L. R. Fokin

Equation of state and thermodynamic properties of saturated and superheated mercury vapors up to 1650 K and 125 MPa

Experimental data on the compressibility, sound velocity, and saturation pressures have been generalized for mercury vapor at densities <3 g/cm2 based on the equation of state with the second, third, and fourth virial coefficients. The virial coefficients have been calculated using the three-parameter Lennard-Jones potential m-6. The data have been generalized using the nonlinear weighted least-squares method. The parameters of the models and their enlarged error matrix taking into account random and systematic (in the first approximation) errors of the experimental data have been determined. Tables of thermodynamic properties of the saturated and superheated vapor have been calculated. The enthalpy drop error has been correctly calculated on the isentropic curve of the superheated vapor taking into account covariations of the equation of state parameters.

The Viscosity and Self-Diffusion of Rarefied Steam: Refinement of Reference Data

New experimental data on the viscosity of rarefied stem [1] confirm the prediction potentialities of the calculations of steam properties using the modified m-6-3 Stockmayer potential. Repeated processing is performed of experimental data on the viscosity and self-diffusion coefficient of steam in the temperature range from 280 to 1400 K, and refined tables of reference data for the properties under consideration are calculated.

Reliability of Data on the Thermophysical Properties of Materials: Three Examples

An analysis of data agreement as the main method for estimation of the reliability is performed for the thermophysical properties of matter using three examples: (1) the density of liquid mercury at 20°C, (2) the transport properties and the second virial coefficient of rarefied gases, and (3) the compressibility of alkali metal vapors at high temperatures and pressures.

The transport properties of an N2-H2 mixture of rarefied gases in the EPIDIF database

The principles of organization of the EPIDIF information-and-computation database are considered. Simultaneous processing of experimental data on the viscosity of pure components and mixture and on the coefficients of interdiffusion and thermal diffusion for a binary N2-H2 mixture of rarefied gases is performed. Nine parameters of three m-6 Lennard-Jones potentials of interaction of N2 and H2 molecules are determined within the least squares method. Tables of reference data for the considered transport properties are calculated in the temperature range from 100 to 1500 K and concentration range of 0–1(0.2). The parameters and their error matrix are included in the EPIDIF database.

Reference data on the viscosity of rarefied steam at a temperature of 2000 to 2500 K

An extensive array of experimental data on the coefficients of viscosity and self-diffusion of rarefied steam at temperatures ranging from 280 to 1773 K is fitted using relations of molecular kinetic theory and the generalized four-parameter Stockmayer potential. The parameters are found, namely, the collision diameterd = 2.495 Å, the depth of potential well ε = 689.7 K, the exponent of the repulsion branchm = 9, the dipole moment μ = 1.803 D, and their error matrix. The tables of reference data are calculated up to 2500 K. The estimates are suggested of their confidence errors, as well as the upper limit of the model validity with respect to temperature.

Calculating the melting curves by the thermodynamic data matching method: Platinum-group refractory metals (Ru, Os, and Ir)

A technique for reconstructing thermal properties, including the melting curve, of refractory metals based on the use of experimental data on caloric properties available up to the melting point and some regularities of the Debye–Grüneisen theory has been proposed. The calculation result is the consistent system of high-temperature thermal data, including the thermal expansion coefficient, solid-phase density, and volume jump upon melting. This technique was tried-out on refractory platinum-group metals based on experimental data on the enthalpy of the metals and confirmed by consistency with a thermodynamic calculation using shock-wave experiments and results obtained by the quantum molecular dynamics method.

Titanium Melting Curve: Data Consistency Assessment, Problems and Achievements

Experimental data for the thermodynamic properties of titanium on the melting curve in the pressure range from atmospheric value to 90 GPa are analyzed and brought into correspondence. The problems that have been considered are (i) the lack of data for the solid β-phase density near the normal melting point and (ii) the formation probability of a triple point on the melting curve for the coexisting β-, ω-, and liquid phases of titanium. To estimate the change of the volume upon melting 3d elements from Mendeleev’s periodic system, a correlation between the change of the volume, ΔVm, and the change of the entropy, ΔSm, on the melting curve at atmospheric pressure is suggested and effectively used.

Development of the system of reactor thermophysical data on the basis of ontological modelling

Compilation and processing of the thermophysical data was always an important task for the nuclear industry. The difficulties of the present stage of this activity are explained by sharp increase of the data volume and the number of new materials, as well as by the increased requirements to the reliability of the data used in the nuclear industry. General trend in the fields with predominantly orientation at the work with data (material science, chemistry and others) consists in the transition to a common infrastructure with integration of separate databases, Web-portals and other resources. This infrastructure provides the interoperability, the procedures of the data exchange, storage and dissemination. Key elements of this infrastructure is a domain-specific ontology, which provides a single information model and dictionary for semantic definitions. Formalizing the subject area, the ontology adapts the definitions for the different database schemes and provides the integration of heterogeneous data. The important property to be inherent for ontologies is a possibility of permanent expanding of new definitions, e.g. list of materials and properties. The expansion of the thermophysical data ontology at the reactor materials includes the creation of taxonomic dictionaries for thermophysical properties; the models for data presentation and their uncertainties; the inclusion along with the parameters of the state, some additional factors, such as the material porosity, the burnup rate, the irradiation rate and others; axiomatics of the properties applicable to the given class of materials.

Calculation of the transport properties of dilute gas mixtures on the basis of model potentials. Mercury–argon system

Interatomic potentials V(Hg–Hg), V(Ar–Ar), and V(Hg–Ar) of atoms in their ground electronic state are analyzed for the technically important mercury–argon dilute gas mixture. The collision integrals are calculated for these potentials, and the transport properties of mercury, argon, and their mixture, such as, viscosity, thermal conductivity, and self-diffusion and mutual diffusion coefficients of compounds, are determined using the molecular-kinetic theory relationships. Detailed tables of properties on five isotherms within a range of 300–2000 K and mixture concentrations of 0.001–0.999 are given. Tables of the properties also contain thermal diffusion factors and Prandtl (Pr) and Schmidt (Sc) numbers. Some specific features in the behavior of properties depending on the composition are considered.

Interaction potentials of nine quasi-spherical molecules in the database on the transport properties of gases

Experimental data on the second virial coefficient and viscosity are generalized using (m-6) Lennard-Jones potentials with four and three parameters for a group of rarefied gases consisting of quasi-spherical molecules with tetra- and octahedral symmetry. Analysis is made of correlations of the parameters of potentials with the structural characteristics of molecules and critical temperatures of substances. The parameters of three-parameter (m-6) Lennard—Jones potential for nine molecules of CH4, CF4, CCl4, C(CH3)4, SiCl4, Si(CH3) 4, SF6, MoF6, and WF6 are included in the EPIDIF information-and-computation database (epitaxy and diffusion processes) on the transport properties of rarefied gases and gas mixtures.