Improved Methods for Phase Density Prediction : Cob2s + Hydrocarbons�

Abstract

Improved methods for mixture phase density predictions were developed. First. scaling-law theory was introduced in the volume translation concept which results in simpler form and better representation for saturation densities of COz-hydrocarbon mixtures than that given by Peneloux's volume translation. Second. the scaled-variable-reducedcoordinate (SVRC) method was extended to the prediction of mixture densities. Using the extended SVRC correlation, mixture density predictions may be performed based on pure-fluid properties. or more precisely based on some mixture data. Both treatments gave comparable results with the existing methods in the literature with the added advantage of covering the full saturation range and obeying scaling-law behavior in the near-critical region. Generalized SVRC correlations provide adequate liquid and vapor density predictions (2 and 7% AAD. respectively). The quality of these predictions. however. is enhanced by the flexibility offered by one system-specific parameter.