共查询到20条相似文献,搜索用时 15 毫秒
1.
Xavier Paredes Olivia Fandiño Alfonso S. Pensado María J.P. Comuñas Josefa Fernández 《The Journal of chemical thermodynamics》2012,44(1):38-43
Experimental densities and dynamic viscosities of di(2-ethylhexyl)sebacate (DEHS) are the object of study in this work. DEHS could be a useful industrial reference fluid for moderately high viscosity at high pressures as it is often used as a pressure transmitting fluid. At atmospheric pressure the density and viscosity measurements have been performed in a rotational SVM 3000 Stabinger viscometer from (273.15 to 373.15) K, whereas from (0.1 to 60) MPa and from (298.15 to 398.15) K an automated Anton Paar DMA HPM vibrating-tube densimeter, and a high-pressure rolling-ball viscometer were used. Several Vogel–Fulcher–Tammann type equations were used to fit the experimental values of viscosity to the pressure and temperature. The measured viscosity data have been used together with previous data found in the literature to establish a correlation of the viscosity surface η(T, p) of DEHS, covering a temperature range from (273 to 491) K and pressure up to 1.1 GPa. This correlation could be used in industrial equipment like viscometers and other devices that operate at high pressures. Our viscosity data have also been fitted as a function of temperature and volume to the thermodynamic scaling model of Roland et al. [C.M. Roland, S. Bair, R. Casalini, J. Chem. Phys. 125 (2006) 124508]. 相似文献
2.
José J. Segovia Olivia Fandiño Enriqueta R. López Luis Lugo Ma. Carmen Martín Josefa Fernández 《The Journal of chemical thermodynamics》2009,41(5):632-638
In this work, we present the automatization of a densimetric system for pVT measurements of compressed fluids, operating over the temperature range from 283.15 K to 398.15 K and pressures up to 70 MPa. The heart of the automatic assembly is a commercial Anton Paar DMA HPM vibrating-tube densimeter. The densimeter was calibrated using the method developed by Lagourette et al. and modified recently by Comuñas et al. The fluids used in this calibration were a vacuum, water, and n-decane. Data reliability has been verified by comparing our experimental results for toluene with literature data. The uncertainty of the experimental density was evaluated following the rigorous procedure of the EA-4/02 guide. Moreover, new density measurements of pentaerythritol tetrapentanoate ester are presented. For this fluid with significant viscosity values, a correction factor was applied to take into account the damping effects in the densimeter cell. 相似文献
3.
Density values for dilute aqueous solutions of five cyclic ethers obtained using the Anton Paar DSA 5000 vibrating-tube densimeter and the laboratory-made flow densimeter are presented together with partial molar volumes at infinite dilution (standard partial molar volumes) calculated from the measured results. The cyclic ethers were either five-members cycles with one or two oxygen atoms (oxolane, 1,3-dioxolane) or six-members cycles with one, two, or three oxygen atoms (oxane, 1,4-dioxane, 1,3,5-trioxane). The measurements were performed at temperatures from T = 278 K up to T = 373 K and at either atmospheric pressure or at p = 0.5 MPa. The group contribution method is proposed and values of group contributions are evaluated. Standard partial molar volumes predicted for several other cyclic ethers including large cycles (crown ethers) are compared with available data from the literature. 相似文献
4.
The viscosity of carbon dioxide was measured over the temperature range T = (253.15 to 473.15) K with pressures up to 1.2 MPa utilizing a new rotating-body viscometer. The relative expanded combined uncertainty (k = 2) in viscosity (including uncertainties of temperature and pressure) was (0.20 to 0.41)%. The instrument was specifically designed for measurements at low gas densities and enables measurements of the dynamic viscosity at temperatures between T = 253.15 K and T = 473.15 K with pressures up to 2 MPa. For carbon dioxide, the fluid specific measuring range with regard to pressure was limited to 1.2 MPa due to the formation of disturbing vortices inside the measuring cell at higher pressures. The model function for the viscosity measurement was extended in such a way that the dynamic viscosity was measured relative to helium. Therefore, the influence of the geometry of the concentric cylindrical system inside the measuring cell became almost negligible. Moreover, a systematic offset resulting from a small but inevitable eccentricity of the cylindrical system was compensated for. The residual damping, usually measured in vacuum, was calibrated in the entire temperature range using viscosity values of helium, neon and argon calculated ab initio; at T = 298.15 K recommended reference values were used. A viscosity dependent offset of the measured viscosities, which was observed in previously published data, did not occur when using the calibrated residual damping. The new carbon dioxide results were compared to other experimental literature data and to the correlation, which is currently considered the reference for viscosities of carbon dioxide. 相似文献
5.
