Showing papers by "Azerbaijan State Oil Academy published in 2005"

Densities, apparent molar volumes and viscosities of concentrated aqueous NaNO3 solutions at temperatures from 298 to 607 K and at pressures up to 30 MPa

Abstract: Densities of four (2.124, 2.953, 5.015 and 6.271 mol-kg−1) and viscosities of eight (0.265, 0.503, 0.665, 1.412, 2.106, 2.977, 5.015 and 6.271 mol-kg−1) NaNO3(aq) solutions have been measured with a constant-volume piezometer immersed in a precision liquid thermostat and using capillary flow techniques, respectively. Measurements were made at pressures up to 30 MPa. The temperature range was 298–607 K for the density measurements and 298–576 K for the viscosity measurements. The total uncertainty of density, viscosity, pressure, temperature and composition measurements were estimated to be less than 0.06%, 1.6%, 0.05%, 15 mK and 0.02%, respectively. The temperature, pressure and concentration dependence of density and viscosity of NaNO3(aq) solutions were studied. The measured values of density and viscosity of NaNO3(aq) were compared with data and correlations reported in the literature. Apparent molar volumes were derived using the measured density values. The viscosity data have been interpreted in terms of the extended Jones–Dole equation for strong electrolytes. The values of the viscosity A-, B-, D- and F-coefficients of the extended Jones–Dole equation for the relative viscosity (η/η0) of NaNO3(aq) solutions were evaluated as a function of temperature. The derived values of the viscosity A- and B-coefficients were compared with the results predicted by Falkenhagen–Dole theory of electrolyte solutions and calculated with the ionic B-coefficient data.

Thermal Conductivity and Viscosity of Aqueous K2SO4 Solutions at Temperatures from 298 to 575 K and at Pressures up to 30 MPa

Abstract: The thermal conductivity of three (0.239, 0.499, and 0.782 mol·kg−1) and the viscosity of four (0.0658, 0.2055, 0.3050, and 0.4070 mol·kg−1) binary aqueous K2SO4 solutions have been measured with coaxial-cylinder (steady-state) and capillary-flow techniques, respectively. Measurements were made at pressures up to 30 MPa, and the range of temperature was 298–575 K. The total uncertainties of the thermal conductivity, viscosity, pressure, temperature, and composition measurements were estimated to be less than 2%, 1.6%, 0.05%, 30 mK, and 0.02%, respectively. The measured values of the thermal conductivity and viscosity of K2SO4 (aq) were compared with data and correlations reported in the literature. The reliability and accuracy of the experimental method was confirmed with measurements on pure water with well known (IAPWS standards) thermal conductivity and viscosity values (deviations, AAD, within 0.31 % and 0.52 %, respectively). The values of the viscosity A-, B-, and D-coefficients of the extended Jones–Dole equation for the relative viscosity (η/η0) of aqueous K2SO4 solutions as a function of temperature were studied. The maximum of the B-coefficient near 340 K has been found. The derived values of the viscosity A- and B-coefficients were compared with results predicted by the Falkenhagen–Dole theory of electrolyte solutions and calculated with the ionic B-coefficient data. The behavior of the concentration dependence of the relative viscosity of aqueous K2SO4 solutions is discussed in terms of the modern theory of transport phenomena in electrolyte solutions.

Viscosities of aqueous LiNO3 solutions at temperatures from 298 to 573 K and at pressures up to 30 MPa

Abstract: The viscosities of four (0.265, 0.493, 1.074, and 1.540 mol.kg -1 ) aqueous LiNO 3 solutions were measured in the liquid phase with a capillary flow technique. Measurements were made at four isobars (0.1, 10, 20, and 30 MPa). The range of temperatures was from 298 to 573 K. The total uncertainties of viscosity, pressure, temperature, and concentration measurements were estimated to be less than 1.5%, 0.05%, 15 mK, and 0.014%, respectively. The reliability and accuracy of the experimental method was confirmed with measurements on pure water for five selected isobars (1, 10, 20, 40, and 50 MPa) and at temperatures between 294.5 and 597.6 K. The experimental and calculated values from the International Association for the Properties of Water and Steam formulation for the viscosity of pure water show excellent agreement within their experimental uncertainty (AAD = 0.27%). The temperature, pressure, and concentration dependences of the relative viscosity (η/η 0 , where η 0 is the viscosity of pure water) were studied. The behavior of the concentration dependence of the relative viscosity of aqueous LiNO 3 solutions was discussed in light of the modern theory of transport phenomena in electrolyte solutions. The values of the viscosity A and B coefficients of the Jones-Dole equation for the relative viscosity (η/η 0 ) of aqueous LiNO 3 solutions as a function of temperature were studied. The derived values of the viscosity A and B coefficients were compared with the results predicted by the Falkenhagen-Dole theory of electrolyte solutions and calculated with the ionic B coefficient data. Different theoretical models for the viscosity of electrolyte solutions were stringently tested with new accurate measurements on LiNO 3 (aq). The predictive capability of the various models was studied. The measured values of the viscosity at atmospheric pressure were directly compared with the data reported in the literature by other authors.

Investigation of Characteristic Features of Critical Heat Transfer under Conditions of Boiling of Subcooled Hydrocarbons in a Close-to-Critical Pressure Range

Abstract: Results are given of an investigation of heat transfer under conditions of boiling of subcooled benzene and toluene at close-to-critical pressures in a vertical straight and horizontal coil pipes. A nonuniform distribution of the wall temperature along the perimeter of the horizontal coil pipe is revealed, as well as a smooth rise of this temperature under conditions of critical heat transfer. Equations are suggested for the calculation of critical heat flux in the pressure range identified above with the vertical position of the straight pipe.

New calcium-selective electrodes based on crown compounds bearing ester groups in the macrocyclic ring

Abstract: Calcium-selective electrodes (Ca-SEs) based on the geometric isomers of di-(1,2,3,6-tetrahydrobenzo)-crown esters bearing four ester fragments in the macrocyclic ring were prepared, and their electrochemical properties were studied. It was demonstrated that these electrodes offer promise for medical and biological studies and clinical medicine. The electrodes exhibit high selectivity at crown compound concentrations, ensuring the formation of a 1 : 1 Ca-ionophore complex in the membrane.

Vapor pressures and derived thermodynamic properties of aqueous Zn(NO3)2 solutions from 423.15 to 623.15 K

Abstract: Vapor pressures of aqueous Zn(NO3)2 solutions (0321, 0499, 0900, 1400, 2000, and 3002 mol kg–1) have been measured by the static method in the temperature range from 42315 to 62315 K with a constant‐volume piezometer immersed in a precision liquid thermostat The total uncertainty of temperature, pressure, and composition measurements were estimated to be less than 15 mK, 02%, and 0014%, respectively The vapor pressures of pure water were measured to confirm the accuracy of the method for aqueous Zn(NO3)2 solutions taken using the apparatus and procedure in this study The resulting measurements of PS ‐ TS for pure water were compared with values calculated from IAPWS formulation Useful thermodynamic functions (water and electrolyte activities, osmotic coefficient, excess relative partial molar entropy, and relative partial molar enthalpy values of solvent) were derived using measured values of vapor pressure for the solutions and pure water