液态聚合物的内压与状态方程

由热力学关系建立了一个液态聚合物的状态方程.聚合物的热压力由对应状态原理得到,内压力由Lennard-Jones(6,12)势能函数导得.状态方程包含3个有明确物理意义的特性参数,能够满意地关联各种液态聚合物的pVT数据.对18个均聚物和4个共聚物的比体积关联结果表明,总的平均绝对偏差在0～50 MPa压力范围内为0.00042 cm³•g^-1,在全部实验压力范围内为0.00063 cm³•g^-1,优于Simha-Somcynsky方程算得的结果.     

PREDICTION OF THERMAL PRESSURE COEFFICIENTS AND INTERNAL PRESSURE IN BINARY LIQUID MIXTURES

1 INTRODUCTIONThe internal pressure of liquids plays an important role in study on liquids and solu-tions.Internal pressure may serve as a measurement for the intermolecular force.Furthermore,internal pressure is capable of giving indications on entropy changes withthe changes in volume during mixing,as can be seen from the following thermodynamicrelationship:     

COMMENTS ON CUBIC EQUATIONS OF STATE BASED UPON THE INFINITE PRESSURE LIMIT

We examine a recently proposed modification to equations of state of the Van der Waal's type that involves using an infinite pressure limit of the equation to derive new mixing rules for the attractive term parameter. Results on some example systems including both vapor-liquid and solid-supercritical fluid equilibria show that the proposed modification does not appear to enhance the equation over its conventional one-fluid form. It appears that the fundamental inadequacy of the repulsive force term in such equations, for dense fluids, cannot be easily overcome by added complexity for the attractive term expression. Hard sphere reference systems on the other hand provide a more accurate repulsive force term.     

A REDUCED VAPOR PRESSURE EQUATION BASED ON THE THEOREM OF CORRESPONDING STATES

A reduced vapor pressure equation based on the theorem of corresponding states is proposed in this work by the use of the third parameter to and the fourth parameter X. This equation yields an overall average absolute deviation of 1.09% for 111 normal fluids involving a total of 6968 vapor pressure data points, and 0.67% for 20 polar fluids involving a total of 1516 data points, respectively. A relationship of estimating acentric factors is obtained by applying the reduced vapor pressure equation at the normal boiling point. This relationship is very accurate for the prediction of the values of the acentric factor     

氟里昂类物质的饱和液体黏度和导热系数相互推算的对应态方法

引言 导热系数和黏度是重要的运输性质,是工程设计和应用中的基础数据.     

基于微扰理论的表面活性剂水溶液表面状态方程

应用微扰理论并借鉴二维气体理论的处理方法,建立了非离子表面活性剂水溶液的表面状态方程。将微扰理论与压力方程相结合,建立了离子表面活性剂水溶液的表面状态方程。运用提出的状态方程,分别对6种烷基聚氧乙烯醚、辛基酚聚氧乙烯醚、十二烷基硫酸钠等表面活性剂水溶液的表面压数据进行了关联,并利用关联所得的参数预测了其他种类的烷基聚氧乙烯醚及辛基酚聚氧乙烯醚和十二烷基硫酸钠水溶液在不同温度下的表面压。关联和预测的精度均较高,结果令人满意。     

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.     

立方型状态方程用于蒸发热的计算

推导出立方型状态方程计算纯流体蒸发热的新公式,该计算式的特点是式中含有能量参数对温度的导数 da/dT,而与 a(T)无关。根据这一公式对立方型状态方程推算蒸发热进行了比较分析,提出a(T)与 da/dT 相互独立的计算方法,并用 Peng-Robinson 方程对70多种物质(包括烃、醇、卤代烃、酮、无机气体等)进行了关联计算,蒸汽压和蒸发热的平均相对误差分别为0.70%和1.33%。     

方型状态方程在高压相平衡中的研究及应用

对近年来状态方程的研究及其在高压相平衡计算中的应用状况作了综述分析。以ＰＲＳＶ方程为基础，通过实际计算考察和评价不同混合规则在复杂体高压汽液平衡、超临界流体／固体体系相平衡计算中的性能     

INTERNAL PRESSURE AND SOLUBILITY PARAMETER FOR LIQUIDS

Based on a modified van der Waals model, in which the excluded volume is expressed as a linear function of density, the internal pressure and the physical contribution of two - dimensional solubility parameter suggested by Bagley et al. can be expressed as functions of density and a size dependent parameter A. A group contribution method for estimating parameter A and then the solubility parameter has been developed. Average relative deviation of the predicted solubility parameters in comparison will the experimental values for more than sixty liquids including non- polar and polar species as well as those with strong hydrogen bonding is 0.8%. Further correlation with topological indices of molecules makes this method applicable to various isomers of saturated alkanes. Average relative deviation of prediction for 34 saturated alkanes is only 0.6%.     

基于化学缔合的链状YUKAWA流体的状态方程

从Yukawa流体出发,采用化学缔合的统计力学理论建立了链状Yukawa流体的分子热力学模型,其亥氏函数由作为参考流体的硬球Yukawa流体的贡献和链节成键的贡献两部分组成.采用链长为2的链状Yukawa流体压缩因子的Monte Carlo模拟结果关联得到成键贡献项中空穴相关函数,对势能函数参数λ=1.8和λ=3.0时链长为4和8的链状Yukawa流体的压缩因子的预测与Monte Carlo数据能很好地吻合,比Wang和Chiew的微扰理论结果更好.     

