Double flow pattern

Flow Pattern In a cyclone the gas path involves a double vortex with the gas spiraling downward at the outside and upward at the inside. When the gas enters the cyclone, its velocity undergoes a redistribution so that me tangential component of velocity increases with decreasing radius as expressed by The spiral velocity in a... 

Superimposed on the double spiral, there may be a double eddy [Van Tongeran, Mech. Eflg., 57, 753 (1935) and Wellmann, Feuer-ungstechnik, 26, 137 (193 ] similar to that encountered in pipe coils. Measurements on cyclones of the type shown in Fig. 17-36 indicate, however, that such double-eddy velocities are small compared with the spiral velocity (Shepherd and Lapple, op. cit.). Recent analyses of flow patterns can be found in Hoffman et al.. Powder Tech., 70, 83... 

Figure 11.21. Liquid flow patterns on cross-flow trays, (a) Single pass (b) Reverse flow (c) Double pass...

Fig. 12 CFD Images of the flow pattern as a function of the static mixer geometry for a periodic section of the reactor top double axe, bottom sieve plates...

Figure 10.15. Some mixers and blenders for powders and pastes, (a) Ribbon blender for powders, (b) Flow pattern in a double cone blender rotating on a horizontal axis, (c) Twin shell (Vee-type) agglomerate breaking and liquid injection are shown on the broken line, (d) Twin rotor available with jacket and hollow screws for heat transfer, (e) Batch muller. (f) Twin mullers operated continuously, (g) Double-arm mixer and kneader (Baker-Perkins Inc.), (h) Some types of blades for the double-arm kneader (Baker—Perkins Irtc.).

Inside the shell sits the tube bundle, in which the tubes are either brazed, welded, or rolled to a circular single or double tube sheet. Typical tube flow patterns are either one, two, four, or six passes. 

The double-pipe mixer was designed and so far only used for contacting and reacting immiscible fluids [134], The respective flow-pattern maps were derived and annular and slug flows as well as complete spread of the inner-tube fluid were identified as distinct regimes. Since in this chapter only miscible liquids are concerned, no protocol and no results are given for the mixer below. H owever, the device is mentioned, since it could in principle be used also for mixing miscible fluids. 

When the Bom, double-layer, and van der Waals forces act over distances that are short compared to the diffusion boundary-layer thickness, and when the e forces form an energy hairier, the adsorption and desorption rates may be calculated by lumping the effect of the interactions into a boundary condition on the usual ccm-vective-diffusion equation. This condition takes the form of a first-order, reversible reaction on the collector s surface. The apparent rate constants and equilibrium collector capacity are explicitly related to the interaction profile and are shown to have the Arrhenius form. They do not depend on the collector geometry or flow pattern. 

Flow Pattern In a cyclone the gas path involves a double vortex with the gas spiraling downward at the outside and upward at the inside. When the gas enters the cyclone, its velocity undergoes a redistribution so that the tangential component of velocity increases with decreasing radius as expressed by V - rt". The spiral velocity in a cyclone may reach a value several times the average inlet-gas velocity. Theoretical considerations indicate that n should be equal to 1.0 in the absence of wall friction. Actual measurements [Shepherd and Lmple, Ind. Eng. Chem., 31, 972 (1939) 32, 1246 (1940)], however, indicate that n may range from 0.5 to 0.7 over a large portion of the cyclone... 

Tar production at different geometries. Experiments during gasification confirmed the importance of correct positioning of the air inlet, with its related double circulary flow patterns, in the throat. While in normal position no tar, e.g. 250 mg/m, was produced, a sharp increase in tar production was observed if the air inlet was moved upwards thus increasing the distance between the inlet and the throat wall. It was also found to be preferable to have the air horizontally flow into the reactor. 

Fig. 36. Snapshots in the nuclidic chart of flow patterns in a ID model of a detonating He layer accreted onto a 0.8M WD. The selected times and corresponding temperatures or densities are given in different panels. The stable nuclides are indicated with open squares. The magic neutron and proton numbers are identified by vertical and horizontal double lines. The drip lines predicted by a microscopic mass model are also shown. The abundances are coded following the grey scales shown in each panel. At early times (bottom left panel), an r-process type of flow appears on the neutron-rich side of the valley of nuclear stability. At somewhat later times (top left panel), the material is pushed back to the neutron-deficient side rather close to the valley of /3-stability. As time passes (two right panels), a pn-process [87] develops...

Figure 7.1 Schematic of a microfluidic LC system. (A) Sample loading (B) sample analysis. 1A and IB, pumping channels 2A and 2B, eluent inlet reservoirs 3, eluent outlet reservoir 4, double-T injector that contains the sample plug 5, separation channel 6, sample reservoir 7, sample waste reservoir 8, sample inlet channels 9, sample outlet channels 10, ESI capillary emitter 11, LC waste reservoir. Note arrows indicate the main flow pattern through the system. (Reprinted with permission from ref. 33).

Preliminary work completed in this project includes laboratory and equipment setup and installation, and preliminary rounds of material optimization and process development. Full size bipolar plate prototypes have been produced with full double-sided flow patterns, demonstrating the potential of the manufacturing process. Process and material development has resulted in the characterization of material properties under a variety of composition levels. Material properties meeting or exceeding DOE targets have been measured, and bipolar plates, both machined and pattern-embossed, have been submitted to UTC Fuel Cells for in and out of cell testing. Phase I work will... 

Scale-up at constant Reynolds number (proportional to ND ) has often been used in an attempt to obtain hydrodynamic similarity. However, the total power consumption in the turbulent region is proportional to N D. Therefore, if the Reynolds number is kept constant but the physiceLL dimensions of the vessel doubled, the total power input will be halved. This gives the same overall flow pattern but not equality of instcintaneous velocities and seems of improbable validity. Scale-up using constant impeller tip speed (= irDN) ensures that the velocities leaving the impellers are the same in each case and has found fairly wide acceptcince. Consteint tip speed means that power input per unit volune ( N D ) falls cis scale is increased but the total power input increases, which is more recisonable. 

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