Foams capillary flow

Another process in connection with foam is flow of a liquid in a capillary ... 

FIGURE 6.8. In a foam system, differences in curvature along the hquid-gas interface due to distortion give rise to pressure differences and subsequent capillary flow. 

In Figure 8, the experimental results from the (4 m/day frontal advance rate, oil free) short core flood are compared to the simulated pressure drops which were based on the limiting capillary pressure principle. In this particular case was chosen at 0.35 over a range of water fractional flows from 0.01 to 0.15 to closely match the experimental data. For Sw > a fractional flow curve was chosen which matched the experimental data closely by appropriately adjusting the gas phase relative permeability curve. The water relative permeability curve remains the same as defined in the Appendix under gas/water relative permeabilities. The composite foam fractional flow curve can be seen in Figure 9. Notice the vertical section in the curve for the foam flow case lies at = 0.35. 

Lamella Number. A dimensionless parameter used to predict the likelihood that a combination of capillary suction in plateau borders and the influence of mechanical shear will cause an oil phase to become emulsified and imbibed into foam lamellae flowing in porous media (reference [19]). 

Figure 3.13 Plateau border between three cells in a foam. Due to the curvature of the liquid-gas interface, the pressure is lower by Ap at the point of intersection of the channels, leading to capillary flow...

The collapse of foam is attributed to (a) the diffusion of gas molecules from a small bubble with higher internal pressure to a large one with lower internal pressure or into the bulk gas phase surrounding the foam system, (b) coalescence of bubbles due to capillary flow that results in rupture of the lamellar film between the adjacent bubbles (usually slower than (a) and occurring even in stabilized foam system), and (c) rapid hydrodynamic drainage of liquid between bubbles that leads to rapid collapse of bubbles [35], In most nonrigid foam systems, all three mechanisms are operative simultaneously to some extent during the foam collapse process. 

When performing catalytic reactions or reactions with immobilized reactants, a bed or support has to be fiUed into a tube or capillary. The fiUing may be a bed of powder, a bed of granules or a three-dimensional material network (e.g. a polymerized foam). By special choice of the filling, e.g. very regularly sized particles, it is attempted to improve the flow characteristics. 

Accordingly, for a given capillary pressure in a porous medium there will be a specific foam flow rate at which the lamellae rupture. This is the proposed origin of the flow-rate dependence... 

Flow of trains of surfactant-laden gas bubbles through capillaries is an important ingredient of foam transport in porous media. To understand the role of surfactants in bubble flow, we present a regular perturbation expansion in large adsorption rates within the low capillary-number, singular perturbation hydrodynamic theory of Bretherton. Upon addition of soluble surfactant to the continuous liquid phase, the pressure drop across the bubble increases with the elasticity number while the deposited thin film thickness decreases slightly with the elasticity number. Both pressure drop and thin film thickness retain their 2/3 power dependence on the capillary number found by Bretherton for surfactant-free bubbles. Comparison of the proposed theory to available and new experimental... 

The experiments initially conducted were designed to test the performance of the apparatus by determination of the effect of pressure on the viseosity/quality spectrum of a typical foaming agent when it flows through a straight capillary tube. The method used is based on a technique recently developed in the laboratories(7) for this purpose, at atmospheric pressure,... 

The Viscosity-Quality Spectrum of Foam Flowing in Straight Capillary Tubes" (in press)... 

Several approaches towards monolithic GC columns based on open pore foams prepared in large diameter glass tubes were reported in the early 1970s [26,27, 110]. However, these columns had poor efficiencies, and the foams possessed only limited sample capacities in the gas-solid GC mode. Subsequent experiments with polymerized polymer layer open tubular (PLOT) columns where the capillary had completely been filled with the polymer were assumed to be failures since the resulting stationary phase did not allow the gaseous mobile phase to flow [111]. 

This composition contains abont 90 to 60 pbw of a PP block copolymer and abont 10 to 40 pbw of a PE. The block copolymer contains abont 99 to 90 wt.% of a crystalline PP and abont 1 to 10 wt.% of an amorphons ethylene/alpha-olefm copolymer and has a melt flow rate of about 2 to 15 g/10 min and a die swell ratio, measured by a capillary rheometer, of at least 1.7. Foamed materials containing a fine and uniform foam are obtained from this composition. 

A number of kinds of emulsions, foams, and suspensions may be made to flow in tubes or pipes, at scales ranging from the laboratory (e.g., capillary viscometers, Section 6.2.1) to full-scale industry (e.g., transportation pipelines, Sections 10.2 and... 

Chambers, K.T. Radke, C.J. Capillary Phenomena in Foam Flow Through Porous Media in Interfadal Phenomena in Petroleum Recovery, Morrow, N.R. (Ed.), Dekker New York, 1991, pp. 191-256. 

In dynamic regime of foam formation the size and shape of bubbles depend to a great extent on the volume rate of gas supply [8,22]. Gas consumption increases mainly on the account of increase in bubble volumes and at a certain critical volume rate, the gas begins to emerge from the capillary orifice in a continuous stream which afterwards is dispersed into individual bubbles [8,23,24]. Under this regime the influence that liquid flow turbulence exerts on bubble size is greater than that of the capillary orifice diameter and the physical properties of the liquid. 

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