Sofia K. Mylona

Reference Correlation of the Viscosity of Squalane from 273 to 373 K at 0.1 MPa

The paper presents a new reference correlation for the viscosity of squalane at 0.1 MPa. The correlation should be valuable as it is the first to cover a moderately high viscosity range, from 3 to 118 mPa s. It is based on new viscosity measurements carried out for this work, as well as other critically evaluated experimental viscosity data from the literature. The correlation is valid from 273 to 373 K at 0.1 MPa. The average absolute percentage deviation of the fit is 0.67, and the expanded uncertainty, with a coverage factor k = 2, is 1.5%.

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

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 ...

Transport Properties of Fluids

Transport processes are the processes whereby mass, energy, or momentum are transported from one region of a material to another under the influence of gradients of velocity, temperature, or composition. They are characterized respectively by viscosity, thermal conductivity and diffusion coefficients, and their introduction forms the first part of this chapter. A brief discussion of the molecular theory describes what is known and what can be predicted. Accurate measurements are necessary and therefore current techniques are briefly presented. The chapter is concluded with a discussion of current reference values for the viscosity, thermal conductivity and diffusion coefficients employed for the calibration of instruments.

Reference Correlations of the Thermal Conductivity of o-Xylene, m-Xylene, p-Xylene, and Ethylbenzene from the Triple Point to 700 K and Moderate Pressures

This paper contains new, representative reference equations for the thermal conductivity of o-xylene, m-xylene, p-xylene, and ethylbenzene. The equations are based in part upon a body of experimental data that has been critically assessed for internal consistency and for agreement with theory whenever possible. In the case of the dilute-gas thermal conductivity, a theoretically based correlation was adopted in order to extend the temperature range of the experimental data. Moreover, in the critical region, the experimentally observed enhancement of the thermal conductivity is well represented by theoretically based equations containing just one adjustable parameter. All four correlations are applicable for the temperature range from the triple point of each fluid to 700 K, and an upper pressure limit determined by the maximum density limit for the equation of state used to provide density. At the upper temperature limit of 700 K, the maximum pressure was 200 MPa for m-xylene and p-xylene, but 60 and 70 MPa for ethylbenzene and o-xylene, respectively. At lower temperatures, the maximum pressure is lower. The overall uncertainty (at the 95% confidence level) of the correlations of the thermal conductivity of o-, m-, p-xylene, and ethylbenzene, over their range of applicability, varies for each fluid. For o-xylene, we estimate the uncertainty for liquid and supercritical densities for temperatures from the triple point to 400 K to be 2.6%, and 4% at higher temperatures, and in the dilute-gas region we estimate the uncertainty to be 2%. For m-xylene, the estimated uncertainty for liquid and supercritical densities at temperatures from the triple point to 375 K is 3.6%, and 5% at higher temperatures, and 6% for the dilute gas. For p-xylene, the estimated uncertainty for liquid and supercritical densities at temperatures from the triple point to 700 K is 3.6%, and 2.5% for the dilute gas. Finally, for ethylbenzene the estimated uncertainty for liquid and supercritical densities at temperatures from the triple point to 400 K is 2.8%, and 2.5% in the dilute-gas region. Uncertainties in the critical region for all four fluids are much larger, since the thermal conductivity approaches infinity at the critical point and is very sensitive to small changes in density.

Reference correlations for the viscosity and thermal conductivity of fluids over an extended range of conditions: hexane in the vapor, liquid, and supercritical regions (IUPAC Technical Report)

Abstract This article summarizes the correlation procedures developed for IUPAC Project 2012-040-1-100 [Reference correlations for the thermal conductivity and viscosity of fluids over extended range of conditions (vapor, liquid and supercritical regions)]. This project is focused on the development of wide-range reference correlations for the thermal conductivity and viscosity of fluids that incorporate as much theoretical knowledge of these properties as possible. The thermal conductivity and viscosity correlations developed here for pure fluids are functions of temperature and density. The best available equations of state for a given fluid are used to calculate the thermodynamic properties required for these correlations, often from measured temperatures and pressures. The correlation methodology developed during this project has been applied to hexane in this report but can be applied to any pure fluid with a reliable equation of state and reliable data for the thermal conductivity and viscosity over a significant range of temperatures and densities.