A. R. H. Goodwin
National Institute of Standards and Technology
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Featured researches published by A. R. H. Goodwin.
Journal of Physical and Chemical Reference Data | 1995
D. P. Fernández; Y. Mulev; A. R. H. Goodwin; J. M. H. Levelt Sengers
All reliable sources of data for the static dielectric constant or relative permittivity of water and steam, many of them unpublished or inaccessible, have been collected, evaluated, corrected when required, and converted to the ITS‐90 temperature scale.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.
Review of Scientific Instruments | 1996
A. R. H. Goodwin; James B. Mehl; Michael R. Moldover
A reentrant rf cavity resonator has been developed for automated detection of phase separation of fluid mixtures contained within the cavity. Successful operation was demonstrated by redetermining the phase boundaries of a CO2+C2H6 mixture in the vicinity of its critical point. We developed an accurate electrical model for the resonator and used helium to determine the deformation of the resonator under pressure. With the model and pressure compensation, the resonator was capable of very accurate dielectric measurements. We confirmed this by remeasuring the molar dielectric polarizability Ae of argon and obtained the result Ae=(4.140±0.006) cm3/mol (standard uncertainty) in excellent agreement with published values. We exploited the capability for accurate dielectric measurements to determine the densities of the CO2+C2H6 mixture at the phase boundaries and to determine the dipole moment of 1,1,1,2,3,3‐hexafluoropropane, a candidate replacement refrigerant. Near the operating frequency of 375 MHz the capa...
International Journal of Thermophysics | 1992
A. R. H. Goodwin; Dana R. Defibaugh; Lloyd A. Weber
We measured the vapor pressure of chlorodifluoromethane (commonly known as R22) at temperatures between 217.1 and 248.5 K and of 1,1,1,2-tetrafluoroethane (commonly known as R134a) in the temperature range 214.4 to 264.7 K using a comparative ebulliometer. For 1,1,1,2-tetrafluoroethane at pressures between 220.8 and 1017.7kPa (corresponding to temperatures in the range 265.6 to 313.2K), additional measurements were made with a Burnett apparatus. We have combined our results for 1,1,1,2-tetrafluoroethane with those already published from this laboratory at higher pressures to obtain a smoothing equation for the vapor pressure from 215 K to the critical temperature. For chlorodifluoromethane our results have been combined with certain published results to provide an equation for the vapor pressure at temperatures from 217 K to the critical temperature.
Journal of Research of the National Institute of Standards and Technology | 1999
Michael R. Moldover; S J. Boyes; Christopher W. Meyer; A. R. H. Goodwin
We measured the acoustic resonance frequencies of an argon-filled spherical cavity and the microwave resonance frequencies of the same cavity when evacuated. The microwave data were used to deduce the thermal expansion of the cavity and the acoustic data were fitted to a temperature-pressure surface to deduce zero-pressure speed-of-sound ratios. The ratios determine (T–T90), the difference between the Kelvin thermodynamic temperature T and the temperature on the International Temperature Scale of 1990 (ITS-90). The acoustic data fall on six isotherms: 217.0950 K, 234.3156 K, 253.1500 K, 273.1600 K, 293.1300 K, and 302.9166 K and the standard uncertainties of (T−T90) average 0.6 mK, depending mostly upon the model fitted to the acoustic data. Without reference to ITS-90, the data redetermine the triple point of gallium Tg and the mercury point Tm with the results: Tg/Tw = (1.108 951 6 ± 0.000 002 6) and Tm/Tw= (0.857 785 5 ± 0.000 002 0), where Tw = 273.16 K exactly. (All uncertainties are expressed as standard uncertainties.) The resonator was the same one that had been used to redetermine both the universal gas constant R, and Tg. However, the present value of Tg is (4.3 ± 0.8) mK larger than that reported earlier. We suggest that the earlier redetermination of Tg was erroneous because a virtual leak within the resonator contaminated the argon used at Tg in that work. This suggestion is supported by new acoustic data taken when the resonator was filled with xenon. Fortunately, the virtual leak did not affect the redetermination of R. The present work results in many suggestions for improving primary acoustic thermometry to achieve sub-millikelvin uncertainties over a wide temperature range.
International Journal of Thermophysics | 1995
D. P. Fernández; A. R. H. Goodwin; J. M. H. Levelt Sengers
The static relative permittivity (dielectric constant) of water has been determined from capacitance measurements at frequencies between 0.1 and 10 kHz, in the temperature range from 273.2 to 373.2 K at ambient pressure. The capacitor used for these measurements was formed from sapphire-insulated concentric cylinders. The specific conductance of the water used was maintained within 20% of the lowest value ever observed, which is better than in all previous experiments in this range. The new data shed some light on a discrepancy between sets of literature data in liquid water between the triple and boiling points.
Review of Scientific Instruments | 1991
Keith A. Gillis; Michael R. Moldover; A. R. H. Goodwin
Accurate measurements of the speed of sound in gases are often made using metal resonators with small transducers that perturb the resonance frequencies in minor and predictable ways. We extend this method to gases that may be corrosive and to high temperatures by using remote transducers coupled to a resonator by acoustic waveguides. Thin metal diaphragms separate the waveguides from the resonator. Thus, only metal parts come into contact with the test gas. In the present apparatus, any gas compatible with gold and stainless steel can be studied.
Fluid Phase Equilibria | 1993
Dana R. Defibaugh; A. R. H. Goodwin; Graham Morrison; Lloyd A. Weber
Abstract Defibaugh D.R., Goodwin A.R.H., Morrison G. and Weber L.A., 1993. Thermodynamic properties of 1,1-dichloro-1-fluoroethane (R141b). Fluid Phase Equilibria 85: 271-284. Thermodynamic properties of 1,1-dichloro-1-fluoroethane (R141b) were measured using a vibrating-tube densimeter and two different ebulliometric techniques. The densimeter was used to measure compressed liquid densities, and the ebulliometers were used to study the vapor pressure. Measurements of the density were made between 278 and 369 K and between 100 and 6000 kPa. The vapor pressure was measured from 253 to 355 K at pressures from 10 to 449 kPa. Both the compressed liquid and the vapor pressure results are compared with other published data. Our results for the vapor pressure have been combined with results already published to obtain a correlation for the vapor pressure from 253 K to the critical point.
International Journal of Thermophysics | 1992
A. R. H. Goodwin; Dana R. Defibaugh; Graham Morrison; Lloyd A. Weber
The vapor pressure of 1, 1-dichloro-2, 2, 2-trifluoroethane (R123) has been measured at temperatures between 256.4 and 453.8 K by ebulliometric and static techniques. These results have been combined to obtain a correlation for the vapor pressure from 256.4 K to the critical temperature.
International Journal of Thermophysics | 1997
A. R. H. Goodwin; James B. Mehl
Equilibrium dipole moments of gaseous pentafluorodimethyl ether (HFE-125), 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), 1,1,1,2,3,3-hexafluoropropane (HFC-236ea) 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1,2,2,3-pentafluoropropane (HFC-245ca), 1,1,1,2,2-pentafluoropropane (HFC-245fa), and 1,1,1,2,2,3,3,4-octafluorobutane (HFC-338mccq) were obtained from the resonance frequency of a reentrant cavity at temperatures between 250 and 373K. The electronic contributions to the polarization were determined for each fluid from liquid-phase optical index of refraction measurements at 297 K.
Journal of Chemical & Engineering Data | 1993
Lloyd A. Weber; A. R. H. Goodwin