Many of these techniques are labor intensive, time consuming, and destructive and therefore are unsuitable for rapid quality assurance tests. This procedure is continued until all of the water has evaporated, and then its volume is determined from the calibrations on the side arm. An organic solvent is mixed with the emulsion, and the flask is heated to cause the water to evaporate and collect in the side arm. The emulsion is placed in a specially designed flask which has a calibrated side arm. The moisture content can also be determined by distillation. The simplest of these involves weighing an emulsion before and after the water has been evaporated, which may be achieved by conventional oven, vacuum oven, microwave oven, or infrared light. The water content of an emulsion can be determined using a variety of proximate analysis techniques (Mikula 1992, Pal 1994, Pomeranz and Meloan 1994, Bradley 1994). A similar procedure is involved in the detergent method, except that rather than sulfuric acid, a surfactant is added to promote droplet coalescence. The bottle is centrifuged to facilitate the separation of the oil and aqueous phases, and the percentage of oil in the emulsion is determined from the calibrated neck of the bottle. In the Gerber and Babcock methods, an emulsion is placed in a specially designed bottle and then mixed with sulfuric acid, which digests the interfacial membrane surrounding the droplets and thus causes coalescence (Min 1994). This problem has been overcome in a number of nonsolvent techniques developed to measure the fat content of dairy emulsions. A possible difficulty associated with applying this technique to oil-in-water emulsions is that the interfacial membrane may be resistant to rupture, and therefore all of the oil is not released. The solvent is then physically separated from the aqueous phase, and the oil content is determined by evaporating the solvent and weighing the residual oil. The sample to be analyzed is mixed with a nonpolar organic solvent which extracts the oil. A variety of solvent-extraction techniques are available for measuring fat content (Min 1994, Pal 1994). Moreover, for a given water fraction, the reduction in drag of stable water-in-oil emulsions was found to be more pronounced in smaller pipe diameter due to the shear thinning effect and became significant at higher values of water fraction and Re.The concentration of droplets in an emulsion can be determined using many of the standard analytical methods developed to determine the composition of foods (Nielsen 1994, Pomeranz and Meloan 1994). In one case, a decrease of water volume fraction from 0.7 to 0.6 resulted in a 60 to 75% drag reduction, depending on the Reynolds number (Re). Furthermore, a significant reduction in emulsion viscosity and pressure drop with decreasing water fraction was observed. In addition, as water fraction increased emulsion stability increased. The results demonstrated a shear thinning behavior for the emulsions being investigated. Emulsion physical properties such as stability, type, and rheology measurements were correlated to pressure drop measurements in a flow loop consisting of 1-in and 0.5-in horizontal pipe diameters at constant (ambient) emulsion temperature. This study experimentally investigates the role of dispersed phase (water) fraction on frictional drag in different pipe diameters.įlow loop experiments were conducted to study the effect of water fraction on the flow characteristics of surfactant-stabilized water-in-oil emulsions. High friction losses while pumping emulsified acid in a carbonate stimulation treatment limit the injection rate, which can negatively impact operational efficiency consequently, reducing friction is highly desirable.
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