Thermodynamic consistency of vapor‐liquid equilibrium data at high pressure

Abstract

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.

Thermodynamic consistency test for experimental data of water content of methane

“…A previously tuned thermodynamic model, [35][36][37][38] which contains VPT-EoS 39 with nondensity-dependent (NDD) mixing rules 40 was applied to predict the required parameters of the gas phase for the test, which was based on the area test approach derived from the original ''Gibbs-Duhem equation '' 19-21 at constant temperature. [24][25][26][27][28][29] The results showed that 48% of the investigated experimental data are thermodynamically consistent meanwhile this percentage is 27% for inconsistent data and 25% for not fully consistent data. In addition, the results indicated that the measurements of such data must be done accurately and deliberately to be able to use in tuning of the future models for predictions of water contents of gas samples.…”

“…22,23 In recent years, Valderrama and coworkers [24][25][26][27][28] have investigated the applications of numerical thermodynamic consistency methods to various systems including incomplete phase equilibrium data of high-pressure gas-liquid mixtures, 24 high pressure ternary mixtures of compressed gas and solid solutes, 25 high pressure gas-solid solubility data of binary mixtures, 26 vapor-liquid equilibrium data for mixtures containing ionic liquids, 27 and high pressure gas-liquid equilibrium data including both liquid and gas phases. 28 A method especially employed for determining thermodynamic consistency of high pressure gas-solid data by Valderrama and Alvarez, 24 which is based on rewriting the ''Gibbs-Duhem equation'' [19][20][21] in terms of fugacity coefficients 29 has been used in our work. The consistency method employed here can be considered as a modeling procedure.…”

Application of a Thermodynamic Consistency Test to Binary Mixtures Containing an Ionic Liquid

“…The concentrations y 2 were calculated through the bubble point and used for A P and A . The mixture CO 2 + n-butane was already examined by Bertucco et al [12] and Valderrama and Álvarez [13], and has been used here to validate the proposed method. Both papers used the experimental y 2 value.…”

“…Jackson and Wilsak [11] analyzed several consistency tests, mainly for complete high pressure VLE data, that is, experimental PTxy data covering the entire concentration range in both phases; the authors conclude that each test provides different information that, sometimes, can bias the operator. Bertucco et al [12] proposed a consistency test applicable to isothermal, binary VLE data at moderate and high pressures, also for the entire concentration range in both phases. Valderrama and Álvarez [13] presented a new method to test the thermodynamic consistency of incomplete binary VLE data; that is, where PTxy data are not fully available for the entire concentration range, and for low liquid solute concentrations in the vapor phase (mole fractions < 10 -3 ).…”

Modelling the Vapor-Liquid Equilibrium of Polymer Solutions Using a Cubic Equation of State

“…[3,4] Most of these works have been focused on different subjects of the vapor-liquid equilibrium of complex mixtures, such as physical models, [5 -8] equations of state, [9 -12] combining and mixing rules, [13 -16] and optimization methods. [1,17,18] Similarly, the vapor-liquid equilibria in polymer solutions has been intensively investigated.…”