基于黏滞球模型的CPA状态方程应用于醇胺系统相平衡的计算

考虑到醇胺及其混合物中分子间存在缔合作用的事实,结合立方型PR状态方程,通过引入基于黏滞球模型(SSM)发展起来的缔合流体的分子热力学模型,建立了一个新的CPA(cubic-plus-association)状态方程,即CPA-SSM,并将方程应用到醇胺系统相平衡的计算中。通过关联对比温度0.55～0.90范围下醇胺流体的实验饱和蒸气压和液相体积得到了8种醇胺流体的分子参数。结果表明,CPA-SSM方程可满意地计算出醇胺饱和蒸气压和液体密度,总平均误差分别只有0.57%和1.80%。对醇胺混合物,无论是恒压还是恒温系统,只需引入一个与温度无关的可调参数,CPA-SSM方程即可满意关联二元系统的汽液平衡数据,并可进一步预测多元混合物的汽液平衡。     

变阱宽方阱链流体状态方程模拟制冷剂的汽液平衡

应用作者先前基于二阶微扰理论和PY2近似积分方程建立的可变阱宽方阱链流体状态方程模拟了纯制冷剂及其混合体系的汽液平衡。通过关联不同温度下制冷剂的饱和蒸气压和液体体积得到了18种纯制冷剂的分子参数,新方程计算的饱和蒸气压和液体体积总的平均偏差分别为1.11％和0.92％。结合简单混合规则,将此方程扩展到混合体系。研究发现,建立的方程可满意预测制冷剂二元混合体系除临界区附近外的汽液平衡,对两个三元体系汽液平衡的预测也取得了满意的效果,当引入一个与温度无关的可调参数时,关联精度大为提高,预示着新的方程可模拟制冷剂的汽液平衡。     

用密度泛函理论研究非极性混合流体表面性质

应用密度泛函理论研究了二元非极性混合流体的表面性质.分子作为球形链处理,不同分子内的两链节相互作用以硬核Yukawa势能表示.为了避免计算中势能作用数值积分截断导致的误差,采用了合理的长程校正方法.根据微扰理论建立了流体的状态方程以计算汽液相平衡.从纯流体汽液相平衡数据回归得分子的链节作用参数ε/k、d和m_s,这些参数预测纯流体表面张力时可获得较好结果.继而引入混合参数k_ij表示不同分子链节作用情况,计算了6种非极性混合流体的汽液相平衡、表面张力、表面密度剖面.结果表明,本方法应用于二元非极性流体混合物时汽液表面张力计算值与实验值符合良好,同时显示某些二元混合流体表面区可能出现组分的相对富集现象.     

实际流体的微扰理论状态方程研究

在微扰理论和硬球链状态方程基础上,对链状分子间中的氢键作用采用了一种新的处理方法,提出一个新的三参数的实际流体状态方程。将此方程用于关联３３个纯液体的饱和蒸汽压和液体密度,并由所得到的参数预测了汽相的密度。此状态方程比ＡＰＡＣＴ和ＳＡＦＴ状态方程简单,而计算的精确度则相当     

用密度泛函理论研究二元体系的液液界面张力

应用密度泛函理论和统计缔合流体理论建立了二元液液界面的状态方程 ,通过纯流体汽液平衡时的压力数据和液相密度数据回归了非极性流体和极性流体的链节参数 .将界面分层 ,使用已建立的状态方程和回归的纯流体链节参数 ,根据界面各微层达到相平衡时化学势相等的原则计算了液液界面层的厚度和液液界面中的密度分布 ,预测了 16个水 -有机溶剂二元体系的液液界面张力 .计算结果与实验值符合情况良好 .     

链状流体的分子热力学模型(Ⅰ)──纯物质

实际链状流体的分子热力学模型表示为参考流体（硬球链流体）的贡献与一微扰项之和.作者先前建立的硬球链流体的状态方程用于计算参考流体的性质,用Alder等人对方阱流体的计算机模拟结果计算微扰项的贡献,从而建立了实际链状纯流体的分子热力学模型.该模型具有非常简单的形式,用三个与温度无关的分子参数（分子的链数,链节的直径和链节间的方阱位能阱深）可以较好地关联从球形小分子到链状高分子、分子间没有氢键作用的流体的饱和蒸汽压、饱和液体体积和pVT关系     

链状流体的分子热力学模型(Ⅰ)──纯物质

实际链状流体的分子热力学模型表示为参考流体（硬球链流体）的贡献与一微扰项之和.作者先前建立的硬球链流体的状态方程用于计算参考流体的性质，用Alder等人对方阱流体的计算机模拟结果计算微扰项的贡献，从而建立了实际链状纯流体的分子热力学模型.该模型具有非常简单的形式，用三个与温度无关的分子参数（分子的链数，链节的直径和链节间的方阱位能阱深）可以较好地关联从球形小分子到链状高分子、分子间没有氢键作用的流体的饱和蒸汽压、饱和液体体积和pVT关系     

