Table of contents

Editor Alexey V. Dedov

Organizers

The Ministry of Education and Science of the Russian Federation

The Russian Academy of Sciences

National Committee for Heat and Mass Transfer

National Research University "Moscow Power Engineering Institute"

The Institute of Thermophysics SB RAS named S.S. Kutateladze

Conference sponsors

Russian Foundation for Basic Research

Comsol

GazEcos

Interenergo

Introduction

The International Conference "Problems of Thermal Physics and Power Engineering" (PTPPE-2017) held at Moscow, Russia on October 9-11, 2017. The conference will take place in the National Research University "Moscow Power Engineering Institute" (NRU "MPEI")

Lists of Scientific and Organizing Committee members are available in this pdf.

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

The paper presents the generalized correlations for the heat transfer coefficients for natural convection boiling of microfinned surfaces based on the experimental measurements.

The oxidative recrystallization of spent nuclear fuel running in the vibrofluidized bed mode requires a continuous supply or removal of heat, which can be performed using various techniques. The most advantageous of these is supplying a coolant gas over the surface of the vibrofluidized bed. However, the available information about such heat exchange processes is limited. External heat exchange between the surface of the vibrofluidized bed and the blown coolant gas was investigated using fuel simulators, which construction was based on narrow-fraction electrocorundum exhibiting the particle size of d_P = 0,07 ÷ 1,25 mm in a device with the diameter of 100 mm and the height of 160 mm according to a stationary technique. The data on the influence of the coolant flow, the amplitude and frequency of vibration, as well as the particle size of the dispersed material were obtained. In order to explain the results obtained, we used data on the pulsations of the gas flow velocities occurring in the vibrofluidized bed and depending on the parameters listed above.

Results from the experimental and numerical simulations on the flow structure and heat transfer in polydisperse bubbly flows in a sudden pipe expansion are presented. The addition of air bubbles results in a significant increase in the heat transfer rate (up to 300%). These effects are augmented by increasing the gas volumetric flow rate ratio. The largest heat transfer enhancement was observed in flow relaxation zone after the reattachment point.

The article contains a simplified model of a wave motion of the atmospheric surface of planets containing finely dispersed particles of condensed gases, it is assumed that the surface of planets is heated above the saturation temperature of gas condensate, and the surface layers of the foggy atmosphere are strongly cooled. The mechanism of formation and growth of such waves is proposed and justified. It was found that the existence of growing waves on the surface of such an atmosphere is possible, as well as, in the course of time, the formation of a vortex in the atmosphere around the planet. Perturbations of the atmosphere thickness lead to the formation of gravitational waves propagating along its surface. The thickness of the atmosphere at the crest of the wave is greater than that in the trough. While the temperature of the atmosphere under the ridge increases, it decreases under the trough due to shielding of the thermal radiation of the planet. When the crest of a gravitational wave moves, the atmosphere under the trailing edge of the crest has a temperature higher than that under the front edge, since the trailing edge of the crest is heated more intensively by radiation from the surface of the planet. The partial pressure of the vapor of the condensed gases at the rear edge of the ridge is higher than that at the front edge; the work of the pressure difference during the motion of the ridge increases its energy and height. The authors demonstrate the analogy between the mechanisms of wave growth in a foggy atmosphere of planets and the mechanism of wave growth in a thin vapor layer between a strongly heated solid surface or a metal melt and a volatile liquid.

Distribution function on potential energy in a strong correlated system can be calculated analytically. In an equilibrium system (for instance, in the bulk of the liquid) this distribution function depends only on temperature and mean potential energy, which can be found through the specific heat of vaporization. At the surface of the liquid this distribution function differs significantly, but its shape still satisfies analytical correlation. Distribution function on potential energy nearby the evaporation surface can be used instead of the work function of the atom of the liquid.

Some new experimental results of continuum mechanics problems in two-phase systems are described. The processes of heat and mass transfer during cooling of strong heated sphere in the subcooled liquid are studied. Due to high level of heater temperature the stable vapor film is formed on the sphere surface. Calculation of steady-state transport processes at vapor – water interface is carried out using methods of molecular-kinetic theory. Heat transfer in vapor by thermal conductivity and natural convection in liquid are considered. Pressure balance is provided by hydrostatic pressure and non-equilibrium boundary condition. The results of the calculations are analyzed by comparison with previous data and experimental results.

The influence of electric field, interelectrode spacing, and heat-release surface orientation on heat transfer at boiling on a porous surface is studied. With increase in heat flow density the influence of a field decreases up to degeneration. The local characteristics of the heat transfer coefficient indicate an significant heat transfer enhancement in the case of a permeable electrode in comparison with a solid electrode which increases with the growth in the field intensity. The influence of electric field on the dynamics of vapor bubble growth is investigated. There have been obtained the expressions for the vapor bubble diameter and heat flow density without and under electric field which agree satisfactorily with the experimental data.

Experimentally studying of subcooled water boiling in rectangular channel electrically heated from one side was conducted. Flat surfaces, both smooth and coated by microarc oxidation technology, were used as heating surfaces. The tests were conducted at atmospheric pressure in the range of mass flow rate from 650 to 1300 kg/(m² s) and water subcooling relative to saturation temperature from 23 to 75 °C.

Using high-speed filming a change in the two-phase flow structure and its statistic characteristics (nucleation sites density, vapor bubble distribution by size, etc.) were studied. With an increase in the heat flux density (with the mass flow rate and subcooling being the same) and amount and size of the vapor bubbles increased also. At a relatively high heat flux density, non-spherical vapor agglomerates appeared at the heating surface as a result of coalescence of small bubbles. They originated in chaotic manner in arbitrary points of the heating surface and then after random evolution in form and size collapsed. The agglomerate size reached several millimeters and their duration of life was several milliseconds. After formation of large vapor agglomerates, with a further small increase in heat flux density a burnout of the heating surface occurred. In most cases the same effect took place if the large agglomerates were retained for several minutes.

The results of the numerical simulation of pulsations in the Laval-liked vapour channel of short low-temperature range heat pipes (HPs) are presented. The numerical results confirmed the experimentally obtained increase of the frequency of pulsations in the vapour channel of short HPs with increasing overheat of the porous evaporator relative to the boiling point of the working fluid. The occurrence of pressure pulsations inside the vapour channel in a short HPs is a complex phenomenon associated with the boiling beginning in the capillary-porous evaporator at high heat loads, and appearance the excess amount of vapour above it, leading to the increase in pressure P to a value at which the boiling point T_B of the working fluid becomes higher than the evaporator temperature T_ev. Vapour clot spreads through the vapour channel and condense, and then a rarefaction wave return from condenser in the evaporator, the boiling in which is resumed and the next cycle of the pulsations is repeated. Numerical simulation was performed using finite element method implemented in the commercial program ANSYS Multiphisics 14.5 in the two-dimensional setting of axis symmetric moist vapour flow with third kind boundary conditions.

An experimental and numerical process simulation of evaporation of a suspended droplet of a non-ideal solution liquid streamlined by a gas flow was carried out in this paper. For analyze the heat and mass transfer of an evaporating droplet a mathematical model is given, which makes it possible to calculate both ideal and non-ideal solutions and takes into account the thermal losses in the holder. The experimental part of the study contains data on the evaporation of droplets of various compositions. The experimental data obtained by the authors were compared with the developed numerical model in the research.

New experimental data on superheated water atomization is presented. It is shown that in contrast to the case of short cylindrical nozzles, which provide bimodal water-droplet sprays, the application of divergent nozzles makes it possible to obtain one-modal water atomization with droplets of about micron diameter being obtained. This fact is due to changes in the mechanism of superheated water jet fragmentation and it is very important for engineering applications. A modified experimental technique for processing integral monochromatic scattering indicatrix was developed and tested. In addition, a new calculation code was worked out for calculating atomized water drop-size distribution (on the basis of Mi theory) in micron and submicron ranges.

The process of heat transfer in an evaporation-condensation system (ECS) at circulation of dielectric liquid in a closed thermoelectrohydrodynamic (TEHD) loop consisting of an evaporator, a condenser and electrohydrodynamic (EHD) pump for pumping of heat carrier, is considered. Previously, the authors studied the dependence of heat transfer on the angle of rotation of TEHD loop in a vertical plane. The report contains the results of studies of heat transfer at electrohydrodynamic pumping of the heat carrier (8% solution of acetone in Freon 113) in the condenser area by means of EHD pump of "cone-cone" type. All elements of the ECS are arranged in a horizontal plane and the heat transfer from the heater to the condenser without EHD pumping is impossible. A pulsating heat carrier flow mode, depending on the heat input and the voltage applied to the pump, takes place at EHD pumping. As the input power is decreasing the frequency of the coolant pulsations as well as the departure diameter and number of vapour bubbles are also decreasing. At some critical heat input the pulsations disappear and the transition from turbulent mode to the laminar one takes place causing the decrease of the heat transfer coefficient. The increase of the pumping flow rate by raising the voltage applied to the EHD pump, results in a partial suppression of boiling. The maximum intensification of heat transfer is reached at pulsation frequency of 1.25 Hz. The maximum heat flow from the heater was 4.2·10⁴ W/m². Graphical representation and the physical interpretation of the results, which reflect the essence of the process, are given.

A goal of the study is development of an approximate but well-grounded model of entrainment/deposition processes in annular two-phase flow at high reduced pressures (p/p_cr>0.45). Nakazatomi and Sekoguchi (1996) have presented the unique experimental data on liquid distribution between the core and the film in air/water two-phase flow at high pressures, up to 20 MPa; at pressures higher 10 MPa the data feature with abnormally high fraction of entrained liquid and manifest very strong deviation from any known empirical correlations, including the recent one by Cioncolini and Thome (2012). In deducing the approximate model of droplets entrainment, we used the experimental observations, according to which a liquid film becomes thin and smooth at high reduced pressures. A plenty of tiny droplets detach from the liquid film surface at the points, which spacing is determined as a length scale in Weber number for gas flow. This spacing and the liquid film thickness are assumed being the parameters controlling a droplet departure diameter. These assumptions allow developing an equation for calculating entrainment intensity at high reduced pressures. A balance between the flows of droplets entrainment and deposition due to turbulent diffusion corresponds to the dynamic equilibrium. The equation based on this balance contains one unknown numerical factor and allows one to calculate liquid distribution in a channel cross section. Comparing the calculation results with the experimental data for the water–air flows at high reduced pressures (more than 0.45) has shown their good agreement at the universal value of the numerical constant.

Film boiling regime occurs when temperature of solid surface exceeds the attainable limiting temperature of the cooling liquid. In unsteady conditions, this boiling regime has applications in safety systems of Nuclear Power Plants (NPP) and in metal-processing. Nonsteady film boiling of subcooled water has unresolved issues relating to the conditions when low-intensive stable film boiling regime turns to a high intensive mode. The present paper considers the new experimental results on unsteady film boiling of ethanol over a wide range of subcoolings. On the basis of the experimental data, a hypothesis has been developed to explain appearance of the intensive heat transfer during film boiling.

The results of earlier performed work are summarized. Formulae for the absolute values of the following variables: the radius of the vapour bubble, the velocity and acceleration of its growth, the specific and total heat flux through the interphase surface of the bubble, the liquid overheating and the heat transfer coefficient, sound pressure in one- and three-dimensional cases are presented. On their basis, the relationship between the relative values of the pairs of these variables because of time elimination is derived.

