High-pressure Viscosity Research Articles

Revisiting the ASME Pressure-Viscosity Report Using the Tait-Doolittle Correlations

Abstract The ASME Pressure-Viscosity Report was a seminal publication on high pressure-viscosity and density supervised by the ASME Research Committee on Lubrication, sponsored by dozens of industries, and undertaken by Harvard University using high-pressure equipment developed by Prof. P. W. Bridgman. The resulting measurements of the “Viscosity and Density of Over 40 Lubricating Fluids of Known Composition at Pressures to 150,000 psi (1034 MPa) and Temperatures to 425 °F (218.3 °C/491.5 K)” should have become an invaluable reference to tribologists around the world. The present work revisits that monumental effort to distill the results into an established equation of state using modern computer software. The authors used curve-fitting techniques to fit measured density and viscosity data to the parameters of the Tait-Doolittle equation for use in further tribological modeling. This information will help a new generation of engineers to model the piezoviscous properties of lubricant base-stocks in diverse tribological applications.

Viscosity and degradation controlled injectable hydrogel for esophageal endoscopic submucosal dissection

Endoscopic submucosal dissection (ESD) is a common procedure to treat early and precancerous gastrointestinal lesions. Via submucosal injection, a liquid cushion is created to lift and separate the lesion and malignant part from the muscular layer where the formed indispensable space is convenient for endoscopic incision. Saline is a most common submucosal injection liquid, but the formed liquid pad lasts only a short time, and thus repeated injections increase the potential risk of adverse events. Hydrogels with high osmotic pressure and high viscosity are used as an alternate; however, with some drawbacks such as tissue damage, excessive injection resistance, and high cost. Here, we reported a nature derived hydrogel of gelatin-oxidized alginate (G-OALG). Based on the rheological analysis and compare to commercial endoscopic mucosal resection (EMR) solution (0.25% hyaluronic acid, HA), a designed G-OALG hydrogel of desired concentration and composition showed higher performances in controllable gelation and injectability, higher viscosity and more stable structures. The G-OALG gel also showed lower propulsion resistance than 0.25% HA in the injection force assessment under standard endoscopic instruments, which eased the surgical operation. In addition, the G-OALG hydrogel showed good in vivo degradability biocompatibility. By comparing the results acquired via ESD to normal saline, the G-OALG shows great histocompatibility and excellent endoscopic injectability, and enables create a longer-lasting submucosal cushion. All the features have been confirmed in the living both pig and rat models. The G-OALG could be a promising submucosal injection agent for esophageal ESD.

Probing the high-pressure viscosity of hydrocarbon mixtures using molecular dynamics simulations.

Computational predictions of the high-pressure viscosity of hydrocarbon mixtures could help to accelerate the development of fuels and lubricants with improved performance. In this study, we use molecular dynamics simulations to study the viscosity and density of methylcyclohexane, 1-methylnaphthalene, and their binary mixtures at 323 K and pressures of up to 500 MPa. The simulation results are in excellent agreement with previous experiments available up to 100 MPa for both pure compounds (200 MPa for 1-methylnaphthalene) and the binary mixtures. For 1-methylnaphthalene, the viscosity initially increases slower-than-exponential with pressure before it reaches an inflection point and then increases faster-than-exponential. The inflection point (300 MPa) occurs at a pressure slightly below the one at which 1-methylnaphthalene is expected to enter the supercooled phase (400 MPa). For methylcyclohexane, the increase in viscosity with pressure is slower-than-exponential over the entire pressure range studied. The binary mixtures show intermediate pressure-viscosity responses between the two pure cases. The applicability of equations commonly used to describe the pressure dependence of viscosity, as well as the viscosity of binary mixtures, is evaluated against the computational predictions.

