Density and thermal conductivity of R-409a refrigerant in the gaseous state


O. Verba1, S. Komarov1, E. Raschektaeva1 and S. Stankus1

1Kutateladze Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia

Keywords: gaseous state, experimental data
property: density, thermal conductivity
material: R-409a refrigeration

Freons R-409a have been considered as an alternative to R-12 in refrigeration and air conditioning applications. Reliable experimental data are needed for design of power equipment and for scientific research. We failed to find in the literature data on thermal conductivity and density of gaseous R-409a within a single-phase area. New experimental density (293-373 K, 0.3-2.5 MPa), thermal conductivity (306-425 K, 0.1-1.4 MPa) of the mixed refrigerant R-409A in the gaseous phase have been obtained in this work. The tables of the temperature and pressure dependences of these properties have been constructed. A cylindrical stainless steel isochoric piezometer was used for the measurement of the vapor density. The cell was immersed in a thermostatic bath. The temperature in the bath was held to within 10 mK throughout the measurements. The temperature of the piezometer was measured with a 10 ohm platinum resistance thermometer. The experimental uncertainty of the density measurements was estimated to be within 0.1-0.3 %. The thermal conductivity of the refrigerant in the vapor phase was measured by the steady-state coaxial cylinders method with error of 1.5-2.5 %. The length and diameters of outer nickel cylinder are 140 mm, 50/20 mm, respectively. An average (by the length and diameter) gap between the cylinders is equal to 0.366 mm. Experimental data for the density of superheated vapor were fitted by an eight-parameter equation of state of Benedict-Webb-Rubin. The standard deviation of the experimental points does not exceed 0.1 %. The thermal conductivity of R-409A in the vapor phase was measured along isotherms from 306 to 425 K at pressures from 0.1 to 1.4 MPa. The experimental data were fitted by empirical dependence on temperature and pressure. The standard deviation of the experimental points from calculated values does not exceed 0.45 %. Ideal-gas thermal conductivity and thermal conductivity on dew line were calculated based on obtained experimental data. We gratefully acknowledge the financial support for this research from the Russian Foundation for Basic Research.


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