Volume 29, Issue 2, March 2000
Index of content:
Reference Data for the Thermal Conductivity of Saturated Liquid Toluene Over a Wide Range of Temperatures29(2000); http://dx.doi.org/10.1063/1.556057View Description Hide Description
Efficient design of industrial processes and equipment requires accurate thermal conductivity data for a variety of fluids, such as alternative refrigerants, fuels, petrochemicals, aqueous systems, molten salts, and molten metals. The accuracy of experimental thermal conductivity data is a function of the operating conditions of the instrument. Reference data are required over a wide range of conditions to verify the claimed uncertainties of absolute instruments and to calibrate relative instruments, since either type may be used to measure the thermal conductivity of fluids. Recently, accurate experimental data for the thermal conductivity of liquid toluene near the saturation line have been obtained, which allow the upper temperature limit of the previous reference-data correlation to be extended from 360 to 553 K. The thermal conductivity was measured using two transient hot-wire instruments from 300 to 550 K, the first with a bare 12.7 μm platinum wire and the second using an anodized 25 μm tantalum wire. Uncertainties due to the contribution of thermal radiation and the purity of the samples are discussed. The proposed value of the thermal conductivity of liquid toluene at 298.15 K and 0.1 MPa is The quality of the data is such that new improved recommendations and recommended values can be proposed with uncertainties at 95% confidence of 1% for 189 440 K, 1.5% for 440 480 K, and 2% for 480 553 K, near the saturation line.
29(2000); http://dx.doi.org/10.1063/1.556056View Description Hide Description
As part of a joint project between the International Association for the Properties of Water and Steam and the Subcommittee on Transport Properties of the International Union of Pure and Applied Chemistry Commission I.2 on Thermodynamics, all available and reliable experimental data on the viscosity and thermal conductivity of ordinary water and steam have been collected and converted to the current temperature scale (ITS-90) and a common set of units. The data are grouped according to state into four regions: the liquid phase (excluding data near 0.101 325 MPa), the steam (vapor) phase, the supercritical region for any pressure), and liquid water at ambient pressure (near 0.101 325 MPa) between the triple-point temperature and the normal boiling-point temperature. For each point with measuredtemperature and pressure (or at specified saturation conditions), a density has been computed with the current scientific standard thermodynamic formulation (IAPWS-95), and each experimental datum has been compared with the viscosity or thermal conductivity calculated from the current standard formulations for these properties. The total data collection contains 4090 points for viscosity in the range of temperatures from 238 to 1346 K with pressures to 346 MPa and 5107 points for thermal conductivity in the range of temperatures from 256 to 1191 K with pressures to 785 MPa. The current standard IAPWS formulations for the transport properties of water are based on correlations adopted in 1984 which considered experimental data available through 1980. The present study considers all data available in the earlier work, data collected in bibliographic efforts within IAPWS and documented in unpublished reports through 1988, and additional data published subsequent to the earlier reports or, in some cases, older data which were not considered in the previous compilations. Thus, this study has identified new data which were not available for the previous reviews of the transport properties of water, has identified regions in which the current standard transport property formulations can now be improved, and is intended to facilitate the development of new, more accurate, international formulations for the viscosity and thermal conductivity of water and steam.
Evaluated Kinetic and Photochemical Data for Atmospheric Chemistry: Supplement VIII, Halogen Species Evaluation for Atmospheric Chemistry29(2000); http://dx.doi.org/10.1063/1.556058View Description Hide Description
This paper updates and extends part of the previous data base of critical evaluations of the kinetics and photochemistry of gas-phase chemical reactions of neutral species involved in atmospheric chemistry [J. Phys. Chem. Ref. Data 9, 295 (1980); 11, 327 (1982); 13, 1259 (1984); 18, 881 (1989); 21, 1125 (1992); 26, 521 (1997); 26, 1329 (1997); 28, 191 (1999)]. The present evaluation is limited to the inorganic halogen family of atmospherically important reactions. The work has been carried out by the authors under the auspices of the IUPAC Subcommittee on Gas Phase Kinetic Data Evaluation for Atmospheric Chemistry. Data sheets have been prepared for 102 thermal and photochemical reactions, containing summaries of the available experimental data with notes giving details of the experimental procedures. For each thermal reaction, a preferred value of the rate coefficient at 298 K is given together with a temperature dependence where possible. The selection of the preferred value is discussed and estimates of the accuracies of the rate coefficients and temperature coefficients have been made for each reaction. For each photochemical reaction the data sheets list the preferred values of the photoabsorption cross sections and the quantum yields of the photochemical reactions together with comments on how they were selected. The data sheets are intended to provide the basic physical chemical data needed as input for calculations that model atmospheric chemistry. A table summarizing the preferred rate data is provided, together with an appendix listing the available values of enthalpies of formation of the reactant and product species.