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Optimum mixture compositions for measurement of cross virial coefficients
Author(s) -
Eubank Philip T.,
Hall Kenneth R.
Publication year - 1990
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690361106
Subject(s) - virial coefficient , binary number , virial theorem , chemistry , thermodynamics , random error , composition (language) , analytical chemistry (journal) , component (thermodynamics) , statistics , mathematics , chromatography , physics , quantum mechanics , linguistics , philosophy , arithmetic , galaxy
Random error propagation is examined to determine cross second and third virial coefficients from binary gas density measurements by both the indirect and direct methods. Determination of the cross second virial coefficient B 12 from B m at a single composition via the indirect method is optimized when y 1 2e 1 = y 2 2e 2 , where e 1 and e 2 are the pure component uncertainties. When all errors are equal, the equimolar mixture is optimum as expected. Corresponding analysis of the cross third virial coefficients, C 112 and C 122 , show that the optimum compositions are not (frac13;, frac23;) as expected for equal error distribution, but rather (frac14;, frac34;). Equations presented allow determination of the two optimum compositions, when e m varies with composition. Minimization of the combined errors in B 12 , C 112 , and C 122 via mixture measurements at two compositions provides results near (frac13;, frac23;), when all errors are equal. Methods for direct measurement of B 12 are reexamined. Optimal compositions are found using third virial coefficient correlations.