热力学状态方程二元交互作用参数估算模型开发

基于气液平衡理论,建立了热力学状态方程二元交互作用参数估算模型。首先,结合气液平衡理论、状态方程以及相应的混合规则建立气液相平衡数学模型;然后以气相组成误差平方和与压力相对误差平方和之和作为目标函数,并使用计算机编程,利用单纯形法进行优化求解,实现了热力学状态方程二元交互作用参数估算模型的开发;最后,用该模型对5组二元气液平衡体系中的组分二元交互作用参数进行估算,并根据估算出的参数对各体系的气相组成进行预测,结果显示,预测值与实验值的平均相对偏差均小于1％,表明该模型计算结果准确,可应用于气液平衡计算中。     

EOS状态下基于多相流有规栅格理论的水-碳氢化合物两相体系的临界轨迹关系

Quantitative representation of complicated behavior of fluid mixtures in the critical region by any of equation-of-state theories remains as a difficults thermodynamic topics to date.In the present work,a computational efforts were made for representing various types of critical loci of binary water with hydrocarbon systems showing Type Ⅱ and Type Ⅲ phase behavior by an elementary equation of state[called multi-fluid nonrandom lattice fluid EOS(MF-NLF EOS)]based on the lattice statistical mechanical theory.The model EOS requires two molecular parameters which representing molecular size and interaction energy for a pure component and single adjustable interaction energy parameter for binary mixtures.Critical temperature and pressure data were used to obtain molecular size parameter and vapor pressure data were used to obtain interaction energy parameter.The MF-NLF EOS model adapted in the present study correlated quantitatively well the critical loci of various binary water with hydrocarbon systems.     

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。     

壳聚糖-聚乳酸接枝共聚物多孔支架制备

天然聚合物壳聚糖,生物可降解材料聚乳酸,都有着良好的生物相容性,在生物医学领域有着广泛的用途。但是,壳聚糖与聚乳酸各自的性能缺陷导致了这两者单独使用有着很大的局限性。为了改善这两者的缺点,可以利用将聚乳酸接枝共聚到壳聚糖主链上。这样既可以改善壳聚糖不易于加工的缺点,而壳聚糖本身碱性多糖的结构也可以中和乳酸降解过程中所产生的酸性。本文介绍了壳聚糖-聚乳酸接枝共聚体系的制备方法。     

二甲醚-甲醇体系二元交互参数的拟合与评价

本文通过化工模拟软件AspenPlus,液相采用NRTL模型,气相采用PR方程,对二甲醚-甲醇二元体系进行汽液平衡计算时涉及到的二元交互作用参数进行了研究。首先分别选用AspenPlus自带的三个数据库VLE—LIT、VLE—RK和VLE—HOC中二元交互参数进行计算,结果表明,选用数据库VLE—ILK和VLE—Hoc中模型参数时,计算值与实验值吻合较好,并且数据库vLE—RK的计算结果更好。其次利用文献实验数据拟合参数,进行气液平衡计算,与实验结果对比表明本文拟合参数最为适合,即对NRTL模型：a12=1．486,a21=-1．1496,b12=-28．06,b21=194．7,C12=0．0172;PR方程：k12=k21=-0．0605。     

A generalized correlation for the prediction of phase behaviour in supercritical systems

A generalized two parameter model is presented which uses molecular properties of pure fluids to predict interaction parameters in the attractive term of the Peng-Robinson equation of state. The predictive method is based on a consideration of London (dispersive) forces and includes attractive forces between polar and non-polar molecules that result from induction. Polar-polar effects and quantum forces are omitted. A large body of experimental vapor-liquid equilibrium data measured at near and supercritical conditions (that excludes quantum components and polar-polar systems) was used to calibrate the generalized model. Overall bubble point pressure deviations calculated using the proposed generalization were 5.66% for 3240 data points which compares to average deviations of 3.27% obtained by using regressed binary interaction parameters. Average vapor mole fraction deviations were just under 0.01 using both the generalized and the regressed interaction parameters. The sensitivity of predicted phase envelopes to dispersive and inductive term in the generalized correlation is shown graphically for several systems. Comparisons are also made to another recent interaction parameter generalization presented by Nishiumi et al. (1988).     

