Volume 97, №2

REALIZABLE-LOAD RANGE OF THE RECTIFICATION OF A MULTICOMPONENT MIXTURE

The problem on the optimum organization of the rectifi cation of a multicomponent mixture in a rectifying column was considered. It is shown that, in the case where heat is supplied to the boiler of the column and is removed from its dephlegmator, the boundary of the realizable-load range of the column represents a parabola convex upwards with two characteristic parameters. The interrelation between the indicated characteristic parameters and the kinetics of the heat- and mass-transfer processes in the column, the composition of the mixture separated in it, and the mixture separation boundary selected was determined. The consequences of the possibility of parametrization of the boundary of the realizable-load range of a rectifying column are discussed. A rule for the choice of the boundary of separating a multicomponent mixture has been formulated.

Author:  A. M. Tsirlin A. I. Balunov
Keywords:  rectifi cation, multicomponent mixture, separation order, irreversibility, realizable regimes, maximum output
Page:  259

DIAGNOSTICS OF MATHEMATICAL MODELS OF THERMOELASTICITY. PART 1. WEAK SOLUTIONS OF BOUNDARY-VALUE PROBLEMS AND FORMULATION OF THE PROBLEMS OF DIAGNOSTICS

The formulations and methods of solution of the problems of diagnostics of thermoelasticity on a stationary boundary of a solid body are considered. A weak formulation of the boundary-value problem is presented for a nonlinear hyperbolic equation (a nonstationary wave equation with density, elasticity modulus, and thermal stress depending on temperature) with mixed boundary conditions. An approximate solution of this problem in the space (1) W₂ has been obtained, and an example of solution is given. Based on the weak formulation of the boundary-value problem, problems of diagnostics have been formulated in the sense of the theory of function traces. According to the theorem about the uniqueness of the relationship between the function and its trace in the space (1) W₂ , a conclusion has been drawn about the need to control the convergence of the calculated wave function to the experimental one only on boundaries with unstable conditions in solving the problem of diagnostics.
Author:  A. G. Vikulov
Keywords:  boundary-value problems, inverse problems, weak solutions, trace of a function, diagnostics, thermoelasticity
Page:  267

MODELING THE SOCIAL FORCE DYNAMICS OF A GROUP OF INDIVIDUALS IN A ROOM WITH OBSTACLES

A model of collective behavior of group members in a room with internal obstacles is presented. Social behavior is described in terms of the eff ective potential that prevents a close physical contact between individuals and between an individual and the boundary of the room. The dynamics of all members of the group is a solution to a system of stochastic ordinary diff erential equations, for the numerical integration of which modern modifi ed Runge–Kuttatype algorithms are used. Depending on the situation, the speed of movement of individuals consists of a determinate component directed toward the exit and a chaotic component modeled by a random process structured in time (colored noise). Cases of calm wandering of individuals in a gallery with columns and purposeful movement in the case of panic are considered. The infl uence of social dynamics on the likelihood of susceptible individuals becoming infected in the presence of infected group members is discussed. A formula has been obtained for calculating the infl uence of the numerical concentration of individuals on the averaged speed of group drift. The calculation results are compared with empirical data borrowed from the literature.
Author:  I. V. Derevich A. A. Panova
Keywords:  social force model, drift speed, random process, stochastic ordinary diff erential equation, autocorrelation function
Page:  277

CHEMICAL ANALYSIS OF THE COMPOSITION OF GAS-PHASE AND LIQUID PRODUCTS OF GASIFICATION OF LOW-CALORIE SOLID-PHASE BIOFUEL MIXTURES IN A SUPERADIABATIC REACTOR