RG-CPA方程计算超临界CO2-醇体系汽液相平衡

综合考虑缔合作用和密度涨落的影响,将经重整化群修正的CPA方程（RG-CPA方程）扩展到二元体系汽液相平衡的计算。通过一个温度下的汽液相平衡数据回归得到二元交互作用参数,预测其他温度下的相平衡。采用这种方法计算了超临界CO₂与醇二元体系的汽液相平衡性质和临界曲线。结果表明,RG-CPA方程预测超临界CO₂与醇二元体系的气液相组成和密度具有较高的精度,液相组分平均绝对偏差为0.032,气相组分平均绝对偏差为0.019。与原始CPA方程相比,RG-CPA方程能更好地预测气液临界曲线。     

基团贡献状态方程的开发与热力学模型参数的理论预测

热力学模型是研究流体相行为和热力学性质的重要工具。理论模型的有效应用离不开模型参数的确定。为赋予热力学模型的预测功能，目前的策略一是建立基团贡献(GC)状态方程(EOS)，二是探索热力学模型参数的理论预测方法。围绕先前开发的变阱宽方阱链流体状态方程(SWCF-VR)，采用基团贡献法思路获得了不同基团对模型参数的贡献值，建立了GC-SWCF方程，证实GC-SWCF方程能满意预测纯物质的密度。进一步将似导体屏蔽模型(COSMO)与SWCF结合，基于COSMO方法获得了192种有机化合物的SWCF方程的模型参数，这是一种不依赖实验数据确定模型参数的理论方法。发现COSMO+SWCF能较好地预测纯物质的密度。引入一个与温度无关的二元交互作用可调参数后，GC-SWCF与COSMO+SWCF都可应用于二元混合物密度与气液相平衡的计算中。     

HFO-1336mzz(Z)环保制冷工质的PC-SAFT状态方程研究

以新型环保制冷工质HFO-1336mzz(Z)作为研究对象,采用链扰动统计缔合流体理论(PC-SAFT)状态方程,通过关联文献中的PVT数据,回归得到了HFO-1336mzz(Z)制冷工质的PC-SAFT状态方程参数。在此基础上,使用MATLAB软件编制了工质的PC-SAFT状态方程计算程序,得到了较为全面的HFO-1336mzz(Z)PVT数据。研究结果表明:PC-SAFT方程关联得到的饱和蒸汽压及饱和液体密度与文献值的平均相对偏差分别为0.40%和0.92%;同时,方程预测得到的压力及密度与文献值的平均相对偏差在超临界区分别为0.96%和1.35%,在液相区偏差分别为1.06%和1.67%。     

R1234yf+CO2和R1234ze (E)+CO2二元混合物的比容平移Soave-Redlich-Kwong方程

采用温度相关比容平移项的比容平移Soave-Redlich-Kwong（VTSRK）方程计算新工质R1234yf和R1234ze（E）的热力学性质以及两种物质与CO₂的二元混合物性质,混合物计算采用van der Waals混合规则,二元交互作用系数由密度数据拟合得到。对纯净物计算与专用状态方程进行对比,VTSRK方程比SRK方程显著改善了液相密度表征效果。对混合物的密度计算结果与实验数据进行对比,对于R1234yf+CO₂二元混合体系方程与实验数据相对均方根偏差为1.17%,对于R1234ze（E）+CO₂二元混合体系相对均方根偏差为0.82%。结果显示,采用温度相关比容平移项的VTSRK方程应用于R1234yf和R1234ze（E）纯流体以及R1234yf+CO₂和R1234ze（E）+CO₂密度性质计算,可获得较高精度。     

Vapor–liquid equilibria of hydrogen chloride,phosgene, benzene,chlorobenzene, ortho‐dichlorobenzene,and toluene by molecular simulation

Vapor–liquid equilibria (VLE) of nine binary mixtures containing hydrogen chloride or phosgene in the solvents benzene, chlorobenzene, ortho‐dichlorobenzene, and toluene as well as the mixture hydrogen chloride + phosgene are predicted by molecular modeling and simulation. The underlying force fields for the pure substances are developed on the basis of quantum chemical information on molecular geometry and electrostatics. These are individually optimized to experimental pure fluid data on the vapor pressure and saturated liquid density, where the deviations are typically less than 5 and 0.5 %, respectively. The unlike dispersive interaction is optimized for seven of the nine studied binaries. Previously unpublished experimental binary VLE data, measured by BASF in the vicinity of ambient temperature, are predominantly used for these fits. VLE data, including dew point composition, saturated densities and enthalpy of vaporization, are predicted for a wide range of temperatures and compositions. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Calculation of surface tensions for liquid mixtures using the SWCF-VR EOS and Butler-type method

