Home – Home – Jornals – Thermophysics and Aeromechanics 2010 number 3

Presented below is the review of the results of experimental studies of energy characteristics of Darrieus rotor with vertical rotation axis. Influence of main geometry parameters of the rotor on its energy characteristics has been analyzed. It is shown that Darrieus rotor may have the higher level of energy characteristics than the best propeller wind turbines.

A novel approach was proposed to developing a combined algebraic-differential model of turbulent viscosity, which was then used to modify the traditional method for calculating turbulent boundary layers on bodies of revolution immersed in an incompressible flow. Ample experimental data were invoked to test the developed model through prediction of features inherent in turbulent boundary layers on the body of revolution in the presence of Large Eddy BreakUp (LEBU) devices installed in the vicinity of the streamlined surface. Within the developed approach, we showed it possible to calculate the evolution of local governing characteristics of turbulent flow in a broad range of LEBU parameters.

The PIV technique was used to measure the instantaneous vector fields of flow velocity and vorticity behind a thin cross-flow rib installed in a channel with laminar, transient, or turbulent flow. The data were treated statistically to determine the fields of mean longitudinal flow velocity and the correlations of pulsating velocity components 〈u′v′〉 and 〈u′u′〉. Some features of the flow structure developing under conditions of laminar-turbulent transition behind the rib have been revealed.

Viscous gas flow in the domain with a cubic package of spheres is considered. The problem formulation and the solution method are briefly presented. The integral parameters are presented, and the flow character is identified.

Results of experimental investigation of regular wave conditions for straight rivulets falling down a vertical plane are presented. Field measurements of the local thickness of rivulets were carried out with the help of laser-induced fluorescence. Data on the wave structure of rivulets is shown in a wide range of frequencies of regular waves for different Reynolds numbers of the flow and contact wetting angles. It was observed for all studied wave conditions that transverse width of rivulets and wetting angles are insensitive to the phase of propagating waves. Moreover, it was found that the wave structure of rivulets differs significantly for the cases of low and high values of the contact angle.

Heat transfer in the laminar-wavy film of liquid falling over the heated plate is studied numerically. To describe the wavy film flow the integral model is applied. Calculation results demonstrate the effect of physical properties of liquid and wavy flow parameters on heat transfer intensification by stationary running waves.

The process of rarefaction wave propagation in saturated vapor at sudden contact with cold liquid is studied.

The mathematical model of decomposition of a spherical gas hydrate particle in water behind a 1D wave of the stepped profile (rarefaction wave) is suggested. Contribution of the outer and inner heat flux in a particle to the process of hydrate decomposition is studied. The effect of the gas hydrate particle size, pressure and temperature jumps in liquid on gas hydrate decomposition is investigated.

A physical and mathematical model is developed, and numerical studies are carried out to investigate the processes of non-equilibrium crystallization of a metallic liquid droplet modified with refractory solid nano-inclusions at its impingement on a solid substrate. The conditions are considered, which are typical of thermal spraying of metal coatings, including the plasma spraying. An analysis of the splat formation depending on the concentration of refractory nanoparticles within the metallic droplet volume, their size and substrate temperature is given. The characteristics of splats computed using the non-equilibrium and equilibrium models of crystallization are compared under the same remaining conditions. The conditions of applicability of models are discussed.

Temperature dependences of the density of liquid silver-tin melts containing 61.6 and 96.5 wt. % Sn (59.3 and 96.15 at. % Sn) have been determined using gamma-ray attenuation technique over the temperature range from liquidus line to 950 K. The density changes during solid-liquid transition have been directly measured for the first time for eutectic alloy (96.5 wt. % Sn). The temperature and concentration dependences of the thermal properties for Ag-Sn system have been constructed. Kinetics of homogenization of the melts with mean composition of 61.6 wt. % Sn has been investigated in the temperature range from 770 to 950 K. The coefficients of binary diffusion have been derived from these experiments.

