A free-volume and friction viscosity model is presented versus pressure and temperature, valid for both gaseous and dense fluids. This model involves only three adjustable parameters for each pure compound. It is able to represent the gas-liquid transition and the behavior in the supercritical conditions. The model has been successfully applied to methane (885 data points for 0.01< or =P< or =200 MPa and 90.7< or =T< or =600 K) and to propane (1085 data points for 0.01< or =P< or =200 MPa and 90< or =T< or =600 K) in the gaseous and dense states (average absolute deviation is 2.59% for methane and 2.50% for propane, with maximum deviation of 14.8% for methane and 9.19% for propane). It has also been applied to hexane, octane, dodecane, benzene, trans-decaline, and 2,2-dimethylpropane (903 data points) in a large pressure range (up to 505.5 MPa). Considering these compounds the maximum deviation is 19.5% (for octane) and the average deviation is 3.51% in the worst case (dodecane, which has data points up to 501.6 MPa).

New density data for diethyl adipate (DEA) over 12 isotherms [(293.15 e T e 403.15) K] and 15 isobars [(0.1 e p e 140) MPa] are reported. This paper presents also the calibration procedure we propose for a new experimental equipment. Data reliability has been verified over the pressure and temperature experimental intervals by comparing our experimental results for toluene and 1-butanol with previous literature data. A total of 732 experimental data points have been measured in the framework of this work. The experimental uncertainty is estimated to be ( 0.5 kg • m -3 (around 0.05 %). The pressure and temperature dependencies of diethyl adipate densities were accurately represented by the Tammann-Tait equation with standard deviations of 0.3 kg • m -3 . These data were used to analyze the isothermal compressibility and the isobaric thermal expansivity for this fluid.

A predictive scheme of viscosity for pure fluids and mixtures of simple molecules is presented. First, using molecular dynamics data from the literature and also from our own study, a representative correlation of the viscosity of a Lennard-Jones fluid is developed for a wide range of thermodynamic states. Second, a corresponding states scheme is proposed which allows the transposition of the previous results to real fluids. For some simple molecules, this scheme induces deviations lower than 5% in conditions covering gas, liquid, and supercritical states. For larger molecules, the results are poorer but can be strongly improved by fitting the atomic diameter. Then, it is shown for simple binary and multicomponent mixtures that, by using merely a van der Waals one-fluid approximation and the Lorentz-Berthelot rules, results are as good as for pure fluids. Finally, the limitations of such a scheme are shown when applied on the methane + toluene asymmetric mixture.

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Viscosity and density are key properties for the evaluation, simulation, and development of petroleum reservoirs. In previous work, the friction theory (f -theory) models have already been shown capable of providing simple but accurate viscosity modeling results of petroleum reservoir fluids with molar masses up to around 200 g · mol −1 . As a base, the f -theory approach requires a compositional characterization procedure to be used in conjunction with a van der Waals type of equation of state (EOS). This is achieved using simple cubic EOS, which are widely used within the oil industry. In this work, the f -theory approach is further extended to the viscosity modeling of heavy reservoir fluids with viscosities up to thousands of mPa · s. Essential to the extended approach presented here is the achievement of accurate pvT results for the EOS characterized fluid. In particular, it has been found that for accurate viscosity modeling of heavy oils, a compressibility correction in the way the EOS is coupled to the viscosity model is required. With the approach presented in this work, the potential of the f -theory for viscosity modeling of reservoir fluids is extended to practically all kind of reservoir fluids, from light ones to heavy ones. Additionally, the approach has been completed with an accurate density modeling scheme.

The viscosity of the ethanol + toluene binary system has been measured with a falling-body viscometer for seven compositions as well as for the pure ethanol in the temperature range from 293.15 to 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 209 experimental measurements have been obtained for this binary system, which reveals a non-monotonic behavior of the viscosity as a function of the composition, with a minimum. The viscosity behavior of this binary system is interpreted as the result 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 335 J · mol −1 , indicating that this binary system is a very weakly interacting system showing a negative deviation from ideality. The viscosity of this binary system is represented by the Grunberg-Nissan and the Katti-Chaudhri mixing laws with an overall uncertainty of 12% and 8%, respectively. The viscosity of methanol (23 point) has also been measured in order to verify the calibration of the falling-body viscometer within the considered T, P range.

The density of the asymmetrical binary system composed of ethanol and heptane has been measured (630 points) for nine different compositions including the pure compounds at five temperatures in the range (293.15 to 333.15) K and 14 isobars up to 65 MPa with a vibrating-tube densimeter, The experimental uncertainty is estimated to be 0.5 kg‚m -3 . The isothermal compressibility, the isobaric thermal expansion, and the excess molar volume have been derived from the experimental density data, revealing that a volume expansion occurs for this binary system. The results have been interpreted as due to changes in the molecular free-volume, disruption of the order molecular structure, and the breaking of hydrogen bonds within the self-associating alcohol.