Pore space within

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). 

The solids density Ps is the density of fhe solid material from which fhe parficle is made and excludes any pore spaces within the particle. It can be measured using a specific gravity bottle and a liquid in which the particle does not dissolve. The envelope density of a particle is that which would be measured if an envelope covered the external particle surface, i.e. it is equal to the particle mass divided by the external volume. In most analyses the envelope and solids densities are assumed to be equivalent. The bulk density of a powder ps is the effective density of the particle bed defined by... 

Thus gas, if any is present, is found in the highest parts of the trap, followed by oil (and oil with gas) below the gas, and finally salt water below the oil. Experience has indicated that the salt water seldom was completely displaced by oil or gas from the pore spaces, even w ithin the trap. Even in the midst of oil and gas accumulation, pore spaces within the trap may contain from 10 to 50% or more of salt water, It appears that the remaining water (termed connate water) fills the smaller pores ancl also exists as a coating or film, covering the rock surfaces of the larger pore spaces thus oil and/or gas are apparently contained in water-jacketed pore spaces. The geological structures called traps are petroleum reservoirs, i.e.. they are the oil and gas fields that me explored and produced. All oil fields contain some gas, but the quantity may range widely. See also Natural Gas. 

Lens-Type Traps. These form in limestone and sand. In this type of trap the reservoir is sealed in its upper regions by abrupt changes in the amount of connected pore space within a formation. A trap formed in sand is shown in Fig, 7(a). An example is the Burbank Field in Osage County, Oklahoma. This type of trap may occur in sandstones where irregular deposition of sand and shale occurred at the time the formation was laid down. In these cases, oil is confined within the porous parts of the rock hy the nonporous parts of rock surrounding it. A lens-type trap formed in limestone is shown in Fig. 7(b). In limestone formations there are frequent areas of high porosity with a tendency to form traps. Examples of limestone reservoirs of this type are found in the limestone fields of West Texas. 

In general, most soil and rock minerals are electrical insulators (high resistivity) and, as a result, the flow of current is conducted primarily through the moisture-filled pore spaces within this matrix. Therefore, the resistivity of soils and rocks is predominantly controlled by the amount of pore water, the porosity and permeability of the system, and the concentration of dissolved solids in the pore water. 

Brook et al. (1990) found pollen grains incorporated in the pore spaces within the speleothem fabric. Since the age of the encapsulating calcite could be determined by U/Th methods, the age of the pollen could also be determined far beyond the usual limitation of carbon-14 dating. From pollen speciation in speleothems. Brook et al. concluded that the Chihuahuan Desert of southwestern United States and the Kalahari Desert of northwestern Botswana were wetter during northern hemisphere glacial and interstadial times. In contrast, wetter conditions in the Somali-Chalbi Desert corresponded with interglacials and to a lesser extent with interstadials. 

A low surface tension value correlates with a small contact angle. The binder with the smaller contact angle has improved spreadabiiity and can wet powders more effectively (65,84). A surfactant can also be added to the binder solution to improve wettability, especially for hydrophobic powders, and functions to lower both the surface tension as well as the contact angle of the liquid. If the contact angle, 6, is less than 90, then the powder wetting is spontaneous. However, if the contact angle is closer to 180 then the powder would be considered unwettable by the liquid. The pore space within a particle assembly can be simplistically considered as a model capillary. The capillary pressure, Pc, of a liquid is related to the surface tension by the following equation ... 

Once the specific magnetization intensity is determined, Eq. (24) is used to relate the intrinsic magnetization to the mass of fluid within the porous media sample. Since we assume that the sample is fully saturated, this quantity is considered to be the pore space within the sample and is used in Eq. (3) to determine the porosity, 0 , corresponding to voxel j ... 

Figure 9. The menger sponge a potential fractal representation of pore space within FCC particles. ( fractal dimension = 2.7268) [15]...

The adsorption of water from a binary or multicomponent liquid mixtures is characteristically different from that from gaseous phase because the pore space within the alumina is always filled with a liquid mixture. Nevertheless, the key characteristics (equilibria, kinetics and ad(de)sorption column dynamics) for adsorption of trace and bulk water from a liquid mixture is very well studied. 

