Vapor-liquid equilibrium of carbon dioxide with isobutane and n-butane: Modified leung-griffiths correlation and data evaluation

Abstract

The Leung-Griffiths model as modified by Moldover and Rainwater is used to correlate high-pressure vapor-liquid equilibria of mixtures of carbon dioxide with n-butane and isobutane. Model correlations are compared against 10 independent experimental sources for these mixtures. Agreement is generally very good and comparable to mutual experimental discrepancies. The utility of the model as a data evaluation technique is demonstrated in that small suspect regions have been identified in certain data sets and the model predictions have been confirmed by subsequent measurements that agree with the model better than the earlier data.

A nonlinear correlation of high-pressure vapor-liquid equilibrium data for ethylene +n-butane showing inconsistencies in experimental compositions

“…A similar objective function is constructed for the T-p diagram (Fig. The correlation now achieves the level of agreement of previous fits to other mixtures [2][3][4][5][6][7][8]. Because of the evidence for errors in composition from the Michigan group as noted in Section 2, in this study we allowed the individual mixture compositions, as well as the mixture parameters of the model, to float as adjustable parameters.…”

“…Previously, we showed [5] that the data of Poettmann and Katz [12] on carbon dioxide + n-butane could be correlated consistently with a large number of more recent studies of that mixture, but only if their experimentally stated compositions were shifted. Previously, we showed [5] that the data of Poettmann and Katz [12] on carbon dioxide + n-butane could be correlated consistently with a large number of more recent studies of that mixture, but only if their experimentally stated compositions were shifted.…”