Corresponding composition scales

A particularly useful concept in synthesizing MENs is the notion of corresponding composition scales. It is a tool for incorporating thennodynamic constraints... 

Equation (3.5) can be used to establish a one-to-one correspondence among all composition scales for which mass exchange is feasible. Since most environmental applications involve dilute systems, one can assume that these systems behave ideally. Hence, the transfer of the pollutant is indifferent to the existence of other species in the waste stream. In other words, even if two waste streams contain species that are not identical, but share the same composition of a particular pollutant, the equilibrium composition of the pollutant in an MSA will be the same for both waste streams. Hence, a single composition scale, y, can be used to represent the concentration of the pollutant in any waste stream. Next, (3.5) can be employed to generate Ns scales for the MSAs. For a given set of corresponding composition scales y,x, X2,..., xj,..., it is thermodynamically and practically feasible to transfer the pollutant from any waste stream to any MSA. In addition, it is also feasible to transfer the pollutant from any waste stream of a composition y/ to any MSA which has a composition less than the xy obtained from (3.5b). 

The CID is a useful tool for insuring diermodynamic feasibility of mass exchange. On this dia am, N,p + 1 corresponding composition scales are generated. First, a composition scale, y, for the waste streams is established. Then, Eq, (3.5) is employed to create Nsp corresponding composition scales for the process MSAs. On the CID, each process stream is represented as a vertical arrow whose tail corresponds to its supply composition while its head represents its target composition. Next, horizontal lines are drawn at the heads and tails of the arrows. These horizontal lines define a series of composition intervals. The number of intervals... 

Corresponding composition scales for reactive mass exchange... 

Corresponding Composition Scales for Reactive IVfass Exchange... 

Now that a procedure for establishing the corresponding composition scales for the rich lean pairs of stream has been outlined, it is possible to develop the CID. The CID is ccHistructed in a manner similar to that described in Chapter Five. However, it should be noted that the conversion among the corresponding composition scales may be more laborious due to the nonlinearity of equilibrium relations. Furthermore, a lean scale, xj, represents all forms (physically dissolved and chemically combined) of the pollutant. First, a composition scale, y, for component A in... 

This value corresponds to a corresponding y-scale composition of 0.0012, which is less than the supply mass fmction of phenol in either waste stream as well as the pinch composition. Hence, it is thermodynamically feasible for Sf to recover phenol from R] and R2. In addition, miy amount of phenol removed by S5 does not overlap with the load handled by the process MSAs. Therefore, the operating cost of air needed to remove 1 kg of phenol can be evaluated as follows ... 

In addition, by scaling the filler size to the nanometer scale, it has been shown that novel material properties can be obtained. Nanoscaled fillers are those having at least one dimension in the range of nanometers (< 100 nm) [3]. When the dimensions of the reinforcement approach the nanometer scale, a number of effects make the properties of the corresponding composites different from those of composites reinforced with micro-scaled fillers. The major influencing factors of the properties of nanocomposites are nanofiller dispersion, dimensions, volume fractions, nature of the matrix material, interfacial properties between filler and matrix, and manufacturing process [4]. 

In the preceding discussion on oxidation of composites, each matrix phase reacted with oxygen to form its corresponding oxide. No interactions between matrix or oxide phases were reported. In this section, a few examples are discussed in which the composite scale contains oxide compounds formed from more than one component of the matrix phases, e.g. mullite, zircon, or aluminum borates. This is not intended to be a complete review, but an illustration of the kinds of effects compound formation can have on oxidation behavior. For example, formation of the compound oxide scales may result in higher oxidation rates if the compound oxide is more permeable to oxygen, or likewise, lower oxidation rates if the compound oxide is less oxygen permeable. The volatility of scale components can also be reduced by the formation of compound oxides as will be discussed below for aluminum borates. 

This fomi is called a Ginzburg-Landau expansion. The first temi f(m) corresponds to the free energy of a homogeneous (bulk-like) system and detemiines the phase behaviour. For t> 0 the fiinction/exliibits two minima at = 37. This value corresponds to the composition difference of the two coexisting phases. The second contribution specifies the cost of an inhomogeneous order parameter profile. / sets the typical length scale. 

Interpreting results of the pinch diagram As can be seen from Fig. 3.12, the pinch is located at the corresponding mole fractions (y,Xi.jc ) - (0.(K)10, 0.0030, 0.0010). The excess capacity of the process MSAs is 1.4 x lO" kg mol benzene/s and cannot be used because of thermodynamic and practical-feasibility limitations. This excess can be eliminated by reducing the outlet compositions and/or flowrates of the process MSAs. Since the inlet composition of S2 corresponds to a mole fraction of 0.0015 on the y scale, the waste load immediately... 

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