一个新的基团贡献型状态方程——GC-MCSPT方程

将超额Gibbs函数模型与修正的硬球三参数状态方程(MCSPT方程)相结合,导出由基团贡献模型定义的状态方程参数混合规则.直接利用低温下的基团贡献模型参数,如UNIFAC模型、修正的UNIFAC模型(简称MUNIFAC)的交互作用参数,分别预测了二元强极性物系的低压和高压相平衡以及三元强极性物系的汽液相平衡.结果表明,新模型具有广泛的预测能力和满意的预测精度.     

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。     

超额吉布斯自由能-状态方程模型的研究进展

超额吉布斯自由能-状态方程模型是继传统的状态方程法和活度系数法之后计算和预测相平衡的一个新思路。本文根据参考态的不同,将超额吉布斯自由能-状态方程模型进行了分类,并且重点对其中经典模型的优缺点进行了分析和总结。包括:①HV混合规则是第一个被提出的GE-EoS模型,它需要重新回归模型参数;②WS混合规则引入第二维里系数,具有很强的理论依据;③MHV1和MHV2混合规则,可以直接使用活度系数模型现有的参数;④LCVM型混合规则消除了状态方程和活度系数模型的组合项差异,对非对称体系相平衡的表现非常好。文章指出,GE-EoS模型的改进可以从改进状态方程、改进活度系数模型和扩充活度系数参数表3个方面着手。为了适应现在应用的需要,针对非对称体系的GE-EoS模型的开发将是重要的发展方向。     

立方扰动硬链状态方程G^E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化分参数。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。     

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。     

基于混合粒子群算法的复杂相平衡计算方法

对于含有两个部分互溶液相的相平衡问题,采用经典方法收敛困难或易陷于平凡解。为此根据最小Gibbs自由能原理,提出采用混合粒子群算法搜索全局最优解,计算得到系统的最小Gibbs自由能状态,实现复杂相平衡计算。通过改建目标函数,减少计算量,并引入组分相分率,将物料平衡约束转换为规范型立方空间的优化问题,适于粒子群算法搜索。在常规粒子群算法中引入Nelder-Mead单纯形操作,可显著提高搜优的速率和精度。将其应用于甲苯-水-苯胺液液平衡和苯-乙腈-水汽液液平衡计算,取得了良好的效果。     

含盐酸和盐的气液固三相平衡计算

利用亨利定律和溶解平衡方程,建立了气液固同时存在时体系总Gibbs自由能的数学模型,活度系数模型选用Pitzer模型,基于相平衡体系Gibbs自由能最小化原理,运用遗传算法求解,计算NaCl-KCl-HCl-H2O体系固液平衡和气液平衡,并和实验数据进行对比,进一步计算了该体系固液气三相平衡,实现了一步计算固相、液相和气相的组成。     

CO_2-[emim][Tf_2N]二元体系汽液相平衡及超额焓研究

针对CO_2-离子液体二元体系的相平衡问题,搭建了一套汽液相平衡数据测定系统,获得了CO_2-[emim][Tf_2N]二元体系在273.15～328.15 K的汽液相平衡数据,利用PR (Peng-Robinson)状态方程、NRTL (non-random two liquid)活度系数模型结合WS (Wong-Sandler)混合规则对实验数据进行关联,并应用此模型计算得到CO_2-[emim][Tf_2N]二元体系的超额焓。结果表明:关联得到的压力计算值与实验值相比,两者的平均相对偏差为3.87%,与其他模型对比所选模型偏差最小,能够成功地关联CO_2-[emim][Tf_2N]二元体系汽液相平衡数据。进一步完善了CO_2-离子液体二元体系的关联模型。     

三元非共沸混合制冷剂热力性质算法

为了确保计算的精确性,文中采用PRHV与Lee-Kesler-P lǒcker(LKP)模型相结合的方法计算混合工质汽液相平衡参数与焓、熵等热物理性质,即利用Huron-V idal混合规则,采用立方型PR方程和过量G ibbs自由能NRTL模型相结合的PRHV模型预测相平衡参数,在此基础上,由LKP多参数状态方程计算的焓、熵等状态参数。文中验证了这种预测方法的可靠性与准确性,此方法可作为系统循环模拟计算中相平衡及热力参数的精确计算方法。     

α-蒎烯-蒎烷-长叶烯体系汽液平衡及其过量Gibbs自由能与超额焓

采用改进Ellis平衡釜测定了α-蒎烯-蒎烷、α-蒎烯-长叶烯、蒎烷-长叶烯三个二元体系及α-蒎烯-蒎烷-长叶烯三元体系常压汽液平衡数据,经Herington规则检验符合热力学一致性。由汽液平衡数据求出每个二元体系中各组分的活度系数,再关联得到相应的过量Gibbs自由能与超额焓实验值。结果表明,α-蒎烯-蒎烷体系的Gibbs自由能对理想溶液呈现较小的正偏差,而α-蒎烯―长叶烯和蒎烷-长叶烯体系Gibbs自由能对理想溶液呈现负偏差。根据Wilson方程对三个二元体系的过量Gibbs自由能和超额焓进行了计算,关联值与实验值吻合,对α-蒎烯-蒎烷体系最大超额焓为120.48 J×mol~(-1),α-蒎烯―长叶烯体系最大超额焓为401.09 J×mol~(-1),蒎烷-长叶烯体系最大超额焓为685.75J×mol~(-1)。由关联得到的二元体系能量参数推算了α-蒎烯-蒎烷—长叶烯三元体系的过量Gibbs自由能和超额焓,过量Gibbs自由能的实验值与计算值基本吻合,平均相对偏差为1.7147%,该三元体系的最大超额焓为627.16 J×mol~(-1)。     