The authors have given results of experimental investigations into the gasifi cation of a solid composite fuel in a superadiabatic reactor with a water-cooled condenser making it possible to collect and analyze gas-phase and liquid gasifi cation products. A detailed study has been made of the processes of gasifi cation of low-calorie solid-fuel mixtures based on wood chips with a high content of water (as high as 37.1%). In the experiments, full, in practice, conversion of the solid fuel into gaseous and liquid-phase products was observed. An analysis of the gas-phase gasifi cation products and nitrogen oxides was made using electrochemical gas analyzers. The composition of the liquid-phase products was analyzed by the mass-spectrometry method and the high content of organic substances (phenols, organic acids, and ethers) in them was shown. The obtained data confi rm the promising nature of gasifi - cation of low-calorie solid-fuel mixtures in a superadiabatic regime as an energy-saving and environmentally safe method to recycle and utilize wood waste, and also components of municipal solid waste.
Author:  N. M. Gorbachev, S. I. Futko, A. V. Vlasov, M. I. Rusakevich, I. A. Koznacheev, T. N. Bochko, and É. K. Buchilko
Keywords:  biomass, wood, municipal solid waste, gasifi cation, pyrolysis, gas fi ltration, superadiabatic regime, gas analysis, mass spectrometry
Page:  287

NUMERICAL CALCULATION OF IGNITION OF WOODEN STRUCTURES BY HEATED PARTICLES

A mathematical model of the ignition of wooden structures by "hot" particles is proposed. The spatial problem is considered in a three-dimensional formulation in Cartesian coordinates. It was found that the ignition of wood is determined by the processes of drying, pyrolysis of the dry reagent, and by the reactions of oxidation of carbon monoxide, methane, and hydrogen. The dependences of the wood ignition delay time on the initial temperature of the "heated" particles and their quantity were found. In some cases, a qualitative comparison of the calculation results with the known data was noted.
Author:  E. L. Loboda, D. P. Kasymov, and A. S. Yakimov
Keywords:  wood, heated particles, conjugate heat exchange, ignition
Page:  295

DESCRIPTION OF HEAT TRANSFER IN TUBE BUNDLE-CONTAINING HEAT EXCHANGERS BASED ON THE ANALOGY WITH A HEAT-RELEASING GRANULAR BED

Based on the analogy of a tubular heat exchanger with a structured heat-releasing granular bed, a technique has been developed that makes it possible to unify the simulation of heat transfer in heat exchangers with a tube bundle of diff erent types and designs.
Author:  Yu. S. Teplitskii, E. A. Pitsukha, and A. R. Roslik
Keywords:  granular bed, heat exchanger, tube bundle, analogy, structured bed
Page:  305

PHYSICOCHEMICAL MECHANICS OF MICROSTRUCTURAL TRANSFORMATIONS OF SWELLING CLAY MINERALS

An original model of microstructural transformations during swelling of clays is considered, and a thermodynamic and physical-mechanical description of the specifi c features of clays in the process of swelling in vapors and aqueous solutions is given. The model proposed to explain these properties is based on the idea of mutual movement of clay particles in clay rock aggregates during swelling with the formation of new pores between clay particles forming crystallites and aggregates. The model is based on a mechanism of utilizing excess surface energy of clay particles with account for the infl uence of certain parameters of the medium, for example, solution concentration, through a change in the mutual orientation of clay particles, mainly due to rotations or shifts relative to each other with the formation of a free surface available for further wetting. In a thermodynamic description, such a process will manifest itself in a change in the energy of surface interaction on the wetted areas of particles when moving during mutual shifts and rotations. Changing in this case is also one of the most important parameters of the clay rock — microporosity. In this work, this phenomenon was studied experimentally using the methods of static moisture capacity and Mössbauer (gamma-resonance) spectroscopy. The proposed model makes it possible to explain the features of the clay swelling process and compare the observed experimental data with the theoretical description of the clay swelling process.
Author:  M. G. Khramchenkov, F. A. Trofi mova, R. É. Dolgopolov
Keywords:  clay rocks, crystallites and aggregates, microporosity, clay swelling, low permeability
Page:  315

