Tube Orientation

At high condensing loads, with vapor shear dominating, tube orientation has no effect , and Eq. (5-lOCU) may also be used for horizontal tubes. 

Readings given by open straight tubes (Fig. 10-ld and le are too low due to flow separation. Readings of closed tubes oriented perpendicularly to the axis of the stream and provided with side openings (Fig. 10-lg) may be low by as much as two velocity heads. 

Coil Design Indirect-fired equipment is conventionally classified by tube orientation vertical and horizontal. Although there are many variations of each of these two principal configurations, they all are embraced within seven major types, as follows. 

In a previous experimental study, Wphni and Stranden (1979) also investigated the relationships between the film badge response at the neck (located at the right-hand side of the thorax) and jF/e for various fluoroscopic conditions, including both over- and undertable x-ray tube orientations. The amount of scatter radiation observed from undertable orientation was less than from overtable orientation, while the distribution of the scatter radiation from undertable orientation was skewed towards the lower body, which can be shielded by protective devices located on the fluoroscopic system (Faulkner and Moores, 1982),... 

From the Wphni and Stranden study, the increase in the ratio of to the film badge response for undertable orientation is observed to be fairly constant. For the combination of kVp and equivalent lead thickness of the apron that corresponds to the overtable limiting condition, the increase in this ratio is a factor of 1.6. A revised limiting minimum ratio that includes consideration of both underand overtable x-ray tube orientations would be 5.6 (i.e., the minimum value for the overtable case of 8.9 divided by 1.6). 

Figure 12 presents the cross section of the four consfrucfed CPCs. The collectors were mounted in parallel on a single structure to facilitate the comparison. This structure was oriented facing south with inclination equal to the local latitude (19°) and tubes oriented east-west (Figure 13). Each reactor processed 3 L of wafer in fhe recirculafion batch mode.

MalhpR., 1998, Role of 1,4,5-inositol trisphosphate-induced Ca 2+ release in pollen tube orientation. Sex. Plant Reprod. 11 231-235. 

The differences from the earlier rod based description are most striking in the case of the Cg structure. One interesting feature of this structure is the occurrence of (infinite) helical tubes oriented parallel to the four [111] directions of the cubic unit cell. 

Figure 6.1 Effect of velocity ratio on concentration ratio for a sampling tube oriented in the direction of the mainstream flow. The curves are approximate representations of the data of various experimenters for unit density particles of diameters (in /rn i) as indicated. The displacement of the point tig/iita = 1 from = I results from the finite particle diameter. The curves apply to a...

For the interfacial shear-controlled flows, annular film flow pattern is established, and the tube orientation is irrelevant. Consequently, the correlations for annular condensation in horizontal tubes can be applied for vertical internal downward flows as well—see Table 17.25. 

If the reactor is not vertical, there is no longer a question of stability - there is always convection. Bazile et al. studied descending fronts of acrylamide/bisacrylamide polymerization in DMSO as a function of tube orientation (39). The fronts remained nearly perpendicular to the vertical but the velocity projected along the axis of the tube increased with a 1/cos 0 dependence. 

Experiments on the yellow wave propagation at different tube orientations were carried out by Das et al. [71]. Results revealed that the location of bands in the horizontal tube (H) was approximately half-way between those in the and directions. 

In equation 76a the reptation time A,rep is the time for the chain to escape from the tube (orientation relaxation occurs from the end to the center of the chain). Gn is the entanglement plateau modulus (this value is slightly different from that implied from rubber elasticity of an entangled network) and f pit) is a normalized relaxation modulus for the reptation process. In this time regime, equation 76a implies that the modulus is separable into a time fimction and a modulus function. This becomes important in discussing the nonlinear response, which is done, in more detail, below. Some other viscoelastic functions from the DE tube model of reptation are... 

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