Nitta-Chao Model Research Articles

Experimental and Nitta–Chao model prediction of high pressure density of p-xylene with dialkyl carbonates or n-alkanes

New data of high pressure density have been reported for p-xylene pure component and its binary mixtures with dimethyl carbonate, diethyl carbonate, n-octane and n-decane at (288.15, 298.15 and 308.15)K and (0.1, 5, 10, 20, 30 and 40)MPa and they have been compared with those available in the literature. The high pressure density has been correlated and predicted using a modified Tait equation and Nitta Chao group contribution model respectively. The derived thermophysical properties such as isothermal compressibility (κT), isobaric thermal expansivity (αP) and internal pressure (π) have been also calculated.

Volumetric properties of (dialkyl carbonate + n-alkane) mixtures at high pressures: Experimental measurement and Nitta–Chao model prediction

The present work reports valuable experimental high-pressure density data for dimethyl carbonate, diethyl carbonate, n-octane, n-decane pure components and their binary mixtures (dialkyl carbonate+n-alkane) at temperatures between (288.15 and 308.15)K and pressures between (0.1 and 40)MPa. The experimental density values were compared with experimental information available in the literature. While the volumetric properties for (dimethyl carbonate+n-alkane) were reported in many works, the (diethyl carbonate+n-alkane) were less studied. The purpose of this study is to extend the available experimental information about the thermophysical behavior of this kind of mixtures, which is useful in the fuel field. The experimental density data were correlated using a modified Tait equation and were predicted by Nitta–Chao group contribution model.

Analysis of the thermodynamic properties of (1-chloroalkane + 1-alkanol) mixtures using the Nitta–Chao group contribution model

The interaction parameters between group chloro (–Cl) and hydroxyl (–OH) for the group contribution model of Nitta et al. 1977 (Nitta–Chao model) have been estimated with the use of a data base of experimental thermodynamic properties. The results obtained by the Nitta–Chao model with these new parameters were compared with predictions by other models such as UNIFAC model (versions of Dang and Tassios 1986, Larsen et al. 1987 and Gmehling et al. 1993).

Prediction of the pressure dependence on the thermodynamic properties of dialkyl carbonate + alkane mixtures using Nitta–Chao model

In this work we analyze the ability of the Nitta–Chao model for the prediction of the pressure dependence of different thermodynamic properties, such as density, isobaric thermal expansivity coefficient, isothermal compressibility coefficient and internal pressure of the pure components (dimethyl carbonate and diethyl carbonate). We also study phase equilibria, pVTx values and their derived coefficients, internal pressures, excess molar volumes, excess molar enthalpies and excess Gibbs energies of dialkyl carbonate+ n-alkane binary mixtures. For this purpose we have used the characteristic parameters calculated in a previous paper for dialkyl carbonate+ n-alkane systems with a database which contained thermodynamic properties values at atmospheric pressure or near to the atmospheric pressure. The Nitta–Chao model predicts the different thermodynamic properties fairly well in the ranges of temperature 278.15 K<T<353.15 K and of pressure 0.1 MPa<p<60 MPa. It is important to point out that both ranges are much broader than those of the experimental values of the thermodynamic properties database used to determine the parameters.

Estimation of carbonate–alcohol interaction parameters for Nitta–Chao group contribution model: application of a Genetic Algorithm

In this work, the characteristic parameters for the interaction of carbonate–hydroxyl pair for the Nitta–Chao model have been calculated using an updated data base of vapour–liquid equilibria, activity coefficients at infinite dilution, excess molar enthalpies and excess molar volumes of carbonate+1-alkanol binary mixtures. In the process of optimisation of the interaction parameters a Genetic Algorithm (GA) has been used.

