High-pressure Viscosity Research Articles

Viscosity measurements for squalane at high pressures to 350 MPa from T = (293.15 to 363.15) K

Squalane is being recommended as a secondary reference material for viscometry at moderate to high pressure and at moderate viscosity. As part of this work, a correlation has been developed for atmospheric pressure (Comuñas et al., 2013) [12]. Here we report new experimental high pressure viscosities for squalane (176 data points obtained for temperatures (293.15 to 363.15)K, at pressures up to 350MPa with a maximum viscosity of 745mPa·s). These have been determined with four different falling-body viscometers as well as a quartz crystal resonator viscometer. A preliminary high pressure viscosity correlation for squalane is proposed, based on our new data. At pressures up to 350MPa, this correlation provides an absolute average deviation of 1.5% with a maximum absolute deviation of 8.9%. Comparison is made between the different instruments. In addition, we have also considered the validity of a thermodynamic scaling model.

Exploratory Characterization of a Perfluoropolyether Oil as a Possible Viscosity Standard at Deepwater Production Conditions of 533 K and 241 MPa

DuPont’s perfluoropolyether oil Krytox\(^{\textregistered }\) GPL 102 is a promising candidate for the high-temperature, high-pressure Deepwater viscosity standard (DVS). The preferred DVS is a thermally stable liquid that exhibits a viscosity of roughly 20 \(\hbox {mPa} \cdot \hbox {s}\) at 533 K and 241 MPa; a viscosity value representative of light oils found in ultra-deep formations beneath the deep waters of the Gulf of Mexico. A windowed rolling-ball viscometer designed by our team is used to determine the Krytox\(^{\textregistered }\) GPL 102 viscosity at pressures to 245 MPa and temperatures of 311 K, 372 K, and 533 K. At 533 K and 243 MPa, the Krytox\(^{\textregistered }\) GPL 102 viscosity is \((27.2 \pm 1.3)\,\hbox {mPa} \cdot \hbox {s}\). The rolling-ball viscometer viscosity results for Krytox\(^{\textregistered }\) GPL 102 are correlated with an empirical 10-parameter surface fitting function that yields an MAPD of 3.9 %. A Couette rheometer is also used to measure the Krytox\(^{\textregistered }\) GPL 102 viscosity, yielding a value of \((26.2 \pm 1)\,\hbox {mPa} \cdot \hbox {s}\) at 533 K and 241 MPa. The results of this exploratory study suggest that Krytox\(^{\textregistered }\, \hbox {GPL}\) 102 is a promising candidate for the DVS, primarily because this fluoroether oil is thermally stable and exhibits a viscosity closer to the targeted value of 20 mPa \(\cdot \) s at 533 K and 241 MPa than any other fluid reported to date. Nonetheless, further studies must be conducted by other researcher groups using various types of viscometers and rheometers on samples of Krytox GPL\(^{\textregistered }\) 102 from the same lot to further establish the properties of Krytox GPL\(^{\textregistered }\) 102.

Evaluation of ionic fluids as lubricants in manufacturing

Ionic fluids are liquid salts that have been investigated for a number of applications, including catalysis, their use as solvents and electrically conducting fluids. Chemically, they consist of ionically bonded species, and depending on the cation and anion, can be extremely valuable in the chemical processing industry. Another characteristic that makes them useful is a high viscosity and good lubrication properties. This paper examines a number of ionic fluids, and determines their suitability as lubricants. This involves determining rheological properties, including viscosity and high-pressure viscosity, generally using a Barus law. In addition, their traction behavior is measured to evaluate their lubricating properties. Since metalworking fluids (and lubricants in general) are used in non-isothermal situations, the thermal conductivity of these fluids have also been measured.

Density and Viscosity Measurement of Diesel Fuels at Combined High Pressure and Elevated Temperature

We report the measurement of the viscosity and density of various diesel fuels, obtained from British refineries, at elevated pressures up to 500 MPa and temperatures in the range 298 K to 373 K. The measurement and prediction procedures of fluid properties under high pressure conditions is of increasing interest in many processes and systems including enhanced oil recovery, automotive engine fuel injection, braking, and hydraulic systems. Accurate data and understanding of the fluid characteristic in terms of pressure, volume and temperature is required particularly where the fluid is composed of a complex mixture or blend of aliphatic or aromatic hydrocarbons. In this study, high pressure viscosity data was obtained using a thermostatically-controlled falling sinker-type high pressure viscometer to provide reproducible and reliable viscosity data based on terminal velocity sinker fall times. This was supported with density measurements using a micro-pVT device. Both high-pressure devices were additionally capable of illustrating the freezing points of the hydrocarbon mixtures. This work has, thus, provided data that can extend the application of mixtures of commercially available fuels and to test the validity of available predictive density and viscosity models. This included a Tait-style equation for fluid compressibility prediction. For complex diesel fuel compositions, which have many unidentified components, the approach illustrates the need to apply appropriate correlations, which require accurate knowledge or prediction of thermodynamic properties.