ON THE EFFECTS OF SPATIAL INHOMOGENEITIES OF BUOYANCY ON THE DYNAMICS OF A ROTATING MEDIUM

There are indications that spatially inhomogeneous buoyancy forces can play a signifi cant role in the dynamics of intense tornado-type atmospheric vortices. The paper considers a linearized model of disturbances caused by buoyancy deviations (in particular, inhomogeneously distributed heavy impurity) in an intense vortex with a vertical axis. Analytical relations allowing assessment of the amplitude of perturbations of velocity and pressure have been obtained.
Author:  L. Kh. Ingel′
Keywords:  vortex motion, buoyancy, spatial inhomogeneities, diff usion, perturbations, linear model, analytical solution
Page:  325

PROPAGATION OF THE EXHAUST GASES FROM A CAR AND TURBULENT DIFFUSION IN THE AIR OVER A ROAD

It is shown that the scattering of the exhaust gases from a car is mainly due to their vertical turbulent diff usion with a coeffi cient increasing with increase in the velocity of the wind over the car or in the velocity of movement of the car. Results of numerical solution of the equation for the convective diff usion of the exhaust gases from a single car are presented. Qualitative estimates of the propagation of the exhaust gases from a convoy of cars have been made
Author:  S. P. Fisenko
Keywords:  turbulent diff usion, wind velocity, height of a car, Galerkin method
Page:  330

PROTECTIVE FILM ON THE PLATE SURFACE IN COOLING FLOW THROUGH AN INCLINED SLOTTED CHANNEL UNDER THE INFLUENCE OF A HARMONICALLY CHANGING PRESSURE

The results of numerical modeling of convective fi lm cooling of a plate in the vicinity of an inclined slotted channel with high-temperature and cooling fl ows past its two sides are presented. A fl at inclined slotted channel connects the areas of high-temperature and cooling gas fl ows. The movement of gas in both the high-temperature and cooling channels occurs under the infl uence of pressure diff erences in the inlet and outlet sections. In this case, along with the stationary component, the pressure in the cooling channel contains a component that varies according to a harmonic law. Calculations of thermal and velocity fi elds on both sides of the plate were performed, and the parameters of the cooling fi lm were described at various frequencies of pressure oscillations in the region of the cooling fl ow
Author:  A. L. Tukmakov, A. A. Akhunov, N. A. Tukmakova and V. V. Khar′kov
Keywords:  numerical modeling, Navier–Stokes equations, McCormack scheme, multiply connected regions, wall functions, convective-fi lm cooling
Page:  336

INSTABILITY OF THE BOW SHOCK WAVE AND FLOW DUE TO THE CURVATURE OF THE FLOW OF A CHEMICALLY REACTIVE GAS

The authors have presented experimental data and theoretical investigations of turbulence induced by the chemical processes in the compression zone ahead of the blunt body fl ying in a multiatomic gas medium. The possibility of the fl ow instability just due to the physicochemical processes in the gas and to the fl ow curvature irrespective of the boundary conditions on the body′s surface has been substantiated theoretically. Conditions for the fl ow instability have been found analytically. The found conditions for the occurrence of instability are in good agreement with experimental investigations not only quantitatively, but also qualitatively.
Author:  A. S. Baryshnikov, P. A. Popov, and A. B. Gerasimenko
Keywords:  fl ow past bodies, physicochemical processes, fl ow instability, dissipation
Page:  345

ACOUSTIC PROBING OF UNDERWATER EJECTIONS

A numerical study was carried out to investigate interaction of a pressure wave of fi nite length with a gas–liquid zone, which is a cut of a submerged jet of a mixture of water and oil with methane bubbles in a channel. The possibility of determining the degree of jet opening and the volumetric contents of oil and gas in it from pressure waves refl ected from the boundaries of the jet is considered.
Author:  I. K. Gimaltdinov, M. V. Stolpovskii, and E. Yu. Kochanova
Keywords:  pressure wave, gas–liquid zone, mixture of oil and water
Page:  353

