materials will be achieved. Solid-liquid systems where solid particles with a wide range of physical properties, sizes ranging from nano- to macro- scale and concentrations varying from very dilute to highly concentrated, are suspended in liquids of different rheological behavior flowing in various regimes are taken up in this book. Interactions among solid particles in molecular scale are extended to aggregations in the macro scale and related to settling, flow and rheological behavior of the suspensions in a coherent, sequential manner. The classical concept of solid particles is extended to include nanoparticles, colloids, microorganisms and cellular materials. The flow of these systems is investigated under pressure, electrical, magnetic and chemical driving forces in channels ranging from macro-scale pipes to micro channels. Complementary separation and mixing processes are also taken under consideration with micro- and macro-scale counterparts.- Up-to-date including emerging technologies- Coherent, sequential approach- Wide scope: microorganisms, nanoparticles, polymer solutions, minerals, wastewater sludge, etc- All flow conditions, settling and non-settling particles, non-Newtonian flow, etc- Processes accompanying conveying in channels, such as sedimentation, separation, mixing
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 786
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Book Description
Author: John Philip Ward
Publisher:
ISBN:
Category : Fluid dynamics
Languages : en
Pages : 706
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Book Description
The momentum transfer characteristics of liquid-liquid dispersions were studied under conditions of turbulent flow in a cirular conduit. Experiments were conducted to obtain drop size, friction factors and velocity profiles for three organic phases dispersed in water. The test sections consisted of straight copper tubes 1-inch OD and 0.830-inch ID. The velocity profiles and drop size measurements were made at a point 8-1/2 feet downstream from the entrance to these tubes. The dispersions were formed and maintained by the mixing action of a high speed centrifugal pump. The organic phases were a light petroleum solvent, a light oil and a heavy oil with viscosities of 1, 15, and 200 centipoise, respectively. Flow rates were in the range 1-4 lb/sec and concentrations from 5 to 50 volume percent were studied. A photographic method of drop size determination was developed. Excellent results are obtained for drop diameters in the range 5-800 microns. Dispersions with concentrations from 1 to 50 volume percent were photographed. The drop size and the shape of the drop size distributions depended strongly on dispersed phase viscosity. The range of drop diameters was found to increase with dispersed phase viscosity. Velocity profile data were obtained in the turbulent core for three flow rates and four concentrations for the light oil dispersions and two flow rates and three concentrations for the heavy oil dispersions. The light oil dispersions were found to behave as single phase Newtonian fluids. The solvent dispersions have previously been shown to behave as single phase Newtonian liquids. The heavy oil dispersions did not behave as Newtonian fluids. These results were combined with the drop size data and a previously proposed criteria for treating dispersions as single phase fluids to give the relation [see PDF for formula] where d32 is the Sauter mean diameter of the dispersed drops. Dispersions which do not meet this criterion are presumed to have a "slip" velocity, i.e., the larger drops move relative to the fluid element in which they are contained. Thus they do not behave as a single phase fluid. The velocity profiles for the light oil dispersions were used to calculate an effective dispersion viscosity [mu subscript e]. The viscosity increased with dispersed phase concentration. Effective viscosities for the solvent dispersion had been determined by previous workers. A comparison of the viscosities and drop size data for these two systems shows that at equal concentrations the effective viscosity of a dispersion is a function of the drop size distribution, decreasing with increasing size range. Effective viscosities for the heavy oil dispersions were determined from the friction factor data and appeared to be independent of concentration in the range 5 to 17 volume percent. This may be explained by a "slip" velocity and an analysis of the drop size distributions. A study was made of one water-in-solvent dispersion and it was found that water droplets adhered to the pipe wall. The average size of these droplets could be determined from the observed friction factor data. The droplets adhering to the wall were observed to undergo coalescence with the droplets in the flowing dispersion. Several other observations made through the optical portion of the photographic arrangement tend to support the coalescence theory recently proposed by Howarth.
Author: Volfango Bertola
Publisher: Springer
ISBN: 3709125383
Category : Technology & Engineering
Languages : en
Pages : 433
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Book Description
This is an up-to-date review of recent advances in the study of two-phase flows, with focus on gas-liquid flows, liquid-liquid flows, and particle transport in turbulent flows. The book is divided into several chapters, which after introducing basic concepts lead the reader through a more complex treatment of the subjects. The reader will find an extensive review of both the older and the more recent literature, with abundance of formulas, correlations, graphs and tables. A comprehensive (though non exhaustive) list of bibliographic references is provided at the end of each chapter. The volume is especially indicated for researchers who would like to carry out experimental, theoretical or computational work on two-phase flows, as well as for professionals who wish to learn more about this topic.