The technology of low-temperature process of desalting of water is offered. Realization of this technology assumes partial evaporation of water in adiabatic steam generator, formation of two-phase stream, separation and condensation steam-phase. Results of numerical modeling of the processes in steam generator are presented, also productivity steam generator is determined.

An experimental study on conditions and main characteristics for high-temperature (more than 700 K) evaporation of oil-water drops is presented. The high-temperature water purification from impurities can be the main practical application of research results. Thus, the heating of drops is implemented by the two typical schemes: on a massive substrate (the heating conditions are similar to those achieved in a heating chamber) and in a flow of the heated air. In the latter case, the heating conditions correspond to those attained while moving water drops with impurities in a counter high-temperature gaseous flow in the process of water purification. Evaporation time as function of heating temperature is presented. The influence of oil product concentration in an emulsion drop on evaporation characteristics is discussed. The conditions for intensive flash boiling of an emulsion drop and its explosive breakup with formation of the fine droplets cloud are pointed out. Heat fluxes required for intensive flash boiling and explosive breakup of a drop with further formation of the fine aerosol are determined in the boundary layer of a drop. The fundamental differences between flash boiling and explosive breakup of an emulsion drop when heated on a substrate and in a flow of the heated air are described. The main prospects for the development of the high-temperature water purification technology are detailed taking into account the fast emulsion drop breakup investigated in the paper.

The problems of the carrying out experimental investigations of the superfluid helium boiling on a cylindrical heater placed in the porous body are considered. The scheme of installation is presented. The experimental cell, control and measuring devices, and devices for video recording and data processing are described. The technique of carrying out the experiments and the analysis of the obtained experimental results and their discussion are given.

The results of experimental study of thermo and hydraulic characteristics of flow boiling of water and FC-72 in natural circulation loop under atmospheric pressure are presented. The experimental data have been obtained in the range of wall heat flux densities (6 – 70) kW/m² for water and (4.6 – 30) kW/m² for FC-72. These two liquids differ substantially in thermophysical properties so it makes it possible to extend the range of reduced pressures almost for an order of magnitude without changing the technical parameters of experimental setup. An additional information for the analysis of flow pattern influence on onset of instability and unstable circulation mechanism have been obtained as the result. The flow up tube of the loop had inner diameter 9.1 mm and consisted of two section – heated one 98 diameters length (that is 65 % of total tube length) and upper adiabatic section with length 48 diameters. Different circulation regimes were realized in experiments: mixed regimes with single phase and boiling zones in the heated part of the tube and boiling regimes along the full length of the heated section. The experimental data on circulation velocity (flow rate) and wall temperature distributions (including pulsating components of temperature and velocity) are presented in dependence on wall heat flux density and liquid subcooling at the inlet to the heated zone. At water experiments autooscillating regimes of boiling flows were observed within the whole range of inlet liquid subcoolings up to saturation temperature and at all wall heat flux densities from lowest one (10 kW/m²) to somewhat upper limiting value of 64 kW/m². At higher heat fluxes the two-phase boiling flow was stable not only in saturation inlet liquid temperature but also at low subcoolings. In FC-72 experiments the flow was stable at all realized heat flux densities within the range of inlet liquid subcoolings (2 – 20) °C.

The paper is devoted to research of the heat and mass transfer processes on the vapor-liquid interface. These processes can be realized for example at metal tempering, accidents at nuclear power stations, followed by the release of the corium into the heat carrier, getting hot magma into the water during volcanic eruptions and other. In all these examples the vapor film can arise on the heated body surface. In this paper the vapor film formation process will be considered with help of molecular dynamics simulation methods. The main attention during this process modeling will be focused on the subject of the fluid and vapor interactions with the heater surface. Another direction of this work is to study of the processes inside the droplet that may take place as result of impact of the high-power laser radiation. Such impact can lead to intensive evaporation and explosive destruction of the droplet. At that the duration of heat and mass transfer processes in droplet substance is tens of femtoseconds. Thus, the methods of molecular dynamics simulation can give the possibilities describe the heat and mass transfer processes in the droplet and the vapor phase formation.

The influence of micro- and nanostructured surfaces on the boiling characteristics is introduced. The working surfaces were obtained by processing the samples with a laser, plasma, electron, or ion beam. Some of the samples were preliminarily coated with nanocarbonic materials. The morphology and the contact angle of wetting during interaction with water were studied for surfaces. A description of the apparatus for investigating the Leidenfrost temperature is introduced.

Working fluids based on mixtures are widely used in cryogenic and refrigeration engineering. One of the main elements of low-temperature units is a recuperative heat exchanger where the return flow cools the direct (cold regeneration is carrying out) resulting in continuous boiling and condensation of the multicomponent working fluid in the channels. The temperature difference between the inlet and outlet of the heat exchanger can be more than 100K, which leads to a strong change in thermophysical properties along its length. In addition, the fraction of the liquid and vapor phases in the flow varies very much, which affects the observed flow regimes in the heat exchanger channels. At the moment there are not so many experimental data and analytical correlations that would allow to estimate the heat transfer coefficient during the flow of a two-phase mixture flow at low temperatures. The work is devoted to the study of the boiling process of multicomponent working fluids used in refrigeration and cryogenic engineering. The description of the method of determination of heat transfer coefficient during boiling of mixtures in horizontal heated channel is given as well as the design of the experimental stand allowing to make such measurements. This stand is designed on the basis of a refrigeration unit operating on the Joule-Thomson throttle cycle and makes it possible to measure the heat transfer coefficient with a good accuracy. Also, the calculated values of the heat transfer coefficient, obtained with the use of various correlations, are compared with the existing experimental data. Knowing of the heat transfer coefficient will be very useful in the design of heat exchangers for low-temperature units operating on a mixture refrigerant.

The set of equations which describes a non-steady 3D flow of non-isothermal liquid film in the presence of thermocapillary effect is deduced in the long-wave approach. The used model is applicable for moderate Reynolds's numbers Re∼10 and does not imply in advance set the profile of temperature in a film. The linear analysis of a stability of a film in relation to perturbations in spanwise direction is carried out and dispersion relations are gained. Nonlinear development of instability is investigated numerically in cases of 2D and 3D flow and appearance of quasistationary rivulet structure. Influence of dimensionless parameteres on characteristic scales of rivulet structures is revealed.

This paper continues the numerical modeling of Stokes flows near cavities of a superhydrophobic surface, occupied by gas bubbles, based on the Boundary Element Method (BEM). The aim of the present study is to estimate the friction reduction (pressure drop) in a microchannel with a bottom superhydrophobic surface, the texture of which is formed by a periodic system of striped rectangular microcavities containing compressible gas bubbles. The model proposed takes into account the streamwise variation of the bubble shift into the cavities, caused by the longitudinal pressure gradient in the channel flow. The solution for the macroscopic (averaged) flow in the microchannel, constructed using an effective slip boundary condition on the superhydrophobic bottom wall, is matched with the solution of the Stokes problem at the microscale of a single cavity containing a gas bubble. The 2D Stokes problems of fluid flow over single cavities containing curved phase interfaces with the condition of zero shear stress are reduced to the boundary integral equations which are solved using the BEM method.

This paper presents an experimental setup and experimental data for critical heat flux. The hydraulic loop of the experimental setup allows it to maintain stable flow parameters at the inlet of the test section at pressures up to 2.7 MPa and temperatures up to 200 °C. Experiments of hydrodynamics and heat transfer were performed for R113 and RC318 in two vertical channels with diameters of 1.36 and 0.95 mm and lengths of 200 and 100 mm, respectively. The inlet pressure-to-critical pressure ratio (reduced pressure) was p_r = p/p_cr = 0.15 ÷ 0.9, the mass flux ranges were between 700 and 4800 kg/(m²s), and inlet temperature varied from 30 to 180 °C. The primary regimes were obtained for conditions that varied from highly subcooled flows to saturated flows. For each regime with fixed parameters, the maximum possible heating power value was applied, with the maximum limited by the maximum output of the power supply, the onset of dryout, or wall temperatures exceeding 350 °C. The influence of flow conditions (i.e., mass flow rate, pressure, inlet temperature, and the channel diameter) on the critical heat flux is presented.

The present work is dedicated to verification of numerical model in standard solver of open-source CFD code OpenFOAM for two-phase flow simulation and to determination of so-called "baseline" model parameters. Investigation of heterogeneous coolant flow parameters, which leads to abnormal friction increase of channel in two-phase adiabatic "water-gas" flows with low void fractions, presented.

At present, it is obvious that the problem of the tornado is important not only for our planetЮ to determine the conditions for the formation of a tornado, it is required to take into account a number of hydrodynamic and plasma processes [1 - 6]. Along to prediction of a tornado generation conditions [1 - 3] it is necessary to evaluate the characteristics of its quasi-stationary motion in a formed funnel: the mass of the moving moist air involved in the funnel and the size and form of the funnel. For a complete description of the phenomena, it is necessary to involve numerical calculations. We note that even for numerical calculations using powerful computers, the problem is very difficult because of the need to calculate multiphase turbulent flows with free, self-organizing boundaries [1, 6]. However, "strict" numerical calculations, it is impossible to do without the use of many, often mutually exclusive, models. For example, how to choice an adequate model of turbulence (algebraic, k-ε model, etc.) or the use of additional, often not accepted, hypotheses about certain processes used in calculations (mechanisms on the nature of moisture condensation, etc.). Therefore, along with numerical calculations of such flows, modeling problems that allow an exact solution and allow to determine the most important and observed characteristics of a tornado.

Using the conductometric technique, the process of contact of subcooled distilled water with a hot surface was studied. The results of measurements of the parameters of the contact made in the range of the temperature change of the heated surface 170 ± 620 ° C are given. An experimental fact has been revealed, which indicates that a transition from film to bubble boiling is preceded by a short (several millisecond) hydrodynamic process that is characterized by intense interaction of waves at the vapour - liquid interface with the heated surface. With the help of wavelet analysis, the amplitude-frequency characteristics of this process are investigated and a qualitative physical model of its flow

The development of power plants focuses on increasing the parameters of water coolants up to a supercritical level. Depressurization of the unit circuits with such a coolant leads to emergency situations. Their scenarios can change significantly with the variation of initial pressure and temperature before the start of depressurization. When the pressure drops from the supercritical single-phase region of the initial thermodynamic parameters of the coolant, either the liquid boils up, or the vapor is condensed. Because of the rapid pressure decrease, the phase transition can be non-equilibrium that must be taken into account in the simulation. In the present study, an axisymmetric problem of the outflow of a water coolant from the pipe butt-end is considered. The equations of continuity, momentum and energy for a two-phase homogeneous mixture are solved numerically. The vapor and liquid properties are calculated using the TTSE software package (The Tabular Taylor Series Expansion Method). On the basis of the computer complex LCPFCT (The Flux-Corrected Transport Algorithm) the program code was developed for solving numerous problems on the depressurization of vessels or pipelines, containing superheated water or gas under high pressure. Different variants of outflow in the external model atmosphere and generation of waves are analyzed. The calculated data on the interaction of pressure waves with a barrier are calculated. To describe phase transitions, an asymptotic relaxation model of nonequilibrium evaporation and condensation has been created and tested.

A new combined fully Lagrangian approach to numerical simulation of axially symmetric vortex ring-like flows (in the absence of swirl) is proposed. The method is applicable to simulation of unsteady viscous flows with a dilute admixture of non-colliding particles which do not affect the carrier phase. The novel approach is based on a modification and combination of two Lagrangian methods: the carrier phase parameters are calculated using the vortex method based on diffusion velocity and the dispersed phase parameters (including the concentration) are calculated using the full Lagrangian approach. The application of the method is illustrated by two examples of numerical calculations of transient two-phase vortex ring-like flows.

