Solid hydrogen: Ground-state energy,pressure, and compressibility

The ground-state energy, the pressure, and the compressibility of solid molecular hydrogen is calculated by means of a modified Brueckner theory. The Bethe-Goldstone equation is solved to give the reaction matrix or an effective interaction in coordinate space; the ground-state energies for normal hydrogen and deuterium are calculated. Also, the pressure and the compressibility is estimated from the dependence of the ground-state energy on density or molar volume. Both hcp and fcc structures are considered. Theoretical results for the ground-state energy per particle are –82 K for solid hydrogen at a molar volume of 22 cm³/mole and –135 K for solid deuterium at a molar volume of 19 cm³/mole. The corresponding experimental results are –92 and –138 K, respectively. We obtain zero pressure for solid hydrogen at a molar volume of 22.45 cm³/mole and for solid deuterium at a molar volume of 19.2 cm³/mole. The corresponding experimental results are 22.65 and 19.56 cm³/mole, respectively. Theoretical results for the compressibility at zero pressure are 5.3×10^–4 atm^–1 for solid hydrogen and 2.6×10^–4 atm^–1 for solid deuterium. The corresponding experimental results are 4.9×10^–4 and 3.0×10^–4 atm^–1, respectively. The agreement with experimental results is reasonably good since higher order cluster terms are not included in this first approximation.     

Experimental investigation of the temperature dependence of the accommodation coefficients for the gases He,Ne, Ar,and Xe on a Pt surface

This paper presents measurements of accommodation coefficients for the gases He, Ne, Ar, and Xe on a Pt surface in the temperature range 100–500°K. An improved unsteady hot-wire method at low pressure is used.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 34, No. 5, pp. 880–884, May, 1978.     

Experimental research on specific volumes of rubidium and potassium vapors

Results are reported of an experimental study of superheated rubidium vapor in the temperature range 1450–2000 K and pressure range 1.7–5.2 MPa and potassium in the range 1500–2100 K and 1.4–4.0 MPa. The experiments have been performed with an apparatus adaoted to implement a modified constant-volume piezometer technique, where the sensing element of a pressure transducer represented by a diaphragm is placed in a low-temperature zone. A dosing device is described which permits the performance of accurate measurements of the mass of the metal in the piezometer chamber. The present results are in good agreement with those reported by other investigators in the overlaping temperature and pressure ranges.     

Measurement of the density of atmospheric air with a laser refractometer

The results are presented of air density measurements in the pressure range 410 to 820 mm Hg. The measurements were made with a differential laser refractometer. The error in the density measurements was about 1.10^–5. An evaluation of the errors is made, in comparison with those in weighing and calculation methods.Translated from Izmeritel'naya Tekhnika, No. 3, pp. 34–35, March, 1995.     

Dynamic viscosity of aqueous solutions of hydrazine with high state parameters

We report the results of measurements of the dynamic viscosity of aqueous solutions of hydrazine with a molar concentration of water ranging from 10 to 90%, in the temperature interval 293–558.4 K and the pressure interval 0.101–58.86 MPa.Translated from Izmeritel'naya Tekhnika, No. 9, pp. 43–45, September, 1994.     

PVT Measurements on tetrafluoroethane (R134a) along the vapor-liquid equilibrium boundary between 288 and 373 K and in the liquid state from the triple point to 265 K

For the investigations of the gas-liquid phase equilibria, a new apparatus has been developed capable of simultaneously determining the pressure and the liquid and vapor densities using Archimedes' principle. The relative measurement uncertainties of the liquid and vapor densities of R134a (purity, 99.999%) at 313 K are 2×10^–4 and 7×10^–4, respectively (95% confidence level). For the measurements in the liquid region along nine quasi-isochores at pressures up to 5 MPa, an isochoric apparatus was used. The relative measurement uncertainty ofpv/(RT) is less than 1×10^–3. In addition to the investigation of the (p, v, T) properties, the temperature and pressure at the triple point and the vapor pressure between the triple point and 265 K were measured. On the basis of these data, a vapor pressure correlation has been developed that reproduces the measured vapor pressures within the uncertainty of measurement. The results of our measurements are compared with a fundamental equation for R134a, which is based on the measurements of other research groups.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

Density of organic binary mixtures from equilibrium measurements

A reduction model for equilibrium measurements data (pressure–temperature–weight data) was developed. The model allows indirect measurements of the refrigerant concentration at the liquid and the gas phases and the solution density. The reduction model was validated by both comparing the obtained pressure–temperature–concentration relation at equilibrium conditions and solution densities with experimentally direct measurements carried out by Kriebel and Loffler [M. Kriebel, J. Loffler, Therodynamische eigenschaften des binary systems difluormono-chlormethan (R22) – tetraäthylenglykoldimethyläther (E181), Kältetechnik 17 (1965) 266–271] (up to 80 °C) and by us (up to 120 °C) over a wide range of pressure and temperature.     

