Isobaric Expansion Research Articles

Liquid phase PVTx properties of binary mixtures of (water + ethylene glycol) in the range from 278.15 to 323.15 K and from 0.1 to 100 MPa. II. Molar isothermal compressions, molar isobaric expansions, thermal pressure coefficients and internal pressure

Molar isothermal compressions, molar isobaric expansions, molar coefficients of thermal pressure, and internal pressures of {water (1)+ethylene glycol (2)} mixture over the whole concentration range, as well as partial molar isothermal compressions and partial isobaric expansions of water in ethylene glycol and of ethylene glycol in water at infinite dilution were calculated at pressures from 0.1 to 100MPa and at temperatures from 278.15 to 323.15K. It was revealed that concentration dependences of molar isothermal compressions KT,m, molar isobaric expansions EP,m, and thermal pressure coefficients, β, on ethylene glycol molar fraction had extremes. Temperature and baric dependences of internal pressure of the mixture were almost linear, and coefficients of these dependences at low ethylene glycol concentrations differed from those coefficients for water, ethylene glycol, and their mixtures with high diol content. Analysis of the volume characteristics obtained confirmed both hydrophilic and hydrophobic ethylene glycol nature.

Volumetric Properties of the {x 1[C4mim][MeSO4] + (1 − x 1)MeOH} System at Temperatures from (283.15 to 333.15) K and Pressures from (0.1 to 35) MPa

Densities of pure 1-butyl-3-methylimidazolium methylsulfate, [C4mim][MeSO4], and its mixtures with methanol have been measured. Measurements were made with an accuracy of ±0.2 kg·m−3, using a vibrating-tube densimeter, over the temperature and pressure ranges (283.15–333.15) K and (0.1–35) MPa, respectively. The experimental densities for the pure ionic liquid and alcohol have been correlated by the Tait equation. The results for the {x 1[C4mim][MeSO4] + (1 − x 1)MeOH} system have been correlated by a van Laar equation involving parameters that are dependent on temperature and pressure. Excess volumes have been obtained directly from the experimental densities, while isobaric expansivities, isothermal compressibilities, and related excess properties were calculated from the correlation equation. Exceptionally strong pressure and temperature influences on these properties were observed.Electronic supplementary materialThe online version of this article (doi:10.1007/s10953-013-0016-8) contains supplementary material, which is available to authorized users.

Ultrasound speeds and molar isentropic compressions of (3-ethoxypropane-1-amine + water) mixtures from T = (283.15 to 303.15) K

Alkoxyamines containing two hydrophilic groups with great affinity to water are multipurpose compounds with important applications, either on theoretical or practical grounds. The thermodynamic characterization of aqueous mixtures of these compounds is scant. Ultrasound speed measurements have been made in 53 mixtures of the aqueous ethoxypropane-1-amine binary system, across the entire composition range and temperatures between T=(283.15 and 303.15)K, at atmospheric pressure. By combining ultrasound speed and density data, values of the isentropic compressibility were derived. Excess molar isentropic compressions were estimated and analytically fitted to Redlich–Kister polynomial equations. Excess partial molar quantities were then calculated including their limiting values, which were obtained from the Redlich–Kister fitting coefficients. The temperature dependences of limiting partial molar isentropic compressions and isobaric expansions were also scrutinized. Compressibility changes associated with different patterns of aggregation and hydration over the whole composition range are identified.

Effect of solvent on the volumetric behavior of N,N′-salicylidenephenyl diamine (Salophen) Schiff base at different temperatures (288.15–318.15) K

Densities of binary mixtures containing N,N′-salicylidenephenyl diamine (Salophen)+organic solvents {dimethylsulfoxide (DMSO), N,N-dimethylacetamide (DMA), 1,4-dioxacyclohexane (1,4-dioxane), and oxolane (THF)} have been measured at 10K intervals from 288.15K to 318.15K. Using these data, apparent molar volumes (Vϕ), standard partial molar volumes (Vϕ0), standard partial molar isobaric expansivity (Eϕ0), Hepler's constant (∂2Vϕ0/∂T2)p, and isobaric thermal expansion coefficient (α) have been calculated for all the mixtures. The values of interaction volumes (Vint), and cavity volumes (Vcav) have also been estimated using the scaled particle theory [20]. The results show that Salophen in the studied organic solvents predominantly acts as a structure-breaker.

