优化温度相关力场预测正构烷烃热力学性质

为了实现不同温度下正构烷烃及其混合物热力学性质的准确预测,以正构烷烃（n-C₄~C₁₀）为训练集,通过对全原子OPLS-AA力场中非键相互作用参数（ε）的模拟优化,得到了ε与对比温度（T_r）以及正构烷烃碳原子个数（N_C）的经验关系式。利用该关系式计算出不同温度不同种类的正构烷烃的ε值,预测了正构烷烃纯物质及其混合物的黏度、密度、扩散系数等物性,并将新力场模拟计算值与理论估算值以及实验值进行比较。结果表明,采用优化温度相关力场预测烷烃及其混合物的物性与实验值最为吻合。密度、黏度和扩散系数的预测值与实验值的相对偏差分别小于2%、5%和10%,显著优于目前的理论方法和原OPLS-AA力场模拟计算的预测值。上述温度相关力场参数的确立,对于利用分子动力学模拟方法准确地预测正构烷烃及其混合物的热力学性质具有重要的实际应用价值。     

二氧化碳混合工质临界参数计算模型对比研究

二氧化碳(CO₂)混合工质是具有应用潜力的动力循环工质,临界参数作为CO₂混合工质的关键基础热物性,对其进行准确地计算和预测具有重要意义。采用4种不同类型的计算模型,分别针对CO₂+HFC、CO₂+HFO和CO₂+HC三类二元混合工质的临界温度和临界压力进行了推算,并与公开发表的实验数据和REFPROP数据库计算结果进行对比,分析讨论了各种计算方法对各类CO₂混合工质的适用性。结果表明,Li方法形式简单,混合物临界温度的计算式仅与纯质组分的临界温度及临界体积有关,可用于CO₂+HFC和CO₂+HFO混合工质临界温度的快速推算。对于CO₂+HC混合工质,RK方法计算偏差最小,该类混合物临界参数实验数据点数和套数较多,因此可直接通过RK方法回归得到关联式进行应用。     

费托合成体系气体-高碳烷烃的相平衡计算

选取Peng-Robinson(PR)方程与perturbed-chain SAFT(PC-SAFT)方程,采用单流体混合规则,重点考察了在费托合成工艺条件下的小分子气体(CO,H2,CO2,N2,CH4和C2H6)与高碳烷烃(C20,C28和C36)体系的气液相平衡.结果发现,在对不同碳数高碳烷烃溶剂采用单一交互作用参数时,PC-SAFT与PR方程计算的液相浓度与实验值的总平均偏差分别为1.39%与1.98%.而不考虑交互作用参数时,其误差分别为25.18%与16.195%.对各系统的交互作用参数进行了研究,结果表明,随温度和烷烃碳数的升高,PC-SAFT方程的交互作用参数缓慢升高,而PR方程的交互作用参数则下降,且幅度较大.因此,考虑交互作用参数时,PC-SAFT方程具有更好的计算精度和可外推性.     

采用泰勒分散法测量蜡分子扩散系数

蜡分子扩散系数是蜡沉积预测模型中非常重要的物性参数。为测量蜡分子（高碳数正构烷烃）在液相体系中的分子扩散系数,建立了基于泰勒分散法的扩散系数测量装置,并对装置操作注意事项进行了详细探讨。采用该装置测量了丙酮水溶液、n-C₆+n-C₇溶液以及甲醇水溶液中溶质在溶剂中的分子扩散系数,以文献值对测量值进行校验,验证了装置的可靠性。分别以n-C₁₈、n-C₂₀、n-C₂₂、n-C₂₄、n-C₂₆为溶质,以n-C₇为溶剂,在不同温度、浓度下测量蜡分子在液相体系中的分子扩散系数,并将实验测量值与Hayduck-Minhas关系式计算值进行比较。结果表明：蜡分子扩散系数随温度升高而线性增大,随溶液中蜡分子摩尔分数的增大而以指数形式减小;在相同条件下,高碳数正构烷烃的分子扩散系数低于低碳数正构烷烃的分子扩散系数。采用Hayduck-Minhas关系式的计算结果比实验测量结果平均小50%,应用于蜡沉积预测时,将低估蜡分子扩散质量流。     

