Coalescence process

A stable cloud of water ia fuel usually means that a surfactant is present to form a stable water-ia-oil emulsion. Smaller droplets resist natural coalescence processes. A surfactant that is potent as an emulsifying agent is apt to disarm the coalescing filters, aHowiag excess water to be deUvered with fuel. 

The first flow pattern zone corresponds to the isolated bubble (IB) regime where the bubble generation rate is much higher than the coalescence rate. It includes both bubbly flow and/or slug flows and is present up to the onset of coalescence process domination. The second zone is the coalescing bubble (CB) regime, which is... 

Steam-liquid flow. Two-phase flow maps and heat transfer prediction methods which exist for vaporization in macro-channels and are inapplicable in micro-channels. Due to the predominance of surface tension over the gravity forces, the orientation of micro-channel has a negligible influence on the flow pattern. The models of convection boiling should correlate the frequencies, length and velocities of the bubbles and the coalescence processes, which control the flow pattern transitions, with the heat flux and the mass flux. The vapor bubble size distribution must be taken into account. 

Mechanical compatibilization is accomplished by reducing the size of the dispersed phase. The latter is determined by the balance between drop breakup and coalescence process, which in turn is governed by the type and severity of the stress, interfacial tension between the two phases, and the rheological characteristics of the components [9]. The need to reduce potential energy initiates the agglomeration process, which is less severe if the interfacial tension is small. Addition... 

In summary, control of the surface chemistry and the presence of clean surfaces allow the coalescence of initially isotropic nanoparticles into regular, often monodisperse, nano-objects of anisotropic shape (cubes, rods, wires). It is possible that the inclusion of the initially present nanoparticles into superlattices play an important role in these coalescence processes. 

Several factors contribute to the dual nature of silicone defoamers. For example, soluble silicones can concentrate at the air-oil interface to stabilize bubbles, while dispersed drops of silicone can accelerate the coalescence process by rapidly spreading at the gas-liquid interface of a bubble, causing film thinning by surface transport [1163]. 

Chesters, A. K., The modeling of coalescence processes in fluid-liquid dispersions A review of current understanding. Trans. Inst. Engrs. 69, 259-270 (1991). 

Coalescence process, 10 117, 765 Coalescence rates, 11 775 Coal gas, 6 784-790 Coal gasification, 6 760-765, 771-832 12 332. See also Coal gasification processes... 

T. H. Whitesides and D.S. Ross Experimental and Theoretical Analysis of the Limited Coalescence Process Stepwise Limited Coalescence. J. Colloid Interface Sci. 169, 48 (1995). 

Other experiments performed by Bergeron [34] on air foams stabilized with ionic surfactants reveal that the so-called Gibbs or dilatational elasticity e may play an important role in the coalescence process. The Gibbs elasticity measures the variation of surface tension yi t associated to the variation of the surfactant surface concentration F ... 

It is argued that the kinetics of the limited coalescence process is determined by the uncovered surface fraction 1 - t and by the rate of thinning (drainage) of the films formed between the deformable droplets [46,47], The homogeneous and monodisperse growth generated by limited coalescence is intrinsically different from the polydisperse evolution observed for surfactant-stabilized emulsions. As noted by Whitesides and Ross [48], the mere fact that coalescence halts as a result of surface saturation does not provide an obvious explanation of the very... 

A number of rate constants for reactions of transients derived from the reduction of metal ions and metal complexes were determined by pulse radiolysis [58]. Because of the shortlived character of atoms and oligomers, the determination of their redox potential is possible only by kinetic methods using pulse radiolysis. In the couple Mj/M , the reducing properties of M as electron donor as well as oxidizing properties of as electron acceptor are deduced from the occurrence of an electron transfer reaction with a reference reactant of known potential. These reactions obviously occur in competition with the cascade of coalescence processes. The unknown potential °(M /M ) is derived by comparing the action of several reference systems of different potentials. 

Figure 13 Scheme of the influence of the dose rate on the competition between the inter-metal electron transfer and the coalescence processes during the radiolytic reduction of mixed metal ion solutions. Sudden irradiation at high dose rates favor alloying, whereas low dose rates favor coreshell segregation of the metals because of metal displacement in the clusters. 

Due to various advantagss, electrostatic coalescing process has found wide applications and ras bcc. employed in Kuwait field desalting plants,... 

The nature of the upper vesicular zone is determined not by hydrostatic pressure of the overlying flow thickness, but rather by the bubble rise and coalescence processes within the flow... 

Formation of solubilized surfactant-latex complexes can influence the properties and performance of vinyl acrylic latexes prepared with NaLS and other penetrating type anionic surfactants. Such complexes seem to affect glass transition temperature and film coalescence process (12). 

When solid particles come in contact with each other at elevated temperatures, they tend to coalesce, thereby decreasing the total surface area. This process is called sintering (18). It is usually accompanied by a decrease in the total volume of the particulate bed. A decrease in surface area brings about a decrease in (surface) free energy hence, the surface tension is the driving force for the coalescence process. 

Figure 6. Mixing in a flow reactor with two unmixed feedstreams (60). Left, Maximum age, maximum species mixedness middle, minimum age, maximum species mixedness (mixing in this case can also he assumed to occur by molecular diffusion between two tubes having the same and (T9.)) and right, mixing between particles of the same life expectancy by a random-coalescence process (77).

One of the most important factors regulating the rate of foam collapse (especially coalescence process) is the surfactant kind, along with the additives, both affecting the equilibrium film thickness, film stability, rate of film thinning and rate of drainage. Unfortunately, data about the kinetics of internal foam collapse for foams from various surfactants under comparable conditions are very poor. 

A method of parallel plate mode was used to estimate the shear stress and viscosity of a foam [35], The lower plate was fixed and the upper one was rotated. In order to exclude the slip of the foam on the walls the plate was covered with a sand paper. To diminish the drainage and coalescence processes, the foam was produced from a solution with a high concentration of the foaming agent to which dodecyl alcohol was added. Proper linear... 

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