In a preceding project, functional forms for "short" Helmholtz energy equations of state for typical nonpolar and weakly polar fluids and for typical polar fluids were developed using simultaneous optimization. In this work, the coefficients of these short forms for the equations of state have been fitted for the fluids acetone, carbon monoxide, carbonyl sulfide, decane, hydrogen sulfide, 2-methylbutane (isopentane), 2,2-dimethylpropane (neopentane), 2-methylpentane (isohexane), krypton, nitrous oxide, nonane, sulfur dioxide, toluene, xenon, hexafluoroethane (R-116), 1,1-dichloro-1-fluoroethane (R-141b), 1-chloro-1,1-difluoroethane (R-142b), octafluoropropane (R-218), 1,1,1,3,3-pentafluoropropane (R-245fa), and fluoromethane (R-41). The 12 coefficients of the equations of state were fitted to substance specific data sets. The results show that simultaneously optimized functional forms can be applied to other fluids out of the same class of fluids for which they were optimized without significant loss of accuracy. The high numerical stability of the functional forms resulted in successful fits for fluids that previously could not be described by accurate empirical equations of state. For R-41, it is shown that the accuracies can be increased further by fitting the temperature exponents in addition to the coefficients of the equation of state, provided that highly accurate experimental data are available. Typical uncertainties of properties calculated using the new equations are 0.2 % in density, 1 % to 2 % in heat capacity and liquid-phase speed of sound, and 0.2 % in vapor pressure. Where data are available, uncertainties in vapor-phase sound speeds are generally less than 0.1 %.

A new formulation for the thermodynamic properties of nitrogen has been developed. Many new data sets have become available, including high accuracy data from single and dual-sinker apparatuses which improve the accuracy of the representation of the pT surface of gaseous, liquid, and supercritical nitrogen, including the saturation states. New measurements of the speed of sound from spherical resonators yield accurate information on caloric properties in gaseous and supercritical nitrogen. Isochoric heat capacity and enthalpy data have also been published. Sophisticated procedures for the optimization of the mathematical structure of equations of state and special functional forms for an improved representation of data in the critical region were used. Constraints regarding the structure of the equation ensure reasonable results up to extreme conditions of temperature and pressure. For calibration applications, the new reference equation is supplemented by a simple but also accurate formulation, valid only for supercritical nitrogen between 250 and 350 K at pressures up to 30 MPa. The uncertainty in density of the new reference equation of state ranges from 0.02% at pressures less than 30 MPa up to 0.6% at very high pressures, except in the range from 270 to 350 K at pressures less than 12 MPa where the uncertainty in density is 0.

An equation of state is presented for the thermodynamic properties of propane that is valid for temperatures from the triple point temperature (85.525 K) to 650 K and for pressures up to 1000 MPa. The formulation can be used for the calculation of all thermodynamic properties, including density, heat capacity, speed of sound, energy, and saturation properties. Comparisons to available experimental data are given that establish the accuracy of calculated properties. The approximate uncertainties of properties calculated with the new equation are 0.01 % to 0.03 % in density below 350 K, 0.5 % in heat capacities, 0.03 % in the speed of sound between (260 and 420) K, and 0.02 % in vapor pressure above 180 K. Deviations in the critical region are higher for all properties except vapor pressure.

If the potential for a boom in the global hydrogen economy is realized, there will be an increase in the need for accurate hydrogen thermodynamic property standards. Based on current and anticipated needs, new fundamental equations of state for parahydrogen, normal hydrogen, and orthohydrogen were developed to replace the existing property models. To accurately predict thermophysical properties near the critical region and in liquid states, the quantum law of corresponding states was applied to improve the normal hydrogen and orthohydrogen formulations in the absence of available experimental data. All three equations of state have the same maximum pressure of 2000MPa and upper temperature limit of 1000K. Uncertainty estimates in this paper can be considered to be estimates of a combined expanded uncertainty with a coverage factor of 2 for primary data sets. The uncertainty in density is 0.04% in the region between 250 and 450K and at pressures up to 300MPa. The uncertainties of vapor pressures and saturated liquid densities vary from 0.1% to 0.2%. Heat capacities are generally estimated to be accurate to within 1%, while speed-of-sound values are accurate to within 0.5% below 100MPa.

All reliable sources of data for the static dielectric constant or relative pennittivity of water and steam, many of them unpublished or inaccessible, have been collected, evaluated, corrected when required, and converted to the ITS-90 temperature scale. The data extend over a temperature range from 238 to 873 K and over a pressure range from 0.1 MPa up to 1189 MPa. The evaluative part of this work includes a review of the different types of measurement techniques, and the corrections for frequency dependence due to the impedance of circuit components, and to electrode polarization. It also includes a detailed assessment of the uncertainty of each particular data source, as compared to other sources in the same range of pressure and temperature. Both the raw and the corrected data have been tabulated, and are also available on diskette. A comprehensive list of references to the literature is included.