IMPACT OF SAND PRODUCTION ON THE HYDRODYNAMICS OF A LIQUID IN A RESERVOIR–PIPELINE SYSTEM

A model has been constructed for unsteady motion of a liquid in a reservoir–pipeline system with account for sand production, and boundary value problems have been solved. The eff ects of wall permeability in pipes and sand deposition in them on the dynamics of the pressure fi eld in the pipe and in the reservoir and on the reservoir productivity have been determined. Numerical calculations have been performed at practical values of the system parameters.
Author:  É. M. Abbasov and N. A. Agaeva
Keywords:  sand production, motion of a liquid, diff erential equation, continuity condition, Laplace transform
Page:  361

HEAT EXCHANGE OF AN ELECTRICALLY CONDUCTING LIQUID IN A SPHERICAL INTERLAYER

The results of numerical modeling of unsteady heat exchange and magnetic hydrodynamics of an electrically conducting liquid in a spherical interlayer with regard to the Joule heat dissipation are presented. The infl uence of the magnetic Reynolds number and homochronicity number on heat exchange evolution and magnetic hydrodynamics of liquid was investigated.
Author:  S. V. Solov′yov
Keywords:  mathematical modeling, unsteady heat exchange, magnetic hydrodynamics, Joule heat dissipation, spherical layer
Page:  375

STUDY OF LEAKAGE AND EXPLOSION HAZARD CHARACTERISTICS OF A COMPRESSED NATURAL GAS AT A GAS STATION

This paper presents the results for a model of a typical urban compressed natural gas (CNG) station obtained with the help of numerical methods on the assumption that the leakage explosion scenarios run under three orifi ce sizes. The simulation demonstrates that the CNG leak rate is quite high and the leaking gas cloud spreads quickly along the ground, increasing the vertical diff usion speed. As a result, longitudinal space becomes the main area of hazard. The hazard explosion overpressure is concentrated mainly in the narrow area between the tank and surrounding buildings, and the maximum explosion overpressure exceeds 0.4 bar. The range of the overpressure hazard will cover the entire gas station where a shock wave, high temperature, and fl ame damage may occur, but projectile strikes may exceed this range, and the risk of explosion becomes higher. In addition, the attenuation of the overpressure by the wall is signifi cant, and the maximum attenuation rate can reach 65%.
Author:  W. Li, X. Shen, Z. Huang, T. Mao, Q. Hu, and C. Ma
Keywords:  compressed natural gas, fi lling station, leakage, vapor cloud explosion, hazard
Page:  387

MODELING OF HEAT AND MASS TRANSFER IN THERMOPROTECTIVE COMPOSITE MATERIALS UNDER CONDITIONS OF PHASE TRANSFORMATIONS AT HIGH TEMPERATURES

A comprehensive physical and mathematical model is proposed, as well as a method of analytical solution for the processes of heat and mass transfer in thermoprotective composite materials during phase transformations of composite material binders with the formation of pyrolysis gases and a porous coke residue, through which gases are fi ltered to the outer boundary and blown into the high-temperature boundary layer. Mathematical simulation is carried out on the basis of the identifi ed law of decomposition of composite material binders without using models of the hard to formalize chemical kinetics and therefore suitable for most thermoprotective composite materials. The comprehensive physical and mathematical modeling includes the formation of a pyrolysis zone, the speeds of its motion inside the composite material, determining the density of composite material and pyrolysis gases in the pyrolysis zone, the density and stagnation pressure of gases in this zone, their nonisothermal fi ltration through the porous residue with injection into the boundary layer, as well as heat transfer in the presence of nonstationarily moving boundaries of phase transformations. Based on the relations of the proposed model, calculations were carried out, and their results were analyzed.
Author:  V. F. Formalev, B. A. Garibyan, and S. A. Kolesnik
Keywords:  heat and mass transfer, thermoprotective composite material, pyrolysis, pyrolysis gas, speed of movement of pyrolysis zone, nonisothermal fi ltration, porous coke residue
Page:  397

