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  • alternative refrigerant  (5)
  • virial coefficient  (3)
  • 1
    Digitale Medien
    Digitale Medien
    An experimental study of the thermodynamic properties of 1,1-difluoroethane (1992)
    Springer
    International journal of thermophysics 13 (1992), S. 985-997 
    Details
    ISSN: 1572-9567
    Schlagwort(e): critical parameters ; equation-of-state data ; HFC-152a ; vaporliquid equilibrium ; vapor pressure ; virial coefficient
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Experimental vapor pressures andP-ρ-T data of an important alternative refrigerant, 1, 1-difluoroethane (HFC-152a), have been measured by means of a constant-volume method coupled with expansion procedures. SixtyP-ρ-T data were measured along eight isochores in a range of temperaturesT from 330 to 440 K, at pressuresP from 1.6 to 9.3 MPa, and at densitiesρ from 51 to 811 kg·m−3. Forty-six vapor pressures were also measured at temperatures from 320 K to the critical temperature. The uncertainties of the temperature and pressure measurements are within ±7mK and ±2kPa, respectively, while the uncertainty of the density values is within ±0.1%. The purity of the sample used is 99.9 wt%. On the basis of the measurements along each isochore, five saturation points were determined and the critical pressure was determined by correlating the vapor-pressure measurements. The second and third virial coefficients for temperatures from 360 to 440 K have also been determined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01141210
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  • 2
    Digitale Medien
    Digitale Medien
    Ideal-gas specific heat and second virial coefficient of HFC-125 based on sound-velocity measurements (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 587-595 
    Details
    ISSN: 1572-9567
    Schlagwort(e): alternative refrigerant ; HFC-125 ideal-gas specific heat ; second acoustic-virial coefficient ; second virial coefficient ; sound velocity ; spherical resonator
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The sound velocity in gaseous pentafluoroethane (HFC-125, CF3CHF2) has been measured by means of a spherical acoustic resonator, Seventy-two sound-velocity values were measured with an uncertainty of ±0.01% at temperatures from 273 to 343 K and pressures from 101 to 250 kPa. The ideal-gas specific heats and the second acoustic-virial coefficients have been determined on the basis of the Sound-velocity measurements. The second virial coefficients calculated from the present sound-velocity measurements agree with literature values which were determined fromPVT measurements by means of a Burnett method.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01441505
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  • 3
    Digitale Medien
    Digitale Medien
    Measurements ofPVTx properties of refrigerant mixture HFC-32+HFC-125 in the gaseous phase (1996)
    Springer
    International journal of thermophysics 17 (1996), S. 43-54 
    Details
    ISSN: 1572-9567
    Schlagwort(e): alternative refrigerant ; binary refrigerant mixtures ; HFC-32+HFC-125 system ; PVTx properties ; thermodynamic properties ; virial coefficients
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The experimental 156PVTx properties of an important binary refrigerant mixture, HFC-32 (difluoromethane)+HFC-125 (pentafluorethane), have been measured for three compositions, i.e., 50, 60, and 80 wt% HFC-32, by a constant-mass-method coupled with expansion procedure in an extensive range of temperaturesT from 320 to 440 K, of pressuresP from 1.8 to 5.3 M Pa, and of densities p from 50 to 124 kg · m−3. The experimental uncertainties of the present measurements are estimated to be within ±7 mK in temperature, ±2 kPa in pressure, ±0.2% in density and ±0.02 wt% of HFC-32. The sample purities are 99.998 wt% for HFC-32 and 99.99 wt% for HFC-125. Seventy-eight second and third virial coeflicients for temperatures from 320 to 440 K have been determined by the present measurements.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01448208
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  • 4
    Digitale Medien
    Digitale Medien
    An Equation of State for 1,1,1-Trifluoroethane (R-143a) (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 1639-1651 
    Details
    ISSN: 1572-9567
    Schlagwort(e): alternative refrigerant ; equation of state ; Helmholtz energy ; R-143a ; 1,1,1-trifluoroethane
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract A fundamental equation of state has been developed for 1,1,1-trifluoroethane (R-143a) using the dimensionless Helmholtz energy. The experimental thermodynamic property data, which cover temperatures from the triple point (161 K) to 433 K and pressures up to 35 MPa, are used to develop the present equation. These data are represented by the present equation within their reported experimental uncertainties: ±0.1% in density for both vapor and liquid phase P–ρ–T data, ±1% in isochoric specific heat capacities, and ±0.02% in the vapor phase speed-of-sound data. The extended range of validity of the present model covers temperatures from 160 to 650 K and pressures up to 50 MPa as verified by the thermodynamic behavior of the isobaric heat-capacity values over the entire fluid phase.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1022645626800
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  • 5
    Digitale Medien
    Digitale Medien
    Determination of Second Virial Coefficients and Virial Equations of R-32 (Difluoromethane) and R-125 (Pentafluoroethane) Based on Speed-of-Sound Measurements (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 1677-1688 
    Details
    ISSN: 1572-9567
