M. Uematsu

Static Dielectric Constant of Water and Steam

This paper reviews and evaluates the experimental works of the static dielectric constant (permittivity) of water and steam over the century. The critically evaluated experimental data are represented by a function of temperature and density. This representation was carefully examined in the light of the criteria for smoothness and physical plausibility. As a result of this work, which was largely stimulated by the activities of the International Association for the Properties of Steam, a new International formulation for the static dielectric constant of water and steam was adopted. This formulation covers a temperature range from 0 to 550 °C and a pressure range up to 500 MPa.

New International Skeleton Tables for the Thermodynamic Properties of Ordinary Water Substance

The current knowledge of thermodynamic properties of ordinary water substance is summarized in a condensed form of a set of skeleton steam tables, where the most probable values with the reliabilities on specific volume and enthalpy are provided in the range of temperatures from 273 to 1073 K and pressures from 101.325 kPa to 1 GPa and at the saturation state from the triple point to the critical point. These tables have been accepted as the IAPS Skeleton Tables 1985 for the Thermodynamic Properties of Ordinary Water Substance(IST‐85) by the International Association for the Properties of Steam(IAPS). The former International Skeleton Steam Tables, October 1963(IST‐63), have been withdrawn by IAPS. About 17 000 experimental thermodynamic data were assessed and classified previously by Working Group 1 of IAPS. About 10 000 experimental data were collected and evaluated in detail and especially about 7000 specific‐volume data among them were critically analyzed with respect to their errors using the statistical method originally developed at Keio University by the first three authors. As a result, specific‐volume and enthalpy values with associated reliabilities were determined at 1455 grid points of 24 isotherms and 61 isobars in the single‐fluid phase state and at 54 temperatures along the saturation curve. The background, analytical procedure, and reliability of IST‐85 as well as the assessment of the existing experimental data and equations of state are also discussed in this paper.

Measurements of the vapor-liquid coexistence curve and the critical parameters for 1,1,1,2-tetrafluoroethane

Measurements of the vapor-liquid coexistence curve in the critical region for 1,1,1,2-tetrafluoroethane (R134a; CH2FCF3), which is currently considered as a prospective substitute for conventional refrigerant R12, have been performed by visual observation of the disappearance of the meniscus at the vapor-liquid interface within an optical cell. Twenty-seven saturated densities along the vapor-liquid coexistence curve between 208 and 999 kg·m−3 have been obtained in the temperature range 343 K to the critical temperature. The experimental uncertainties in temperature and density measurements have been estimated to be within ±10mK and ±0.55%, respectively. On the basis of these measurements near the critical point, the critical temperature and the critical density for 1,1,1,2-tetrafluoroethane were determined in consideration of the meniscus disappearing level as well as the intensity of the critical opalescence. In addition, the critical exponent ß along the vapor-liquid coexistence curve has been determined in accord with the difference between the density of the saturated liquid and that of the saturated vapor.

Thermodynamic properties of 1,1-difluoroethane in the super-critical and high-density regions

The volumetric properties of 99.9% pure 1,1-difluoroethane were measured in the range of temperatures from 320 to 400 K by a variable volume method using a metal bellows. The unsmoothed 221 PVT measurements along 14 isotherms, which cover the region of densities between 232 and 883 kg/m3 up to a maximum pressure of 10.0 MPa, are reported. The uncertainties in the temperature, pressure, and density measurements were estimated to be 6 mK, 2.1kPa, and 0.3%, respectively. Based in these results, the derivatives were calculated and the behavior of the isothermal compressibility and volume expansion coefficient in the high-density region is shown as a function of temperature and pressure. Thevapor pressures were also measured at seven different temperatures of 320, 350, 353.16, 360, 380, 384.95, and 385 K, and the results are compared with the data in the literature. Saturated vapor and liquid densities were measured to confirm the reliability of the present results.

