Methods for refining the dependences for calculating the thermodynamic properties of gases based on cubic equations of state
The paper describes a procedure for refining the dependences for calculation of the thermodynamic properties, which are based on the cubic equations of state of a real gas. For this, formulas for calculating thermal and caloric coefficients are used. The calculation results for them are compared with the calculations for high-precision polynomial dependencies available in the monographs of the State Standard (Gosstandart of Russia). On the basis of a comparative analysis of the graphs, their difference is obtained, which is approximated by a correcting function that has a certain physical meaning. The corrected dependencies are checked in the process of multivariate analysis of the entire set of thermodynamic properties. The paper presents the software for the implementation of the described technique based on the equations of state of Redlich-Kwong, Soave-Redlich-Kwong, and Peng-Robinson.