Saturated Liquid Viscosity Research Articles

The isobaric specific heat capacity and viscosity for 3,3,3-trifluoroprop-1-ene in liquid phase at temperatures from (230 to 293) K and pressures up to 8 MPa

In this paper, the 65 isobaric specific heat capacity (cp) and 9 viscosity (η) data of 3,3,3-trifluoroprop-1-ene (R1243zf) were measured at temperatures from (230 to 293) K and pressure up to 8 MPa using a flow calorimeter and a vibrating-wire viscometer. The uncertainty of temperature, pressure, isobaric specific heat capacity and viscosity were evaluated to be less than 11 mK, 0.02 MPa, 1.0 % and 2.7 %, respectively. Three saturated liquid viscosity (ηs) data were obtained based on the extrapolation of the viscosity data. Empirical correlations were established based on the cp and ηs data, the average absolute relative deviation for cp and ηs are 0.5 % and 1.3 %, respectively.

Surface tension and viscosity of binary ionic liquid mixtures from high vacuum up to pressures of 10 MPa

In the present study, we investigated the surface tension and viscosity of binary ionic liquid (IL) mixtures at or close to saturation conditions from high vacuum conditions up to elevated pressures. We studied four different mixtures of 1,3-bis(2-(2-methoxyethoxy)ethyl)imida-zolium iodide ([(mPEG2)2Im]I) and 1-methyl-3-octylimidazolium hexafluorophosphate ([C8C1Im][PF6]) with [C8C1Im][PF6] mole contents between (4.6 and 49.8) mol%. Argon (Ar) gas of relatively low solubility was used to vary the applied pressure between (0.1 and 10) MPa. For temperatures from (303 to 363) K, the surface tension obtained by the pendant-drop (PD) method was used to determine the saturated liquid viscosity from surface light scattering (SLS). These studies are complemented by additional PD measurements under ultraclean high vacuum (HV) conditions in a second setup. At about 0.1 MPa, the surface tension and viscosity of the IL mixtures show negative deviations from a linear mixing rule based on the molar bulk composition, which is more pronounced at lower temperatures. The surface tension values at 0.1 MPa and under HV agree with each other and lie closer to the values of [C8C1Im][PF6] that has a distinctly lower surface tension than [(mPEG2)2Im]I and is surface-active. For the equimolar IL mixture at 303 K, an increase in the pressure up to 10 MPa has a negligible influence on the viscosity, while it causes a distinct reduction in the surface tension compared to the value at 0.1 MPa. The pressure-dependent relative change for the viscosity of the ternary mixtures of the two ILs and Ar corresponds well to the mean values of the positive and negative relative changes observed for the two binary [(mPEG2)2Im]I-Ar and [C8C1Im][PF6]-Ar subsystems, respectively. For the surface tension, the absolute changes at a given pressure are very similar regardless of the IL bulk composition, suggesting a similar weak Ar enrichment at the gas–liquid interface.

Improved liquid viscosity prediction with the novel TLVMie force field for branched hydrocarbons

The recently developed TLVMie (Transferable Liquid Viscosity Mie) force field for accurate estimation of liquid viscosity and density from standardized molecular simulation is extended to include compounds containing alkyl branching. The prediction capability is evaluated with 49 branched alkanes and 6 branched alkylbenzenes. Performance is compared to: experimental data for compounds outside the training set used to parameterize the model, molecular simulation using the MiPPE and TraPPE force fields, and existing group contribution and corresponding states methods. Experimental saturated liquid densities are predicted to within 0.42% average absolute error and saturated liquid viscosities are reproduced with an average absolute error of 5.7%. Viscosity prediction accuracy is shown to be superior to existing techniques while also being more transferable to compounds or conditions with little experimental data.

