Atomizers spinning disk

Rotary Atomization Spinning Disk 10-200 Spray drying. Aerial distribution of pesticides. Chemical processing Good mono-dispersity of droplets. Independent control of atomization quality and liquid flow rate Satellite droplets, 360° spray pattern... 

In an evaluation of various techniques for droplet generation,1[88] periodic vibration of liquid jet, spinning disk and ultrasonic atomization techniques have been rated as the most appropriate methods for producing monodisperse sprays. These techniques were found to be very effective and appeared promising for refinement,... 

Some design concepts for generating uniform droplets have been proposed by Lee et al.[88] These include (a) centrifugal type chamber, (b) atomization by two opposing air-liquid jets, and (c) spinning disk coupled with an ultrasonic field. Some other conceptions include (d) rocket nozzle chamber, (e) frozen particles, (f) rotating brush, and (g) periodic vibrations using saw-tooth waves, etc. 

There are a number of techniques for generating aerosols, and these are discussed in detail in the LBL report (1979) and in volumes edited by Willeke (1980) and Liu et al. (1984). We briefly review here the major methods currently in use these include atomizers and nebulizers, vibrating orifices, spinning disks, the electrical mobility analyzer discussed earlier, dry powder dispersion, tube furnaces, and condensation of vapors from the gas phase. 

Hall and Diederichsen (22) projected a stream of droplets (diameters 150 to 170 microns) from the periphery of a spinning disk up into a vertical furnace maintained at a sufficiently high temperature for ignition, 710° C. The spinning disk atomizer employed was capable of producing droplets of uniform, predetermined size. Drum photographic records were obtained of the luminous portion of the droplet trajectory and drop burning times were estimated therefrom. 

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. 

Application. Cellulose acetate butyrate lacquers are usually applied by spraying (air atomization, airless, spinning disk). Application by brush or dip is possible but less commonly used. 

The centrifugal atomizer is sometimes called a rotary wheel or disk atomizer. This is a spinning disk assembly with radial or curved vanes, which rotate at high velocities (7,000-50,000 rpm) with wheel diameters of 5-50 cm. The feed is delivered near the center, spreads between the two plates, and is accelerated to high linear velocities before it is thrown off the disk in the form of thin sheets, ligaments, or elongated ellipsoids. However, the subdivided liquid immediately attains a spherical shape under the influence of surface tension. 

FIGURE 6.3 Mechanisms of drop formation by spinning disk atomization, (a) Direct formation, (b) ligament formation, and (c) sheet formation. (Reproduced from Teunou, E. and Poncelet, D., J. Food Eng, 71(4), 345, 2005. With permission.)... 

In spinning disk atomization, the factors governing the size of the droplets are the acceleration, a, or centrifngal forces, which tend to detach the drop, and the surfece tension o, which holds the drop in position. The acceleration is the result of the angular velocity of the disk (co) and the radins (Eqnation 6.16). 

In the literature, different correlations have been reported for the mean size of droplets produced by spinning disk atomization. These correlations are summarized in Table 6.3. 

List of Previously Published Correlations Reported for the Mean Droplet Size Produced by Spinning Disk Atomization... 

In spinning disk atomization, the construction of a rotating disk atonuzer depends on the application and the liquid that will be used. However, the rotating disk atomizer will always require a pump or other device for feeding liquid onto a rotating disk from which the drops will be discharged. 

M. Ahmed and M. S. Youssef. Characteristics of mean droplet size prodnced by spinning disk atomizers. Journal of Fluids Engineering, 134(7) 071103-071103, 2012. 

D. J. Ryley. Analysis of a polydisperse aqueous spray from a high-speed spinning disk atomizer. British Journal of Applied Physics, 10(4) 180, April 1959. 

Y. Senuma. Generation of monodispersed polymer microspheres by spinning disk atomization. PhD thesis, EPFL, Lausanne, 1999. 

Y. Senuma, S. Franceschin, J. Hilbom, P. Tissieres, I. Bisson, and P. Frey. Bioresorbable micro-spheres by spinning disk atomization as injectable cell carrier From preparation to in vitro evaluation. Biomaterials, 21(11) 1135-1144, 2000. 

Y. Senuma and J. G. Hilborn. High speed imaging of drop formation from low viscosity liquids and polymer melts in spinning disk atomization. Polymer Engineering and Science, 42(5) 969-982, 2002. 

Y. Senuma, C. Lowe, Y. Zweifel, J. G. Hilbom, and I. Marison. Alginate hydrogel micro-spheres and microcapsules prepared by spinning disk atomization. Biotechnology and Bioengineering, 67(5) 616-622, 2000. 

FIGURE 9.3 Different droplet production processes by dripping and jet break-up techniques, (a) Simple dripping, (b) electrostatic extrusion, (c) coaxial flow, (d) vibrating nozzle, (e) jet cutting, and (f) spinning disk atomization. 

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