Symmetry Analysis of Equations for Convection

The differential equations describing convection in binary mixture with Soret and Dufour effects are considered. The symmetry classification of these equations with respect to the constant parameters is made. It is shown that a generator producing equivalence transformations of constants is defined accurately up to a factor arbitrarily depending on these constants. The equivalence group admitted by the governing equations is calculated. Using this group, a transformation connecting the systems with and without Soret and Dufour terms is derived. In pure Soret case, it reduces to a linear change of temperature and concentration. The presence of Dufour effect requires an additional change of thermal diffusivity and diffusion coefficient. A scheme for reducing an initial and boundary value problem for Soret–Dufour equations to a problem for the system without these effects is proposed

Production of nanoporous sorbents by partial steam-air conversion of charcoal

An effective sorbent is activated carbon having a developed nanoporous structure with an average pore diameter about 2-4 nm. Perspective method of activated carbon production is the partial steam conversion of the coal bed in boiler furnaces of power plants. The additional thermal energy is produced by burning the syngas. The aim of this work is to study the co-production of activated carbon and syngas by partial steam-air conversion of charcoal. Due to the presence of oxygen in the flow, intensification of conversion occurs. In the laboratory bed reactor, the mass loss curves and the syngas composition were obtained at temperatures of 800°C and 900°C. Two zones with different reaction mechanisms were identified on the height of the bed. The reactions between carbon and steam shift toward hydrogen formation in the oxygen zone. The dependence of the porous structure of the activated carbon on the conversion degree of the raw material is obtained. The maximum of micropores is formed at a conversion degree of 0.5. The material and energy balance of the partial conversion in the laboratory reactor was estimated. © 2018 Institute of Physics Publishing. All rights reserved.Russian Foundation for Basic Research (RFBR

Дозиметр ультрафиолетового излучения

Розглянуто проблему, пов'язану з впливом ультрафіолетового (УФ) випромінювання Сонця на організм людини. Описано особливості розробки і експлуатації вітчизняного портативного дозиметра УФ-випромінювання ФС-01.Considered problem connected with the impact of Sun ultraviolet (UV) radiating on the human organism. Described particularities of development and usages domestic portable sensor of UV-radiating ФС-01.Рассмотрена проблема, связанная с воздействием ультрафиолетового (УФ) излучения Солнца на организм человека. Описаны особенности разработки и эксплуатации отечественного портативного дозиметра УФ-излучения ФС-01

The thermal expansion and thermophysical properties of an aluminum and Al/B 4 C composite

The paper presents results of experimental studies of the thermal expansion and thermophysical properties of an Al/B 4 C composite with a boron carbide content of 20 wt% and technically pure aluminum in the temperature range from 100 to 600°C to evaluate the possible use of this composite as a neutron-protective material in the nuclear industry. © 2017 Author(s).We would like to appreciate the assistance of S. M. Zadvorkin, S. V. Lepikhin and L. S. Goruleva in conducting the investigations. Investigation was supported by Act 211 of the Government of the Russian Federation (agreement No. 02.A03.21.0006)

An Analytical Model for Calculation of the Steel Hardness after Continuous Cooling

A number of modern engineering steel grades were analyzed using the CCT diagrams plotted by means of the dilatometer. The statistical analysis of the experimental data allowed for the determination of the equations connecting the critical cooling rate to achieve fully martensitic microstructure and the martensite hardness with the chemical composition of the steel. The dependence of the steel hardness on the cooling rate in the range of 0.1...30 C/s was determined. It was shown that this dependence had the logarithmic character for every studied steel grade. The equations connecting the coefficients of the logarithmic function with the chemical composition of steel were obtained. © Published under licence by IOP Publishing Ltd.The work was supported by the Act 211 of Government of the Russian Federation, contract № 02.A03.21.0006, the Ministry of Science and Higher Education of the Russian Federation, project №11.1465.2014/K, and by the state assignment of the M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, theme “Laser”

Optimization of the thermodynamic and thermophysical properties of the gas turbine cycle working fluid

A gas turbine cycle working fluids group based on their production technology and application is presented. The energy parameters analysis procedure of unclosed and closed gas turbine cycles is described. The comparison of the effect of the working fluids thermophysical and thermodynamic properties variations on the useful work l0 of both unclosed and closed gas turbine cycles is presented. The effect of the fuel gas composition variation on the useful cycle work l0 is revealed. The effect of the working fluid thermophysical properties variation on the gas turbine cycle optimal combination of thermodynamic properties (T3 and P3 ) is presented. © Published under licence by IOP Publishing Ltd