Design of a high-pressure viscosity-measurement system using two pressure balances

In this paper, a new high-pressure viscosity measurement system using a capillary method is reported. In this system, two pressure balances are used to generate stable pressure and flow field in the capillary. The volumetric flow rate was measured by calculating the change in the piston fall rate. To check the effectiveness of the method, the viscosity of bis(2-ethylhexyl) sebacate was measured at pressures of up to 200 MPa. Differential pressure and volumetric flow rate had a linear relationship at all temperature and pressure conditions, indicating that the Hagen–Poiseuille law can be applied in this method. The viscosity–pressure dependence is in agreement with other published reports. Thus, we confirmed that the newly developed high-pressure viscosity measurement system can accurately evaluate the pressure dependence of viscosity.

Isotope effects on the high pressure viscosity of liquid water measured by differential dynamic microscopy

Differential dynamic microscopy is performed in diamond anvil cells to measure the viscosity of water along the 24 °C isotherm to high pressure by the determination of the tracer diffusion coefficient of monodisperse silica spheres of known diameter and the application of the Stokes–Einstein–Sutherland equation. This technique allows liquid samples to be compressed to greater pressure prior to freezing than with other viscometry methods. The highest-pressure measurement was made at 1.67 GPa, considerably deeper into the supercompressed regime than previously reported. The effect of the isotopic composition is investigated with samples of normal water, heavy water, and partially deuterated water. When data below 0.25 GPa are excluded, a free volume model fits the observed viscosities well, yielding a theoretical glass transition density close to that observed in very-high-density amorphous ice. The improved fit above 0.25 GPa coincides with the loss of other anomalous behaviors in liquid water caused by hydrogen bonding and represents a transition to properties closer to those of a simple liquid.

Liquid viscosities of ethyl caprylate and ethyl caprate at elevated temperatures and pressures

In this work, the high-pressure liquid viscosities of ethyl caprylate and ethyl caprate were measured at the temperatures from 303 K to 362 K and pressures up to 30 MPa. The measurements were carried out based the falling-cylinder viscosity measurement system which was established in our laboratory. The combined expanded relative uncertainty of the present measurement was <0.03 with a confidence level of 0.95. The high-pressure viscosity values were correlated with Andrade-Tait equation. The average relative deviation between experimental data and calculated results from Andrade-Tait equation for ethyl caprylate and ethyl caprate was 0.38% and 0.73%, respectively. The maximum relative deviation was 1.32% and 1.96%, respectively.

High-Pressure Density, Viscosity, and Modeling of Mixtures of a Poly(α-olefin) Base Oil Lubricant with Polymeric Additives

Volumetric properties and viscosity of mixtures of a synthetic poly(α-olefin) base oil with polymethacrylate-based polymeric additives have been studied. Two different polymeric additives were eval...

Study on Relations of High-Pressure Viscosity Properties of Various Viscosity Index Improver-Blended Oils and Dissolved State of Polymer Coils, and Their Behavior

Study on Relations of High-Pressure Viscosity Properties of Various Viscosity Index Improver-Blended Oils and Dissolved State of Polymer Coils, and Their Behavior

A novel approach towards sustainable electrical discharge machining of metal matrix composites (MMCs)

It is a daunting challenge to improve the sustainability of electrical discharge matching (EDM) as well as to make the process environmentally friendly. This paper carried out investigations into the role of steam as a dielectric medium during sink (EDM) of aluminum-based metal matrix composite (MMC) and critically compares the outcome with that of widely used hydrocarbon-based dielectrics such as kerosene in terms of output parameters, positive environmental aspect, and cost-effectiveness. The output parameters such as recast layer, material removal rate (MRR), and machined surface characteristics were analyzed in details. The recast layer obtained upon steam dielectric EDM was significantly improved by 37.15% in terms of thickness, bonding with base metal as well as structure and morphology. This favorable development was attributed towards high temperature, low heat spark material erosion, and low conductivity of steam as a dielectric medium. The machined surface upon steam dielectric EDM apparently contained machined debris rather than solidified molten workpiece material and contributed towards minimum roughness by 1.5 times due to high temperature, high pressure, and low viscosity of the steam. It is found that the ongoing cost of sink EDM can be reduced to one-fifth if the hydrocarbon-based dielectric is replaced by steam.