Viscosity measurement for trans-1,1,1,4,4,4-hexafluoro-2-butene (R1336mzz(E)) in liquid and vapor phases

As one of hydrofluoroolefins, trans-1,1,1,4,4,4-hexafluoro-2-butene (R1336mzz(E)) is treated as a novel working substance for organic Rankine cycles as well as heat pumps for its low GWP, non-flammability, and lower toxicity. The objectives of this study are the viscosity measurement for R1336mzz(E) in liquid, vapor, and supercritical regions by the method of tandem capillary tubes and the development of correlations for the saturated liquid and vapor viscosities. The viscosity measurements for R1336mzz(E) were conducted over the range of temperature from 314 to 394 K for the liquid, 391 to 453 K for the vapor, and 413 to 453 K for the supercritical region, respectively, at pressures from 1.0 to 4.0 MPa. The expanded uncertainties in the viscosity measurement are calculated as 2.26 % for liquid, 2.30 % for vapor, and 2.32 % for supercritical phase using k=2 and 95 % confidence level. The experimental data are correlated with the ECS model; the AAD is 5.04 % for the liquid, 22.19 % for the vapor, and 11.88 % for the supercritical phase, respectively. The saturated viscosities are also estimated by the extrapolation from the measurements to the liquid-vapor saturation conditions. For industrial design and simulation, simple correlations are developed in terms of the saturation temperature to predict the viscosities of the saturated liquid and vapor phases, respectively.

Development of a rolling ball viscometer for simultaneous measurement of viscosity, density, bubble-point pressure of CO2-expanded liquids

In this work, a rolling ball viscometer was developed that makes it possible to measure viscosity, density, and phase equilibria simultaneously. The cell is mounted inside a high-pressure vessel and can be used at pressures up to 30 MPa and temperatures up to 200 °C. Calibration of the viscometer was carried out by using water at inclined angles from 10° to 30° at temperatures of 40 °C and 80 °C and at pressures up to 20 MPa with toluene viscosity being used for confirmation; viscosity measurements of toluene were found to agree with literature data to within 0.66% in average relative deviation. Viscosity, density, and bubble-point pressure of ethanol + CO2 systems were measured at 40 °C; bubble-point pressures for the ethanol + CO2 system agreed to within 2.2% of the literature. Viscosity of the ethanol + CO2 system were measured at saturated and pressurized liquid states and viscosity values decreased with increasing CO2 composition, and decreased to about half the value of pure ethanol for 0.32 mol fraction of CO2.

Improvements and limitations of Mie λ-6 potential for prediction of saturated and compressed liquid viscosity

Over the past decade, the Mie λ-6 (generalized Lennard-Jones) potential has grown in popularity due to its improved accuracy for predicting vapor-liquid coexistence densities and pressure compared to the traditional Lennard-Jones 12-6 potential. This manuscript explores the hypothesis that greater accuracy in characterizing the coexistence properties may lead to greater accuracy for viscosity predictions. Four united-atom force fields are considered in detail: the Transferable Potentials for Phase Equilibria (TraPPE-UA and the recently developed TraPPE-2) model of Siepmann and coworkers, the Transferable Anisotropic Mie (TAMie) model of Gross and coworkers, the fourth generation anisotropic-united-atom (AUA4) model of Ungerer and coworkers, and the model of Potoff and coworkers.Equilibrium molecular dynamics simulations are analyzed using the Green-Kubo method for viscosity characterization. Simulations are performed for linear alkanes with two to twenty-two carbons and branched alkanes with four to eight carbons. Simulation conditions follow the saturated liquid from reduced temperatures of 0.5–0.85 and along the 293 K isotherm in the dense liquid region.In general, the more accurate force fields for coexistence properties do indeed predict viscosity more accurately. For saturated liquids, both Mie-based potential models (Potoff and TAMie) provide roughly 10% accuracy for linear alkanes, while deviations are between 20 and 50% for TraPPE-UA. For branched alkanes, the performance is slightly diminished, but Potoff still provides roughly 15–20% accuracy, while the TAMie force field results in deviations of 20–40%, and TraPPE-UA has deviations of approximately 25–60%. The AUA4 deviations are 10–20% for ethane and 30–60% for 2,2-dimethylpropane, the only compounds tested with the AUA4 force field. The TraPPE-2 deviations for ethane are similar to those using the original TraPPE force field, namely, between 10 and 20%. The percent deviations for each compound and force field tend to increase with decreasing temperature, with the exception of the Potoff deviations for propane, which are nearly constant to the triple point temperature.For compressed liquids, the Mie-based potential models perform better once again than the Lennard-Jones-based force fields, but tend to over estimate the viscosity at very high densities. As the Potoff and TAMie models also tend to over estimate the pressure at high densities, a fortuitous cancellation of errors leads to predictions of viscosity with respect to pressure that are accurate to within about 10%. The comparison with experimental viscosity data is limited to pressures below 200 MPa for most normal and branched alkanes. However, accurate predictions are obtained for propane near 1000 MPa with the Potoff force field.