Sprays with a periodic supply drop phase have great opportunities to control the processes of heat transfer. We can achieve optimal evaporative modes of cooling by changing the pulse duration and the repetition frequency while minimizing flow of the liquid phase. Experimental data of investigation of local heat transfer for poorly heated large surface obtained on the original stand with multi nozzle managed the irrigation system impact of the gas-droplet flow present in this work. Researches on the contribution to the intensification of spray options were conducted. Also the growth rate was integral and local heat. Information instantaneous distribution of the heat flux in the description of the processes have helped us. Managed to describe two basic modes of heat transfer: Mode "insular" foil cooling and thick foil with forming of streams. Capacitive sensors allow to monitor the dynamics of the foil thickness, the birth-belt flow, forming and the evolution of waves generated by "bombing" the surface with the droplets.

The heat supply by means of heat pumps is considered now as a rational method of local heating which can lead to economy of primary fuel. At use of low-potential heat, for example, the heat of a ground (5 ... 18 °C) or ground waters (8 ... 10°C) only small depressing of temperature of these sources (on 3 ... 5°C) is possible that demands application of heat exchangers with intensified heatmass transfer surfaces. In thermal laboratory of TOT department the 200 W experimental installation has been developed for research of process of boiling of freon R134a. The principle of action of the installation consists in realisation of reverse thermodynamic cycle and consecutive natural measurement of characteristics of elements of surfaces of heat exchangers of real installations at boiling points of freon from-10°C to +10°C and condensing temperatures from 15°C to 50 °C. The evaporator casing has optical windows for control of process of boiling of freon on ribbed on technology of distorting cut tubes. Temperature measurement in characteristic points of a cycle is provided by copper-constantan thermocouples which by means of ADT are connected to the computer that allows treat results of measurements in a real time mode. The structure of a two-phase flow investigated by means of the optical procedure based on laser technique.

The paper presents the review results of heat transfer at boiling in channels with twisted tape inserts. Various methods and approaches to the research of heat transfer processes at boiling of refrigerants in channels with twisted tape inserts were identified, a significant difference of the influencing factors on the heat transfer depending on the range of regime parameters under study was noted and also the necessity for research in this field was shown.

At present, there is no sufficiently reliable and physically proved method for calculating the heat exchange coefficient in boiling of non-azeotropic mixtures. The main cause is complexity of the mechanism of boiling since non-azeotropic mixtures have the temperature glide (i.e. non-isothermal phase transition). The experimental results at boiling of non-azeotropic mixtures in horizontal smooth steel and copper pipes have been selected for the theoretical analysis. The experimental data for the nucleate boiling were compared to calculations on various theoretical dependences. The calculated heat transfer coefficient is proposed by Gogonin's dependence (2006). The mentioned dependence taking into account the influence of physical properties of a wall and its roughness on a heat exchange coefficient, results in the best coincidence to experimental data.

The paper presents the results of experimental study of heat transfer in the film flow of R114/R21 refrigerant mixture on the vertical thin-wall copper cylinders with microstructured outer surfaces. Microstructuring is made by the method of deforming cutting with subsequent rolling by a straight knurl roller along the fin tops. The pitch of micro-finning was 100 or 200 μm and height was 220 or 440 μm, respectively. The knurling pitch in both cases was 318 μm. The film Reynolds number was varied in the range of 300-1500. The heat flux density was step-by-step increased from zero to the values corresponding to the boiling crisis. It is shown that the heat transfer coefficients at nucleate boiling on the studied surfaces with microstructuring exceed the corresponding values for a smooth surface more than by 3 times, the critical heat flux increases more than twice.

The numerical modeling results for the heat transfer during cooling a metal cylinder by a gas-liquid medium flow in an annular channel are presented. The results are obtained on the basis of the mathematical model of the conjugate heat transfer of the gas-liquid flow and the metal cylinder in a two-dimensional nonstationary formulation accounting for the axisymmetry of the cooling medium flow relative to the cylinder longitudinal axis. To solve the system of differential equations the control volume approach is used. The flow field parameters are calculated by the SIMPLE algorithm. To solve iteratively the systems of linear algebraic equations the Gauss-Seidel method with under-relaxation is used. The results of the numerical simulation are verified by comparing the results of the numerical simulation with the results of the field experiment. The calculation results for the heat transfer parameters at cooling the high-temperature metal cylinder by the gas-liquid flow are obtained with accounting for evaporation. The values of the rate of cooling the cylinder by the laminar flow of the cooling medium are determined. The temperature change intensity for the metal cylinder is analyzed depending on the initial velocity of the liquid flow and the time of the cooling process.

Low flow natural circulation regimes are realized in many practical applications and the existence of the reliable engineering and design calculation methods of flows driven exclusively by buoyancy forces is an actual problem. In particular it is important for the analysis of start up regimes of passive safety systems of nuclear power plants. In spite of a long year investigations of natural circulation loops no suitable predicting recommendations for heat transfer and friction for the above regimes have been proposed for engineering practice and correlations for forced flow are commonly used which considerably overpredicts the real flow velocities. The 2D numerical simulation of velocity and temperature fields in circular tubes for laminar flow natural circulation with reference to the laboratory experimental loop has been carried out. The results were compared with the 1D modified model and experimental data obtained on the above loop. The 1D modified model was still based on forced flow correlations, but in these correlations the physical properties variability and the existence of thermal and hydrodynamic entrance regions are taken into account. The comparison of 2D simulation, 1D model calculations and the experimental data showed that even subject to influence of liquid properties variability and entrance regions on heat transfer and friction the use of 1D model with forced flow correlations do not improve the accuracy of calculations. In general, according to 2D numerical simulation the wall shear stresses are mainly affected by the change of wall velocity gradient due to practically continuous velocity profiles deformation along the whole heated zone. The form of velocity profiles and the extent of their deformation in its turn depend upon the wall heat flux density and the hydraulic diameter.

The results of an experimental study of the hydrodynamics of a perforated plate with a layer of balls adjoining to it are presented herein. The experiments were carried out in the fluid flow range from 0.1 to 0.6 kg/s, at a fluid temperature of 19 °C.

Mixed convection is a common type of heat transfer for relatively slow impinging flows. When fluid flow impinges a transverse flat plate a Hiemenz flow appears. It is basically driven by buoyancy forces, which make it unstable and challenging to simulate. The present study is dedicated to these challenges in terms of computational mesh reduction. Several methods of mesh reduction were tested, including computational domain simplification, symmetry application and mesh coarsening. Each simplification method was tested against experimental data to evaluate proposed hypotheses about symmetry applicability and unconditional advantage of finer meshes. All considered cases were simulated with previously validated numerical model. Although simulated process was seemingly purely symmetrical, it didn't respond well to implementation of symmetrical boundary conditions. Simplification of computational domain yielded generally expected results showing significant deterioration after truncation of essential part of domain. Mesh coarsening led to erroneous results as well, but dependency wasn't linear. Statistical analysis proved normality of simulation errors distribution. The present study addresses preprocessing stage of simulation process, providing some insight into simplification methods of computational mesh.

The equation describing the heat exchange of a stream in a pipe is derived from the dependences for the turbulent boundary layer and the conservativeness of its characteristics. The equation includes the parameter considering a variability of physical properties in a flow area. The variability of properties affect the heat exchange for gases of more and less atomicity with different ways and it depends on the Reynolds number of the flow. The results of obtained formula evaluation are compared with the theoretical and experimental data of other authors.

A system of differential equations (Navier-Stokes, continuity, heat conductivity) is used to solve convective heat transfer problems. While solving Navier-Stokes equation, it is usually assumed that tangent stress is proportional to the velocity gradient. This assumption is valid with a small velocity gradient, for example, near an axis of the channel, but velocity gradient can be very large near the channel wall. Our paper shows that if we accept power law instead of linear law for tangential stress, then the velocity profile for creeping, laminar, and turbulent flow in the channel can be calculated without using Navier-Stokes equation. Also, in this case Navier-Stokes equation itself changes: the coefficient of dynamic viscosity changes its value from normal (in case of the creeping flow) to tending to infinity (in case of the well-developed turbulent flow).

As part of the component development of TsAGI's new subsonic wind tunnel where the air flow velocity in the closed test section is up to 160 m/sec hydraulic and thermal characteristics of air cooler are calculated. The air cooler is one of the most important components due to its highest hydraulic resistance in the whole wind tunnel design. It is important to minimize its hydraulic resistance to ensure the energy efficiency of wind tunnel fans and the cost-cutting of tests. On the other hand the air cooler is to assure the efficient cooling of air flow in such a manner as to maintain the temperature below 40 °C for seamless operation of measuring equipment. Therefore the relevance of this project is driven by the need to develop the air cooler that would demonstrate low hydraulic resistance of air and high thermal effectiveness of heat exchanging surfaces; insofar as the cooling section must be given up per unit time with the amount of heat Q=30 MW according to preliminary evaluations. On basis of calculation research some variants of air cooler designs are proposed including elliptical tubes, round tubes, and lateral plate-like fins. These designs differ by the number of tubes and plates, geometrical characteristics and the material of finned surfaces (aluminium or cooper). Due to the choice of component configurations a high thermal effectiveness is achieved for finned surfaces. The obtained results form the basis of R&D support in designing the new subsonic wind tunnel.

In the framework of TsAGI's supersonic wind tunnel modernization program aimed at improving flow quality and extending the range of test regimes it was required to design and numerically validate a new test section and a set of shaped nozzles: two flat nozzles with flow Mach number at nozzle exit M=4 and M=5 and two axisymmetric nozzles with M=5 and M=6. Geometric configuration of the nozzles, the test section (an Eiffel chamber) and the diffuser was chosen according to the results of preliminary calculations of two-dimensional air flow in the wind tunnel circuit. The most important part of the work are three-dimensional flow simulation results obtained using ANSYS Fluent software. The following flow properties were investigated: Mach number, total and static pressure, total and static temperature and turbulent viscosity ratio distribution, heat flux density at wind tunnel walls (for high-temperature flow regimes). It is demonstrated that flow perturbations emerging from the junction of the nozzle with the test section and spreading down the test section behind the boundaries of characteristic rhomb's reverse wedge are nearly impossible to eliminate. Therefore, in order to perform tests under most uniform flow conditions, the model's center of rotation and optical window axis should be placed as close to the center of the characteristic rhomb as possible. The obtained results became part of scientific and technical basis of supersonic wind tunnel design process and were applied to a generalized class of similar wind tunnels.

The paper describes some features of hydrodynamics and heat exchange in cooling systems of optical units of laser active mirrors. The experimental data on hydraulic resistance and heat transfer are given and summarized for the cooling systems which are the most suitable to such applications – a channel system with an intermittent wall and a wafer cooling system.

Heat transfer in channels with the pressure gradient has been studied experimentally. The considered rectangular channel had a diverging and a converging section. Air under atmospheric conditions at the channel inlet was considered as a heat-transfer fluid. Steady and pulsating flow regimes were studied at different frequencies and amplitudes of forced pulsations generated by a rotating flap periodically blocking the channel cross section. The effect of forced flow pulsations on heat transfer in channels with the pressure gradient has been described.

