从过量体积推算液相活度系数与汽液平衡数据

本文运用统计热力学导出了一个直接由过量体积数据推算液相活度系数的新模型--EVLAC模型,本模型主要从“双液胞腔”与“局部组成”等概念出发,通过配分函数导出y-x表达式和V^E-x表达式,仅需要一个温度下的V^E-x数据即可推算出不同温度下盼恒温y-x,数据和不同压力下的恒压y-x数据,在不需要增加多元可调参数的情况下,可推广应用至多元体系。     

置换法测定气液平衡

本文工作在流通法的原理上提出一种不分析组成测定汽液平衡的新方法。它通过配置样品与汽液平衡测定仪汽相浓度区或液相浓度区的等体积置换,测定配样组成所对应的露点或泡点。置换法的基本原理双循环汽液平衡测定仪在达到操作稳态时,存在着三个浓度区间的划分以及相互之间的物料平衡关系。流通法的基本作法是,将平衡液相回流或平衡汽相回流引出,并以等流量的配制样品注入混合区。溶质量随时间的变化规律为,     

New analytic apparatus for experimental determination of vapor–liquid equilibria and saturation densities

A new experimental apparatus for performing simultaneous determination of high-pressure vapor–liquid equilibria (VLE) and saturated densities was developed in this work. The experimental methodology was verified by measuring these properties for the carbon dioxide + 1-propanol and carbon dioxide + 2-propanol systems from 313 to 363 K. The apparatus is based on the static-analytic method for VLE determinations and was slightly modified by coupling a vibrating U-tube densitometer to obtain saturated densities for both vapor and liquid phases. VLE measurements agreed with previous literature data and were correlated with the Peng–Robinson equation of state coupled to the Wong–Sandler mixing rules. Saturation densities at temperatures above 313 K have not been published up to now.     

New high-pressures vapor-liquid equilibrium data for the carbon dioxide + 2-methyl-1-propanol (isobutanol) binary system

New vapor-liquid equilibria (VLE) data at 333.15, 343.15, and 353.15 K and pressures up to 130.0 bar are reported for the carbon dioxide + 2-methyl-1-propanol (isobutanol) system. The experimental method used in this work was a static analytical method with liquid and vapor phases sampling using a rapid online sampler injector (ROLSITM) coupled to a gas chromatograph (GC) for analysis. Measured VLE data and literature data for carbon dioxide + 2-methyl-1-propanol system were modeled with the Soave-Redlich-Kwong (SRK) cubic equation of state with classical van der Waals (two-parameter conventional mixing rule, 2PCMR) mixing rules. A single set of interaction parameters that lead to a correct phase behavior was used in this work to model the new VLE data and critical points of the mixtures in a wide range of temperature and pressure. The SRK prediction results were compared to the new data measured in this study and to available literature data.

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New high-pressures vapor-liquid equilibrium data for the carbon dioxide + 2-methyl-2-propanol binary system

New vapor-liquid equilibria (VLE) data at 323.15, 333.15, 343.15, and 353.15 K and pressures up to 112.9 bar are reported for the carbon dioxide + 2-methyl-2-propanol system. The experimental method used in this work was a static analytical method with liquid and vapor phases sampling using a rapid online sampler injector (ROLSI?) coupled to a gas chromatograph (GC) for analysis. Measured VLE data and literature data for carbon dioxide + 2-methyl-2-propanol system were modeled with the Soave-Redlich-Kwong (SRK) cubic equation of state with classical van der Waals (two-parameter conventional mixing rule, 2PCMR) mixing rules. A single set of interaction parameters that lead to a correct phase behavior was used in this work to model the new VLE data and critical points of the mixtures in a wide range of temperature and pressure. The SRK prediction results were compared to the new data measured in this study and to available literature data.

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Correlation,verification and prediction of vapour–liquid equilibria using equation of state with association term: II. Alcohols + non-aliphatic hydrocarbons

An equation of state with association term was used to correlate all available binary VLE data sets for mixtures of alkanols with non-aliphatic hydrocarbons. The self association of alkanols was described using a uniform set of parameters. The cross association between alkanols and aromatic compounds was taken into account. The verification of the VLE data for mixtures of alkanols and non-aliphatic hydrocarbons is described and recommended data are given.The method of prediction of the VLE in the investigated mixtures is described. The recommended data were compared with the results of the prediction.     

Extension of Huron-Vidal-type Mixing Rule to Three-parameter Harmens-Knapp Cubic Equation of State

In this paper was extended the HV-type mixing rules to Harmens-Knapp cubic equation state (HK CEOS). The new HV-type mixing rule with HK CEOS was tested for Vapor-liquid equilibrium(VLE) of different polar and nonpolar systems. The tested results are in good agreement with existing experimental data within a wide range of temperatures and pressures. In comparison with the VDW mixing rule, the new mixing rule gives much better predictions for the VLE of nonpolar and polar systems.     

A review of Barker’s activity coefficient method and VLE data reduction

The method of Barker is a popular scheme for determination of activity coefficients from total pressure measurements. A comprehensive review of this method is presented in this study. While discussing this technique various aspects of (vapor + liquid) equilibrium (VLE) data reduction process including types of algorithms applied, roles of saturated vapor pressures and equilibrium vapor compositions data, and types of objective functions used are analyzed. Activity coefficient or liquid state models frequently used in VLE data reduction are shown and their comparisons are investigated. More so, advantages and limitations of Barker’s method are demonstrated.     

用二元交互作用函数预测高压下多组分体系的气液平衡

用和体系的状态有关且满足不变性条件的二元交互作用函数,结合F函数修改的立方状态--方程FRKS方程,预测高压下多组分体系的气液平衡.选择15个三元体系及其组分二元系来检验方法的可行性,这些体系覆盖了从简单的接近理想溶液行为的体系到高度非理想体系.计算结果表明,该方法不仅能相当精确地关联各种类型二元系的气液平衡,而且能在仅用组分二元系参数的条件下较准确地预测所考察的所有三元体系的气液平衡     

Prediction, fine tuning, and temperature extrapolation of a vapor liquid equilibrium using COSMOtherm

As our entry for the third industrial fluid property simulation challenge, the COSMO-RS method in its COSMOtherm implementation has been used to predict the vapor liquid equilibrium (VLE) of ethanol and 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea) at 343.13 K. The absolute prediction of the VLE without any system specific adjustments already yields a reasonable agreement with the experimental data provided for the binary mixture at 283.17 K. Because the special emphasis of the this challenge is state conditions transferability, we also considered two special ways of fine tuning to the experimental data provided for this VLE at 283.17 K. The first way of fine tuning was by fitting of correction charges, the second was by adjustment of a single van der Waals (vdW) interaction parameter. Since vdW parameters used in COSMOtherm are the weakest part of the COSMO-RS parameterization, the fine tuning of the vdW parameters is considered as physically most plausible. Therefore our final prediction of the VLE ethanol and HFC-227ea at 343.13 K is based on the vdW fine tuning.