Speed enhancement factor

In an effort to quantitate the increase in GCMS analysis speed, one author has suggested the descriptors fast, very fast, and ulfrafast (154). These are based on the definition of the new term, speed enhancement factor (SEF), which is defined as the product of column length reduction and the increase in carrier-gas Unear velocity for the chromatographic separation. Using this description, SEFs of 5-30, 30-400, and 400-4000 correspond to fast, very fast, and ultrafast. 

We show in Figs. 2 and 3 the speed up for a Davidson iteration obtained with the PVM [17] ( Parallel Virtual Machine ) and PVMe [18] ( PVM enhanced ) message passing interfaces respectively. Speed-up factors are here relative to the sequential version of the program (n=l), and the theoretical mciximum has been defined according to the expression s n) — n — I appropriate to the used master/slave model. 

Zlokarnik [623] made use of this possibility in his investigations. They consisted of measuring kia values by means of manometric method, see Section 4.3.1.2 and Fig. 4.2, at constant stirrer speed for a large number of aqueous solutions of inorganic salts and acids with different concentrations in the absorption of pure nitrogen. They were represented in the form of the enhancement factor m (qt physical absorption ... 

For a given gas-liquid system, the gas side should either be pure or used at a very high flow rate so that issues related to gas-phase back-mixing are eliminated. Furthermore, the gas-phase impeller speed is varied such that, beyond a particnlar impeller speed, the rate becomes independent of speed, ensnring that the gas-phase resistance is eliminated. For a given gas-liquid system, the specihc rate of absorption, 7 , is measnred, and the enhancement factor is estimated nsing the following equation ... 

Design a two-phase gas-liquid CSTR that operates at 55°C to accomplish the liquid-phase chlorination of benzene. Benzene enters as a liquid, possibly diluted by an inert solvent, and chlorine gas is bubbled through the liquid mixture. It is only necessary to consider the first chlorination reaction because the kinetic rate constant for the second reaction is a factor of 8 smaller than the kinetic rate constant for the first reaction at 55°C. Furthermore, the kinetic rate constant for the third reaction is a factor of 243 smaller than the kinetic rate constant for the first reaction at 55°C. The extents of reaction for the second and third chlorination steps ( 2 and 3) are much smaller than the value of for any simulation (i.e., see Section 1-2.2). Chlorine gas must diffuse across the gas-liquid interface before the reaction can occur. The total gas-phase volume within the CSTR depends directly on the inlet flow rate ratio of gaseous chlorine to hquid benzene, and the impeller speed-gas sparger combination produces gas bubbles that are 2 mm in diameter. Hence, interphase mass transfer must be considered via mass transfer coefficients. The chemical reaction occurs predominantly in the liquid phase. In this respect, it is necessary to introduce a chemical reaction enhancement factor to correct liquid-phase mass transfer coefficients, as given by equation (13-18). This is accomplished via the dimensionless correlation for one-dimensional diffusion and pseudo-first-order irreversible chemical reaction ... 

From the viewpoint of comparing such models with the observations of Oph, the fall in N(CH) between (a) and (b) is to be welcomed, but the rise in Tjj and its consequences are undesirable. However, as general conclusions should not be based on the results of a single model, we have attempted to tune the parameters of the shock, particularly the shock speed Ug and the radiation enhancement factor X, to optimise the level of agreement with the observations of C Oph. The preliminary results of this optimisation procedure are compared with the observed column densities in Table 4. 

In this chapter, a fast reaction is one whose chemical kinetics is the same speed or faster than diffusion, but one where the reagents can coexist. In this case, the actual rate is a function both of diffusion coefficients and of reaction rate constants, as detailed in Section 17.1. This interaction leads both to the enhancement factors used in reactive gas treating and to the effectiveness factors important for porous catalysts. 

N = impeller speed Breakage occurs when N > Nc,-Maximum enhancement before breakage was factor of 2.0. 

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