An accurate method for testing the thermodynamic consistency of isothermal binary vapour—liquid equilibrium data

✍ Scribed by R. Techo

• Publisher: Elsevier Science
• Year: 1963
• Tongue: English
• Weight: 583 KB
• Volume: 18
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(63)80002-0

✦ Synopsis

This paper presents a method for using electronic digital computers to determine the thermodynamic consistency of isothermal binary vapour-liquid equilibrium data. Two sets of orthogonal polynomials, P = P(x) and y = y(x), are obtained by fitting the experimental total pressure and vapour-composition data as functions of the liquid composition according to the method of least squares. For P(x) and y(x) various polynomials ranging in degree from 2 to the number of experimental data points less one are determined. All the combinations of the degrees of the fitted polynomals are used to compute the excess chemical potentials which are substituted into the Gibbs-Duhem equation. That combination of polynomials, P = P(x) and y = v(x), which minimizes the Gibbs-Duhem equation is then said to characterize the experimental data in the best possible manner with regard to thermodynamic consistency. Criteria are given for determining whether or not data are thermodynamically consistent. The procedure is developed and an example is presented.