无限稀释液相扩散系数的新关联方程

根据由统计力学所得扩散阻力方程并结合粘度定义，推导出无限稀释液相扩散系数基本方程。对常见的分子进行适当的假设，得到了无限稀释液相扩散系数方程的通用形式和一般形式。本文主程的准确性较高，且具有较强的理论基础和较广泛的使用范围。     

用改进的Eyring方程推算无限稀释扩散系数

在Ｅｙｒｉｎｇ绝对速率理论的基础上，提出一个关联扩散自由体积的关系式，从而得到改进的扩散系数计算方程，可从纯物质粘度推算无限稀释扩散系数，方程不含任何待定参数．对８２个各类体系共３３２点扩散系数数据，计算平均相对偏差为１２．１％，而Ｗｉｌｋｅ－Ｃｈａｎｇ方程对同样体系的计算偏差为１４．８％，Ｓｉｄｄｉｑｉ－Ｌｕｃａｓ方程的偏差为１２．３％．     

超临界水中NaCl无限稀释扩散系数的研究

The molecular dynamics(MD) was employed to simulate the diffusion coefficient of sodium chloride at infinite dilution in supercritical water from 703.2K to 763.2K and from 30 MPa to 45 MPa ,Based on the simulated data and the Patel-Teja(PT) equation of state and the Liu-Ruckenstein equation,an equation for calculating the diffusion coefficient of NaCl at infinite dilution in supercritical water is proposed,Both the agreement between the simulated and correlated data,and that between the simulated and predicted data of diffusion coefficients for NaCl in supercritical water ranging from 703.2K to 803.2K and from 25 MPa to 50MPa show that this equation is applicable for calculation of diffusion coefficients.     

液体纯物质的粘度及扩散系数与蒸发潜热间的关系

本文结合流体的普遍化范德华理论和粘度与扩散系数的自由体积模型,导出了纯物质的液体粘度及分子扩散系数与蒸发潜热间的关系式。对30种纯物质的粘度与蒸发潜热间的关联误差为1.45％;对20种物质的自扩散系数与蒸发潜热间的关联误差为2.9％。所选物系包括强极性、弱极性和非极性分子。本工作为建立传递性质与平衡性质间的关系,以及提出粘度及扩散系数与温度间的新关联式打下了初步基础。     

气相扩散系数的简易测定

1引言菲克定律中的扩散系数DAB代表单位浓度梯度下的扩散通量，表证某个组分A在介质B中扩散的快慢，是物质的一种传递属性，类似于传热中的导热系数。但比导热系数更为复杂：它至少要涉及两种物质，因而有多种多样的组合方式；同时随温度的变化较大，还与气体的总压有关。故文献中扩散系数的数据难以齐全。而应用半经验公式估算时，精确度又欠佳[1]．本文介绍一种简易方法，用以测定两组分混合气体的扩散系数。对其测定原理进行严谨而完整的分析论证，并通过实例说明其应用。2测定原理如图1所示，在一细长直立的玻璃管底都盛入纯液体入不…     

溶剂在交联硅橡胶中无限稀释扩散系数测定

气相色谱法测定溶剂与聚合物材料之间的相互关系是一个快速、准确、方便的方法，为此利用气相色谱法测定了小分子溶剂在不同交联剂含量的交联硅橡胶中的无限稀释扩散系数，并研究了交联剂用量对无限稀释扩散系数的影响，这为研究交联硅橡胶特性提供了新方法。     

有机物在超临界CO2中无限稀释扩散系数的分子动力学模拟

根据物质的实验临界常数或与物质最基本分子结构相关的Joback或Lydersen临界常数估算法得到物质的临界常数,结合Lennard-Jones流体的对比状态方程,按照对应态原理得到了38种有机物分子的新的Lennard-Jones位能参数。由这些位能参数结合简单的组合规则,首次对一些高附加值的复杂实用有机物在313.15　K、16MPa的超临界CO     

超临界或高压CO2中无限稀释扩散系数的模拟

采用分子动力学模拟的方法对超临界二氧化碳的自扩散系数及甲醇和乙醇在超临界二氧化碳中的无限稀释扩散系数进行了模拟计算。结果表明,分子动力学模拟方法可较准确地反映二氧化碳的扩散性质,计算无限稀释扩散系数取得了与实验值较吻合的结果。采用这种新方法可以准确有效的地预测超临界体系的扩散性质,将会更加广泛应用于工程设计,因此分子动力学模拟作为先进的研究手段会得到越来越广泛的应用。     

有机物在超临界CO_2中无限稀释扩散系数的分子动力学模拟

根据物质的实验临界常数或与物质最基本分子结构相关的Joback或Lydersen临界常数估算法得到物质的临界常数,结合Lennard-Joned流体的对比状态方程,按照对应态原理得到了38种有机物分子的新的Lennard-Jones位能参数.由这些位能参数结合简单的组合规则,首次对一些高附加值的复杂实用有机物在313.15 K、16 MPa的超临界CO_2中的无限稀释扩散系数采用分子动力学模拟的方法进行了研究.模拟结果表明,采用这种新思路可以有效地预测超临界体系的扩散性质,满足超临界萃取工艺开发和设计的需要.     

