Flow, recirculating

Figure 5 shows the variation of the droplet mean axial velocity at the same axial location. The primary feature of this velocity profile is that the maximum velocity peaks at the centerline. The velocity magnitude and direction in the center region tend to be related to the hquid swid strength and axial distance. A reverse (recirculation) flow with negative velocity is possible if the swid is intense. Under such conditions, the maximum velocity tends to shift away from the centerline. 

At 0119 10, the operator began to increase the rate of feedwater return to reduce the recirculation flow to increase the water level in the steam drums. At 0119 45, the reduced inlet water. stopped water from boiling in the core. The absence of the steam voids reduced the reactivity, and control rods were withdrawn, such that only 6 to 8 rods were in the reactor, rather than the required 30. Then, to avoid reactor trip from steam drum or feedwater signals, their scram circuils v ere locked out (a safety regulation violation). 

FIGURE 8.3 Model of a local recirculating system with a local exhaust hood, used for calculating the connection between contaminant concentrations, airflow rates, contamirtartt source strength, q , air cleaner efficiency, n and hood capture efficiency, a. is the concentration in the supply (outside) air c (equal to c h) is the concentration in the room Is the concentration in the returned air is the supply flow rate to the room equal to the exhaust flow rate, the recirculated flow rate (through the cleaner) is T is the time constant for the room and V is the room volume. 

In ref. 38 the k-co model was used to predict low-Reynolds-number, recirculating flow. 

David.son, L, Large eddy simulation A dynamic one-equation subgrid model for three-dimensional recirculating flow. In llth Int. Symp. on Turbulent Shear Flow, vol. 3, pp. 26.1-26.6, Grenoble, 1997. 

This unit is usually used as the reboiler for the distillation column and, in this service, operates by the thermosiphon action of the difference in static head in the column and in the vapor-liquid phase leaving the reboiler. When tied into the bottom chamber, the liquid is usually recirculated many times, vaporizing only 10-25% of the reboiler feed per pass however, when used as a draw-off from the bottom tray seal pan, the feed to the reboiler is not recirculated flow. The basic operation is the same, however. 

The recirculation ratio for a unit is the lb rate of liquid leaving the outlet compared to the lb rate of vapor leaving. The liquid recirculation flow rate entering the unit is set by the differential pressure driving the system. 

Morinda citrifolia recirculating flow capillary laminar/turbulent membrane integrity morphology non-growth [54, 120]... 

Qian and Bau [144] have analyzed such electroosmotic flow cells with embedded electrodes on the basis of the Stokes equation with Helmholtz-Smoluchowski boimdary conditions on the channel walls. They considered electrode arrays with a certain periodicity, i.e. after k electrodes the imposed pattern of electric potentials repeats itself An analytic solution of the Stokes equation was obtained in the form of a Eourier series. Specifically, they analyzed the electroosmotic flow patterns with regard to mixing applications. A simple recirculating flow pattern such as the one... 

Harris, P.C. Harms, W.M. Norman, L.R. "Study of Continuously Mixed Crosslinked Fracturing Fluids With a Recirculating Flow Loop Viscometer", SPE paper 17044, 1987 SPE Eastern Regional Meeting, Pittsburgh, October 21-23. 

To continuously separate FT wax products from ultrafine iron catalyst particles in an SBCR employed for FTS, a modified cross-flow filtration technique can be developed using the cross-flow filter element placed in a down-comer slurry recirculation line of the SBCR. Counter to the traditional cross-flow filtration technique described earlier, this system would use a bulk slurry flow rate below the critical velocity, thereby forcing a filter cake of solids to form between the filter media and the bulk slurry flow, as depicted in Figure 15.2b. In this mode, multiple layers of catalyst particles that deposit upon the filter medium would act as a prefilter layer.10 Both the inertial and filter cake mechanisms can be effective however, the latter can be unstable if the filter cake depth is allowed to grow indefinitely. In the context of the SBCR operation, the filter cake could potentially occlude the slurry recirculation flow path if allowed to grow uncontrollably. 

Figure 2.22 [2.6] demonstrates the method of a cooling circuit with recirculated flow An injector pump operated with just evaporated LN2 aspirates the warmer N2 coming from the condenser and feeds the mixture back in the condenser. The desired condenser temperature can be controlled by a throttle valve. To achieve a uniform temperature distribution, the gas mixture is alternately fed to one or the other end of the condenser. No results of such a system are given. 

Suppose the bottom temperature of the liquid is maintained at 25 °C for a thin pool. Let us consider this case where the bottom of the pool is maintained at 25 °C. For the pool case, the temperature is higher in the liquid methanol as depth increases. This is likely to create a recirculating flow due to buoyancy. This flow was ignored in developing Equation (6.33) only pure conduction was considered. For a finite thickness pool with its back face maintained at a higher temperature than the surface, recirculation is likely. Let us treat this as an effective heat transfer coefficient, between the pool bottom and surface temperatures. For purely convective heating, conservation of energy at the liquid surface is... 

For a recirculating flow like this, the fluid s destination is the same as its origin so the two locations can be chosen to be the same, for example the point marked X. In this case equation 1.14 reduces to... 

It is important to be aware of the fact that most turbulence models have been developed for and validated against turbulent shear flows parallel to walls. Models for separated and recirculating flows have received much less attention. The turbulent impinging jet shown in Fig. 4.6 is a good example of a flow used to test the shortcomings of widely employed turbulence models. The unique characteristics of this flow include the following.16... 

Anand, M. S., S. B. Pope, and H. C. Mongia (1989). A PDF method for turbulent recirculating flows. In Turbulent Reactive Flows, Lecture Notes in Engineering, pp. 672-693. Berlin Springer-Verlag. 

The vertical mixing is enhanced using a baffle system. This uses the gas lift principle on the front face to increase upward liquor flow. A corresponding downward flow of gas-free liquor is drawn down the back face of the baffle thus creating an increased vertical circulation. Measurements at the test facilities of ICIETB have demonstrated a recirculation flow ratio of recirculated flow to inlet flow of approximately 70 1, depending on the operating current density. 

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