Improved Methods for Gas Mixture Viscometry Using a Vibrating Wire Clamped at Both Ends

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• 作者：Clayton R. Locke ; Paul L. Stanwix ; Thomas J. Hughes ; Austin Kisselev ; Anthony R. H. Goodwin ; Kenneth N. Marsh ; Eric F. May
• 刊名：Journal of Chemical & Engineering Data
• 出版年：2014
• 出版时间：May 8, 2014
• 年：2014
• 卷：59
• 期：5
• 页码：1619-1628
• 全文大小：468K
• 年卷期：v.59,no.5(May 8, 2014)
• ISSN：1520-5134

文摘

We present a clamped vibrating-wire instrument and the associated methods of measurement and analysis that enabled gas-mixture viscosity measurements at densities up to 110 kg路m^鈥? with a standard uncertainty of 0.09 渭Pa路s, which is a relative uncertainty of 0.60 %. The vibrating-wire was clamped at both ends and operated in the steady-state mode to make the apparatus more compact and allow operation over a broad range of conditions. New modifications to the method include an interleaved measurement protocol to minimize errors arising from fluctuations in temperature and pressure, and optimization of the signal-to-noise while ensuring that the driven wire鈥檚 response remained in the linear regime. The wire鈥檚 radius was determined from calibration measurements with He, and the viscometer鈥檚 performance was verified with N₂, CO₂, and CH₄. The discrepancies between the measured pure fluid viscosities and those predicted with models implemented in the software REFPROP 9.1 were smaller than 1 %; literature data for these fluids exhibit similar deviations. Viscosities of (1 鈥?x)C₃H₈ + xCH₄ with x = 0.9452, and (1 鈥?x)CO₂ + xCH₄ with x = 0.57 were also determined at pressures between (1.5 and 6.5) MPa and temperatures of (280, 303 and 328) K. The largest rms deviation of 3.6 % of the measured viscosities relative to those calculated with the extended corresponding states model implemented in REFPROP occurred for CH₄ + CO₂ at a temperature of 328 K.