Density and Viscosity Measurements of Dimethoxymethane and 1,2-Dimethoxyethane from 243 K to 373 K up to 20 MPa

Measurements of the density and viscosity of dimethoxymethane and 1,2-dimethoxyethane are reported over the temperature range from 243 K to 373 K and at pressures up to 20 MPa. The measurements were performed simultaneously using a vibrating-wire instrument operated in the forced mode of oscillation. The overall uncertainties of these results are 2.0% in viscosity and 0.2% in density. The measurements were correlated with a Tait-type equation for density and a hard-sphere model for viscosity. The maximum absolute deviation and the average absolute deviation (AAD) of the density measurements from the correlation for dimethoxymethane are 0.065% and 0.012%, respectively, and for 1,2-dimethoxyethane, are 0.16% and 0.044%. With regard to viscosity, the maximum absolute deviation and the AAD of the present results from the correlation for dimethoxymethane are 1.55% and 0.40%, respectively, and for 1,2-dimethoxyethane, are 1.05% and 0.26%. Comparisons of the experimental data and measurements from the literature with values calculated by the correlations at different temperatures and pressures are presented.     

Speed of Sound in Pure Water at Temperatures between 274 and 394 K and at Pressures up to 90 MPa

A newly designed experimental apparatus has been used to measure the speed of sound u in high-purity water on nine isotherms between 274 and 394 K and at pressures up to 90 MPa. The measurement technique is based on a traditional double-reflector pulse-echo method with a single piezoceramic transducer placed at unequal distances from two stainless steel reflectors. The transit times of an acoustic pulse are measured at a high sampling rate by a digital oscilloscope. The distances between the transducer and the reflectors were obtained at ambient temperature and pressure by direct measurements with a coordinate measuring machine. The speeds of sound are subject to an overall estimated uncertainty of 0.05 %. The acoustic data were combined with available values of density ρ and isobaric heat capacity c_p along one isobar at atmospheric pressure to calculate the same quantities over the whole temperature and pressure range by means of a numerical integration technique. These results were compared with those calculated from the IAPWS-95 formulation with corresponding relative deviations which are within 0.1%. Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A.     

Isochoric Heat Capacities of Propane + Isobutane Mixtures at Temperatures from 280 to 420 K and at Pressures to 30 MPa

The isochoric heat capacity (c_v) and pressure–volume–temperature-composition (pvTx) properties were measured for propane + isobutane mixtures in the liquid phase and in the supercritical region. The expanded uncertainty (k = 2) of temperature measurements is estimated to be ±13 mK, and that of pressure measurements is ±8 kPa. The expanded relative uncertainty for c_v is ±3.2% for the liquid phase, increasing to ±4.8% for near-critical densities. The expanded uncertainty for density is estimated to be ±0.16%. The present measurements for {xC₃H₈ +(1−x)i-C₄H₁₀} with x = 0.0, 0.498, 0.756, and 1.0, were obtained at 659 state points at temperatures from 270 to 420 K and at pressures up to 30 MPa. The experimental data were compared with a published equation of state. Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A.     

Thermal Conductivity of Carbon Dioxide–Methane Mixtures at Temperatures Between 300 and 425 K and at Pressures up to 12 MPa

The thermal conductivities of carbon dioxide and three mixtures of carbon dioxide and methane at six nominal temperatures between 300 and 425 K have been measured as a function of pressure up to 12 MPa. The measurements were made with a transient hot-wire apparatus. The relative uncertainty of the reported thermal conductivities at a 95% confidence level is estimated to be ±1.2%. Results of the low-density analysis of the obtained data were used to test expressions for predicting the thermal conductivity of nonpolar mixtures in a dilute-gas limit developed by Schreiber, Vesovic, and Wakeham. The scheme was found to underestimate the experimental thermal conductivity with deviations not exceeding 5%. The dependence of the thermal conductivity on density was used to test the predictive scheme for the thermal conductivity of gas mixtures under pressure suggested by Mason et al. and improved by Vesovic and Wakeham. Comparisons reveal a pronounced critical enhancement on isotherms at 300 and 325 K for mixtures with methane mole fractions of 0.25 and 0.50. For other states, comparisons of the experimental and predicted excess thermal conductivity contributions showed a smaller increase of the experimental data with deviations approaching 3% within the examined range of densities.     