《Fluid Phase Equilibria》2006,245(1):32-36
New experimental densities and surface tensions for n-nonane + 1-hexanol at 288.15, 298.15 and 308.15 K are reported. Densities were measured with an Anton Paar DMA 4500 densimeter, and surface tensions using a Lauda TVT2 automated tensiometer, which uses the principle of the pending drop volume. The experimental data of pure liquids and mixtures have been used to calculate excess molar volumes and surface tension deviations of n-nonane + 1-hexanol as a function of mole fractions. A comparative study of these properties together with those available in the literature for the n-alkane + 1-alkanol mixtures has been performed. In addition, the magnitude of these experimental quantities is discussed in terms of the nature and type of intermolecular interactions in binary mixtures. 相似文献
6.
《The Journal of chemical thermodynamics》2003,35(3):383-391
In this work, our objective is to contribute to the knowledge of the mixtures (alcohol + polyalkyl ether glycol) used in absorption refrigeration systems and heat pumps. The determination of different thermophysical properties is essential to understand the interactions among different molecules in liquid mixtures. Therefore, experimental data of speed of sound and density together with calculated values of isentropic compressibility for the refrigerant-absorbent system (methanol + polyethylene glycol dimethyl ether 250) (or Pegdme 250) have been gathered here over the whole range of composition at temperatures from T=293.15 to 333.15 K and atmospheric pressure. The two previous experimental properties were measured with a digital vibrating tube analyser Anton Paar DSA-48. Also, the excess molar volumes and the increments of the speed of sound and the isentropic compressibility have been determined for each composition and they were fitted to a variable-degree polynomial equation. 相似文献
7.
F.A.M.M. Gonçalves A.R. Trindade C.S.M.F. Costa J.C.S. Bernardo I. Johnson I.M.A. Fonseca A.G.M. Ferreira 《The Journal of chemical thermodynamics》2010,42(8):1039-1049
In this work, the results of density, viscosity, and surface tension measurements for ethanol are presented. Ethanol with stated mass fraction purity greater than 0.998 was further purified using molecular sieves. Density was measured within the temperature and pressure ranges, respectively, T = (278.15 to 353.15) K and p = (0.1 to 35) MPa by means of a vibrating tube densimeter, model DMA 512P from Anton Paar with an estimated uncertainty of ±0.5 kg · m?3. The experimental (p, ρ, T) results have been correlated by Tait equation. From this equation the isobaric expansivity, the isothermal compressibility, and the thermal pressure coefficient have been calculated. Viscosity was measured over the range T = (273.15 to 346.15) K using an Ubbelohde viscometer with a Schott–Geräte automatic measuring unit (Model AVS-470) with the associated uncertainty of ±0.001 mPa · s. The measured values were combined with selected values from the literature covering the range T = (223 K to 503) K, and the VTF model has been fitted to all the data. The surface tension of the liquid was measured using a tensiometer KSV Sigma 70 with a Du-Noüy ring for the range of T = (274.77 to 318.99) K with an uncertainty of ±0.01 mN · m?1. Using these data and critically assessed data of other authors compiled from the literature, a form of the IAPWS equation was used to correlate the surface tension within the temperature range 223 K up to the critical temperature. 相似文献
8.
