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1.
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%。  相似文献   

2.
本文综述应用于汽液平衡计算的立方型状态方程的发展和研究动向。  相似文献   

3.
二元液体混合物的过量体积模型   总被引:1,自引:0,他引:1  
丁舒静  沈晓燕  刘国杰 《化工学报》2004,55(7):1041-1046
按照提出的含醇溶液形成的热力学模型,采用释放和充入组分间引力势能的方法建立了一个过量体积方程,表明含醇溶液的过量体积主要取决于组分解缔和它们间交叉缔合引起的焓变以及模型中释放或充入的组分间引力势能.该方程有良好的通用性,不仅适用于含醇溶液,也适用于非含醇溶液.广泛的检验表明,它能满意地关联各种二元液体混合物的过量体积随组成变化的实验数据.  相似文献   

4.
立方型状态方程研究进展   总被引:2,自引:0,他引:2  
马海龙  项曙光 《河北化工》2007,30(11):16-19
概括了立方型状态方程的进展,介绍了立方型状态方程的特点.分析了各类立方型状态方程存在的问题,提出了解决的方法.对立方型状态方程的应用进行了阐述,指出了其仍然具有很大的研究价值.  相似文献   

5.
体积平移是van der Waals型立方状态方程,使之能精确预测液相密度的一种有效方法。采用多参数方程能同时较准确地计算蒸发坟和液相密度。本文介绍这两种方法近年来的主要进展。  相似文献   

6.
卞白桂  王延儒 《化工学报》1993,44(3):309-314
提出了在参考压力下将过量自由焓(g~E)模型引入状态方程的修正Huron-Vidal混合规则,由g~E模型确定状态方程中混合物的参数,以SRK方程和Wilson模型为例,取大气压为参考压力,计算了16个体系50组汽液平衡,结果表明本文建议的混合规则可直接使用现有文献报道的常压g~E模型参数由立方型状态方程预测常压汽液平衡,并对直接外推预测高压汽液平衡作了尝试.  相似文献   

7.
体积平移是改进vanderWals型立方状态方程,使之能精确预测液相密度的一种有效方法。采用多参数方程能同时较准确地计算蒸气压和液相密度。本文介绍这两种方法近年来的主要进展。  相似文献   

8.
立方型状态方程的混合规则在相平衡计算中的研究   总被引:1,自引:0,他引:1  
汪萍  项曙光 《河北化工》2004,27(2):47-50
对立方型状态方程中所使用的混合规则及其在相平衡计算中的应用状况做了综述分析。将混合规则按二次型、LC型、DDLC型和UNIWAALS型分别进行了介绍和讨论。总结了各种类型混合规则的优缺点和适用范围,并提出了混合规则今后的发展方向。  相似文献   

9.
针对多种立方型状态方程,写出了其通用的表达形式;并通过分析不同情况下通用方程中体积根的特征,得到了立方型通用状态方程气相体积根和液相体积根稳定的求解方法,为立方型状态方程的编程求解提供了一定意义上的指导和借鉴。  相似文献   

10.
张永旺  贾涛 《化学工程》2022,(9):53-56+67
为了更加准确地描述制冷工质纯组分的热力学行为,文中通过拟合HFO类制冷工质的热物性实验数据,回归得到立方型容积平移状态方程的2个可调参数,并将方程的2个可调参数普遍化为关于临界压缩因子的函数。对计算结果进行了分析讨论,分析立方型容积平移状态方程纯流体饱和液相密度和高压液体密度的计算精度。研究结果表明:与原始的PR状态方程和SRK状态方程相比,立方型容积平移状态方程对饱和液相密度和单相液体密度改进显著。以R1234ze(E)为例,验证了文中所建立的立方型容积平移状态方程。VTPR状态方程计算饱和液相密度的平均绝对相对偏差为1.42%,计算高压液相密度的平均绝对相对偏差为0.82%;VTSRK状态方程计算饱和液相密度的平均绝对相对偏差分别为3.58%,计算高压液相密度的平均相对偏差为2.00%。  相似文献   

