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National Advisory Committee for Aeronautics, Technical Notes - Thermodynamic Properties of Gaseous Nitrogen

The tables of thermal properties of molecular nitrogen that have
been prepared in an NBS-NACA series hare been grouped together herein
for convenient use. They include the thermodynamic functions for the
gas, both real and ideal, the transport properties for the gas, and the
vapor pressure of the liquid and the solid. A table of the ideal~gas
properties is presented, including the specific heat at constant pres—
sure, enthalpy, entropy, and the free-energy function; and a table giving
these same properties for atomic nitrogen is also included. The tables
of the real-gas thermodynamic properties include density, compressibility
factor, entropy, enthalpy, specific heat at constant pressure, ratio of
specific heats, and velocity of sound at very low frequency.

For the tables of real—gas thermodynamic properties the entries are
for pressures of 0.01, 0.1, 0.1+, 0.7, 1, 11-, 7, 10, no, 70, and 100 atmos—
pheres. The temperatures cover the range from 1000 K, or slightly above,
up to 5,0000 K. The method of correlation of the pressure-volume—
temperature data permits the calculation of tables far beyond the range
of the experimental points. This is accomplished, with some sacrifice
of fit in certain regions, by the assumption of a reasonable represen—
tation of the forces within clusters of molecules.

Tables are also included for the viscosity, thermal conductivity,
and Prandtl number. The viscosity is tabulated as a function of pressure,
the low-pressure values having been computed on the basis of the force
constants e/k = 91.460 K and r0 = 3.681 A for the Lennard-Jones

6-12 model (where e is.the maximum energy of binding between molecules,
k is Boltzmann’s constant, and r0 is the classical distance of closest
intermolecular approach). The thermal conductivity was fitted to a purely
empirical equation, and the Prandtl number was computed in a straight—
forward manner from these and the specific—heat values.

The vapor pressure for nitrogen is given in a table with values at
every 20 from 52° to 1260 K for ready reference and with the values of
loglo P tabulated against uniformly spaced values of l/T to allow
accurate interpolation (where P is pressure and T is absolute temper-
ature). The latent heat of vaporization is also given for the tempera-
ture range 620 to 780 K.