A generalized surface tension model for various types of liquid mixtures by coupling the equation of state for square-well chain fluids with variable ranges and Butler type method was presented. Transferable molecular parameters fitted from experimental pVT of pure fluids were used. The reliability of this model were tested with liquid mixtures including 87 conventional fluid mixtures, 20 aqueous alcohol-amine solutions, 12 ionic liquid solutions, 7 polymer solutions, and 4 liquid alloys. The overall average absolute deviations in correlations with one parameter for all binary mixtures, in predictions for all conventional binary mixtures except aqueous solutions and for all ternary mixtures are 1.94%, 1.82%, and 2.69%, respectively. The potential application of the model in simultaneously describing the phase equilibrium and surface tensions was partially verified. The results demonstrate that this model has an overall robustness and reliability in calculations of surface tensions for various liquid mixtures.     

Modeling high pressure vapor–liquid equilibrium of ternary systems containing supercritical CO2 and mixed organic solvents using Peng–Robinson equation of state

High pressure vapor–liquid equilibrium (VLE) of CO₂-expanded organic solvents was investigated using Peng–Robinson-LCVM-UNIFAC equation of state. Bubble pressure of several ternary mixtures was predicted using this model and correlations were developed based only on binary experimental data. A sensitivity study of the LCVM parameter numerical value was done by considering the coherence between the mathematical features of the mixing rule and the quality of the simulation. The results provided by PR-LCVM-UNIFAC were compared with those ones given by Peng–Robinson equation of state using the classical quadratic mixing rules (PR-CMR). Despite the use of two adjustable parameters for each binary system, PR-CMR is not able to provide good results when applied to ternary systems. The capability of PR-LCVM-UNIFAC model to predict liquid mixture density for ternary systems using parameters regressed only from bubble pressure experimental data was also investigated. Due to the lack of liquid density experimental data, it was possible to perform only a qualitative assessment of the density curves calculated by this equation of state.     

凝析气相态行为的模拟

针对含重质烃的多元混合物提出了PR模型参数新的关联方法.对多于7个碳的重烃,其状态方程参数a和b改为通过可由实测数据确定的T_B、(?)和T计算,避免了由不同经验关联式计算的临界参数T_c、P_c和(?)值不一致的缺点.作者将经上述改进的PR模型应用于凝析气相态行为的模拟计算(露点压力、恒质量膨胀和恒容衰竭等过程)取得了较满意的结果.     

EXTENSION OF SOAVE EQUATION OF STATE TO LIQUID DENSITY

On the basis of vapor pressures, volumes of saturated vapor and liquid, both parameters "a" and "b" in Soave equation of state are treated as temperature dependent and an extended Soave equation is proposed in this work. The VLE for 38 pure components including polar substances have been calculated. The comparison of calculated results with experimental data shows the prediction of liquid density is improved over Soave equation without losing the accuracy of prediction in vapor pressure and vapor density.     

局部组成型M-H(81)状态方程

为了改进M-H(81)状态方程在含极性和超临界组分体系汽液平衡计算中的应用,作者将局部组成概念和M-H(81)状态方程相结合,导出了局部组成型的M-H(81)状态方程[DDLC M-H(81)];并对45组低压和高压二元汽液平衡数据进行了关联计算.结果表明:对低压极性体系,汽相组成的绝对偏差和常用的活度系数模型相当,而压力的绝对偏差则略好于上述模型.对于高压体系(包括含超临界组分体系),新模型与单流体模型相比,无论是汽相组成还是泡点压,其计算精度都有明显的改进.     

Extending the range of COSMO‐SAC to high temperatures and high pressures

The range of the predictive Gibbs energy of solvation model, COSMO‐SAC, is extended to large ranges of density, pressure, and temperature for very nonideal mixtures by combining it with an equation of state (EOS) using the Wong‐Sandler mixing rule. The accuracy of isothermal vapor‐liquid equilibria (VLE) calculations based on using the predictive COSMO‐SAC model and separately the correlative NRTL model is compared, each combined with three different forms of the Peng‐Robinson equation of state. All the models considered require the value of the EOS mixing rule binary parameter k_ij. The NRTL model also requires three other parameters obtained from correlation low pressure VLE data. The PRSV + COSMO‐SAC model is showed, with its one adjustable parameter obtained from low temperature data leads good predictions at much higher temperatures and pressures. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1806–1813, 2018