11.
A generalized cubic equation of state which can represent all the cubic equations is introduced and thermodynamic property relations for it are presented. Five cubic equations of states with respective mixing rules are used to predict molar volumes and vapor pressures of pure alkanes (from methane till n-tritriacontane) and solubilities of solid wax components (high molecular weight alkanes) in supercritical solvents. They are the RK (Redlich-Kwong), MMM (Mohsennia-Modarress-Mansoori), RM (Riazi-Mansoori), PR (Peng-Robinson), and SRK (Soave-Redlich-Kwon) equations of state. The experimental data necessary to compare the equations of state are taken from the literature. It is demonstrated that the SRK equation of state is more accurate for predicting vapor pressures of alkanes. The RM equation of state is shown to be more accurate for predicting molar volumes of saturated and sub-cooled liquid alkanes as well as molar volumes of alkanes in their supercritical condition. For the solubility of wax components in supercritical solvents it is shown that the MMM equation of state gives the least AAD% for the 270 data points of 10 binary systems studied consisting of a high molecular weight alkane and supercritical ethane and carbon dioxide.  相似文献   

12.
Cubic equations of state have received much attention during the last decade1-10 due to their simplicity and practical success. In particular, Abbott2 has discussed a general form of the cubic equation of state and shown that cubic equations of state commonly used for chemical engineering calculations11,12 are specializations of the generic form. The purpose of this work is to further study the flexibility and limitations of the generic form so as to enhance the understanding of recent developments and to provide a guide for future search of better specializations.  相似文献   

13.
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.  相似文献   

14.
Simultaneous representation of vapor-liquid equilibria and excess enthalpies for l-alkanol + n-alkane mixtures has been investigated by means or the PRSV equation of state together with the Wong-Sandier mixing rule. Special attention has been paid on the mixtures of methanol and n-hexane. The results are influenced not only by the selection of a suitable excess Gibbs energy model incorporated in the mixing rule but also by the weighting factors used in the objective function for the evaluation of parameters.  相似文献   

15.
本文提出了一个描述含醇体系过量性质的修正拟化学溶液模型。该模型能关联各种温度下的h~Е,由较低温度下的h~Е关联预测较高温度下的h~Е。用该模型预测了24个含醇体系的汽液平衡,得到了令人满意的结果。  相似文献   

16.
It is shown that by considering the “b” parameter in a cubic equation of state (EOS) as acentric factor/temperature-dependent, liquid densities especially for heavy compounds and the region near the critical point can be estimated more accurately. The proposed equation can also be used for accurate estimation of critical compressibility factors of different compounds, Although the method is applied to Peng-Robinson equation of state (PR-EOS), it can be used for any other cubic equation of state. The proposed method is particularly useful for phase equilibrium calculations of reservoir fluids. The proposed equation requires critical temperature, critical pressure and acentric factor as the input parameters. The proposed equation of stale estimates properties of liquids, vapor-pressure and critical compressibility factors with greater accuracy for pure compounds and mixtures as well as light and heavy compounds found in reservoir fluids.  相似文献   

17.
利用 P R、 S R K、 H K、 P T 状态方程( E O S)计算 C O2 、 C4 H9 O H、 H2 O 纯组份的饱和性质及 C O2 的压缩因子。结果表明, P T 方程对水、二氧化碳的蒸汽压及密度预测较佳。对丁醇的密度推算, P T 方程最佳, P T 方程对丁醇的饱和蒸汽压预测一般。考察了 P T 方程参数的影响,指出应根据相平衡的温度范围选取相应的 P T 方程参数。对 C O2  C4 H9 O H H2 O 体系相平衡的研究宜选用 P T 方程。  相似文献   

18.
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.  相似文献   

19.
The capability of chain-of-rotalor group contribution equation of state (CORGC EOS) in prediction of vapour-liquid equilibria for electrolyte solutions is discussed. A new approach is considered in which salt is considered as a single component and therefore, there is no ion in the solution. The interaction parameters between water and 50 salts are determined and reported. The parameters are temperature dependent and thus, vapour-liquid equilibria calculations can be achieved at moderate temperature. The percent average absolute deviation for prediction of vapour pressure and osmotic coefficient for 50 aqueous solutions are equal to 0.89 and 16.7, respectively. Comparison between the calculated results and experimental data has been performed.  相似文献   

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