Sweep factor, defined

Both theoretical and experimental studies have been performed on palladium-based membrane reactors for the water-gas shift reaction. Ma and Lund simulated the performance achievable in a high temperature water-gas shift membrane reactor using both ideal membranes and catalysts [18]. By comparing the results obtained with those related to the existing palladium membrane reactors, they concluded that better membrane materials are not needed, and that higher performances mainly depend on the development of a water-gas shift catalyst not inhibited by CO2. Marigliano et al. pointed out how the equilibrium shift conversion in membrane reactors is an increasing function of the sweep factor (defined as the ratio between the flow rate of the sweep at the permeate side and the flow rate of CO at the reaction side) [19]. The ratio is an index of the extractive capacity of the system. 

M REC, as the TREC, does not depend on the reaction path. In addition, there is no dependence on the membrane-permeation properties (related to the time required for species permeation).1 In any case, the final value reached depends on the extractive capacity of the system, for example, the pressure and composition on the permeate side. The composition on the permeate side, similarly to the feed molar ratio, can be expressed by considering the ratio (named sweep factor) between the initial molar number of nonpermeating species (present on the permeate side) and the initial molar number of the reference reactant, for example, methane for methane steam reforming, or carbon monoxide for water gas shift). The sweep factor was defined for a closed M Ras ... 

The sweep factor can be defined in analogous way for an open MR such as a plug-flow, in this case flow rates of feed and sweep streams are used instead of the number of moles ... 

Marigliano et al. performed further modelling work for methane steam reforming and water-gas shift in membrane reactors [415]. They defined the sweep factor I as the ratio of flow rates of inert gas on the permeate side to the flow rate of methane on the reaction side of the membrane ... 

Another point is that the reduction and oxidation potential limits (electrochemical window) are defined as the potentials at which the current density reaches a predefined value that is arbitrarily chosen [40, 48], Ue et al. also mention that the same problem arises in the choice of the sweep rate [40]. For example Egashira and coworkers obtained a log I- U line shifted to a higher position at a faster potential scan in comparison to a slower scan because of non-Faradaic currents such as the larger charging currents of the double-layer, and the decomposition of impurities [41]. The last factor affecting the electrochemical window is the electrode itself, its composition and its morphological surface structure, which defines the electrocatalytic properties [40]. 

There is yet another expansion factor we can define, the I/O expansion factor, which we take as the ratio of the outlet flow rate to the inlet flow rate, allowing for the expansion in total flow. From the discussion preceding equation 5.59 we see that the outlet flow rate, allowing for thermal expansion as well as desorption is (Toa/T fo + kmVjT, while the expanded flow of sweeping gas alone at the outlet will be (Toa/Tj,). Hence the I/O expansion feet or is... 

Adiabatic pulses are described by their frequency sweep and amplitude profile, which, when combined with the peak rf amplitude cc max), defines the total power of the pulse. The total frequency range, AF, over which the pulse sweeps is commonly many tens of kilohertz and pulse durations, T, are typically of the order of 1 ms, corresponding to frequency sweep rates of 10-100 MHz/s. The degree to which the adiabatic condition is satisfied for the pulse is quantified by the adiabaticity factor Q... 

A macroscopic thermodynamic understanding of the preexponential factor was greatly advanced by the work of Kohnstamm and Scheffer [5], who introduced the concept of the Gibbs free energy of activation. A complementary molecular understanding came from the collision theory approach of McC Lewis [6], which is rather remarkable for its simplicity. If a collision between molecules A and B is defined as the two molecules coming within (rA-hrs), the sum of the radii, then each molecule of A with relative velocity vab will sweep out a cylinder of length vab Z and cross section n rp -h re). The mean relative velocity, vab, had been calculated 50 years earlier by Maxwell and Boltzmann [7] ... 

A series of changes takes place in the nucleic acid metabolism of the remnant, some of which are evident within an hour after surgery. A well-defined wave of DNA synthesis sweeps through the tissue 18-24 hours after surgery this event coincides roughly with a burst of mitotic activity. Some synchronization of cell metabolic activities is indicated by the time course of these events however, the synchrony is soon lost. Definition of the biochemical factors which initiate the sudden burst of DNA synthesis has been a particular goal of investigators. 

There are two important points to make for the interpretation of this returning sweep in the CV. First, this sweep is an analysis of the contents of solution close to the electrode surface at a specific time. Consider the quantitative analysis of the intensity of the first reoxidation peak encountered at -0.05 V. The duration of time between the copper s reduction at -0.15 V and its oxidation at -0.05 V is defined by the scan rate. Based on a scan rate of 0.2 V s the CV takes 4.5 s to traverse a total of 0.9 V during the end of the forward sweep and the beginning of the reverse sweep. Thus, the peak intensity at —0.05 V is a measurement of the system after 4.5 s. The second important factor to consider is the effect of diffusion on the CV peak intensities. 

Despite the fact that the Nernst model is rather rough, it has been used in electrochemical kinetics up till now due to its simplicity and obviousness. It has been established by means of different methods that similar structures actually form in the conditions of natural convection. Their thickness makes up 0.01-0.03 cm however, it is rather difficult to strictly define because it depends on various factors, including the current density i. The empirical regularity const has been established experimentally under the steady-state conditions [1]. It should be mentioned that varies with the potential sweep rate v when a linear variation... 

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