An influence of upstream pipe bends on the thermal mixing in T-junctions has been investigated with the use of Improved Delayed Detached Eddy Simulation, which accuracy for such flows has been justified by a comparison against the experiment. The parametrical study of T-junctions with various upstream pipe bends has shown that the most dangerous in terms of the thermal fatigue are configurations with the branch pipe and upstream bend pointing in different directions, especially in case when the bend is located relatively close to the junction.

Efficiency of supersonic pipe for temperature stratification with finned subsonic surface of heat transfer is the major of this paper. Thermal and hydraulic analyses of this pipe were conducted to asses effects from installation of longitudinal rectangular and parabolic fins as well as studs of cylindrical, rectangular and parabolic profiles. The analysis was performed based on refined empirical equations of similarity, dedicated to heat transfer of high-speed gas flow with plain wall, and Kármán equation with Nikuradze constants. Results revealed cylindrical studs (with height-to-diameter ratio of 5:1) to be 1.5 times more efficient than rectangular fins of the same height. At the same time rectangular fins (with height-to-thickness ratio of 5:1) were tend to enhance heat transfer rate up to 2.67 times compared to bare walls from subsonic side of the pipe. Longitudinal parabolic fins have minuscule effect on combined efficiency of considered pipe since extra head losses void any gain of heat transfer. Obtained results provide perspective of increasing efficiency of supersonic tube for temperature stratification. This significantly broadens device applicability in thermostatting systems for equipment, cooling systems for energy converting machinery, turbine blades and aerotechnics.

Materials submitted provide for the research results of the problem of scale formation in heat exchangers and show results of calculations of scale type and thickness impact on heat transfer factor and on heat exchanger overall energy efficiency with regard to heat exchanger hydraulic resistance increase. Calculations have been carried out using the example of heat exchanger PV1 (∏B1) 219-2-G-1, 6-6-UZ, manufactured as per State Standard (GOST) 27590-2005. On the basis of calculations performed recommendations on maximum allowable thickness of scale crust of different type, after scaling of which the heat exchanger operation may infringe the technological process, have been elaborated.

Visualization of the pulsating cross-flow past the in-line and staggered tube bundles has been performed. The frequency and amplitude of forced flow pulsations and the tube pitch in the bundle varied in the experiments. The main attention was focused on the flow pattern in the near wake of the third-row tube. The most indicative regimes of flow past a tube in a bundle have been revealed depending on forced flow unsteadiness parameters. The obtained data have been generalized in the flow maps in the space of dimensionless frequency (Strouhal number, St) and relative pulsation amplitude, β, individually for the in-line and staggered tube arrangement. Three most indicative regimes of pulsating flow past the tubes in a bundle have been singled out in each flow map.

In this report the assessment of the results of recent experimental investigations of heat transfer in turbulent flow of supercritical water and modeling fluids (carbon dioxide, Freon) in vertical channels of different geometry (tubes, annular gaps and rod bundles) is presented. The conditions of similarity and the system of criteria, which determine the intensity of heat exchange in the fluids near the critical point, are considered. Due to the small hydraulic diameter of the heat exchange channels in the core of nuclear reactors it is possible to neglect the gravitational forces compared to the acceleration caused by the thermal inertia effects and the forces of viscosity. Based on these ideas two comprehensive criteria were proposed. Their application in the basic equation of heat transfer suggested by the authors earlier for the normal regimes satisfactorily (with an error of 20–25%) describes the features of change of heat transfer coefficient in the deteriorated and mixed regimes of heat transfer. The system of equations suitable for engineering calculation of heat transfer in channels of nuclear reactors cooled with supercritical pressure water was developed.

In this paper the method of modelling of high-speed nonequilibrium two-phase turbulent flows with phase transition in disperse phase is presented. The method proposed in this paper has the following features: 1) the mathematical model includes conservation equations for gas and solid particles, as well as the equations for gas vibration molecular energy, conservation of species and phase transition equation for particles; 2) the equations for the particles are solved mixed Euler-Lagrange formulation; 3) the solver algorithm is two-way coupled; 4) a special turbulence model taking into account the effect of flow compressibility is implemented. The main case considered in this paper is crystallization process of aluminium oxide Al2O3 particles in underexpanded jet flow with cross-flow at different angles of attack. Simulation results for jets of different configuration are presented.

Frost on fin surfaces of the heat exchanger increases thermal resistance and blocks air flow passage, which reduces the system energy efficiency. In this paper, a frosting model based on Euler multi-phase flow proposed before is used to simulate the frost layer growth process on wavy fin-and-tube heat exchanger surfaces. The model predicts the frost layer and temperature distributions on the heat exchanger surfaces. The air flow pressure drops before and after frosting have been obtained. The results show that the frost layer is unevenly distributed and no frost appears on the fin surfaces in the tube wake region. Frost on the wavy fin-and-tube heat exchanger surfaces restricts the airflow and the pressure drop increases about 140% after 45 min frosting. The simulation results are in good agreement with the experimental results.

This report presents the results of experimental and theoretical research of aerodynamics and convective heat transfer in cyclone devices with the new system of external recirculation of heating gas under the influence of radial pressure gradient in a heat carrier's swirling turbulent flow. The dynamic problem of tangential velocity distribution in a clearance volume is solved at various re-circulation ratio values including limiting quantities (k_r = 0; 1) and variations in cyclonic combustion chamber's design parameters and operating conditions (Re_r); the integrated calculation ratios for fundamental aerodynamic characteristics of a recirculation device are derived. The first experimental and numerical studies of convective heat transfer on internal and external surfaces of a hollow shaft in a swirling recirculation flow are derived through the instrumentality of OpenFOAM, these studies are also conducted for a setting of several cylindrical solid inserts. The external surface heat problem of a hollow cylindrical insert is solved with integral and digital methods; generalized similarity equations for the internal and external surfaces extended in range of Reynolds number are derived. The experimental data is in reasonable agreement with the derived curves and the results of mathematic modelling of convective heat transfer. Calculation recommendations for optimal selection of k_r values at various ratios of their geometric characteristics and products utilization rate are obtained.

The effect of precessing air flow on the processes of mixture formation in the wake of the front winding devices of the combustion chambers is considered. Visual observations have shown that at different times the shape of the atomized jet is highly variable and has signs of precessing motion. The experimental data on the distribution of the velocity and concentration fields of the droplet fuel in the working volume of the flame tube of a typical combustion chamber are obtained. The method of calculating flows consisted in integrating the complete system of Reynolds equations written in Euler variables and closed with the two-parameter model of turbulence k-ε. Calculation of the concentration fields of droplet and vapor fuel is based on the use of models for disintegration into droplets of fuel jets, fragmentation of droplets and analysis of motion and evaporation of individual droplets in the air flow. Comparison of the calculation results with experimental data showed their good agreement.

The pulsating flow in a circular channel with semicircular annular ribs as discrete roughness elements has been studied experimentally. Air flow under atmospheric conditions at the channel inlet has been considered. Steady and pulsating air flow has been studied under different frequencies and amplitudes of forced pulsations generated by periodic blockage of the channel cross section by a rotating flap. Flow resistance in pulsating regimes has been estimated from the average static pressure drop. The resistance values attained twice the steady flow ones.

The study of free-convective processes is important because of the cooling problem in many machines and systems, where other ways of cooling are impossible or impractical. Natural convective processes are common in the steam turbine air condensers of electric power plants located within the city limits, in dry cooling towers of circulating water systems, in condensers cooled by air and water, in radiators cooling oil of power electric transformers, in emergency cooling systems of nuclear reactors, in solar power, as well as in air-cooling of power semiconductor energy converters. All this makes actual the synthesis of the results of theoretical and experimental research of free convection for heat exchangers with finned tube bundles. The results of the study of free-convection heat transfer for two-, three- and four-row staggered horizontal bundles of industrial bimetallic finned tubes with finning factor of 16.8 and equilateral tubes arrangement are presented. Cross and diagonal steps in the bundles are the same: 58; 61; 64; 70; 76; 86; 100 mm, which corresponds to the relative steps: 1.042; 1.096; 1.152; 1.258; 1.366; 1.545; 1.797. These steps are standardized for air coolers. An equation for calculating the free-convection heat transfer, taking into account the influence of geometrical parameters in the range of Rayleigh number from 30,000 to 350,000 with an average deviation of ± 4.8%, has been obtained. The relationship presented in the article allows designing a wide range of air coolers for various applications, working in the free convection modes.

"Speeding up" heating (so called "piston-effect") of a closed domain of supercritical fluid is studied using 1D Navier-Stokes equations and van der Waals equation of state. Time dependences of temperature, density, pressure and velocity distributions are calculated for various initial conditions on temperature, density and gravity. It is shown that for some threshold value ε of the distance from critical point density stratification caused by gravity does not affect the characteristic time of the piston-effect τ_PE. The time τ_PE rises more rapid as a function of characteristic density μ when fluid has the step temperature-density stratification in comparison with that for the homogeneous density. The results are compared with the analytical solutions obtained by Onuki.

The results of experimental studies of industrial furnace with a fluidized bed reactor. The data on the values of the coefficient of heat transfer, the quality of fluidization and mixing efficiency. In theory shows that there are significant variables of temperature gradients on the walls of the heat exchange elements are qualitative arguments about the causes of increased wear of heat exchange surfaces in a fluidized bed.

The structure of the electrovortex flow appearing when the electric current passing through the liquid metal interacts with own and external magnetic fields was investigated numerically. It was shown that axial external magnetic field leads to the rotation of the liquid and generates secondary flow similar to Taylor vortex. Calculations were carried out for various ratios of electrode sizes.

The flow generated in the conductive medium with the electromagnetic force appearing when non-uniform electric current interacts with the own magnetic field was considered. The problem was solved analytically using Stokes approximation in a hemispherical geometry. Also numerical solution was obtained and comparing with the oldest mode of analytical one was carried out. The numerical and asymptotic results are quite similar.

The compatibility of the semiempirical turbulence theory of L. Prandtl with the actual flow pattern in a turbulent boundary layer is considered in this article, and the final calculation results of the boundary layer is analyzed based on the mentioned theory. It shows that accepted additional conditions and relationships, which integrate the differential equation of L. Prandtl, associating the turbulent stresses in the boundary layer with the transverse velocity gradient, are fulfilled only in the near-wall region where the mentioned equation loses meaning and are inconsistent with the physical meaning on the main part of integration. It is noted that an introduced concept about the presence of a laminar sublayer between the wall and the turbulent boundary layer is the way of making of a physical meaning to the logarithmic velocity profile, and can be defined as adjustment of the actual flow to the formula that is inconsistent with the actual boundary conditions. It shows that coincidence of the experimental data with the actual logarithmic profile is obtained as a result of the use of not particular physical value, as an argument, but function of this value.

Research results of "k-ε" turbulence integral model (TIM) parameters dependence on the angle of a coolant flow in regular smooth cylindrical rod-bundle are presented. TIM is intended for the definition of efficient impulse and heat transport coefficients in the averaged equations of a heat and mass transfer in the regular rod structures in an anisotropic porous media approximation. The TIM equations are received by volume-averaging of the "k-ε" turbulence model equations on periodic cell of rod-bundle. The water flow across rod-bundle under angles from 15 to 75 degrees was simulated by means of an ANSYS CFX code. Dependence of the TIM parameters on flow angle was as a result received.

