Weimer-Prausnitz method

Infinite dilution activity coefficients are predicted by several methods (4,5,10,27,28, 29,30,31). The most general are the Pierotti-Deal-Derr method (4), the parachor method (27), and the Weimer-Prausnitz method (10), modified by Hellpinstill and Van Winkle (28). Since accuracy is limited in these methods and noninfinite dilution conditions prevail in actual operations, the infinite dilution activity coefficients obtained should only be used for screening purposes. 

The Weimer-Prausnitz (WP) Method (10). Starting with the Hilde-brand-Schatchard model for nonpolar mixtures (34), Weimer and Praus-... 

The predictive techniques are rather accurate. However, significant errors have been observed in few cases (4, 13, 27, 40). No direct comparison between the three predictive methods is available. The authors of the parachor method (27) claim that their method yields equal or better results than the PDD method for the cases considered in their study it is believed (42), however, that the latter is more reliable and it is recommended. The Weimer-Prausnitz method probably gives less accuracy than the PDD method, but it is more general. For example, Hanson and Van Winkle (40) report that their data on the hexane-hexene pair were not successfully correlated by the WP method. The Helpinstill-Van Winkle modification is recommended over the WP method. Recently, Null and Palmer (43) have presented a modification of the WP method which provides better accuracy but it is less general. The PDD method should be used cautiously when extrapolation with respect to temperature is used (27). When the GLC method is used, reliable results are expected. Evaluation of infinite dilution relative volatilities is recommended (36). 

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