Volumetric Properties of Propane, n-Octane, and Their Binary Mixtures at High Pressures

Density, isothermal compressibility, isobaric expansivity, thermal pressure coefficient, and excess volumes for binary mixtures of propane + n-octane are reported over a wide range of temperatures (from 320 to 440 K), and pressures (up to 400 bar) for mixture compositions with 0, 20.4, 42.4, 58.9, 79.7, and 100 wt % propane. Densities were determined using a fully computerized variable-volume view-cell system. A motorized pressure generator is used to bring about changes in the position of a movable piston in the cell at controlled and adjustable rates thereby bringing about changes in the internal volume and thus pressure. A long stroke-length linear variable differential transformer is used to continually monitor the position of the piston and thus the cell volume in real-time. Knowing the initial loading of the cell and the cell volume at any moment as pressure is altered permits generation of continuous density profiles along pressure scans in increasing (compression) or decreasing (decompression) dir...

Thermodynamic properties for liquid mercury using GMA equation of state

The important known regularities and thermodynamic properties of liquid mercury have been studied based on the average potential energy. Recognised regularities, the linearity of Zeno contour, bulk modulus and secant bulk modulus as functions of temperature, isochors of pressure versus temperature and near linearity of the inverse isobaric expansion coefficient have been investigated, all evaluated using the Goharshadi–Morsali–Abbaspour equation of state. The validity of the equation of state in predicting thermophysical properties is confirmed by a statistical parameter, absolute average deviation, with a maximum value of 0.41, showing excellent agreement with the experiment at temperatures between 293.15 and 323.15 K from low to high pressures.

Densities, ultrasonic speeds, viscosities and excess properties of binary mixtures of methyl methacrylate with N,N-dimethylformamide and N,N-dimethylacetamide at different temperatures

The densities, ρ, ultrasonic speeds, u and viscosities, η of binary mixtures of methyl methacrylate (MMA) with N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA), including those of pure liquids, over the entire composition range were measured at temperatures (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15)K and atmospheric pressure. From the experimental results, the excess molar volume, VmE, and excess isentropic compressibility, κsE, excess isobaric coefficient of thermal expansion, αpE and excess molar isobaric expansion, Ep,mE were calculated. The excess partial molar volume, V¯m,1E and V¯m,2E and excess partial molar isentropic compressibility, K¯s,m,1E and K¯s,m,2E over the whole composition range; and partial molar volume, V¯m,1° and V¯m,2°, partial molar isentropic compressibility, K¯s,m,1° and K¯s,m,2°, excess partial molar volume, V¯m,1°E and V¯m,2°E, excess partial molar isentropic compressibility, K¯s,m,1°E and K¯s,m,2°E at infinite dilution, and excess partial molar isobaric expansion, E¯p,m,1E and E¯p,m,2E over the whole composition range have also been calculated. The variations of these parameters with composition and temperature of the mixtures are discussed in terms of molecular interaction in these mixtures. It is observed that the MMA-DMF/DMA interactions in these mixtures follow the order: DMF<DMA. Further, the viscosities of these binary mixtures were correlated theoretically by using various empirical and semi-empirical models and the results were compared with the experimental findings.

Quantum Heat Engines; Multiple-State 1D Box System

We evaluate quantum Otto, Diesel and Brayton cycles employing multiple-state 1D box system instead of ideal gas filled cylinder. The work and heat are extracted using the change in the expectation of Hamiltonian of the system which leads to the first law of thermodynamics to quantum system. The first law makes available to redefine the force which is in fact not well defined in a quantum mechanical system and then it is applied to define the quantum version of thermodynamic processes, i.e. isobaric, isovolume and adiabatic. As the results, the efficiency of quantum Otto engine depends only on the compression ratio and will be higher than the efficiency of quantum Diesel which can decrease by the widening of expansion under isobaric process. The efficiency of quantum Brayton engine may reach maximum on certain combination between the wide of box under isobaric expansion and compression, under certain conditions. The amount of levels participated in the quantum heat engine system will potentially reduce the performance of the quantum heat cycles consisting isobaric process, but it can be resisted using isobaric process controller.