基于PR方程的碳酸二甲酯摩擦理论黏度模型

在对文献中发表的碳酸二甲酯黏度实验数据进行全面收集的基础上,将摩擦理论与工程上常用的Peng-Rob inson状态方程(PR方程)结合建立了碳酸二甲酯的液相黏度模型,通过最小二乘法回归得到了模型中的各系数。结果表明:在拟合范围内,碳酸二甲酯黏度模型的计算值与实验数据绝对平均偏差和最大偏差分别为1.78%和6.34%。所建立的黏度模型适用的温度范围为283—383 K,压力范围为饱和压力接近于100 MPa,文章为碳酸二甲酯作为替代燃料等的进一步深入研究和工程应用提供了黏度计算模型。     

烷烃混合物二元相互作用参数的新型关联式

针对偏离二参数对应状态原理的复杂流体,以Mie势能函数和London色散力理论为基础,引入基于Joffee和Stewart虚拟临界规则的Leland分子形状系数,推导得到状态方程中二元相互作用参数k_ij的新型关联式.取Mie势能函数的参数n为3时,无需经过实验数据返算,关联式可直接计算和预测烷烃混合物k_ij;除了物质的临界性质外,k_ij还是温度、组成、摩尔体积、偏心因子和离子化势能的函数.将关联式初步应用于Peng-Robinson状态方程计算烷烃类混合物的临界压力,计算值与实验值平均偏差小于2.40％,取得满意的结果.     

常压下甲醇-聚甲氧基二甲醚二元体系汽液平衡

在101.3 kPa恒定压力下,采用改进的Rose汽液平衡釜测定了甲醇-DMM₃（聚甲氧基二甲醚,聚合度为n,即DMM_n）二元体系汽液平衡数据,并对汽液平衡数据进行热力学一致性检验,结果表明所测定数据符合Gibbs-Duhenm的热力学一致性。用Aspen Plus v7.1计算机软件,分别对Wilson、NRTL、UNIQUAC活度系数模型进行关联,由最大似然法对目标函数进行优化,回归出相应的二元交互作用参数。将关联结果与实验结果相比较,得到关联值与实验值的温度和汽相组成的平均绝对偏差,分别小于0.65 K和0.0065。为化工数据库增添了内容,也为含甲醇、DMM₃体系的工程设计和进一步深入研究奠定了基础。     

聚甲醛二甲醚体系汽液平衡数据的测定与关联

通过改进的Rose汽液平衡釜在常压条件下测定了PODE₂-PODE₃二元体系的汽液平衡数据，对所测得的实验数据进行热力学一致性检验，结果表明所测汽液平衡可通过热力学一致性检验。使用Aspen Plus v8.8 模拟软件，分别对NRTL、Wilson、UNIQUAC活度系数模型进行关联，通过回归得到对应的二元交互作用参数，并将三种模型拟合所得到的汽液平衡数据与实验所得的数据相对比，得到拟合值与实验值的温度和气相组成的平均绝对偏差均不大于0.37 K和0.0044，表明3种模型的拟合结果与实验数据吻合均较好，偏差均在合理范围内。这些工作为化工数据库增添了精馏的基础数据，也为含PODE₂和PODE₃体系的精馏设计与工程设计的进一步深入研究奠定了基础。     

R600a/矿物油的黏度和密度

利用振动弦黏度/密度实验测量系统对R600a/SUNISO 3GS矿物油混合物5种配比(R600a质量分数为100%、95%、90%、85%、80%)下的黏度和密度进行了实验研究,温度范围为253～333 K。实验系统黏度和密度测量的不确定度分别为±2%和±0.2%,温度测量的不确定度小于±10 mK。在获得实验数据的基础上得到了黏度和密度的关联式。黏度实验数据与方程计算值的最大绝对偏差和平均绝对偏差分别为5.73%和1.75%,密度实验数据与方程计算值的最大绝对偏差和平均绝对偏差分别为0.23%和0.07%。为实际制冷系统的优化设计提供了更为可靠的热物性数据。     

