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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 13 (1992), S. 931-942 
    ISSN: 1572-9567
    Keywords: capillary viscometer ; HFC 134a ; 1, 1, 1, 2-tetrafluoroethane ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity of HFC 134a was measured over the range of temperatures from 213 to 423 K and pressures up to 30 MPa. The experimental method was that of the capillary flow and a closed-circuit high-pressure viscometer was used. The sample fluid was circulated through a stainless-steel capillary from a highpressure plunger system. The constant of the capillary was calibrated against the reference standard, pure water. The viscosity of the sample was calculated from the flow rate, the pressure drop at the capillary, and the capillary constant using the Hagen-Poiseuille equation. Measurements were made at a total of 39 points on eight isotherms. The measurement uncertainty of the viscosities was estimated as ±1.3%. Based on the present results, an empirical equation for the viscosity of HFC 134a has been correlated. The viscosity on the saturation line calculated by the equation compares with experimental viscosity data in other previous studies. There are rather considerable differences among these measurements. Comparisons of the data for HFC 134a with those for CFC 12 show that the viscosity of HFC 134a is similar in magnitude to that of CFC 12 at temperatures around 300 K but is higher at lower temperatures and lower at higher temperatures. The pressure gradients for these two corresponding substances are similar over the entire temperature range.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 13 (1992), S. 401-410 
    ISSN: 1572-9567
    Keywords: capillary viscometer ; 1,1-dichloro-2,2,2-trifluoroethane ; HCFC 123 ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The viscosity of HCFC 123 was measured over the range of temperature from 223 to 418 K and pressure up to 20 MPa. The experimental method was that of the capillary flow and a closed-circuit high-pressure viscometer was used. The sample fluid was circulated through a Pyrex glass capillary from a high-pressure plunger system. The constant of the Pyrex glass capillary was calibrated against the reference standard, pure water. The viscosity of the sample was calculated from the flow rate, the pressure drop at the capillary, and the capillary constant using the Hagen-Poiseuille equation. Measurements were made on seven isotherms. In the case of the transpiration method, the density is needed for calculation of the viscosity from the kinematic viscosity. The available density data of HCFC 123 are less reliable than those for CFC 11. Therefore, uncertainty in the viscosity of HCFC 123 is larger, although the measured kinematic viscosity itself has a reproducibility of 0.1 %. HCFC 123 is proposed as an alternative to CFC 11. Comparisons of the data for these two substances show that the viscosity of HCFC 123 is similar in magnitude to that of CFC 11 at temperatures around 350 K, higher at lower temperatures, and lower at higher temperatures. The pressure gradients for these two corresponding substances are similar over the entire temperature range.
    Type of Medium: Electronic Resource
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