Permeability interconnected

A microscopic description characterizes the structure of the pores. The objective of a pore-structure analysis is to provide a description that relates to the macroscopic or bulk flow properties. The major bulk properties that need to be correlated with pore description or characterization are the four basic parameters porosity, permeability, tortuosity and connectivity. In studying different samples of the same medium, it becomes apparent that the number of pore sizes, shapes, orientations and interconnections are enormous. Due to this complexity, pore-structure description is most often a statistical distribution of apparent pore sizes. This distribution is apparent because to convert measurements to pore sizes one must resort to models that provide average or model pore sizes. A common approach to defining a characteristic pore size distribution is to model the porous medium as a bundle of straight cylindrical or rectangular capillaries (refer to Figure 2). The diameters of the model capillaries are defined on the basis of a convenient distribution function. 

Monolithic column — The trend to use shorter columns in liquid chromatography means that the resultant lower separation efficiency is of concern. One way to improve HPLC separation efficiency on a shorter column is to reduce the size of the packing material, but at the cost of increased backpressure. Another approach to improve performance is increasing permeability with a monolithic column. Such a column consists of one solid piece with interconnected skeletons and flow paths. The single silica rod has abimodal pore structure with macropores for through-pore flow and mesopores for nanopores within a silica rod8182 (Figure 12.1). 

The subject of study in this case is permeability of regular or irregular 2D and 3D lattices that have some distinctive property. It can be, for example, the lattice of sites formed of different phases, A and B, and the problem is reduced to an establishment of interconnectivity of the system through phase A or B (in one of the phases there can be void). In other examples, there can be problems with the introduction of additional phases that regulate heat transfer or electrical conductivity of the catalyst, or additives, which are introduced into the volume of the catalyst, and further are dissolved or burned off to form a system of transport pores. In the latter case, the percolation approach allows estimations of a volumetric part of the additive that is necessary to form... 

Effective porosity (Ne) is of more importance and, along with permeabihty (the ability of a material to transmit fluids), determines the overall ability of the material to store and transmit fluids or vapors readily. Where porosity is a basic feature of sediments, permeability is dependent upon the effective porosity, the shape and size of the pores, pore interconnectiveness (throats), and properties of the fluid or vapor. Fluid properties include capillary force, viscosity, and pressure gradient. 

All voids in the subsurface medium are classified as porosity. When pore spaces are interconnected so that water can flow between them, the medium is said to be permeable. The actual openings that permit water flow are referred to as effective porosity. Effective porosity is calculated as the ratio of the void spaces through which water flow can occur to the bulk volume of the medium (expressed as a percentage) as follows ... 

Porosity that includes the voids between mineral (or soil) grains is referred to as primary porosity. When the porosity is the result of cracks, fractures, or solution channels, it is known as secondary porosity. The porosity of soft clay is often over 50%, but clay typically has low permeability because the pores are either not interconnected or are too small to permit easy passage of water. On the other extreme, nonfracture igneous rock often has a porosity of less than 0.1% but, again, low permeability. 

On the permeability of membranes with parallel, but interconnected, pathways. Math. Bi-osci. (Bellman Memorial Issue) 77,5-16 (1985). 

Because of the obvious complexity of the controlling factors that may be involved, we shall not attempt at present to estimate their functional magnitude. The existence of interconnecting channels was postulated from scanning electron micrographs of bioleached shale surface (II) and is supported by evidence from the present study. The increase of porosity by removing the carbonate mineral with dilute acid would presumably improve the permeability of certain chemical compounds into and out of the remaining shale structure. 

In the Tbilisi area, the Middle Eocene sequence is a volcanic erupted structure with a very high density of interconnected micro fractures and a relatively smaller number of macro fractures with apertures in the mm range. The matrix rock is of low porosity and low permeability and is not considered to contain any significant reservoir volume. The fields have been producing since 1974 by open-hole wells of which a large number have experienced water break through. 

Porosity The percentage or fraction of openings in a soil, sediment, or rock when compared with the total volume of the material. If the pores are not interconnected, they are not permeable (compare with permeability). 

In CEC, the EOF depends on the column packing structure and pore size of the packing material [51,111-116]. In a packed bed, there are many interconnected channels between particles, which leads to a porous packed structure. The porosity of the packed bed dictates the permeability through the column. The average channel size between particles in a CEC column can be estimated if the packed bed is assumed a... 

Clay and shale have a large number of minute pores, totaling up to 55% of the rock volume. Yet these pores are poorly interconnected, resulting in very low permeability or impermeability (section 2.7). Clay and shale significantly slow infiltration and serve as aquicludes. 

There are many interconnections between the main metabolic pathways. Many substrates and regulatory molecules, and some enzymes, are common to several pathways. An understanding of these interconnections requires knowledge of (1) the subcellular locations and concentrations of the enzymes involved, (2) the concentrations of metabolites within different subcellular organelles, and (3) the nature of permeability barriers for metabolites between the organelles these barriers divide the cell into a number or compartments for each metabolite. 

Whatever the fine structure and reactions associated with hydrating cement paste, the permeability of the hardened matrix will depend on the sizes of interconnected capillary openings remaining after hydration. 

A monolithic column is a single interconnected skeletal stationary-phase support structure consisting of large-flow through-pores (1-3pm). The key to high permeability is that this network support structure can be made in such a way that the ratio of the through-pore size to the skeleton size is much greater than can ever be obtained by a column packed with individual spher-... 

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