UNIFAC模型在草酸二乙酯合成体系中的应用

利用原始ＵＮＩＦＡＣ模型对ＣＯ气相催化偶联合成草酸二乙酸产物中的各组分进行了基团划分,用实验测定的二元物系等温汽液平衡数据,关联了ＣＨ２Ｏ／ＨＣＯＯ基团相互作用参数,汽液平衡计算值性实验值比较偏差较大。为提高推算精度,对碳酸二忆是进行新的基团划分,提出了ＵＮＩＦＡＣ新基团ＯＣＯＯ,重新关联基团相互作用参数并进行了汽平稳推算,结果令人满意。     

液体混合物粘度与过量热力学性质的关联(Ⅱ)

利用本文(I)报中提出的二元混合粘度与过量Gibbs活化自由能间的关联式,并以McAllister的多元体相互作用模型关联粘度数据,对九对二元系统(其中三对是含醇系统,一对是醇水系统)进行了从粘度数据推算汽液平衡数据.计算结果与相应的实验值比较,除一对系统的偏差较大外,其余八对的泡点均方根差为0.09—0.80℃,汽相组成均方根差为0.003—0.038.     

A multi-fluid nonrandom lattice fluid model: General derivation and application to pure fluids

A multi-fluid nonrandom lattice fluid model with no temperature dependence of close packed volumes of a mer, segment numbers and energy parameters of pure systems is presented. The multi-fluid nonrandom lattice fluid (MF-NLF) model with the local composition concept was capable of describing properties for complex systems. However, the MF-NLF model has strong temperature dependence of energy parameters and segment numbers of pure systems; thus empirical correlations as functions of temperature were represented for reliable and convenient use in engineering practices. The MF-NLF model without temperature dependence of pure parameters could not predict thermodynamic properties accurately. It was found that the present model with three parameters describes quantitatively the vapor pressure and the saturated density for the pure fluid.     

甲醇-乙酸-丙酸多元体系汽液平衡

用新型泵式沸点仪测定了在100kPa下甲醇-乙酸、甲醇-丙酸、乙酸-丙酸3个二元体系以及甲醇-乙酸-丙酸三元系在不同液相组成时的沸点,并用间接法T-p-x(温度、压力和液相摩尔分数)推算了3个二元体系的汽相平衡组成。3个二元体系活度系数分别用Wilson模型、NRTL模型、Margules模型和van Laar模型进行关联,用最小二乘法求出了它们的液相活度系数模型参数,同时,用这些模型参数来计算它们的汽相摩尔分数。所得的液相活度系数来计算3个二元体系的过量吉布斯自由能函数,且所研究的所有体系中各组分之间不存在共沸点。用3个二元体系Wilson模型参数对所测的三元体系数据进行关联,建立该系统汽液平衡的热力学模型并计算平衡时的汽相摩尔分数和泡点温度。由面积积分法检验这些模型参数计算的3个二元体系相平衡数据,得到很好的热力学一致性。     

A modification of Wong-Sandler mixing rule for the prediction of vapor-liquid equilibria in binary asymmetric systems

Systems consisting of light components and heavy hydrocarbons are highly asymmetric and industrially important. Design and control of facilities for separation and purification of such mixtures require vapor-liquid equilibrium data. Coupling of the cubic equation of state (EOS) with excess Gibbs energy models (EOS/G ^ex models) failed to represent the vapor-liquid equilibria (VLE) of such systems accurately. The main purpose of this work is to present a modification of Wong-Sandler mixing rule with using the composition dependent binary interaction parameter. Vaporliquid equilibria for 30 binary systems are calculated using the SRK equation of state with proposed model and Wong-Sandler mixing rule. Calculated pressures and mole fractions of vapor phase are compared with experimental data. The average absolute percentage deviation indicates that error involved in the application of modified Wong-Sandler model is less than Wong-Sandler model in most cases.     

