Additional Density Measurements Research Articles

Extension of Vibrating-Wire Viscometry to Electrically Conducting Fluids and Measurements of Viscosity and Density of Brines with Dissolved CO2at Reservoir Conditions

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 w...

Viscosity and Density of Aqueous Solutions of Carbon Dioxide at Temperatures from (274 to 449) K and at Pressures up to 100 MPa

The viscosity and density of aqueous solutions of carbon dioxide having mole fractions of CO2 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 CO2 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 CO2 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 CO2 with an absolute average relative deviation of 0.4 %. The viscosity and density of saturated aqueous solutions of CO2 may be calculated by combining the correlations presented in this work with a suitable model for the mole fraction of CO2 at saturation.

Speed of Sound, Density, and Derivative Properties of Methyl Oleate and Methyl Linoleate under High Pressure

Speeds of sound were measured for methyl oleate and methyl linoleate (C15H30O2) at pressures up to 200 MPa along isotherms ranging from (283.15 to 393.15) K. Additional density measurements were carried out by using a U-tube densimeter up to 100 MPa from (293 to 393) K. From the integration of speed of sound, density was evaluated up to 200 MPa, and the isentropic compressibility was determined in the same p–T domain. A correlation that represents both the density and the speed of sound within their experimental uncertainties is reported to evaluate both the volume and its derivatives with respect to pressure (isothermal compressibility) and temperature (isobaric expansion).

The plasma density distribution in the inner region of Saturn's magnetosphere

Electron density measurements derived from the upper hybrid resonance frequency have been obtained from the Cassini Radio and Plasma Wave Science experiment over a 7 year period from 28 October 2004 through 7 November 2011. Additional density measurements inside the orbit of Enceladus and outside the orbit of Rhea have made it possible to expand a previously published density model to radial distances from 2.6 to 10.0 Saturnian radii (RS). The distribution of density data is compared to a simple scale height density model for a single‐species plasma within 8° of the magnetic equatorial plane. There is a broad peak in the equatorial density distribution between 4 RS and 5 RS with the plasma falling off both inward and outward from the peak region. The radial dependence of the equatorial density profile varies as R4.0 from 2.6 RS to 4 RS and as R–4.8 from 5 RS to 10 RS. The plasma distribution outside 5 RS remains consistent with earlier density models but additional density measurements inside 4 RS provide information on the plasma distribution in this inner region that will be the focus of the F‐Ring and proximal orbits near the end of the Cassini mission.

Profil épidémiologique et clinique des condylomes acuminés au cours de l’infection par le VIH au service de dermatologie-MST du CHU de Conakry (Guinée)

Speed of sound of fatty acid esters are relevant for the formulation of biodiesel fuels but data on this property are scarce on literature. In this work speeds of sound of three saturated fatty acid methyl esters (caprate, myristate, palmitate) two unsaturated (oleate, linoleate) as well as two fatty acid ethyl esters (caprate, myristate) were measured using a pulse echo technique operating at 3 MHz. The measurements were carried out at atmospheric pressure in the temperature range 283.15–373.15 K. Additional density measurements were performed in order to estimate the isentropic compressibility and the molecular compressibility. From these data, a group contribution method was developed to predict the molecular compressibility and speed of sound of both methyl and ethyl esters with an uncertainty of circa 0.1%.

Novel data and a group contribution method for the prediction of the speed of sound and isentropic compressibility of pure fatty acids methyl and ethyl esters

Speed of sound of fatty acid esters are relevant for the formulation of biodiesel fuels but data on this property are scarce on literature. In this work speeds of sound of three saturated fatty acid methyl esters (caprate, myristate, palmitate) two unsaturated (oleate, linoleate) as well as two fatty acid ethyl esters (caprate, myristate) were measured using a pulse echo technique operating at 3MHz. The measurements were carried out at atmospheric pressure in the temperature range 283.15–373.15K. Additional density measurements were performed in order to estimate the isentropic compressibility and the molecular compressibility. From these data, a group contribution method was developed to predict the molecular compressibility and speed of sound of both methyl and ethyl esters with an uncertainty of circa0.1%.

Speed of Sound, Density, and Derivative Properties of Fatty Acid Methyl and Ethyl Esters under High Pressure: Methyl Caprate and Ethyl Caprate

The speed of sound in methyl caprate (C11H22O2) and ethyl caprate (C12H24O2) was measured using a pulse echo technique operating at 3 MHz. The measurements were carried out at pressures up to 210 MPa in the temperature range (283.15 to 403.15) K. Additional density measurements were performed up to 100 MPa from (293 to 393) K. From these measurements, the density was evaluated up to 210 MPa, and the isentropic and isothermal compressibilities were determined in the same P–T domain.