Pressure Temperature Superposition Graph of Lubricant High-Pressure Viscosity

Pressure Temperature Superposition Graph of Lubricant High-Pressure Viscosity

High-Pressure Viscosity Measurements for the Binary Mixture HFE-7500 + Diisopropyl Ether

In this work, high-pressure viscosity measurements for seven compositions of the binary mixture (x) HFE-7500 + (1 – x) diisopropyl ether were carried out. A set of 163 points have been measured cov...

High pressure viscosity behaviour of tris(2-ethylhexyl) trimellitate up to 150 MPa

This article presents a study on the viscous behaviour at high pressure of a synthetic oil, tris(2-ethylhexyl) trimellitate (TOTM). This fluid is being recommended as potential industrial reference material for high viscosity-high pressure measurements. Here we report new experimental viscosity values for TOTM at temperatures from 278.15 K to 373.15 K and at pressures to 150 MPa with a maximum viscosity of 2570 mPa s. The measurements have been performed using a high pressure falling-body apparatus and a Couette rotational viscometer. The experimental values obtained in this work are included in the database of a multinational project used recently to develop a reference correlation for TOTM (Wakeham et al., 2017). The universal viscosity-pressure coefficient of this fluid has been evaluated and compared with other oils, finding that it is close to the literature values of mineral oils. Moreover, we perform an analysis of the dependency of viscosity on pressure and temperature based on the density scaling concept.

High Pressure Volumetric Properties and Viscosity of Base Oils Used in Automotive Lubricants and Their Modeling

Temperature and pressure effects on density and viscosity are reported for six base oils consisting of four mineral oils and two synthetic oils composed of poly(α-olefins). Using a variable-volume view cell, density data were collected at 298, 323, 348, 373, and 398 K from 10 to 40 MPa. The data were then fit to the Sanchez–Lacombe equation of state and used to determine isothermal compressibility, isobaric thermal expansion coefficient, and internal pressure. Compressibility and internal pressure were found to vary based on composition, specifically with cycloalkane content. Viscosity data were collected as a function of temperature, pressure, and rotational speed using a custom-built high pressure rotational viscometer. Data were collected at 298, 323, 348, and 373 K from 10 to 40 MPa at rotational speeds of 300–800 rpm. A free-volume model was used to model the viscosity and relate the viscous effects to density.

各種粘度指数向上剤添加油の高圧粘度特性とポリマー挙動の関係に関する研究（第1報） ―高圧粘度の測定と圧力-粘度係数計算式の導出―

各種粘度指数向上剤添加油の高圧粘度特性とポリマー挙動の関係に関する研究（第1報） ―高圧粘度の測定と圧力-粘度係数計算式の導出―

Presenting a new predictive viscosity model based on virial-like equations of state for monatomic fluids

ABSTRACTWe present a new model using virial-like equations of state (EOSs) to calculate the viscosity of pure monatomic fluids that are applicable to liquid, gas, and supercritical regions. The viscosity model has been constructed according to the similarity between P–V–T (pressure–volume–temperature) and T–μ–P (temperature–viscosity–pressure) relationship. Over an extensive pressure and temperature ranges, the obtained results are comparable with the experimental data. The average range of application of this model is for reduced temperatures between 0.5 and 43.5 and for reduced pressures between 0.1 and 78.4. The obtained results are consistent with the experimental data, except in the vicinity of the critical point, the average absolute deviation percent is 2.5 compared with the experimental data. Using the temperature and pressure, calculation of fluid viscosity is straightly possible by applying this model. Based on the findings of this paper, prediction of high-pressure liquid and far-supercritical viscosities of a fluid using low-pressure liquid and gaseous EOSs is possible.

In situ observation of gelation of methylcellulose aqueous solution with viscosity measuring instrument in the diamond anvil cell

Gelation of methylcellulose aqueous solution was investigated by a high-pressure viscosity measurement device which consisted of diamond anvil cell, microscope and CCD. And the temperature and pressure dependence of the viscosity of methylcellulose aqueous solution was measured utilizing a rolling-ball technique. The results showed that sol-gel thermal transition of methylcellulose solution occurred at the temperature of 53 °C under atmospheric pressure. Upon compression, it was indicated that the viscosity showed a dramatic change in the vicinity of the pressure of 500 MPa. Parabolic phase diagram of methylcellulose aqueous solution was constructed, and it showed that the melting point was an increasing function of pressure at the first stage and an decreasing function of pressure at the final stage. The mechanism of sol-gel transformation of methylcellulose aqueous solutions was also discussed, it might be assumed that both hydrogen and hydrophobic bonds were involved with the gel formation in the case of methylcellulose aqueous solution.