A wide variety of electric-arc reactors are involved in different areas of science and technologies. Therefore, a demand arose for their systematization. Here we present the classification of most existing types of electric-arc reactors regarding the mutual positioning of plasma-generation and reaction zones. There are three types of reactors: separated, single-chamber, and combined type. Different engineering solutions in each type led to some scatter in the thermal efficiency, power range, lifetime, and other results. No consideration has been given to the reactors of single-chamber heating. They are very special and require individual researches.

The modeling of the formation of the equilibrium arc discharge structure in the axisymmetric formulation was carried out in a wide range of the values of current and radius. The boundary separating the radiation and heat-conducting regimes of discharge combustion was determined from computed data. The influence of energy mechanisms on the structure of the discharge was analysed, and a channel model was proposed for computing its parameters in the radiation regime.

The equilibrium and kinetics of samarium ion sorption from the solutions of its sulphate and nitrate on natural mordenite-containing tufa are studied. It is established that samarium is extracted quantitatively from the diluted solutions. With an increase in solution concentration, a decrease in sorption capacity of tufa with respect to samarium ions is observed. The kinetic parameters of sorption process are determined.

The possibility of phosphogypsum processing into sodium sulphate and technical-grade calcium carbonate using soda is considered. It is shown that the conversion of phosphogypsum proceeds within 20-30 min by 96-98 %. To obtain sodium sulphate solutions with low concentration of calcium sulphate, it is necessary to carry out conversion under the conditions of a 5-10 % excess of soda over sulphate ions with respect to the stoichiometrically necessary amount. It is established that in this case sodium sulphate corresponds to the high-grade product. The second product of phosphogypsum processing - technical-grade calcium carbonate - is promising for use as filler in the production of linoleum; after further processing it is a raw material for obtaining the salts of calcium, strontium and rare earth elements.

On the basis of the opal-cristobalite rock, a sorbent for the cations of heavy metals from an aqueous medium was prepared. An increase in the sorption capacity of the rock was achieved by means of thermal and chemical modification, as well as by immobilization with γ-aminopropyltriethoxysilane. The optimal conditions for the elevation of the sorption activity of the rock were determined. Sorption of Cu²⁺, Ni²⁺, Zn²⁺ cations on the prepared samples was carried out; the sorption capacity for these ions was determined. The kinetics of sorption of metal cations from aqueous solutions on the modified rock was studied, along with the dependence of the sorption of Cu²⁺, Ni²⁺, Zn²⁺ cations on solution pH and on the concentration of the background electrolyte.

For the purpose of utilization of the side products formed in the processes of production of caprolactam, adipinic acid etc. at the stage of liquid-phase oxidation of cyclohexane with atmospheric oxygen, the possibility to oxidize the compounds incorporated into the light-coloured fraction of X-oil - α,β- and β,γ-unsaturated bicyclic ketones - was investigated. Oxidation was carried out using a 30 % hdyrogen peroxide solution at a temperature of 55-65 ^oC at atmospheric pressure in a two-phase system (aqueous phase - organic phase) in the presence of homogenous bifunctional nanostructurized catalysts based on tetra(oxodiperoxotungsteno)phosphate in combination with quaternary ammonium cations. The analysis of reaction products was carried out by means of GC-MS, TLC and GC.

The concentrations of metals (Fe, Mn, Cu, Zn, Cd, Co, Cr, Ni) in liver, kidneys and muscles of Baikalian seals Phoca (Pusa) Sibirica gmel captured in Autumn 2002-2003 in the Chivyrkuy Bay and in Spring 2004 near the Proval Bay of Lake Baikal were investigated. The data obtained were processed with the help of multivariant procedure for main components. It was established that the degree of pollution of the lake area with heavy metals is low; their level in the ecosystem is comparable with the background one characteristic of non-polluted regions of the oceans.

The effect of ozonation in chloroform on the changes of the chemical composition of solid fossil fuel of different genetic types and petrographic composition of the brown-coal maturity stage was investigated. It was established that the character of ozonolytic transformations of the organic matter, yield and component composition of the products of coal ozonation are determined by the features of the structural arrangement of coal. It was shown that the organic matter of solid fossil fuel may be transformed by more than 90 % into soluble products by means of liquid-phase ozonation in chloroform. The highest reactivity with respect to ozone is exhibited by the organic matter of sapromixite coal. With a decrease in the atomic ratio H/C in coal, the fraction of dicarboxylic aromatic acids in the water-soluble products of ozonation increases.