Numerical procedure of modelling interaction between dielectric barrier discharge and duct flow based on RANS equations has been developed and tested in present study. Qualitative and approximate quantitative correspondence between known experimental data and numerical results has been achieved. Typical volume force and heat magnitudes has been evaluated, these values could be used as estimation in steady approximation calculations. DBD actuator model has shown up that required volume force magnitude has to be increased by 2-3 orders to influence on flow separation in S-type engine ducts at relatively high inlet velocity. Different method of volume force calculation using actuator operating parameters (Single Potential Method and Dual Potential Method) has been carried out. Continuous volume force components fields have been calculated as a function of DBD actuator applied voltage and surface charge density amplitude.

A scheme of an experimental setup for generation and control of sinusoidal pulsatile channel flow has been presented. A pulsator with the shaped rotating flap ensured a cross section area variation by harmonic law is used. Based on the solution of Bernoulli's unsteady equation and the numerical solution of the URANS equations, the effect of inertia forces on the law of average velocity variation over the pulsation phase in the test section of the experimental setup has been estimated.

Velocity distribution in the zone of developed wall turbulence, regardless of the conditions on the wall, is described by the well-known Prandtl logarithmic profile. In this distribution, the constant, that determines the value of the velocity, is determined by the nature of the interaction of the flow with the wall and depends on the viscosity of the fluid, the dynamic velocity, and the parameters of the wall roughness.In extreme cases depending on the ratio between the thickness of the viscous sublayer and the size of the roughness the constant takes on a value that does not depend on viscosity, or leads to a ratio for a smooth wall.It is essential that this logarithmic profile is the result not only of the Prandtl theory, but can be derived from general considerations of the theory of dimensions, and also follows from the condition of local equilibrium of generation and dissipation of turbulent energy in the wall area. This allows us to consider the profile as a universal law of velocity distribution in the wall area of a turbulent flow.The profile approximation up to the maximum speed line with subsequent integration makes possible to obtain the resistance law for channels of simple shape. For channels of complex shape with rough walls, the universal profile can be used to formulate the boundary condition when applied to the calculation of turbulence models.This paper presents an empirical model for determining the constant of the universal logarithmic profile. The zone of roughness is described by a set of parameters and is considered as a porous structure with variable porosity.

Using a differential turbulence model, a numerical simulation of turbulent flow in a tube is carried out and the dependences of the flow and heat transfer characteristics on the intensity of the coolant injection through permeable walls are obtained. It is shown that the coefficients of friction and heat transfer decrease with increasing of injection rate. The comparison of calculation results reflecting the main features of rather complicated processes of flow in tube under gas injection with well-known experimental data over a wide range of the Reynolds number and the intensity of injection show their satisfactory agreement.

According to the current calculation recommendations for turbulent flow, coefficient of hydraulic resistance of a smooth annular channel with an equivalent hydraulic diameter dh is assumed to be equal to the coefficient of hydraulic resistance of a pipe with a diameter dh multiplied by a conversion factor. The value of this conversion factor, depending on the Reynolds number and the ratio of the inner diameter of the annular channel to the outer diameter, varies from 1 to 1.07. That is, a smooth annular channel and a smooth pipe with the same hydraulic diameters have practically the same hydraulic resistance coefficients. In this paper, experiments were conducted to test the feasibility of such an approach to channels with rough walls. According to measurements of water flow and pressure gradient, the coefficients of hydraulic resistance of a rough annular channel and a pipe with hydraulic diameters d_h = 6 mm were calculated and compared. A trapezoidal artificial roughness was applied to the surfaces, which are flowing with a liquid. The experiments were carried out on a water circuit in the Reynolds number range from 10³ to 10⁵ in the regime of full roughness. The obtained experimental results were compared with calculations of coefficients of hydraulic resistance of pipes with artificial roughness according to the existing recommendations. Conclusions are drawn on the possibility of determining the hydraulic resistance of rough annular channels through the resistance of rough pipes.

There are presented some results of computational-theoretical research on identifying thermo-physical features and topology of high-velocity curved and swirl flows, which are occur inside complicated channels of collector systems, active zones and nuclear power installations equipment with pressurized water reactors. Cylindrical curved channels of different configurations and various combinations of bends and cross sectional areas were considered as modeling objects. Results of computational experiments to determine velocity, pressure, vorticity and temperature fields in transverse and longitudinal sections of the pipeline showed that the complicated geometry of the channels can cause to large-scale swirl of flow, cavitation effects and generation acoustic fluctuations with wide spectrum of sound frequencies for the coolant in the dynamic modes.

The maximum wall temperature of a cooling channel of a nuclear reactor is one of the factors that affects directly of the safety and reliability of the nuclear reactor. In this paper suggested an equation, which allows calculating the maximum wall temperature of the cooling channel of the nuclear reactor with heat transfer enhancer installed, without enormous calculations.

Heat transfer in a laminar pulsating flow in rectangular channels with different ratios of the side lengths γ was simulated numerically by the method of finite differences for two kinds of the boundary conditions on the wall: the first and the second kind. The maximum ratio of the Nusselt number to its steady-state value near the entrance to the heated portion of the channel was calculated at high amplitude of pulsations. An increase in this ratio in the regime of stabilized heat transfer is explained. The reasons for differences in the dependence of the thermal values on the regime parameters (γ, dimensionless oscillation frequency, the Prandtl number) for the two considered boundary conditions are analysed.

Continuous casting of cylindrical ingots from aluminum and preparation of aluminum-based alloys and composites require intensive mixing of liquid metal phase in the crystallization area of the melt. It is evident that the topology of the flow in the liquid phase of an ingot should influence the processes occurring during crystallization. Contemporary continuous casting machines use MHD-stirrers that generate an azimuthal motion in a crystallizer with a warm top of circular cross-section in the presence of rotating magnetic field. The flow of metal in the liquid phase of an ingot is similar to its rotation in a solid state, and transport processes are most intensively carried out in the near near-wall region and near the ingot solidification front, where shear flows are essential. In this work, we consider the possibility of amplifying transport processes in the entire volume of a stirred metal by making the cross-section shape of the warm top of the crystallizer different from a circle. It has been found numerically that the total energy of the flow in a crucible of square cross-section is twice as lower as that in a crucible with circular cross-section at the same inductor current. Turbulent pulsations in the square crucible, as well as in the circular one, are concentrated mainly in the near-wall region. The energy of pulsations in the square crucible also reduces, but the time of stirring of the passive impurity introduced into the volume of the metal is less than in the circular crucible. The effect of MHD stirring on the vertical temperature distribution on the square crucible is higher than in the "round crucible".

In some DEMO blanket designs liquid metal flows in vertical ducts of rectangular cross-section between ceramic breeder units providing their cooling. Heat exchange in these conditions is governed by the influence of magnetic field (coplanar) and by buoyancy effects that depend on the flow orientation to the gravity vector (downward and upward flow). Magnetohydrodynamic and heat transfer of liquid metal in vertical rectangular ducts is not well researched. Experimental study of buoyancy effects in rectangular duct with coplanar magnetic field for one-sided heat load and downward and upward flowsis presented in this paper. The detail research with has been done on mercury MHD close loop with using of the probe technique allow to discover several advantageous and disadvantageous effects. The intensive impact of buoyancy force has been observed in a few regime of downward flow which has been laminarized by magnetic field. Due to the development in the flow of the secondary large-scale vortices heat transfer improved and the temperature fluctuations of the abnormally high intensity have been fixed. On the contrary, in the upward flow the buoyancy force stabilized the flow which lead to decreasing of the turbulence heat transfer ratio and, consequently, deterioration of heat transfer.

The research of hydrodynamics and heat transfer at the liquid metal (LM) downward flow and upflow in a vertical duct of a rectangular cross section with a ratio of sides ∼1/3 in a coplanar magnetic field (MF) under conditions of bilateral symmetrical heating is performed. The problem simulates the LM flow in the heat exchange channels for cooling the liquid metal module of the blanket of the thermonuclear reactor (TNR) of the TOKAMAK type. The experiments were carried out on the basis of the mercury magnetohydrodynamic test-bed (MHD) Moscow Power Engineering Institute (MPEI) – Joint Institute for High Temperatures of the Russian Academy of Sciences (JIHT RAS). The probe measurement technique was used in the flow. Profiles of averaged velocity and averaged temperature, as well as profiles of temperature pulsations in the axial planes of the channel cross-section, are obtained; the distribution of the dimensionless wall temperature along the perimeter unfolding of the channel in the section and along the length of the channel. A significant effect of thermogravitational convection (TGC), which leads to unexpected effects, is found. At the downflow in a magnetic field, in some modes, low-frequency pulsations of anomalously high intensity occur.

The direct numerical simulation (DNS) of MHD-heat transfer problems in turbulent flow of liquid metal (LM) in a horizontal pipe with a joint effect of the longitudinal magnetic field (MF) and thermo-gravitational convection (TGC). The authors calculated the effect of TGC in a strong longitudinal MF for a homogeneous heating. Investigated the averaged fields of velocity and temperature, heat transfer characteristics, the distribution of wall temperature along the perimeter of the cross section of the pipe. The effect of TGC on the velocity field is affected stronger than in the temperature field.

Turbulent convection of liquid sodium in a cylindrical cell, heated at one end face and cooled at the other, inclined to the vertical at angle 0 and π/4 is studied experimentally and numerically by solving the Oberbeck-Boussinesq equations with the LES (Large Eddy Simulation) approach for small-scale turbulence. The aspect ratio is one, i.e. cylinder length is equal to diameter L = D = 200 mm. The simulations were done using fixed heat flux thermal boundary conditions for the cylinder faces. To resolve the general problem of boundary condition in convective experiment with low Prandtl number liquids, a special kind of heat exchanger were designed for the experimental setup. Each heat exchanger is a temperature-controlled MHD (magnetohydrodynamic) stirrer, filled with sodium and separated from the convective cell by a thin copper plate. We demonstrate the efficiency of MHD stirring for the temperature control. In convective experiments the Rayleigh number, determined by the cylinder diameter, was in the range from 4.7 · 10⁶ to 1.7 · 10⁷. We show that the structure of the flow and the efficient heat transfer strongly depend on the inclination angle.

We introduce a hydrodynamic model of convective flows in a titanium reduction reactor. The reactor retort is a cylindrical vessel with a radius of 0.75 m and a height up to 4 m, filled with liquid magnesium at a temperature of 850°C. The exothermic chemical reaction on the metal surface, cooling of the side wall and heating of the lower part of the retort cause strong temperature gradients in the reactor during the process. These temperature gradients cause intensive convective flows inside the reactor. As a result of the reaction, a block of titanium sponge grows at the retort bottom and the magnesium salt, whose density is close to the density of magnesium, settles down. The process of magnesium salt settling in a titanium reduction reactor was numerically studied in a two-dimensional (full size model) and three-dimensional (30% size of the real model) non-stationary formulation. A detailed analysis was performed for configurations with and without presence of convective flow due to work of furnace heaters. It has been established that magnesium salt is settling in drops with sizes from ≈ 3 cm to ≈ 10 cm. It was shown that convective flow can entrain the drop and carry it with the vortex.

We performed feasibility analysis of 10 kW hydrogen backup power system (H2BS) consisting of a water electrolyzer, a metal hydride hydrogen storage and a fuel cell. Capital investments in H2BS are mostly determined by the costs of the PEM electrolyzer, the fuel cell and solid state hydrogen storage materials, for single unit or small series manufacture the cost of AB5-type intermetallic compound can reach 50% of total system cost. Today the capital investments in H2BS are 3 times higher than in conventional lead-acid system of the same capacity. Wide distribution of fuel cell hydrogen vehicles, development of hydrogen infrastructure, and mass production of hydrogen power systems will for sure lower capital investments in fuel cell backup power. Operational expenditures for H2BS is only 15% from the expenditures for lead acid systems, and after 4-5 years of exploitation the total cost of ownership will become lower than for batteries.

