Screening surface area

An electrically heated long solid rod is to be used for the heating of an industrial building. A screen with a ratio of total hole area to total apparent (holes + screen) surface area of n — 0.9, and inner and outer emissivities of = 0.08 and = 0.9, is to be placed around the heater to shield the surroundings from the hot surface of the heater (Fig. 9.28). The ambient temperature is Too - 27 °C. Assume the heater radius to be rw = 1 cm, emissivity = 0.8, the energy generation = 3 MW/m5, and the radius of screen to be r, = 3 cm. Neglecting the effect of convection, we wish to determine (a) the increase in the surface temperature of heater and (b) the screen temperature. 

Prediction of various physicochemical properties such as solubihty, lipophhicity log P, pfQ, number of H-donor and acceptor atoms, number of rotatable bonds, polar surface area), drug-likeness, lead-likeness, and pharmacokinetic properties (ADMET profile). These properties can be applied as a filter in the prescreening step in virtual screening. 

Fibrillated Fibers. Instead of extmding cellulose acetate into a continuous fiber, discrete, pulp-like agglomerates of fine, individual fibrils, called fibrets or fibrids, can be produced by rapid precipitation with an attenuating coagulation fluid. The individual fibers have diameters of 0.5 to 5.0 ]lni and lengths of 20 to 200 )Jm (Fig. 10). The surface area of the fibrillated fibers are about 20 m /g, about 60—80 times that of standard textile fibers. These materials are very hydrophilic an 85% moisture content has the appearance of a dry soHd (72). One appHcation is in a paper stmcture where their fine fiber size and branched stmcture allows mechanical entrapment of small particles. The fibers can also be loaded with particles to enhance some desired performance such as enhanced opacity for papers. When filled with metal particles it was suggested they be used as a radar screen in aerial warfare (73). 

ASTM recognizes two types of zinc dust in specification ASTM D 520-51 (reapproved 1976) (143), which includes permissible impurity concentrations. The metallic content of most commercial grades is 95—97%. The zinc oxide content is between 3 and 5% finer dusts contain higher concentrations because of high surface areas. Zinc dusts are manufactured in various size ranges, and a typical commercial dust has an average particle diameter between 4 and 8 p.m. Usually, dusts are screened to be essentially free of particles coarser than 75 p.m (200 mesh). 

Screen Surfaces The selection of the proper screening surface is veiy important, and the opening, wire diameter, and open area should all be carefully considered. The four general types of screening surfaces are woven-wire cloth, silk bolting cloth, punched plate, and bar or rod screens. 

Power Requirements The power required in jigging depends on the screen area, the size of material treated, the percentage of opening in the jig screen, the depth of the bed, the length of stroke, and the choke frequency. The power required for plunger-type jigs treating 12.7-mm 0/ -in) material is about 7 W/m" (0.1 hp/ft") jig screen surface. 

Although a correlation between BET surface areas from 77 K nitrogen isotherms and methane uptake at 298 K and 3.5 MPa has been shown for many carbon adsorbents, [11, 20], deviations from this relationship have been observed [20]. However, as a primary screening process for possible carbonaceous adsorbents for natural gas, this remains a useful relationship. It should be noted that this correlation only seems to be applicable for active carbons. 

To increase rates of adsorption and decrease the time necessary to complete the isotherm, it is recommended that the granular carbon be pulverized so that 95 wt % will pass through a 325-mesh screen. Such pulverization does not significantly increase the surface area. The increase in the surface area, in most cases, is less than 1 percent, as the vast majority of surface area is contributed by the pore walls rather than by the external surface of the carbon particles. 

The Polarizable Continuum Model (PCM) employs a van der Waals surface type cavity, a detailed description of the electrostatic potential, and parameterizes the cavity/ dispersion contributions based on the surface area. The COnductor-like Screening... 

Lu, Vyn, Sandus and Slagg (Ref 17) conducted ignition delay time and initiation studies on solid fuel powder-air mixts in an attempt to determine the feasibility of solid-air detonations. The materials investigated included Al, Mg, Mg-Al alloy, C and PETN. Ignition delay time was used as a method of screening the candidate fuels for further work in initiation studies which determined detonation wave speed, detonation pressure, detonation limits, initiation requirements, and the effect of particle size and confinement. The testing showed the importance of large surface area per unit mass, since the most... 

A small-scale PROX system was manufactured in a type of heat exchanger using non-pellet catalyst. Pt-Ru catalyst screened was impregnated on the support sheet. The support sheet was made by coating y-AlaOs on porous SUS-mesh plate (thickness 1.0 mm). The surface area of the catalyst sheet was 96 mVg. The catalyst sheet was applied to a heat exchanger type reactor of PROX as shown in Fig. 2. The PROX reactor was manufactured as a unit module and tested. Fig. 3 is the test-set of the PROX. Air was applied as the coolant. 

In order to obtain high mass activity of Pt, it is essential to disperse Pt or alloy nanoparticles on high surface area supports. Some questions then arise. What kind of alloys and composition should we choose Is there any good parameter for screening the catalysts What size of catalyst particles should we prepare to obtain the maximum performance Unfortunately, there has been much controversy about such issues in the literature. 

Many inorganic oxides can be manufactured to provide granular, porous materials with high surface areas, which can readily adsorb organic liquids. Preliminary screening of a range of oxides, namely aluminium oxides, titanium dioxides, zinc oxide, hydrotalcites, zeolites and silicas, indicated that the latter two materials were able to retain the largest quantities of biocide. 

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