Arrangement factor

Table 3.4 Arrangement factor fE for packings of non-spherical particles...

Eq. (3.270) also holds for packings with non-spherical particles. Values giving some idea of the arrangement factor fs are contained in Table 3.4. The values hold over the range 102 < Re < 104, if the Reynolds number is formed with the effective mean velocity weS = wm/e and an equivalent sphere diameter dP. This is calculated from the mean particle surface area... 

Arrangement factor F for crossflow with square pitchf... 

Diameter, m or ft D, of impeller or scraper D, outside diameter of coil tubing equivalent diameter of noncircular channel D,-, inside diameter of tube of outside of tube Dp, of particle D, inside diameter of exchanger shell D of agitated vessel logarithmic mean of inside and outside diameters of tube Tube arrangement factor for crossflow [Eq. (15.6)]... 

F is an arrangement factor (Table 15d) that varies from... 

The extent to which this radiation heat transfer coefficient varies is readily seen from the nest of curves in figure 2.11, where the coefficient appears as ordinate while the heat exchanging temperatures appear as abscissae and curve parameter labels. The heat transfer coefficients in figure 2.11 are for black body radiation, so they must be multiplied by an emittance factor, F , and by an arrangement factor. Fa, from table 2.3. Tables 4.6,4.7, and 4.8 of reference 51 list many emittances. 

Solution to Example 3.4 For parallel planes, third case on p. 97 of reference 51, find the emissivity factor, Fe, to use with an arrangement factor of Fa = 1.0 in formula 4/la on p. 81 and with a black body radiation rate from the table on page 82, as follows ... 

If you make an error in arranging factors in the calculation (for example, if you use the wrong formula), this will become apparent because the final units will be nonsense. 

Another factor that can be important in the design of evaporators is the condition of the feed. If the feed is cold, then the backward-feed arrangement has the advantage that a smaller amount of liquid must be heated to the higher temperatures of the second and first stages. 

As probes must be manufactured individually for each different tube type, the probe development is an important factor for the economic use of the method. The classical procedure of probe development is a combination of experience and experiment. The new probe design is based on the experience with already manufactured probes. For an evaluation of the new design the probe must be manufactured. If the probe design is complicated, for example due to dual exciter coil arrangement or segmented differential detector coil systems, the costs of the development can be very high. Therefore a method for the pre-calculation of the probe performance is extremely useful. 

At a fixed distance r, the angular factor in equation (A 1.5.12) leads to the greatest attraction when the dipoles are lined up in a linear head-to-tail arrangement, 9 whereas the Imear tail-to-tail geometry, 0 =... 

For interactions between two quadmpolar molecules which have 0 and 0g of the opposite sign, at a fixed separation r, the angular factor in equation (A1.5.13t leads to a linear stmcture, 0 = 0g = 0, being the most attractive. Linear molecules may also prefer a 2 rectangular or non-planar cross arrangement with 0 = 0g = nil, which allows them to approach closer and increase the radial factor. 

Rotary Vacuum Disk Filters. An alternative to the dmm filter is the disk filter, which uses a number of disks mounted vertically on a horizontal shaft and suspended in a slurry reservoir. This arrangement provides a greater surface area for a given floor space, by as much as a factor of 4, but cake washing is more difficult and cloth washing virtually impossible. 

Steric Factors. Initially, most of the coUisions of fluorine molecules with saturated or aromatic hydrocarbons occur at a hydrogen site or at a TT-bond (unsaturated) site. When coUision occurs at the TT-bond, the double bond disappears but the single bond remains because the energy released in initiation (eq. 4) is insufficient to fracture the carbon—carbon single bond. Once carbon—fluorine bonds have begun to form on the carbon skeleton of either an unsaturated or alkane system, the carbon skeleton is somewhat stericaUy protected by the sheath of fluorine atoms. Figure 2, which shows the crowded hehcal arrangement of fluorine around the carbon backbone of polytetrafluoroethylene (PTFE), is an example of an extreme case of steric protection of carbon—carbon bonds (29). 

Eor reverberation room tests of some irregularly shaped items, such as items of furniture, the number of sabins of absorption per item is commonly reported, rather than the absorption coefficient. It is important that the number and arrangement of the items also be reported because both of these factors can affect the results of the test. 

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