Group Title: 7th International Conference on Multiphase Flow - ICMF 2010 Proceedings
Title: 1.2.4 - Determination of Coalescence Processes in Single Water-in-Oil-in-Water Double Emulsion Globules
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Title: 1.2.4 - Determination of Coalescence Processes in Single Water-in-Oil-in-Water Double Emulsion Globules Particle Bubble and Drop Dynamics
Series Title: 7th International Conference on Multiphase Flow - ICMF 2010 Proceedings
Physical Description: Conference Papers
Creator: Gaitzsch, F.
Gäbler, A.
Kraume, M.
Publisher: International Conference on Multiphase Flow (ICMF)
Publication Date: June 4, 2010
Subject: double emulsion
physical stability
partial coalescence
coalescence time
Abstract: Double emulsions, in which the dispersed drops contain droplets with the same composition as the continuous phase, have obtained a wide range of applications. Pharmaceutical, cosmetic and food industries aim for long term stability of this type of emulsion to achieve e.g. systems with a controlled drug release rate by applying hydrophilic and lipophilic emulsifiers. On the opposite side branches like the petroleum industry need to separate double emulsions of crude oil and water in short time. Emulsions in extraction processes can be separated by transferring the primary emulsion into a double emulsion to achieve high separation efficiency with low residence times. The aim of this study is to understand the fundamentals of this type of phase separator working on the principle of phase inversion. Coalescence of the internal water droplets with the surrounding aqueous bulk phase, so called droplet expulsion, is one of the key mechanisms for fast separation. Therefore single drop experiments with stagnant single water-in-oil-in-water (W/O/W) double emulsion globules are performed. The influence of the internal droplet and overall drop diameter ratio and the physical properties on coalescence time and partial coalescence are investigated. The experiments are carried out with saturated ultra purified water and silicone respectively paraffin oil. A formation device for single water-in-oil-in-water double emulsion globules is developed. Two micro dosing pumps feed oil and water alternating. The water droplet is injected into the oil volume. The overall diameter of the drop containing the oil volume and the initial water droplet is varied in the range of 2.50 to 3.25 mm. The initial internal water droplet diameter is set between 0.8 and 1.75 mm. The events are recorded with a high-speed camera and backlighted by a LED. The diameters and coalescence times are determined by means of image processing software. Due to the stochastic nature of coalescence processes a multitude of events is analysed for each parameter set and model system. Depending on the physical parameters cascades of up to four partial coalescence steps are observed. The size ratio of the secondary and mother droplet is constant. A value of 0.5 is found when partial coalescence occurs. No general critical Bond and Ohnesorge numbers can be found to predict the formation of daughter droplets during coalescence for different physical properties. The results of the coalescence time, including the time from the first contact of the inner droplet with the interface to the rupture of the film, show an intense scatter. Nevertheless it can be stated, that the coalescence time increases with increasing internal water droplet diameters. No influence of the overall diameter on the coalescence time and the occurrence of partial coalescence is found in the investigated diameter range.
General Note: The International Conference on Multiphase Flow (ICMF) first was held in Tsukuba, Japan in 1991 and the second ICMF took place in Kyoto, Japan in 1995. During this conference, it was decided to establish an International Governing Board which oversees the major aspects of the conference and makes decisions about future conference locations. Due to the great importance of the field, it was furthermore decided to hold the conference every three years successively in Asia including Australia, Europe including Africa, Russia and the Near East and America. Hence, ICMF 1998 was held in Lyon, France, ICMF 2001 in New Orleans, USA, ICMF 2004 in Yokohama, Japan, and ICMF 2007 in Leipzig, Germany. ICMF-2010 is devoted to all aspects of Multiphase Flow. Researchers from all over the world gathered in order to introduce their recent advances in the field and thereby promote the exchange of new ideas, results and techniques. The conference is a key event in Multiphase Flow and supports the advancement of science in this very important field. The major research topics relevant for the conference are as follows: Bio-Fluid Dynamics; Boiling; Bubbly Flows; Cavitation; Colloidal and Suspension Dynamics; Collision, Agglomeration and Breakup; Computational Techniques for Multiphase Flows; Droplet Flows; Environmental and Geophysical Flows; Experimental Methods for Multiphase Flows; Fluidized and Circulating Fluidized Beds; Fluid Structure Interactions; Granular Media; Industrial Applications; Instabilities; Interfacial Flows; Micro and Nano-Scale Multiphase Flows; Microgravity in Two-Phase Flow; Multiphase Flows with Heat and Mass Transfer; Non-Newtonian Multiphase Flows; Particle-Laden Flows; Particle, Bubble and Drop Dynamics; Reactive Multiphase Flows
 Record Information
Bibliographic ID: UF00102023
Volume ID: VID00022
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: 124-Gaitzsch-ICMF2010.pdf

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