화학공학소재연구정보센터
Inzynieria Chemiczna i Procesowa, Vol.24, No.2, 335-352, 2003
Modified equations of state with the Carnahan-Starling repulsive term
An analysis is presented of new equations of state composed of a repulsive term of the Carnahan -Starling type and an attractive term in the form of a rational quadratic function. Three generalized equations of state with two substance-dependent parameters (u, w) in the perturbation term were selected as a result of the preliminary analysis. The (u, w) coefficients were evaluated for 20 substances by an approximation from the reference thermodynamic data in the neighborhood of a critical isotherm. Linear relations (u, w) and (Z(C), Z(c)(eos)) were ascertained for each of the equations analyzed. Further computational tests performed on the lines of a vapour-liquid phase transition and on the isotherms revealed the best results for a CS3L2M0 equation, that is also numerically, stable. A method is also demonstrated for the estimation of the (u, w) parameters of the substances which lack thermodynamic data in the neighborhood of the critical isotherm.