Study on volatility and flash point of the pseudo binary mixtures of sunflower-based biodiesel + methylcyclohexane

The transesterification of sunflower seed oil was carried out in supercritical ethanol without using any catalyst to produce biodiesel. In the present work, methylcyclohexane was added to enhance the vapor pressure of biodiesel. The vapor pressures of mixtures of biodiesel + methylcyclohexane as a function of temperature were measured by comparative ebulliometry with an inclined ebulliometer. The vapor pressures versus composition at different temperatures were obtained. Experimental data of vapor pressures and equilibrium temperatures were correlated by the Antoine equation. A mathematical model was used to predict the flash point of the pseudo binary mixtures. With the regular solution theory, the predictive flash point displays agreement with the experimental data obtained by closed cup test.     

Density,Viscosity and Volatility of Binary Mixtures of Isopropyl Ether and <Emphasis Type="Italic">exo</Emphasis>-Tetrahydrodicyclopentadiene

Measurements of density, viscosity and vapor pressure for binary mixtures of exo-tetrahydrodicyclopentadiene (JP-10) with isopropyl ether are reported at temperatures of (293.15, 298.15, 303.15, 308.15, and 313.15) K over the entire composition range. The excess molar volumes, viscosity deviation and excess Gibbs energies of activation for the binary systems were calculated from the experimental values and fitted with the Redlich–Kister equation. Isopropyl ether was added to enhance the vapor pressure of JP-10. Experimental vapor pressure data were correlated by the Antoine equation. Several semi-empirical equations were used to correlate the viscosity data. The McAllister equation gives relatively satisfactory results for the correlation. The experimental and correlated data could be used in the development of models for mixtures of hydrocarbons with oxygenates.     

Fluid phase stability and equilibrium calculations in binary mixtures: Part II: Application to single-point calculations and the construction of phase diagrams

The methodology presented in Part I of this work is applied to a large number of pressure–temperature flash calculations, and to the automated construction of constant temperature pressure–composition phase diagrams, and constant pressure temperature–composition phase diagrams for binary mixtures modeled with an augmented van der Waals equation of state. An automated prototype implementation of the algorithm is developed for this purpose. We follow the classification of Scott and van Konynenburg [R.L. Scott, P.H. van Konynenburg, Discuss. Faraday Soc. 49 (1970) 87] and present phase diagrams corresponding to non-azeotropic mixtures of the five main types of fluid phase behavior (I–V), studying in detail representative diagrams at constant pressure and constant temperature. Special attention is given to the solution of numerically problematic equilibrium regions, such as those close to three-phase equilibria where metastable and unstable critical points can also be found. Of the order of 10⁴ flash calculations at varying temperatures and pressures, and for different intermolecular parameters of the components in the mixture, have been carried out. The algorithm provides the correct stable equilibrium state for all of the points considered. Despite the fact that our implementation is not optimised for performance, we find that the algorithm identifies the stable solution in difficult regions of the phase space without any penalty in terms of computational time, when compared to simpler regions.     

顺丁烯二酸酐与邻苯二甲酸二甲酯二元体系在4.00, 8.00和12.00 kPa下的等压气液平衡

采用沸点仪测定了顺丁烯二酸酐和邻苯二甲酸二甲酯二元体系在4.00, 8.00和12.00 kPa下的等压气液平衡数据以及纯DMP组分饱和蒸气压数据, 将实验数据回归得到了纯DMP在417~525 K范围内的Antoine方程. 根据实验平衡温度、 压力和组成数据进一步回归得到NRTL方程参数, 推算出平衡气液相组成, 并利用UNIFAC方程对实验数据进行了预测, 其结果与沸点仪测定结果及NRTL拟合的结果基本相符.     

Isobaric (vapor + liquid) equilibria of the binary system maleic anhydride and diethyl phthalate at p = (2.67, 5.33, and 8.00) kPa

Saturated vapor pressures of pure diethyl phthalate were measured with the ebulliometer. And isobaric (vapor + liquid) equilibrium data for the binary system (maleic anhydride + diethyl phthalate) at p = (2.67, 5.33, and 8.00) kPa were determined using the ebulliometric method. The parameters of the NRTL model for the binary system were obtained by calculating equilibrium compositions of the liquid and vapor phase with the experimental equilibrium temperatures, pressures and feed compositions. Moreover, (vapor + liquid) equilibrium data for the binary system were predicted by use of the UNIFAC model. Predicted results were compared with those from the ebulliometric method, and showed good agreement.     

