Interpretation of overall area tests for thermodynamic consistency: The effect of random error

Abstract

Methods are developed and illustrated for determining the amount of nonsatisfaction of the overall area (integrated Gibbs‐Duhem equation) test for vapor‐liquid equilibrium data that is to be expected on the basis of random experimental uncertainties. Data which satisfy the overall test within these limits, as well as the local area test, are said to be consistent within the bounds established by their experimental uncertainties, while data which do not are said to show significant systematic error and hence are termed inconsistent.

Vapor−Liquid Equilibria in the 2-Methylcyclohexanol + 2-Methylcyclohexyl Ethanoate System at 101.325 kPa

“…Two point-to-point tests were used, that proposed by Mc-Dermott and Ellis and further modified by Wisniak and Tamir 12 and that of Samuels and Ulrichson. 13 Our data passed both above tests. In calculations uncertainties in all the measurables were used as reported above with value for vapor phase as modified after the MML calculations.…”

“…Two point-to-point tests were used, that proposed by McDermott and Ellis and further modified by Wisniak and Tamir and that of Samuels and Ulrichson . Our data passed both above tests.…”

Measurement and prediction of high‐pressure phase equilibria with a dilute component in the gas phase: The methane‐n‐hexane system

“…Several authors (Chueh et al, 1965;Thompson and Edmister, 1965;Adler et a]., 1960;Won and Prausnitz, 1973;Samuels et al, 1972) have described thermodynamic consistency tests for experimental data at moderate pressures. For isothermal measurements the general relationship for an integral test of an N component mixture is…”

Method of evaluation and reduction of vapor‐liquid equilibrium data of binary mixtures

“…Evaluation of experimental data has been made traditionally by tests of consistency. However, recent papers have questioned the former use of the area test; Van Ness et al (1973) recommend concentration of efforts in improving measurements rather than obtaining redundant data for such tests; Samuels et al (1972) and Ulrichson and Stevenson (1972) redirect the attention towards the effect of random errors, incorporating the experimental evaluation of these errors into the use of a test.…”