PSRK-UNIFAC模型在预测煤直接液化高温高压气液相平衡中的应用

为预测煤炭直接液化高温高压气液平衡,将过量吉布斯自由能混合规则和UNIFAC活度系数模型与SRK状态相结合,建立基团状态PSRK-UNIFAC模型。利用该模型对煤液化高温分离器的24种组分气液相平衡进行了预测和关联,计算值和文献值能取得较好一致,并推算了煤液化反应器内气液相组成。结果表明:PSRK-UNIFAC模型可以成功预测高温、高压、强不对称、强极性下的气液相平衡。     

应用PSRK状态方程预测高压汽液平衡

为预测高压汽液平衡,将过量吉布斯自由能混合规则和UNIFAC活度系数模型与SRK状态方程相结合,建立基团贡献状态方程PSRK。利用该状态方程对5个体系在不同压力和温度下的汽液平衡数据进行了关联实验测定的汽相压力和汽相组成与计算结果相比所得的相对平均偏差分别为2．16％和1．01％。结果表明,PSRK状态方程可以成功地预测高压下汽液平衡,其精度高于MHV1和MHV2模型。     

基于无限稀释活度系数模型的状态方程

发展了一种从纯物质的性质参数预测混合物汽液平衡的方法,它是以立方状态方程的过量吉布斯自由能 g~E结合型混合规则和无限稀释活度系数 MOSCED模型为基础,由MOSCED模型预测得到活度系数方程的相互作用参数,从而得到混合规则中的g~E,使得状态方程能在较大温度和压力范围内预测汽液平衡.用此法预测了含极性组分体系常压到较高压力的汽液平衡,结果良好,与UNIFAC基团贡献状态方程的结果相当.     

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     

Study of the High‐Pressure Vapour‐Liquid Equilibria for Strongly Non‐ideal Binary and Ternary Mixtures

High‐pressure vapour‐liquid equilibria for binary and ternary high polar and asymmetric systems are calculated using the Peng‐Robinson‐Stryjek‐Vera equation of state coupled with the Twu‐Coon (TWMR), the Orbey‐Sandler (OSMR) and the Wong‐Sandler (WSMR) mixing rules. Modified UNIFAC model is used for determining the activity coefficient and excess Gibbs free energy. The calculated results are compared with the experimental data and good agreement is observed. The average absolute deviation percents (AAD%)s indicated that the WSMR has less AAD% than other mixing rules in most of cases.     

立方型状态方程含过量自由焓模型的新混合规则

提出了在参考压力下将过量自由焓(g~E)模型引入状态方程的修正Huron-Vidal混合规则,由g~E模型确定状态方程中混合物的参数,以SRK方程和Wilson模型为例,取大气压为参考压力,计算了16个体系50组汽液平衡,结果表明本文建议的混合规则可直接使用现有文献报道的常压g~E模型参数由立方型状态方程预测常压汽液平衡,并对直接外推预测高压汽液平衡作了尝试.     

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.     

A GE/Equation of State Mixing Rule for Vapor-Liquid Equilibria

A new excess Gibbs free energy/equation of state type mixing 0rule was derived by removing the infinite pressure boundary condition imposed by Wong and Sandler. The mixing rule was extensively tested in terms of a comprehensive data base, consisting of 52 simple nonpolar-nonpolar, carbon dioxide containing, hydrocarbon-hydrocarbon, CFC, polar-polar, nonpolar- polar binary and multicomponent systems. Focused on the complete predictive capability, a comparison between the Wong-Sandler and the mixing rule proposed was conducted. The results indicate that the new mixing rule is in general superior to the Wong -Sandler’s, and the binary interaction parameter as required by the latter is removed, which reduces computing effort and is reliable in predictions of vapor-liquid equilibria from low pressures to high pressures.     

High pressure isothermal vapor-liquid equilibria of carbon dioxide+1,1-difluoroethane

Vapor-liquid equilibrium data for the binary mixture of carbon dioxide (CO₂)+1,1-difluoroethane (HFC-152a) were measured at five evenly spaced temperatures of (273.15, 283.15, 293.15, 303.15 and 313.15) K by using a circulation-type equilibrium apparatus in which both vapor and liquid phases were recirculated. The experimental data were correlated with the Peng-Robinson equation of state (PR-EoS) using the Wong-Sandler mixing rules combined with the NRTL excess Gibbs free energy model and the Carnahan-Starling-DeSantis equation of state (CSD EoS). Almost all the calculated values with these two models showed good agreement with the experimental data.