The effect of the nature and amount of the chiral modifying agent deposited on Csβ zeolite on the products ratio and on the enantioface differentiation of the reaction of 5,5,8-trimethylnona-3,7-diene-2-one with malononitrile is studied. The synthesized catalysts allowed for the first time to obtain optically active 1-hydroxy-2-imino-4-methyl-6-(1,1,4-trimethylpent-3-enyl)-cyclohex-3-ene-1,3-dinitrile.

The features of the application of porous materials impregnated with chemical reagents to obtain highly active sorbents are considered. The processes of iodine sorption and desorption from an aqueous solution with the carbon material of Tekhnosorb grade are studied. It is shown that this chemisorbent is efficient in absorbing mercury from its aqueous solutions with high concentrations.

The effect of the salt composition obtained from the wastes of soda production on the processes of hydration of mineral binders and solidification of plugging solutions was investigated. The developed formulas of plugging compositions based on the salt composition are reported.

Nanocomposites of the nonsteroidal anti-inflammatory preparation piroxicam with the oxides of aluminium, magnesium and silicon were obtained suing mechanical treatment in activator mills. Except for the composites of piroxicam with aluminium oxide, the solubility of piroxicam in all the obtained nanocomposites exceeded the solubility of the initial preparation. The changes observed in the IR spectra of mechanically treated mixtures provide evidence of the interaction of piroxicam with the oxides. The interaction of the pharmaceutical substance with the surface of oxides at the interface ensures stabilization of the drug in the metastable state thus preventing its crystallization and transformation from the zwitterion state into the neutral state.

Results of the investigation of acidic properties of glass fibre materials by means of IR spectroscopy of adsorbed ammonia and deuterium-hydrogen exchange on the basis of isopropanol dehydration rate are presented. It is shown that these catalysts contain a substantial amount of Bronsted acid centres (BAC) compared in force with the BAC of HZSM-5 zeolite. The concentration of BAC is proportional to the concentration of Al in the glass fibre. It was discovered that BAC are localized in the glass fibre volume. It was shown that the centres located at a depth up to 100 nm are available for isopropanol molecules.

The use of chlorination in water preparation system as the main method of disinfection often causes secondary pollution of drinking water with volatile organic halogenated compounds; chloroform is the major one of them. In the present work, the results of the investigation of the efficiency of sorption extraction of chloroform from aqueous solutions with the sorbents of different nature are reported. The degree of chloroform extraction for its different concentrations in aqueous solutions, and limiting sorption values are presented. The most efficient regeneration method was chosen on the basis of the data obtained in the multi-aspect investigation.

Alternative methods of the synthesis of pyrimidine-containing diamines are considered. These compounds are initial monomers for obtaining thermally stable high-module polymers (polyimides) which are used to develop promising materials for new technics. In accordance with the structure of diamines, the methods of their synthesis are systematized, their reactivity is evaluated. The problems concerning technological reasonableness, availability of the initial raw material and the possibility of scaling at separate stages of synthesis are assessed. The data on the thermal stability and deformation strength characteristics of pyrimidine-containing polyimides which are promising for the development of materials functioning within a broad range of extremal thermal conditions in a number of the areas of modern technologies are reported.

Thermal co-processing of hydrolytic lignin and heavy black oil within temperature range 350-415 °С at atmospheric pressure is investigated. The major products are represented by the liquid distillate products released from the reactor, and by the cracking residue in the reactor. Addition of lignin causes a substantial acceleration of the reactions of liquid-phase thermal cracking of black oil and increases the yield of distillate products. The ways of practical application of these products are proposed on the basis of the obtained data on the composition of the products of thermal co-processing of lignin and black oil.