Orthobaric liquid densities of trichlorofluoromethane, dichlorodifluoromethane, chlorodifluoromethane, 1,1,2-trichlorotrifluoroethane, 1,2-dichlorotetrafluoroethane, and of the azeotropic mixture of (chlorodifluoromethane + chloropentafluoroethane) between 203 and 463 K

Abstract The orthobaric liquid densities of six halogenated hydrocarbons: trichlorofluoromethane (CCl 3 F), dichlorodifluoromethane (CCl 2 F 2 ), chlorodifluoromethane (CHClF 2 ), 1,1,2-trichlorotrifluoroethane (CCl 2 FCClF 2 ), 1,2-dichlorotetrafluoroethane (CClF 2 CClF 2 ), and of (0.6321CHClF 2 + 0.3679CClF 2 CF 3 ), an azeotropic mixture, have been measured. Measurements were carried out with a magnetic densimeter for temperatures from 203 K up to a temperature close to the critical. An accuracy of ±0.1 per cent except for the results at temperatures above 423 K was confirmed by examining the present measurements for orthobaric (liquid + gaseous) water. The temperature dependence of the orthobaric liquid density has been correlated analytically on the basis of the present results and the more reliable of the reported measurements critically evaluated by the present authors.

Densities of 2,2,2-trifluoroethanol in the temperature range from 310 K to 420 K II. Compressed-liquid densities at pressures up to 200 MPa

Density measurements at given temperatures and pressures in the compressed liquid phase for 2,2,2-trifluoroethanol were carried out with a metal-bellows variable volumometer. The results cover the high-density region from 1111 kg·m−3 to 1553 kg·m−3 along 15 isotherms between 310 K and 420 K at pressures from 0.1 MPa to 200 MPa. The experimental uncertainties of temperature T, pressure p, and density ρ, were estimated to be ≯ |3 mK|, |0.0010·p|, and |0.0010·ρ|, respectively. On the basis of the present results, the isothermal compressibility and the isobaric expansivity were calculated.

Saturated liquid density of 1,1difluoroethane(R 152a) and thermodynamic properties along the vaporliquid coexistence curve

Abstract Saturated liquid densities of 1,1-difluoroethane(CH 3 CHF 2 ) are measured at temperatures from 223 K to 363 K with the estimated uncertainty of 0.2 % by magnetic densimetry. The experimental results are compared with the available experimental data and some correlations and equations of state. A simple correlation for the saturated liquid density is developed as a function of temperature. This correlation covers the temperature range up to the critical point which reproduces the present experimental results with the percent mean deviation of 0.11 %. Adding the available experimental data with respect to the vapor pressure, critical parameters, saturated vapor density, and the second virial coefficient to the present saturated liquid density data, the parameters of the Redlich-Kwong-Soave equation of state are determined and the thermodynamic properties along the vaporliquid coexistence curve are derived.

Procedures for determining the critical parameters of fluids

An apparatus and procedures to determine the critical parameters and the vapor–liquid coexistence curve in the critical region by observing the disappearance of the vapor–liquid interface are described. The apparatus has the advantage of measuring the saturated vapor and liquid densities with only a single filling of the sample, and the procedures are applicable not only to pure fluids but also to mixtures. Three densities of liquid and eight of vapor on the coexistence curve for trifluoromethane are obtained, and the critical temperature, density, and pressure are also determined.

Monte Carlo simulation of negative ion production in the negative hydrogen ion source

Two Monte Carlo simulation codes: (a) neutral transport code and (b) negative ion (H−) transport code, have been developed to understand transport phenomena in negative ion sources. In the neutral transport code, Boltzmann equations for hydrogen molecules (H2) and atoms (H) are solved. Three dimensional (3D) spatial distributions of H2, H, and H− production are obtained for a tandem negative ion source. The volume production of H− is limited to the area around the gas inlet in the first chamber and near the plasma grid in the second chamber. On the other hand, distribution of H− surface production is shown to be almost uniform over all the plasma grid surface. In the negative ion code, H− trajectories are calculated by numerically solving the 3D equation of motion for H− ions. The effects of the magnetic filter on the extraction probability of surface produced H− ions are mainly studied. The dependence of the extraction probability on the field strength is small.

Apparatus for measurements of PVT properties and their derivatives for fluids and fluid mixtures with a metal bellows as a variable‐volume vessel

A new apparatus for measurements of PVT properties and their derivatives with a metal bellows was designed for fluids and fluid mixtures of a fixed composition for pressures up to 20 MPa in the range of temperatures from room‐temperature condition to 473 K. The apparatus, procedures, and results of calibrations are described. The capabilities of the apparatus are illustrated by means of the vapor‐pressure measurements for chlorodifluoromethane and the PVT measurements of sulfur hexafluoride. Temperatures were set and kept constant at the values desired within ±3 mK and pressures within ±2 kPa. It was shown that density derivatives with respect to pressure at constant temperature and those with respect to temperature at constant pressure may both obtain from the experimental results.