The critical temperatures and pressures of thirty organic compounds

“…[23] were followed, while for the critical pressure the only known value, i.e., the one reported in Refs. [22,24], was selected for the development of the models. The critical data and other thermodynamic data of interest of diphenyl ether are presented in Table 2.…”

Section: Evaluation Of Available Thermodynamic Datamentioning

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Technical equation of state models for heat transfer fluids made of biphenyl and diphenyl ether and their mixtures

Stelt

Casati

Chan

et al. 2015

Fluid Phase Equilibria

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Estimation of critical properties with group contribution methods

1984

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Currently available group-contribution methods for T,, P,, and V, were evaluated using the Ambrose (1980) critical property data compilation. The Ambrose estimation methods were found to be the most accurate. Linear regression methods were also employed to develop alternate estimation methods which were found to have an accuracy comparable to those of Ambrose.K. M. KLINCEWICZ SCOPECritical properties (T,, P,, V, ) are often required when using generalized property estimation methods. Due to the paucity of experimental values, one must often estimate these properties, and a group-contribution approach is generally used. The method developed by Lydersen (1955) is the most widely employed. However, many new experimental critical properties have become available since the Lydersen report and several alternate estimation schemes have been proposed. In the first portion of this paper, a few methods have been briefly reviewed and evaluated for accuracy using the currently available data.With the rapid advances in linear regression programming, it was felt to be of value to use this methodology to optimize the coefficients and group contributions utilizing a number of objective functions involving T,, P,, or V,. In this manner, one can rapidly test a number of objective functions, selected group-contribution substructures, auxiliary variables, etc. to obtain the least error method of estimation. CONCLUSIONS AND SIGNIFICANCEEvaluating all available estimation methods for T,, P,, and V, , it was shown that the methods of Ambrose (1979Ambrose ( , 1980b were the most accurate. These methods employ Tb/( T, -Tb), (MW/Pc)l12, and V, as objective functions (Q) with the equation forms given in Table 1 and the necessary group contributions in Table 3. The statistics relating to expected errors are shown in Table 5.Linear regression techniques also provided group estimation methods close in accuracy to those of Ambrose but with a simpler set of structural subgroups. In this type of analysis, multicollinearity was identified as a serious problem and the final choice of subgroups minimized the difficulties encountered.The new proposed estimation equations are given as Eqs. 10 through 12 with group contributions in Table 6. Expected errors are shown in Table 7.Models not involving the concept of group contributions were able to explain a large portion of the variance in the critical property data. Reasonably accurate estimation methods could be found where T,, (MW/P,)112, and V, were correlated only with Tb, molecular weight and the number of atoms in the compound. These preliminary results suggest that factor analysis may provide a viable alternate route to group-contributions in the estimation of critical properties.The properties of one material are often related to properties of another by assuming the respective intermolecular potentials of both are similar if the energy and separation variables are scaled appropriately. Materials that behave in this manner are called conformal substances (Rowlinson, 1969). Utilizing relation...

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PRSV: An improved peng—Robinson equation of state for pure compounds and mixtures

1986

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The temperature and acentric factor dependence of the attractive term of the Peng—Robinson equation of state have been modified. The introduction of a single pure compound parameter allows the accurate reproduction of the vapor pressure data for a wide variety of substances. Nonpolar, polar nonassociating and associating compounds are equally well represented by the cubic PRSV equation of state. The conventional one‐binary‐parameter mixing rule allows the correlation of the vapor—liquid equilibrium data for a wide variety of binary systems. Only for systems formed by a polar compound (associating or not) and a saturated hydrocarbon, are results poorer than those obtained with conventional excess Gibbs energy functions.

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The critical temperatures and pressures of thirty organic compounds

Cited by 10 publications

References 27 publications

Technical equation of state models for heat transfer fluids made of biphenyl and diphenyl ether and their mixtures

Technical equation of state models for heat transfer fluids made of biphenyl and diphenyl ether and their mixtures

Estimation of critical properties with group contribution methods

PRSV: An improved peng—Robinson equation of state for pure compounds and mixtures

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