The thermal conductivity of the mixtures of liquid hydrocarbons at pressures up to 400 MPa

The paper presents the results of measurements of the thermal conductivity of three binary mixtures of normal heptane and 2,2,4-trimethyl pentane. The measurements were carried out within the temperature range 308–359 K and over the pressure range 0.1–410 MPa with a transient hot-wire instrument. The experimental data have an estimated uncertainty of ±0.3%. The experimental data have been represented by simple polynomials along isotherms as a function of pressure for each composition for the purpose of interpolation. However, an alternative scheme of representation, based upon an heuristic extention of the hard-sphere theory, is shown to give a much more concise representation capable of extrapolation. Indeed, a procedure for the prediction of the thermal conductivity of the mixtures, based on the same theory, which uses no information derived from the present measurements, is shown to yield results of an accuracy sufficient for many purposes.     

Thermal conductivity,heat capacity,and thermal diffusivity of selected commercial AlN substrates

The thermal transport properties of four commercially available AlN substrates have been investigated using a combination of steady-state and transient techniques. Measurements of thermal conductivity using a guarded longitudinal heat flow apparatus are in good agreement with published room temperature data (in the range 130–170 W · m^–1 · K^–1). Laser flash diffusivity measurements combined with heat capacity data yielded anomalously low results. This was determined to be an experimental effect for which a method of correction is presented. Low-temperature measurements of thermal conductivity and heat capacity are used to probe the mechanisms that limit the thermal conductivity in AlN.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Energy required to fill a channel with polymer melt under pulsating pressure

Results are shown of measurements which have been made for the purpose of determining the work of external forces required to fill a rectangular channel with polymer melt under constant pressure or periodically variable pressure (at a frequency of 6–17 Hz). It has been established that filling a channel under pulsating pressure requires 1.5–1.7 times less energy than filling it under steady flow conditions.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 25, No. 6, pp. 1095–1100, December, 1973.     

Ultrasonic speeds and densities of poly(dimethylsiloxane) (viscosity grades 30 and 50×10−4 m · s−1) at 298.15, 303.15, and 308.15 K under high pressures

The ultrasonic speeds and densities of poly(dimethylsiloxane), viscosity grades 30 and 50×10^–4 m · s^–1 at 298.15 K, were measured at 298.15, 303.15, and 308.15 K. The measurements were carried out using new apparatuses, one for measurement of the speed under pressures up to 200 MPa and another for measurement of the density under pressures up to 100 MPa. The former is constructed with a sing-around technique of the fixed-path type operated at a frequency of 2 MHz, and the latter is a dynamic bellows piezometer. The probable uncertainty in the present results is within ±0.23% for speed and ±0.19% for density for all the experimental conditions. The ultrasonic speed in these fluids at first increases rapidly with pressure and then indicates a mild rise in the highpressure region. Similar pressure effects are observed for the density. The relationship between the speed and the density satisfied a first-order function well. The isentropic compressibility, derived from the speed and density, also showed a large pressure effect. The values and its pressure effects seemed almost independent of the viscosity of poly(dimethylsiloxane).     

The thermal conductivity of xylene isomers in the temperature range 290–360 K

New absolute measurements of the thermal conductivity of the three xylene isomers are reported. The measurements have been carried out in the temperature range 290–360 K, at atmospheric pressure, in a transient hot-wire instrument. The accuracy of the measurements is estimated to be ±0.5%. The measurements presented in this paper have been used in conjuction with our earlier reported measurements of liquid benzene and toluene, at atmospheric pressure, to develop a consistent theoretically based predictive scheme for the thermal conductivity of these five aromatic hydrocarbons. The proposed scheme, containing just one parameter characteristic of each fluid, permits the prediction of the thermal conductivity of the five aromatic hydrocarbons in the temperature range 290–360 K and at pressures up to 350 MPa, with an accuracy of ±2.5%.     

Experimental Investigations of Phase Equilibria in Binary Liquid Immiscible Alloys

Electroconductivity measurements for liquid metal (Tl, In)–chalcogen (Se, Te) alloys were performed in concentration range of their miscibility gaps. The experiments have been carried out under excess pressure of argon gas (up to 50 MPa) at temperatures up to 1200 K. Many-sectional measuring cell allows simultaneous determination of the electroconductivities of both separated liquids in entire range of the miscibility gap. The liquid–liquid coexistence curves for Tl–Se, Tl–Te, In–Se, and In–Te systems were constructed and critical point data were evaluated. The critical indices were also estimated. The results are analyzed in comparison to available data for fluid metals in vicinity of the liquid–vapor critical point.     

Densities,Viscosities, and Refractive Indices of Mixtures of Hexane with Cyclohexane,Decane, Hexadecane,and Squalane at 298.15 K

Densities, ρ, viscosities, η, and refractive indices, n_D, have been measured as a function of composition for binary mixtures of cyclohexane, decane, hexadecane, and squalane with hexane at 298.15 K and atmospheric pressure. From these measurements the excess molar volumes, V_m^E, viscosity deviations, δη, and the change in refractive indices on mixing, Δn_D, were calculated. These results were fitted to Redlick–Kister polynomial equations to estimate the binary coefficients and standard errors. The effects of size and shape of the components on excess properties have been discussed.     