One- and two-dimensional mathematical models of the devices for the machine-free energy separation of compressible gas flows have been considered. The device is a "pipe in a pipe" heat exchanger; the supersonic flow passes along an internal cylindrical channel, the subsonic flow — along an external annular channel. Energy separation takes place without any moving pieces. Main stream divides in two parts: a cold one (subsonic) and a hot one (supersonic).

The proposed models were validated in a wide range of input parameters changes.

The influence of a direct and counter flow pattern at the energy separation effect was investigated in terms of subsonic cooling maximization. By using the developed models, the optimal profiles of the supersonic channel were determined from the maximum energy separation effect point of view at identical initial total pressures, total temperatures and mass flows.

The process of energy (temperature) separation in an airflow is experimentally investigated in a device consisting of two coaxial channels with heat-conducting walls. The air flows at a supersonic velocity along the inner channel and at a subsonic velocity in the outer channel. The initial total temperatures of the flows are the same. Heat transfer arises due to the energy separation effect in the boundary layer of the compressible flow with Prandtl number is not equal to unity. The parameters varied in the process of investigation are the initial flow temperature, the supersonic flow velocity (Mach number), the mass fraction of the subsonic flow, the scheme of the flow organization in the device, and the presence/absence of heat transfer intensifiers in the subsonic channel. In all the regimes considered the subsonic flow cooling and the supersonic flow heating were fixed. The total pressure of the subsonic flow was almost conserved in the maximum cooling regimes. The flow parameters that have an effect on the temperature separation efficiency are determined.

Experimental results for artificially initiated shock wave influence on machineless gas flow energy separation effect are presented. The working principle of the technique is based on interaction of supersonic and subsonic flows through the heat-conducting wall. In result at output there are two flows with different temperature – heated supersonic air flow and cooled subsonic one. Shock waves were initiated by conic ribs placed along the supersonic channel. During the research varied parameters included uni-flow and counter-flow air moving direction in subsonic and supersonic channels, subsonic flow rate divided by supersonic one (from 0 to 0.9), stagnation flow temperature (298, 313 and 343K) and initial Mach number (1.9, 2.5). The research was carried out with the use of infrared thermal imaging, thermocouples, total and static pressure probes, National Instruments automation equipment. Energy separation effect is increasing with the growth of Mach number and stagnation flow temperature. Rib placement in supersonic channel causes rise of static pressure and wall temperature and results in decreasing of energy separation effect at output of the device by less than 12%. Operability of the device with shock wave generation is remained.

The paper presents the results of an experimental and numerical study of the structure of a plume formed over a heated disk under conditions of conjugate heat transfer in a wide range of Grashof number. The data on the temperature field in the plume is compared with the visualization patterns. Numerical simulation was performed using the Ansys Fluent code, where the problem of the flow of a compressible gas in conditions of conjugate heat transfer in an unsteady formulation was solved under the assumption of laminar flow regime. As a result of a comparison of the results of physical and numerical experiments, there is a conclusion about a good qualitative concurrence of the flow structure. The heat transfer characteristics were studied experimentally and numerically: the local heat transfer coefficient, the heat flow from the heated disk, and the local and average Nusselt numbers. It is shown that the establishment of a periodic flow regime leads to a violation of the monotonicity of the distribution of the local heat transfer coefficient. In general, the data is in satisfactory agreement with the results of known works.

During recent experimental research a phenomenon of vortex reconnection between coils of helical-like vortex in expanding cone was revealed. Two different scenarios of the reconnection were recorded with high speed video camera. In one case a vortex ring linked with the main helical-like vortex was observed. In another case the vortex ring was found to separate from the main vortex. After separation the vortex ring moves by spiral trajectory approaching the channel wall. The subsequent experiments with synchronization of the video recording with measurements of the pressure on the channel wall revealed intense pressure pulses as the vortex ring passed near the probe. In the present work we develop an analytical model for describing the pressure pulses arising when the vortex ring passes along surface. For simplicity we consider a flat surface rather than a conical one. The performed analysis yielded the pressure distributions on the surface in dependence on the specified parameters. The most important parameter that determines the form of pressure peaks is the minimum distance from the vortex to the surface. Variation of the angles of inclination of the ring plane provides fundamentally different pulse shapes.

Paper presents the current results of work conducted by a joint research group of MPEI–JIHT RAS for experimental study of liquid metals heat transfer. The team of specialists of MPEI–JIHT RAS put into operation a new mercury MHD facility RK-3. The main components of this stand are: a unique electromagnet, created by specialists of the Budker Institute of Nuclear Physics (BINP), and a sealed liquid-metal circuit. The facility will be explored lifting and standpipe flow of liquid metal in a transverse magnetic field in channels of different forms. For the experiments on the study of heat transfer and hydrodynamics of flows for measuring characteristics such as temperature, speed, pulse characteristics, probe method is used. Presents the first experimental results obtained for a pipe in a transverse magnetic field. During the experiments with various flow parameters data was obtained and processed with constructing temperature fields, dimensionless wall temperature distributions and heat transfer coefficients along the perimeter of the work area. Modes with low frequency pulsations of temperature were discovered. The boundaries where low frequency temperature fluctuations occur were defined in a circular tube.

This article is devoted to the issues of simulation and calculation of thermal processes in the system called "Human body – Thermal protection - Environment" under low temperature conditions. It considers internal heat sources and convective heat transfer between calculated elements. Overall this is important for the Heat Transfer Theory. The article introduces complex heat transfer calculation method and local thermophysical parameters calculation method in the system called «Human body – Thermal protection – Environment», considering passive and active thermal protections, thermophysical and geometric properties of calculated elements in a wide range of environmental parameters (water, air). It also includes research on the influence that thermal resistance of modern materials, used in special protective clothes development, has on heat transfer in the system "Human body – Thermal protection – Environment". Analysis of the obtained results allows adding of the computer research data to experiments and optimizing of individual life-support system elements, which are intended to protect human body from exposure to external factors.

The present work contains the results of an experimental research of the flow characteristics and the mechanism occurring in flat passages during liquid flow around of various figures and by formation of the enhanced turbulence stream at the input aimed at improvement of fuel preparation for combustion. Below are implementation ways of non-linear wave mechanics effects and border layer turbulence intensification for formation of finely dispersed emulsions and components of liquid compounds that are non-soluble in each other providing for improvement of technological processes of common and alternative energy fuels preparation for combustion. It is shown that effects of acquiring finely dispersed fuel-water emulsions (high quality energy fuel based on either common or alternative products) are achieved at flow of liquids in shaped passages in a wide range of Re numbers with high pressure falls in a generator with different cavitation booster figures and various arrangement with topping area containing holes in front of cavity zones formation area.

The intensity of the hydrogen sources arriving from the third contour of installation in second in comparison with the hydrogen sources on NPP BN-600 increases by two – three order at using of high-temperature nuclear power plants with the sodium coolant (HT-NPP) for drawing of hydrogen and other innovative applications (gasification and a liquefaction of coal, profound oil refining, transformation of biomass to liquid fuel, in the chemical industry, metallurgy, the food-processing industry etc.). For these conditions basic new technological solutions are offered. The main condition of their implementation is raise of hydrogen concentration in the sodium coolant on two – three order in comparison with the modern NPP, in a combination to hydrogen removal from sodium and its pumping out through membranes from vanadium or niobium. The researches with use diffusive model have shown possibility to expel a casium inflow in sodium through a leakproof shell of fuel rods if vary such parameters as a material of fuel rods shell, its thickness and maintenance time at design of fuel rods for high-temperature NPP. However maintenance of high-temperature NPP in the presence of casium in sodium is inevitable at loss of leakproof of a fuel rods shell. In these conditions for minimisation of casium diffusion in structural materials it is necessary to provide deep clearing of sodium from cesium.

This paper presents the results of modeling of fully developed turbulent gas flow in a uniform heated vertical tube by using the LES method and Smagorinski model. Unstructured Cartesian grids with local anisotropic refinement were used for modeling hydrodynamics and heat transfer in cylindrical pipes. Such meshes unlike structured meshes in cylindrical coordinates allow to construct more detailed meshes for the LES method. In addition, such meshes allow to simulate flows in channels of arbitrary cross-section. To verify the proposed methodology the results of direct numerical simulation of turbulent air flow in a vertical heated tube for forced and mixed convection were used. Thus, for upward flows the most interesting case with significant laminarization flow due to the buoyancy influence was studied.

In this paper we describe PIV-system specially designed for the study of the hydrophysical processes in large-scale benchmark setup of promising fast reactor. The system allows the PIV-measurements for the conditions of complicated configuration of the reactor benchmark, reflections and distortions section of the laser sheet, blackout, in the closed volume. The use of filtering techniques and method of masks images enabled us to reduce the number of incorrect measurement of flow velocity vectors by an order. The method of conversion of image coordinates and velocity field in the reference model of the reactor using a virtual 3D simulation targets, without loss of accuracy in comparison with a method of using physical objects in filming area was released. The results of measurements of velocity fields in various modes, both stationary (workers), as well as in non-stationary (emergency).

The aim of study is research of features of convective heat transfer in relatively long cyclone chamber. The research of heat exchange was carried out in a wide range of Reynolds numbers using gradient heat flow sensors. In the experiments, the value of the entrance area was changed by the flow and the diameter of the outlet. The results obtained were presented in the form of similarity equation. It was proposed to use the possibilities of gradient thermometry for studying the processes of heat exchange in cyclone chambers.

The main problematic aspects of the reproduction and transmission of a unit of temperature by a direct method are considered. The methodology and hardware for its implementation are considered. An estimate of the expected uncertainty in the measurement of the thermodynamic temperature is given.

Temporally and spatially resolved 2D measurements are important for the studies of complex turbulent flows. The recently developed SIV technique (Smoke Image Velocimetry), which is superior to PIV in some cases, can be used for this purpose. SIV validation results are presented for the steady turbulent backward-facing step flow measurements. Velocity profiles and Reynolds stress profiles are given for the regions of oncoming flow, reverse flow, flow reattachment and relaxation. The Reynolds number based on the step height and oncoming flow velocity at the boundary layer edge was Re_h = 4834. The obtained data have been compared to LDA measurements and DNS.

The results of an experimental evaluation of the third-order moments profiles of velocity fluctuations and their partial derivatives in a zero pressure-gradient turbulent boundary layer are presented. Profiles of characteristics are estimated on the basis of the dynamics of two-component instantaneous velocity vector fields measured by the optical method Smoke Image Velocimetry (SIV). Comparison SIV-measurements with the results of measurements by a thermoanemometer and DNS data with similar Re_θ and Re_τ showed good agreement between the profiles of <u^'2v^'>⁺, <u^'v^'2>⁺, ∂<u^'2v^'>⁺/∂y⁺ и ∂<u^'v^'2>⁺/∂y⁺ obtained by SIV and DNS.

The results of the experimental estimating of the velocity profiles and turbulent pulsations in the boundary layer for adverse and favorable pressure gradients are presented. The profiles of characteristics based on the dynamics of two-component instantaneous velocity vector fields measured by the field optical method of Smoke Image Velocimetry are estimated. The measurements are performed with a large spatial and temporal resolution, the measurement results are relevant for estimating the terms of the conservation equation of turbulent energy in the boundary layer and for improving semiempirical turbulence models.

