由状态方程计算混合物的临界性质

混合物的临界性质(T_c,P_c和V_c)在高压相态及分离过程计算中具有重要意义.由于实验测定的困难,文献与手册中有关混合物临界性质的数据(与混合物组成有关)极少,如何通过计算确定这些性质成为热力学界所关心的问题之一.混合物的临界性质一般可通过以下三种方法进行估算:(1)通过相包线计算间接确定;(2)由经验或半经验关联式计算;(3)基于严格的临界状态的热力学准则应用状态方程直接计算.第一种方法过于繁琐;而第二种方法普适性较差,且缺乏与汽液平衡计算的热力学一致性;第三种直接计算法可消除上述缺点,因而近年来受到较大重视.Heidemann和Khalil(1980)以及Peng和Robinson(1977)所提出的直接计算法已成功地应用于烃类非极性混合物临界性质的预测.本文的目的主要是将直接法扩充应用至极性混合物临界性质的计算,并改进前人对临界比容的预测.在前阶段工作(徐东海和郭天民,1989)基础上,本文作了较大扩充与修改.按Heidemann和Khalil由Helmholtz自由能导出的下列临界状态判别准则Q△n=0,△n~T△n=1(1)及偏导数矩阵Q中的元素q_(ij)与三次式中三阶偏导数的表达式结合状态方程(可导出逸度f_i表达式)联解方程式(l)和(2)便可求得组成指定的混合物的临界性质.为将直接法扩展应用至极性混合物,作者选用了Leet等(1986)提     

由PR状态方程计算液体混合物表面张力

在界面化学位的基础上，定义了组分的界面逸度系数，推导出一个新的液体混合物表面张力的表达式，同时用Ｐｅｎｇ－Ｒｏｂｉｎｓｏｎ状态方程计算液体混合物体相和表面相组分的逸度系数，从而实现了由状态方程计算液体混合物表面张力。文中用这一新模型计算了５６个二元体系的表面张力，平均相对偏差为３．３８％，说明该方法是可行的。     

由PR状态方程计算液体混全物表面张力

在界面化学位的基础上，定义了组分的界面逸度系数，推导出一个新的液体混合物表面张力的表达式，同时用Ｐｅｎｇ－Ｒｏｂｉｎｓｏｎ状态方程计算液体混合物体相和表面相组分的逸度系数，从而实现了由状态方程计算液体混合物表面张力。     

含CO2气体混合物在60℃时的混合性质

测定了６０℃和２－６００ｂａｒ时由ＣＯ２和Ｈｅ、Ａｒ、ＳＦ６以及ＣＨＦ３组成的等分子二元混合物的压缩因子，根据纯物质和混合物的压缩因子计算了压力混合效应和过剩体积。对于真实气体混合性质的描述，本文采用五参数的ＢＡＣＫ方程，方程计算值与实验值符合较好。     

MH状态方程使用DDLC混合规则计算混合物临界轨迹

<正>一、引 言状态方程能否精确地描述流体混合物热力学性质,建立合适的混合规则是一个重要因素.近十年来,许多研究者把局部组成概念引入立方型状态方程,建立了与密度有关的局部组成(DDLC)混合规则,将两类重要的热力学模型——状态方程和活度系数方程联系起来,大大地改善了状态方程应用于高密度区时的柔软性,改进了状态方程描述极性一非极性、含超临界组分等高度非对称体系的精确度.作者将局部组成概念引入多参数的MH状态方程,椎导了MH方程的DDLC混合规则,用于计算高压汽液平衡和二元混合物临界轨迹.本文将介绍后者的计算情况.     

苯酐反应器出口气体混合物的特性

通过建立苯酐反应产物分布的模型,计算出了不同装置负荷下苯酐反应产物的分布情况,继而计算出不同装置负荷下的反应产物混合物的特性,如苯酐和水在反应产物混合物中的露点,气体冷却器中有苯酐冷凝下来所必需的负荷,部分冷凝器在各种负荷下对反应混合物中的苯酐的捕集率,切换冷凝器在不同温度下对苯酐的捕集率,从而对装置操作参数的优化提供了理论依据。     