The porosity (([)) characterizes the relative amount of pore space within a sample volume. It is defined by the ratio... 

Consider now an adsorbent that offers little or no resistance to mass transfer because it is "macroporous." This means that the pores within the solid are large (macro), that is, greater than 20 nm in diameter or width, and that transport of small molecules (0.2 nm) is unhindered and takes place as if they were in the bulk phase surrounding the solid. This means that the bulk gas phase concentration is the same in the pore spaces within the solid as it is outside the solid. 

As described earlier, the sub-surface region of the earth comprises the unsaturated zone and the saturated zone. The boundary between the two zones is represented by the water table, and the region immediately above the water table is the capillary zone, where pore spaces within the unsaturated zone may be saturated by water rising from the water table under capillary forces. 

The porosity, n, of a rock can be defined as the percentage pore space within a given volume and is expressed as follows ... 

The early oil production experts were well aware of this effect. Indeed, Herold (7), in a comprehensive book dealing with mechanisms of oil production, bases his entire description of Paleozoic production (half of the book) on the fact that oil and gas are distributed uniformly as tiny droplets of oil and little bubbles of gas (he ignores water) which occur in sequence through all pore space within the rock. Just as Jamin (6) found that a series of gas bubbles in a perfectly smooth capillary tube could build up large resistances to flow, Herold (7) pointed out that... 

Mesoscale modeling of SOFCs focuses on modeling the transport and reactions of gas species in the porous microstructures of the electrodes [3, 34, 56-59]. In these models, the porous microstructure is explicitly resolved, which negates the need for the effective parameters of macroscale models. The transport and reactions of species in mesoscale models are described by the species [Eq. (26.1)], momentum [Eq. (26.5)], and energy [Eq. (26.7)] conservation equations, which are solved at the pore scale. At the pore scale, the conservation equations are solved in two separate domains the solid domain of the tri-layer and the gas domain of the pore space within the tri-layer. Mesoscale models aim to understand the effects of microstructure and local conditions near the electrode-electrolyte interface on the SOEC physics and performance. These models have been used to investigate a number of design and degradation issues in the electrodes such as the effects of microstructure on the transport of species in the anode [19, 56] and the reactions of chromium contaminants in the cathode [34]. 

Tricalcium silicate hydrate (tobermorite gel) is the compound most responsible for the mechanical strength and dimensional stability of the hardened concrete. The pore space within the hardened concrete leading to its adsorption, porosity, and drying shrinkage is the result of the tobermorite gel structure. 

Another benefit of crystalline metal oxides is that their high conductivities allow charge propagation along the lattice structures of thin surface layers. However, conductivity is lower in the commonly used hydrous metal oxides that are amorphous. It is possible to increase conductivity through crystallization but this significantly reduces active surface area via the removal of water and elimination of pore spacing within the material structure [79]. 

In Sections 15.2 through 15.6, the terminologies macropores and micropores are based on that used in porous electrode theory, with the term macropores denoting the electrolyte-filled continuous interparticle space in between carbon particles, serving as transport pathways for ion transport across the electrode, whereas the term micropores is used for all the pore space within the carbon particles (intraparticle porosity see Figure 15.5b). In Section 15.7, the formal lUPAC terminology for porous material characterization is used where macro-, meso-, and micropores are distinguished on the basis of the pore sizes in a porous material. ... 

The fact that the polymer dispersion coefficient is larger over a range of flow rates for the low-concentration xanthan/tracer floods is shown in Figure 7.4. In this low-concentration flood, the chloride dispersion coefficient is almost identical to the value found experimentally in the absence of polymer. Thus, it can be concluded that the presence of polymer, at least in low concentration, has no effect on the passage of the chloride (an inert tracer) through the tortuous pore space within the sandstone core. However, there is clearly an effect at play which causes the xanthan dispersion to be larger than that of the chloride. 

The process of leaching when applied to the measurement of pore-water compositions is essentially very simple. A leaching solution, normally deionized water, is applied to the sample in such a manner that it accesses the pore space within the rock material, mixing with the pore-water or dissolving residual solutes of the pore-water if the sample has been dried first. The leaching solution is then separated from the rock matrix and analysed for the chemical components extracted from the pore-water. 

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