Emulsions, bubble

During the process of three phase foam thinning, three distinct films may occur foam films (water film between air bubbles), emulsion films (water between oil droplets) and pseudoemulsion films (water film between air and oil droplets) (Figure 1). To study the behavior of these films and particularly the oil droplet-droplet, oil droplet-air bubble and oil droplet-foam frame interactions it is necessary to utilize numerous microscopic techniques, including transmitted light, microinterferometric, differential interferometric and cinemicrographic microscopy. 

An estimate of the time available for growth, Tp, may be obtained from the dense-phase tangential velocity Uijj (equal to r, dijjfdd, with ijj the angle measured from the vertical) at the bubble-emulsion interface ... 

Tangential velocity along the bubble-emulsion interface Time-averaged interstitial velocity of liquid Interstitial mean liquid velocity, Eq. (4-15) Ascending velocity of bubbles... 

The value of k b (the overall coefficient at the bubble-emulsion interface) can be calculated by an elaborate method described by Miyauchi and Marooka (1969) (see also Doraiswamy and Sharma, 1984), giving a value of 0.819 cm/s. Thus,... 

Ramsden W (1903) Separation of solids in the surface-layers of solutions and suspensions (observations on surface-membranes, bubbles, emulsions, and mechanical coagulation). Preliminary account. Proc R Soc Lond A Math Phys Eng Sci 72 156-164... 

Partially because of the backmixing behavior and partially because of the elEciency of contact between fluid- and catalyst-phases, fluidized beds are less efficient than fixed beds, at least in terms of the amount of catalyst required to attain a given conversion. Although plug flow seems reasonable for the motion of the bubbles, particularly in the Geldhart A-A regions, bubble-emulsion interchange. 

An important feature of fluidized-bed reactors is mass transfer between bubble and emulsion. Several models have been proposed for this exchange. The Davidson model assumes no cloud, so that only one mass transfer coefficient be (for direct bubble-emulsion exchange) is involved. On the other hand, the... 

Abstract. The stability of suspensions/emulsions is under consideration. Traditionally consideration of colloidal systems is based on inclusion only Van-der-Waals (or dispersion) and electrostatic components, which is refereed to as DLVO (Derjaguin-Landau-Verwey-Overbeek) theory. It is shown that not only DLVO components but also other types of the inter-particle forces may play an important role in the stability and colloidal systems. Those contributions are due to hydrodynamic interactions, hydration and hydrophobic forces, steric and depletion forced, oscillatory structural forces. The hydrodynamic and colloidal interactions between drops and bubbles emulsions and foams are even more complex (as compared to that of suspensions of solid particles) due to the fluidity and deformability of those colloidal objects. The latter two features and thin film formation between the colliding particles have a great impact on the hydrodynamic interactions, the magnitude of the disjoining pressure and on the dynamic and thermodynamic stability of such colloidal systems. 

If the mesoscale structure is assumed to take the form of bubbles, then, for a bubble-emulsion structure, the mass balance equation of gas keeps the same as Eq. (22). If the bubble is assumed to be void of solids, as is the case in Shi et al (2011), then the mass balance equation of solids, Eq. (23), can be further simplified by using pf = 0, that is. 

Kunii and Levenspiel (1969, 1991) considered the vaporization or sublimation of A from all particles in the bed. They assumed that fresh gas enters the bed only as bubbles, and that at steady state the measure of sublimation of A is given by the increase in Ca with height in the bubble phase. They further assumed that the equilibrium is rapidly established between Ca at the gas-particle interphase and its surroundings. The above assumptions lead to a mass transfer equation in terms of a bubble-emulsion mass transfer coefficient, GB-... 

A manifestation of surface forces (either between particles, bubbles, emulsion droplets or in the vicinity of the three-phase contact line (Pig. 1)) is the disjoining pressure. Let us consider the interaction of two thick plain parallel surfaces divided by a thin layer of liquid of thickness h (aqueous electrolyte solution, for example) in Fig. 2. The surfaces are not necessarily the same, as shown by two examples (i) 1 is air, 3 is a liquid film, 2 is solid support (ii) 1 and 2 are air or a liquid, 3 is a liquid film (of a different liquid). Example (i) is as a liquid film on a solid support and models a liquid layer in the vicinity of the... 

Bubble diameter just above the distributor Maximum bubble diameter Bubble diameter Mass transfer coefficient (bubble emulsion phase)... 

We distinguish different types of liquid films. Foam films are liquid lamellae between two gas phases. They form, for example, between two bubbles. Emulsion films are films of liquid A between two immiscible liquids B. This can, for example, be a water film between two oil drops. When a solid surface is involved, we have a liquid film on top of a solid substrate. Such films form, for example, when a particle collides with a bubble. 

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