Vapor-liquid equilibrium in selected aromatic binary systems: m-xylene-hydrogen sulfide and mesitylene-hydrogen sulfide

Huang, S.S.-S. and Robinson, D.B., 1984. Vapor—liquid equilibrium in selected aromatic binary systems: m-xylene—hydrogen sulfide and mesitylene—hydrogen sulfide. Fluid Phase Equilibria, 17: 373–382.Vapor and liquid equilibrium phase compositions have been determined for the m-xylene-hydrogen sulfide and mesitylene—hydrogen sulfide binary systems at temperatures of 310.9, 352.6, 394.3 and 477.6 K and at several pressures from the vapor pressure of the less volatile component to the vapor pressure of hydrogen sulfide or to the critical pressure for the system, whichever was higher. The data have been used to calculate equilibrium ratios for each of the components in the binary systems. The results of Eakin and DeVaney (1974) for the mesitylene—hydrogen sulfide system at 310.9 and 477.6 K are also included for comparison.The data presented are useful in evaluating the properties of condensate reservoir fluids containing hydrogen sulfide and aromatic compounds.     

二氧化碳和碳酸二甲酯二元体系的气液相平衡数据

实验测定了二氧化碳和碳酸二甲酯(DMC)二元体系的高压气液相平衡数据. 实验温度为333.0 到393.0 K, 实验压力为3.98 到13.75 MPa. 应用Peng-Robison (PR)立方形状态方程和van der Waals-1 混合规则对实验数据进行了关联计算, 同时得到了二元相互作用参数. 计算结果与实验数据具有很好的一致性.     

Isobaric Phase Equilibria in the Binary Systems Ethyl 1,1-Dimethylethyl Ether + 1-hexene and + Cyclohexene at 94.00 kPa

Abstract

Consistent vapor-liquid equilibrium has been determined for the binary systems 1-hexene + ethyl 1,1-dimethylethyl ether (ETBE) and ethyl 1,1-dimethylethyl ether + cyclohexene at 94.00 kPa. The two systems present slight positive deviations from ideal behavior, can be considered to behave like regular solutions and do not present azeotropic behavior. Pure component vapor pressures are also reported for 1-hexene and cyclohexene. The phase equilibrium of the systems was correlated well by the Wilson, UNIQUAC, and NRTL models and reasonably predicted by the UNIFAC group contribution method. The boiling points of the binary systems were correlated with the Wisniak-Tamir equation.     

Application of Liquid State Models for the Time Efficient Phase Equilibrium Calculation of Supercritical CO2 and H2O at High Temperatures and Pressures

There are numerous models available to compute phase equilibrium composition of supercritical CO₂ and H₂O at high temperatures and pressures. In this paper a different approach is proposed where liquid state models (LSM) are used following liquid–liquid equilibrium (LLE) flash calculation in order to obtain phase compositions (solubility of CO₂ in the H₂O rich phase and that of H₂O in the CO₂ rich phase). Four LSM (two two-parameter models UNIQUAC and LSG, and two three-parameter models NRTL and GEM-RS) are investigated. The original forms of these models are inappropriate to represent the literature values; the binary interaction parameters are related with both pressure and temperature. These modified versions are suitable to generate phase composition values within 2–7 % deviation. Further investigations show that the LLE calculation is more time efficient than vapor–liquid equilibrium computation, meaning our approach can save computational expense for the numerical simulation of CO₂ flows in a reservoir. Comparison of the time efficiency of these LSM models with respect to other equations of state is given.     

Vapor—liquid equilibria of the binary mixtures methyl chloride — methanol and dimethyl ether — methyl chloride and of the ternary mixture dimethyl ether — methyl chloride — methanol

Vapor Liquid Equilibria in mixtures of dimethyl ether, methyl chloride and methanol were investigated in a static equilibrium apparatus for temperatures 250 K < T <350 K and pressures up to 1 MPa. Temperature, pressure and the composition of the liquid and the vapor phase were determined.The consistency of the binary experimental data was checked and parameters of several g^E-models were fitted. The binary parameters were used to predict the ternary VLE and the calculated results were compared with the experimental data.     

Elements of the topology of the region of the existence of the metastable states of a two-component vapor

Entire regions of the metastable states for binary and single-component systems were constructed. It was established that the regions include temperature intervals from absolute zero to critical temperatures, and from vapor—condensate equilibrium to the conditions of spinodal decomposition of supersaturated vapor in the system. Algorithms for determining the regions of metastable states are presented. The data obtained on their basis are noted to coincide qualitatively with known results. Correlations found earlier are employed to calculate the critical pressures and temperatures for the binary systems in the study.     

4-(Trimethylsilyl)morpholine: synthesis,characterization, and prospects of use in film deposition processes

4-(Trimethylsilyl)morpholine (TMSM) was synthesized and shown to be applicable as a precursor for plasma-enhanced chemical vapor deposition of films. The temperature depen dence of the saturated vapor pressure of TMSM was determined by tensimetry and the thermodynamic characteristics of its evaporation were calculated. Thermodynamic modeling (calculation of the "equilibrium" compositions of the condensed and gas phases) was carried out for broad ranges of temperatures (300—1200 K), pressures (10^–2—10 Torr), and input gas (inert gas, H₂, NH₃) to precursor flow ratios (0—50). The calculation results were used to predict the composition of deposited condensed products occurring in equilibrium with the gas phase depending on the composition of the initial gas mixture and reaction conditions.     