Esmaeilzadeh–Roshanfekr equation of state coupled with CPA model: Application in viscosity modeling

AbstractThe present study aims to evaluate the performance of the cubic plus association model for the estimation of physical properties of associating fluids. In this regard, this model with different physical terms was evaluated. Soave–Redlich–Kwong, Peng–Robinson, Patel–Teja, and Esmaeilzadeh–Roshanfekr cubic equations were utilized as the physical contribution in the model. This was the first study to evaluate 3‐parameter equations such as Patel–Teja and Esmaeilzadeh–Roshanfekr. Experimental vapor pressure and saturated liquid molar densities were employed to obtain the parameters of pure components. All the models were capable of representing the data. However, new cubic plus association equations of states showed better performance due to the presence of an additional fitting parameter. These parameters were then used to calculate liquid viscosity data of associating fluids in a broad range of temperature and pressure. Free volume and friction theories were applied for this purpose. All the models were successful in estimation of viscosity data. However, friction models managed to obtain less error. Maximum observed error, which was less than 5%, was obtained in estimation of ethylene glycol viscosity by the free volume theory. Consequently, cubic plus association models with different physical terms can precisely estimate physical properties of highly associating fluids. Besides, the application of 3‐parameter equations for the physical contribution leads to better estimations in both saturated liquid densities and liquid viscosities.

Solubility of n-Butane in Athabasca Bitumen and Saturated Densities and Viscosities at Temperatures Up to 200°C

Summary The steam- and/or solvent-based recovery processes are efficient methods for recovery of heavy and extraheavy oils. The performance of these techniques depends on the amount of solvent dissolved in the oil and the variation of oil viscosity with temperature. Thus, full understanding of the quantitative effects of the solvent on heavy-oil viscosity and phase behavior is crucial for feasibility studies, design, and prediction of field-scale processes. Phase-behavior study of bitumen diluted with heavy hydrocarbon solvents, such as butane and pentane, has gained less attention in recent years. These solvents, as good candidates for recently developed recovery methods such as expanding solvent steam-assisted gravity drainage (ES-SAGD), could provide promising oil-production rates. Thus, the aim of this research is the development of an understanding of the phase behavior of n-butane/Athabasca-bitumen mixtures. It includes both experimental and modeling studies of solubilities and saturated liquid densities and viscosities over wide ranges of temperatures (up to 200 °C) and pressures (up to 8 MPa). Experimental results indicate that the dissolved n-butane in bitumen leads to a significant oil-viscosity reduction, and the effect is more pronounced at lower temperatures and/or higher pressures. The modeling results show that the measured solubilities are adequately represented by the Peng-Robinson equation of state (EOS) with an average absolute relative deviation (AARD) of 9.7%. The saturated liquid densities are also correlated with both the EOS and the effective liquid-density approach with 0.86 and 0.55% AARDs, respectively. The viscosity data are reasonably matched with Pedersen corresponding state.

