Parallel-flow design

A numerical study of the effect of area ratio on the flow distribution in parallel flow manifolds used in a Hquid cooling module for electronic packaging demonstrate the useflilness of such a computational fluid dynamic code. The manifolds have rectangular headers and channels divided with thin baffles, as shown in Figure 12. Because the flow is laminar in small heat exchangers designed for electronic packaging or biochemical process, the inlet Reynolds numbers of 5, 50, and 250 were used for three different area ratio cases, ie, AR = 4, 8, and 16. 

Barometric condensers are direct contact coolers and condensers. They may be counter flow or parallel flow. Good contact direct cooling is an efficient inexpensive design, being considerably cheaper and more efficient than indirect surface or tubular coolers. 

An 85% free cross section is taken for design purposes. In countercurrent flow, the exit gas is 10-20°C above the solid in parallel flow, the temperature... 

The internal layer flow distribution, or micromanifold, is substantially more challenging an example is shown in Figure 11.2b. A single flow enters a layer that then feeds tens to thousands of parallel channels. Design variables in the micromanifold region before the coimecting process chaimels are an option to control flow distribution [19-23]. 

The existing titanium hydrocyclones are close in design to the units to be provided by the Mozley Company for a full-scale facility in multiple parallel flow units (sometimes called multiclones ). Therefore, the results for the titanium system are anticipated to be similar to those for the Mozley units. 

Kowal et al. [235] used this method to compare the liquid water distribution in the fuel cell with CFP and CC as cathode DLs at different operating conditions and with a parallel flow field channel design for both anode and cathode plates. It was observed that the CFP DL experienced more flooding at lower current densities than the CC, and it retained more water near the landing widths than in or under the channels (60 vs. 40%, respectively). In addition to showing better performance and water removal, the CC resulted in more uniform water coverage on the landing widths and in the channels of the FF. 

Transparent fuel cells are also common tools used to visualize and observe the water accumulation inside FFs and on the surfaces of diffusion layers. Liu, Guo, and Ma [227] tested interdigitated and parallel flow fields wifh CFP DLs. It was observed that the former FF design enhanced the mass transfer when the gas flow was forced to pass through the DL. In fact, the water flooding areas in the interdigitated channels were substantially smaller than in the parallel channel. 

The volumetric flow rates of streams in parallel are designated by Vi, V2 . If V is the flow rate of fluid to the vessel, we then have... 

The 4-ft unit is primarily used to treat soils contaminated with gasoline, diesel, jet fuel, oil, mineral oil, and kerosene. The 5-ft and 6-ft parallel flow LTTD units are designed to treat Bunker C oil, crude oil, and creosote soil contaminants. These plants can also treat soils contaminated with chlorinated hydrocarbons, pesticides, and solvents. 

In a countercurrent dryer the exit temperature of the solid approaches that of the inlet gas. In a parallel current dtyer, the exit gas is 10-20°C above that of the solid. For design purposes the temperature of the exit solid in parallel flow may be taken as 100°C. 

Spray dryers Surface moisture is removed in about 5 sec, and most drying is completed in less than 60 sec. Parallel flow of air and stock is most common. Atomizing nozzles have openings 0.012-0.15 in. and operate at pressures of 300-4000 psi. Atomizing spray wheels rotate at speeds to 20,000 rpm with peripheral speeds of 250-600 ft/sec. With nozzles, the length to diameter ratio of the dryer is 4-5 with spray wheels, the ratio is 0.5-1.0. For the final design, the experts say, pilot tests in a unit of 2 m dia should be made. 

The Jewell-Johnson design provided parallel flow paths for upward... 

In Appendix A, calculations show a status, for fuel cell isothermal Faradaic oxidation, of a high vacuum of reactants relative to a high concentration of product. That calculated status cannot even be approached in the laboratory, for lack of adequate semi-permeable membranes and circulators (concentration cells). The equilibrium fuel cell of Figure A.l is dead-ended, whereas the air-breathing open-ended design must have both of its electrodes swept by a parallel flow, with an inlet and an... 

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