Towards accurate prediction of thermodynamic properties of hydrogen over supercritical conditions using volume-translated cubic equations of state

Hydrogen is a clean energy source that helps reduce fossil fuel dependence, achieve net-zero emissions, and contribute to environmental sustainability. Accurate prediction of the thermodynamic properties of hydrogen plays a crucial role in the design and operation of various hydrogen-based systems. In this study, we propose improved distance-function-based volume translation models in Soave-Redlich-Kwong equation of state (SRK EOS) and Peng-Robinson equation of state (PR EOS) for hydrogen, resulting in the development of volume-translated SRK EOS and volume-translated PR EOS (i.e., VT-SRK EOS and VT-PR EOS). These models are capable of accurately predicting the thermodynamic properties of hydrogen under supercritical conditions (i.e., pressures from 0.01 MPa to 300 MPa and temperatures from critical temperature (i.e., 33.15 K) to 600 K). More specifically, the new VT-SRK EOS yields %AADs of 0.56, 2.07, 5.39, 5.69, 6.71, and 1.92 in predicting density, isobaric thermal expansivity, isothermal compressibility, isobaric heat capacity, isochoric heat capacity, and speed of sound, respectively. The proposed VT-PR EOS also performs well in predicting these six thermodynamic properties, with %AADs of 0.75, 2.68, 6.08, 6.28, 7.14, and 1.72, respectively. Additionally, the proposed volume-translated cubic equations of state (VT-CEOSs) reproduce the true critical volume of hydrogen. The proposed VT-SRK EOS and VT-PR EOS do not lead to the crossover of pressure-volume isotherms within the tested pressure and temperature ranges.