The predictive error in vapor pressure of
limited-data Wagner constants relative to that of entire-curve constants is
studied for eleven data intervals. Good
precision is assumed for data inputs, four digits in the mantissa of Ln Pv,r and five digits for Tr. An algebraic solution for the
fully-determined case based on only four data points is used to estimate Wagner
constants. Seventy-two species are used
to assess the impact of the location of the two interior points and the
location and width of the limited-data interval upon the error in predicted Pv,r due to data imprecision. Hydrogen, helium, R152a, and water are used to assess error due to
Wagner imperfection and compare predictive capability of the algebraic fully-determined
and regressed over-determined approaches.
The results indicate
that limited VLE data of good precision from reduced temperature intervals with
a width ≥ 0.1 and a lower bound ≤ 0.6 can generally provide reasonable VLE
predictions over the entire two-phase curve for pure substances, with average error of approximately 1%. It is shown that the algebraic,
fully-determined solution presented is
a viable tool for investigating the extensibility of limited-data Wagner
constants.
Wagner equation vapor-liquid equilibrium pure substances t* test least-squares regression fully-determined solution equation imperfection data imprecision
Primary Language | English |
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Subjects | Engineering |
Journal Section | Regular Original Research Article |
Authors | |
Publication Date | March 1, 2018 |
Published in Issue | Year 2018 |