| The potential boom in the global hydrogen economy will increase the need for accurate hydrogen thermodynamic property standards. Based on these needs, new fundamental equations of state for parahydrogen and normal hydrogen were developed to replace the existing standards. To accurately predict thermophysical properties near the critical region and in liquid states, the Quantum Law of Corresponding States was applied to predict the vapor pressure curve for normal hydrogen and selected single phase data on the normal hydrogen surface. Once adequacy of the theory was established, pure orthohydrogen data were predicted and an orthohydrogen equation of state was developed.; All three equations of state have the same maximum pressure of 2000 MPa and temperature of 1000 K. The uncertainty in density is 0.04% in the region between 250 and 450 K at and pressures from 0.1-300 MPa. The uncertainties of vapor pressures and saturated liquid densities vary from 0.1-0.2%. |