Synthesis of microspheric zeolite sorbents based on the vitrocrystalline cenospheres of power engineering ashes was carried out for the first time, without any crystallization nuclei or structure-forming components. As a result of hydrothermal processing, the aluminosilicate material of cenosphere wall is transformed into low-module zeolites with the conservation of the morphology of initial particles. The final products are hollow spheres with a size of 80-200 m; their walls are composed fully or partially of the crystals of NaA, NaX and NaP1 zeolites.

Aerodynamic method followed by sieve analysis of the resulting fractions was applied to separate the concentrates of cenospheres of volatile ash from the combustion of coal of the Kuznetsk Basin at the Moscow Heat and Electric Power Plant (HEPP) No. 22, Belovo Hydroelectric Regional Power Plant, and some fractions of the concentrate of cenospheres obtained at the Novosibirsk Heat and Electric Power Plant No. 5. From the concentrate of the Moscow HEPP, 90 fractions with different particle sizes (70-250 m) and apparent (0.16-0.52 g/cm³) were separated. Independently of particle size, the apparent density of the fractions with the maximal yield is 0.33-0.35 g/cm³, while the ratio of the apparent wall thickness to the particle diameter is 0.042-0.043. The process of the aerodynamic separation of cenospheres of the concentrates from different sources is satisfactorily described by the theoretical dependencies for the escape of spherical particles; the deviations are first of all due to the non-spherical shape of cenospheres.

Under laboratory conditions, we determined the geochemical characteristics of the frozen soil of Yakutia, the activity of soil enzymes, physiological and biochemical characteristics of hornwort dandelion and relative stability of the genome of plant cells to the action of oil toxicants after the introduction of oil (0.07-1.95 vol. %) into soil samples. It is shown that the permissible level of pollution with oil for which soil is able to get recovered is ~1 g/kg of soil.

Results of the examination of the seeds of legumes growing under the conditions of moderate latitudes for the presence of reserve water-soluble polysaccharides galactomannanes are presented. A quantitative estimation of galactomannane content in the seeds of 45 species of 13 genera 7 tribes of the legume family is presented. For 23 species, a chemical characteristic was determined which shows the ratio of mannose to galactose monomers in galactomannane molecule. The results obtained in the investigation can be used for the search of home sources of plant hydrocolloids which would be of interest for various areas of science and technology.

It is shown that the main hindrance for the use of phosphohemihydrate, obtained during sulphuric treatment of the Khibiny apatite concentrate, in the production of construction materials is an increased content of phosphorus admixture in water-insoluble form. According to the previously developed technology of sulphuric extraction of the concentrate of lanthanoids from phosphohemihydrate, one achieves efficient leaching of water-insoluble phosphorus which gets accumulated in leaching solutions during their repeated use. It is proposed to remove phosphorus from sulphuric solutions in the form of hydrated titanylphosphate by means of precipitation with titanyl sulphate. The possibility to recover titanyl sulphate with the help of the alkaline treatment of hydrated titanylphosphate is demonstrated; the resulting product is a component of detergent Na₃PO₄ · 12H₂O. The versions of the sulphuric technology of phosphohemihydrate treatment excluding the formation of liquid wastes that require utilization are considered.

Synthesis of the hydrophilic derivatives of Осуществлен синтез гидрофильных производных 3-(4-hydroxyaryl)propyl series with sulphur-containing ionogenic fragments was carried out. The regularities of the changes of toxic effect of the synthesized compounds depending on their structure were investigated with respect to laboratory animals (mice) and bacterial cultures (Photobacterium phosphoreum).

For wastewater of the Angarst Electrolysis Chemical Plant as an example, the galvanochemical purification of the liquid radioactive wastes from the sulphuric scheme of uranium refining is investigated; its main regularities and features are determined.

We optimised the method of obtaining the monoammonium salt of glycyrrhizic acid (glycyram) from the roots of the Ural licorice ( Fisher) of Siberian populations. The method includes the following stages: extraction of the roots with a 0.5 % solution of NH₄OH, precipitation of the sum of acids with the help of concentrated H₂SO₄, subsequent re-extraction with a 1 % solution of H₂SO₄ in acetone, salting out the triammonium salt of glyccyrrhizic acid using a 25 % NH₄OH solution, transformation of this salt into the monoammonium salt (glycyram) by crystallization from glacial NH₄OH. Using this method, one may obtain the samples of glycyram with a purity of 85.2-87.5 % (according to the HPLC data). The glycyrrhizic acid content in the investigated samples of licorice roots is 2-4 %.

