Empirical models for the density and the viscosity of squalane (C30H62; 2,6,10,15,19,23-hexamethyltetracosane) have been developed based on an exhaustive review of the data available in the literature and new experimental density and viscosity measurements carried out as a part of this work. The literature review showed there was a substantial lack of density and viscosity data at high temperature (373 to 473) K and high pressure conditions (pressures up to 200 MPa). These gaps were addressed with new experimental measurements carried out at temperatures of (338 to 473) K and at pressures of (1 to 202.1) MPa. The new data were utilized in the model development to improve the density and viscosity calculation of squalane at all conditions including high temperatures and high pressures.The model presented in this work reproduces the best squalane density and viscosity data available based on a new combined outlier and regression algorithm. The combination of the empirical models and the regression approach resulted in models which could reproduce the experimental density data with average absolute percent deviation of 0.04%, bias of 0.000%, standard deviation of 0.05%, and maximum absolute percent deviation of 0.14% and reproduce the experimental viscosity data with average absolute percent deviation of 1.4%, bias of 0.02%, standard deviation of 1.8% and maximum absolute percent deviation of 4.9% over a wide range of temperatures and pressures. Based on the data set used in the model regression (without outliers), the density model is limited to the pressure and temperature ranges of (0.1 to 202.1) MPa and (273 to 525) K, while the viscosity model is limited to the pressure and temperature ranges of (0.1 to 467.0) MPa and (273 to 473) K. These models can be used to calibrate laboratory densitometers and viscometers at relevant hightemperature, high-pressure conditions.
The viscosity and density of aqueous solutions of carbon dioxide having mole fractions of CO 2 of 0.0086, 0.0168, and 0.0271 are reported. The measurements were made in the single-phase compressed liquid region at temperatures between (294 and 449) K at pressures up to 100 MPa; additional density measurements were also made at T = 274 K in the same pressure range. The viscosity was measured with a vibrating-wire viscometer while the density was measured by means of a vibrating U-tube densimeter; both were calibrated with pure water and either vacuum or ambient air. The density data have an expanded relative uncertainty of 0.07 % with a coverage factor of 2. From the raw data, the partial molar volume of CO 2 in aqueous solution has been determined and correlated as an empirical function of temperature and pressure. When combined with the IAPWS-95 equation of state of pure water, this correlation represents the measured densities of under-saturated solutions of CO 2 in water within ± 0.04 %. The viscosity data have an expanded relative uncertainty of 1.4 % with a coverage factor of 2. A modified Vogel− Fulcher−Tamman equation was used to correlate the viscosity as a function of temperature, pressure, and mole fraction of CO 2 with an absolute average relative deviation of 0.4 %. The viscosity and density of saturated aqueous solutions of CO 2 may be calculated by combining the correlations presented in this work with a suitable model for the mole fraction of CO 2 at saturation.
In order to design
safe and effective storage of anthropological
CO2 in deep saline aquifers, it is necessary to know the
thermophysical properties of brine–CO2 solutions.
In particular, density and viscosity are important in controlling
convective flows of the CO2-rich brine. In this work, we
have studied the effect of dissolved CO2 on the density
and viscosity of NaCl and CaCl2 brines over a wide range
of temperatures from 298 to 449 K, with pressures up to 100 MPa, and
salinities up to 1 mol·kg–1. Additional density
measurements were also made for both NaCl and CaCl2 brines
with dissolved CO2 at salt molalities of 2.5 mol·kg–1 in the same temperature and pressure ranges. The
viscosity was measured by means of a vibrating-wire viscometer, while
the density was measured with a vibrating U-tube densimeter. To facilitate
the present study, the theory of the vibrating-wire viscometer has
been extended to account for the electrical conductivity of the fluid,
thereby expanding the use of this technique to a whole new class of
conductive fluids. Relative uncertainties were 0.07% for density and
3% for viscosity at 95% confidence. The results of the measurements
show that both density and viscosity increase as a result of CO2 dissolution, confirming the expectation that CO2-rich brine solutions will sink in an aquifer. We also find that
the effect of dissolved CO2 on both properties is sensibly
independent of salt type and molality.
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