Compression kinetics

All minerals subjected to the shear strength measurement have been compressed for half an hour at varying pressures to obtain a stable cake height. This compression time (half an hour) has been chosen according to the typical compression kinetics of Ti02 as an example given in Fig.2. As it is seen in Fig.2, the cakes have reached to a constant height in 3-5 minutes by compression at 4-20 bar and therefore to make sure 30 minutes has been taken as the compression time in each experiment. 

Figure 2. Compression kinetics of TiO pressure filter cakes at different pressures.

Schroeder J 1997 Picosecond kinetics of trans-cis photoisomerisations from ]et-cooled molecules to compressed solutions Ber. Bunsenges Phys. Chem. 101 643... 

Compressible Vlow. The flow of easily compressible fluids, ie, gases, exhibits features not evident in the flow of substantially incompressible fluid, ie, Hquids. These differences arise because of the ease with which gas velocities can be brought to or beyond the speed of sound and the substantial reversible exchange possible between kinetic energy and internal energy. The Mach number, the ratio of the gas velocity to the local speed of sound, plays a central role in describing such flows. 

A crystalline or semicrystalline state in polymers can be induced by thermal changes from a melt or from a glass, by strain, by organic vapors, or by Hquid solvents (40). Polymer crystallization can also be induced by compressed (or supercritical) gases, such as CO2 (41). The plasticization of a polymer by CO2 can increase the polymer segmental motions so that crystallization is kinetically possible. Because the amount of gas (or fluid) sorbed into the polymer is a dkect function of the pressure, the rate and extent of crystallization may be controUed by controlling the supercritical fluid pressure. As a result of this abiHty to induce crystallization, a history effect may be introduced into polymers. This can be an important consideration for polymer processing and gas permeation membranes. 

Other volume-explicit equations of state are sometimes required, such as the compressibility equation V = zRT/P or the truncated virial equation V= (1 -i- B P)RT/P. The quantities z a.ndB are not constants, so some land of averaging will be required. More accurate equations of state are even more difficult to use but are not often justified for kinetic work. 

For the reaction KCIO4 -t- 2C KCl -t- CO2, fine powders were compressed to 69 MPa (10,000 psi) and reacted at 350°C (662°F), well Below the 500°C (932°F) melting point. The kinetic data were fitted by the equation... 

Blast Peening—a treatment for relieving tensile stress via inducing beneficial compressive stress in the surface by kinetic energy of rounded abrasive particles. 

Melting, a major physical event, has small, subtle effects on shock-compression wave profiles. The relatively small volume changes and limited mixed-phase regions result in modest, localized changes in loading wave speed. Consequently, shock-induced melting and freezing remains an area with little data and virtually no information on the influence of solid properties and defects on its kinetics. 

An inventor claims to have devised a CO. compressor that requires no shaft work. The device operates at steady state by transferring heat from a feed stream of 2 lb,/s of CO. at 150 psia and 100°F. The CO is compressed to a final pressure of 500 psia and a temperature of 40°F. Kinetic and potential energy effects are negligible. A cold source at -140°F drives the device at a heat transfer rate of 60 Btu/sec. Check the validity of the inventor s claim. 

An elementary solid, such as silver, is regarded as composed of atoms oscillating about fixed centres. The total energy content is therefore partly kinetic and partly potential. Since the solid has a finite compressibility, the atoms may be supposed to be maintained at small distances apart by forces they exert upon one another, and these may be resolved into two sets, one of which opposes a closer approximation of the atoms, and the other tends to draw the latter together. Both are functions of the distance between the atoms, and for a given distance are equal, since the form of the body is altered by external forces alone. 

Since stab detonators contain no restraining anvil as do percussion primers, the resistance to penetration of the firing pin becomes quite im-. portant. This is the role of compression or density of the mixt. With higher density, the kinetic energy of the firing pin is dissipated over... 

Compression of powder samples into pellets can also influence the kinetics of decomposition [97,391—393], mainly through hindering the escape of reaction products. 

The power requirement is then that for compression of the gas from pressure Pi to P3 and for imparting the necessary kinetic energy to it. Under normal conditions, however, the kinetic energy term is negligible. Thus for an isothermal efficiency of compression 17. the power required is ... 

Fig. 1.16. Angular momentum and kinetic energy correlation functions for compressed nitrogen. MD simulation from [62], T = 300 K. The lines are continuous (800 amagat), close dotted (600 amagat), sparse dotted (400 amagat), dashed (300 amagat) and pairwise dotted (200 amagat). Reduced time units are the same as in Fig. 1.15.

Two types of observations show that our model of a gas must be refined. The qualitative observation is that gases can be condensed to liquids when cooled or compressed. This property strongly suggests that, contrary to the assumptions of the kinetic model, gas molecules do attract one another because otherwise they would not cohere (stick together). In addition, liquids are very difficult to compress. This... 

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