Robert D. Goodwin

Experimental melting and vapor pressures of methane

Thirteen melting pressures to 210 atm are represented by the Simon equation with a root mean square deviation of 0.05 atm (0.08 per cent). This representation is highly sensitive to the triple point temperature, yielding 90.680 K (IPTS-1968). These pressures agree within 0.5 per cent with the less precise data of one other investigator at temperatures above 93 K. One hundred and five vapor pressures from the triple point to the critical point are represented by a new, non-analytic equation with a root mean square relative deviation of 0.01 per cent. The derived triple point pressure is 0.1159 atm. At the assigned critical point temperature of 190.53 K the pressure is 45.356 atm. Deviations of some of the data from other sources exceed one per cent at T

Dielectric constant and polarizability of saturated and compressed fluid methane

Abstract Accurate measurements of the dielectric constant of methane have been made on the saturated liquid from near the triple point to 188 K and on the compressed fluid along selected isotherms from 100 K to 300 K and at pressures to 345 bar. The data are combined with accurate densities to obtain the molar polarizability and its dependence on density and temperature. The density range examined extends to nearly three times the critical density. The molar polarizability is found to increase initially with density and then decrease in qualitative agreement with theoretical predictions and the behaviour of other fluids.

SECOND AND THIRD VIRIAL COEFFICIENTS FOR HYDROGEN

Second and third virial coefficients for parahydrogen have been derived from closely spaced PVT data from 24 to 100 °K. They are in good agreement at 100 °K with published data for normal hydrogen. Analytical representations of the combined data from about 20 to 423 °K are presented which may be useful in computation of thermodynamic functions of the gas. These formulas are related to those resulting from the use of the Lennard-Jones potential.

The orthobaric densities of parahydrogen, derived heats of vaporization, and critical constants☆

Closely spaced experimental data are presented and used for defining a consistent set of values for critical constants that describe the two-phase boundaries between saturated liquid and saturated vapor. The heat of vaporization is derived. The various considerations affecting the selection of the critical temperatures are discussed. (C.E.S.)

The densities of saturated liquid hydrogen

Densities of para-hydrogen from l7 to 32 K are obtained by extrapolating newly determined compressed liquid isotherms to corresponding vapor pressures. Results are combined with earlier data for the range 14 to 20 f K and compared with normal hydrogen by means of densitytemperature relationships. (auth)

Pressure-density-temperature relations of freezing liquid parahydrogen to 350 atmospheres☆

Three new melting pressures for parahydrogen are utilized in an empirical, melting-line representation to obtain a provisional set of densities for liquid parahydrogen in equilibrium with solid parahydrogen. (C.E.S.)

Survey of current nbs work on properties of parahydrogen.

Subsequent to publication of the invaluable compilation of hydrogen properties by Woolley, Scott, and Brickwedde in 1948 [1], a greater-than-ever need developed for thermodynamic properties of parahydrogen at low temperatures and high pressures, where no data, existed. Many of the needed data have now been supplied by work at the CEL National Bureau of Standards. This report is designed to present a concise description of the various properties and to provide a bibliography of the original publications.

The Correlation of Experimental Pressure-Density-Temperature and Specific Heat Data for Parahydrogen

This chapter describes the correlation of experimental pressure-density-temperature and specific heat data for parahydrogen. Experimental programs have yielded values of pressure-density-temperature and of heat capacities at constant volume, in the temperature range from 14 to 100° K and at pressures from 2 to 350 atm. The two types of data have been correlated to yield a self-consistent set of thermodynamic functions. The smoothed isotherm polynomials permit calculation of pressures at even increments of density in gas and fluid phases. The pressure-temperature pairs so obtained for a given density, including the intersections at the appropriate lines of saturation, were fitted. A computer program has been developed which will find a value of density corresponding to an input temperature and pressure. The interpolation scheme utilizes the isotherm equations, the isochore equations, the virial expansion and the saturation boundaries. It is found that after the point on the P-Q-T surface is defined, the program calculates such properties as entropy, enthalpy and specific heat at constant volume.