An Absolute Viscometer-Densimeter and Measurements of the Viscosity of Nitrogen, Methane, Helium, Neon, Argon, and Krypton over a Wide Range of Density and Temperature
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- 作者：C. Evers ; H. W. L枚sch and W. Wagner
- 关键词：argon ; density ; helium ; krypton ; magnetic suspension coupling ; methane ; neon ; nitrogen ; simultaneous viscosity and density measurement ; single ; sinker densimeter ; viscometer ; viscosity
- 刊名：International Journal of Thermophysics
- 出版时间：2002
- 出版年：2002
- 期刊代码：33_0195928X
- 类别：ch
- 卷：23
- 期：6
- 页码：1411-1439
- 数据来源：sp
摘要
An apparatus for the simultaneous measurement of viscosity and density of fluids is presented. The viscometer-densimeter covers a viscosity range up to 150 µPas and a density range up to 2000 kgm–3 at temperatures from 233 to 523 K and pressures up to 30 MPa. Very accurate density measurements with uncertainties of ±0.02 to ±0.05%have always been carried out with this apparatus, although in its first version it was necessary to calibrate the viscosity measuring system on a reference fluid in order to achieve uncertainties of ±0.6 to ±1.0%in viscosity. After significant improvements, the apparatus now achieves uncertainties in viscosity of less than ±0.15%in the dilute gas region and less than ±0.4%for higher densities. Moreover, the viscosity measuring system can be described in an absolute way; calibration is no longer necessary. In order to test the advanced apparatus and to determine viscosity-density values of very high quality, comprehensive measurements on nitrogen, argon, and methane were carried out in the entire working range of the viscometer-densimeter. In addition, viscosity-density measurements on helium, neon, and krypton were made on two selected isotherms each. All measurements show that the estimated total uncertainty of ±0.15 to ±0.4%in viscosity and of ±0.02 to ±0.05%in density is clearly met. In order to verify the results of the combined viscometer-densimeter, a new apparatus for very accurate viscosity measurements was designed. While the working range of this apparatus is restricted to the dilute gas region, it yields uncertainties of less than ±0.07%in viscosity. Measurements carried out with this apparatus confirmed the previously measured values of the combined viscometer-densimeter within ±0.03%.