LCVM型混合规则扩展用于多参数状态方程以关联混合物汽液相平衡

基于两参数状态方程提出的LCVM混合规则是将以无穷压力为参考态的HV混合规则与以零压力为参考态的MHV1混合规则线性结合而得的,尽管没有理论基础,但对于计算非极性、极性体系给出了较好的结果.因而研究借鉴获得LCVM混合规则的思路将LCVM混合规则扩展到多参数状态方程中,即将HVOS混合规则与MHV1混合规则进行线性结合,并通过引入两个对比参数λ0,λ∞给出了适合多常数状态方程的新LCVM型混合规则.在新的LCVM型混合规则中,参数δ决定了MHV1和HVOS混合规则的相对贡献,该参数可由模型在高压和低压下拟合二元混合物的泡露点得到,通过拟合得到的值约为0.21;混合规则中的活度系数模型可以利用由低压区关联出的GE模型.采用该新混合规则模型,在较宽的温度与压力范围内,结合Harmens-Knapp(HK)方程对包括非极性体系、极性体系等在内的20种二元混合物进行了相平衡计算.计算的结果与实验数据吻合得很好.该模型与采用VDW混合规则模型的相平衡计算结果比较表明,该模型的关联精度有了很大的提高,可以在较大的温度与压力范围内关联多种体系的汽液相平衡数据.但是在混合规则中,参数b,c是依赖于经验获得,因此还有待于进一步的研究.     

流体汽液相平衡混合规则研究进展

混合工质汽液相平衡学术内涵丰富且应用广泛，而混合规则是决定混合物性描述准确与否的关键因素。综述了具有代表性的混合规则，包括原始的二次型、非二次型、密度型、状态方程-超额自由能型等混合规则，评价了其在流体汽液相平衡的描述能力，辅以数学推导介绍了其发展的动机及存在的优劣，以期对将来混合规则发展提供思路。     

碳酸二甲酯-草酸二甲酯二元常压汽液相平衡

用气相单循环的玻璃平衡釜测定了碳酸二甲酯－草酸二甲酯二元系统的常压汽液相平衡数据。用积分法对其进行了热力学一致性检验。回归得到了草酸二甲酯的Antoine方程参数。用Wilson活度系数方程对实验数据进行了关联,取得了较好的结果。     

固液相平衡模型研究进展

固液相平衡研究对反应混合物的溶剂选择、药物结晶过程及工厂安全评估等方面具有重要的意义,是分离及提纯工艺的设计基础。介绍了活度系数模型、状态方程模型、经验模型、溶剂物性关联模型及人工神经网络法5类固液相平衡模型。重点综述了活度系数模型、状态方程模型及经验模型模型,并对模型的适用性进行了分析。基于目前相平衡模型研究进展,对未来的发展方向进行了展望。     

UNIFAC基团贡献法估算甲醇-碳酸二甲酯的汽液相平衡

以甲醇-碳酸二甲酯为实验物系，在考虑了汽、液混合物非理想性的情况下，用UNIFAC基团贡献法估算了液相活度系数，用维里方程求算了汽相逸度系数。并最终给出了此二元物系在不同压力下的汽液相平衡数据，结果表明其共沸组成(甲醇摩尔分数)随压力的增高而增大，当压力从0．1MPa增至1．5MPa时，共沸组成由0．890增加到0．960。最后将常压下的相平衡数据与实验值进行了对比，二者的最大偏差为9．4％。     

汽液相平衡计算方法的研究进展

主要介绍了汽液相平衡计算的两种方法的研究进展,包括状态方程法和活度系数法.分析了方法中所涉及的各种方程的适用范围及其优缺点,提出了汽液相平衡计算的研究方向.     

用修正的UNIFAC模型参数及HVOS规则预测汽液平衡

利用Orbey和Sandler提出的HVOS混合规则,PR状态方程与Larsen的活度系数模型相结合建立了无限压力下汽液平衡模型,模型给定状态方程中不随温度变化的参数C*=-0.623 23。用大量的汽液平衡数据在广泛的温度范围内修正了12组MLUNIFAC基团相互作用参数,并用修正的和原始的参数分别对含醇、酸、酮、水、腈和胺等极性二元体系进行了预测。结果表明,体系预测精度显著提高,大部分体系汽相组成的绝对偏差低于4.00×10-2,压力的相对偏差低于6.00%。     

