Corresponding-state correlation

Pitzer s Corresponding-States Correlation A three-parameter corresponding-states correlation of the type developed by Pitzer, K.S. Thennodynamic.s, 3ded., App. 3, McGraw-HiU, New York, 1995) is described in Sec. 2. It has as its basis an equation for the compressibility factor ... 

Corresponding-states correlations for pure components rest upon several fundamental assumptions which are discussed elsewhere (G3, H4, H6). To extend such correlations to mixtures, it is necessary to make an additional fundamental assumption, viz, that the characterizing parameters chosen (TcMr FCm, and (oM) are independent of temperature and density and are... 

Several authors, notably Leland and co-workers (L2), have discussed vapor-liquid equilibrium calculations based on corresponding-states correlations. As mentioned in Section II, such calculations rest not only on the general assumptions of corresponding-states theory, but also on the additional assumption that the characterizing parameters for a mixture do not depend on temperature or density but are functions of composition only. Further, it is necessary clearly to specify these functions (commonly known as mixing rules), and experience has shown that if good results are to be obtained, these... 

Plocker, U., Knapp, H. and Prausnitz, J. (1978) Ind. Eng. Chem. Proc. Des. and Dev. 17, 243. Calculation of high-pressure vapour-liquid equilibria from a corresponding-states correlation with emphasis... 

Finally, let us look at the corresponding state correlation diagram, as shown in Figure 7.18. In constructing this, we use the direct product rules ... 

High-Pressure Vapor-Liquid Equilibria from a Corresponding States Correlation with Emphasis on Asymmetric Mixtures," I EC Process Design and Development, 1978, 17, 324. 

The perturbation theories [2, 3] go a step beyond corresponding states the properties (e.g., Ac) of some substance with potential U are related to those for a simpler reference substance with potential Uq by a perturbation expansion (Ac = Aq + A + Aj + ). The properties of the simple reference fluid can be obtained from experimental data (or from simulation data for model fluids such as hard spheres) or corresponding states correlations, while the perturbation corrections are calculated from the statistical mechanical expressions, which involve only reference fluid properties and the perturbing potential. Cluster expansions involve a series in molecular clusters and are closely related to the perturbation theories they have proved particularly useful for moderately dense gases, dilute solutions, hydrogen-bonded liquids, and ionic solutions. 

Figures 3.12 and 3.13 for Z°, based on data for the simple fluids, provide a complete two- parameter corresponding-states correlation for Z Since the second term of Eq. (3.45) is a relatively small correction to this two-parameter correlation, its omission does not introduce large errors. Thus Figs. 3.12 and 3.13 may be used alone for quick but less precise estimates of Z than are obtained from the complete three-parameter correlation.

If we take Z = Z° = 0.865, in accord with the two-parameter corresponding states correlation, then V = 1,467.1 cm,mor1, which is less than 1 percent lower than the value given by the three-parameter correlation. 

Figures 6.6, 6.7, 6.10, and 6.11 for (HRf/RTc and (SR)°/R, used alon provide two-parameter corresponding-states correlations that quickly yield coars estimates of the residual properties.

Clausius/Clapeyron equation, 182 Coefficient of performance, 275-279, 282-283 Combustion, standard heat of, 123 Compressibility, isothermal, 58-59, 171-172 Compressibility factor, 62-63, 176 generalized correlations for, 85-96 for mixtures, 471-472, 476-477 Compression, in flow processes, 234-241 Conservation of energy, 12-17, 212-217 (See also First law of thermodynamics) Consistency, of VLE data, 355-357 Continuity equation, 211 Control volume, 210-211, 548-550 Conversion factors, table of, 570 Corresponding states correlations, 87-92, 189-199, 334-343 theorem of, 86... 

Related Calculations. This illustration outlines various simple techniques for estimating P-V-T properties of gaseous mixtures. Obtain the compressibility factor from the generalized corresponding-state correlation, as shown in step 2. 

Estimate the saturated-liquid heat capacity of (a) n-octane and (b) ethyl mercaptan at 27°C (80.6°F) using the Yuan-Stiel corresponding-states correlation [19], given as... 

Estimate the surface tension, a, of n-butane at 20°C using the generalized corresponding state correlation of Brock and Bird [32] and the Miller relationship [33], The correlation and the relationship are as follows ... 

Critical temperature - useful in corresponding state correlations for thermodynamic and transport properties... 

Critical volume - helpful in corresponding state correlations... 

Lydersen, Greeirkonr, aird Hougeii developed a two-parairreter corresponding-states correlation for estimatioir of liquid vohurres. It provides a correlatioir of reduced density as afuirction of reduced teirrperature aird pressure. By defiirition. 

Recommended Method 2 Corresponding states correlation. Reference PGL5, p. 7.18. 

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