STABILITY CRITERION OF A ROTATING FLUID FILM IN THE POST-DRYOUT REGION OF SWIRLING FLOW BOILING

The paper considers the fragmentation of fl uid fi lms and, in particular, the used similarity numbers that characterize the process of fragmentation. Based on the analysis of a previously proposed mathematical model for a rotating fl uid fi lm evaporating in the Leidenfrost regime, the Sf criterion is proposed. It represents the relationship between the pressing inertial mass force acting on the fl uid fi lm and the dynamic eff ect of vapor from the heating wall.
Author:  S. É. Tarasevich
Keywords:  fi lm, post-dryout regime, twisting, stability, criterion, fragmentation
Page:  406

DIRECTIONAL WETTING OF PACKINGS WITH FORMATION OF ICICLES ON DISCRETE SUPPLY OF WATER IN THE FORM OF JETS UNDER CONDITIONS CLOSE TO A MINIMUM DENSITY OF WETTING AND DESALINATION OF WATER BY FREEZING

The article presents the results of studies of directional wetting of linear packings with formation of icicles on discrete supply of water in jets under conditions close to the minimum wetting density. It is proposed to use a Π-shaped linear distribution device. Water is cooled in a moving jet over the distribution device and drops falling on packings from the vertical surfaces of the distribution device, which is poorly wetted with water so that the drops fall mainly at the center of the spot where the jet is incident. To increase the uniformity and quality of wetting, it is proposed to use the ribs of the distribution device with thin fl exible elements. The best results are obtained when using cotton thread No. 40 located in two parallel turns in one rib with a pitch of 10 mm. In this case, the number of droplet formation centers at a water fl ow rate of 0.5 mL/s reached 70, while with 6 parallel turns in one rib the number of droplet formation centers was 35, and 7 when the surface had no ribs. The wetting device was tested in the course of wetting the tubes with production of icicles, which confi rms the improvement of wetting packings with water. Desalination of water by freezing in icicles has also been studied, with the highest salinity occurring at the bottom of the icicles. It was revealed that it is impossible to obtain drinking water with one freezing cycle.
Author:  I. I. Pukhovoi and A. L. Petrechuk
Keywords:  discrete water supply, minimum wetting density, icicled packings, desalination by freezing in icicles, distribution device, droplet formation centers
Page:  410

INVESTIGATION INTO POROSITY INDICES OF NANOFIBER-REINFORCED CONCRETE

A literature review has been carried out on the eff ects of carbon nanotubes (CNT) and macrolevel fi ber on concrete porosity indices. The results are presented of investigations into the porosity of nanomodifi ed concrete with dispersed reinforcement (nanofi ber reinforced concrete) in terms of the kinetics of water absorption of nanotubes and hard fi ber. For dispersed reinforcement, use was made of various hard fi bers and their combinations: polymer, basalt, steel wire ones and those from wave-, anchor-, and straight profi le sheets. It has been established that the introduction of dispersed fi bers results in a change of concrete porosity indices. Hard fi bers break up relatively large capillary pores into smaller ones. In this case, the fi ber coarseness and its amount in a volume are important. In integrated fi ber reinforcement, the size of capillary pores either decreases or does not change at all with respect to the initial concrete. Intense mechanical mix agitation contributes to raising the porosity index. Hard fi bers of a more rigid structure tend to demonstrate a higher propeller eff ect in mixing. The presence of diff erent-scale hard fi bers makes it possible to avoid a propeller eff ect and the need to increase the concrete porosity index.
Author:  S. A. Zhdanok, S. N. Leonovich, E. A. Sadovskaya
Keywords:  nanofi ber-reinforced concrete, porosity, nanocarbon tubes, hard fi ber, dispersed reinforcement, concrete
Page:  417

ANALYSIS OF THE KINETIC CHARACTERISTICS OF ELECTROCHEMICAL NANOFILTRATION SEPARATION OF ZINC-CONTAINING SOLUTIONS ON THE BASIS OF THE ELECTROCONVECTIVE THEORY