费托合成油品体系相关二元物系汽液平衡预测方法的评价

比较了基于不同α函数（BM、SRW）和不同混合规则（MHV2、WS、HG）的PR、RKS状态方程,SR-POLAR和PC-SAFT状态方程,以及UNIF-DMD和UNIF-HOC活度系数方程在费托合成油品体系预测汽液平衡的能力。结果表明：对于弱极性体系,各种计算方法结果接近,偏差均较小;对于非缔合极性体系,UNIF-DMD、RKS-MHV2和RKS-HG方程计算结果比较准确;对于含水缔合极性体系,RKS-MHV2方程和UNIF-HOC方程计算结果比较准确;含酸缔合体系,UNIF-HOC方程和SR-POLAR方程显示了最准确的预测能力;其他缔合极性体系,UNIF-HOC方程和SR-POLAR仍然显示了最高的计算精度,RKS-MHV2和RKS-HG次之;PC-SAFT缺少交互参数时,非均匀体系计算偏差较大。     

用改进R-K方程和链转子状态方程预测合成氨体系的汽液相平衡

本文应用改进R-K状态方程和Van Laar型活度系数方程预测不同温度和压力下合成氨体系五个关键组分的相平衡常数;同时用立方型链转子状态方程加以预测,将两者所得结果与实验值相比较,后者更接近于实验值。     

乙苯或二甲苯和异丙醇二元体系等压汽液相平衡

用经E llis汽液平衡釜验证的自制汽液平衡釜测定了异丙醇+乙苯及异丙醇+邻二甲苯、间二甲苯、对二甲苯4个二元液系在压力为99.80 kPa时的等压汽液平衡数据,并进行了热力学一致性检验。用UNIQUAC模型处理了实验数据,得出了二元体系的混合自由能。这不仅为二元液系混合体系充实了实验数据,还为二元液系的热力学研究丰富了理论依据。     

SRK方程结合超额Gibbs自由能规则预测汽液平衡

SRK方程结合范德华混合规则应用于极性体系会产生较大误差,而结合超额Gibbs自由能(GE)型混合规则能得较好的结果。Wong-Sandler(WS型)混合规则是基于无穷大压力的GE型混合规则,文中对提出一种基于常压的改进型WS(MWS型)混合规则,利用SRK方程分别结合WS型和MWS型混合规则对多个二元极性体系汽液平衡进行预测。比较结果表明,采用SRK方程结合MWS型混合规则预测汽液平衡结果一般优于WS型混合规则。     

Ion exchange equilibria in binary and ternary systems

Simple mathematical models for binary and ternary ion exchange equilibria were developed to predict selectivity coefficients and resin capacities from a simple experiment to within acceptable engineering accuracy limits. Batch equilibrium experimental investigations were undertaken to test the models for binary systems (Ni-Na, Cu-Na, Zn-Na, Cd-Na and Pb-Na) and ternary systems (Ni-Cu-Na, Cd-Ni-Na, Cd-Cu-Na and Pb-Cu-Na) with a commercial DOWEX HCR-W2 resin. Binary parameters were used to predict ternary equilibria. It was found that good agreement between the predicted and experimental values was obtained when the binary selectivity coefficients of the two competing heavy metal ions in the ternary system were either almost equal or differed by a factor as large as five.     

Fluid-phase equilibria in binary systems containing an ionic liquid. Application of the Percus-Yevick-van der Waals equation of state

Following some simplifications to reduce the computational effort, the Percus-Yevick-van der Waals equation of state is used to calculate the isothermal total pressure of a binary liquid system containing one volatile nonelectrolyte liquid and one nonvolatile ionic liquid. Pure-component parameters a and b are found from pure-component enthalpy-of-vaporization and liquid-density data. The single binary parameter a₁₂ is obtained from Henry's constant for the nonelectrolyte in the ionic liquid. For 10 binary systems, calculated total pressures are in good agreement with experiment although in a few systems observed total pressures are slightly higher than those calculated in the region where the ionic liquid is dilute. Brief attention is given to a few binary systems with a miscibility gap.     