Density, speed of sound and refractive index of (n-hexane + cyclohexane + 1-hexanol) atT = 298.15 K

Densities, speeds of sound and refractive indices have been measured for (n -hexane + cyclohexane + 1-hexanol) and its corresponding binaries atT= 298.15 K. In addition, ideal isentropic compressibilities were calculated from the speeds of sound, densities, and literature heat capacities and cubic expansion coefficients. The excess molar volumes and excess isentropic compressibilities, and deviations of the speed of sound and refractive index are correlated by polynomials and discussed.The Nitta–Chao model was used to estimate binary and ternary excess molar volumes, and several empirical equations were also used to calculate the excess and deviation properties.

Density, speed of sound, refractive index and dielectric permittivity of (diethyl carbonate + n -decane) at several temperatures

Density, speed of sound and refractive index values of (diethyl carbonate +n -decane), were measured at the temperatures (288.15, 293.15, 298.15, and 308.15) K and atmospheric pressure. In addition, dielectric permittivities have been measured for the same mixture and at the same temperatures except at T= 293.15 K. Excess molar volumes, changes of isentropic compressibility on mixing, changes of refractive index on mixing and changes of dielectric permittivity on mixing were computed from the experimental data. The excess molar volumes were compared with predictions from the Nitta–Chao model.

Modelling thermodynamic properties of iodoalkane + alkane systems using group contribution models

The experimental data available in the literature for the binary systems 1-iodoalkane and α,ω-diiodoalkane with alkanes are used to determine the interaction parameters of the iodine and methyl or methylene groups of the Nitta–Chao equation-of-state group contribution model and of three versions of the UNIFAC model due to Tassios et al., Larsen et al. and Gmehling et al. The results for the thermodynamic properties obtained using the new parameters of the three versions of the UNIFAC and Nitta–Chao models are compared with those of the DISQUAC model. Liquid–liquid equilibria data of α,ω-diiodoalkane + alkane mixtures were used to check the obtained interaction parameters. An analysis of the dispersive and non-dispersive interactions is presented with the estimation of the changes of the mean numbers of contacts between the iodine, methyl and methylene groups during the mixing process.

Analysis of the molecular interactions of organic anhydride+alkane binary mixtures using the Nitta–Chao model

The Nitta–Chao EOS group-contribution model, based on cell theory, is used to study the interactions of the organic anhydride+ n-alkane binary mixtures. A database of excess enthalpies, excess Gibbs energies and excess volumes for this kind of mixtures, together with molar volumes and vaporization enthalpies of pure organic anhydrides, were used to calculate the characteristic parameters of the Nitta–Chao group-contribution model. In order to enlarge the database, the excess molar volumes at 298.15 K for the binary mixtures of pentanoic and hexanoic acid anhydrides with an n-alkane are reported. An analysis of the interactions is presented with the estimation of the changes of the mean numbers of contacts between the different groups during the mixing process. The influence of the dispersive and non-dispersive interaction energy parameters on the excess volumes and excess enthalpies is also presented. The model consistently describes the experimental data of organic anhydride+ n-alkane mixtures, i.e. the excess volumes increase when the anhydride chain length decreases and when alkane chain length increases. The symmetry of the V E( x) curves and the sign and magnitude of the excess volumes are strongly dependent on the lengths of the alkane and of the organic anhydride.

Thermodynamic properties of (a propyl ester + ann-alkane). XII. Excess molar enthalpies and excess molar volumes for {xCH3(CH2)u − 1COO(CH2)2CH3 + (1 − x)CH3(CH2)2v + 1CH3} withu = (1to 3), andv = (1to 7)

Excess molar enthalpiesHmEand excess molar volumesVmEwere determined at the temperature 298.15 K for 21 binary mixtures of three propyl esters (ethanoate, propanoate, and butanoate) and seven oddn-alkanes (pentane to heptadecane). All the mixtures exhibited endothermic enthalpies which decreased quasi-exponentially with the ester chain length in the same proportion as their dipole effects. The variations of the excess molar volumes for these mixtures followed a similar decreasing trend, with contractions observed in the systems consisting of high molar mass esters and lowestn-alkanes. These effects have been interpreted on the basis of molecular interactions. The UNIFAC, DISQUAC, and Nitta–Chao models were used to estimate the thermodynamic properties considered, and yielded acceptable results.

