Quality Assessment Algorithm for Vapor−Liquid Equilibrium Data

The Rossini lecture affords the lecturer an opportunity to review his contributions to a subject and to reflect on them from the perspective of an extended career. The subject here is vapor/liquid equilibrium, and the topics reviewed include property relations, experimental measurements, consistency tests, and data reduction and correlation.

AIChE Journal, 2019

In this work, a method is proposed to validate the experimental data of solutions of ncomponents in vapor-liquid equilibria (VLE) with some non-volatile component (nv-VLE). The methodology is based on the resolution of the differential Gibbs-Duhem equation using two forms (differential and integral) described in a previous work. The i , ψ ε is determined by an uncertainty This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as

AIChE Journal, 1997

A method for testing the thermodynamic consistency of binaiy and isothemal vapor-liquid equilibrium data at moderate and high pressures is proposed, using a 9-4p approach. The Redlich-Kwong-Soave equation of state with Huron-Kdal mixing rules at infinite pressure is used in the data-reduction procedure, and a Margules equation is used to calculate the activity coeficients at infinite pressure. This model is shown to be thermodynamically consistent. The proposed method allows us to check consistency of vapor-liquid equilibrium data in the presence of components at the gaseous and supercritical states.

international journal of chemical sciences, 2016

In the present study, vapor liquid equilibrium data (VLE) has been generated for binary system: acetic acid and p-xylene, at atmospheric pressure (96.15 Kpa). The recirculation type of apparatus was used for generating the VLE data for a given temperature and compositions1. The activity coefficients were estimated using Wilson and NRTL models at different composition. It has been seen that experimental data fits well to the predicted data. Further, thermodynamic consistency of experimental data has been confirmed using Redlich- Kister and point to point test methods. It has been found that experimental data is thermodynamically consistent.

Industrial & Engineering Chemistry Research, 1993

A new thermodynamic consistency test of vapor-liquid equilibrium data a t low pressure has been proposed based on the equation that describes the bubble point of the mixture. The test can be used in a point-to-point or area manner and requires knowledge or estimation of the heat of vaporization of the pure components. The point-to-point mode is applicable to binary and multicomponent data and simplifies the locating of experimental errors.

Industrial & Engineering Chemistry Research, 1993

Optimal binary interaction coefficients have been determined for a generalized equation of state for associating mixtures using a large data base of 170 binary systems compiled from the literature. The data base covers gases (H2, N2, CO, C02, and H2S), hydrocarbons, alcohols, and water. Results show substantial improvements in accuracy for the equation of state presented here relative to the Soave equation. Average errors in estimated bubble point pressure ranged from 2.1 % to 8.7 % for CHI, H2S, N2, CO, C02, H2, H20, MeOH, and EtOH systems when optimal binary interaction coefficients were used. The accuracy for the gaseous components is roughly equivalent to that of the Soave equation, but for water, methanol, and ethanol systems, the optimized Soave equation provides 20 % , 1 5 % , and 10 % error. For systems without optimal binary interaction coefficients, predictive methods were developed. For predictions treating nongaseous components, errors in estimated bubble point pressure ranged from 0.7 % to 8.1 % when this method was applied. For predictions treating gaseous components, errors in estimated bubble point pressure ranged from 5.0 7% to 37.6% for CH4, HzS, N2, CO, C02, and H2 when the predicted interaction coefficients were applied. Tables of optimal binary interaction coefficients where available and estimated interaction coefficients where necessary are presented for roughly 350 binary systems over a wide range of temperatures and pressures.

Ind. Eng. Chem. Res

A new data treatment approach for ternary systems is presented. The method is a model-free technique based on Barker's equation and integration of the Gibbs−Duhem relation. It yields numerical information for the excess ...

AIChE Journal, 1960

Methods are developed for testing binary system phase-equilibrium doto for thermodynamic consistency when the more volatile component is above its critical temperature. The isothermal case with varying pressure and the isobaric cose with varying temperature are considered indmdually. The rigorous form of the Duhem equation is employed rather than the simplified one, which for binary systems is inconsistent with the phase rule. Although derived for the specific case given in the title, the relationships developed ore applicable to all conditions of binary systems. Sample calculations illustrating the methods are included. LIMITATIONS OF THE METHODS PRESENTED Equations (4) , (5) , and (8) for

Industrial & Engineering Chemistry Research, 2017

Vapor pressure, heat of vaporization, liquid heat capacity, and ideal gas heat capacity for pure compounds between the triple point and critical point are important properties for process design and optimization. These thermophysical properties are related to each other through temperature derivatives of thermodynamic relationships stemming from a temperature-dependent vapor pressure correlation. The Riedel equation has been considered an excellent and simple choice among vaporpressure correlating equations 1 but requires modification of the final coefficient to provide thermodynamic consistency with thermal data. 2 New predictive correlations with final coefficients in integer steps from 1 to 6 have been created for compounds with limited or no vapor pressure data, based on the methodology used originally by Riedel. 3 Liquid heat capacity was predicted using these vapor pressure correlations, and best final coefficient values were chosen based on the ability to simultaneously represent vapor pressure and liquid heat capacity. This procedure improves the fit to liquid heat capacity data by 5-10% (average absolute deviation), while maintaining the fit of vapor pressure data similar to other prediction methods. Additionally, low-temperature vapor pressure predictions were improved by relying on liquid heat capacity data.

2015

The isobaric vapor-liquid equilibrium data predictions for the binary system of cyclopentyl methyl ether and cyclopentanol were obtained using UNIFAC and modified UNIFAC Dortmund method. Group identification was done by using artist free software with Dortmund Data Bank . The interaction parameters in the UNIFAC and modified UNIFAC Dortmund method, for the ether group (-CH3O) and alcohol (-OH), were used to predict VLE data. Thermodynamic consistency of the predicted VLE data had been checked by the Herington method. The predicted data were correlated with Van Laar, Wilson and NRTL activity coefficient models. The binary interaction parameters of models had been obtained by regression. The predicted VLE data of UNIFAC method were fitted much more accurately than that of modified UNIFAC Dortmund method by these activity coefficient models Van Laar, Wilson and NRTL.