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- Viscosity of liquid diethylene, triethylene and tetraethylene glycols at moderately high pressures using a vibrating wire instrumentPublication . Pereira, Marta F. V.; Avelino, Helena Maria Da Nóbrega Teixeira; Caetano, Fernando; Fareleira, JoãoNew viscosity measurements of compressed liquid diethylene glycol (DiEG), triethylene glycol (TriEG) and tetraethylene glycol (TeEG) have been performed using a vibrating wire instrument operated in the forced oscillation mode. The measurements have been carried out in a range of pressures up to 70 MPa and temperatures from (293-363) K, covering a total range of viscosities from (3.46-1.15 x 10(2)) mPa.s. Complementary experimental density data were obtained for the same glycols using an Anton Paar vibrating U-tube densimeter. These measurements have been performed in a range of temperatures from about (283-363) K and at pressures up to about 70 MPa. The viscosity results were correlated with density, using a modified hard-spheres scheme. The experimental density data were correlated, as a function of temperature and pressure, with a modified Tait-type equation. The expanded uncertainty of the present viscosity results at a 95% confidence level is estimated to be less than +/- 2.0% for viscosities up to 68 mPa s and less than +/- 2.6% for higher viscosities. The densities have an expanded uncertainty of +/- 0.2% at a 95% confidence level. (C) 2018 Published by Elsevier B.V.
- In pursuit of a high-temperature, high-pressure, high-viscosity standard: the case of tris(2-ethylhexyl) trimellitatePublication . Wakeham, William A.; Assael, Marc; Avelino, Helena Maria Da Nóbrega Teixeira; Bair, Scott; Baled, Hseen O.; Bamgbade, Babatunde A.; Bazile, Jean-Patrick; Caetano, Fernando; Comunas, Maria J. P.; Daridon, Jean-Luc; Diogo, João C. F.; Enick, Robert M.; Fareleira, João; Fernandez, Josefa; Oliveria, M. Conceição; Santos, Tânica V. M.; Tsolakidou, Chrysi M.This paper presents a reference correlation for the-viscosity of tris(2-ethylhexyl) trimellitate designed to serve in industrial applications for the calibration of viscometers at elevated temperatures and pressures such as those encountered in the exploration of oil reservoirs and in lubrication. Tris(2-ethylhexyl) trimellitate has been examined with respect to the criteria necessary for an industrial standard reference material such as toxicity, thermal stability, and variability among manufactured lots. The viscosity correlation has been based upon all of the data collected in a multinational project and is supported by careful measurements and analysis of all the supporting thermophysical property data that are needed to apply the standard for calibration to a wide variety of viscometers. The standard reference viscosity data cover temperatures from 303 to 473 K, pressures from 0.1 to 200 MPa, and viscosities from approximately 1.6 to 755 mPa s. The uncertainty in the data provided is of the order of 3.2% at 95% confidence level, which is thought to be adequate for most industrial applications.