缔合Lennard-Jones流体在纳米缝隙中的界面性质研究

结合改进的基础度量理论(modified fundamental measure theory, MFMT)和一阶平均球近似理论(first-order mean-spherical approximation theory, FMSA), 建立了二缔合Lennard-Jones(LJ)流体在纳米缝隙中的自由能模型. 应用密度泛函理论(Density functional theory, DFT), 研究了界面张力等温线及汽液平衡时的界面张力, 阐明了外场强度、缔合能量和缝隙宽度对汽液界面张力的影响.     

缔合流体在纳米缝隙中的相行为研究

结合改进的基础度量理论(modified fundamental measure theory, MFMT)和密度泛函理论(Density functional theory, DFT), 研究了二缔合Lennard-Jones(LJ)流体在纳米缝隙中的相行为. 根据平衡时两相温度、化学势及巨势相等的原则, 计算了二缔合LJ流体在纳米缝隙中的相平衡. 阐明了缔合能量和缝隙宽度对平衡时分子和单体密度分布、吸附-脱吸等温线及汽液共存等热力学性质的影响.     

White流体重整化群理论的标度性质

平均场状态方程结合重整化群理论的方法能预测流体的临界性质以及远离临界点的热力学性质. 利用经典的参数型状态方程结合White的重整化过程计算了CO2以及多种正构烷烃(C1～C7)的汽液相平衡热力学性质, 并在此基础上讨论了真实流体在临界点附近的非对称性质. 计算结果表明, White的流体重整化群理论能够很好地预测流体的相平衡热力学性质, 但是对于临界非对称性质不能给出与标度理论相符的结果.     

用密度泛函理论研究Lennard-Jones 流体在狭缝中的相平衡

用改进的基础度量理论(modified fundamental measure theory, MFMT)和密度Taylor展开分别表达过剩自由能中的短程作用和色散作用. 流体分子与狭缝壁之间的相互作用以10-4-3势能函数表达. 由巨势最小原理确定Lennard-Jones (LJ)流体在狭缝中的密度分布和过剩吸附量, 所得结果与分子模拟数据吻合良好. 根据平衡时两相温度, 化学势及巨势相等, 计算了LJ流体在狭缝中的相平衡.     

用密度泛函理论研究Lennard-Jones 流体在狭缝中的相平衡

用改进的基础度量理论(modified fundamental measure theory, MFMT)和密度Taylor展开分别表达过剩自由能中的短程作用和色散作用. 流体分子与狭缝壁之间的相互作用以10-4-3势能函数表达. 由巨势最小原理确定Lennard-Jones (LJ)流体在狭缝中的密度分布和过剩吸附量, 所得结果与分子模拟数据吻合良好. 根据平衡时两相温度, 化学势及巨势相等, 计算了LJ流体在狭缝中的相平衡.     

CO_2-甲醇和CO_2-乙醇体系的界面性质

在交叉缔合的均相状态方程的基础上,结合密度梯度理论(density gradient theory,DGT),建立了适用于CO2-甲醇和CO2-乙醇二元体系界面性质研究的状态方程,对CO2-乙醇体系表面张力的关联结果与实验值吻合良好.阐明了CO2分子与甲醇分子和乙醇分子之间的交叉缔合作用对二元体系表面张力计算结果的影响,以及界面相中CO2与醇羟基之间的交叉缔合与温度和压力之间的关系.     

用Yukawa状态方程和重整化群理论计算链状流体的汽液相平衡

结合重整化(Renormalization Group,RG)理论和适用于链状流体的Yukawa状态方程,研究了10个非极性链状流体和6个缔合流体的汽液相平衡和临界性质．16个体系的临界温度Tc,临界压力Pc和临界密度ρc的计算值和实验值之间的平均相对偏差(ARD％)分别为0．44％,1．31％和1．01％．所得结果与实验数据基本吻合．     

van der Waals状态方程与溶液理论

阐明了van der Waals状态方程与溶液理论间的密切关系。由van der Waals状态方程中的内压力和自由体积简捷地导得Scatchard-Hildebrand正规溶液理论、无热溶液理论和Flory-Huggins聚合物溶液理论。表明这些理论都是建立在van der Waals流体的基础上,为进一步改进这些理论提供了一条切实可行的思路。     

基于LFHB 理论模型关联和预测醇+惰性溶剂的1H NMR 化学位移

运用含氢键缔合的格子流体状态方程(LFHB), 仅用一个参数关联了一元醇-惰性溶剂共17个体系29套1H NMR化学位移数据. 并且用关联参数成功预测了不同温度下丁醇+环己烷的化学位移. 所得结果与化学缔合理论的结果进行了比较. 对于某些体系在稀浓度范围LFHB的计算氢键缔合度要低于化学缔合理论的结果. 并且分析了LFHB理论中的物理参数和化学参数对于缔合度计算的不同影响.     

一个新的方阱流体状态方程

将方阱势能函数视为硬球势和一个短程均匀负势的叠加,并由统计力学方法导出了相应的状态方程,这个方程包含两个定标的径向分布函数.利用已知的压缩因子分子动力学模拟数据,回归得到了这两个径向分布函数,从而建立了一个新的方阱流体状态方程.它的吸引项要比Alder等人回归得到的简单得多,与方阱流体压缩因子的MD数据一致性也更好,特别是在高密度区域.     

Study on vapor-liquid equilibria and surface tensions for nonpolar fluids by renormalization group theory and density gradient theory

An equation of state (EOS) applicable for both the uniform and nonuniform fluids is established by using the density-gradient theory (DGT). In the bulk phases, the EOS reduces to statistical associating fluid theory (SAFT). By combining the EOS with the renormalization group theory (RGT), the vapor-liquid-phase equilibria and surface tensions for 10 nonpolar chainlike fluids are investigated from low temperature up to the critical point. The obtained results agree well with the experimental data.     