CORRELATION OF DIFFUSION COEFFICIENTS FOR LIQUIDS AND DENSE FLUIDS WITH TEMPERATURE AND PRESSURE

On the basis of the free volume theory and activation energy concept,a fundamental equation whichtakes into account the effects of temperature and pressure has been developed.By introducing differentexpressions for the free volume and activation energy,several equations for fluid diffusion coefficients were derivedaccordingly.With the van der Waals free volume and intermal energy formula,a three-parameter model for fluiddiffusion coeffficients at moderate pressure was obtained.The grand average absolute deviation percent of 345data points (44 systems)for self-and infinite dilute inter-diffusivities is 2.32,against the results of the model ofCohen and Turnbull,4.13.In particular,by means of the modified Carnahan-Starling free volume equation,afour-parameter model with average abosolute deviation percent 2.64(30 systems,644 data points)for theestimation of dense fluid inter-and self-diffusivities at high pressures and in supercritical conditions was derived.The derived model is superior to the method of L     

液体内压的预测和新溶解度参数值

引　言在作者先前的工作[1]中 ,已由液体混合的热力学模型导得一个比Ｓｃａｔｃｈａｒｄ -Ｈｉｌｄｅｂｒａｎｄ正规溶液理论更加严格的过量Ｇｉｂｂｓ自由能表达式 .据此 ,定义了一个新的溶解度参数Δ =λ/ｍ =δ2 /λ (1 )式中　δ2 =ΔＶａｐ Ｕｍ/Ｖｍ,为液体的内聚能密度 ;λ =ｐ1/2ｉ ,为液体内压的平方根 ;ｍ =ｐｉＶｍ/ΔＶａｐＵｍ,为Ｈｉｌｄｅｂｒａｎｄ参数 .不难看出 ,当ｍ =1时 ,Δ =δ ,故传统的Ｈｉｌｄｅｂｒａｎｄ溶解度参数δ只是式( 1 )的一种特殊情况 ,由于一般液体的ｍ不等于1 ,故Ｈｉｌｄｅｂｒａｎｄ溶解度参数必须…     

A GENERALIZED EQUATION OF STATE FOR POLAR AND NON-POLAR FLUIDS BASED ON FOUR-PARAMETER CORRESPONDING STATES THEOREM

A new generalized equation of state for polar and non-polar fluids based on the corresponding states theorem is developed, f n addition to two critical parameters, four parameters are required; two for the calculation of volumetric properties and two for the calculation of pressure and departure functions. Parameteres for more than 100 polar and non-polar fluids are given. Comparison with the existing generalized state equations showed that the new method, in general, shows a better agreement with the experimental data. The absolute average deviation is 0.48% for the vapor pressure and 0.32% for the saturated liquid volume.     

关于立方型状态方程的若干评述和讨论

对在状态方程,尤其是立方型状态方程,研究与开发过程中的几个重要问题,从若干层面进行了评述和讨论。评价了统计力学在开发状态方程中的作用,并指出了其局限性。通过综述温度函数的发展状况,给出了温度函数仍然是纯经验性等看法。对混合规则的发展状况以及各种不同类型的混合规则进行了评述和比较。     

一些半经验立方型流体状态方程的近似推导

将virial方程高次项的贡献近似地整合到三项截断式中，然后利用第2 virial系数B的近似式对virial方程的二项及三项截断式进行不同的形式变换和扩展，近似地得到了Martin、Abott的总包性立方型方程以及一些半经验立方型方程或其类似形式，如van der Waals、Clausius、Redlich-Kwong、Usdin-McAuliffe (Fuller)、Martin、Peng-Robinson、Patel-Teja、Harmens-Knapp、Tong-Liu、LHSS、MKS、Du-Guo、CCOR、SIRK，Lee-Edmister方程等，这表明上述方程具有一定的统计力学基础.另用同样方法得到了9个新的三次方程，其中有些方程在形式和参数方面具有较大的灵活性，因而可能具有较好的应用前景.     

EQQUATION OF STATE BASED HYDRATE MODEL FOR NATURAL GAS SYSTEMS CONTAINING BRINE AND POLAR INHIBITOR

A new thermodynamic model for gas hydrates was established by combining the modified Patel-Teja equation of state proposed for aqueous electrolyte systems and the simplified Holder -John multi -shell hydrate model. The new hydrate model is capable of predicting the hydrate formation/dissociation conditions of natural gas systems containing pure water/formation water (brine) and polar inhibitor without using activity coefficient model. Extensive test results indicate very encouraging results.     

EQUATION OF STATE BASED HYDRATE MODEL FOR NATURAL GAS SYSTEMS CONTAINING BRINE AND POLAR INHIBITOR

1 INTRODUCTIONIn the past two decades,as large reserves of hydrocarbons were discovered in the formof natural gas hydrates stored in deep oceans and permafrost regions such reserves mayturn out to become a tremendous energy source in the future.Among the challengingproblems emerged from offshore oil/gas exploration and production,hydrate research re-ceived new impetus.     

A CUBIC EQUATION OF STATE BASED ON A SIMPLIFIED HARD-CORE MODEL

The Redlich-Kwong (RK) equation of state introduced in 1949 has been considered the most accurate two-constant-parameter cubic equation of state. The other cubic equations which are more accurate than the RK equation contain either three, or more, parameters and/or their parameters are temperature- dependent. A New two-constant-parameter cubic equation of state, $ is introduced using a simplified molecular theory of hard-sphere fluids for its repulsive term. This two-constant-parameter cubic equation of state appreciably increases the accuracy of thermodynamic property predictions and phase equilibria of pure fluids and flluid mixtures over the equations of this category.