SRK方程α的分析和比较

Alpha functions of Soave-Redlich-Kwong （SRK） equation of state proposed by Soave, Twu, and Luo were different in mathematic tendency. They were compared in modeling methane-alkanes equilibria with van der Waals mixing rule and Modified Huron-Vidal （MHV1） mixing rule, respectively. Results showed that Luo＇s alpha function was a little more accurate than Soave＇s, and Twu＇s alpha function lacked accuracy in modeling methane-alkanes equilibrium. SRK equation of state was expanded as virial form, and then the equivalent terms were contrasted with terms of virial equation of state. Results showed that Soave＇s and Luo＇s alpha functions matched the tendency of virial coefficient better than Twu＇s, and Luo＇s alpha function matched better than Soave＇s in wide temperature range, which sustained the conclusions of phase equilibria calculation. Luo＇s alpha function keeps decreasing when Tr〉 1 and becomes negative at sufficient high temperature, thus the conventional cubic equation of state expressed pressure as the sum of repulsion pressure PR （〉0）, and attraction pressure PA （〈0） could be improved to be the sum of hard-sphere repulsion pressure PH （〉0） and intermolecular force pressure P1 （P1〈0 at low temperature and p1〉0 at sufficient high temperature）.     

Measurement and prediction of high-pressure vapor-liquid equilibria for binary mixtures of carbon dioxide + n-octane, methanol, ethanol, and perfluorohexane

We report the measurement of high-pressure vapor-liquid equilibrium data for binary mixtures of carbon dioxide + n-octane, +methanol, and +ethanol systems at 313.14 K and carbon dioxide + perfluorohexane at 303.15-323.15 K. The experimental data were collected using a new simple apparatus for measuring high-pressure vapor-liquid equilibria and correlated using a modified SRK equation with the three-parameter conventional mixing rule proposed by Adachi and Sugie. The SAFT-VR equation of state has also been used to predict the phase behavior and found to be in good agreement with experimental data. For the carbon dioxide + methanol, carbon dioxide + ethanol and carbon dioxide + perfluorhexane systems simple Lorentz-Berthelot combining rules can be used to determine the cross interactions and predict the phase behavior. For the carbon dioxide + n-octane system cross interaction parameters fitted to experimental data are needed in order to capture the non-ideal phase behavior exhibited by this system.     

状态方程模拟醇胺系统的密度和汽液相平衡

通过考虑醇胺分子间的缔合作用,结合先前开发的非缔合变阱宽链流体状态方程(SWCF-VREOS)建立了一个缔合方阱链流体状态方程,并利用方程模拟了醇胺系统的密度和汽液相平衡。通过关联不同温度下醇胺的饱和蒸气压和液体体积得到了18种醇胺流体的分子参数,新方程计算的饱和蒸气压和液体密度总的平均误差分别为0.94%和0.88%。结合简单的混合规则,将此方程扩展到混合系统。研究发现,建立的方程可预测二元和三元醇胺混合物的密度。当引入一个与温度无关的可调参数时,方程能满意关联二元系统的汽液相平衡数据,并可进一步预测多元混合系统的汽液相平衡,预示着新方程可模拟醇胺系统的相行为。     

PSRK模型的修正混合规则及其应用于聚合物溶液汽液平衡的预测

To extend the PSRK(predictive Soave-Redlich-Kwong equation of state)model to vapor-liquid equilibria of polymer solutions,a new EOS-gE mixing rule is applied in which the term ∑ xi ln(b/bi)in the PSRK mixing rule for the parameter a,and the combinatorial part in the original universal functional activity coefficient(UNIFAC)model are cancelled.To take into account the free volume contribution to the excess Gibbs energy in polymer solution,a quadratic mixing rule for the cross co-volume bij with an exponent equals to 1/2 is applied [b1/2 ij= 1/2(b1/2 i b1/2 j)].The literature reported Soave-Redlich-Kwong equation of state(SRK EOS)parameters of pure polymer are employed.The PSRK model with the modified mixing rule is used to predict the vapor-liquid equilibrium(VLE)of 37 solvent-polymer systems over a large range of temperature and pressure with satisfactory results.     

立方扰动硬链状态方程GE混合规则及其应用

扩展了立方扰动硬链(CSPHC)状态方程在天然气工业中通常遇到物质的纯组分参数, 并建立了纯组分参数的普遍化关联式; 将过量Gibbs自由能混合规则引入CSPHC状态方程, 以应用于高度非对称体系与极性体系相平衡性质计算。结合MPHC活度系数模型及Wilson 活度系数模型, 对13组二元体系的汽液平衡性质获得较满意的结果。