Porosity connected

Ferrous chloride (4H2O) [13478-10-9] M 198.8, m 105°(dec), pKj 6.7, pKj 9.3 (for aquo Fe " "). A 550mL round-bottomed Pyrex flask was connected, via a glass tube fitted with a medium porosity... 

There are essentially four important physical parameters that characterize a filter media and are used as a basis for relating the characteristics of the material to the system flow dynamics. These are porosity, permeability, tortuosity and connectivity. 

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. 

Absolute porosity—. oH porosity of a rock, regardless of whether or not the individual voids are connected. 

In this connection the remaining oil in the separator plays an important role. At the first glance, to increase the porosity a total extraction of the oil would be expedient, but certain oil components have been shown to exert a protective action on the polyethylene. Oil content and its distribution, as well as selection of the oil, thus gain particular significance [41, 52-54]. 

Both dynamic melting and equilibrium transport melting require that the porosity when two nuclides are fractionated from one another is similar to the size of the larger of the partition coefficients for the two nuclides. Given the low values of the experimental determinations of Du and Dxh, the porosities required to explain the observational data in these models are generally less than 0.5% and often times closer to 0.1%. Such low porosity estimates have been criticized based on physical grounds given the low estimated mantle permeability derived from the extent of melt connection observed in experiments (Paul 2001). 

Porosity bears but little connection to permeability. The permeability is a measure of the rate of diffusion of liquids and gases through the refractory. It is understandable that the... 

Figure 2.9.3 shows typical maps [31] recorded with proton spin density diffusometry in a model object fabricated based on a computer generated percolation cluster (for descriptions of the so-called percolation theory see Refs. [6, 32, 33]).The pore space model is a two-dimensional site percolation cluster sites on a square lattice were occupied with a probability p (also called porosity ). Neighboring occupied sites are thought to be connected by a pore. With increasing p, clusters of neighboring occupied sites, that is pore networks, begin to form. At a critical probability pc, the so-called percolation threshold, an infinite cluster appears. On a finite system, the infinite cluster connects opposite sides of the lattice, so that transport across the pore network becomes possible. For two-dimensional site percolation clusters on a square lattice, pc was numerically found to be 0.592746 [6]. 

The theory on the level of the electrode and on the electrochemical cell is sufficiently advanced [4-7]. In this connection, it is necessary to mention the works of J.Newman and R.White s group [8-12], In the majority of publications, the macroscopical approach is used. The authors take into account the transport process and material balance within the system in a proper way. The analysis of the flows in the porous matrix or in the cell takes generally into consideration the diffusion, migration and convection processes. While computing transport processes in the concentrated electrolytes the Stefan-Maxwell equations are used. To calculate electron transfer in a solid phase the Ohm s law in its differential form is used. The electrochemical transformations within the electrodes are described by the Batler-Volmer equation. The internal surface of the electrode, where electrochemical process runs, is frequently presented as a certain function of the porosity or as a certain state of the reagents transformation. To describe this function, various modeling or empirical equations are offered, and they... 

Acidic micro- and mesoporous materials, and in particular USY type zeolites, are widely used in petroleum refinery and petrochemical industry. Dealumination treatment of Y type zeolites referred to as ultrastabilisation is carried out to tune acidity, porosity and stability of these materials [1]. Dealumination by high temperature treatment in presence of steam creates a secondary mesoporous network inside individual zeolite crystals. In view of catalytic applications, it is essential to characterize those mesopores and to distinguish mesopores connected to the external surface of the zeolite crystal from mesopores present as cavities accessible via micropores only [2]. Externally accessible mesopores increase catalytic effectiveness by lifting diffusion limitation and facilitating desorption of reaction products [3], The aim of this paper is to characterize those mesopores by means of catalytic test reaction and liquid phase breakthrough experiments. 

A container of V = 50 cc is loaded with W = 53 g of porous pellets. It is first evacuated then connected to a supply of helium. A gas volume V +Vg = 29 cc is introduced this way. V is the volume between the pellets and Vg is that of the pores. Then mercury is introduced, the amount to fill the spaces between the pellets being Vg = 19 cc. Find the true density and the porosity of the pellets. 

Many gallophosphate molecular sieves are unstable to calcination in air or in the presence of moisture, which limits the utility of these materials because at room temperature (RT) the templates stuff the channels thus limiting access to the porosity. The ULM-16 structure is interesting because it is stable to 800°C under argon and up to 350-400°C in the presence of oxygen. This stability may reflect the fully connected framework of ULM-16. 

The quantity of water that can be retrieved from a medium is related to size and shape of the connected pore spaces within that medium. The quantity of water that can be freely drained from a unit volume of porous medium is referred to as the specific yield. The volume of water retained in the medium by capillary and surface active forces is called the specific retention. The sum of specific retention and specific yield is equal to the effective porosity (see Table 3.4). Neither term has a time value attached. Drainage can occur over long periods (i.e., weeks or months). 

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