J. S. Gallagher

Refractive index of water and steam as function of wavelength, temperature and density

Based on a comprehensive collection of data previously obtained by Thormahlen et al. on the experimental refractive index of water and steam from the 1870s to the present, a new formulation is presented for the range of 0.2 to 2.5 μm in wave‐length, −10 to +500 °C in temperature and 0 to 1045 kg m−3 in density. The Lorentz‐Lorentz function or molar refraction, a strong function of wavelength but only weakly dependent on density and temperature, is fitted to a selected set of accurate refractive index data. The NBS/NRC equation of state for water and steam, the new international standard, is used to convert the experimental pressures to density.The deviations of all experimental data from the formulation are shown. A detailed assessment of the accuracy of the formulation is presented. Although the formulation does not represent to within their accuracy the data from the best sets in the visible range for liquid water below the boiling point, we show that inconsistencies between data sets, and minor deficie...

Revised Formulation for the Refractive Index of Water and Steam as a Function of Wavelength, Temperature, and Density

Schiebener et al. published a formulation for the refractive index of water and steam in 1990 [J. Phys. Chem. Ref. Data 19, 677 (1990)]. It covered the ranges 0.2 to 2.5 μm in wavelength, −12 to 500 °C in temperature, and 0 to 1045 kg m−3 in density. The formulation was adopted by the International Association for the Properties of Water and Steam (IAPWS) in 1991. In the present article, the data, after conversion to ITS-90, have been refitted to the same functional form, but based on an improved equation of state for water adopted by IAPWS in 1995. The revised coefficients are reported, and some tabular material is provided. The revised refractive-index formulation was adopted by IAPWS in 1997 and is available as part of a National Institute of Standards and Technology Standard Reference Database. For most conditions, the revised formulation does not differ significantly from the previous one. A substantial improvement has been obtained in supercooled water at ambient pressure, where the previous formula...

Thermodynamic Properties of Ammonia

An analytic thermodynamic surface has been fitted to the experimental data for ammonia for the temperature range extending from the triple point to 750 kelvins and for the pressure range extending from the dilute gas to 500 MPa (5000 bar). Values for the thermodynamic properties are tabulated at closely spaced intervals. A major part of the correlation was devoted to a study of the extent to which thermodynamic inconsistencies degrade the accuracy of the derived properties. This study focused as much on methods for correlating the data as on the data themselves. As a consequence, we are able to assign close tolerances to the tabulated thermodynamic properties over the range of the surface, including properties for the coexisting phases and even close to the liquid‐vapor critical point.

The Thermodynamic Behavior of the CO2‐H2O System from 400 to 1000 K, up to 100 Mpa and 30% Mole Fraction of CO2

A model is presented for the thermodynamic properties of the aqueous mixture of carbon dioxide, up to 30 mol% composition, in a large range of temperatures (400–1000 K) and pressures (0–100 MPa) around the critical point of water. The model for the Helmholtz free energy of the mixture is based on the principle of generalized corresponding states, with the NBS/NRC Steam Tables as the reference state for pure water. Input to the model are data for the critical line of the mixture, apparent molar volume and pVTx data in supercritical water, phase boundaries, excess enthalpies and mixture second virial coefficient data. Comparisons are presented with those data, with Henry’s constants and with other formulations available for this system. Phase boundaries and tabulated values of molar volumes, enthalpies, and fugacities are presented along 35 isobars from 0.05 to 100 MPa, for four compositions, x=0.05, 0.10, 0.20, and 0.30, respectively, at 19 temperatures in the range of 400 to 1000 K. For the same pressures...

Critical Analysis of Heat—Capacity Data and Evaluation of Thermodynamic Properties of Ruthenium, Rhodium, Palladium, Iridium, and Platinum from 0 to 300K. A Survey of the Literature Data on Osmium.

The literature sources of heat‐capacity data on ruthenium, rhodium, palladium, osmium, iridium, and platinum have been compiled and the data critically analyzed. Except for osmium where data are lacking, best values of thermodynamic properties have been evaluated between 0 and 300 K from the analyses. The literature values of heat capacity, the electronic coefficient of heat capacity (γ), and the zero K limiting Debye characteristic temperature (θD(0)) are compared. The sources of data are tabulated chronologically along with the temperature range of measurements, purity of sample, and the pertinent experimental procedures used. A bibliography of the references is listed.