Effect of Compression on the Relationship between Viscosity and Dielectric Relaxation Time in Hydrogen-Bonded Primary Alcohols

High pressure viscosity and dielectric measurements were carried out on two monohydroxy alcohols, 2-ethyl-1-hexanol and 5-methyl-2-hexanol, at room temperature. Analysis of the dielectric relaxation times versus viscosity revealed the breakdown of the Einstein-Debye relation above some characteristic pressure. The failure of the Einstein-Debye relation is a manifestation of pressure induced changes of supramolecular hydrogen bonded structures which occur in these liquids.

Prediction of High Pressure Viscosity of Various Lubricating Oils with Differences in Molecular Structures

Prediction of High Pressure Viscosity of Various Lubricating Oils with Differences in Molecular Structures

Errata:Prediction of High Pressure Viscosity of Various Lubricating Oils with Differences in Molecular Structures [tribologist Vol.58 No.10 701-706

Errata:Prediction of High Pressure Viscosity of Various Lubricating Oils with Differences in Molecular Structures [tribologist Vol.58 No.10 701-706

The Method of the Prediction of the High-Pressure Viscosity for Binary System Mixtures

The Method of the Prediction of the High-Pressure Viscosity for Binary System Mixtures

Dielectric Spectroscopy of Polar Lubricating Oils and Its Application to High-Pressure Viscosity Estimation

Dielectric Spectroscopy of Polar Lubricating Oils and Its Application to High-Pressure Viscosity Estimation

High-Pressure Viscosity of Soybean-Oil-Based Biodiesel Blends with Ultra-Low-Sulfur Diesel Fuel

Current and future injector designs for diesel engines approach pressures of greater than 100 MPa. However, the high-pressure physical properties, such as viscosity, of biodiesel blends with diesel...

Analysis of Straight Vegetable Oil (SVO) Spray Characteristics at End of Injection (EOI)

The depletion source and the increasing demand of fossil fuel have prompted scientists and researchers to search new alternative fuels for diesel engine. Biodiesel is seen a promising alternative fuel to reduce dependent on conventional diesel fuel. Advantages of biodiesel compared to petroleum-based diesel include high biodegradability, excellent lubricity, higher flash point, no sulfur content and produces less air pollutants. Although biodiesel has many advantages on the fuel properties, the fuel consumption rate or lower horsepower output are still need to be improved. This is due to the differences in fuel properties especially the kinematic viscosity between diesel fuel (GO), biodiesel fuel (BDF) and straight vegetable oil (SVO). In this study, the effect of kinematic viscosity of SVO on the spray behavior at End of Injection (EOI) were investigated. High kinematic viscosity of fuel highly affects the spray characteristics at EOI. In additional, high injection pressure and high kinematic viscosity of SVO apply resistance at nozzle inner hole caused needle lift cannot completely close the nozzle at EOI signal. At the EOI in which the combustion temperature inside chamber reduces promptly, many fuel droplets could not undergo a complete atomization process especially for large size of diameter fuel droplets. This phenomenon result the development of carbon deposition around the nozzle tip area and it will cover the nozzle hole. The development of carbon deposition will affect the fuel flow from nozzle. This study indicates that fuel injection pressure show no effect on SVO spray characteristics at the end of injection. Furthermore, high ambient temperature spray will reduce the kinematic viscosity value of SVO and could improve SVO spray atomization at end of injection.

