The Joule-Thomson Effect and Heat Capacity at Constant Pressure for Air

The constants for air in the equation of state of Beattie and Bridgeman are evaluated from the p-v-T data of Holborn and Schultze, and this numerical equation is used to compute μCₚ at various temperatures and densities. From the Cₚ data at one atmosphere of the Reichsanstalt for air, corresponding values of Cₚ at the same temperatures and densities are calculated by means of the equation of state. The values of μ obtained from these two sets of calculations are plotted along isotherms against the corresponding pressures and the values at even pressures and various temperatures are in good agreement with the experimental data of Roebuck. The computed Cₚ data are compared with those of Roebuck and of Holborn and Jakob and are in good agreement with the values obtained by these experiments. The Joule-Thomson inversion curve obtained from the equation of state is in good agreement with the experimental values given by Roebuck.