Density and Viscosity of the 1-Methylnaphthalene+2,2,4,4,6,8,8-Heptamethylnonane System from 293.15 to 353.15 K at Pressures up to 100 MPa

The dynamic viscosity of the binary mixture 1-methylnaphthalene+2,2,4,4,6,8,8-heptamethylnonane was measured in the temperature range 293.15 to 353.15K (in progressive 10K steps) at pressures of 0.1, 20, 40, 60, 80, and 100MPa. The composition of the system is described by nine molar fractions (0 to 1 in 0.125 progressive steps). The density was measured at pressures from 0.1 to 60MPa in progressive 5 MPa steps. The measurements of are used to determine the excess viscosity ^E and the excess activation energy of flow G ^E as a function of pressure, temperature, and composition. Some models have been used to represent the viscosity of this binary mixture.     

Burnett PVT Measurements of Hydrogen and the Development of a Virial Equation of State at Pressures up to 100 MPa

PVT properties were measured for hydrogen by the Burnett method in the temperature range from 353 K to 473 K and at pressures up to 100 MPa. In the present Burnett method, the pressure measurement was simplified by using an absolute pressure transducer instead of a differential pressure transducer, which is traditionally used. The experimental procedures become easier, but the absolute pressure transducer is set outside the constant temperature bath because of the difficulty of its use in the bath, and the data acquisition procedure is revised by taking into account the effects of the dead space in the absolute pressure transducer. The measurement uncertainties in temperature, pressure, and density are 20 mK, 28 kPa, and 0.07 % to 0.24 % (k = 2), respectively. Based on the present data and other experimental data at low temperatures, a virial equation of state (EOS) from 220 K to 473 K and up to 100 MPa was developed for hydrogen with uncertainties in density of 0.15 % (k = 2) at P ≤ 15 MPa, 0.20 % at 15 MPa < P ≤ 40 MPa, and 0.24 % at P > 40 MPa, and this EOS shows physically reasonable behavior of the second and third virial coefficients. Isochoric heat capacities were also calculated from the virial EOS and were compared with the latest EOS of hydrogen. The calculated isochoric heat capacities agree well with the latest EOS within 0.5 % above 300 K and up to 100 MPa, while at lower temperatures, as the pressure increases, the deviations become larger (up to 1.5 %).     

History Dependence of Turbulence Generated by a Vibrating Wire in Superfluid 4He at 1.5 K

We report on the onset of turbulence in normal and superfluid ⁴He using several 13.5 μm diameter vibrating wire resonators placed in a cell, filtered from the surrounding helium bath. We measured the force-velocity characteristics of the wires in normal and superfluid helium over a velocity range up to several meters per second. The transition from laminar to turbulent behavior can be clearly identified. Surprisingly we find that, depending on the cooling history, turbulence in the superfluid does not always develop fully.     

Estimation of solubility and thermodynamic characteristics of solvation of radon in deuterated water at 0.1 MPa and 278–318 K

The concentration of Rn in saturated solution in D₂O at 101 325 Pa and 278.15–318.15 K (at 5 K interval) was estimated by the Karapet’yants method of comparative calculation from original and published data on the solubility of noble gases He-Xe in H/D water isotopomers and of Rn in H₂O. Thermodynamic functions of Rn solvation (Δ_sol G ⁰, Δ_sol H ^∞, Δ_sol S ⁰, and Δ_sol C _p ^∞ ) in H₂O and D₂O and the corresponding H/D isotope effects were calculated by the original method. The characteristics obtained for the D₂O-Rn system are consistent with the previously found trends in variation of thermodynamic isotope effects of solvation of noble gases (He-Xe) in aqueous solution with increasing temperature.     

Volumetric and Acoustic Properties for Binary Mixtures of Dipropylene Glycol Monopropyl Ether with Alkylamines at Temperatures Between 288.15 K and 308.15 K

The densities, ρ, and speeds of sound, u, have been measured as a function of composition for binary liquid mixtures of dipropylene glycol monopropyl ether (DPGMPE) with n-butylamine (BA), dibutylamine (DBA), and tributylamine (TBA) at (288.15, 293.15, 298.15, 303.15, and 308.15) K and atmospheric pressure using an Anton Paar DSA-5000 instrument. The ρ and u values were used to calculate excess molar volumes, V ^E, deviations from the ideal behavior of the thermal expansion coefficient, α ^E, and the isentropic compressibilities, Δκ _S . Moreover, the apparent molar volume , and apparent molar compressibility , of the components have been calculated at infinite dilution. The Jouyban–Acree model is used to correlate the experimental values of density and ultrasonic speed at different temperatures.     