A method is proposed for optimizing the specifi c fl ow of a substance at the outlet of fi ltration membranes with limitations on current, electroosmotic permeability, retention coeffi cient, and current effi ciency at a constant transmembrane pressure. Based on analytical and empirical studies, engineering formulas have been obtained making it possible to calculate the specifi c output fl ow for fl at-chamber devices with OFAM-K and OPMN-P nanofi ltration membranes, which determines the productivity of the electrochemical nanofi ltration process of separation of zinc-containing solutions in wide ranges of changes in the electric current density, electrical permeability, and membrane retention coeffi cient, as well as in transmembrane pressure. The adequacy of the proposed method was verifi ed by comparing calculated and experimental data on the specifi c fl ow of matter at the output of the OFAM-K anode membrane and the OPMN-P cathode one. The verifi cation has shown the eff ectiveness of the obtained engineering formulas in a wide range of changes in the current density on the membranes
Author:  D. N. Konovalov, S. I. Lazarev, and K. K. Polyanskii
Keywords:  specifi c output fl ow, electrochemical nanofi ltration process, membrane, retention coeffi cient, zinc, electroconvection
Page:  424

AUGMENTATION OF HEAT TRANSFER BY USING INTERNAL RIB GEOMETRIES IN THE PRESENCE OF NANOFLUIDS: A REVIEW

In the last few years, the eff orts to increase the heat transfer rates have been concentrated on passive techniques in accordance with the aim of reducing the consumption of power and the establishment of more sustainable systems. One of these promising techniques is adding extended geometries (ribs) which serve as thermal conducting geometries and fl ow turbulators. Another technique is to add nanoparticles to enhance the overall thermal properties of working fl uids. Researchers had investigated this approach from multiple diff erent scientifi c points of view. Among these factors is the channel geometry, whether it is with a regular section or a microchannel. Two major types of channels can be noted: common or traditional channels with a macroscopic cross section and microchannels with much smaller sections. The investigation of a fl ow in a regular channel section includes the cases of laminar fl ow, turbulent fl ow, constant heat fl ux, constant temperature, as well as diff erent working fl uids. The current review tends to summarize the most remarkable eff orts which had been done in the last few years according to the above-mentioned aspects.
Author:  Haneen M. Al-Ali, Naseer H. Hamza
Keywords:  heat transfer, forced convection, enhancement, ribs, extended geometries
Page:  430

CHARACTERISTICS OF HEAT TRANSFER IN MHD FLOW OF LIQUID METAL IN A TUBE-IN-CHANNEL HEAT-EXCHANGE SYSTEM

The authors have conducted experimental investigations of heat transfer in upward fl ow of liquid metal in a vertical
tube passing along the axis of a square heated channel incorporated in the contour of a natural-circulation loop.
The measurements were carried out in the absence and in the presence of a transverse magnetic fi eld. Use was made
of probing measurement procedures with longitudinal microthermocouple probes in both the tube and the channel.
Consideration has been given to three basic regimes of cooling in upward fl ow of mercury in the tube and its natural
convective fl ow in the interchannel gap when the loop is shut off and when the loop is open without cooling and with
cooling. For the cases of uniform heating of the channel in regimes with variable Reynolds and Hartmann numbers,
the authors obtained the profi les of averaged temperature, the distributions of local heat-transfer coeffi cients, and
the pulsation characteristics of temperature in the fl ows in the tube and in the channel gap. It has been found that the
confi guration of fl ow and its structure in the gap change substantially upon applying the transverse magnetic fi eld,
and also depending on the operating regime of the natural-circulation loop.
Author:  N. A. Luchinkin, N. G. Razuvanov, and O. N. Polyanskaya
Keywords:  liquid metals, hydrodynamics, heat transfer, magnetic fi eld, thermogravitational convection
Page:  438