乙醇胺乳酸盐离子液体吸收SO2过程中的物理化学性质

测定了常压下乙醇胺乳酸盐-水二元混合体系纯组分及混合液在303.15～333.15 K温度内的密度和黏度, 并对实验数据进行拟合, 通过Jouyban-Acree模型将密度、黏度数据与温度和组成进行关联, 得到关联参数。实验还测定了不同水分含量下该体系饱和吸收SO₂后的密度、黏度。结果表明:该二元混合体系的密度随着温度以及水含量的增大而下降;在水分含量低时该体系的黏度随着温度以及含水量的增大而急剧下降;在水分质量分数超过60%时, 含水量对黏度变化的影响较小。在相同条件下饱和吸收SO₂后, 该体系的密度和黏度比吸收前的略有增大。另外, 分别由密度和黏度实验数据计算不同温度及组成下该二元体系的超额摩尔体积V^E和混合黏度变化Δη, 结果均为负值, 产生了负偏差, 说明离子液体与水之间较强的相互作用。     

N,N-二甲基甲酰胺+醇二元混合物的黏度测定与关联

在288.15~313.15 K和常压下,利用乌氏黏度计测定了N,N-二甲基甲酰胺（DMF）分别与乙醇、丙醇、乙二醇和1,2-丙二醇组成的二元系全浓度范围内的黏度,计算了过量黏度△η和过量流动活化自由能△G^*E。用Redlich-Kister方程对过量黏度进行了关联;用黏度模型如Frenkel方程,Grunberg-Nissan方程,Katti-Chaudhari方程和McAllister方程对实验黏度数据进行了关联和预测,并利用Eyring理论方法计算了流动活化自由能、活化焓和活化熵等热力学函数。结果表明,4个二元系的过量黏度和过量流动活化自由能均为负值,且都随温度降低而偏差增大。过量黏度最低值均发生在DMF摩尔分数约为0.3处。McAllister模型对黏度数据的关联结果最好,预测值与实验值的平均相对偏差最小。比较并分析了DMF与一元醇和二元醇之间分子相互作用的差异。。     

均三甲苯/二异丁基甲醇混合溶剂黏度测定及关联

采用乌氏黏度仪,在常压和293.15～323.15 K温度范围内测定了均三甲苯与二异丁基甲醇混合溶剂以及两种纯溶剂的黏度,计算了不同温度和组成下混合溶剂的超额黏度。用Redlich-Kister方程对超额黏度进行了关联;用Andrade方程、UNIFA-VISCO模型以及Grunberg-Nissan模型对黏度进行了关联与预测。结果表明,混合溶剂的黏度随温度升高和均三甲苯含量增加而减小。超额黏度均为负值,且随均三甲苯含量增加呈U形变化,约在均三甲苯摩尔分数为0.3时达到最低。Grunberg-Nissan模型对黏度数据的关联和预测性最好,预测值与实测值的最大和平均相对偏差分别为12.96%和5.74%。     

Densities and Viscosities of 1-butyl-3-methylimidazolium Hexafluorophosphate [bmim][PF6] ＋ CO2 Binary System： Determination and Correlation

A gas-dissolving device was designed and connected to the falling-body viscometer, which was used to determine the viscosities of liquids in our lab before. The equipment can be used to determine the gas composition, the densities and viscosities of the solution at the same time. The densities and viscosities of [bmim][PF6] ＋ CO2 binary system were determined in the temperature range of 313.2 to 413.2 K and pressure range of 5.0 to 25.0 MPa by the equipment. Then the viscosities of [bmim][PF6] ＋ CO2 binary system at constant temperature, constant pressure, and different temperature and pressure were correlated, respectively. For the correlation at different tempera- ture and different t3ressure for different concentration mixtures the average relative deviation ARD is 0.037.     