Excess molar volumes of ternary mixtures di- n-butyl ether+1-pentanol+ n-dodecane at 298.15 K

Excess molar volumes of { x 1di- n-butyl ether+ x 21-pentanol+(1− x 1− x 2) n-dodecane} and the binary mixtures { xdi- n-butyl ether+(1− x) n-dodecane} and { x1-pentanol+(1− x) n-dodecane} were measured at 298.15 K using an Anton Paar DMA 60/602 densimeter. All the experimental values were compared with the results obtained by empirical expressions for estimating ternary properties from binary results. Variable-degree polynomials have been fitted to the results. The experimental excess molar volumes were compared with the results obtained with the Nitta–Chao model.

Estimation of parameters of Nitta–Chao model for ester+1-alkanol mixtures

An updated database with experimental values on vapor–liquid equilibria, activity coefficient at infinite dilution, enthalpies of mixing and excess molar volumes of alkyl alkanoate+1-alkanol binary systems was used to redetermine structure and interaction parameters of the Nitta–Chao model. We have compared the theoretical results obtained with the Nitta–Chao model and our parameters with the experimental data. The percentual mean deviations with the parameters calculated in this work are quite good for all properties studied. We have used the same database to analyse the quality of the predictions of three versions of UNIFAC model for this type of mixtures.

Viscosities and Densities for the 1-Propanol + n-Heptane System at Several Temperatures

Viscosities and densities have been measured for 1-propanol + n-heptane at 20, 25, 30, and 35°C and atmospheric pressure. Kinematic viscosities were determined using a capillary viscosimeter; densities were measured using vibrating-tube densimetry. The viscosity deviations were evaluated. Viscosity results were fitted to the equations of Grunberg–Nissan, McAllister, Auslander, and Teja. The experimental excess molar volumes were compared with the results obtained with the Nitta–Chao model.

Application of different group contribution models and empirical methods to excess enthalpies of ternary mixtures

Studies were previously made of the excess molar enthalpies, HmE, at 298.15 K and normal atmospheric pressure of the ternary mixtures (ethyl propanoate or 3-pentanone) + (n-hexane) + (n-decane, n-dodecane or n-tetradecane) and (1-propanol) + (3-pentanone) + (n-hexane, n-heptane, n-octane, 1-hexanol or 1-heptanol). In the present work, experimental values of HmE were correlated through use of the Cibulka and Nagata equations, and a new correlation equation is proposed. Experimental data were compared with the predictions of the UNIFAC I (version of Tassios), UNIFAC II (version of Larsen) and Nitta-Chao group contribution models. HmE values were used to test several empirical predictive methods, both symmetric (Kohler, Jacob-Fitzner, Colinet and Knobeloch-Schwartz), and asymmetric (Tsao-Smith, Toop, Scatchard, Hillert and Mathieson-Tynne).

Experimental excess volumes of organic carbonate+alkane systems. Estimation of the parameters of the Nitta–Chao model for this kind of binary mixture

Excess volumes at 298.15 K and atmospheric pressure of some organic carbonate+alkane binary systems have been measured using an Anton Paar 602 HP densimeter. For the first time, published data on excess enthalpies, excess volumes, excess Gibbs energies of the above-mentioned binary systems together with the vaporisation enthalpies and the molar volumes of the pure organic carbonates, were used to estimate the interaction parameters between the carbonate group O–CO–O and the methyl and methylene groups, CH3, CH2, respectively. The mean deviations between experimental and theoretical values were smaller than 6% for all the properties. We have also compared our results with those obtained by Garcia etal. with the Original, Tassios etal., Larsen etal. and Gmehling etal. versions of the UNIFAC model and with those obtained by Kehiaian etal. using the DISQUAC model.