Solubility of carbon dioxide, methane, and ethane in 1-butanol and saturated liquid densities and viscosities

A designed pressure–volume–temperature (PVT) apparatus has been used to measure the (vapor+liquid) equilibrium properties of three binary mixtures (methane +, ethane +, and carbon dioxide + 1-butanol) at two temperatures (303 and 323)K and at the pressures up to 6MPa. The solubility of the compressed gases in 1-butanol and the saturated liquid densities and viscosities were measured. In addition, the density and viscosity of pure 1-butanol were measured at two temperatures (303 and 323)K and at the pressures up to 10MPa. The experimental results show that the solubility of the gases in 1-butanol increases with pressure and decreases with temperature. The dissolution of gases in 1-butanol causes a decline in the viscosity of liquid phase. The saturated liquid density follows a decreasing trend with the solubility of methane and ethane. However, the dissolution of carbon dioxide in 1-butanol leads to an increase in the density of liquid phase. The experimental data are well correlated with Soave–Redlich–Kwong (SRK) and Peng–Robinson (PR) equations of state (EOSs). SRK EOS was slightly superior for correlating the saturated liquid densities.

Experimental and modeling investigations of solubility and saturated liquid densities and viscosities for binary systems (methane +, ethane +, and carbon dioxide + 2-propanol)

Solubilities of methane, ethane, and carbon dioxide in 2-propanol have been measured at the temperatures (303 and 323)K and at the pressures up to 6MPa using an in-house designed PVT apparatus. The saturated liquid properties, density and viscosity, were also measured in each experiment. Prior to the phase equilibrium measurements, the density and viscosity of pure 2-propanol were measured at the temperatures (303 and 323)K over the pressure range (0.1 to 10)MPa. The dissolution of carbon dioxide in 2-propanol caused a decline in the viscosity of saturated liquid phase while an increase in the density of gas-expanded liquid was observed. The viscosity-pressure trends for methane- and ethane-saturated liquid viscosities were similar to carbon dioxide, but the saturated liquid densities decreased with the dissolution of methane and ethane in 2-propanol. Solubility increased with pressure and decreased with temperature for all compressed gases (methane, ethane and carbon dioxide). The experimental data were well correlated using Soave–Redlich–Kwong and Peng–Robinson equations of state. The solubilities and saturated liquid densities were well represented with both equations of state, and there is no superior equation of state for the modeling of the phase compositions and saturated liquid densities.

Predictive Corresponding-States Viscosity Model for the Entire Fluid Region: n-Alkanes

Previous work by the author demonstrated a novel approach for correlating the scaled self-diffusion coefficient, viscosity, and thermal conductivity with the residual entropy over the entire fluid region. It is shown here that a new entity-based scaled viscosity model correlates pure n-alkane components to a single semilogarithmic line with the entity residual entropy. With five fitting parameters, a 5.2% group average of the absolute relative deviations (AADs) is obtained over the entire fluid region for a group of 17 n-alkanes, ranging from methane to linear polyethylene with a molecular weight of 1280 g/mol. It was also found that these same five fitting parameters predict the fluid viscosity of some other alkanes, ethers, and olefins. Thus, the entity-based scaling approach introduced here provides a predictive corresponding-states model for fluid viscosity of nonassociating molecules and is a practical approach to determining viscosity in process engineering, product engineering, oil and gas reservoir engineering, pipelines, and fracking applications. This entity-based scaled viscosity-entity residual entropy model is particularly useful in the critical region and at high pressures because the traditional saturated liquid and saturated vapor viscosity component correlations are not applicable.

Saturated Liquid Viscosity of Ethyl Fluoride (HFC161) from 233 K to 373 K

The liquid viscosity of ethyl fluoride (HFC161) was measured over the temperature range from (233 to 373) K along the saturation line with a calibrated capillary viscometer. The estimated uncertainty of the measurement was less than 3 % for the viscosity. The saturated liquid viscosity of isobutane (HC600a) was measured for verifying the reliability and proper operation of the apparatus. The liquid-viscosity data of HFC161 were correlated as a function of temperature. The average absolute deviation and the maximum deviation of the experimental results from the correlation function are 0.66 % and 2.13 %, respectively.

