共查询到20条相似文献,搜索用时 0 毫秒
1.
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: 相似文献
2.
3.
1 INTRODUCTIONThe CSP(Corresponding States Principle)has been considered to be a useful methodfor the prediction of fluid properties from a minimum amount of information.One ofits form,the shape factor methods is developed through relating the pVT of any interestedpure fluid\"a\"to that of another\"0\"by writing 相似文献
4.
In the two-parameter corresponding states principle(CSP), the critical compressibility factors of the fluid under study(called “α“ fluid) and the reference fluid(called “o“ fluid) must be identical. This is not generally observed in nature. To overcome this limitation, a perfect shape factor CSP is proposed in which the compressibility factors of “a“ and “o“ fluids are corresponded perfectly by introducing a new pressure shape factor 5. Using methane as the “o“ fluid, the shape factors of many fluids are calculated from PVT properties at saturation state and the second virial coefficients. Models are also formulated for the shape factors with the assumption of φ is a function of temperature and volume while θ and δ are temperature dependent only. The models described the shape factors satisfactorily in whole region including vapor, liquid and their co-existing phases. The perfect shape factor CSP could be applied for both polar and non-uolar fluids. 相似文献
5.
A new estimation method was proposed by combining the corresponding state principle with the group contribution method through introducing the concept of assumed-critical properties. Combining it with the Reidel equation, a new acentric factor correlation equation (CSGC-Reidel) was developed. Contribution values of 70 groups were obtained by correlating acentric factor data of 228 organic compounds of 14 type substances including saturated hydrocarbons, unsaturated hydrocarbons, cyclanes, aromatics, oxygen compounds, nitrogen compounds, halohydrocarbons, etc. The average error of acentric factor is 3.52% between the literature data and the predicated with the new estimation method. 相似文献
6.
7.
8.
The present work has devised the approach for efficiently estimating the thermophysical properties of dimethyl ether (DME) at high pressure conditions relevant to its potential application for compression ignition engines. From a practical standpoint, the thermodynamic properties such as density, heat capacity, enthalpy, entropy, and speed of sound are formulated based on a generalized cubic equation of state (EoS). Comparisons with reference data from a highly accurate empirical multi-parameter EoS demonstrate that the present thermodynamic model has reasonable accuracy for engineering purpose over a wide range of pressure and temperature. By combining it with a transport model which extends the kinetic gas theory with dense-fluid correction, the viscosity and thermal conductivity of DME are also reproduced well for the thermodynamic states from compressed liquid to supercritical fluid. 相似文献
9.
A semitheoretical equation of state has been used to correlate residual thermodynamic properties of heavy hydrocarbons. The correlation requires three characteristic molecular parameters obtained from liquid density and vapour pressure data. These parameters are presented for 61 hydrocarbons with molecular weights up to 560 and are correlated with molecular weight and structural features. The correlation is extended to narrow-boiling fractions. Molecular parameters for such fractions are obtained from experimental characterization data (molecular weight, aromaticity, naphthenicity and number of methyl groups per molecule). Calculated vapour pressures and liquid densities are in reasonable agreement with new experimental results obtained from Belridge crude oil. 相似文献
10.
A new approach to the investigation ofvdW type of equations of state (EOS) is developed by embedding a vapor pressure equation and a saturated liquid volume equation into vdW type EOS, which resuits in a new function A^s(T). The A^s(T) possesses the properties of an attractive parameter A(T), and if an EOS is accurate in the whole PVT space, then its numerical wahie equal8 A(T). As a useful tool for investigating EOS, the A^s(T) has been used to make comparisons among RKS, PRSVII, PT and ALS EOS, and to indicate where the shortcomings of the EOS are coming from. Based or. the A^s(T), a possible way to develop at real predictive equation of state is also suggested. 相似文献
11.
12.
13.
14.
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. 相似文献
15.
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
16.
17.
M-H-EOS的理论基础 总被引:1,自引:0,他引:1
根据virialEOS的推导方式 ,从具有分子体积的准理想气体模型出发 ,利用巨正则分布和势能函数 ,从理论上推导了M -H -EOS ,并探讨了M -H -EOS的理论基础。结果表明 ,M -H -EOS与virialEOS具有相同的理论基础 ,只是在考虑实际气体对理想气体在分子体积和分子间相互作用的偏差上做了不同的近似。M -H -EOS为了计算简便 ,在实验的基础上对分子间相互作用做了合理的近似 ,从而避免了高阶virial系数求解困难的问题 ,因此在实用中取得成功。了解M -H -EOS的理论基础 ,对进一步发展和改进M -H -EOS的应用领域和计算准确度具有一定的意义 相似文献
18.
Based on results of saturated vapor pressures of pure substances calculated by SRK equation of state,the factor α in attractive pressure term was modified. Vapor-liquid equilibria of mixtures were calculated by original and modified SRK equation of state combined with MHV1 mixing rule and UNIFAC model, respectively. For 1447 saturated pressure points of 37 substance including alkanes; organics containing chlorine, fluorine, and oxygen; inorganic gases and water, the original SRK equation of state predicted pressure with an average deviation of 2.521% and modified one 1.673%. Binary vapor-liquid equilibria of alcohols containing mixtures and water containing mixtures also indicated that the SRK equation of state with the modified α had a better precision than that with the original one. 相似文献
19.
1 INTRODUCTION Equations of state (EOS), especially, cubic equa-tions of state are frequently used in modeling phase equi-librium for chemical process of designing. Among cubic equations of state, SRK[1] equation of state and PR[2] equation of state are the most commonly used. These two equations of state are similar in form. They are also similar in the correction factor of parameter a. When phase equilibria of mixtures were calculated, equations of state must be combining with mixing… 相似文献