用重整化群理论研究胶体模型体系的相行为

用yukawa势能函数表达胶体颗粒之间的吸引作用。用Duh-Mier-Y-Teran状态方 程表达液相Helmholtz自由能。用一阶微扰理论、固体硬球径向分布函数解析式和 改进的胞腔模型建立固相状态方程，结合建立的状态方程和重整化群理论。研究了 胶体模型体系的液-液相平衡和液-固相平衡。研究表明，颗粒之间色散作用量程参 数的变化对胶休到本世纪末茶杯 系的相行为有特殊需要影响。所得结果与分子模 拟数据吻合良好。     

Vapor-liquid equilibria simulation and an equation of state contribution for dipole-quadrupole interactions

A systematic investigation on vapor-liquid equilibria (VLEs) of dipolar and quadrupolar fluids is carried out by molecular simulation to develop a new Helmholtz energy contribution for equations of state (EOSs). Twelve two-center Lennard-Jones plus point dipole and point quadrupole model fluids (2CLJDQ) are studied for different reduced dipolar moments micro*2=6 or 12, reduced quadrupolar moments Q*2=2 or 4 and reduced elongations L*=0, 0.505, or 1. Temperatures cover a wide range from about 55% to 95% of the critical temperature of each fluid. The NpT+test particle method is used for the calculation of vapor pressure, saturated densities, and saturated enthalpies. Critical data and the acentric factor are obtained from fits to the simulation data. On the basis of this data, an EOS contribution for the dipole-quadrupole cross-interactions of nonspherical molecules is developed. The expression is based on a third-order perturbation theory, and the model constants are adjusted to the present 2CLJDQ simulation results. When applied to mixtures, the model is found to be in excellent agreement with results from simulation and experiment. The new EOS contribution is also compatible with segment-based EOS, such as the various forms of the statistical associating fluid theory EOS.     

Investigation of the interfacial properties for CO_2-methanol and CO_2-ethanol mixtures

An equation of state (EOS) applicable for the interfacial properties of CO2-methanol and CO2-ethanol mixtures was established by combining the cross-association EOS and the density gradient theory (DGT). The correlated surface tensions of CO2-ethanol mixtures agreed well with the experimental data. The results illustrated the temperature and pressure dependence of the cross-association between CO2 and alcohol hydroxyls in the whole vapor-liquid surface,and the influence of the cross-association on the calcu...     

Density-functional theory for polymer-carbon dioxide mixtures: A perturbed-chain SAFT approach

We propose a density-functional theory (DFT) describing inhomogeneous polymer-carbon dioxide mixtures based on a perturbed-chain statistical associating fluid theory equation of state (PC-SAFT EOS). The weight density functions from fundamental measure theory are used to extend the bulk excess Helmholtz free energy to the inhomogeneous case. The additional long-range dispersion contributions are included using a mean-field approach. We apply our DFT to the interfacial properties of polystyrene-CO(2) and poly(methyl methacrylate) CO(2) systems. Calculated values for both solubility and interfacial tension are in good agreement with experimental data. In comparison with our earlier DFT based on the Peng-Robinson-SAFT EOS, the current DFT produces quantitatively superior agreement with experimental data and is free of the unphysical behavior at high pressures (>35 MPa) in the earlier theory.     

The Calculation of Strong Detonation Parameters

The parameters of strong detonation for Nitromethane (NM) were calculated with the two-phase Repellent-Translation Equation of State(two-phase R-T EOS).The results are quite consistent with the data of quasi-steady strong detonation experiment in NM that contain velocities, pressures and temperatures. This not only tested the calculation method, but also the ZND theory of detonation and the two-phase R-T EOS again. Furthermore, the experiment methods were supported. The strong detonation parameter calculation method with the constant-kequation of state was conditionally confirmed.     

基于化学缔合统计理论的链状流体状态方程

基于化学缔合统计理论的链状流体状态方程(EOS)能够反映实际分子的形状、链节成链、缔合等具体信息,在实际流体热力学性质计算中有着广泛应用.一般的链状流体EOS仅考虑相邻链节间的相关性,我们则借助统计力学和计算机模拟结果在模型中纳入了相间链节间的相关性,获得的硬球链流体(HSCF)模型能够更好地预测模型流体的压缩因子和第二维里系数.以HSCF为参考,引入方阱色散微扰项获得了实际方阱链流体(SWCF)EOS;结合根据黏滞球模型导得的缔合项,进一步构建了缔合流体EOS.最近,我们根据微扰理论和积分方程方法又开发了一新的变阱宽方阱链流体(SWCF-VR)模型.SWCF和SWCF-VREOSs可很好地用于计算小分子、聚合物、离子液体等纯流体及混合物的相行为、热焓、表面张力、黏度等热力学及传递性质,显示了模型良好的工程应用价值.本文就本课题组多年来在自由空间范畴内基于化学缔合统计理论开发链状流体EOS及其实际应用作系统的总结.     

Crossover SAFT equation of state for pure supercritical fluids

A crossover statistical associating fluid theory (SAFT) equation of state (EOS) is used to fit the parameters of eight common pure supercritical fluids (water, ammonia, carbon dioxide, R134a, ethane, propane, ethene and propene) and calculate their thermodynamic properties. Over a wide range including the critical region, the EOS reproduces the saturated pressure data with an average absolute deviation (AAD) of about 1% and the saturated densities with an AAD of about 2%. In the one-phase region, the EOS represents the experimental values of pressure with an AAD of about 1–3%. The results are satisfactory.