Opis: This paper discusses a mathematical model for computing the thermodynamic properties of propane, n-butane, isobutane, and their mixtures, in the fluid phase using a method based upon statistical chain theory. The constants necessary for computations such as the characteristic temperatures of rotation, electronic state, etc. and the moments of inertia are obtained analytically applying a knowledge of the atomic structure of the molecule. The paper presents a procedure for calculating thermodynamic properties such aspressure, speed of sound, the Joule-Thomson coefficient, compressibility, enthalpy, and thermal expansion coefficient. This paper will discuss, for the first time, the application of statistical chain theory for accurate properties of binary and ternary mixtures including propane, n-butane, and isobutane, in their entire fluid phases. To calculate the thermodynamic properties of Lennard-Jones chains, the Liu-Li-Lu model has been used. The thermodynamic properties of the hydrocarbon mixtures are obtained using the one-fluid theory. Ključne besede:statistical thermodynamics, chain theory, mixtures, transport properties, hydrocarbons, isobutane, n-butane, propane, refrigerants Objavljeno: 01.06.2012; Ogledov: 1345; Prenosov: 66 Povezava na celotno besedilo

Opis: The densities of ethanol and ethanol-water mixtures were measured with a vibrating tube densimeter at 25.0, 50.0 and 75.0°C in the pressure range from 0.10 to 40.00 MPa. Densities were correlated using an empirical model. Partial molar volumes, excess molar volumes, isothermal compressibilities, cubic expansion coefficients and internal pressures were calculated from obtained densities. This study reports the dependence of densities, partial molar volumes, excess molar volumes, isothermal compressibilities, cubic expansion coefficients and internal pressures on composition, temperature and pressure. Ključne besede:ethanol, ethanol-water mixtures, density measurements, vibrating U tube densimeter, partial molar volumes, isothermal compressibility, isobaric expansibility, cubic expansion coefficient, internal pressure Objavljeno: 01.06.2012; Ogledov: 1794; Prenosov: 73 Povezava na celotno besedilo

Opis: The note features the mathematical model of computing binary diffusion coefficient, thermal diffusion factor and viscosity in the real-gas region on the basis of nonequilibrium statistical mechanics. For the analytical calculation of transport properties, we have used the Kihara and Chapman-Cowling model up to the third order. In the presented note we calculated transport properties for mixtures between carbon monoxide and helium. We have developed the new mixing rules for the calculation of transport properties for mixtures. The analytical results obtained by statistical mechanics are compared with the experimental data and they show relatively good agreement. Ključne besede:thermodynamics, statistical thermodynamics, mathematical models, binary diffusion coefficient, thermal diffusivity, binary mixtures Objavljeno: 30.05.2012; Ogledov: 1551; Prenosov: 53 Povezava na celotno besedilo