借助变阱宽方阱链流体状态方程模拟非电解质体系表面张力和粘度(英文)

The equation of state(EOS)for square-well chain fluid with variable range(SWCF-VR) developed in our previous work based on statistical mechanical theory for chemical association is employed for the correlations of surface tension and viscosity of common fluids and ionic liquids(ILs).A model of surface tension for multi-component mixtures is presented by combining the SWCF-VR EOS and the scaled particle theory and used to produce the surface tension of binary and ternary mixtures.The predicted surface tensions are in excellent agreement with the experimental data with an overall average absolute relative deviation(AAD)of 0.36%.A method for the calculation of dynamic viscosity of common fluids and ILs at high pressure is presented by combining Eyring’s rate theory of viscosity and the SWCF-VR EOS.The calculated viscosities are in good agreement with the experimental data with the overall AAD of 1.44% for 14 fluids in 84 cases.The salient feature is that the molecular parameters used in these models are self-consistent and can be applied to calculate different thermodynamic properties such as pVT,vapor-liquid equilibrium,caloric properties,surface tension,and viscosity.     

Vapor pressure measurement and correlation of acetonitrile+1-butyl-3-methylimidazolium chloride,+1-butyl-3-methylimidazolium tetrafluoroborate,and+1-hexyl-3-methylimidazolium chloride

Vapor pressures were measured for acetonitrile+1-butyl-3-methylimidazolium chloride ([C4mim][Cl]),+1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) and+1-hexyl-3-methylimidazolium chloride ...     

Stockmayer force constants for the viscosity of polar gases

Relationships have been developed for the calculation of the viscosity of a polar gas at atmospheric pressure from macroscopic parameters available for the substance. The molecular force constants for the Stockmayer potential determined by Monchick and Mason from viscosity data were related to the critical constants of the substance and the parameters ω and × defined through the vapor pressure. For 10 polar gases, an average deviation of approximately 3.0% was obtained between experimental viscosities and values calculated with the relationships of this study. The relationships were also utilized to calculate diffusion coefficients for a number of polar binary mixtures.     

立方型状态方程结合Eyring理论在液体混合物黏度计算中的应用

Cubic equations of state (EOS) have been combined with the absolute rate theory of Eyring to calculate viscosities of liquid mixtures. A modified Huron Vidal gE-mixing rule is employed in the calculation and in comparison with the van Laar and the Redlich-Kister-type mixing rule. The EOS method gives an accurate correlation of liquid viscosities with an overall average deviation less than 1% for 67 binary systems including aqueous solutions. It is also successful in extrapolating viscosity data over a certain temperature range using parameters obtained from the isotherm at a given temperature and in predicting viscosities of ternary solutions from binary parameters for either polar or associated systems.     

Calculation of Viscosities of Liquid Mixtures Using Eyring’s Theory in Combination with Cubic Equations of State

1 INTRODUCTON The viscosity, particularly that of liquid mixtures is very important in engineering calculations involved in the process design for petroleum and other chemica industries. Since the successful development of a one-parameter equation for correlating the liquid vis cosity of nonpolar mixtures by Grunberg and Nissan[1] many other models have been proposed. Most of them are based on the corresponding state principle, the absolute rate theory of Eyring[2], or the free volume the…     

SOLUBILITY OF ANTHRACENE IN BINARY ALKANE + 2-METHOXYETHYL ETHER SOLVENT MIXTURES

Experimental solubilities are reported for anthracene dissolved in six binary mixtures containing 2-methoxyethyl ether with n-hexane, n-heptane, n-octane, cyclohexane, methyl-cyclohexane and 2,2,4-trimethylpentane at 298.15 K. Results of these measurements are used to test a mathematical representation based upon the combined Nearly Ideal Binary Solvent (NIBS)/Redlich-Kister model. For the six systems studied, the model was found to provide an accurate mathematical representation of the experimental results, with an overall average absolute deviation between measured and calculated values being on the order of 0.4 per cent or less.