High-Pressure Viscosity of Biodiesel from Soybean, Canola, and Coconut Oils

Current and future injector designs for diesel engines approach pressures of greater than 100 MPa. However, the high-pressure physical properties, such as viscosity, of biologically derived diesel fuel (biodiesel) are nearly absent in the literature. This study focuses on the viscosity of biodiesel samples, fatty acid methyl esters (FAMEs), derived from soybean oil, soybean oil from Vistive soybeans, canola oil, recycled canola oil that has been used in cooking and frying, and coconut oil from 283.15 to 373.15 K and pressures up to 131 MPa. Petroleum-derived diesel (ultra-low sulfur, number 2 diesel) has also been investigated to compare to the biodiesel samples. The viscosity of the samples increases linearly with pressure until approximately 35 MPa, followed by a higher order response to pressure. Except for coconut-oil-derived biodiesel, the biodiesel samples have viscosities that are greater than petroleum-derived diesel at both ambient and elevated pressures. However, at lower temperatures and high pressures, the diesel and biodiesel samples become more similar. The viscosity of the biodiesel samples with pressure can increase nearly 300% over the pressure range investigated over their respective ambient-pressure viscosity; number 2 diesel increases up to ∼400% over similar pressures. The biodiesel samples at 283.15 K were found to experience pressure-induced cloud points (solid−liquid equilibrium) from 70 to 100 MPa, which significantly increases their viscosity. The Tait−Litovitz equation was found to correlate the data very well over the large range of both temperature and pressure.

Asymptotic analysis, regularisation and stable numerical solutions for heavily loaded line EHL contacts

A stable numerical approach is developed for solution of problems for heavily loaded line EHL problems and the asymptotic equations of the problem in the inlet and exit contact zones. The numerical approach is based on two ideas: (i) It uses the form of the original and asymptotic EHL equations resolved for pressure involved in the equations for the gap between the lubricated solids; and (ii) It uses regularisation based on an asymptotic solution of the non-isothermal EHL problem. That allows for a stable solution of the EHL problem even for extremely high dimensionless pressure viscosity coefficients ranging from 0 to 40. Therefore, the paper consists of three parts: (i) Part 1 is devoted to development of an asymptotic approach to solution of heavily loaded EHL contacts and to numerical solution of these equations. This part is very essential as it paves the way to the asymptotic analysis of non-isothermal EHL problem and, consequently, to construction of a stable regularised numerical algorithm; (ii) Part 2 is devoted to asymptotic and numerical analysis of non-isothermal EHL problem for heavily loaded contacts; and (iii) Part 3 is devoted to development of regularised stable numerical solutions of the asymptotic and original equations for heavily loaded EHL contacts. Copyright © 2010 John Wiley & Sons, Ltd.

High-pressure behavior and tribological properties of wind turbine gear oil

Different types of synthetic polyalphaolefin (PAO) oils and a mineral oil are considered in this study. High-pressure viscosity test was done and pressure-viscosity coefficient was measured for all sample oils. Results showed the better performance of PAO oils than the mineral oil. Authors also tested some other tribological properties such as low-temperature behavior, bulk property, frictional coefficient, and wear behavior, which are important for wind turbine gear oil. Low-temperature behavior and frictional property of PAO oils exhibited the better results. Study also showed that the prediction of low-temperature fluidity is possible using the sound velocity in the oil. Finally, the presence of polymethakrylate (PMA) absorbent in PAO oil exposed comparatively better results among all PAO oils.

Combined High Pressure and Low Temperature Viscosity Measurement of Biodiesel

In this work, we report the measurement of the viscosity of biodiesel derived from sunflower oil and biodiesel blend with mineral diesel under combined conditions of high pressure and subambient temperature. Using a thermostatically controlled falling sinker-type viscometer, dynamic viscosity measurements were made at pressures up to 153 MPa, which are typical of those found in common-rail automotive diesel engines, and temperatures down to 0 °C. Reproducible and reliable viscosity data was obtained from sinker fall times. Calibration of the viscometer was based on n-dodecane. Biodiesel viscosities were found to increase exponentially with both rising pressure and reducing temperature. When combined with mineral diesel as a B20 blend, the viscosity was found to be less than for B100 for all temperatures considered. Both pressure and thermal freezing were found to also occur with increasing pressure and lowering temperature.

A study on stability and thermophysical properties (density and viscosity) of Al2O3 in water nanofluid

The dispersion and stability of nanofluids obtained by dispersing Al2O3 nanoparticles (obtained from different sources) in water have been analyzed. The differences arising from different dispersion techniques, the resulting particle size distribution, and time stability among the different samples are evaluated. Then the volumetric behavior up to high pressures (25 MPa) and atmospheric pressure viscosity were experimentally determined. It has been found that the influence of particle size in density is subtle but not negligible, but the differences in viscosity are very large and must be taken into account for any practical application. These viscosity differences can be rationalized by considering a theory describing the aggregation state of the nanofluid.

