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Viscosity and density of isobutane measured in wide ranges of temperature and pressure including the near‐critical region
Author(s) -
Herrmann Sebastian,
Hassel Egon,
Vogel Eckhard
Publication year - 2015
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.14759
Subject(s) - isobutane , supercritical fluid , viscometer , thermodynamics , viscosity , equation of state , reduced properties , chemistry , physics , organic chemistry , catalysis
Accurate ηρpT data for isobutane were measured for nine isotherms between 298.15 and 498.15 K using simultaneously a vibrating‐wire viscometer and a single‐sinker densimeter. The maximum pressure was 93% of the saturated for subcritical isotherms and 30 MPa for supercritical isotherms. The density measurements are generally characterized by an uncertainty of ≤0.1%. Allocation errors for temperature and pressure influence significantly their uncertainty in the near‐critical region. A comparison with the equation of state by Bücker and Wagner shows agreement normally within ±0.1%. The near‐critical isotherm 410.15 K reveals differences to −3.7% exceeding the uncertainty of 1.9%. The uncertainty in viscosity is ≤0.3%. The comparison with the correlation of Vogel et al. yields deviations exceeding the uncertainty of the correlation (3%). The critical enhancement becomes evident for the near‐critical isotherm amounting to 1.4%. The new data will improve the viscosity surface correlation. © 2015 American Institute of Chemical Engineers AIChE J , 61: 3116–3137, 2015