A resource-saving and ecologically safe technology of the purification of waste water of galvanic works from heavy metal ions is developed on the basis of the results of the experimental investigation of the equilibrium, kinetics and dynamics of adsorption, and mathematical modelling. A schematic diagram of the set-up for the purification of the wastewater from the galvanic works is proposed.

Using model solutions, we determined the conditions for the purification of wastewater containing fluorine in the concentration of 10 mg/in the form of complex anions AlF and/or FeF. Purification is performed with the help of cerium compounds. For real waste water of the plants situated in the Kola region (Apatit JSC, Lovozero GOK JSC), optimal modes of purification from fluorine impurity, using titanium compounds, down to the standard values of fluorine and sulphate ion concentrates established for drinking water were developed.

The effect of the preliminary chemical treatment on the process of mechanical powdering of the raw material is investigated. It is shown that the treatment of sawdust with the solutions of an acid, an alkaline or with enzymatic preparations results in the chemical modification of one of the components of the lignocarbohydrate matrix of sawdust (cellulose, hemicelluloses or lignins) and in the changes of the structure of wood. The effect of enzymatic hydrolysis on conversion degree and efficiency of powdering is investigated. It is shown that even a small degree of carbohydrate conversion (1-2 %) is sufficient for a decrease in the strength of wood structure by means of the enzymatic destruction of carbohydrates. The fraction of particles with a size within the range 19-25 Ојm increases approximately by a factor of 10 with the help of the method of preliminary chemical treatment of sawdust.

For the analysis of the samples of biological tissues (human myocardium and blood vessels) obtained by biopsy, the necessity arises to study the effect of the radiator density variations on the determination of chemical elements, since sample thickness varies depending on the type of tissue under investigation and sample mass (during sample preparation). Because of this, with the Bovine liver NIST 1577 standard sample, we studied the effect of the surface density of radiating device on the coefficients of relative sensitivity. The experiments were carried out at the station of elemental X-ray fluorescence analysis on the basis of the Siberian Centre for Synchrotron Radiation (Institute of Nuclear Physics, SB RAS, Novosibirsk). It was established that a change of the density of reference tablet density (at the excitation energy of 17 keV) during normalization of peak areas of the elements under determination to the area of Compton's peak has almost no effect on the results of analysis for the elements from Mn to Zn. For K, Ca, Fe and Rb, substantial differences of the coefficients of relative sensitivity (R_ist) are observed while the radiator density varies from 14.9 to 45.8 mg/cm².

Flavonoid content in the samples of plants of 15 species of Myosotis genus is examined. It is established that it is mainly 1.0-4.0 % in the plants of the investigated species; it is characterized by high variability for the samples collected in different regions. The variability of flavonoid content within the limits of one coenopopulation is low or medium. The species of Alpestres the section Myosotis of genus, especially M. asiatica , contain a large amount of flavonoids (up to 7.4 %) and are of interest for further investigation. The plants collected during the flowering period may be used as the sources of flavonoids.

In order to realize the strategy of the world community in the area of education for sustainable development, the D. I. Mendeleev Russian Chemical and Technological University and non-profit organization Love Russia  (Great Britain) for school pupils. In 2004-2007, practical ecological monitoring involved the pupils of more than 50 schools, boarding schools and social rehabilitation centres for juveniles; they carried out monitoring of water in the Kasimovo, Shilovo, Spassk Districts of the Ryazan Region and examined more than 150 objects along the passage 200 km wide along the Oka river. The results obtained in the investigation were considered as a part of ecological audit and discussed from the viewpoint of a practical example of the social responsibility of human beings for the processes that take part in the biosphere. A positive experience of the studies aimed at research of the problems of sustainable development and at carrying out ecological monitoring of wild nature allow us to propose these courses as a compulsory regional component of the school teaching process.