Measurements of Vapor Pressures from 280 to 369 K and (p, ρ, T) Properties from 340 to 400 K at Pressures to 200 MPa for Propane

Measurements of (p, ρ, T) properties for compressed liquid propane have been obtained by means of a metal-bellows variable volumometer at temperatures from 340 to 400 K at pressures up to 200 MPa. The volume- fraction purity of the propane sample was 0.9999. The expanded uncertainties (k = 2) of temperature, pressure, and density measurements have been estimated to be less than 3 mK; 1.5 kPa ( MPa), 0.06% (7 MPa MPa), 0.1% (50 MPa MPa) , and 0.2% (p>150 MPa); and 0.11%, respectively. Four (p, ρ, T) measurements at the same temperatures and pressures as literature values have been conducted for comparisons. In addition, vapor pressures were measured at temperatures from 280 to 369 K. Furthermore, comparisons of available equations of state with the present measurements are reported.Paper presented at the 17th European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak Republic.     

Measurement of the (p, \rho,T) Properties for Pure Hydrocarbons at Temperatures up to 600 K and Pressures up to 200 MPa

The data available for the thermodynamic properties of propane, \(n\) -butane, and isobutane at temperatures above 440 K are outdated and show significant discrepancies with each other. The ambiguity associated with these data could be limiting to the development of any understanding related to the effects of mixing of these substances with other materials such as \(\text{ CO}_{2}\) , ammonia, and non-flammable or lower-flammable HFC refrigerants. In this study, the (p, \(\rho \) , T) properties of propane, \(n\) -butane, and isobutane were measured at temperatures ranging from (360 to 600) K and pressures ranging from (50 to 200) MPa. Precise measurements were carried out using a metal-bellows variable volumometer with a thermostatted air bath. The expanded uncertainties \((k = 2)\) in the temperature, pressure, and density measurements were estimated to be \(<\) 5 mK, 0.02 MPa, and 0.88 kg  \(\cdot \)  m \(^{-3}\) ( \(T\le 423\)  K, \(p<100\)  MPa), 0.76 kg  \(\cdot \)   \(\text{ m}^{-3}\) ( \(T\le 423\)  K, \(p\ge 100\)  MPa), 0.76 kg  \(\cdot \)   \(\text{ m}^{-3}\) ( \(T>423\)  K, \(p < 100\)  MPa), and 2.94 kg  \(\cdot \)   \(\text{ m}^{-3}\) ( \(T>423\)  K, \(p \ge 100\)  MPa), respectively. The data obtained throughout this study were systematically compared with the calculated values derived from the available equations of state. These models agree well with the measured data at higher temperatures up to 600 K, demonstrating their suitability for an effective and precise examination of the mixing effects of potential alternative mixtures.     

pρT Measurements of Polyethylene Glycol Dimethylethers Between 278.15 and 328.15 K at Pressures to 12 MPa

In this paper we present a new experimental apparatus designed to measure pressure–density–temperature (pT ) properties with a high-pressure vibrating tube densimeter. Data reliability has been verified by comparing our experimental results for methanol, n-heptane, toluene, and HFC-134a with literature data. In this work we also report new experimental densities from 278.15 to 328.15 K, and up to 12 MPa, of triethylene glycol dimethylether (TrEGDME) and tetraethylene glycol dimethylether (TEGDME). The isobaric thermal expansion coefficients, isothermal compressibility, and internal pressure have been calculated. The dependence of these properties on the length of polyethylene glycol dimethylether, CH₃O–((CH₂)₂O) _n –CH₃, is analyzed.     

Thermal-Conductivity Measurements of Aqueous Orthophosphoric Acid Solutions in the Temperature Range from (293 to 400) K and at Pressures up to 15 MPa

A new improved guarded parallel-plate thermal-conductivity cell for absolute measurements of corrosive (chemically aggressive) fluids under pressure has been developed. Using the new modified guarded parallel-plate apparatus the thermal conductivity of aqueous orthophosphoric acid solutions was measured over the temperature range from (293 to 400) K and pressures up to 15 MPa. Measurements were made for three compositions of \(\text {H}_{3}\text {PO}_{4}\) (8 mass%, 15 mass%, and 50 mass%) along three isobars of (0.101, 5, and 15) MPa. The combined expanded uncertainty of the thermal-conductivity \((\lambda )\) measurements at the 95 % confidence level with a coverage factor of \(k=2\) is estimated to be 2 %. The uncertainties of the temperature, pressure, and concentration measurements were 15 mK, 0.05 %, and 0.01 %, respectively. The temperature, concentration, and pressure dependences of the thermal conductivity of the solution were studied. The measured values of thermal conductivity were compared with the available reported data and the values calculated from various correlation and prediction models. A new wide-range correlation model (extended Jones–Dole type equation with pressure-dependent coefficients) for the \(\text {H}_{3}\text {PO}_{4}\) (aq) solution was developed using the present experimental data.     

