To extend the PSRK (predictive Soave-Redlich-Kwong equation of state) model to vapor-liquid equilibria of polymer solutions, a new EOS-gE mixing rule is applied in which the term ∑ xi ln(b/bi) in the PSRK mixing rule...To extend the PSRK (predictive Soave-Redlich-Kwong equation of state) model to vapor-liquid equilibria of polymer solutions, a new EOS-gE mixing rule is applied in which the term ∑ xi ln(b/bi) in the PSRK mixing rule for the parameter a, and the combinatorial part in the original universal functional activity coefficient (UNIFAC) model are cancelled. To take into account the free volume contribution to the excess Gibbs energy in polymer solution, a quadratic mixing rule for the cross co-volume bij with an exponent equals to 1/2 is applied[bij1/2= 1/2(bi1/2+bj1/2)]. The literature reported Soave-Redlich-Kwong equation of state (SRK EOS) parameters ofpure polymer are employed. The PSRK model with the modified mixing rule is used to predict the vapor-liquid equilibrium (VLE) of 37 solvent-polymer systems over a large range of temperature and pressure with satisfactory results.展开更多
A homotopy-Newton hybrid method is proposed for predicting azeotropes, in which the set of homotopy equations with larger convergent domain is solved firstly to generate the better initial guess, then Newton algorithm...A homotopy-Newton hybrid method is proposed for predicting azeotropes, in which the set of homotopy equations with larger convergent domain is solved firstly to generate the better initial guess, then Newton algorithm is used to solve the azeotrope equations. It has been proved through some illustrative examples that the hybrid method has concurrently the advantages of the wide range of convergence, flexible demand for initial guess and good smoothness of iterative process as the homotopy algorithm, and the rapid convergent speed and high accuracy as Newton′s method. So the hybrid method is a prospective approach to predicting the azeotropes of nonideal mixtures.展开更多
文摘To extend the PSRK (predictive Soave-Redlich-Kwong equation of state) model to vapor-liquid equilibria of polymer solutions, a new EOS-gE mixing rule is applied in which the term ∑ xi ln(b/bi) in the PSRK mixing rule for the parameter a, and the combinatorial part in the original universal functional activity coefficient (UNIFAC) model are cancelled. To take into account the free volume contribution to the excess Gibbs energy in polymer solution, a quadratic mixing rule for the cross co-volume bij with an exponent equals to 1/2 is applied[bij1/2= 1/2(bi1/2+bj1/2)]. The literature reported Soave-Redlich-Kwong equation of state (SRK EOS) parameters ofpure polymer are employed. The PSRK model with the modified mixing rule is used to predict the vapor-liquid equilibrium (VLE) of 37 solvent-polymer systems over a large range of temperature and pressure with satisfactory results.
文摘A homotopy-Newton hybrid method is proposed for predicting azeotropes, in which the set of homotopy equations with larger convergent domain is solved firstly to generate the better initial guess, then Newton algorithm is used to solve the azeotrope equations. It has been proved through some illustrative examples that the hybrid method has concurrently the advantages of the wide range of convergence, flexible demand for initial guess and good smoothness of iterative process as the homotopy algorithm, and the rapid convergent speed and high accuracy as Newton′s method. So the hybrid method is a prospective approach to predicting the azeotropes of nonideal mixtures.