Experimental and VTPR-predicted volumetric properties of branched hexanes

Densities of the four branched isomeric hexanes: 2,2,-dimethylbutane, 2,3-dimethylbutane, 2-methylpentane and 3-methylpentane have been measured using a high-pressure, high-temperature vibrating tube densimeter system over a temperature range from 283.15 to 328.15K and a pressure range from 0.1 to 65.0MPa. The experimental densities have been satisfactorily correlated with the temperature and pressure using the Tait equation. Furthermore, using this equation and thermodynamic relations, isobaric expansibilities and isothermal compressibilities have been calculated. Finally, the volume translated Peng–Robinson group contribution equation of state (VTPR model) has been used to predict the densities of the compounds studied in the whole temperature and pressure ranges, the deviations between experimental and calculated densities in terms of relative root-mean square deviations are comprised between 0.40 and 0.55% for the liquids studied, so the predictions can be considered as satisfactory.

The pρT behaviour of the lactate family

The densities of methyl lactate, ethyl lactate and butyl lactate have been measured using a high-pressure, high-temperature vibrating tube densimeter system over a temperature range from T=(283.15 to 338.15)K and a pressure range from p=(0.1 to 60.0)MPa. The experimental densities have been satisfactorily correlated with temperature and pressure using the TRIDEN equation. Finally, from the experimental densities, properties such as isobaric expansibility and isothermal compressibility have been calculated.

Studies on the interactions of diglycine and triglycine with polyethylene glycol 400 in aqueous solutions by density and ultrasound speed measurements

Density and ultrasound speed were measured accurately for diglycine+water, triglycine+water, diglycine+water-polyethylene glycol 400 (PEG400) and triglycine+water-PEG400 solutions at T=(293.15, 298.15, 303.15 and 308.15)K. The results were used in evaluating thermodynamic properties as apparent molar volumes (VØ) and apparent molar isentropic compressions (KSΦ) of diglycine and triglycine in water and in PEG400 solutions. Infinite dilution values of these parameters, VoØ, and KoSΦ, were obtained from their plots as a function of molality by extrapolation and have been utilized in obtaining transfer volumes and transfer compressions at infinite dilution. All transfer volumes and transfer compressions were found to increase with increasing molality of PEG400. Apparent molar isobaric expansions were derived from the temperature dependence of VØ values at infinite dilution and at finite concentrations. All the results were interpreted in terms of solute (diglycine or triglycine) and co-solute (PEG400) and solvent (H2O) interactions.

Volumetric properties of the ionic liquids: [C6mim][MeSO4], [C6mim][EtSO4], [C4mim][EtSO4] and their mixtures with methanol or ethanol

Densities of pure ionic liquids, 1-hexyl-3-methylimidazolium methylsulfate [C6mim][MeSO4], 1-hexyl-3-methylimidazolium ethylsulfate, [C6mim][EtSO4], 1-butyl-3-methylimidazolium ethylsulfate [C4mim][EtSO4] and their mixtures with either methanol or ethanol, were measured at temperatures T/K=(283.15, 298.15, 313.15, 328.15) at ambient pressure. The excess volumes VE were correlated by the van Laar equation with the temperature-dependent parameters. Isobaric expansivity and excess isobaric expansivity were described as functions of temperature and composition. The negative deviations from ideal mixing were observed for excess volume VE and the excess isobaric expansivity αE.