The search for tricriticality in binary mixtures of near-critical propane and normal paraffins

Abstract This paper reports on three-phase equilibria liquid + liquid + vapor of binary mixtures of near-critical propane and higher normal paraffins. Special attention has been given to locate the (pseudo-)binary first showing partial miscibility in the liquid phase. For that purpose the three-phase equilibria liquid + liquid + vapor, including critical endpoints, have been determined experimentally in the binaries C 3 + C 32 , C 3 + C 34 , C 3 + C 36 , C 3 + C 38 , C 3 + C 40 C 3 + C 44 , C 3 + C 46 and C 3 + C 50 . Extrapolation of the results obtained shows that for a carbon number between 29 and 30 tricriticality has to be expected. In order to model the measured three-phase equilibrium data, an algorithm has been developed on the basis of the simplified perturbed hard chain theory. The calculations are still in progress.

Sixteen Thousand Evaluated Experimental Thermodynamic Property Data for Water and Steam

As part of the activities of the International Association for the Properties of Water and Steam, all reliable sources of experimental data on the thermodynamic properties of ordinary (light) water and steam have been collected and converted to common temperature, pressure, volume, mass and heat scales. The data are grouped by state or phase: ideal‐gas properties; sublimation and melting curves; saturation properties; properties of liquid water at ambient pressure; thermodynamic properties of the single‐phase state; and those of metastable states. In each category, a subdivision is made by property. Properties include the volume, enthalpy, heat capacities, sound velocity, internal energy and Joule‐Thomson and related coefficients. The total data collection contains approximately 16 000 data points and covers a century of experimental work at temperatures from 253 to 1273 K and pressures up to 1 GPa. This report characterizes the data and gives the literature references. The actual data collection is avail...

Standard states, reference states and finite-concentration effects in near-critical mixtures with applications to aqueous solutions

Abstract The excess Gibbs free energy reference states of both solvent and solute, as commonly used for aqueous solutions, behave anomalously near the critical point of water. This leads to a concentration-dependence of the partial and apparent molar properties that is stronger than usually assumed for nonelectrolyte as well as for electrolyte solutions, and affects a large range of pressure-temperature space where water is highly compressible. As a consequence, extrapolation techniques developed for extracting infinite-dilution properties from data at finite concentration will fail. Examples from various experimental sources, including recent volume measurements in supercritical dilute aqueous CO 2 , will be used to make this point. The anomalous initial concentration dependence of apparent molar properties interferes with the determination of the Debye-Huckel slopes as currently practiced. Even more seriously, the Debye-Huckel limiting law description, conventionally incorporated in the excess Gibbs free energy, fails when the compressibility of the solvent changes rapidly. A more appropriate frame of reference will be proposed.

Modeling the thermodynamic properties of sodium chloride in steam through extended corresponding states

Recent precise data on anomalous behavior of apparent molar properties of electrolyte solutions in near-critical steam have raised important questions as to how the thermodynamic properties of these systems should be described. Current Gibbs free energy models fail for highly compressible solutions. Here, a Helmholtz free energy formulation is presented as a first step in modeling compressible dilute aqueous electrolyte solutions. Comparisons are made with the known critical line, coexistence curves, apparent molar volumes, and heat capacities of NaCl in steam, and conclusions presented on improving the model.

Supplementary Backward Equations T(p,h), v(p,h), and T(p,s), v(p,s) for the Critical and Supercritical Regions (Region 3) of the Industrial Formulation IAPWS-IF97 for Water and Steam

In modeling advanced steam power cycles, thermodynamic properties as functions of pressure and enthalpy (p,h) or pressure and entropy (p, s) are required in the critical and supercritical regions (region 3 of IAPWS-IF97). With IAPWS-IF97, these calculations require cumbersome two-dimensional iteration of temperature T and specific volume v from (p,h) or (p,s). While these calculations in region 3 are not frequently required, the computing time can be significant. Therefore, the International Association for the Properties of Water and Steam (IAPWS) adopted backward equations for T(p,h), v(p,h), T(p ,s), and v(p,s) in region 3, along with boundary equations for the saturation pressure as a function of enthalpy, P 3sat (h), and of entropy, p 3Sat (s). Using the new equations, two-dimensional iteration can be avoided. The numerical consistency of temperature and specific volume obtained in this way is sufficient for most uses. This paper summarizes the need and the requirements for these equations and gives complete numerical information. In addition, numerical consistency and computational speed are discussed.