3种芳香烃在聚乙烯膜中的无限稀释扩散系数

基于Hadj-Romdhane和Danner色谱过程的数学模型 ,采用反相气相色谱法在 348.2～ 36 3.2K温度范围内测定了苯、甲苯和乙苯 3种芳香烃溶剂在聚乙烯膜中的无限稀释扩散系数 .实测数据的关联结果表明 ,采用空穴自由体积替代Vrentas-Duda自由体积理论方程中自由体积项的修正方程 ,能很好地描述溶剂分子的无限稀释扩散系数随温度的变化关系 .同时在修正方程的基础上建立了一般化自由体积方程 ,并对该方程的预测能力进行了探讨     

气液色谱法测定正己烷在不同类型固定液中的无限稀活度系数

利用气液色谱法测定了正己烷在正十六烷～正二十三烷、角鲨烷、角鲨烯、二苯甲烷、联苄、丁二酸二正丁酯、丁二酸二异辛酯、已二酸二正辛酯、癸二酸二正辛酯中不同温度下的无限稀活度系数。由Ｆｌｏｒｇ－Ｈｕｇｇｉｎｓ理论预测的正己烷的活度系数与实验值相近，由此进一步得到了二组分体系的相互作用参数值及各溶剂的溶解度参数值。     

CORRELATION AND PREDICTION OF LIQUID DIFFUSION COEFFICIENTS IN BINARY SYSTEMS

A theoretical model to correlate and predict the liquid diffusion coefficients in binary sys-tems has been developed.Based on this mode1 the diffusion coefficient of 73 binary systems have beencorrelated,the overall average deviation of the correlation for diffusion coefficients is 0.009.Forbinary systems the diffusion coefficients have been predicted from vapor liquid phase equilibrium(VLE)and vice versa.     

溶剂极性对超临界乙醇中无限稀释扩散系数的影响

INTRODUCTION Ethanol has more accessible critical properties(Tc =241 ℃, Pc =6.38 Mpa) than water and stronger solubility power than carbon dioxide. Nearcritical and supercritical ethanol is a compressible fluid exhibiting great tunability with both temperature and pressure.     

PREDICTIVE EQUATION OF TRACER LIQUID DIFFUSION COEFFICIENT FROM VISCOSITY

1 INTRODUCTIONAccurate data on molecular diffusion are required for the design of chemical and physi-cal processes where mass transfer plays an important role.Expressions for estimatingtracer diffusion coefficients(i.e.binary diffusion coefficients at infinite dilution)areavailable for a number of different systems .The Akgerman and Gainer equa-tion has been known to give good predictions for the diffusion coefficients of gases inliquids.This study provides an approximation approach for predicting diffusioncoefficients of binary liquid systems from their viscosities.     

ACTIVITY COEFFICIENTS AT INFINITE DILUTION IN SOLVENTS WITH TWO FUNCTIONAL GROUPS

Activity coefficients at infinite dilution for 26 solutes (paraffins, cycloparaffins, olefins, aromalics, n. chloroparaffins, chloroform, tetrachloromethane, acetates, ketones, alcohols and nitriles) in five solvents containing two functional groups of the same nature were determined by gas-liquid chromatography. The solvents employed were hexanediol, nonanediol, hexanedithiol, dodecanediamine and dodecanedinitrile. The influence of the second functional group is suggested from both the absolute values of the activity coefficients as well as from the selectivity values of these solvents with respect to paraffin-aromatic separation.     

高压乙醇中的无限稀释扩散系数:实验测定与模型评价

The infinite diffusion coefficients of benzene, toluene, naphthalene, pyridine and p-nitroaniline in ethanol were measured by Taylor dispersion technique under 318-473 K and 0-16 MPa. The measurement accuracy of the established apparatus was first checked. The measured diffusion coefficient of the five organic solutes in ethanol did not change with pressure at low temperature, but it was significantly reduced with pressure increase when the temperature is higher than 373 K. Of the correlations available for polar solvents, the modified Wilke-Chang equation, the Yang-Zhang equation as well as the He-Yu equation were used to calculate the infinite diffusion coefficient. At low temperature,the three equations all agreed well with experimental results for both polar and non-polar solutes.However, the prediction accuracy was decreased sharply when the temperature was higher than 373 K,where the association factor of the solvent was varied with temperature as well as pressure.     

多孔固体表面扩散问题中Fick定律交叉项扩散系数的确定

对多孔固体表面扩散二元系统给出Fick定律交叉项扩散系数矩阵形式的计算式,并将其推广到三元及多元扩散系统,得到Fick定律交叉项扩散系数普遍化的计算式。