DEVELOPMENT OF FUSHCHICH'S MATHEMATICAL MODEL OF HEAT TRANSFER

For the fourth-order partial diff erential equation proposed by Fushchich for mathematical description of heat and mass transfer processes, the class of uniqueness and the class of correctness of the Cauchy problem have been established. Using the Fourier transform, a solution to the Cauchy problem is found in an explicit analytical form. It is shown that the new equation does not improve the properties of the classical heat conduction equation, but it allows one to describe heat transfer processes taking into account relaxation eff ects within the framework of the Galileo-invariant mathematical theory of transfer.
Author:  V. I. Korzyuk, Ya. V. Rud'ko
Keywords:  parabolic equation, Cauchy problem, uniqueness class, correctness class, biparabolic heat conduction equation, Fourier transform, Duhamel principle, heat fl ux
Page:  451

ON THE POSSIBILITY OF SYNTHESIS OF SILICON CARBIDE USING AN INDIRECT-ACTION PLASMA GUN

The paper presents the results of experimental and theoretical investigations into the synthesis of silicon carbide using the energy of thermal plasma. The experimental investigations were conducted on a stand with 4 kW of power making it possible to have a thermal plasma fl ow with a bulk temperature of 5600 K. Regimes have been identifi ed for the synthesis of silicon carbide and concentration of composite charge mixture components determining its yield. On the basis of processing experimental data, key characteristics have been calculated for the technological process of silicon carbide synthesis (time and load mass)
Author:  R. D. Gerasimov, V. V. Shekhovtsov, Yu. Z. Vasil′eva, A. Ya. Pak, G. Ya. Mamontov and O. G. Volokitin
Keywords:  synthesis, plasmatron, silicon carbide, carbon, thermal plasma
Page:  463

SIMULATION OF THE THERMIONIC EMISSION OF ELECTRONS AND THE POSSIBILITY OF USING THIS EFFECT FOR THE COOLING OF AIRCRAFT MEMBERS

A numerical simulation of an intense thermionic emission of electrons from the cathode into the air medium in an electrode system has been performed with regard for the possible changes in the voltage across the electrodes and in the electronic work function of the cathode. Spatial distributions of the electrons, the electron energy, the ions, the electric-fi eld strength, and the concentration of the atomic oxygen in the air medium were constructed with the use of a simplifi ed set of kinetic reactions. A possibility of using the thermionic emission of electrons from a cathode for the cooling of the members of fl ying vehicles with the aim to proof them against heat loads was demonstrated. The numerical calculations have shown that the thermionic emission of electrons from the cathode in a system of electrodes with no protective resistor at a high pressure does not provide a cooling of the system.
Author:  P. B. Bulat, K. N. Volkov, I. I. Esakov, A. A. Ravaev, and M. E. Renev
Keywords:  thermionic emission cooling, cooling, gas discharge, plasma, numerical simulation
Page:  471

END-TO-END MATHEMATICAL MODEL OF A RADIO-FREQUENCY INDUCTIVE JET DISCHARGE OF LOWERED PRESSURE

A self-consistent end-to-end model defi ning a radio-frequency inductive jet discharge of lowered pressure (13.3–133 Pa) in an undisturbed gas fl ow and in the presence of a solid body has been proposed. The model comprises three interrelated submodels defi ning the parts of such a discharge, participating in its interaction with the material treated: the plasma jet, the positive-charge layer formed in the neighborhood of the material, and the double electric layer directly near its surface. A peculiarity of the indicated discharge is that, in its plasma jet, a continuous-medium fl ow is changed to a free molecular fl ow, while the fl ow of charged particles in it satisfi es the continuity hypothesis. Because of this, the gasdynamic parameters of the plasma jet are defi ned using the kinetic Boltzmann equation, the fl ow of charged particles in the jet and the positive-charge layer are considered in the hydrodynamic approximation, and the double electric layer formed near the surface of the material is defi ned using the model of a collisionless free molecular fl ow.
Author:  I. Sh. Abdullin,a V. S. Zheltukhin, and A. Yu. Shemakhin
Keywords:  radio-frequency inductive discharge, jet fl ow, positive-charge layer, double electric layer, mathematical model, transient regime of fl ow
Page:  480

