Channel straight

Deniz, S., Greitzer, E. and Cumpsty, N., 1998, Effects of Inlet Flow Field Conditions on the Performance of Centrifugal Compressor Diffusers Part 2 Straight-Channel Diffuser, ASME Paper No. 98-GT-474. 

Furthermore it became clear from the calculations that the diquats will prefer the straight channels of the MFI crystals (Fig. 2). The observed enhanced crystal growth in the b-direction (ref. 4) may be taken as a confirmation of this. 

Figure 2. View of the location of the biquat hexapropyl-l,6-hexanediammonium in a straight channel of the MFI-framework.

Scientists from Politecnico di Milano and Ineos Vinyls UK developed a tubular fixed-bed reactor comprising a metallic monolith [30]. The walls were coated with catalytically active material and the monolith pieces were loaded lengthwise. Corning, the world leader in ceramic structured supports, developed metallic supports with straight channels, zig-zag channels, and wall-flow channels. They were produced by extrusion of metal powders, for example, copper, fin, zinc, aluminum, iron, silver, nickel, and mixtures and alloys [31]. An alternative method is extrusion of softened bulk metal feed, for example, aluminum, copper, and their alloys. The metal surface can be covered with carbon, carbides, and alumina, using a CVD technique [32]. For metal monoliths, it is to be expected that the main resistance lies at the interface between reactor wall and monolith. Corning... 

While the previous studies refer to straight channels exceptionally, microfluidic devices often comprise channels with a curvature. It is therefore helpful to know how hydrodynamic dispersion is modified in a curved channel geometry. This aspect was investigated by Daskopoulos and Lenhoff [155] for ducts of circular cross-... 

GP 10] [R 18]The best HCN yield of 31% at a p-gauze platinum catalyst (70 ml h methane 70 ml h ammonia 500 ml h air 1 bar 963 °C) is much better than the performance of monoliths (Figure 3.49) having similar laminar flow conditions [2]. A coiled strip and a straight-channel monolith have yields of 4 and 16%, respectively. The micro-reactor performance is not much below the best yield gained in a monolith operated under turbulent-flow conditions (38%). 

Monte Carlo simulations and energy minimization procedures of the non-bonding interactions between rigid molecules and fixed zeolite framework provide a reasonable structural picture of DPP occluded in acidic ZSM-5. Molecular simulations carried out for DPB provide evidence of DPB sorption into the void space of zeolites and the preferred locations lay in straight channels in the vicinity of the intersection with the zigzag channel in interaction with H+ cation (figure 1). 

Figure 1. Predicted sorption site of diphenyl-butadiene in straight channel of H5 8ZSM-5 (1DPB/UC)...

DPB as well as other DPP molecules (t-stilbene, diphenyl-hexatriene) with relatively low ionization potential (7.4-7.8 eV) and low vapor pressure was successfully incorporated in the straight channel of acidic ZSM-5 zeolite. DPP lies in the intersection of straight channel and zigzag channel in the vicinity of proton in close proximity of Al framework atom. The mere exposure of DPP powder to Bronsted acidic ZSM-5 crystallites under dry and inert atmosphere induced a sequence of reactions that takes place during more than 1 year to reach a stable system which is characterized by the molecule in its neutral form adsorbed in the channel zeolite. Spontaneous ionization that is first observed is followed by the radical cation recombination according to two paths. The characterization of this phenomenon shows that the ejected electron is localized near the Al framework atom. The reversibility of the spontaneous ionization is highlighted by the recombination of the radical cation or the electron-hole pair. The availability of the ejected electron shows that ionization does not proceed as a simple oxidation but stands for a real charge separated state. 

Figure 5. Some basic structures, from the left to the right straight channel, taper, bend, and Y-junction.

Other important targets for DNS are the turbulent flows at Reynolds numbers up to say 10,000 in simple geometries (such as straight channels or curved... 

The best correlation of the observed isomerization selectivities was found in terms of the diameter of the intracrystalline cavity, determined from the known crystal structure (9) of these zeolites, as shown in Figure 2. While faujasite, mordenite and ZSM-4 all have 12-membered ring ports and hence should be similar in their diffusion properties, they differ considerably in the size of their largest intracrystalline cavity both mordenite and ZSM-4 have essentially straight channels, whereas faujasite has a large cavity at the intersection of the three-dimensional channel system. 

Figure 4.5 View into the pores of the ZSM-5 (MFI) structure along the straight channels (left) and along the sinusoidal channels (right). (Reprinted from D. Kern, N. Schall, W. Schmidt, R. Schmoll, J. Schurtz, Winnacker-Kuchler Chemische Technik, Prozesse und Produkte, Vol. 3, iliciumverbindungen, pp. 849-850. Copyright 2005. With permission from Wiley-VCH.)...

Let us consider a straight channel waveguide with the cross-section schematically shown in Fig. 4. The cross-section can be subdivided by lines parallel with the (vertical) x axis into slices s = 1, 2, S with interfaces positioned at the lateral coordinates y, y2,...,ys i. Each slice is formed by a vertical stack of layers numbered by I, 1 = 1, 2,...,L. In the vertical direction, the waveguide is bound by perfectly conducting electric or magnetic walls positioned at x = Xq and x = x. If need be, they can be substituted by PMLs as described before. 

Figure 4. Cross-section of a straight channel waveguide.

Figure 2.29 Two views of the ten-ring channel system in MWW defined by two-dimensional straight channels with ten-ring pores that open into large cavities with inner free diameters of 0.71 nm and inner free heights of 1.82nm.

Figure 1. Local current density profiles along a straight-channel fuel cell as predicted by the same computer model for two cases differing only in two model parameters. ...

Figure 9. Membrane water content (A) distribution in a three-straight channel fuel cell (only the half cell is shown due to symmetry) with anode and cathode counter-flow at 0.65 V or average current density of 1.1 A/cm. Anode and cathode feed conditions are humidification temperature = 50 °C, pressure = 2 atm, stoichiometry = 2, and the cell temperature = 80 °C.

Figure 12. Temperature distribution (in K) in tbe middie of the membrane (EW < 1000) for a straight-channel PEM fuel cell (cell voltage = 0.6 V, average current density = 1.42A/cm2) with a cell temperature of 80 °C.

Among the three heat-generation terms, the irreversible and reversible heat sources of ORR are dominant. For a straight-channel cell shown in Figure 12, the total amount of heat release is 2.57 W, of which the irreversible heat is 55.3%, the reversible heat 35.4%, and the Joule heat only 9.3% The total heat released from the fuel cell can also be estimated from the overall energy balance, i.e. 

Figure 14. Current distribution in a straight-channel fuel cell at a cell voltage of 0.6 V (a) without GDL electronic resistance and (b) with GDL electronic resistance.

Figure 15. Current density profiles as a function of the flow plate electric conductivity (S/m) in a straight-channel fuel cell with an average current density of 0.8 A/cm. ...

---