Thermodynamic Properties of Oxygen, Nitrogen, and Air at Low Temperatures

The proper engineering design of modern low-pressure tonnage oxygen plants requires data on the thermodynamic properties of oxygen, nitrogen, and air that are more accurate than those previously available from charts. In this paper, new temperature-entropy diagrams of suitable scale are presented for these materials over a range of temperatures and pressures adequate for the purpose. These diagrams are calculated from literature data on zero-pressure heat capacity and latent heats of vaporization, and from a reduced equation of state which was obtained from a correlation of literature data on volumes, Joule-Thomson coefficients, and velocity-of-sound measurements.