The main difference between Smoke Image Velocimetry (SIV) technique and the conventional PIV is that higher concentration of tracer particles typical of smoke visualization techniques is used in SIV. Not separate particles but smoke structures with continuous pixel intensity are visible in the recorded images. Owing to better smoke reflectivity, higher spatial and temporal resolution is obtained in the case when relatively simple equipment (camera and laser) is used. It is simple enough to perform SIV measurements of velocity vector field dynamics at the frequency exceeding 15000 Hz, which offers new opportunities in unsteady flow examination. The paper describes fundamentals of SIV technique and gives some new results obtained using this method for the measurements that require high spatial and temporal resolution. The latter include frequency spectra of turbulent velocity fluctuations, turbulence dissipation profiles in the boundary layer and higher-order moments of velocity fluctuations. It has been shown that SIV technique considerably extends the potential of experimental studies of turbulence and flow structure in high-speed processes.

For the first time is proposed to combine heat flux measurements with thermal imaging and PIV (particle image velocimetry) for a comprehensive study of flow and heat transfer at the surface of the circular cooling fin. The investigated hollow fin is heated from within with saturated water steam; meanwhile the isothermal external surface simulates one of the perfect fin. Flow and heat transfer at the surface of the solid fin of the same size and shape, made of titanium alloy is investigated in the same regimes. Gradient Heat Flux Sensors (GHFS) were installed at different places of the fin surface. Velocity field around a cylinder, temperature field at the surface of the fin and heat flux for each rated time were obtained. Comprehensive method including heat flux measurement, PIV and thermal imaging allow to study flow and heat transfer at the surface of the fin in real time regime. The possibility to study flow and heat transfer for non-isothermal fins is shown; it is allow to improve traditional calculation of the cooling fins.

The usage of gradient heat flux measurement for monitoring of heat flux on combustion chamber surface and optimization of diesel work process is proposed. Heterogeneous gradient heat flux sensors can be used at various regimes for an appreciable length of time. Fuel injection timing is set by the position of the maximum point on the angular heat flux diagram however, the value itself of the heat flux may not be considered. The development of such an approach can be productive for remote monitoring of work process in the cylinders of high-power marine engines.

This paper is devoted to investigation of possibilities of using the caustic method for determination of optical inhomogeneities parameters, which arise by heat and mass transfer processes. Conditions of the caustics appearance are considered for longitudinal probing of the diffusion layer of liquid by plane and cylindrical laser beams. Experimental visualization of dynamics of change in the caustics position is presented for various parameters of inhomogeneous media. New method for determination of surface temperature of a cooled body placed in transparent liquid is described.

In this paper, we present a technique for calculating the period of the interference pattern in the measuring volume of the laser Doppler anemometer, taking into account the change in the coordinate and the angle of intersection of the probing beams during measurements in a transparent inhomogeneous environment. Calculations of the error in determining the period of the interference pattern on the example of a rectangular channel model with a temperature Gaussian distribution (environment) are carried out, and the influence of the channel walls is also considered.

A new experimental-theoretical approach to the toxic gases concentrations assessment in case of fire indoors is offered. The analytical formulas for calculation of CO average volume density are received. These formulas do not contain the geometrical sizes of the room and surfaces dimensions of combustible materials and, therefore, are valid under conditions of as a small-scale fire as a large-scale fire. A small-scale experimental installation for modeling fire thermal and gas dynamics in the closed or open thermodynamic system has been designed. The results of the experiments on determining dependencies of CO average volume density from average volume temperature and oxygen average volume density as well as dependencies of specific coefficients of CO emission and specific mass rates of the combustible material gasification from the time of tests during the burning of wood, transformer oil and PVC cables shield are presented. The results of numerical experiments on CO density calculation in small and large scale rooms using the proposed analytical solutions, integral, zone and field models for calculation of fire thermal and gas dynamics are presented. The comparison with the experimental data obtained by the authors and given in the literature has been performed. It is shown that CO density calculation in the full-scale room at the incipient stage of the fire can be carried out taking into account only the experimental dependences of CO from temperature or O₂ density, that have been obtained from small-scale experiments. Therefore the solution of the equation of carbon monoxide mass conservation law is not necessary.

By using the heat balance equation and the modified Fourier's law formula, where the heat flux relaxation and temperature gradient were considered, the model of heat ignition non-equilibrium process for the plate with non-linear (exponentially changing depending on the temperature) inner heat source was developed. The studies performed at relaxed boundary third-class conditions have shown that consideration of non-locality results in the increased heat ignition time irrespective of the intensity of heat exchange with the ambient medium. This fact is explained by the resistance caused by the ambient medium, the process of change of its temperature condition which increases as the relaxation factors rise. It is also shown that with consideration of the relaxation phenomena boundary conditions of the first, second and third class may not be met immediately – they may be set only within a particular range of the initial time segment. This means that the immediate implementation of the thermal impact condition seems to be impossible, since the value of heat-transfer factor has a definite limit, which depends on the relaxation properties of the medium, which may not be exceeded under any conditions of heat exchange with the ambient medium.

High temperature chemical looping combustion is one of the promising technologies for CO₂ capture. The CLC reactor system consists of two principal reaction chambers: the air reactor (AR) and the fuel reactor (FR). High solid circulation rate between fuel and air reactors is very important for effective combustion of solid fuels in CLC. Some part of fuel ash particles is implemented in metal oxides flow. Thus, the circulation flux consists of heavy metal particles and light ash particles. Fluidization conditions of binary mixture of particles with different density and sizes are very important for CLC hydrodynamics. The investigation was made on cold model with interconnected reactors. The narrow fraction of Al₂O₃ with Sauter diameter 0.22 and 0.34 mm and density 3930 kg/m3 were used as bed materials. Silica sand with Sauter diameter 0.21 mm and density 2600 kg/m3 was a "coal ash". The investigations were made for mixture with volume fraction 50-95% of Al₂O₃. Small addition of sand gives a significant reduction of minimal fluidization velocity. There are a linear proportion between share of Al₂O₃ and pressure gradient. Some other phenomena were obtained in case of 0.34 mm Al₂O₃. Further investigations have aim to determine of light fraction addition on hydrodynamics of interconnected reactors.

The technology of low-temperature deaeration of water in thermal power plants was developed. It is proposed to use natural gas supplied to the furnace as desorbing agent in the deaerator instead steam or superheated water. Natural gas has low, often - negative temperature after reducing installs. At the same time, it contains virtually no corrosive gases, oxygen and carbon dioxide, thereby successfully may be used as a stripping agent in water deaeration. The calculation of the energy efficiency of the technology for a typical unit of CHP has shown that achieved a significant annual saving of fuel equivalent in the transition from the traditional method of deaeration of water in the low temperature deaeration. Hydrodynamic and mass transfer indicators were determined for the deaerator thermal power plants using as stripping medium natural gas supplied to the boiler burners. Theoretically required amount and the real specific consumption of natural gas were estimated for deaeration of water standard quality. The calculation of the hydrodynamic characteristics was presented for jet-bubbling atmospheric deaerator with undescended perforated plate when operating on natural gas. The calculation shows the possibility of using commercially available atmospheric deaerators for the application of the new low-temperature water deaeration technology.

In a three-dimensional formulation, an analytical solution of the Darcy-Brinkman equation is obtained together with the two-temperature Schumann model equations for the unidirectional flow of a Newtonian medium in a laminar regime through a horizontal porous channel of a constant rectangular cross-section with known thermal flows at the boundary for small Darcy numbers. The analysis of the specific structure of a compact porous heat exchanger is presented, where the possibilities of the obtained solution for justification its geometrical dimensions during the cooling process of the surface with a heat release of 100 W/cm² are demonstrated.

Numerical investigations of saline water flows in a horizontal porous layer resulted from water evaporation at the upper boundary and salt accumulation nearby are carried out. The mathematical model includes the continuity, Darcy's and contaminant transport equations. Over the threshold of saline profile stability, different regimes of haline convection in low- and high-permeable layers are simulated. As found, steady regular convection occupying a whole domain is induced in the case of weak evaporation. Stochastic convection with a small-scale structure of salt "drops" and salt precipitation are developed in the case of intensive evaporation. The maps of regimes are plotted and boundaries between regimes are determined.

Haline-convective flows of two-component fluids inside a porous rock are investigated numerically. Numerical simulations are based on the mathematical model which consists of the continuity, Darcy's and admixture transport equations. In a geothermal reservoir, the constant admixture concentration is held at the upper boundary leading to diffusive admixture transport into the volume. Near the upper boundary, fluid becomes denser and causes haline convection. Porous domains composed of layers at different properties are considered and their influence on haline-convective flows is investigated.

In chemically nonequilibrium flows the problem of calculation of sources (formation rates) in equations for chemical species is of utter importance. Formation rate of each component is a non-linear function of mixture density, temperature and concentration of species. Thus the suggestion that the mean rate may be determined via mean values of the flow parameters could lead to significant errors. One of the most accurate approaches here is utilization of probability density function (PDF). In this paper the method for constructing such PDFs is developed. The developed model was verified by comparison with the experimental data. On the example of supersonic combustion it was shown that while the overall effect on the averaged flow field is often negligible, the point of ignition can be considerably shifted up the flow.

In this paper a method for simulation of combustion of hydrogen in supersonic air flow is developed. Obtained results are in a good agreement with experimental data. A model hypersonic ramjet engine is considered at 35 km altitude at M=6 and different factors impacting on combustion are analyzed.

The paper presents a mathematical model of heat transfer developed for the purposes of modeling the operation process in large-scale vacuum furnaces. It has been implemented on the basis of the author's software complex "SigmaFlow".

Results of experimental research of low-temperature multicomponent mixed-refrigerant throttling refrigerator are given. Appliance of refrigerator in new domestic-made ultralow-temperature freezer for cryoconservation and long-term storage of medical and biological objects at temperature minus 150°C is described. Within experimental research, test bench with development prototype of ultralow-temperature medical freezer is made. Experimental and theoretical studies are compared. Availability and amount of local composition shift is defined. Ways to improve simulation model and increase energy efficiency of cryostatting systems are determined.

The thermodynamic analysis of the composition of the combustion products of 15 types of coals was carried out with consideration for the formation of potassium and sodium aluminosilicates and solid and liquid slag removal. Based on the results of the analysis, the approximating temperature dependences of the concentrations of condensed components (potassium and sodium sulfates) were obtained for the cases of two-phase and single-phase equilibriums; conclusions on the comparative influence of solid and liquid slag removal on the probability of the formation of submicron particles on the combustion of coals were made. The found dependences was make it possible to perform a numerical simulation of the bulk condensation of potassium and sodium sulfate vapors upon the cooling of coal combustion products in a process flow. The number concentration and size distribution of the formed particles have been determined. Agreement with experimental data on the fraction composition of particles has been reached at a reasonable value of a free parameter of the model.

The productivity of Fischer-Tropsch reactors is determined by the efficiency of heat and mass transfer processes inside the catalyst pellets. To reduce the diffusion resistance, the pellet base is made porous. The porous structure of the granules causes a discrete arrangement of cobalt metallic microparticles whose size can reach tens of microns. The distance between these active centres significantly exceeds their characteristic size and the homogeneous catalyst model is incorrect. A mathematical model of heat and mass transfer processes inside a porous spherical pellet with localised active centres is proposed. The heat of the exothermic synthesis reaction is removed from the surface of the granule to the synthesis gas stream washing the catalyst pellet by heat transfer. The components of the synthesis gas enter the granule surface as a result of mass transfer. On the basis of the self-consistent field method, the values of the temperature and concentration of the synthesis gas components at the active centres were determined. It is shown that there is a critical temperature of the synthesis gas washing the granule, exceeding critical temperature leads to a substantial overheating of the active centres. In this case, the surface of the catalyst pellet is superheated slightly. The principal difference between the homogeneous and heterogeneous models in catalytic reactions is discussed.