Thermal conductivity of gaseous fluorocarbon refrigerants R 12, R 13, R 22, and R 23, under pressure

The thermal conductivity of four gaseous fluorocarbon refrigerants has been measured by a vertical coaxial cylinder apparatus on a relative basis. The fluorocarbon refrigerants used and the ranges of temperature and pressure covered are as follows: R 12 (Dichlorodifluoromethane CCl₂F₂): 298.15–393.15 K, 0.1–4.28 MPa R 13 (Chlorotrifluoromethane CClF₃): 283.15–373.15 K, 0.1–6.96 MPa R 22 (Chlorodifluoromethane CHClF₂): 298.15–393.15 K, 0.1–5.76 MPa R 23 (Trifluoromethane CHF₃): 283.15–373.15 K, 0.1–6.96 MPaThe apparatus was calibrated using Ar, N₂, and CO₂ as the standard gases. The uncertainty of the experimental data is estimated to be within 2%, except in the critical region. The behavior of the thermal conductivity for these fluorocarbons is quite similar; thermal conductivity increases with increasing pressure. The temperature coefficient of thermal conductivity at constant pressure, (/T) _p , is positive at low pressures and becomes negative at high pressures. Therefore, the thermal conductivity isotherms of each refrigerant intersect each other in a specific range of pressure. A steep enhancement of thermal conductivity is observed near the critical point. The experimental results are statistically analyzed and the thermal conductivities are expressed as functions of temperature and pressure and of temperature and density.     

A piezoelectric sensor for pressure measurements behind a shock front

The construction and measuring circuit of a pressure pickup designed for measurements in ionized gases behind a shock front are described. Calibration results are given, along with oscillograms of the pressure up to the arrival of the rarefaction wave.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 21, No. 1, pp. 168–171, July, 1971.     

Vapor+Liquid Equilibrium Measurements and Correlation of the Binary Refrigerant Mixtures Difluoromethane (HFC-32)+1,1,1,2,3,3-Hexafluoropropane (HFC-236ea) and Pentafluoroethane (HFC-125)+1,1,1,2,3,3-Hexafluoropropane (HFC-236ea) at 288.6, 303.2, and 318.2 K

Isothermal vapor–liquid equilibria (VLE) for the binary systems of difluoromethane (HFC-32)+1,1,1,2,3,3-hexafluoropropane (HFC-236ea) and pentafluoroethane (HFC-125)+1,1,1,2,3,3-hexafluoropropane (HFC-236ea) were measured at 288.6, 303.2, and 318.2 K using an apparatus in which the vapor phase was recirculated through the liquid. The phase composition at equilibrium was measured by gas chromatography, based on calibration using gravimetrically prepared mixtures. Both systems show a slight deviation from Raoult's law. The uncertainties in pressure, temperature, and vapor- and liquid-phase composition measurements were estimated to be no more than ±1 kPa, ±0.02 K, and ±0.002 mol fraction, respectively. The data were analyzed using the Carnahan–Starling–DeSantis equation of state.     

PVT measurements of liquid ethanol in the temperature range from 310 to 363 k at pressures up to 200 MPa

Density measurements in the compressed liquid phase for ethanol were performed with a metal-bellows variable volumometer for temperatures between 310 and 363 K at pressures from the vapor pressure to 200 MPa. The results cover the high-density region from 737 to 882 kg m_–3. The experimental uncertainties (total errors) of temperature, pressure, and density were estimated to be no greater than 3 mK, 0.1 %, and 0.1 %, respectively. Measurements of saturated liquid density at temperatures of 310, 340, and 360 K are also reported.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

Critical discharge of saturated and subcooled water through channels of different shapes

A complex experimental investigation of the outflow of saturated and subcooled water through channels of different forms has been carried out in the pressure range of 5–20 bar; the investigation included the measurements of the discharge, static pressure curves, moisture content field of the two-phase flow, and the photographic recording of the evaporation process. Empirical equations are proposed for determining the critical discharge.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 32, No. 6, pp. 990–994, June, 1977.     

Low-temperature compressibilities and absolute de Haas-van Alphen frequencies in potassium,rubidium, and cesium

The absolute de Haas-van Alphen (dH-vA) frequencies and the scaling effect of small hydrostatic pressures on extremal cross sections of the Fermi surface have been measured in freely mounted samples of K, Rb, and Cs. The dH-vA frequencies are in good agreement with those derived from currently accepted values for the low-temperature lattice constants of the three metals at (1.824±0.002), (1.603±0.003), and (1.365±0.002)×10⁸ G, respectively. The low-temperature compressibilities derived from the pressure measurements at (2.57₇±0.013), (3.64₄±0.015), and (4.02₀±0.02)×10^–2 kbar^–1, respectively, show discrepancies of –5, –8, and –14% with those measured by more conventional techniques. The characteristic energyB ₀ V ₀ (bulk modulus × atomic volume) is found to be constant at about 1.67×10⁵ J/mole in the three metals.