Continuous phase liquid

The use of the nomograph is as follows Find the intersecting point of the curves of continuous phase and dispersed phase viscosities on the binary field (left side of nomograph). A line is drawn from this point to the common scale volume fraction of dispersed phase and continuous phase liquids. The intersection of this line with the Viscosity of Emulsion scale gives the result. 

Example. The viscosity of the continuous phase liquid is 20. The viscosity of the dispersed phase liquid is 30. The volume fraction of the dispersed phase liquid is 0.3. The nomograph shows the emulsion viscosity to be 36.2. 

When two immiscible liquids are stirred together, one phase becomes dispersed as tiny droplets in the second liquid which forms a continuous phase. Liquid-liquid extraction, a process using successive mixing and settling stages (Volume 2, Chapter 13) is one important example of this type of mixing. The liquids are brought into contact with... 

Chemically, the preparation of a "stable" foam or emulsion requires the use of a surfactant to aid in dispersion of the internal phase and prevent the collapse of the foam (or emulsion) into separate bulk phases. The selection of a surfactant is made on the basis of severity of conditions to be encountered, the gas to be entrained (N2, C02, LPG, CH, or air), the continuous phase liquid (water, alcohol, or oil), and half-life of foam stability desired. 

The objective of this paper is to illustrate the efficacy of inferring the interdroplet forces in a concentrated protein stabilized oil-in-water emulsion from the knowledge of the equilibrium profile of continuous phase liquid holdup (or, dispersed phase faction) when the emulsion is subjected to a centrifugal force field. This is accomplished by demonstrating the sensitivity of continuous phase liquid holdup profile for concentrated oil-in-water emulsions of different interdroplet forces. A Mef discussion of the structure of concentrated oil-in-water emulsion is presented in the next section. A model for centrifugal stability of concentrated emulsion is presented in the subsequent section. This is followed by the simulation of continuous phase liquid holdup profiles for concentrated oil-in-water emulsions for different centrifugal accelerations, protein concentrations, droplet sizes, pH, ionic strengths and the nature of protein-solvent interactions. 

For a dodecahedral arrangement, the continuous phase liquid holdup e is given by... 

From the above equation, the variation of equilibrium disjoining pressure and the radius of curvature of plateau border with position for a concentrated emulsion can be obtained. If the polarizabilities of the oil, water and the adsorbed protein layer (the effective Hamaker constants), the net charge of protein molecule, ionic strength, protein-solvent interaction and the thickness of the adsorbed protein layer are known, the disjoining pressure II(x/7) can be related to the film thickness using equations 9 -20. The variation of equilitnium film thickness with position in the emulsion can then be calculated. From the knowledge of r and Xp, the variation of cross sectional area of plateau border Qp and the continuous phase liquid holdup e with position can then be calculated using equations 7 and 21 respectively. The results of such calculations for different parameters are presented in the next session. 

Alternatively, experimental measurement of the variation of equilibrium continuous liquid holdup with position for a concentrated oil-in-water emulsion can be employed to infer the variation of disjoining pressure with film thickness. Since the continuous phase liquid holdup e is known as a function of position, xp, Op and r can be calculated using equations 7,21 and 24. Equation 24 will then yield the disjoining pressure II at the film thickness xp. ... 

Simulation of Equilibrium Profiles of Film Thickness and Continuous Phase Liquid Holdup... 

FIGURE 2. Continuous phase liquid holdup profiles (CPLHP) for different centrifugal accelerations for droplet size R = 5jc10 /w, surface concentration r=5jcl0 il g//n, ionic strength m =0.1M,thickness of adsorbed protein layer L, = 12xl(T /n and zeta potential = 12mV. 

FIGURE 7. Continuous phase liquid holdup profiles (CPLHP) for different zeta potentials for droplet size / =50bcl0" /n, centrifugal acceleration Qc = 10 m lsec, ionic strength m=0.1Af, thickness of adsorbed protein layer Lg = 12xl(T m and surface concentration r = 5jc IQT kglnr. 

Continuous-phase liquid holdup, 235 Conventionsd production of soy sauce final product, 203 koji production, 200-201 moromi production, 201-203 process, 200,201/... 

This work shows that high shear rates are required before viscous effects make a significant contribution to the shear stress at low rates of shear the effects are minimal. However, Princen claims that, experimentally, this does not apply. Shear stress was observed to increase at moderate rates of shear [64]. This difference was attributed to the use of the dubious model of all continuous phase liquid being present in the thin films between the cells, with Plateau borders of no, or negligible, liquid content [65]. The opposite is more realistic i.e. most of the liquid continuous phase is confined to the Plateau borders. Princen used this model to determine the viscous contribution to the overall foam or emulsion viscosity, for extensional strain up to the elastic limit. The results indicate that significant contributions to the effective viscosity were observed at moderate strain, and that the foam viscosity could be several orders of magnitude higher than the continuous phase viscosity. 

The mass transfer coefficient kL of oxygen transfer in fermenters is a function of Sauter mean diameter D32, diffusivity DAB, and density p, viscosity pc of continuous phase (liquid phase). Sauter-mean diameter D32 can be calculated from measured drop-size distribution from the following relationship,... 

As the liquid holdup increases, the effective orifice diameter may become so small that the liquid surface becomes continuous across the cross section of the column. Column instability occurs concomitantly with a rising continuous-phase liquid body in the column. Pressure drop shoots up with only a slight change in gas rate (condition C or C ). The phenomenon is called flooding and is analogous to entrainment flooding in a tray column. 

Keep in mind that the viscosity of the suspension and of the continuous phase liquid depend on the shear rate (shear stress) in most cases. 

In a centrifuge, as in a gravity thickening device, the diameter of the particle, the difference in density between the particle and the continuous-phase liquid, as well as the viscosity of the liquid, are important process parameters. 

Figure 9.38 shows two liquid drops approaching one another. The net force due to the change in momentum caused by the collision is F. Drops are separated from each other by a him of continuous-phase liquid of thickness h. 

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