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Saturated liquid densities for binary hydrocarbon systems
Author(s) -
Phillips Edward M.,
Thodos George
Publication year - 1961
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690070314
Subject(s) - heptane , butane , thermodynamics , hydrocarbon , binary number , vapor–liquid equilibrium , work (physics) , cyclohexane , hydrocarbon mixtures , chemistry , alkane , binary system , reduced properties , organic chemistry , mathematics , physics , arithmetic , catalysis
The extension of the rules proposed by Cailletet and Mathias for the sum of the saturated vapor and liquid densities and by Guggenheim for the difference of these densities enabled the development of a method for the prediction of liquid densities for binary hydrocarbon systems at saturated conditions. The theorem by corresponding states indicated that unique relationships should exist between the reduced temperature and the sum and difference of the reduced saturated liquid density and the reduced saturated vapor density. Density data reported by Kay for the systems n ‐butane— n ‐heptane, ethane— n ‐butane, ethane— n ‐heptane, and ethane—cyclohexane were used to determine the exponents and the coefficients of the resulting equations. The exponents were found to be functions of two temperature parameters, which take into account both the components and composition of the mixture, while their coefficients have been found to depend only on their exponents. It has been previously shown that critical temperatures of binary hydrocarbon systems can be predicted with the two temperature parameters. In this study it has been found that these two parameters can also be applied to determine the critical densities for these binary hydrocarbon systems. Using these critical properties one can directly obtain the saturated liquid densities of binary systems from the two reduced‐density relationship. The method developed in this work reproduces the saturated liquid densities of the four systems within 4.8%. In addition saturated densities have been calculated for the ethylene— n ‐heptane system and checked the experimental values within 3.2%. Because saturated vapor densities are small compared with the saturated liquid densities for conditions removed from the critical point, the sum and difference of the liquid and vapor densities are approximately the same. Thus this method cannot be used with any reliability to determine the densities of saturated vapors. At present this method can be applied only to hydrocarbon mixtures whose atmospheric dew point does not exceed twice its atmospheric boiling point.