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A Reference Quality Equation of State for Nitrogen



R Span, Eric Lemmon, R. T. Jacobsen, Wolfgang Wagner


A new formulation describing the thermodynamic properties of nitrogen has been developed. New data sets are now available which have been used to improve the representation of the 0-0-T surface of gaseous, liquid and supercritical nitrogen, including the saturated states. New measurements on the speed of sound from spherical resonators have used to improve the accuracy of caloric properties and special functional forms for an improved representation of data in the crical region were developed. The uncertainty of the new reference equation of state ranges from =or-}0.6% at very high pressures. The equation is valid from the triple point to temperatures of 1000K and nitrogen as indicated by comparison to experimental shock tube data. Constraints regarding the structure of the equation ensure reasonable extrapolated properties up to temperatures and pressures less than 5000K and 25 Gpa. For typical calibration applications, the new reference equation is supplemented by a simple but also highly accurate fromulation, valid only for supercritical nitrogen between 250 and 350 K at pressures up to 30 Mpa.
International Journal of Thermophysics
No. 4


caloric properties, density, equation of state, fundamental equation, nitrogen, thermodynamic properties


Span, R. , Lemmon, E. , Jacobsen, R. and Wagner, W. (1998), A Reference Quality Equation of State for Nitrogen, International Journal of Thermophysics (Accessed April 22, 2024)
Created June 30, 1998, Updated October 12, 2021