The iPRSV equation of state

The Peng–Robinson cubic equation of state with the Stryjek–Vera modification (PRSV) is widely adopted in scientific studies and engineering. However, it is affected by a discontinuity in all the properties, which is caused by a discontinuity of the α-function. Aside of being non-physical, this discontinuity causes robustness and accuracy issues in numerical simulations. The discontinuity in thermodynamic properties is eliminated here without affecting the overall accuracy of the model. In addition, the functional form of α(T) is optimized in such a way that it is not required to change the values of the fluid-dependent parameters stored in the many available databases. The performance of the improved equation of state (iPRSV) is assessed by comparing calculated properties with those obtained with the original PRSV equation of state, the Gasem et al. equation of state (PRG), which is also continuous in temperature, a reference multiparameter equation of state, and experimental data. It is shown that the accuracy of the new model approaches the accuracy of the original equation of state and that it performs better than the PRG equation of state. The modified PRSV equation of state solves the issue of the artificial discontinuity in the calculation of properties relevant to scientific and industrial applications, at the cost of a small decrease in overall accuracy.