Viscosity-pressure dependence for nanostructured ionic liquids. Experimental values for butyltrimethylammonium and 1-butyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide

Abstract New measurements of the viscosity of three ionic liquids (ILs), 1-ethyl-3-methylimidazoliumethylsulfate, 1-butyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide and butyltrimethylammonium bis(trifluoromethylsulfonyl)imide were carried out in two laboratories by using three different devices. The viscosity of these ionic liquids was measured at atmospheric pressure by means of a vibrating wire viscometer and a rotational viscometer with relative expanded uncertainties (k = 2) of 1.5% and 1%, respectively. Viscosity behaviour of the last two ILs at high pressure was studied with a falling body viscometer with a relative expanded uncertainty (k = 2) of 3.5%. In addition, the universal pressure-viscosity coefficient was calculated for these fluids, as well as for 14 ionic liquids studied in the literature. Taking into account the high pressure viscosity behaviour of 30 ILs it have been concluded that for similar viscosity grade ILs based on tris(pentafluoroethyl)trifluorophosphate anion present the highest film thickness capacity.

Study on Relations of High-Pressure Viscosity Properties and the Polymer Behavior of Various Viscosity Index Improver-Blended Oil (Part 2)

Study on Relations of High-Pressure Viscosity Properties and the Polymer Behavior of Various Viscosity Index Improver-Blended Oil (Part 2)

High pressure metrology for industrial applications

To meet the needs of industries using high pressure technologies, in traceable, reliable and accurate pressure measurements, a joint research project of the five national metrology institutes and the university was carried out within the European Metrology Research Programme. In particular, finite element methods were established for stress–strain analysis of elastic and nonlinear elastic–plastic deformation, as well as of contact processes in pressure-measuring piston-cylinder assemblies, and high-pressure components at pressures above 1 GPa. New pressure measuring multipliers were developed and characterised, which allow realisation of the pressure scale up to 1.6 GPa. This characterisation is based on research including measurements of material elastic constants by the resonant ultrasound spectroscopy, hardness of materials of high pressure components, density and viscosity of pressure transmitting liquids at pressures up to 1.4 GPa and dimensional measurements on piston-cylinders. A 1.6 GPa pressure system was created for operation of the 1.6 GPa multipliers and calibration of high pressure transducers. A transfer standard for 1.5 GPa pressure range, based on pressure transducers, was built and tested. Herewith, the project developed the capability of measuring pressures up to 1.6 GPa, from which industrial users can calibrate their pressure measurement devices for accurate measurements up to 1.5 GPa.

Glass Transition Temperature and Density Scaling in Cumene at Very High Pressure.

We present a new method that allows direct measurements of the glass transition temperature T_{g} at pressures up to 4.55GPa in the glass-forming liquid cumene (isopropylbenzene). This new method uses a diamond anvil cell and can measure T_{g} at pressures of 10GPa or greater. Measuring T_{g} at the glass→liquid transition involves monitoring the disappearance of pressure gradients initially present in the glass, but also takes advantage of the large increase in the volume expansion coefficient α_{p} at T_{g} as the supercooled or superpressed liquid is entered. Accurate T_{g}(P) values in cumene allow us to show that density scaling holds along this isochronous line up to pressures much higher than any previous study, corresponding to a density increase of 29%. Our results for cumene over this huge compression range yield ρ^{γ}/T=C, where C is a constant and where γ=4.77±0.02 for this nonassociated glass-forming system. Finally, high-pressure cumene viscosity data from the literature taken at much lower pressures and at several different temperatures, corresponding to a large dynamic range of nearly 13 orders of magnitude, are shown to superimpose on a plot of η vs ρ^{γ}/T for the same value of γ.