Viscosity and density measurements of compressed liquid dimethyl adipate using oscillating body techniques

The article reports viscosity measurements of compressed liquid dimethyl adipate obtained with a vibrating wire sensor. The vibrating wire instrument was operated in the forced, or steady-state, mode of oscillation. The viscosity measurements were carried out up to 20 MPa and at temperatures from (293 to 358) K. The required density of the liquid sample was obtained using a vibrating U-tube densimeter, model DMA HP, from Anton Paar GmbH. The measurements were performed in the temperature range (293–358) K and at pressures up to 25 MPa.The viscosity results were correlated with density, using a modified hard-spheres scheme. The root mean square deviation of the data from the correlation is less than 0.2%. The expanded uncertainty of the present viscosity results is estimated as ±1% at a 95% confidence level.Independent viscosity measurements were performed, at atmospheric pressure, using an Ubbelohde capillary in order to compare with the vibrating wire results, extrapolated by means of the above mentioned correlation. The two data sets agree within ±0.6%, well within the mutual uncertainty of the experimental methods. No literature data could be found for the viscosity of dimethyl adipate at pressures above 0.1 MPa. As a consequence, the present viscosity results could only be compared upon extrapolation of the vibrating wire data to 0.1 MPa. The present extrapolated vibrating-wire results have a good agreement with the literature data at temperatures around 293 K. However, the absolute deviations of the literature results increase steadily with increasing temperature up to around +0.04 mPa s or +2.0%. For higher temperatures up to 358 K the absolute deviations are nearly constant, around +0.05 mPa s. The maximum relative deviation to literature data in the whole range of the present viscosity measurements was +4.2% at 358 K. The density results obtained in the present work agree with the literature data within ±0.1% in the temperature and pressure ranges of the measurements.

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