Experimental measurements and predictions of density, viscosity, and carbon dioxide solubility in methanol, ethanol, and 1-propanol

The solubilities of carbon dioxide in different alcohols, methanol, ethanol, and 1-propanol, were measured at two different temperatures (303.2 and 323.2)K and pressures up to 6MPa. The experimental data of saturated alcohol density and viscosity were also reported at each temperature and pressure. The solubility data shows that the solubility of carbon dioxide in alcohol increases with pressure and decreases with temperatures in the studied pressure and temperature ranges. The higher dissolution of carbon dioxide in alcohols resulted in increase in the saturated liquid densities and decrease in saturated liquid viscosities. The experimental solubility as well as saturated liquid density data were predicted with two cubic equations of state (EOS), Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK). The modeling results demonstrated that both equations of state correlated the solubility data well over the studied pressure and temperature ranges. However, the saturated liquid densities calculated with the SRK EOS were much better than those of PR EOS.

Solubility Measurements and Saturated Liquid Properties of Ternary Systems (Methane + Decane + Octadecane) at 295 K

Experimental vapor–liquid equilibrium (VLE) data have been measured for the ternary system (methane + decane + octadecane) at 295 K over the pressure range (1 to 8) MPa using a PVT apparatus that was designed in-house. Three different (decane + octadecane) binary mixtures were prepared, and the solubility and phase equilibria of these prepared mixtures with methane were studied. The experimental information of saturated liquid phase composition, density, and viscosity was reported at each pressure. The VLE data were correlated with the Soave–Redlich–Kwong (SRK) and Peng–Robinson (PR) equations of state (EOS's). The adjustment of binary interaction parameters and the volume translation technique has been employed to correlate the experimental compositions and densities. The adjusted binary parameters from the VLE data of binary pairs (methane + decane) and (methane + octadecane) were used to correlate the generated ternary VLE data. The calculated ternary VLE compositions were found to be in good agreement with the experimental data using the binary parameters from the VLE data of binary pairs for both EOS's. According to the results for the saturated liquid densities, more accurate predictions of the experimental data were obtained using the PR EOS than the SRK EOS.

Vapor–Liquid Phase Equilibria and Physical Properties Measurements for Ternary Systems (Methane + Decane + Hexadecane)

The vapor–liquid equilibrium (VLE) data for ternary systems (methane + decane + hexadecane) have been determined using a designed pressure–volume–temperature (PVT) apparatus. Three different (decane + hexadecane) binary mixtures were prepared, and the solubility and phase equilibria of three prepared mixtures with methane at ambient temperature and different pressures from (1 to 8) MPa were studied. The phase composition and saturated liquid density and viscosity were reported for each pressure. The VLE data of the ternary mixtures were correlated using Soave–Redlich–Kwong and Peng–Robinson equations of state. The equations of state models with their best-fitted parameters of the binary systems, (methane + decane and methane + hexadecane), were used to predict the VLE data of ternary systems. Both equations of state were found to be capable of describing the phase equilibria of binary pairs and ternary systems over the range of studied conditions. The Peng–Robinson equation of state gave better prediction...

Experimental and thermodynamic modeling study on (vapor + liquid) equilibria and physical properties of ternary systems (methane + n-decane + n-tetradecane)

The vapor–liquid equilibrium (VLE) data of ternary systems (methane+n-decane+n-tetradecane) at ambient temperature and various pressures, 1–8MPa, have been measured using a designed pressure–volume–temperature (PVT) apparatus. The phase compositions and saturated liquid phase properties, density and viscosity, have been measured for each pressure. The densities of three different (n-decane+n-tetradecane) binary mixtures have also been measured at ambient temperature over a wide range of pressures (1–10MPa). The generated experimental data have been correlated with two cubic equations of state (EoS), Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK). The binary interaction parameters and the volume shift values from the experimental information on the binary pairs, (methane+n-decane) and (methane+n-tetradecane), have been used to predict the VLE data of ternary system (methane+n-decane+n-tetradecane). Both equations of state have been found to be capable of describing the phase equilibria of binary pairs as well as ternary systems over the range of studied conditions.

