Melt droplets

In Madejski s full model,l401 solidification of melt droplets is formulated using the solution of analogous Stefan problem. Assuming a disk shape for both liquid and solid layers, the flattening ratio is derived from the numerical results of the solidification model for large Reynolds and Weber numbers ... 

There have been books on droplet-related processes. However, the present book is probably the first one that encompasses the fundamental phenomena, principles and processes of discrete droplets of both normal liquids and melts. The author has attempted to correlate many diverse mechanisms and effects in a single and common framework in an effort to provide the reader with a new perspective of the identical basic physics and the inherent relationship between normal liquid and melt droplet processes. Another distinct and unique feature of this book is the comprehensive review of the empirical correlations, analytical and numerical models and computer simulations of droplet processes. These not only provide practical and handy approaches for engineering calculations, analyses and designs, but also form a useful basis for future in-depth research. Therefore, the present book covers the fundamental aspects of engineering applications and scientific research in the area. 

Apparently, the direct transition from vapor to solid is less common than the double transition vapor — liquid — solid, see, e.g., Refs.158-160). From the rate of solidification of metal droplets (average diameter near 0.005 cm) at temperatures 60° to 370° below their normal melting points, the 7sl was concluded158) to be, for instance, 24 for mercury, 54 for tin, and 177 erg/cm2 for copper. For this calculation it was necessary to assume that each crystal nucleus was a perfect sphere embedded in the melt droplet the improbability of this model was emphasized above. 

Evidence for the liquid-drop character of B-swirl defects in Si comes from the observation that upon melting, droplets of liquid Si are formed in the interior of the solid phase (22). 

A schematic diagram of a prill tower is given in Fig. 7.7. Some details of an installation for fertilizer materials are listed in Table 1.2. Melt is provided to the prilling devices at the top of the tower from reactor/evaporator systems in the case of a fertilizer material such as ammonium nitrate or from a melt tank in the case of fusible materials such as petroleum wax and coal tar pitch. Melt droplets travel counter-current to cooling air and the solid prills are conveyed away from the bottom of the tower to appropriate downstream treatments such as cooling, clay treatment and storage. 

The measurements were performed on a sample consisting of polystyrene (PS) and polymethylmethacrylate (PMMA). After depositing a melt droplet of each polymer on the freshly cleaved surface of an NaCl single crystal and... 

Chondrites—meteorites from parent bodies in the asteroid belt that never melted—represent the most primitive samples available of material that formed in the protoplanetary nebula. Chondrites are mainly composed of chondrules, with smaller amounts of refractory inclusions and a fine grained matrix of silicate, metal, and sulfide. Chondrules are roughly spherical objects, typically —1 mm in size, and largely composed of olivine and pyroxene (Taylor, 2001). They appear to have formed from melt droplets that cooled on timescales of... 

As shown in Figure 2, according to the main reaction zones, the converter is divided into three sections. These are treated assuming complete (local) equilibrium the hot spot, where the reaction between oxygen and iron melt takes place, the metal-slag zone, where the conversion of the FeO from the hot spot with melt droplets takes place, and the metal bath. The fourth zone, the slag, as shown in Figure 2, is needed for the temporal discretisation of the model. It is assumed that... 

Formation of bead-like particles typical in solidification of melt droplets see also Prilling). 

The formation of spherical particles by solidification of melt droplets. 

The original building blocks of the Earth are thought to be preserved in a group of primitive meteorites known as the carbonaceous chondrites. These contain inclusions rich in calcium-aluminum minerals which formed at high temperature within 104-105 years of the formation of the solar system. Also present are chondrules, olivine-rich spheroidal melt droplets, a few millimeters in diameter, which formed within the first 4 Ma of Solar System history. 

Chondrules - spheroidal ultramafic melt droplets a millimeter or so in diameter, which tend to dominate the texture of their host and from which chondrites take their name. 

Beading [n.] Formation of bead-like particles typical in solidification of melt droplets. (See also prilling, pastillation, melt solidification.)... 

The formation of spherical particles by solidification of melt droplets. (See also melt solidification, shot forming.) A paddle type mixer usually with open top, single or double shafts, and trough shaped chamber. 

For a variety of applications, spherical particles are required. Many of these are associated with the field of powder metallurgy (Chapter 7). While it is relatively easy to produce spherical particles from low-melting materials by conventional techniques, in which melt droplets are produced and solidified in spray (prilling) towers [B.97], refractory solids in general and, specifically, high-melting metals can not be converted by this simple technique. However, if the solid is available in powder form (Section 13.3, refs. 82, 85, 89, 90, 94), various methods are available to produce spherical particles by agglomeration. 

Caution. Finely crystalline Li3N is deposited at all inner parts of the equipment which have been cooler than the furnace. When the vessel is opened, the deposited Li3N can ignite. Burning melt droplets can be formed which drop from the walls of the vessel or seed holder. The finely divided Li3N also ignites on contact with H20. 

The crystaUization behavior of a dispersed melt-phase, for example discrete melt droplets, in an amorphous matrix can be dramatically affected... 

The first investigations concerning the crystallization in discrete droplets date from 1880 Van Riemsdyk reported that small gold melt droplets... 

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