Ability of the Nitta-Chao model for the prediction of pressure and temperature dependence of the volumetric properties of n-alkane + 1-alkanol systems

Volumetric behaviour of n-alkane + 1-alkanol mixtures in a wide range of temperatures and pressures was examined on the basis of the Nitta-Chao model. Literature data of experimental densities in a temperature range from 298.15 to 373.15 K and pressures up to 40 MPa were selected in order to test the model predictions for the following quantities: excess molar volumes ν E and isothermal compressibilities κ T. ( ∂ν E ∂T ) p and ( (∂h E ∂p ) T obtained from density data were compared with those predicted with the Nitta-Chao model.

Estimation of parameters of Nitta-Chao model for linear monoether + 1-alkanol mixtures

We have estimated the interaction parameters for ether and hydroxyl groups using an extensive experimental database of vapour-liquid equilibria, activity coefficients at infinite dilution, enthalpies of mixing and volumes of mixing of linear monoether + 1-alkanol binary systems. The theoretical results obtained with the parameters proposed are significantly closer to the experimental values than those determined with the parameters of Eckart et al. In addition, the values of thermodynamic properties obtained by the Nitta-Chao model with both set of parameters have been compared with the predictions resulting from other models, such as the DISQUAC model and the UNIFAC model, in its original version and those of Dang and Tassios, Larsen et al. (UNIFAC-Lingby) and Gmehling et al. (UNIFAC-Dortmund).

Quantum mechanical characterisation of functional groups for molecular solution theories using Bader fragments

A method for characterising functional groups in organic molecules for use in group contribution molecular theories for liquid mixtures is proposed. It uses a quantum mechanical criterion for electronic charge distribution based on the theory of atoms in molecules developed by Bader, the distribution being established from ab initio quantum mechanical computations. The method was developed by studying the main conformers of linear alkanes from ethane to hexane, in addition to the following linear esters; methyl, ethyl, propyl and butyl formate; methyl, ethyl and propyl acetate; methyl, ethyl and propyl propanoate; and methyl and ethyl butanoate. The proposed criterion allows one not only to identify functional groups but also to account for proximity effects. It was validated by using the Nitta–Chao model to estimate thermodynamic properties of the pure liquids studied (esters and alkanes) and their mixtures. The results were significantly better than those provided by earlier calculations for ester–alkane systems.

Analysis of Excess Molar Volumes of the Ternary Systems Containing a Propyl Alkanoate and Two Alkanes with Some Predictive Methods

Abstract Excess molar volumes at 298.15 K of the ternary mixtures (propyl ethanoate + n-heptane + n-decane), (propyl propanoate + n-heptane + n-decane) and (propyl butanoate + n-heptane + n-decane) were determined using a DMA 60/602 Anton Paar densimeter. All the experimental values were compared with the results obtained with empirical expressions for estimating ternary properties from binary data and with the Nitta-Chao group-contribution model. For these ternary mixtures the same behaviour that had been observed in ester + n-alkane binary systems was found: excess volumes decrease when the ester length increases.

Estimation of the Nitta-Chao Parameters for the ether-group. Ether + n-alkane mixtures

In this work we have estimated the structural and interactional parameters of the ether- group for the group-contribution model of Nitta-Chao using a extensive experimental database of thermodynamic properties of ethers (monoethers, polyethers and acetals) and ether + n-alkane and ether + ether mixtures. The results obtained by Nitta-Chao model with this parameters get closer to the experimental values than those obtained with parameters of Eckart et al. (1986). The thermodynamic properties obtained by the Nitta-Chao model with old and new parameters were compared to predictions by other models such as Flory (1965) theory, DISQUAC (Kehiaian, 1977) model and UNIFAC model (versions of Dang and Tassios, 1986, and Larsen et al., 1987).