Fractional void volume

Specific gravity is the most critical of the characteristics in Table 3. It is governed by ash content of the material, is the primary deterrninant of bulk density, along with particle size and shape, and is related to specific heat and other thermal properties. Specific gravity governs the porosity or fractional void volume of the waste material, ie. 

Fig. 13.2 Structure of perfluorosulphonic acid co-polymer (Nation ). The Yeager Three Phase Model, based on a three-phase clustered system with interconnecting channels within the polymer. (a) Fluorocarbon backbone, (b) interfacial region of relatively large fractional void volume containing some pendant side chains, some water and sulphate groups, (c) clustered regions...

In the aquifer case, E simply equals the pressure P times the volume of hydrogen gas displacing water in the aquifer. This volume equals the physical volume V times the effective porosity p, that is, the fractional void volume accessible to intruding hydrogen gas (there may be additional voids that the incoming gas cannot reach), so the energy stored may be written... 

Dpm is the mean effective diameter, as defined below e is the fractional void volume of the bed L is the bed height... 

The size distribution and density of inclusion bodies have been studied only for two proteins, calf prochymosin and y-interferon (64). The mean particle sizes of y-interferon and prochymosin inclusion bodies were O.Slgm with a standard deviation of 0.17gm and 1.28gm with a standard deviation of 0.46gm, respectively. The buoyant density of the y-interferon and prochymosin inclusion bodies was proportional to the density of the suspension medium indicating a relatively high voidage within the particles. The void fraction (=void volume/total volume) was 70% for y-interferon and 85% for prochymosin. 

E = fraction void volume of bed, ft, void/ft of packed tower volume volume of void... 

The mean residence time of a phase, which is most important for the degree of conversion in multiphase reactors, is directly related to one of these parameters, i.e. the phase holdup, but in addition, pressure drop and catalyst wetting are also related to holdup. In general, hold-up is expressed either as fractional bed volume C or as fractional void volume p. 

Fractional void volume, or total interstitial porosity H, is defined in terms of the apparent density of the fiber mat, pmat (g/cm ), and bulk density of the polymer, Pp (g/cm ), of which it is made ... 

Deuterium tightly bonded in a-Ge has a wider distribution of configurations than does D in a-Si. The fractional void volume in a-Ge D is larger than in a-Si D samples prepared under similar conditions. The introduction of F reduces the fraction of bonded D in well defined doublet configurations and produces significant amounts of D2 in voids in which the void surfaces have little effect on the D2 relaxation. 

ILLUSTRATIVE EXAMPLE 18.17 Determine the pressure drop of 60°F air flowing through a 3-inch diameter 10-ft packed bed with 0.24-inch protruded catalyst packing made of 316 stainless steel. The superficial velocity is 4.65 ft/s. The protruded packing has a fraction void volume, effective particle diameter and to surface area per unit packing of 0.89, 0.0078.5 ft, and 3305 ft , respectively. 

Specific gravity is an indicator of pOTosity or void volume, since the specific gravity of the solid wood cell wall can be measured at 1.46 -1.54 depending upon measurement technique or approximated at 1.50 [15]. On a dry basis, the porosity, or fractional void volume, can be expressed as follows ... 

Where FVV is fractional void volume (porosity) and So, is specific gravity on an oven dry weight, oven dry volume basis. Typical fractional void volumes are on the order of 60 - 70 percent... 

Like the woody biofuels, the herbaceous biomass forms are porous solids, with significant fractional void volumes. Unlike the woody biofuels, however, the agricultural materials contain significant concentrations of inorganic matter, making the calculation of porosity less precise, and less prone to ready quantification by formula. 

The flow in a packed bed, where the packing may be spherical, c indrical, etc., is quite complex (Figure 6.1.1(b)). However, it is often modeled as a collection of cylindrical capillaries of hydraulic radius R/, and length L, which is the packed bed length. Let e be the fractional void volume of the bed, Op be the total particle surface area per particle volume, v be the actual interstitial velocity in the void volume between particles and dp (= 2rp) be the mean particle diameter. Then the superficial velocity Vo based on the empty cross section of the packed bed is defined as... 

Generally, for rigid spherical particles, the bed porosity or fractional void volume is independent of particle size. Unless the bed length and the bed diameter are vanishingly small (of the order of dp), e is also independent of the bed length L and the bed diameter. Consider now two different packed beds ... 

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