Cross channel

The minimum DNB ratio is evaluated at the hottest fuel rod in the hottest flow channel of the core. The fluid conditions in the hottest flow channel of an open-channel PWR should be realistically evaluated by considering the cross-channel... 

HPLC with microchip electrophoresis. Capillary RPLC was used as the first dimension, and chip CE as the second dimension to perform fast sample transfers and separations. A valve-free gating interface was devised simply by inserting the outlet end of LC column into the cross-channel on a specially designed chip. Laser-induced fluorescence was used for detecting the FITC-labeled peptides of a BSA digest. The capillary HPLC effluents were continuously delivered every 20 s to the chip for CE separation. 

The second effect which results from the cross-channel component of the barrel motion is the generation of a wiped film of the polymeric solution as the solution is dragged from the nip in an adjacent screw channel through the clearance between the flight tip and the barrel. Since this film is continually generated, mass is transferred to the gas phase in a time period given by... 

The concentration of the volatile component in the nip is uniform as a result of the cross-channel circulatory motions even though a concentration gradient exists near the vapor-liquid interface. 

Weight fraction of volatile component when bubbles are initially formed Cross-channel coordinate Generalized spatial coordinate Degree of polymerization... 

X independent variable for the cross-channel direction perpendicular to the flight edge... 

For essentially all of the data sets found in Tadmor and Klein [8] the melting results resemble the data shown in Figs. 6.9 and 6.10. The data analysis is of course difficult near the end of melting since the bed often breaks into segments. In essentially ail cases, however, the fraction of the bed remaining in the cross-channel direction (width) is much greater than in the thickness direction. Also, in general the last third of the v-direction material appears to melt in the last turn of the... 

In the classical literature analysis the system equations were manipulated to eliminate V y, the velocity of the solid bed consumption in the thickness direction (y direction), from the analysis by using the assumption that the solid bed reorganizes. This allowed a straightforward differential analysis and a closed form solution in the cross-channel x direction for solids melting. In this analysis, the y-direction velocity V y is retained as a variable because this facilitates the calculation of the change in bed thickness, which was found to be very important in the reevaluation of the literature data, as shown in Figs. 6.9 and 6.10. 

As discussed in Section 6.2.1, the meting process has the potential to generate pressure in the downstream direction. The local pressure affects the melting rate and the compaction of the solid bed and provides a pressure at the entry to the metering section. Here, the dominating pressure is assumed to be the pressure in the melt pool. Cross-channel pressures have been measured as shown in Fig. 12.3, but it is not as important as the pressure in the z direction. This section will develop the equations for the pressure profde in the z direction based solely on the flow in the melt pool. 

When the dissipation due to the cross-channel pressure gradient is included, the rate of loss in the V function is modified as follows ... 

X Independent variable In the cross-channel direction X local width of the solid bed y Independent variable In the channel depth direction Y local thickness of the solid bed In the y direction... 

Elbirli, B., Lindt, J.T., Gottgetreu, S. R., and Baba, S.M., Mathematical Modeling of Melting of Polymers in a Single-Screw Extruder, Polym. Eng. ScL, 24, 988 (1984) Lindt, J.T. and Elbirli, B., Effect of the Cross-Channel Flow on the Melting Performance of a Single-Screw Extruder, Polym. Eng. ScL, 25, 412 (1985)... 

Substituting Eq. 7.18 into Eq. 7.3 and solving Eqs. 7.1 and 7.3 for V, 14, and Vp, the solution for the transformed boundary condition problem Is obtained, and the equations are shown by Eqs. 7.21, 7.23, and 7.26. These equations physically represent the flow due to rotation and pressure in the transformed frame of reference in Fig. 7.10. Equation 7.21 is the velocity equation for the x-direction recirculatory cross-channel flow for the observer attached to the screw, and Eq. 7.23 is the apparent velocity in the z direction for the observer attached to the moving screw. 

Cross-channel velocity in the transformed (Lagrangian) frame ... 

Equation 7.21 is the literature expression for motion in the x direction for barrel rotation physics. The boundary conditions here are = 0 aty = 0 (screw root) and Erf = Kx aty = // (flight tip). Cross-channel velocity in the laboratory (Eulerian)... 

Figure 8.14 Two-dimensional flows in a screw channel with a 6/14 = 1 and operating in extrusion mode. The region shown is the shaded area in Fig. 8.13. Cross-channel flow lines and the corner circulation of the Moffat eddy are visible in the schematic...

X cross-channel direction for an unwound channel system y depth direction for an unwound channel system z downstream direction for an unwound channel system p Newtonian fluid viscosity... 

V relative sliding velocity between a resin and metal surface X independent position variable for the cross-channel direction z independent position variable for the downstream channel direction... 

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