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  • Artikel: DFG Deutsche Nationallizenzen  (6)
  • 1995-1999  (6)
  • 1935-1939
  • alternative refrigerants  (4)
  • equation of state  (2)
Datenquelle
  • Artikel: DFG Deutsche Nationallizenzen  (6)
Materialart
Erscheinungszeitraum
Jahr
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 17 (1996), S. 1269-1280 
    ISSN: 1572-9567
    Schlagwort(e): alternative refrigerants ; collision integrals ; second virial coefficient ; spherically averaged potential ; viscosite
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The second virial coefficients of refrigerants HFC-32 (CH2F2), HFC-23 (CHF3), and HCFC-22 (CHC1F2) have been correlated on the bisis of site site model potential and have been compared with experimental results. The molecular interactions consisted of repulsion dispersion and electrostatic parts. From the site site potentials adjusted to the experimental second virial coefficients, spherically averaged potentials have been determined and a subsequent calculation of gaseous viscosity has been carried out. Agreement between measured and calculated values of second virial coellicients and gaseous viscosity is satisfactory. Calculated values of second virial coefficients and gaseous viscosity beyond available experimental data, therefore. can be assumed as a reliable extrapolation to lower and higher temperatures.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 20 (1999), S. 1639-1651 
    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
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    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
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 20 (1999), S. 97-106 
    ISSN: 1572-9567
    Schlagwort(e): alternative refrigerants ; binary refrigerant mixtures ; dew point pressures ; HFC-125+HFC-143a system ; PVTx properties ; saturated vapor densities ; virial coefficients
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The experimental PVTx properties of a binary refrigerant mixture, R-125 (pentafluoroethane)+R-143a (1,1,1-trifluoroethane), have been measured for a composition of 50 mass% R-125 by a constant-mass method coupled with an expansion procedure in a range of temperatures from 305 to 400 K, pressures from 1.5 to 6.1 MPa, and densities from 92 to 300 kg·m−3. The experimental uncertainties of the present measurements are estimated to be within ±7.2 mK in temperature, ±3.0 kPa in pressure, ±0.12 kg·m−3 in density, and ±0.040 mass% in composition. The sample purities are 99.953 mass% for R-125 and 99.998% for R-143a. Seven saturated vapor densities and dew point pressures of the R-125+R-143a system were determined, on the basis of rather detailed PVTx properties measured in the vicinity of the saturation boundary as well as the thermodynamic behavior of isochores near saturation. The second and third virial coefficients for temperatures from 330 to 400 K were also determined.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 20 (1999), S. 923-932 
    ISSN: 1572-9567
    Schlagwort(e): alternative refrigerants ; critical density ; critical locus ; critical temperature ; R-32/125 mixture ; R-125/143a mixture ; saturation density
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract R-32/125 (difluoromethane/pentafluoroethane) and R-125/143a (pentafluoro-ethane/l,l,l-trifluoroethane) binary systems are promising alternative refrigerants to replace conventional refrigerants, i.e., R-22 and R-502. The saturated vapor- and liquid-density data in the critical region of these mixtures were measured using the visual observation of the meniscus disappearance in an optical cell. For the R-32/125 system, 35 saturation density data were measured at three compositions, 10, 35, and 50 mass% R-32. Nineteen saturation density data were also measured for R-125/143a (50/50 mass%). The critical temperatures and densities for these binary refrigerants were determined by taking into consideration the level and location of the meniscus disappearance as well as the intensity of the critical opalescence. Correlations to represent the critical loci of these binary refrigerants for an entire range of compositions have been developed. The experimental uncertainties of the saturation density data are estimated to be within 9 mK in temperature and 0.5 to 5.0 kg · m−3 in density. The uncertainties of the critical temperature and density are estimated to be within 12 to 14mK and 4 to 8kg · m–3, respectively.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    International journal of thermophysics 16 (1995), S. 801-810 
    ISSN: 1572-9567
    Schlagwort(e): alternative refrigerants ; binary mixtures ; bubble-point pressure ; saturated-liquid density ; vapor-liquid equilibria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Bubble-point pressures and saturated-liquid densities of the binary R-135 (pentafuoroethane) + 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. and density measurements and the composition determination were estimated to be within ±15 mK, ±13 k Pa, ±0.2%, and ±0.1 wt%, respectively. The purities of the samples used throughout the measurements are 99.98 wt% for R-125 and 99.0 mol % for R- 143a. Based on the present data, the thermodynamic behavior of the vapor-liquid equilibria of this binary refrigerant mixture has been evaluated by using the Peng-Robinson equation for the bubble-point pressures, and the modified Hankinson-Brobst-Thomson equation for the saturated-liquid densities. This was done to identify the optimized binary interaction parameters.
    Materialart: Digitale Medien
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