    Schlagwort(e): alternative refrigerant ; equation of state ; hydrofluorocarbon ; R-32 ; R-125 ; second virial coefficient ; speed of sound
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The second virial coefficients, B, for difluoromethane (R-32, CH2F2) and pentafluoroethane (R-125, CF3CHF2) are derived from speed-of-sound data measured at temperatures from 273 to 343 K with an experimental uncertainty of ±0.0072%. Equations for the second virial coefficients were established, which are valid in the extensive temperature ranges from 200 to 400 K and from 240 to 440 K for R-32 and R-125, respectively. The equations were compared with theoretically derived second virial coefficient values by Yokozeki. A truncated virial equation of state was developed using the determined equation for the virial coefficients. The virial equation of state represents our speed-of-sound data and most of the vapor PρT data measured by deVries and Tillner-Roth within ±0.01 and ±0.1%, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1022601811779
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  • 6
    Digitale Medien
    Digitale Medien
    Heat Capacities and Joule–Thomson Coefficients of HFC Refrigerants (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 141-148 
    Details
    ISSN: 1572-9567
    Schlagwort(e): ideal gas ; heat capacity ; hydrofluorocarbons ; Joule–Thomson coefficient ; R-32 ; R-125 ; R-134a ; R-143a ; R-152a ; virial coefficient
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract In this report, we have examined the behavior of heat capacities and Joule–Thomson coefficients in low- and moderate-density regions based on recent theoretical studies of the ideal-gas heat capacity and virial coefficients of R-32, R-125, R-134a, R-143a, and R-152a. The results have been compared with those derived from empirical equations of state which have been recently developed, based on a large quantity of experimental data for these refrigerants. Both results are in good agreement. Proper behaviors for these second-derivative properties justify the use of the empirical equations of state in low-temperature and low-density regions where no experimental data are available.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1021486432011
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  • 7
    Digitale Medien
    Digitale Medien
    Bubble-Point Pressures and Saturated- and Compressed-Liquid Densities of the Binary R-125 + R-143a System (1999)
    Springer
    International journal of thermophysics 20 (1999), S. 911-922 
    Details
    ISSN: 1572-9567
    Schlagwort(e): alternative refrigerant ; binary R-125 + R-143a mixtures ; bubble-point pressure ; compressed-liquid density ; R-125 ; R-143a ; saturated-liquid density ; vapor-liquid equilibria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Bubble-point pressures and saturated- and compressed-liquid densities of the binary R-125 (pentafluoroethane) + R-143a (1,1,1 -trifluoroethane) system have been measured for several compositions at temperatures from 280 to 330 K by means of a magnetic densimeter coupled with a variable-volume cell mounted with a metallic bellows. The experimental uncertainties of the temperature, pressure, density, and composition were estimated to be within ±10mK, ± 12 kPa, ±0.2%, and ±0.2mass%, respectively. The purities of the samples used throughout the measurements are 99.96 area% for R-125 and 99.94 area% for R-143a. Based on these measurements, the thermodynamic behavior of the vapor-liquid equilibria of this binary refrigerant mixture has been represented using the Peng–Robinson equation for the bubble-point pressures, a correlation for the saturated-liquid densities, and an equation of state for the compressed-liquid densities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1022643404972
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  • 8
    Digitale Medien
    Digitale Medien
    Ideal-Gas Heat Capacities and Virial Coefficients of HFC Refrigerants (1998)
    Springer
    International journal of thermophysics 19 (1998), S. 89-127 
    Details
    ISSN: 1572-9567
    Schlagwort(e): ideal gas ; heat capacity ; hydrofluorocarbons ; Stockmayer potential ; virial coefficient
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Thermodynamic properties of HFC (hydrofluorocarbon) compounds have been extensively studied with worldwide interest as alternative refrigerants. Both quality and quantity in the experimental data far exceed those for the CFC and HCFC refrigerants. These data now provide a great opportunity to examine the validity of theoretical models, and vice versa. Among them, the ideal-gas heat capacity C p 0 and virial coefficients derived from the experimental data are of particular interest, since they are directly related to the intramolecular and intermolecular potentials through the statistical mechanical procedure. There have been some discrepancies reported in the observed and theoretical C p 0 for HFC compounds. We have performed new calculations of C p 0 for several HFCs. The present results are consistent with the selected experimental values. The second (B) and third (C) virial coefficients have been reported for these HFC refrigerants from speed of sound data and Burnett PVT data. Often, a square well-type intermolecular potential is employed to correlate the data. However, the model potential cannot account consistently for both B and C coefficients with the same potential parameters. We have analyzed the data with the Stockmayer potential and obtained self-consistent results for various HFC (R-23, R-32, R-125, R-134a, R-143a, and R-152a) compounds with physically reasonable potential parameters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1021499018749
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