Capillary Viscometer and Vibrating Tube Densimeter for Simultaneous Measurements up to 70 MPa and 423 K

Abstract

New equipment has been designed and constructed to simultaneously measure dynamic viscosity and density on the basis of capillary flow technique and vibrating tube method, respectively, up to 70 MPa and 423.15 K. This apparatus has been built taking into account a number of physical parameters such as volumetric flow, length, and inner radius of the capillary tube and border effects. On the basis of the results of this work, densities for liquids are measured with relative combined expanded uncertainties of 0.07 % for water and ethanol, 0.7 % for hexane, 0.2 % for heptane, and 0.17 % for 1-pentanol and 1-heptanol. For the dynamic viscosity, the corresponding relative combined expanded uncertainties are 0.7 % for water and ethanol, 4.0 % for hexane, and 1.1 % for heptane, 1-pentanol, and 1-heptanol. In the calculated uncertainty for density and dynamic viscosity was included the contribution of the sample impurity. Experimental determinations of both dynamic viscosities and densities are performed, for several pure liquids, at the same conditions of temperature, pressure, and volumetric flow and recorded by means of an electronic device. Data reliability has been verified comparing the measured values with the available literature data for carbon dioxide, water, heptane, and ethanol up to 353 K and 30 MPa. The maximum deviations of the measured data compared to the literature data are ± 3 μPa•s for dynamic viscosity and ± 0.25 kg•m −3 for density. Furthermore, new experimental data are reported for hexane, 1-pentanol, and 1-heptanol up to 353 K and 30 MPa with a combined expanded uncertainty mentioned before.

Simultaneous Measurement of Dynamic Viscosity and Density of n-Alkanes at High Pressures

“…A schematic diagram of the measuring a Combined uncertainties u c are u c (P) = 0.002 MPa, u c (T) = 0.007 K; relative combined uncertainty for isothermal compressibility, u rc (K T ) = 0.012 and for isobaric thermal expansivity u rc (α P ) = 0.006; the relative combined expanded uncertainty with a 0.95 level of confidence (k = 2) for the density, U rc (ρ exp ) = 0.0013 and for dynamic viscosity, U rc (η exp ) = 0.009. system is shown in Figure 1. 9 Briefly, the instrument consists of a syringe pump (SP), which has a standard uncertainty of 1 × 10 −4 cm 3 •min −1 , a vibrating tube densimeter (VTD), with a standard uncertainty of 0.2 kg•m −3 , two pressure indicators (TRP1 and TRP2) placed at the ends of the capillary tube, with a standard relative uncertainty of 0.02%, two temperature indicators placed on the side of the capillary tube and in the VTD, with a standard uncertainty of 0.005 K, three temperature regulators which maintain the temperature with stability of 0.004 K (capillary tube, VTD, and cylinders containing the fluid under study), and an electronic data acquisition unit. The length and internal radius of the capillary tube and its respective standard deviation are 7.550 × 10 −1 m ± 1 × 10 −3 m and 1.259 × 10 −4 m ± 7 × 10 −7 m, respectively.…”

“…The operating procedures of the apparatus, as well as more detailed information on the experimental equipment is detailed in our previous work. 9 Viscosity Measurements. The dynamic viscosity was measured using the capillary flow technique.…”

“…7 The knowledge of the density at different temperature and pressure conditions is not only necessary in many industrial applications, is also essential for the calculation of properties such as solubility or viscosity, both important for simulating the behavior of the fluid under reservoir conditions, and for testing the effectiveness of empirical models. 8 Recently, 9 we had reported the design of an instrument capable of simultaneously determining the dynamic viscosity and the density of liquid fluids, which we use to carry out experimental measurements of these same thermophysical properties of alkanes and alcohols up to 353 K and 30 MPa. In the present work, simultaneously measurements of the dynamic viscosity and the density of five alkanes in liquid phase (pentane, octane, nonane, decane and dodecane) at temperatures between 293 and 353 K and up to 30 MPa of pressure were performed.…”

Fluid properties at high pressures and temperatures: Experimental and modelling challenges

“…Among all the methods, capillary viscometers are well known and firmly established both in theory and in experimentation [33]. Interestingly, these viscometers have been adapted to operate at extremely high pressures.…”

A novel design of flow structure model for online viscosity measurement

“…In addition, the rheological behaviour of the fluid cannot be easily included in the offline measuring process. Online methods, such as vibration viscometry [13,14] and rotating viscometry [15,17] , are able to measure the fluid viscosity without destroying the rheological behaviour of the fluid. For example, Etchart et al [17] successfully measured the viscosity of a fluid with obvious rheological behaviour using vibration viscometry, Janeiro et al [18] used vibration viscometry to achieve fluid impedance spectroscopy and Diogo et al [19] utilised vibration viscometry to measure fluid viscosity with different chemical components and temperatures.…”