Two Crossover Soave-Redlich-Kwong Equations of State with Fully Analytical Crossover Functions for the Thermodynamic Properties of Carbon Dioxide

Kiselev’s crossover method based on the renormalization group theory is an effective way to incorporate the critical fluctuations into the classical model. Here, we combined Kiselev’s crossover method with the Soave-Redlich-Kwong (SRK) equation of state (EoS) to develop two crossover SRK EoSs (CSRK1 and CSRK2) in which two fully analytical crossover functions were used respectively to speed up the calculations. The thermodynamic properties of carbon dioxide (CO₂), including theVLEproperties, density, isobaric and isochoric heat capacity, and speed of sound, were investigated using the two crossover SRK EoSs and the original SRK EoS. Finally, the performances of the CSRK1, CSRK2, and SRK EoS were compared and analyzed, which reveals that two crossover EoSs correct the description of the SRK EoS in the critical region. ForVLEandpVTproperties, both the crossover EoSs improve the original SRK EoS largely. However, the performances of CSRK2 in predicting the second-order derivative properties of CO₂are inferior to CSRK1.