Comer flows

Fig. 6 Schematics of (a) No-slip flow and slip flow, (b) Film flow (i) and (2) are immiscible fluids, (c) Comer flow in a rectangular channel...

In a two-phase flow system, the different affinity of the two fluids for the wall makes (me fluid preferentially flow along comers due to the capillarity. As the number of the polygon sides decreases and the comers sharpen, the cross-sectional area of fluids held in comers increases, and comer flow becomes more important. Therefore, comer flow must be considered carefully in such processes as evaporation and drying of micro- and nanochannels with small angular polygonal cross sections. 

Example 5.4 Eight polypropylene mouldings, each weighing 10 g are to be moulded using the runner layout shown in Fig. 5.19. If the injection time is 2 seconds and the melt temperature is 210°C, calculate the pressure at each cavity if the injection pressure at the sprue is 80 MN/m. The density of the pwlypropylene is 909 kg/m3 and the volume of the sprue is 5000 mm. Assume that the flow is isothermal and ignore the pressure losses at comers. 

For the sake of developing commercial reactors with high performance for direct synthesis of DME process, a novel circulating slurry bed reactor was developed. The reactor consists of a riser, down-comer, gas-liquid separator, gas distributor and specially designed internals for mass transfer and heat removal intensification [3], Due to density difference between the riser and down-comer, the slurry phase is eirculated in the reactor. A fairly good flow structure can be obtained and the heat and mass transfer can be intensified even at a relatively low superficial gas velocity. 

The dissipated energy due to flow resistance and turbulence F consists of four parts the energy consumption in the riser, that in the separator tubes, X that in the down-comer, and that due to the flow direction changes of the U-bending channel at the top and bottom of the reactor,/,. Therefore, F can be written as ... 

The basic layout and flow arrangement for a gasketed plate heat exchanger is shown in Figure 12.60. Comer ports in the plates direct the flow from plate to plate. The plates are embossed with a pattern of ridges, which increase the rigidity of the plate and improve the heat transfer performance. 

The distribution of anesthetic throughout the entire body may be viewed as an equilibration process (Fig. 7.1.13), with tissues characterized by high blood flows reaching equilibration faster than muscle and fatJ4 Nevertheless, an anesthetic that is excessively soluble in blood will not partition substantially into brain and other tissues. The anesthetic properties of nitrous oxide and diethyl ether have been known since the 1840s. Zeneca Pharmaceuticals introduced the first modem inhalation anesthetic fluothane in 1957. Methoxyfluorane followed in 1960, enflurane 1973, isoflurane 1981, desflurane by Anaquest (Liberty Comer, NJ) in 1992, and sevoflurane by Abbott Laboratories in 1995J6 ... 

D flows and time-dependent 2D flows, and mixes the fluid by continuously stretching different volumes of the fluid and folding them into one another. In a qualitative sense, the path taken by a given fluid element in the flow depends in a sensitive way on its encounters with a series of weak secondary flows or eddies, present even at low Re in the comers of channels, which transport the element across the flow [167],... 

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. 

The down-comer from the gas/liquid separator that collects the liquid slurry product is connected to the suction side of a moyno-type (Liberty progressive cavity) pump. The pump discharge is connected to a primary separation device (an inertial separator similar to a hydrocyclone). Since the slurry pump is a positive displacement device (i.e., no slurry slippage inside the pump), the total flow... 

Effectiveness of clearance. Where the general level of air flow at the workstation is poor, as in a comer, the less effective is the general ventilation. 

The technology question can be answered quite readily, but the question about Away while not at first apparent is often the most important point of the discussion. On almost every process flow sheet or process development schematic, there is a little truck down at the lower right hand comer for waste disposal. This is the Away . Years ago, we assumed that the wastes would be taken care of and disposed properly. But because they... 

Comer, E. and Organ, M.G. (2005). A Microreactor for Microwave-Assisted Capillary (Continuous Flow) Organic Synthesis. J. Am. Chem. Soc., 127, 8160-8167. 

The model results show the velocity profile of a FCCU flue gas traveling vertically upward then making a 90° turn leading to the SCR. Notice the uniformity of the stream velocity as it travels upward. As soon as the stream encounters the 90° turn, the velocities stratify with nearly stagnant flow at the comer, and very high velocities at the far wall. This occurs because the denser catalyst particles are carried out further in the duct by their momentum relative to the lighter gas molecules. 

It was stated by Evans Ablow (Ref 66, p 162) Although, as has been observed in previous sections, the shock is curved when the flow diverges, near the axis it is plane. Jones (our Ref 18a) approximated the divergence of the flow near the axis by that in the Prandtl- Meyer expansion around a comer a distance half a diameter (d/2), from the axis. He assumed the Abel equation of state, complete reaction, and the plane form of the C J condition... 

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