Micromechanical properties of grain boundaries and triple junctions in polycrystalline metal exhibiting grain-boundary sliding at 293 K

The mechanical properties of grain boundaries (GBs) and the development of grain-boundary sliding (GBS) were studied in the pure Zn using precision microindentation technique, optical, electron and atomic-force microscopy. Results have shown the different dependencies of the microhardness values on the indentation depth for GBs and individual grains. When the size of the plastic zone around the imprint was comparable to the grain size, GBs acted as barriers for dislocation sliding bands and twins. With applying the higher load, more grains were involved in the process of deformation, but microhardness did not increase. That was explained by the activation of GBS, leading to the relaxation processes. In its turn, the microhardness values measured at low loads in the vicinity to GBs and triple junctions (TJs) were higher than those measured in the grain interior. Thus, movement of the ensemble of defects to the GBs during microindentation is the activating factor for GBS in polycrystalline Zn. At the same time, during spreading of the deformation at low loads in the vicinity to GBs the activation of GBS was not observed.     

Microstructure and mechanical properties of high purity nanostructured titanium processed by high pressure torsion at temperatures 300 and 77 K

Several structural states of nanostructured high purity Ti with average grain size down to 100 nm were achieved by high pressure torsion (HPT) at temperatures 300 and 77 K. As a result of HPT processing, changes of crystallographic texture, of grain and crystallite size, and of the dislocation density have been measured and analyzed. Mechanical properties of the nanostructured Ti were studied by uniaxial compression at temperatures 300, 77, and 4.2 K. The texture components indicate simple shear deformation arising from HPT. With subsequent compression, the yield strength appears to be governed by the grain size rather than by crystallite size, dislocation density, and/or impurity content. Considerable changes of texture were observed after low temperature compressive deformation indicating that twinning markedly contributes to plasticity.     

<Emphasis Type="Italic">PVT</Emphasis> Relationships of Binary Mixtures of Indole with 2-Methylnaphthalene and Biphenyl at 333.15 K and Pressures up to 270 MPa

PVT relationships of two binary mixtures of indole with 2-methylnaphthalene and with biphenyl have been measured at 333.15 K and at pressures up to 270 MPa or up to near the freezing pressure of each mixture. The compositions in mole fraction of indole were set to be 0.2500, 0.5000, and 0.7500 for both systems. PVT relationships of indole (at 343.15 K and 353.15 K), 2-methylnaphthane (at 333.15 K and 343.15 K), and biphenyl (at 353.15 K and 363.15 K) under pressure and those for the binary mixtures at 0.1 MPa in the temperature range from 293.15 K to 363.15 K were also measured. PVT data were analyzed with the use of the Tait equation and Carnahan–Starling–van der Waals (CS–vdW) equation. It was found that both the equations can be used to represent the experimental PVT relationships for the pure compounds and the binary mixtures with an average absolute deviations of 0.04% for the Tait equation and 0.29% for the CS–vdW equation. As for mixture density calculations with the CS–vdW equation, the effect of mixing rules was investigated.     

Experimental Determination of Densities and Isobaric Vapor–Liquid Equilibria of Methyl Acetate and Ethyl Acetate with Alcohols (C3 and C4) at 0.3 MPa

The densities and excess volumes were determined at 298.15 K for the methyl acetate + 1-propanol, methyl acetate + 1-butanol, and ethyl acetate + 1-butanol mixtures. The vapor–liquid equilibria data at 0.3 MPa for these binary systems were obtained using a stainless steel equilibrium still. The activity coefficients were obtained from the experimental data using the Hayden and O’Connell method and the Yen and Woods equation. The binary systems in this study showed positive deviations from ideality. The experimental VLE data were verified with the point-to-point test of van Ness using the Barker routine and the Fredenslund criterion. The different versions of the UNIFAC and the ASOG group contribution models were applied.     

Transport properties of nonelectrolyte liquid mixtures. VIII. Viscosity coefficients for toluene and for three mixtures of toluene + hexane from 25 to 100°C at pressures up to 500 MPa

Viscosity coefficients measured using a two-coil self-centering falling-body viscometer are reported for toluene and three binary mixtures of toluene + n-hexane at 25, 50, 75, and 100°C at pressures up to 500 MPa. The data for a given composition at different temperatures and pressures are correlated very satisfactorily by a plot of reduced viscosity ^* versus log V, where V=V·V ₀(T_R)/V₀(T) and V ₀ represents a characteristic volume. The binary mixture data are well represented by the Grunberg and Nissan equation with a mixing parameter which is pressure dependent but composition and temperature independent.