Compressibilities of ternary mixtures C1-nC16-CO2 under pressure from ultrasonic measurements of sound speed

Abstract

Speed of sound measurements have been performed on three mixtures of the ternary system methane + carbon dioxide + normal hexadecane. The systems have been investigated from 12 to 70 MPa in the temperature range from 313 to 393 K. Furthermore, these measurements have allowed the evaluation of the isothermal and the isentropic compressibilities up to 70 MPa from low pressure (<40-MPa) density data.KEY WORDS: compressibility; equation of state; high pressure; speed of sound.

In Pursuit of a High-Temperature, High-Pressure, High-Viscosity Standard: The Case of Tris(2-ethylhexyl) Trimellitate

“…High-pressure density data were obtained from speed of sound measurements by integration of the Newton Laplace equation (13) where α P is the isobaric expansion coefficient and C P the heat capacity at constant pressure. The integration was performed numerically using a predictor corrector 27 that requires density and heat capacity at atmospheric pressure to initiate the iterative procedure. The density data at atmospheric pressure (0.1 MPa) were obtained from U-tube densimeter measurements.…”

“…Bazile et al have also independently calculated the density of TOTM from their speed-of-sound measurements performed at temperatures from 293 to 373 K and at pressures up to 200 MPa on lot C. Speed of sound measurements can be used directly in the formulations of equations of state, can also be used to derive precise density data, and have been especially useful here in obtaining the density of the liquid at high pressures. ,, The expanded uncertainty for speed of sound measurements within the 95% confidence level is 0.06% between 0.1 and 100 MPa and 0.2% between 100 and 200 MPa. The estimated uncertainty in the density at 95% confidence level is 0.2%.…”

“…Speed of sound measurements on TOTM were carried out at the University of Pau using a pulse-echo technique operating at 3 MHz. The apparatus, which has been described previously, ,, is essentially made up of an acoustic sensor composed of one piezoelectric disk facing two reflectors fixed at different positions. This acoustic sensor is located within a high pressure vessel connected to a volumetric pump that allows generating pressure up to 200 MPa.…”

Speeds of Sound and Densities of Ternary and Quaternary Mixtures of Tetralin, Decalin, n-Decane, and n-Hexadecane: Experiments and Thermodynamic Modeling with PC-SAFT Equation of State

“…4 The evaluation of improvement in these models depends on the reliability and diversity of the experimental data. 5 The speed of sound, which can also be considered as a thermodynamic quantity, 6 due to its close linkage to certain volumetric and isentropic properties of fluids, can be used as supporting information in comparative tests of different equations of state. 2 As discussed in previous works, in petroleum research, tetralin is a reference aromatic compound used as a surrogate to naphtha and kerosene fractions, 7 decalin is a reference naphthenic compound in diesel and kerosene fractions, 8 while n-decane and n-hexadecane are linear alkanes used to simulate kerosene and diesel fractions, respectively.…”

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In this work, speeds of sound for ternary and quaternary mixtures composed of tetralin, decalin, n-decane, and n-hexadecane were experimentally determined at pressures of 0.1,5,10,15,20, and 25 MPa and temperatures of 313.15, 323.15, and 333.15 K. Additional density data at atmospheric pressure for the same systems were measured experimentally at temperatures of 313.15, 323.15, and 333.15 K. From these results and thermodynamic definitions, densities at high pressures were calculated. The experimental data were correlated with the PC-SAFT equation of state.

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