Viscosity of n-alkyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)amide ionic liquids saturated with compressed CO 2

The viscosity of imidazolium-based ionic liquids (ILs) saturated with gaseous, liquid and supercritical carbon dioxide (CO 2) was measured by a high-pressure viscometer at three different temperatures (25, 50, and 70 °C). The high-pressure viscosity of 1-ethyl-3-methylimidazolium ([EMIm]), 1- n-hexyl-3-methylimidazolium ([HMIm]), and 1- n-decyl-3-methylimidazolium ([DMIm]) cations with a common anion, bis(trifluoromethylsulfonyl)amide ([Tf 2N]), saturated with CO 2 was measured up to a maximum of 287 bar. As CO 2 pressure is increased the viscosity of the IL mixture dramatically decreases. While, the ambient pressure viscosity of 1-alkyl-3-methyl-imidazolium [Tf 2N] ILs increases significantly with increasing chain length, the viscosity of all the CO 2-saturated ILs becomes very similar at high CO 2 pressures. From previous vapor–liquid equilibrium data, the viscosity with concentration was determined and found to be the primary factor to describe the fractional viscosity reduction. Several predictive and correlative methods were investigated for the mixture viscosity given pure component properties and include arithmetic mixing rules, the Irving (Predictive Arrhenius) model, Grunberg equation, etc. The modified Grunberg model with one adjustable parameter provided an adequate fit to the data.

Shear Viscosity of CO2-Plasticized Polystyrene Under High Static Pressures

High-pressure shear viscosity measurements of polymer/supercritical fluid systems are numerous, but most involve pressure-gradient equipment such as a capillary or slit die with pressure drops exce...

High-Pressure Study of the Methylsulfate and Tosylate Imidazolium Ionic Liquids

The considerable interest aroused in recent years by the unique properties and industrial applications of ionic liquids has given rise to the need for a detailed statement of the linkage between their molecular features and the observed macroscopic behavior. A combined experimental/computational approach to the study of ionic liquids is submitted here and applied to the relevant, nonhalogenated ionic liquids 1,3-dimethylimidazolium methylsulfate and 1-ethyl-3-methylimidazolium tosylate. To establish a reliable equation of state pertinent to these fluids, density data over wide pressure (0.1-60 MPa) and temperature (318.15-428.15 K) ranges, along with high pressure (1-70 MPa) viscosities and other selected ambient pressure properties were measured to assemble sufficient experimental information for the seek of predictive models for process design. A computational method based on ab initio and classical molecular dynamics yielded a deal of structural information, borne out by the experimental readings. Likewise, the predictive ability of the force field applied in molecular dynamics simulations was faced with the measured properties. The pictorial description of the selected ionic liquids reached this way may become widespread to other relevant examples in order to infer valuable structure/property relationships.

Capillary-Based Instrument for the Simultaneous Measurement of Solution Viscosity and Solute Diffusion Coefficient at Pressures up to 2000 bar and Implications for Ultrahigh Pressure Liquid Chromatography

An instrument based on the Poiseuille flow principle capable of measuring solution viscosities at high pressures has been modified to observe UV-absorbent analytes in order to allow for the simultaneous measurement of analyte diffusivity. A capillary time-of-flight (CTOF) instrument was used to measure the viscosity of acetonitrile-water mixtures in all decade volume percent increments and the corresponding diffusion coefficients of small aromatic molecules in these solvent mixtures from atmospheric pressure to 2000 bar (approximately 30,000 psi) at 25 degrees C. The instrument works by utilizing a relatively small pressure drop (<100 bar) across a fused-silica capillary which has both the inlet and outlet pressurized so that the average column pressure can be significantly elevated (up to 2000 bar). Measurements with this instrument agree with high-pressure viscosity data collected previously using a CTOF viscometer, as well as with literature values obtained with falling-body viscometers of the Bridgman design. It has been further determined that, for the small molecules included in this study, trends in solute diffusivity with respect to pressure follow the predictions of the Stokes-Einstein equation when the solvent viscosity is corrected as a function of pressure. Because the instrument described herein determines viscosity and diffusivity independently, the effect of pressure on analyte hydrodynamic radius can also be monitored. An analysis of ultrahigh pressure liquid chromatography (UHPLC) data was performed using the pressure-corrected diffusion coefficient of hydroquinone to demonstrate the effect of this phenomenon on the analysis of chromatographic performance.