This work reports new experimental density data (954 points) for binary mixtures of 1-heptanol + heptane over the composition range (seven compositions; 0 ⩽ 1-heptanol mole fraction x ⩽ 1), between 298.15 and 393.15 K, and for 23 pressures from 0.1 MPa up to 140 MPa. An Anton Paar vibrating tube densimeter, calibrated with an uncertainty of ±0.7 kg · m−3 was used to perform these measurements. The experimental density data were fitted with a Tait-like equation with low standard deviations. Excess volumes have been calculated from the experimental data. In addition, the isobaric thermal expansivity and the isothermal compressibility have been derived from the Tait-like equation, provided as supplementary material. 相似文献
9.
Fatima E.M. Alaoui Eduardo A. Montero Jean-Patrick Bazile Fernando Aguilar Christian Boned 《The Journal of chemical thermodynamics》2011,43(11):1768-1774
This work reports new experimental density data (445 points) for binary mixtures of (dibutyl ether + 1-butanol) over the composition range (five compositions; 0.15 ? dibutyl ether mole fraction x ? 0.85), from (293.15 to 393.15) K (every 20 K), and for 15 pressures from (0.1 to 140) MPa (every 10 MPa).An Anton Paar vibrating tube densimeter, calibrated with an uncertainty of ±0.5 kg · m?3 was used to perform these measurements. The experimental density data were fitted with a Tait-like equation with low standard deviations. Excess volumes have been calculated from the experimental data and fitted by the Redlich–Kister equation. In addition, the isobaric thermal expansivity and the isothermal compressibility have been derived from the Tait-like equation. 相似文献
10.
F.A.M.M. Gonçalves C.S.M.F. Costa J.C.S. Bernardo I. Johnson I.M.A. Fonseca A.G.M. Ferreira 《The Journal of chemical thermodynamics》2011,43(2):105-116
In spite of the great importance of the PVT data of dichloromethane, only limited information on these data seems to be available in the literature. In this work, we present experimental densities of the liquid dichloromethane over the ranges T = (270 to 330) K and p = (0.1 to 30) MPa using a vibrating tube densimeter, model DMA 512P from Anton Paar with an estimated uncertainty lower than ±0.5 kg · m?3. The high consistency of our data compared with those measured by other authors allows that all the experimental results have been combined and correlated together with the Tait equation in the temperature and pressure ranges T = (244 to 430) K and p = (0.1 to 101) MPa. From the Tait equation, thermomechanical coefficients as the isothermal compressibility, isobaric expansivity, thermal pressure, and internal pressure were calculated. Some of the measurements of density were made at pressures lower than the critical pressure which enabled us to obtain very reliable values for the density of the saturated liquid within the range T = (270.0 to 330.0) K. These data were combined with other values existing in the literature, which made it possible to extend the information on the saturated liquid density to the range T = (208 to 399) K. From these data, a new equation describing the saturated liquid density of dichloromethane was found covering the entire temperature range between the triple and the critical temperatures. A new equation for the vapour pressure was found by using selected values from the literature covering the entire temperature range between the triple and the critical temperatures. 相似文献
11.
A new falling-body viscometer has been implemented to measure viscosity of liquids in a temperature range from (313.15 to 363.15) K at pressures up to 150 MPa. The accuracy of the viscometer was verified after comparing experimental results of squalane with previous literature data finding an average absolute deviation lower than 1.5%. With this device, we have measured viscosity values for three ionic liquids: 1-ethyl-3-methylimidazolium ethylsulfate, 1-butyl-1-methylpyrrolidinium bis(trifluoro-methylsulfonyl)imide and 1-(2-methoxyethyl)-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide within the temperature and pressure ranges noted above. The experimental values were correlated as a function of temperature and pressure with four different equations. In addition, we have analysed the pressure–viscosity derived properties for these fluids and for other five ionic liquids using literature values. 相似文献
12.
