Fluid-phase species

For a continuous fixed bed reactor the pseudo-steady state mass balances for the fluid-phase species A and B are solved numerically with respect to the space time (r) at different times. 

Equation (7-2) states that the observed pollutant solid phase concentration is the result of the competition processes adsorption, desorption and reaction. Furthermore, equation (7-1) establishes that the observed bulk fluid phase species concentration is the result of the difference between the adsoiption and desorption rates. 

Many of the geologically important fluid phase species are molecules which posses permanent dipole moments. Those moments are caused by the asymmetric distribution of electrons about the atomic nuclei. The dipole moments for several molecules are listed in Table 2 where it can be seen that HCl, H2S, NH3, S02r H2O and HF all have significant dipole moments. The potential energy... 

This information allows prediction of X T.E at 323.15 K and at the higher temperatures, 372.8, 397.7, and 422.6 K, for which measured X T.E values are given by Wilsak, et al. (Fluid Phase Equilibria, 28, pp. 13-37 [1986]). Values of In yX and hence of the Margules parameters at the higher temperatures are given by Eq. (4-325) with Cf = 0. The pure-species vapor pressures in all cases are the measured values reported with the data sets. Res lilts of these calculations are displayed in Table 4-1, where the parentheses enclose values from the gamma/ phi approach as reported in the papers cited. 

Another example of phase transitions in two-dimensional systems with purely repulsive interaction is a system of hard discs (of diameter d) with particles of type A and particles of type B in volume V and interaction potential U U ri2) = oo for < 4,51 and zero otherwise, is the distance of two particles, j l, A, B] are their species and = d B = d, AB = d A- A/2). The total number of particles N = N A- Nb and the total volume V is fixed and thus the average density p = p d = Nd /V. Due to the additional repulsion between A and B type particles one can expect a phase separation into an -rich and a 5-rich fluid phase for large values of A > Ac. In a Gibbs ensemble Monte Carlo (GEMC) [192] simulation a system is simulated in two boxes with periodic boundary conditions, particles can be exchanged between the boxes and the volume of both boxes can... 

Fe(CN)6]3-(aq) + 6 H20(1). substrate The chemical species on which an enzyme acts, superconductor An electronic conductor that conducts electricity with zero resistance. See also high-temperature superconductor. supercooled Refers to a liquid cooled to below its freezing point but not yet frozen, supercritical fluid A fluid phase of a substance above its critical temperature and critical pressure. supercritical Having a mass greater than the critical mass. 

Case IV. Irreversible Bimolecular Reactions Between an Adsorbed Species and a Fluid Phase Molecule... 

Hougen- Watson Models for Cases where Adsorption and Desorption Processes are the Rate Limiting Steps. When surface reaction processes are very rapid, the overall conversion rate may be limited by the rate at which adsorption of reactants or desorption of products takes place. Usually only one of the many species in a reaction mixture will not be in adsorptive equilibrium. This generalization will be taken as a basis for developing the expressions for overall conversion rates that apply when adsorption or desorption processes are rate limiting. In this treatment we will assume that chemical reaction equilibrium exists between various adsorbed species on the catalyst surface, even though reaction equilibrium will not prevail in the fluid phase. 

Qads.(max) = 5.7 molecules by unit cell). Generally speaking, Qacis.(max) is closely related to the molecular size, as it is observed for the other molecular species. Secondly, as shown on Figure 5, sorption isotherm sub-step observation could be another signature of zeolite inner surface influence. Such isotherm sub-step reflects a phase transition existence between a fluid phase and a solid phase stabilized by the inner surface sorption sites. 

Advances continue in the treatment of detonation mixtures that include explicit polar and ionic contributions. The new formalism places on a solid footing the modeling of polar species, opens the possibility of realistic multiple fluid phase chemical equilibrium calculations (polar—nonpolar phase segregation), extends the validity domain of the EXP6 library,40 and opens the possibility of applications in a wider regime of pressures and temperatures. 

Under the simulation conditions, the HMX was found to exist in a highly reactive dense fluid. Important differences exist between the dense fluid (supercritical) phase and the solid phase, which is stable at standard conditions. One difference is that the dense fluid phase cannot accommodate long-lived voids, bubbles, or other static defects, whereas voids, bubbles, and defects are known to be important in initiating the chemistry of solid explosives.107 On the contrary, numerous fluctuations in the local environment occur within a time scale of tens of femtoseconds (fs) in the dense fluid phase. The fast reactivity of the dense fluid phase and the short spatial coherence length make it well suited for molecular dynamics study with a finite system for a limited period of time chemical reactions occurred within 50 fs under the simulation conditions. Stable molecular species such as H20, N2, C02, and CO were formed in less than 1 ps. 

The equilibrium diagram (2, p. 274 6) for the species in Equation (13.16) is shown in Figure 13.7. If gypsum and anhydrite are both under liquid water at 1 bar, then equUibrium can be attained only at 40°C (see Fig. 13.7). If the hquid pressure is increased, and the rock formation is completely impermeable to the hquid phase, so that the pressure on the fluid phase is equal to the pressure on the sohd phase, then the temperature at which the two solids, both subject to this hquid pressure, are in equUibrium is given by the curve with positive slope on the right side of Figure 13.7. Thus, the right curve apphes to any situation in which Pp is equal to Ps- Under these conditions, the net AV , for the transformation of Equation (13.16) is 36.14 29.48 = 6.66 cm [see Equations (13.18) and (13.19)],... 

We emphasize that we are interested in the fluid-phase diffusion coefficient of the reactant A, which we call D, and also the solid-phase diffusion of this species D,4s (bold and subscript s). The diffusion of reactant A in either situation can limit the reaction process. 

In Eq. 1, y is the free interfacial enthalpy per surface unit, Sg is the total surface of the interface, N is the number of monomeric entities changing from the solution state (1) to the condensed state (2) /xi and /X2 are the chemical potentials of the monomeric species in the initial fluid phase and in the condensed phase that is constituted thereafter. 

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