Isobaric vapor–liquid equilibria of the binary system maleic anhydride and di-isobutyl hexahydrophthalate at 2.67, 5.33 and 8.00 kPa

Isobaric vapor–liquid equilibrium (VLE) data for the binary system maleic anhydride (MAN) + di-isobutyl hexahydrophthalate (DIBE) at 2.67, 5.33 and 8.00 kPa were measured with a modified ebulliometer. Also, saturated vapor pressures of pure DIBE were measured and Antoine constants were obtained. These data were used to calculate equilibrium vapor and liquid compositions for this binary system using the NRTL model. Prediction of the VLE was done with the universal quasi-chemical functional-group activity coefficients (UNIFAC) model. The predicted results generally agree with those from experiment.     

Application of correlation-gas chromatography to evaluate the vaporization enthalpy of a component in an equilibrium mixture

The vaporization enthalpies and vapor pressures of acetoin, ethyl 3-hydroxybutyrate and ethyl 3-hydroxyhexanoate, found in a variety of foods and flavors, are evaluated at T = 298.15 K using correlation-gas chromatography; values of (48.7 ± 0.4), (55.9 ± 0.6) and (61.9 ± 0.6) kJ mol⁻¹, respectively, were obtained. These values are in good agreement with estimated values. Vapor pressures of the standards as a function of temperature were also used to calculate vapor pressures of the target compounds and all resulting data were fit to second order polynomials. These polynomials were then used to predict boiling temperatures of both standards and target substances. Agreement with experimental boiling temperatures was generally within 10 K suggesting that vapor pressures are accurate to within a factor of two. Acetoin exists as an equilibrium mixture of monomer and dimer. This report provides an example of the utility of using correlation-gas chromatography to obtain thermochemical data on an impure material.     

氯仿,乙醇,苯有关二元体系加压相平衡研究

氯仿、乙醇、苯有关二元体系加压相平衡研究马忠明，陈庚华，王琦，严新焕，韩世钧，余淑娴（浙江大学化学系，杭州，３１００２７）（江西大学化学系）关键词加压汽液平衡，醇烃体系，氯仿，乙醇，苯醇是极性分子，烃是非极性或弱极性分子，醇与醇、烃与烃分子及醇与烃分...     

Phase compositions and saturated densities for the binary systems of carbon dioxide with ethanol and dichloromethane

The compositions and densities of the liquid and vapor phases of two binary systems at equilibrium were measured on a new experimental apparatus over a range of temperatures and pressures. The studied systems are: CO₂–ethanol at 313.2 and 328.2 K; CO₂–dichloromethane at 308.2, 318.2 and 328.2 K and for pressures ranging from ambient up to ca. 9 MPa. Some of our measurements are critically compared with corresponding literature values. These measurements are ideally suited for testing equation-of-state models. The recently developed quasi-chemical hydrogen-bonding (QCHB) model was used for correlating the experimental data. A satisfactory agreement was obtained between experimental and calculated phase compositions and saturated densities.     

Thermodynamic properties of new heat pump working pairs: 1,3-Dimethylimidazolium dimethylphosphate and water,ethanol and methanol

Ionic liquid 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]) + water/ethanol/methanol mixtures exhibit properties which render them suitable as candidates for working pairs in industrial applications of absorption heat pumps or chillers. In this paper, the thermodynamic properties including vapor pressure, density, viscosity, heat capacity as well as excess enthalpy of these binary systems were measured at various temperatures with different ionic liquid concentrations. The thermodynamic properties were correlated by different equations, respectively. The correlated values were significantly consistent with the experimental ones. In conclusion, the vapor–liquid equilibrium (VLE) data indicated that the vapor pressures of the three solvents in [MMIM][DMP] displayed a considerable negative deviation from Raoult's law, and the excess enthalpies of the three binary systems are negative. These characteristics are necessary and important for an absorption working pair.     

Estimation of solid vapor pressures of pure compounds at different temperatures using a multilayer network with particle swarm algorithm

Solid vapor pressures (P^S) of pure compounds have been estimated at several temperatures using a hybrid model that includes an artificial neural network with particle swarm optimization and a group contribution method. A total of 700 data points of solid vapor pressure versus temperature, corresponding to 70 substances, have been used to train the neural network developed using Matlab. The following properties were considered as input parameters: 36 structural groups, molecular mass, dipole moment, temperature and pressure in the triple point (upper limit of the sublimation curve), and the limiting value P^S → 0 as T → 0 (lower limit of the sublimation curve). Then, the solid vapor pressures of 28 other solids (280 data points) have been predicted and results compared to experimental data from the literature. The study shows that the proposed method represents an excellent alternative for the prediction of solid vapor pressures from the knowledge of some other available properties and from the structure of the molecule.