《The Journal of chemical thermodynamics》2002,34(5):657-667
Measurements of the ( pρT) properties of three natural gas mixtures were carried out at temperatures from 265 K to 335 K and at pressures up to 15 MPa using a densimeter consisting mainly of a DMA 512P measuring cell and a DMA 60 evaluating unit (Anton Paar, Graz, Austria). Four isotherms {(253.15, 273.15, 293.15 and 323.15) K} and seven pressure levels from 0.1 MPa to 15 MPa were investigated for each natural gas mixture at densities ranging from 6 kg · m − 3to 212 kg · m − 3. The natural gas mixtures were two real gases from transport pipelines systems of natural gas distributors in the Czech Republic. One sample contained natural gas with nitrogen addition. Four equations of state were examined. The relative deviations of calculated density values from the EOS ranged from ( − 5.8 to 1.8) per cent. The best results were obtained from the AGA8-DC92 EOS, with the relative deviations of calculated density value being within the range ( − 0.02 to 0.02) per cent. 相似文献
13.
Isabel M.S. Lampreia Carlos A. Nieto de Castro 《The Journal of chemical thermodynamics》2011,43(4):537-545
A new method for accurately converting vibrating tube periods of oscillation in density values is presented. This method is based on the fundamental requirement of the non-dependence on pressure of the vibration period of the cell under vacuum. An analytical method permits to correctly evaluate the evacuated vibrating tube periods of the Anton Paar cells namely the high pressure cells, 512 and 512P, as a function of temperature. It is further shown that the previously experimental method for the determination of this parameter is not suitable for obtaining reliable density values. A new simple calibration procedure is described and tested over wide ranges of temperature, T = (283.15 to 323.15) K and pressure, P = (0.1 to 60) MPa. New recommended density values for n-alkanes (C6, C7, C8, and C10) and tetrachloromethane, calculated by the proposed method, are given and compared with literature values in terms of mutual uncertainties. 相似文献
14.
This work reports new density data (159 points) of 2-butanol at seven temperatures between (293.15 and 393.27) K and 23 pressures from (0.1 to 140) MPa (every 5 or 10 MPa). An Anton Paar vibrating tube densimeter, calibrated with an uncertainty of ±0.7 · 10−3 g · cm−3, was used to perform these measurements. The experimental density data were fitted with the Tait-like equation with low standard deviations. In addition, the isobaric thermal expansivity and the isothermal compressibility have been derived from the Tait-like equation. 相似文献
15.
《Fluid Phase Equilibria》2006,245(1):6-19
The viscosity of the binary system ethanol + n-heptane has been measured with a falling-body viscometer for seven compositions as well as for the pure compounds in the temperature range 293.15–353.15 K and up to 100 MPa with an experimental uncertainty of ±2%. At 0.1 MPa, the viscosity has been measured with a classical capillary viscometer (Ubbelohde) with an uncertainty of ±1%. A total of 208 experimental data points are reported. The viscosity behavior of this binary system is interpreted as the results of changes in the free volume, and the breaking or weakening of hydrogen bonds. The excess activation energy for viscous flow of the mixtures is negative with a maximum absolute value of 0.3 kJ mol−1, indicating a very weakly interacting system. The data of this binary system as well as those recently measured for ethanol + toluene have been used to study the performance of some viscosity models with a physical and theoretical background. The evaluated models are based on the hard-sphere scheme, the concepts of the free-volume and the friction theory, and a model derived from molecular dynamics. In addition to these models, the simple compositional models by Grunberg–Nissan and Katti–Chaudhri have also been applied. Overall a satisfactory representation of the viscosity of these two binary ethanol + C7 hydrocarbon systems is found for the different models within the considered T, P range taking into account their simplicity. 相似文献
16.
In this work, densities of two binary systems of {alkanol (ethanol and 1-propanol) + boldine} are measured at temperatures from (313 to 363) K and pressures up to 20 MPa using an Anton Paar vibrating tube densimeter. Each (alkanol + boldine) system was prepared at five diluted compositions with respect to the alkaloid. These are (x2 = 0.0012, 0.0074, 0.0136, 0.0196, 0.0267) and (x2 = 0.0018, 0.0046, 0.0077, 0.0112, 0.0142) mixed in ethanol and 1-propanol, respectively. Experimental densities are correlated using an empirical 6-parameter equation with deviations within 0.04%. Extrapolated densities at atmospheric pressure agree with the literature data. Isobaric expansivity, isothermal compressibility, thermal pressure coefficient, and internal pressure have been calculated. 相似文献
17.
