Calculation of density, vapor pressure and heat capacity near the critical point by incorporating cubic SRK EoS and crossover translation

Abstract

With the emerging application of near-critical fluid, the subject of equation of state (EoS) covering the critical point is of great significance as the thermodynamic behavior of fluids near the critical point is different. Although many different EoSs are available for fluids at the moment, the ones which can give good quantitative results are still rare. Therefore, it is essential to have a suitable model for proper prediction of fluids behavior and their thermodynamic properties near the critical region. In this study, the crossover translation, which applies the asymptotic behavior of fluids and scaling laws near and far from the critical point, was used. Thermodynamic properties including density, vapor pressure and isochoric heat capacity of fifteen pure components in the saturated state and single-phase region on different isotherms were investigated near the critical point by Soave-Redlich-Kwong (SRK) equation of state and crossover SRK EoS and the results were compared with experimental data. According to the results, crossover SRK EoS predicted all of the mentioned properties with quantitative accuracy. The average absolute percent deviation (AAPD) of the saturated liquid density, saturated vapor density, density on isotherms, vapor pressure and isochoric heat capacity based on crossover SRK EoS were 0.0060,0.1287, 0.0171, 0.057 and 2.53, respectively.