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Joule‐Thomson effects in gas mixtures: The nitrogen‐methane‐ethane system
Author(s) -
Ahlert R. C.,
Wenzel L. A.
Publication year - 1969
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.690150224
Subject(s) - virial coefficient , thermodynamics , joule–thomson effect , virial theorem , methane , chemistry , equation of state , real gas , ternary operation , nitrogen , joule (programming language) , physics , quantum mechanics , organic chemistry , galaxy , computer science , programming language , power (physics)
Pressure‐temperature data were obtained along isenthalps for nitrogen, methane, and three ternary nitrogen‐methane‐ethane mixtures. These data were differentiated to obtain Joule‐Thomson coefficients over the temperature range from ambient to 200°K. and at pressures from 165 atm. to about 5 atm. Data for nitrogen was obtained down to 140°K. The resulting Joule‐Thomson coefficients were compared with predictions based on the Beattie‐Bridgeman and Benedict‐Webb‐Rubin equations of state and on the virial equation of state truncated after the third virial coefficient. These comparisons show that the Benedict‐Webb‐Rubin equation could predict the data with a deviation averaging 1.7%. The Beattie‐Bridgeman predictions were highly dependent upon the mixture rules used, with the best set of mixture rules giving an absolute average deviation of 4.8%. Predictions using the virial equation with virial constants obtained from the Lennard‐Jones potential energy function using a geometric mean minimum potential energy deviated from the experimental data by 5%. In all of these comparisons, the virial coefficients of ethane appear to be in greatest uncertainty, and the predictions of mixture data high in ethane least satisfactory. Thus it appears that improved data on the pure components, particularly ethane, are vital to any satisfactory evaluation of mixture properties.