Thermodynamic and statistical consistency of vapor–liquid equilibrium data

The validation of vapor–liquid equilibrium (VLE) data sets using point to point or area tests is not a sufficient condition for their consistency. It is also necessary to analyze the statistical consistency of the activity coefficient model that represents the VLE data. In this work it is shown how to test both consistencies applying statistical tests to the residuals (differences between experimental and calculated values) of the variables related with the VLE data fit. Results from the application to four different VLE data sets shows that thermodynamic consistency and statistical consistency are not necessarily related, making necessary to apply both the area test and the analysis of residuals, for all variables.