Porous solids permeability

Both ends of a number of parallel membrane tubes or porous solid tubes lined with permeable membranes are connected Lo common header rooms. One ofthe two headers serves as the entrance of the feed, while the other header serves as the outlet for the retentate. The permeate is collected in the shell enclosing the tube bundle. 

Another approach to radiation loss reduction might be the alteration of the salt water surface in some manner to lower its emissivity for thermal radiation. If a transparent thin liquid film or porous solid film of low thermal emissivity, permeable to water vapor, could be floated on the salt water, solar energy could continue to be absorbed on the basin bottom, water would vaporize, but thermal radiation loss would be reduced. Whether materials with these properties can be found and successfully utilized remains to be seen. 

Preparation of test specimens from solid samples invariably requires a portion of the sample to be cut out, for example, from the middle of the original roll or sheet of material. Freshly cut edges are notoriously high emissions sources and failure to adequately seal these and exclude them from the test is a major potential source of error. (Another advantage of emission test cells versus conventional chambers is that they automatically exclude any potential edge effects in most cases.) Similarly, surface emissions testing requires the rear surface of the material (the surface that will not be exposed once the product is installed in a building) to be sealed and excluded from the test. This is always a consideration for emission test chambers but can be an issue for both cells and chambers in the case of porous or permeable materials. 

Hore importantly, the response curves are noticeably affected where one or both of the components is adsorbable, even at low tracer concentrations. The interpretation of data is then much more complex and requires analysis using the non-isobaric model. Figs 7 and 8 show how adsorption of influences the fluxes observed for He (the tracer), despite the fact that it is the non-adsorbable component. The role played by the induced pressure gradient, in association with the concentration profiles, can be clearly seen. It is notable that the greatest sensitivity is exhibited for small values of the adsorption coefficient, which is often the case with many common porous solids used as catalyst supports. This suggests that routine determination of effective diffusion coefficients will require considerable checks for consistency and emphasizes the need for using the Wicke-Kallenbach cell in conjunction with permeability measurements. 

Apparent Density and Apparent Specific Gravity. Apparent density is the weight of a unit volume of a porous solid including any air which may be entrapped in the pores or interstices (impermeable voids) but not between the grains (permeable voids). This value would be identical with abs d of a material contg no voids (permeable or impermeable), but otherwise it is smaller than the abs d... 

The final cement is an opaque solid that consists of excess zinc oxide coated and bonded by possibly aluminum phosphate and zinc phosphate gels. The cement is porous and permeable to dyes [10]. 

Polymerization of styrene in microemulsions has produced porous solid materials with interesting morphology and thermal properties. The morphology, porosity and thermal properties are affected by the type and concentration of surfactant and cosurfactant. The polymers obtained from anionic microemulsions exhibit Tg higher than normal polystyrene, whereas the polymers from nonionic microemulsions exhibit a lower Tg. This is due to the role of electrostatic interactions between the SDS ions and polystyrene. Transport properties of the polymers obtained from microemulsions were also determine. Gas phase permeability and diffusion coefficients of different gases in the polymers are reported. The polymers exhibit some ionic conductivity. 

This paper reports an investigation of the effects of porous solid structures on their electrical behaviour at different frequencies (from 100 Hz to 100 kHz). For that, we study different parameters such as formation resistivity factor, cementation factor, chargeability, resistivity index and saturation exponent. Different porous solid structures are quantified from the petrographic image analysis and Hg-injection technique. Then, by using different models we obtain the permeability prediction from the electrical behaviour and structure parameters. 

Two models were tested to predict the permeability from the electrical behaviour and microstructure parameters of porous solids. 

Chargeability factor M depends on the brine/gas saturation of porous solids. Figure 3 gives the relationship between the chargeability and brine saturation for two samples. We noted that the M decreases hardly with the decrease of the brine saturation. The presence of vugs and karsts pore types (sample 9-LS8) seems to speed up the decrease of the M Chargeability factor M can be explained by a multi-linear model composed of different structures parameters such as the formation resistivity factor, water porosity, Hg-specific surface area and water permeability, e.g.. Fig. 5. 

Here e(r) is the measured void fraction in pores of radii less than r. The permeability B and the tortuosity K(r) are symmetric second-order tensors according to the preceding two equations they can be predicted as integrals over r and f but are better obtained by fitting Eq. (3.4-11) to material flux measurements for the given porous solid. 

PERMEABILITY A property of a porous solid which is an index of the rate at which a liquid can flow through the pores. See COEFFICIENT OF PERMEABILITY. 

The darcy is a unit for expressing the permeability of porous solids, not area. 

Membrane separation. Here the separation takes place by a selective diffusion of one or more gaseous components across a semi-permeable barrier. In most applications, the membrane is a micro-porous solid, but there are also liquid membranes. The feasibility may be evaluated by using an index of perselectivity aq defined by means of solubility (S/) and diffusivity (D,) ratios as follows ... 

Separation of gases and vapors by means of selective permeable membranes belongs to progressive modem technologies that successfully compete with gas separations by adsorption on porous solids. To compare the influence of different polymer fillers on the properties of heterogeneous membranes. 

Membrane catalytic reactors. Catalytic elements, in the form of membranes thin two-sided layers of a permeable liquid catalyst, or a porous solid catalyst, has the main advantage in its two-sided configurations, so it is possible to design more complex and efficient catalytic reactors, as some, already investigated, or only considered systems ... 

As with liquid flow, the intrinsic permeability Kg with respect to gas flow is a function of only the porous medium. However, the ability of a gas to migrate through a porous medium will depend on the liquid content in the porous medium. When the porous medium is completely diy, Kg represents the continuity of flow through the pores attributable only to the porous solids (i.e., Kg = K). However, as the pores are filled with liquid (e.g., water) such that the percentage of gas-filled pores decreases, the gas may become occluded in some pores such that some of the pathways for gas-phase migration are cut off. When the porous medium is sufficiently saturated with liquid such... 

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