Atomization of liquids

For high liquid flow rates, ReLf > 300, and at all gas rates, roll waves appear on the film, accompanied by an atomization of liquid from the wave crests. 

Atomization" of liquids and solids Rate of "atomization" of mercury and glass in water accelerated... 

Whistle Atomization 50 (10kHz, <75 l/min) 7 (>20 kHz, 0.125kg/min 0.33 MPa) Atomization of liquid metals for powder production Fine droplets, High gas efficiency Broad droplet size distribution... 

In addition to water atomization, oil atomization using various hydrocarbons (oils) is the only other liquid atomization process used in the atomization of liquid metals. Due to the similarity of these two atomization processes, water atomizers can be readily adapted to oil atomization. Some problems inherent in water atomization, such as powder oxidation, can be avoided in oil atomization. The cost-effectiveness is superior to gas atomization, but not as good as water atomization. 

Figure 3.9. Regimes in rotary (centrifugal) atomization of liquids (a) Direct Droplet Formation, (b) Direct Droplet and Ligament Formation, (c) Ligament Formation, and (d) Film or Sheet Formation.

Most commercial and near-commercial atomization processes for liquid metals/alloys involve two-fluid atomization or centrifugal atomization. As suggested by many experimental observations, two-fluid atomization of liquid metals is typically a three-stage process, 3IX 3 yl whereas centrifugal atomization may occur in three different regimes.[5][320] Many atomization modes and mechanisms for normal liquids may be adopted or directly employed to account... 

Droplet Formation in Gas Atomization. Experimental and modeling studiesl160 161 169] 318] 319] 321]- 325] have shown that gas atomization of liquid metals in spray forming and powder metallurgy processes may take place in two primary modes, i.e., liquid jet-ligament breakup and liquid film-sheet breakup. 

While gas atomization of liquid metals is generally viewed as a three-step process, the Kohlswa ultrasonic gas atomization is suggested to be a single-step process.[172] When particles of an atomization gas at extremely high velocities strike a liquid metal... 

Droplet Formation in Centrifugal Atomization. The mechanisms of centrifugal atomization of liquid metals are quite similar to those for normal liquids. Three atomization modes have been identified in rotating electrode atomization process, i.e., (I) Direct Droplet Formation, (2) Ligament Disintegration, and (3) Film/Sheet Disintegration.1[189][32°] are aiso applicable to the centrifugal atomiza-... 

The liquid properties of primary importance are density, viscosity and surface tension. Unfortunately, there is no incontrovertible evidence for the effects of liquid viscosity and surface tension on droplet sizes, and in some cases the effects are conflicting. Gas density is generally considered to be the only thermophysical property of importance for the atomization of liquids in a gaseous medium. Gas density shows different influences in different atomization processes. For example, in a fan spray, or a swirl jet atomization process, an increase in the gas density can generally improve... 

Detailed descriptions of the practical aspects of atomizer performance, plant design, and operation for powder productionthrough atomization of liquid metals have been given by Yule and Dunkley... 

On the basis of the experimental observations,l160 169 327 Liu[325] conceived a liquid film-sheet breakup model for atomization of liquid metals with close-coupled atomizers. In this atomization model, it was postulated that atomization of a liquid metal with a close-coupled atomizer may occur in the following sequence (1) formation of a liquid film, (2) conversion of the liquid film into a liquid sheet, (3) primary breakup of the liquid sheet into droplets, (4) droplet... 

Methods of near-field, midfield and ensemble (global) imaging and real-time visualization have been developed for monitoring gas atomization of liquid metals.[327] The primary process sensors and monitors used include high-speed video and infrared imaging systems. The process monitors allowed continuous and detailed observations of the atomization process and enabled measurements of the key parameters necessary for adequate control and optimization of the process. The sensors provided the operators with real-time information on the temperature of nozzle tip, visual characteristics of atomization plume, and gas and metal flow rates. The images can be displayed in real time, offering the potential for more responsive process control. 

Headley, A. D. and Jackson, N. M., The effect of the anion on the chemical shifts of the aromatic hydrogen atoms of liquid l-butyl-3-methylimidazolium salts, /. Phys. Org. Chem., 15, 52, 2002. 

Walzel P. Spraying and Atomizing of Liquids, in Ullmann s Encyclopedia of Industrial Chemistry. Vol. B2. Chapter 6. VCH Weinheim/Germany, 1988. 

Dahl HD, Muschelknautz E. Atomization of liquids and suspensions with hollow cone nozzles. Chem Eng Technol 1992 15 224-231. 

Before the derivation of a general expression for the partial molal quantities, a simple example of partial molal quantity is treated. Consider liquids metal A and metal B, which form a complete solution of composition A Bj Let the volume of 1 g atom of liquid A and liquid B be and Pg, respectively. The volume of the solution, F(x), the mole fraction of which is x (1 — x), generally satisfies the following relation. 

Nozzle port size is selected to accomodate spray liquid viscosity and delivery rate and may influence droplet size because it affects the velocity of liquid at a given spray rate. At low atomizing air pressures and volumes, a low liquid velocity allows more complete atomization of liquid. Using a smaller nozzle port at the same spray rate generally results in a larger mean droplet size due to the higher liquid delivery velocity. At high atomization air pressures and volumes, this effect is minimized. 

The Atomization of Liquid Fuels, Wiley, NY(1953) 4)P.Barret, Etude de Mecanisme... 

Therefore, atomization of liquids and control of droplet formation by means of ultrasonics has potentially important applications for propulsion systems and the dispersal of chemical agents, as well as for the creation of mists and fogs... 

Spinning Disk Atomization. The spinning disk produces a continuous spray which spreads radially outwards from the periphery of the disk. A major difference of this technique in comparison with pressure atomization of liquids is mentioned by Marshall and Seltzer (5F), who give a detailed theory of atomization for both smooth and vaned disks. High velocities are achieved without a pressure increase. 

Giffen and Muraszew (7C) have published a very complete text on the atomization of liquid fuels, which includes an excellent bibliography. Among other topics they discuss the mechanism of jet breakup, atomizer and spray characteristics, effect of physical properties on the spray, and experimental techniques. 

C) Giffen, E., Muraszew, A., Atomization of Liquid Fuels, Chapman and Hall, London, 1953. 

I he experimental determination of drop-size distributions of fuel sprays is important for all studies involving the atomization of liquid fuels. Investigations of the mechanism of atomization, influences of the many factors that determine fineness of the spray, and methods of atomization and nozzle design all require some means for determining the extent to which the liquid is broken up into droplets in preparation for combustion. 

In contrast to the large variety of averages and measures of dispersion prevalent in the literature, the number of basic distributions which have proved useful is relatively small. In droplet statistics, the best known distributions include the normal, log-normal, Rosin-Rammler, and Nukiyama-Tanasawa distributions. The normal distribution often gives a satisfactory representation where the droplets are produced by condensation, precipitation, or by chemical processes. The log-normal and Nukiyama-Tanasawa distributions often yield adequate descriptions of the drop-size distributions of sprays produced by atomization of liquids in air. The Rosin-Rammler distribution has been successfully applied to size distribution resulting from grinding, and may sometimes be fitted to data that are too skewed to be fitted with a log-normal distribution. 

Ibid., Preliminary Investigation of the Atomization of Liquids Injected into an Air... 

Giffen, E, and A, Muraszew The Atomization of Liquid Fuels, John Wiley Sons Inc., New York, NY, 1953. 

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