一个修正的多参数状态方程

从统计热力学的观点出发，结合经验的状态方程，对方程参数作出适当的修正，得到一个改进的适用范围广的多参数状态方程。结果表明，修正的状态方程精度较高。     

Lee-Kesler状态方程在含极性组分物系粘度计算中的应用

将Ｌｅｅ Ｋｅｓｌｅｒ 状态方程用于Ｄｅａｎ Ｓｔｉｅｌ 粘度方程中求解密度值,计算了８ 组含极性组分的液体混合物粘度,得出较准确的计算结果。     

发展马丁-侯方程作为水的专用方程

发展了适用于极性物质水的MH方程。由线性最小二乘法拟合单相区和汽液共存区的PVT及相平衡数据 ,得到方程常数 ,并用统计方法检验了方程的有效性。计算结果表明 ,饱和蒸汽压和摩尔体积误差一般小于0 .6。单相区体积和压力平均误差分别为 0 .3 %和 2 .5 %。与Bender方程相比 ,新方程准确度更高     

A Modified Peng-Robinson Equation State for Prediction of Gas Adsorption Isotherm

This research proposes a modified two-dimensional Peng-Robinson equation model to predict adsorp-tion isotherm in adsorbate-adsorbent systems. The parameters of the proposed model are calculated by using the op-timization of experimental data for the different single gas adsorption systems at various temperatures. The experi-mental adsorption equilibrium data of adsorbate-adsorbent systems was compared with the calculated results in our proposed model and the two-dimensional Hill-deBoer equation model. The proposed model as indicated in the re-sults shows a better prediction of the experimental results compared with two others.     

Design and Implementation of a Gas Generating System for Complex Gas Mixtures and Calibration Gases

A test gas generation system for complex gas mixtures designed to mimic real industrial gas matrices with traces raging from low pptv to high ppmv level and minor and main components ranging from low to high percentage levels with variable relative humidity levels (0–80 % RH) is presented. It combines different gas generation methods to study fragmentation patterns under controlled conditions by means of a proton transfer reaction time-of-flight mass spectrometer, the application of alternative feedstocks in catalytic processes as well as the performance of gas purification and conditioning processes.     

A New General Equation of State

A new general equation of state is presented, which can be used to express not only common cubic equations of state, but also quartic equations of state and so on. Main advantage of the new equation over the previous general equations is that it is in simple form, and is easy to manipulate mathematically.     

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。     

Tao-Mason状态方程扩展用于重正烷烃(英文)

In our previous paper we extended the Tao and Mason equation of state (TM EOS) to refrigerant fluids, using the speed of sound data. This is a continuation for evaluating TM EOS in predicting PVT properties of heavy n-alkanes. Liquid density of long-chain n-alkane systems from C 9 to C 20 have been calculated using an analytical equation of state based on the statistical-mechanical perturbation theory. The second virial coefficients of these n-alkanes are scarce and there is no accurate potential energy function for their theoretical calculation. In this work the second virial coefficients are calculated using a corresponding state correlation based on surface tension and liquid density at the freezing point. The deviation of calculated densities of these alkanes is within 0.5% from experimental data. The densities of n-alkanes obtained from the TM EOS are compared with those calculated from Ihm-Song-Mason equation of state and the corresponding-states liquid densities (COSTALD). Our results are in favor of the preference of the TM EOS over other two equations of state.     

VLW爆轰产物状态方程的发展及应用

以国际公认理论完美的维里(VIRIAL)状态方程为基础,建立了VLW炸药爆轰产物状态方程,简述了VLW炸药爆轰产物状态方程的形成背景,呈现了VLW方程的推导过程;应用VLW方程计算了军用高能炸药、民用工业炸药、凝聚相炸药、气相燃料空气炸药的爆轰性能参数,以及火箭推进燃烧性能参数,推导了爆轰产物的热力学函数(内能、熵、化学位等)。结果表明,应用VLW方程计算的参数结果准确合理;成功解决了高温下(T*>20)高级维里系数计算难题,准确表达了爆轰条件下的维里方程属性。     

Equation of state for gaseous nitrogen determined from isotropic model potentials

A four‐term virial equation of state was combined with isotropic potential models to predict accurate volumetric and caloric thermodynamic properties of nitrogen in the gas phase. The parameters of the model potentials were determined from a fit to acoustic data alone; no other data was used. For nitrogen, it was only necessary to approximate the fourth virial coefficient at the level of interactions that contained no more than one triplet potential; higher order approximations offered no further advantage. It was shown that the four‐term virial equation was more accurate than the three‐term analogue. It was found that predicted virial coefficients became consistent with experimental values when temperature was >150 ± 30 K; conversely, below this range virial coefficients predicted by the model did not agree with experiment. It was believed that predicted fourth virial coefficient was reliable and accurate only above about 150 K. Predicted compressibility factors deviated by <0.05% at pressures of up to 10–12 MPa, or densities up to 4 mol/dm³ (≈0.4ρ_c), only when temperature was >220 K. Values of enthalpy predicted from the equation of state showed good agreement with experimental data.