Speed of Sound, Density, and Compressibility of Alkyl-Benzenes as a Function of Pressure and Temperature: Heptadecylbenzene and Octadecylbenzene

Measurements of speed of sound were carried out in liquid heptadecylbenzene and octadecylbenzene at pressures from atmospheric up to 150 MPa in the temperature range 303 to 383 K using a pulse technique operating at 3 MHz. Additional density measurements were performed up to 60 MPa. From these measurements, the density was evaluated up to 150 MPa and the isentropic and isothermal compressibilities were determined in the same P and T domain. The results were fitted to a Tait-like equation.

Compressibilities of liquid pentadecylcyclohexane and nonadecylcyclohexane from high pressure speed of sound and density measurements

The speed of sound in liquids pentadecylcyclohexane (C 21H 42) and nonadecylcyclohexane (C 25H 50) was measured by means of a pulse technique operating at 3 MHz. The measurements were carried out at pressures up to 150 MPa in the temperature range (303.15 to 383.15) K. Additional density measurements were performed up to p=60 MPa in the same range of temperature. From both measurements, the density was evaluated up to p=150 MPa and the isentropic compressibility was determined in the same pressure–temperature domain. The full density data were represented by a Tait-like equation in order to calculate the isothermal compressibility.

Speed of Sound and Some Thermodynamic Properties of Liquid Methylcyclopentane and Butylcyclohexane in a Wide Range of Pressure

Ultrasonic velocity measurements were performed on liquid methylcyclopentane and butylcyclohexane at pressures from atmospheric up to 150 MPa in the temperature range from 293 to 373 K using a pulse echo technique operating at 3 MHz. The data were used to evaluate various thermophysical properties such as density, and isentropic and isothermal compressibilities up to 150 MPa with the help of additional density measurements.

High-pressure speed of sound, density and compressibility of heavy normal paraffins: C 28H58 and C 36H 74

The speed of sound in the high molecular weight normal paraffins n - C 28H58 and n -C 36H 74was measured using a pulse technique operating at 3 MHz. The measurements were carried out at pressures up to 150 MPa in the temperature range 353.15 K to 403.15 K. The data were used to determine various thermophysical properties such as density, isentropic and isothermal compressibilities up to 150 MPa with the help of additional density measurements performed at atmospheric pressure.

High-pressure speed of sound and compressibilities in heavy normal hydrocarbons:n-C23H48andn-C24H50

The speed of sound in the normal hydrocarbonsn- C23H48andn- C24H50has been measured up to 150 MPa in the temperature range (293.15 to 373.15) K using a pulse technique operating at 3 MHz. The data have been used to evaluate various thermophysical properties such as density, and isentropic and isothermal compressibilities up to 150 MPa with the help of additional density measurements performed at atmospheric pressure.

Speed of sound, density, and compressibility of petroleum fractions from ultrasonic measurements under pressure

The speed of sound in a synthetic and a real distillation cut has been measured up top= 150 MPa in the temperature rangeT= (293.15to373.15) K. The synthetic system, which is representative of distillation cuts, is made up of five components with high boiling point temperatures of aboutTb= 523 K belonging to essential chemical families found in natural fluids {iso, or n-paraffins, naphthenes, and aromatics (alkybenzene, or alkylnaphtalene)}. The distillation cut comes from the separation of a standard crude oil by distillation aroundT= 523 K. The measurements allow the evaluation of various thermophysical properties such as densities, and isentropic and isothermal compressibilities up top= 150 MPa with the help of additional density measurements performed at atmospheric pressure.

Surface tension, heat capacity, and volume of amphiphilic compounds in formamide solutions

Density measurements of sodium dodecyl sulfate (SDS), sodium decyl sulfate (SDeS), sodium octyl sulfate(SOS), and sodium hexyl sulfate(SHS) in formamide (FA) as functions of the surfactant concentrations were carried out at 25°C. For SDS in FA, additional density measurements at 35 and 60°C and surface tension and specific heat capacity measurements at 25°C were also performed. From density and specific heat capacity data, the apparent molar volume and heat capacity of the surfactants as functions of concentration were calculated. The surface excess of SDS at the solution–air interface was also determined from the surface tension measurements using the Gibbs adsorption equation. Under our experimental conditions, none of the experimental results evidence micelle formation. In addition, volumetric studies of the hexanol–SDS–FA ternary system at 25°C evidence only interactions between the dispersed surfactant and alcohol.