《The Journal of chemical thermodynamics》2001,33(9):987-997
Excess molar volumes VmEof (1,2-propanediol + water) and (1,2-butanediol + water) were measured at temperatures of (288.15, 298.15, and 308.15) K and at pressures of (0.1, 20, 40, and 60) MPa with a densimeter, model DMA 512p from Anton Paar. Values of VmEwere negative for all the mixtures studied over the whole concentration range and for all temperatures and pressures. Results were correlated by polynomial equations of Redlich and Kister and of Myers and Scott. 相似文献
18.
Masatoshi Yoshimura Christian Boned Antoine Baylaucq Guillaume Galliéro Hideharu Ushiki 《The Journal of chemical thermodynamics》2009,41(3):291-300
This work reports the dynamic viscosity data (a total of 72 points) of a series of primary amines which exhibit small association consisting of pentylamine, hexylamine and heptylamine at four temperatures between (293.15 and 353.15) K (every 20 K), and pressures up to 100 MPa (every 20 MPa) which allows to study the influence of the chain length. A falling body viscometer with an uncertainty of ±2% was used to perform these measurements.The variations of dynamic viscosity are discussed with respect to their behavior due to chain length. Six different models, most of them with a physical and theoretical background, are studied in order to investigate how they take the chain length influence and effect into account through their required model parameters. The evaluated models are based on the empirical Vogel–Fulcher–Tamman (VFT) representation (combined with Tait-like equation), the rough hard-sphere scheme, the concept of the free-volume, the friction theory and a correlation derived from molecular dynamics. A recent scaling viscosity model has also been considered. These models need some adjustable parameters except the molecular dynamic correlation which is entirely predictive. Overall a satisfactory representation of the viscosity of these amines is found for the different models within the considered T, p range taking into account their simplicity. Moreover it has been verified that the viscosity is a unique function of TVγ where the exponent γ is related to the steepness of the intermolecular repulsive potential (T: temperature, and V: specific volume). 相似文献
19.
F. Peleties J.J. Segovia J.P.M. Trusler D. Vega-Maza 《The Journal of chemical thermodynamics》2010,42(5):631-639
We report measurements of the thermodynamic properties of liquid di-isodecyl phthalate (DIDP) and an equation of state determined therefrom. The speed of sound in DIDP was measured at temperatures between (293.15 and 413.15) K and a pressures between (0.1 and 140) MPa with a relative uncertainty of 0.1%. In addition, the isobaric specific heat capacity was measured at temperatures between (293.15 and 423.15) K at a pressure of 0.1 MPa with a relative uncertainty of 1%, and the density was measured at temperatures between (273.15 and 413.15) K at a pressure of 0.1 MPa with a relative uncertainty of 0.015%. The thermodynamic properties of DIDP were obtained from the measured speeds of sound by thermodynamic integration starting from the initial values of density and isobaric specific heat capacity obtained experimentally. The results have been represented by a new equation of state containing nine parameters with an uncertainty in density not worse than 0.025%. Comparisons with literature data are made. 相似文献
20.
Thermophysical properties, {(p, ρ, T) at T = (283.15 to 393.15) K, pressures up to p = 100 MPa, and viscosity at T = (283.15 to 373.15) K and p = 0.101 MPa}, of 1-butyl-4-methylpyridinium tetrafluoroborate [b4mpy][BF4] are reported. The measurements were carried out with a recently constructed Anton-Paar DMA HPM vibration-tube densimeter and a fully automated SVM 3000 Anton-Paar rotational Stabinger viscometer. The vibration-tube densimeter was calibrated using double-distilled water, methanol, toluene, and aqueous NaCl solutions.An empirical equation of state for fitting of the (p, ρ, T) data of [b4mpy][BF4] has been developed as a function of pressure and temperature to calculate the thermal properties of the ionic liquid (IL), such as isothermal compressibility, isobaric thermal expansibility, differences in isobaric and isochoric heat capacities, thermal pressure coefficient, and internal pressure. Internal pressure and the temperature coefficient of internal pressure data were used to make conclusions on the molecular characteristics of the IL. 相似文献