Dispersion fluid viscosity

Emulsions. Because emulsions are different from dispersions, different viscosity—concentration relationships must be used (71,87). In an emulsion the droplets are not rigid, and viscosity can vary over a wide range. Several equations have been proposed to account for this. An extension of the Einstein equation includes a factor that allows for the effect of variations in fluid circulation within the droplets and subsequent distortion of flow patterns (98,99). 

Determination of Controlling Rate Factor The most important physical variables determining the controlhng dispersion factor are particle size and structure, flow rate, fluid- and solid-phase diffu-sivities, partition ratio, and fluid viscosity. When multiple resistances and axial dispersion can potentially affect the rate, the spreading of a concentration wave in a fixed bed can be represented approximately... 

Although it is entirely possible for erosion-corrosion to occur in the absence of entrained particulate, it is common to find erosion-corrosion accelerated by a dilute dispersion of fine particulate matter (sand, silt, gas bubbles) entrained in the fluid. The character of the particulate, and even the fluid itself, substantially influences the effect. Eight major characteristics are influential particle shape, particle size, particle density, particle hardness, particle size distribution, angle of impact, impact velocity, and fluid viscosity. 

Functionalized copolymers from dienes and p-alkylstyrenes can serve as dispersants and viscosity index improvers. The functionalities are introduced via the aromatic units [233,234]. The polymers are selectively hydrogenated to produce polymers that have highly controlled amounts of unsaturation, permitting a highly selective functionalization. The dispersant substances may also include a carrier fluid to provide concentrates of the dispersant. 

These humic acids are not dissolved because the pH of this slurry is in the range of 4 to 9. Small amounts of fulvic acids are formed, and these are soluble in the water of the slurry. The coal-derived humic acids find applications as drilling fluid dispersants and viscosity control agents, whereas the coal-derived fulvic acids may be used to produce plasticizers and petrochemicals. 

Authors efforts in this part of the work have been concentrated on developing turbulence closures for the statistical description of two-phase turbulent flows. The primary emphasis is on development of models which are more rigorous, but can be more easily employed. The main subjects of the modeling are the Reynolds stresses (in both phases), the cross-correlation between the velocities of the two phases, and the turbulent fluxes of the void fraction. Transport of an incompressible fluid (the carrier gas) laden with monosize particles (the dispersed phase) is considered. The Stokes drag relation is used for phase interactions and there is no mass transfer between the two phases. The particle-particle interactions are neglected the dispersed phase viscosity and pressure do not appear in the particle momentum equation. 

A further problem in plotting the data is that the fluid viscosity has very little effect on the dispersion (El). Therefore, the Reynolds number might not be appropriate as a plotting variable (C5). However, no other dimensionless group has yet been proposed, and so the Reynolds number was retained in Fig. 8. 

A model has been developed to describe the penetration of polydimethylsi-loxane (PDMS) into silica agglomerates [120]. The kinetics of this process depend on agglomerate size and porosity, together with fluid viscosity. Shearing experiments demonstrated that rupture and erosion break-up mechanisms occurred, and that agglomerates which were penetrated by polymer were less readily dispersed than dry clusters. This was attributed to the formation of a network between sihca aggregates and penetrated PDMS, which could deform prior to rupture, thereby inhibiting dispersion. 

Fluid-dynamic operating conditions, such as axial or angular velocity (i.e., shear stress that determines drag force value) and transmembrane pressure (that determines disperse-phase flux, for a given disperse-phase viscosity and membrane... 

Viscosity of fluid Viscosity of plastic material Index of refraction Kinematic viscosity Dispersion factor Lacey s silt factor Ratio of pressures 3.14159... 

An article by Karam (1) gives typical data to illustrate the difference between shear rate and shear stress. Table II is extracted from cross plots of their data, showing the shear rate required with different continuous phase viscosities and one dispersed phase viscosity to break up a second fluid of the same size droplet. This shows that the shear stress in grams per centimeter squared is the basic parameter and the viscosity and shear rate are inversely proportional to give the required shear stress. 

Laun, H. M. Bung, R., and Schmidt, F. 1991. Rheology of extremely shear thickening polymer dispersions passively viscosity switching fluids. / Rheol. 35 999-1034. 

With powders, stable slurries can often be formed by using suitable dispersing fluids. These fluids should be able to wet the powder and form stable suspensions, both of which depend on their physical properties (viscosity, density and surface tension). For example, the surface tension, which is largely also a function of the pH, is known to influence the surface charge of suspended particles and therewith the stability of the slurry (for Zr02 powders see e.g. Ref. [117]). The stability of... 

Bicerano et al. (1999) provide a simplified scaling viscosity model for particle dispersions that states the importance of the shear conditions, the viscosity profile of the dispersing fluid, the particle volume fraction and the morphology of the filler in terms of its aspect ratio, the length of the longest axis and the minimum radius of curvature induced by flexibility. 

Shear viscosity of pure dispersing fluid under the specified flow conditions. 

Mixer in tank drop diameter 4 to 5000 pm capacity >0.05 L/s for viscosities <10 mPa-s. Colloid mill drop diameter 1 to 8 pm capacity 0.01 to 3 L/s for viscosities <10 mPa s but usually >1000 mPa-s. Homogenizer drop diameter 0.1 to 2 pm capacity 0.03 to 30 L/s for viscosities <10 mPa s but usually <200 mPa-s decrease the drop diameter by increasing the exit pressure. High shear disperser for viscosities 10 to 5 x 10 mPa s. Roller mills for viscosities >10 mPa-s. Motionless mixer drop diameter 100 to 1000 pm (about 0.15 times drop diameter for fluid velocity in a pipe... 

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