Estimation of pure component properties. Part 4: Estimation of the saturated liquid viscosity of non-electrolyte organic compounds via group contributions and group interactions

A new group contribution method for the prediction of pure component saturated liquid viscosity has been developed. The method is an extension of the pure component property estimation techniques that we have developed for normal boiling points, critical property data, and vapour pressures. Predictions can be made from simply having knowledge of the molecular structure of the compound. In addition, the structural group definitions for the method are identical to those proposed for estimation of saturated vapour pressures. Structural groups were defined in a standardized form and fragmentation of the molecular structures was performed by an automatic procedure to eliminate any arbitrary assumptions. The new method is based on liquid viscosity data for more than 1600 components. Results of the new method are compared to several other estimation methods published in literature and are found to be significantly better. A relative mean deviation in viscosity of 15.3% was observed for 813 components (12,139 data points). By comparison, the Van Velzen method, the best literature method in our benchmarking exercise produced a relative mean deviation of 92.8% for 670 components (11,115 data points). Estimation results at the normal boiling temperature were also tested against an empirical rule for more than 4000 components. The range of the method is usually from the triple or melting point to a reduced temperature of 0.75–0.8. Larger than average deviations were observed in the case of molecules with higher rotational symmetry, but no specific correction of this effect was included in this method.

A viscosity model based on Peng–Robinson equation of state for light hydrocarbon liquids and gases

A viscosity model based on the similarity between P v T and Tμ(viscosity) P relationships for a better description of viscosity has been developed based on Peng–Robinson (PR) cubic equation of state (EOS). The model is able to calculate viscosities of pure or mixed light hydrocarbons with better accuracy. At a saturated state, when the temperature is specified, the PR EOS with Twu's α-function is applied to predict the saturated vapor pressure. Then the saturated liquid and vapor viscosities of pure hydrocarbons can be calculated based on the new viscosity model with the specified temperature and pressure. The new viscosity model is applicable to describe viscosity of hydrocarbons in the near-critical region with a smooth transition like PR EOS for density.

Simultaneous Correlation of Saturated Viscosities of Pure Gases and Liquids Using the Significant Structure Theory

The significant structure theory (SST) for liquid viscosities, originally proposed by Eyring, coupled with a cubic equation of state was used for the simultaneous correlation of gas and liquid viscosities of pure fluids (polar and nonpolar) at saturated conditions. The SST visualizes a liquid as having both solidlike and gaslike degrees of freedom with fluidized vacancies of molecular size randomly distributed throughout a quasi-lattice structure. In this context, the viscosity of a liquid is calculated from two main components: a gaslike η g and a solidlike η s contribution. The first viscosity contribution η g represents the viscosity of a pure fluid at dilute gas conditions (low-pressure viscosity). The method of Chung et al. based on the Chapman-Enskog kinetic theory of gases was used to calculate η g . The second contribution η s captures the solidlike effects on viscosity. This quantity was calculated by means of Eyring's absolute rate theory. All the thermodynamic properties required in the viscosity model were computed via the use of a well-known cubic equation of state (Soave-Redlich-Kwong or Peng-Robinson) thus allowing the simultaneous correlation of gas-liquid viscosities along their coexistence curve. The resulting model was satisfactorily validated in the representation of experimental saturated gas and liquid viscosities of a highly polar compound (water) and a nonpolar fluid (propane) over a wide range of temperatures (from near the triple point up to the critical region of the fluid of interest).

Saturated Liquid Viscosity of Cyclopentane and Isopentane

In this paper, the saturated liquid viscosity of cyclopentane and isopentane was measured through the capillary flow method, over the temperature range from 253.15 K to 353.15 K. The results were correlated as a function of temperature. The viscometer was calibrated using water, ethanol, acetone, and ethyl acetate.