用变阱宽方阱链流体状态方程模拟离子液体相行为

An equation of state (EOS) for square-well chain fluids with variable range (SWCF-VR) developed based on statistical mechanics for chemical association was employed for the calculations of pressure-volume-temperature (pVT) and phase equilibrium of pure ionic liquids (ILs) and their mixtures. The new molecular parameters for 23 ILs were obtained by fitting their experimental density data over a wide temperature and pressure ranges. The molecular parameters of ILs composed of homologous organic cation and an identical anion such as [Cxmim][NTf2] are good linear with respect to their molecular weight, indicating that the molecular pa-rameters of homologous substances, subsequently pVT and vapor-liquid equilibria vapor-liquid equilibria (VLE) can be predicted using the generalized parameter when no experimental data were available. The new set of parameters were satisfactorily used for calculations of the property of solvent and ILs mixture and the solubility of gas in various ILs at low pressure only using one tem-perature-independent binary interaction parameter.     

甲胺与水多元系常压汽液平衡研究

用新型泵式沸点仪测定了常压下一甲胺-二甲胺-三甲胺-水四元系在不同液相组成时的沸点;由所测的甲胺-水二元系数据,用过量自由焓Q函数间接法推算了与之平衡的汽相组成,再用最小二乘法求出甲胺与水间二元体系的液相活度系数模型参数：甲胺与甲胺间二元体系的液相活度系数模型参数则通过拟合它们与水构成的三元系获取;由所得的最佳二元系参数用于该体系四元系汽液相平衡数据的预测,将计算的泡点与实验测得的沸点作了比较,结果表明两者吻合良好。     

丁烯醛及丁烯醛-乙醛二元体系汽液相平衡模拟

采用Gibbs系综Monte Carlo方法,对TraPPE-UA力场中缺失的烯醛类力场参数进行了补充和验证,为模拟含烯醛体系汽液相平衡奠定基础。分别使用B3LYP 6-311G (d, p)和MP2 6-31G (d, p)方法计算了丁烯醛分子中缺失的键参数、二面角扭转项参数。采用构建的丁烯醛分子的TraPPE-UA力场参数,分别计算了丁烯醛纯组分、丁烯醛与乙醛二元体系的汽液相平衡数据,并将模拟结果与实验值进行比较。丁烯醛纯物质模拟结果与实验数据相比液相密度偏差为0.28%～1.23%,模拟结果表明构建的TraPPE-UA力场对丁烯醛分子具有较高的模拟精度。丁烯醛与乙醛二元体系的模拟结果与实验数据相比最小误差为0.13%,但随着温度上升有增大趋势,最大误差为7.44%。     

Measurement of excess enthalpies using a high-pressure flow microcalorimeter and determination of binary interaction parameters for thermodynamic models

While an equation of state (EOS) plays a critical role in estimating thermodynamic properties, employing it in the determination of binary interaction parameters is extremely important. In general, these parameters can be determined from phase equilibrium data. However, data collection from experiments is a time-consuming and tedious process. In this study, after measuring the excess enthalpies of binary systems containing CO₂ by high-pressure flow isothermal microcalorimetry (IMC), we determined the EOS binary interaction parameters, specifically, the Peng-Robinson EOS binary interaction parameters. These binary interaction parameters obtained by IMC were compared with those obtained by vapor-liquid equilibrium (VLE) experiments. Hence, high-pressure flow IMC appears to be an effective method for the determination of interaction parameters that are used in the estimation of thermodynamic properties. Further, the Flory-Huggins interaction parameters of a binary mixture CO₂ containing with various mole compositions were also estimated by employing high-pressure IMC.     