MOISTURE SORPTION ISOTHERMS OF A PALM HEART AND PREDICTION OF ITS SHELF LIFE AND THERMODYNAMIC PROPERTIES ON THE BASIS OF THESE ISOTHERMS

Experiments on determination of the sorption isotherms of the heart of a palm at diff erent temperatures have been performed. Some mathematical models, available in the literature, were used to predict the hygroscopic behavior of the palm heart. The thermodynamic properties of the palm heart, such as its isosteric heat of sorption, were determined using the Clausius–Clapeyron equation, and the shelf life of the palm heart was calculated using the Heiss–Eichner prediction model equations with regard for the storage conditions of this product and the requirements for its packaging . The results obtained can be used for optimization of the methods of drying and preservation of palm hearts, which is essential for the enhancement of their quality and the successful promotion of them in the international market.
Author:  A. A. Larbi, A. Mediani, A. Tahri, A. Loumani, A. Djaber, K. Idder, and K. Mebarki
Keywords:  heart of palm, desorption and adsorption isotherms, equilibrium moisture content, isosteric heat, shelf lif
Page:  494

MOISTURE METER FOR LOOSE MATERIALS

A moisture meter for loose materials is proposed that can automatically control the moisture content of a loose material in its continuous fl ow with high accuracy
Author:  P. M. Matyakubova and G. G. Babaev
Keywords:  loose materials, moisture meter
Page:  504

KINETIC MODELS OF COMBUSTION OF KEROSENE

Consideration has been given to the current status of research on the development of kinetic models of combustion of kerosene and its components. Surrogate models of kerosene have been analyzed that describe the physical and chemical properties of an actual fuel and are used in developing detailed and reduced kinetic models. Experimental data have been reviewed based on which testing of the kinetic models with a varying degree of complexity is carried out. Examples of the use of kinetic models in modeling numerically processes occurring in actual power-generating units have been given
Author:  G. Ya. Gerasimov and V. Yu. Levashov
Keywords:  kerosene, hydrocarbons, combustion, kinetic models, computational fl uid dynamics, jet engines
Page:  506

COMPILATION OF DATA ON CONVECTIVE HEAT TRANSFER OF ANNULAR FINNED TUBE BUNDLES WITH AN EXHAUST SHAFT

Air-cooled heat exchangers in various industries enjoy an increasingly wider use thanks to their environmental friendliness and absence of the need for cooling water. Air-cooled heat exchangers from annular fi nned tubes are widely used in chemical, petrochemical, oil-refi ning, gas, and food industries, and also at automobile compressed natural gas fi lling stations (NGV gas stations), in heat power engineering, electric power engineering, refrigeration technology, and at nuclear power plants. The thermal capacity of air-cooled heat exchangers is largely determined by the characteristics of the motion of a fl ow of cooling air through them that can be organized with consumption of electric power by means of a ventilator or in an energy-saving regime by free convection. Unfortunately, the region of ambient air temperatures at which it is possible to use air-cooled heat exchangers under the conditions of free convection is limited. Low heat transfer intensity compared to forced convection is the main drawback of the free-convection regime which is usually compensated by an increase in a heat-emitting area, namely, by fi nning the heat transfer surface. By equipping air-cooled heat exchangers with additional devices making it possible to intensify free convection, the thermal performance of heat exchangers can be improved signifi cantly. The paper provides an overview of experimental and numerical investigations of free-convection heat transfer in annular fi nned tube bundles with an exhaust shaft installed above them.
Author:  A. B. Sukhotskii, G. S. Marshalova and E. S. Danil′chik
Keywords:  bimetallic annular fi nned tube, heat transfer bundle, Nusselt number, Grashof number, Rayleigh number, exhaust shaft, mixed convection
Page:  525

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