Liquid phase PVTx properties of (water + tert-butanol) binary mixtures at temperatures from 278.15 to 323.15 K and pressures from 0.1 to 100 MPa. II. Molar isothermal compressions, molar isobaric expansions, molar thermal pressure coefficients, and internal pressure

Molar isothermal compressions, molar isobaric expansions, molar coefficients of thermal pressure, and internal pressure were calculated over the whole concentration range of {water (1)+tert-butanol (2)} mixture at pressures from 0.1 to 100MPa and temperatures from 278.15 to 323.15K. It was revealed that the extremes, observed on concentration dependences of molar isothermal compression KT,m and molar isobaric expansion EP,m of the mixture, became more pronounced with pressure growth and temperature lowering. Values of molar thermal pressure coefficients of the mixture sharply rose at compositions with small TBA mole fraction and then decreased practically linearly with the alcohol content increasing. Temperature and pressure dependences of the mixture internal pressure were almost linear, and at low TBA concentrations changed significantly from the dependences of water, tert-butanol and their mixtures at large alcohol content.

Densities of a deep eutectic solvent based on choline chloride and glycerol and its aqueous mixtures at elevated pressures

Deep eutectic solvents are cheap and biodegradable alternatives to conventional ionic liquids and volatile organic solvents. In this work, we present new measurements on the densities of the deep eutectic solvent choline chloride:glycerol (GLY) and its aqueous mixtures in the temperature range (298.15–323.15)K and pressures up to 50MPa. The density was measured using a vibrating-tube density meter and the experimental uncertainty was estimated to be ±0.1%. Density data were used to derive other properties such as isothermal compressibility, isobaric expansivity, and excess molar volume. The excess molar volumes of the mixtures of GLY (1)+H2O (2) were investigated and an empirical equation was used to represent their dependence on temperature, pressure, and composition. The density data at elevated pressures were correlated with the temperature, pressure, and composition by a Tait-type equation.

Density and Viscosity of Binary Mixtures of Thiocyanate Ionic Liquids + Water as a Function of Temperature

Densities and viscosities have been determined for binary mixtures of the ionic liquids (ILs) 1-butyl-3-methylimidazolium thiocyanate [BMIM][SCN], or 1-butyl-4-methylpyridinium thiocyanate [BMPy][SCN], or 1-butyl-1-methylpyrrolidinium thiocyanate [BMPYR][SCN], or 1-butyl-1-methylpiperidinium thiocyanate [BMPIP][SCN] with water over wide range of temperatures (298.15–348.15) K and ambient pressure. The thermal properties of [BMPy][SCN], i.e. glass transition temperature and the heat capacity at glass transition, have been measured using a differential scanning microcalorimetry, DSC. The decomposition of [BMPy][SCN] was detected. The density and viscosity correlations for these systems have been made using an empirical second-order polynomial and by the Vogel–Fulcher–Tammann equation, respectively. The concentration dependences have been described by polynomials. The excess molar volumes and deviations in viscosity have been calculated from the experimental values and were correlated by Redlich–Kister polynomial expansions. The variations of these parameters, with compositions of the mixtures and temperature, have been discussed in terms of molecular interactions. A qualitative analysis of the trend of properties with composition and temperature was performed. Further, the excess partial molar volumes, V_{1}^{mathrm{E}} and V_{2}^{mathrm{E}}, were calculated and discussed. The isobaric expansivities (coefficient of thermal expansion), α, and the excess isobaric expansivities, α E, were determined for four ILs and their mixtures with water. The results indicate that the interactions of thiocyanate ILs with water is not as strong as with alcohols, which is shown by the positive/slightly negative excess molar volumes in these binary systems.Electronic Supplementary MaterialThe online version of this article (doi:10.1007/s10953-012-9875-7) contains supplementary material, which is available to authorized users.

Densimetric Studies of Binary Solutions Involving H2O or D2O as a Solute in Dimethylsulfoxide at Temperatures from (293.15 to 328.15) K and Atmospheric Pressure

Densities of H2O and D2O solutions in dimethylsulfoxide, with solute mole fractions ranging up to 0.037, were measured with an uncertainty of 1.5×10−5 g⋅cm−3 at eight temperatures between 293.15 and 328.15 K (with a step of 5 K) under atmospheric pressure using a sealed vibrating-tube densimeter. Apparent molar volumes and isobaric expansibilities (down to infinite dilution) of water isotopologues, as well as excess molar volumes of both solutes and solutions as a whole, were calculated. The temperature-dependent behavior of H2O→D2O solute isotope effects on the studied molar volumetric characteristics was interpreted by taking into account the structural and related interaction peculiarities of the dissolving medium in question.

