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Dispersed droplets

Internal Flow. Depending on the atomizer type and operating conditions, the internal fluid flow can involve compHcated phenomena such as flow separation, boundary layer growth, cavitation, turbulence, vortex formation, and two-phase flow. The internal flow regime is often considered one of the most important stages of Hquid a tomiza tion because it determines the initial Hquid disturbances and conditions that affect the subsequent Hquid breakup and droplet dispersion. [Pg.328]

Droplet Dispersion. The primary feature of the dispersed flow regime is that the spray contains generally spherical droplets. In most practical sprays, the volume fraction of the Hquid droplets in the dispersed region is relatively small compared with the continuous gas phase. Depending on the gas-phase conditions, Hquid droplets can encounter acceleration, deceleration, coUision, coalescence, evaporation, and secondary breakup during thein evolution. Through droplet and gas-phase interaction, turbulence plays a significant role in the redistribution of droplets and spray characteristics. [Pg.330]

During the formation of a spray, its properties vary with time and location. Depending on the atomizing system and operating conditions, variations can result from droplet dispersion, acceleration, deceleration, coUision, coalescence, secondary breakup, evaporation, entrainment, oxidation, and solidification. Therefore, it may be extremely difficult to identify the dominant physical processes that control the spray dynamics and configuration. [Pg.330]

The most common types of emulsions consist of only two Hquids, water and an oil. An o/w emulsion consists of oil droplets dispersed in a continuous aqueous phase, and a w/o emulsion consists of water droplets dispersed in oil (Fig. 1). Occasionally inversion takes place an o/w emulsion changes into w/o emulsion and vice versa. More complex emulsions such as double emulsions are formed because the water droplets in a continuous oil phase themselves contain dispersed oil droplets (Fig. 2). Such oil-in-water-in-oil emulsions are noted as o/w/o. In the same manner a w/o/w emulsion may be formed, which finds use as a system for slow deHvery, extraction, etc (6,7). [Pg.196]

Gas-liquid contactors may be operated either by way of gas bubble dispersion into liquid or droplet dispersion in gas phase, while thin film reactors, i.e. packed columns and trickle beds are not suitable for solid formation due... [Pg.234]

Because flashing steam-condensate lines represent two-phase flow, with the quantity of liquid phase depending on die system conditions, these can be designed following the previously described two-phase flow methods. An alternate by Ruskin [28] uses the concept but assumes a single homogeneous phase of fine liquid droplets dispersed in the flashed vapor. Pressure drop was calculated by the Darcy equation ... [Pg.141]

Annular flow. In annular flow there is a continuous liquid in an annulus along the wall and a continuous gas/vapor phase in the core. The gas core may contain entrained droplets—dispersed mist—while the discontinuous gas phase appears as bubbles in the annulus. This flow pattern occurs at high void fractions and high flow velocities. A special case of annular flow is that where there is a gas/vapor film along the wall and a liquid core in the center. This type is called inverse annular flow and appears only in subcooled stable film boiling (see Sec. 3.4.6.3)... [Pg.152]

Hayes, D. 1993. Picoliter solder droplet dispersion. International J. Microcircuits Electron. Packaging 16 173-179. [Pg.406]

The initial momentum of the jet must also be considered, as it is significant. An effective nozzle diameter can be determined to account for this momentum since sprinkler discharges lose momentum when they strike the droplet dispersal plate. This effective diameter can be found by measuring the initial thrust (Fa) of the spray. Consequently, another group follows as... [Pg.387]

Droplet dispersion zone, in liquid atomization, 23 183-184 Droplet mean axial velocity, 23 189 variation of, 23 189... [Pg.290]

Over the past decade, instrumentation has undergone substantial developments in the areas of optics, electronics and data processing software. These have led to improvements in the reliability, accuracy and ease of use of associated instruments. Particularly, the introduction of fiber optics has allowed a greater degree of flexibility in application areas. These include, for example, measurement of oil droplet dispersion in the ocean, on-line monitoring of... [Pg.446]

Fig. 2 Optical microscopy image of a small section of a poly(ethylene oxide) (PEO) droplet dispersion sample, see text (1000-mm wide) obtained at Tc = - 2.6 °C. Amorphous droplets appear dark and semicrystalline droplets appear white under nearly crossed polarizers. The plot shows the fraction of crystallized droplets as a function of temperature upon cooling (0.4 °C min-1) for homogeneous nucleation. (Reprinted with permission from [84], Copyright 2004 by the American Physical Society)... Fig. 2 Optical microscopy image of a small section of a poly(ethylene oxide) (PEO) droplet dispersion sample, see text (1000-mm wide) obtained at Tc = - 2.6 °C. Amorphous droplets appear dark and semicrystalline droplets appear white under nearly crossed polarizers. The plot shows the fraction of crystallized droplets as a function of temperature upon cooling (0.4 °C min-1) for homogeneous nucleation. (Reprinted with permission from [84], Copyright 2004 by the American Physical Society)...
Vitale SA, Katz JL (2003) Liquid droplet dispersions formed by homogeneous liquid-liquid nucleation The Ouzo effect . Langmuir 19 4105—4110... [Pg.303]

Detonations will also propagate through liquid fuel droplet dispersions (sprays) in air and through solid-gas mixtures such as dust dispersions. Volatility of the liquid fuel plays an important role in characterizing the detonation developed. For low-volatility fuels, fracture and vaporization of the... [Pg.306]

FIG. 11. Transmission electron micrographs of freeze fractured oily droplets dispersed (a) in a hexagonal and (b) in a cubic liquid crystalline phase, bar 100 nm. From Mueller-Goymann, C., Liquid crystals in emulsions, creams and gels, containing ethoxylated sterols as surfactant, Pharm. Res. 1 154-158 (1984). [Pg.137]

A high internal phase liquid-liquid emulsion (HIPE) is one where the internal or dispersed phase droplets occupy >74% of the total volume of the emulsion. At this point the droplets contact each other and beyond this volume % the droplets are forced into distorted polyhedra. If for example styrene and divinylbenzene are employed as the continuous phase and water droplets dispersed in this oil phase using a suitable surfactant to form a HIPE, the comonomers can be polymerized to form a poly(styrene-divinylbenzene) polyHIPE. Typically the water droplets are... [Pg.13]

Inverted W/O emulsion. The premixed emulsion was composed of aqueous droplets dispersed in an oil phase containing a lipophilic surfactant. The droplet mass fraction (/>, was set to 80%. This crude emulsion was sheared into the Couette-type cell [159] at constant shear rate V = 10000 s and a... [Pg.37]


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See also in sourсe #XX -- [ Pg.331 ]




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Crystallization of droplet dispersions and polymer layers

Devices for Continuous Generation of Dispersed Droplets

Dispersed-droplet flows

Dispersion diffusion between droplets

Dispersion droplet size

Dispersion emulsion droplets

Dispersion of Melts, Liquid Droplets, and Gas Bubbles

Dispersion of droplets

Dispersion systems immiscible liquid droplets

Dispersive element droplet

Dispersive element droplet distribution

Dispersive element droplet size

Dispersive element droplet size distribution

Droplet dispersion

Droplet dispersion

Droplet formation disperse morphology

Droplet-in-Matrix (Dispersed) Phase Morphology

EPR in the form of a dispersed droplet layer

Phase dispersion droplet breakup

Phase dispersion droplet distribution

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