Critical Evaluation of Vapor-Liquid Equilibrium, Heat of Mixing, and Volume Change of Mixing Data. General Procedures

Abstract

This paper is the first in a series of reports on the critical evaluation of vapor-liquid equilibrium, heat of mixing, and volume change of mixing data for binary liquid mixtures of nonelectrolytes. The specific evaluation procedures for each property will be covered in subsequent articles. This paper describes the general procedures used to support the mixture evaluation work. The areas covered include the procedures used to cover the primary and secondary literature, the computer program libraries developed for pure compound and mixture data processing, the procedures used to evaluate and correlate the pure compound property data for use by the mixture programs, and the efforts made to make the best equation of state available to the vapor-liquid equilibrium data reduction programs. Improvements are suggested for the presentation of mixture data in the literature.

Evaluation of Binary PTxy Vapor–Liquid Equilibrium Data for C6 Hydrocarbons. Benzene+Cyclohexane

“…Each of these lead papers presents the specific evaluation methods used for the given property and then applies those methods to the first binary system to be covered-the benzene-(1) + cyclohexane(2) system. These lead papers have been preceded by another paper [3] which described those Laboratory procedures that are not specific to one of the three mixture properties being covered. Items covered there include the literature document retrieval methods, the computer program libraries developed for the pure compound and mixture evaluation projects, the methud~ used to evaluate pure compound data and store it in a computer where it is readily ~vailable to the mixture programs, and the way equations of state are used to model the vapor-phase behavior inthe VLE data sets evaluated.…”

“…The benzene + cyclohexane should be a good candidate for a test system for both P, T, x,y and P, T, x VLE devices. It is hoped that this paper will be useful in the evaluation of the benzene-y.p~.p (2) (3) which appears in approximate form in eq 1 represents the effect of pressure on the fugacity of the pure liquid i. It involves the pure liquid volume V~ which must always be an hypothetical quantity for the more volatile component in a binary liquid mixture.…”

“…It is always as~umed that those fugacity coefficienis·can-be predicted with suffiCient-accuracy by -an assumed equation of state. The equations of state available to the data reduction program, and the logic used to select the best possible equation of state for a given mixture, are described in a previous paper [3].…”

Evaluation of Binary Excess Volume Data for C6 Hydrocarbons. Benzene+Cyclohexane

“…If not reported, the computer program VECON which converts the mixture or density data to VB values accesses the pure compound data bank CDATAI for the needed pure compound values. The general procedures used in selecting and correlating the pure compound liquid density data and storing it in CDAT Al have been described in the preceding paper [3].…”

“…ed-the benzene( 1) + cyclohexane(2) system. These three papers have been precede:il hy ~:mother paper [3] which described those Laboratory procedures which are not specific to one of the three mixture properties being covered. Items covered there include the literature document retrieval methods, the computer program libraries developed for the pure compound and mixture evaluation projects, the methods used to evaluate pure compound data and store it in a computer data bank in order to make good compound data readily available to the mixture programs, and the way equatiolls-of-state are used to model the vaporphase behavior in the VLE data sets evaluated.…”