Pressure differential across fabrics

Van der Linden, Wassink and Theusink, have recently reported on a novel technique for mechanically extracting water though the use of a pressure differential across fabrics which is on the order of 0.5 atmospheres (6). The pressure differential is developed by either throttling high pressure steam (6 atm.) or compressed air through a one-mil wide nozzle (Machnozzle). Steam is usually employed since the nozzle operates isoenthaipically,... 

Even more recently, European work has led to significant advances in the scaleup of air cathodes, with pilot electrolyzers operating at less than 2.5 V at a current density of 6kAm [20]. With full-sized cathodes, there is a fundamental issue of adjusting the local differential pressure between the caustic and the oxygen compartment on the other side of the electrode. Because of the porous nature of the GDE, a pressure balance across the electrode must be established in order to avoid excessive flow from one side to the other. As shown in Fig. 17.4, there is a restricted range of differential pressure within which the electrode works properly. This new set of constraints has required new developments in electrode structure and fabrication [21]. 

The actual basis for separation can be the differential solubility in the membrane material or the membrane hole size. When separating gases hollow membrane fibres are popular, as the small diameter of the fibres allows than to withstand the substantial driving pressures involved. Separation of the components in liquid systems usually relies on some form of spirally wound membrane sheet and spacer. Once again, substantial differential pressures are involved across the membrane surface and this conventionally requires the use of some form of spacer to prevent closure of the channels. Not only do these spacers (e.g. coarse woven fabric)... 

Most cyclones are designed with flat roofs. Under high pressure or high vacuum conditions, however, it is sometimes necessary to fabricate a cyclone with a domed roof. Typically, such a roof is either elliptical or hemispherical— depending on such factors as the differential pressure across the roof, wall thickness, the size of the cyclone, and the relative vortex finder-to-barrel diameter. In such instances, it is recommended that a fiat false or inner roof be installed (and properly vented if necessary) so that the flow pattern is the same as that of a conventional flat-headed cyclone. 

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