Reference Correlations for the Density and Viscosity of Squalane from 273 to 473 K at Pressures to 200 MPa

Abstract

This paper presents new reference correlations for both the density and viscosity of squalane at high pressure. These correlations are based on critically evaluated experimental data taken from the literature. In the case of the density, the correlation, based on the Tait equation, is valid from 273 to 473 K at pressures to 200 MPa. At 0.1 MPa, it has an average absolute deviation of 0.03%, a bias of −0.01%, and an expanded uncertainty (at the 95% confidence level) of 0.06%. Over the whole range of pressures, the density correlation has an average absolute deviation of 0.05%, a bias of −0.004%, and an expanded uncertainty (at the 95% confidence level) of 0.18%. In the case of the viscosity, two correlations are presented, one a function of density and temperature, based on the Assael-Dymond model, and the other a function of temperature and pressure, based on a modified Vogel-Fulcher-Tammann equation. The former is slightly superior to the latter at high temperatures (above 410 K), whereas the reverse is true at low temperatures, where the viscosity is strongly temperature dependent. In the temperature range from 320 to 473 K at pressures to 200 MPa, the first correlation has an average absolute deviation of 1.41%, a bias of −0.09%, and an expanded uncertainty (at the 95% confidence level) of 3%. Below 320 K, deviations from the present scheme rise to a maximum of 20%. In the temperature range from 278 to 473 K at pressures to 200 MPa, the second viscosity correlation has an average absolute deviation of 1.7%, a bias of −0.04%, and an expanded uncertainty (at the 95% confidence level) of 4.75%.

New Experimental Data and Reference Models for the Viscosity and Density of Squalane

“…Very recently, Mylona et al 28 have published correlations of the density and viscosity of squalane based on their analysis of the available experimental data, including the new data presented in this paper. In their work, the density was correlated using the same model as in the present analysis; however, they set a2 = 0 and constrained C to the value 0.2.…”

Tris(2-ethylhexyl) trimellitate (TOTM) a potential reference fluid for high viscosity. Part I: Viscosity measurements at temperatures from (303 to 373) K and pressures up to 65 MPa, using a novel vibrating-wire instrument

“…In order to fulfil the need of an industrial viscosity standard for moderately high viscosity, a reference correlation for viscosity of squalane, from (3.13 to 83.90) mPa s, at 0.1 MPa and temperatures from (273 to 373) K was recently proposed by Comuñas et al [6], and for pressures up to 200 MPa, from (0.85 to 954) mPa s and temperatures from (273 to 473) K proposed by Mylona et al [10], being the first under the auspices of IATP and the second under the auspices of IUPAC (Project 2012-051-1-100). Recently, measurements of the viscosity of squalane have been published by Comuñas et al [9] in a very wide range of pressures (up to 350 MPa), in a temperature range from (293 to 363) K. It should be noted that DIDP was used as a calibrant in some of those viscosity measurements of squalane reported in Ref.…”

“…However those viscosity data were not used as primary data for the reference correlation of squalane reported in Ref. [10].…”

“…As a consequence, the International Association for Transport Properties (IATP) has been developing efforts in order to respond to the demand of industrial viscosity standards [1][2][3][4][5][6][7][8][9][10]. In particular, IATP has proposed an industrial viscosity standard for moderately high viscosity [DIDP] and, more recently, has created an internal project regarding the search of a high viscosity industrial viscosity standard fluid, and at high pressures and high temperatures.…”

“…As a consequence, there is, at present, a demand for new industrial viscosity standards with various viscosities, at high pressures and high temperatures. Industrial viscosity standards with adequate viscosity could be used for calibration and tests of industrial viscometers for use in-well, or on-line, at the adequate working conditions [1][2][3][4][5][6][7][8][9][10]. Since, in industry the range of viscosity of useful fluids varies over several orders of magnitude, a number of "industrial reference materials", covering a large spectrum of practical conditions, are required to calibrate or verify the calibration of those instruments [8].…”