水盐体系汽液平衡的热力学模型研究

水盐体系的相平衡性质是化工单元操作的基础,在化学化工、海洋、地质等领域有着重要的研究价值。国内外许多学者对水盐体系汽液平衡进行了实验和理论的研究,构筑了各具特色的经验和半经验的模型。针对水盐体系,在NRTL理论的基础上,基于水化作用和混合盐假设建立了能够预测混合体系汽液平衡的活度系数扩展模型。通过对21组二元水盐体系和14组混合体系的关联计算,验证了该模型的可行性;同时,该模型可以采用二元体系参数直接预测计算混合水盐体系汽液平衡。     

UNIFAC模型法计算含己内酰胺体系的相平衡(英文)

An extended liquid-liquid equilibrium (LLE) UNIFAC model is proposed to describe phase equilibria of mixtures containing caprolactam. In this model, caprolactam is introduced as a new group. New group interaction parameters are calibrated from 156 sets of liquid-liquid equilibrium data. The present model gives satisfactory correlation and prediction in liquid-liquid equilibrium, including quaternary systems containing the mixed solvent of an alcohol and an alkane. The model can be applied to predict caprolactam solubility in water and benzene accurately. Freezing point and vapor-liquid equilibrium of binary systems containing caprolactam are also predicted with the extended LLE UNIFAC model. Satisfactory prediction results are obtained.     

Prediction of vapor-liquid equilibria by means of a modified clausius equation of state

The Clausius equation was modified for the calculation of vapor-liquid equilibria in binary and multicomponent systems. In the modification, the three parameters of the equation were considered temperature dependent. Molal volumes of saturated liquid and vapor together with the condition that the fugacities of the vapor and the liquid phase are equal at the condition of equilibrium were used for evaluating the parameters of pure components. Applications were made successfully to systems nitrogen-methane, nitrogen-oxygen, argon-oxygen, nitrogen-argon, argon-methane, carbon dioxide-hydrogen sulfide, carbon-dioxide-propane, hydrogen sulfide-n-butane and nitrogen-argon-oxygen.     

丙酮-乙酸异丙烯酯二元体系常压汽液平衡

用改进的埃利斯(Ellis)平衡蒸馏器测定了丙酮-乙酸异丙烯酯二元系统在常压下的汽液平衡数据,用液相活度模型Wilson、NRTL方程对测定数据进行关联,采用非线性最小二乘法回归出二元系统在常压下的Wilson、NRTL方程参数,Wilson模型与试验值符合良好.汽液相平衡数据经Herrington面积法检验满足热力学一致性.     

Modeling the phase behavior in binary mixtures involving blowing agents and thermoplastic resins

The thermophysical properties of mixtures of thermoplastic resins and blowing agents, together with the knowledge of the solubilities of these components, are the basis for the manufacturing of plastic foams. In this work, the solubilities of blowing agents trichlorofluoromethane, dichlorodifluoromethane, chlorodifluoromehane, and 1,2‐dichloro‐1,1,2,2‐tetrafluoroethane in thermoplastic resins poly(styrene), high density poly(ethylene), low density poly(ethylene), poly(propylene), poly(vinyl chloride), poly(carbonate) and poly(propylene oxide) were modeled by using the Perturbed Chain‐Statistical Associating Fluid Theory (PC‐SAFT) and the Sánchez‐Lacombe equations of state (EoS), fitting a single temperature‐dependent binary interaction parameter. PC‐SAFT is a theoretically based equation of state with three pure component parameters that describe efficiently the thermodynamics of complex systems. Earlier works with this EoS have already predicted the phase coexistence properties of various refrigerants and higher order alkane series compounds, along with their mixtures. The pure component parameters for the blowing agents were obtained by regression of vapor pressure and liquid density data, while the pure component parameters for the thermoplastic resins were obtained by regression of pure liquid PVT data. The parameter estimation was performed by using a modified maximum likelihood method. The solubility results obtained with both EoS have been compared; the results from PC‐SAFT showed a higher accuracy in terms of solubility pressure deviations. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers