Simultaneous measurement of fluids density and viscosity using HP/HT capillary devices (original) (raw)
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Development and Validation of Tandem Capillary Tubes Method to Measure Viscosity of Fluids
2019
The viscosity of working fluids is an essential thermophysical property to design heat exchanger, efficient processes, equipment, and simulation. Different types of conventional methods are used to measure the viscosity of fluids. The capillary tube method is based on the theoretical principle, and it is a reliable method. Nevertheless, it is tough to measure viscosity precisely because of problems involved in an equipment. In the present study, the tandem capillary tube method is proposed, and reliability of this method is explained. In this method, the pressure changes at the ends of the tube can be canceled, and the viscosity can be easily obtained from the Hagen-Poiseuille equation. A way to eliminate an effect of diameter difference between tubes is also proposed. The reliability and accuracy have been verified by comparing the measured viscosities of R134a to the reference values calculated by REFPROP ver.9.1. Most of the data agreed well within ±1.5 % deviation. These results...
A single channel capillary microviscometer
Microfluidics and Nanofluidics, 2013
We have developed a microviscometer analyzing the fluid dynamics in a single channel glass microfluidic chip with a closed end. The device is able to test sample volumes of a few microliters by inserting one drop in the inlet. The fluid enters the channel driven by capillary pressure and an optical sensor registers the motion. The equation that describes the fluid dynamics is function of the channel geometry, atmospheric pressure, fluid viscosity, and capillary pressure. Knowing the first two, the last parameters can be obtained as fitting parameters from the meniscus position as a function of time plot. We have successfully tested Newtonian fluids with different viscosities and capillary pressure. Keywords Microviscometer Á Glass micromachining Á Closed channel N. Morhell: Fellowship holder Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET) H.
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Viscosity-ratio measurements made with capillary viscometers exploit the accurate values of the viscosity of helium calculated ab initio. Accurate values of the argon-tohelium viscosity ratio are now used for primary acoustic gas thermometry and for the most accurate redeterminations of the Boltzmann constant. Accurate viscosity ratio measurements enable the calibration of laminar flow meters with surrogate gases and their use with process gases. We review ratio viscometers that comprise one, two, and four capillaries. A single capillary is a ratio viscometer when it is used to measure multiple gases sequentially, while two-and four-capillary viscometers are instruments intended for ratio measurements. We consider gases and Newtonian liquids, with a focus on the two-capillary gas viscometer and its extension to pressures up to 100 MPa. A single-capillary viscometer could measure the ratio (viscosity of liquid water)/(viscosity of gaseous helium) thereby reducing the uncertainty of the liquidviscosity scale relative to the international system of units.
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Journal of Computational and Theoretical Nanoscience, 2015
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