Droplet-particle collision

C. Simulation of Droplet- Particle Collision in the Leidenfrost Regime... 

An efficient numerical model to describe the unsteady, 3-D fluid flow during the droplet-particle collision with evaporation is developed (Ge and Fan, 2005). From the numerical point of view, the droplet and solid surface need to be... 

IV. System 2 Deformation Dynamics of Liquid Droplet in Collision with a Particle with Film-Boiling Evaporation... 

The coalescence rate, i.e. formation of larger droplets after collision of two droplets, depends on the number of collisions and on the properties of the adsorption layers. For dilute emulsions, as well as emulsions having V2 = 0.3—0.74, coalescence is the main process leading to the disturbance of their aggregative stability. Hence, prerequisite for the production of appreciable volumes of any type of emulsions suitable for practical application is provision of their coalescence stability. In case of o/w emulsions, maximum stability against coalescence is achieved through the formation, on the surface of the disperse phase particles, of structured adsorption layers, a structure-mechanical barrier defined by Rehbinder [8]. Such layers are... 

The mechanism by which monomer is transported between miniemulsion droplets and from these to polymer particles was the focus of a study using styrene and methyl methacrylate as comonomers [7]. The SLS/HD surGactant/cosurfactant system was used in this work. Several approaches were applied in an attempt to determine the diffusive mass-transfer coefficients of the monomeis as well as the contribution of monomer droplef polymer particle collision to the monomer transport process. Mass transfer was shown not to be a limitation in miniemulsion polymerization (i.e. equilibrium was satisfied under normal conditions). However, the thermodynamic model developed previously [6] predicted the continued existence of monomer droplets until the end of a miniemulsion polymerization provided that not all droplets were nucleated. Experimentally though, nucleation has been shown to end well before complete conversion which implies another route for monomer droplet disappearance, namely, collision. 

The contact force, Fc, arises from collision interactions between the given droplet/particle with other droplets/... 

The methods of destroying aerosols, whether liquid or sohd, are numerous. Some of the more common are illustrated in Figure 13.7. One of the most important from a practical standpoint is the use of a spray (usually water) to wash the aerosol from the gas phase. As already mentioned, for aerosols, almost every collision between aerosol particles, collisions with container walls, or collision with a water droplet will be sticky. For two aerosol particles the result is homocoagulation for the other cases the process is heterocoagulation. In each case the result will be an increase in the size of... 

Because of high turbulence in the spout and the regularity of particle mixing, different types of spouted bed are highly appropriate to the placement of spray nozzles for the purpose of particle formulation, such as granulation or coating. Two examples in which liquid spraying occurs directly at the entrance of the gas jet, and which results in a concurrent, upward flow of the droplets and gas with frequent droplet-partide collisions, are shown in Fig. 4.3. The equipment shown in Fig. 4.3a is of the conical-cylindrical type, whereas the cylindrical device of Fig. 4.3b is named Wurster equipment, after its inventor (Wurster, 1959). The main feature of... 

Decreased liquid-liquid interfacial tension (when compared with a gas-liquid system) results in higher liquid-liquid interfacial areas, which favor solid-particle droplet collisions. 

Condensation is the result of collisions between a gaseous molecule and an existing aerosol droplet when supersaturation exists. Condensation occurs at much lower values of supersaturation than nucleation. Thus, when particles already exist in sufficient quantities, condensation will be the dominant process occurring to relieve the supersaturated condition of the vapor-phase material. 

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