High-pressure volumetric properties of choline chloride–ethylene glycol based deep eutectic solvent and its mixtures with water

The densities of the deep eutectic solvent (DES) based on choline chloride and ethylene glycol (Ethaline) and its mixtures with water were measured from 298.15K to 323.15K over an extended pressure range (0.1–50)MPa. Other important properties such as isothermal compressibility and isobaric expansivity were derived for the pure system using the experimental data. The high-pressure densities were accurately correlated to the temperature, pressure and composition using a Tait-type equation. For the binary mixtures of Ethaline (1)+H2O (2), the excess molar volumes were investigated and represented as a function of temperature and composition by a Redlich–Kister-type equation. Results indicated that the correlations proposed in this work can be used to accurately predict the densities of the studied systems as functions of temperature, pressure and composition.

A new equation of state for molten alkali metal alloys

A new proposed equation of state (EoS) for pure liquid alkali metals has been extended to predict the volumetric and thermodynamic properties of alkali metal alloys at different temperatures, pressures, and compositions. The new equation which is valid over the whole liquid range is based on a suggested potential function and the interactions of nearest neighbors are according to the characteristics of the soft repulsive interaction in dense and large attractive interaction in expanded liquid alkali metals. The composition dependencies of the parameters of the equation of state are assumed as quadratic functions of mole fraction considering the mean geometry approximation “MGA”. In this paper, the calculated results of liquid density and other thermodynamic properties such as isobaric expansion coefficient, αP, isothermal compressibility, κT, and internal pressure, Pi, of binary molten alloys of Na–K and Cs–K from the freezing point up to several hundred degrees above the boiling point are presented. The results show good agreement between the density values obtained from this equation and the experimental and literature data. To show the ability of this EoS in prediction of density of alkali metal alloys, the results have been compared with some other equations. Although there is no corresponding literature data to compare the results obtained for derived thermodynamic properties, the variations of these properties with temperature and composition show proper trends for these alloys.

Volumetric Study of (3-Ethoxypropan-1-amine + Water) Mixtures between (283.15 and 303.15) K

Experimental densities were obtained in the binary mixtures water + 3-ethoxypropan-1-amine, for the whole composition range and at temperatures between (283.15 and 303.15) K. Derived thermodynamic properties such as apparent molar, excess molar, and excess partial molar volumes have been calculated. Limiting partial molar volumes and isobaric expansions were obtained for the two components. Different patterns of molecular aggregation and hydration schemes were detected.

Density and Derived Thermodynamic Properties of 1-Ethyl-3-methylimidazolium Alkyl Sulfate Ionic Liquid Binary Mixtures with Water and with Ethanol from 288 K to 318 K

We present in this paper experimental measurements of density for pure ionic liquids of the 1-ethyl-3-methylimidazolium alkyl sulfate family, with the alkyl group being ethyl ([EMIM][ES]), butyl ([EMIM][BS]), hexyl ([EMIM][HS]), and octyl ([EMIM][OS]), and their binary mixtures with water and with ethanol in the whole composition range, at 288 K, 298 K, 308 K, and 318 K and under atmospheric pressure. The IL family chosen allows us to analyze the influence of the alkyl chain length of the anion. We compare results with those previously published by us and by other research groups, where the influence of the alkyl chain length of the cation in volumetric properties is studied. We observed that the density for both kind of binary mixtures decreases with the increase of the alkyl chain length of the anion and with the decrease of the molar fraction of ionic liquid. From density data we extract molar volumes and excess molar volumes. Molar volumes can be adjusted to a straight line versus the molar fraction, and the excess molar volumes values are very small (less than 0.5 % of the molar volume value) for all of the measured systems. This fact allows us to state that these binary systems are quasi ideal from the molar volume point of view. Finally we study the influence of temperature on this property by means of isobaric expansivity, finding very different results depending on the solvent used.