The physical processes underlying the perspective method of water extraction in anhydrous arid regions of the Earth are considered in the article. This method is based on the use of a porous, salty material that allows intensive absorption of moisture from the air, followed by evaporation of the formed brine with the help of sunlight and vapor deposition on the inner surface of the transparent solar plant cover. Based on the laws of the molecular-kinetic theory, the authors derive a general expression for the intensity of moisture trapping. Based on the expression obtained, it is concluded that to capture moisture, it is necessary to lower the density of saturated vapor over the porous surface in comparison with the density of the vapor being precipitated. Taking this into account two methods are considered: capillary condensation and salty solution. Considering both ways, their patterns and driving mechanisms, the authors conclude that the most effective way is the second one, and the first one can be considered as an auxiliary method. The article provides a detailed derivation of the conditions necessary to absorb moisture in the form of a brine and its evaporation when obtaining pure water. The material of the article can be useful in the design of solar installations.

Experimental study of the features of separation process in ternary gas mixtures 0.6179 H₂ + 0.3821 N₂ – CH₄ and 0.7760 CH₄ + 0.2240 R12 – n-C₄H₁₀ is conducted. Conditions of the priority transfer of the density heaviest component of the mixture are discussed. The problem is solved by the splitting scheme by physical parameters. Numerical data on the time evolution of components concentrations at different concentrations of components of the initial mixture are obtained. Calculations have shown that for ternary systems the concentration increase of the heaviest component results to the intensity growth of convective mixing.

A porous wet medium with solid and gaseous components, with distributed or localized heat sources was considered. The regimes of temperature changes at the heating at various initial material moisture were studied.

Mathematical model was developed applied to the investigated wet porous multicomponent medium with internal heat sources, taking into account the transfer of the heat by heat conductivity with variable thermal parameters and porosity, heat transfer by radiation, chemical reactions, drying and moistening of solids, heat and mass transfer of volatile products of chemical reactions by flows filtration, transfer of moisture.

The algorithm of numerical calculation and the computer program that implements the proposed mathematical model, allowing to study the dynamics of warming up at a local or distributed heat release, in particular the impact of the transfer of moisture in the medium on the temperature field were created.

Graphs of temperature change were obtained at different points of the graphics with different initial moisture. Conclusions about the possible control of the regimes of heating a solid porous body by the initial moisture distribution were made.

In the present work non-uniformities of microstructure, porosity and adsorption characteristics of La_0.9Ce_0.1Ni₅ metal hydride by the height of the bed are investigated. A 500 g metal hydride bed was cycled inside a vertical metal hydride reactor and three samples was taken from top, middle and bottom of the bed. Non-uniform particle distributions and bed densification were observed, the bed porosity is around 0.58-0.67 at the top and middle parts of the bed and 0.46-0.54 at the bottom, where a dense and robust agglomerate was formed during the cycling. Specific surface area measured by nitrogen adsorption methods is 1.8-2.1 m²/g at the top of the bed, 4.2-5.4 m²/g in the middle and 1.1-1.5 m²/g at the bottom. The maximum is connected with higher degree of particle dispersion without effects from particle agglomeration.

Results of numerical modeling of the coupled nonstationary heat and mass transfer problem under conditions of a convective flow in facade system of a three-layer concrete panel for two different constructions (with ventilation channels and without) are presented. The positive effect of ventilation channels on the energy and humidity regime over a period of 12 months is shown. Used new method of replacement a solid zone (requiring specification of porosity and material structure, what complicates process of convergence of the solution) on quasi-solid in form of a multicomponent mixture (with restrictions on convection and mass fractions).

A thermal analysis of a mixture of municipal solid waste (MSW) of the average morphological composition and its individual components was carried out in order to develop ways to improve the efficiency of its utilization for energy production in thermal reactors. Experimental studies were performed on a synchronous thermal analyzer NETZSCH STA 449 F3 Jupiter combined with a quadrupole mass spectrometer QMC 403. Based on the results of the experiments, the temperature ranges of the pyrolysis process were determined as well as the rate of decrease of the mass of the sample of solid waste during the drying and oxidative pyrolysis processes, the thermal effects accompanying these processes, as well as the composition and volumes of gases produced during oxidative pyrolysis of solid waste and its components in an atmosphere with oxygen content of 1%, 5%, and 10%. On the basis of experimental data the dependences of the yield of gas on the moisture content of MSW were obtained under different pyrolysis conditions under which a gas of various calorific values was produced.

The possibility of increasing the energy efficiency of production processes by converting the initial fuel – natural gas to synthesized fuel using the heat of the exhaust gases of plants involved in production is considered. Possible applications of this technology are given. A mathematical model of the processes of heat and mass transfer occurring in a thermochemical reactor is developed taking into account the nonequilibrium nature of the course of chemical reactions of fuel conversion. The possibility of using microchannel reaction elements and facilities for methane conversion in order to intensify the process and reduce the overall dimensions of plants is considered. The features of the course of heat and mass transfer processes under flow conditions in microchannel reaction elements are described. Additions have been made to the mathematical model, which makes it possible to use it for microchannel installations.

With the help of a mathematical model, distribution of the parameters of mixtures along the length of the reaction element of the reactor-temperature, the concentration of the reacting components, the velocity, and the values of the heat fluxes are obtained. The calculations take into account the change in the thermophysical properties of the mix-ture, the type of the catalytic element, the rate of the reactions, the heat exchange processes by radiation, and the lon-gitudinal heat transfer along the flow of the reacting mixture.

The reliability of the results of the application of the mathematical model is confirmed by their comparison with the experimental data obtained by Grasso G., Schaefer G., Schuurman Y., Mirodatos C., Kuznetsov V.V., Vitovsky O.V. on similar installations.

We perform cycling of a 500 g bed of La_0.9Ce_0.1Ni₅ intermetallic compound in vertical and horizontal orientations with measurements of PCT isotherms, and further XRD and SEM investigation of bed structure. Significant decrease in equilibrium absorption pressure is observed in vertical orientation of the bed from 1.58 to 1.36 MPa at 333K, and from 2.68 to 2.51 MPa at 353K, accompanied by evident particle segregation by the bed height and densification at a bottom with formation of a robust agglomerate of small particles (< 10 μm) jointed with big particles of the size 100-200 μm, while particle size distribution in upper parts is more uniform with mean size about 10-20 μm. Fill density increases by 15% from the top to the bottom from 3.26 g/cm³ to 3.86 g/cm³ while structural properties of particles remain the same with X-ray density 8.31 g/cm³. Investigations of heat and mass transfer inside a vertical metal hydride reactor RSP-8 with 1 kg of La_0.9Ce_0.1Ni₅ also show considerable non-uniformity of pressure inside the bed. If the reactor is charged from the top the hydrogen pressure at the bottom is lower on 0.2-0.3 MPa, which results in earlier occurrence of heat and mass transfer crisis.

Experts of LLC "New Energy Technologies" have developed gasifiers designs, with the implementation of the three-zone gasification method, which satisfy the following conditions: 1) the generated gas must be free from tar, soot and hydrocarbons, with a given ratio of CO/H2; 2) to use as the fuel source a wide range of low-grade low-value solid fuels, including biomass and various kinds of carbonaceous wastes; 3) have high reliability in operation, do not require qualified operating personnel, be relatively inexpensive to produce and use steam-air blowing instead of expensive steam-oxygen one; 4) the line of standard sizes should be sufficiently wide (with a single unit capacity of fuel from 1 to 50-70 MW). Two models of gas generators of the inverted gasification process with three combustion zones operating under pressure have been adopted for design: 1) gas generator with a remote combustion chamber type GOP-VKS (two-block version) and 2) a gas generator with a common combustion chamber of the GOP-OK type (single-block version), which is an almost ideal model for increasing the unit capacity.

There have been worked out various schemes for the preparation of briquettes from practically the entire spectrum of low-grade fuel: high-ash and high-moisture coals, peat and biomass, including all types of waste - solid household waste, crop, livestock, poultry, etc. In the gas generators there are gasified the cylindrical briquettes with a diameter of 20-25 mm and a length of 25-35 mm.

There have been developed a mathematical model and computer code for numerical simulation of synthesis gas generation processes in a gasifier of a dense layer of inverted process during a steam-air blast, including: continuity equations for the 8 gas phase components and for the solid phase; the equation of the heat balance for the entire heterogeneous system; the Darcy law equation (for porous media); equation of state for 8 components of the gas phase; equations for the rates of 3 gas-phase and 4 heterogeneous reactions; macro kinetics law of coke combustion; other equations and boundary conditions.

The paper presents the results of studies on the perspective technologies of natural gas conversion to synthetic liquid fuel (SLF) at energy-technology installations for combined production of SLF and electricity based on their detailed mathematical models. The technologies of the long-distance transport of energy of natural gas from large fields to final consumers are compared in terms of their efficiency.

The effect of pressure increase was observed in steam condensation in the intermediate coolers of multistage steam ejector. Steam pressure increase for ejector cooler amounts up to 1.5 kPa in the first ejector stage, 5 kPa in the second and 7 kPa in the third one. Pressure ratios are equal to 2.0, 1.3 and 1.1 respectively. As a rule steam velocities at the cooler inlets do not exceed 40...100 m/s and are subsonic in all regimes.

The report presents a computational model that describes the effect of pressure increase in the cooler. The steam entering the heat exchanger tears the drops from the condensate film flowing down vertical tubes. At the inlet of heat exchanger the steam flow capturing condensate droplets forms a steam-water mixture in which the sound velocity is significantly reduced. If the flow rate of steam-water mixture in heat exchanger is greater than the sound velocity, there occurs a pressure shock in the wet steam.

On the basis of the equations of mass, momentum and energy conservation the authors derived the expressions for calculation of steam flow dryness degree before and after the shock. The model assumes that droplet velocity is close to the velocity of the steam phase (slipping is absent); drops do not come into thermal interaction with the steam phase; liquid phase specific volume compared to the volume of steam is neglected; pressure shock is calculated taking into account the gas-dynamic flow resistance of the tube bundle. It is also assumed that the temperature of steam after the shock is equal to the saturation temperature.

The calculations have shown that the rise of steam pressure and temperature in the shock results in dryness degree increase. For calculated flow parameters the velocity value before the shock is greater than the sound velocity. Thus, on the basis of generally accepted physics knowledge the computational model has been formulated for the effect of steam pressure rise in the condensing heat exchanger.

The results of experimental studies of the process of condensate microdroplets centering contained in the moving moist vapour in the vapour channel of short heat pipes (HPs) for large thermal loads are presented. A vapour channel formed by capillary-porous insert in the form of the inner Laval-liked nozzle along the entire length of the HP. In the upper cover forming a condensation surface in the HP, on the diametrical line are installed capacitive sensors, forming three capacitors located at different distances from the longitudinal axis of the vapour channel. With increasing heat load and the boil beginning in the evaporator a large amount of moist vapour in the vapour channel of HP occur the pressure pulsation with frequency of 400-500 Hz and amplitude up to 1·10⁴Pa. These pulsations affect the moving of the inertial droplets subsystem of the vapour and due to the heterogeneity of the velocity profile around the particle flow in the vapour channel at the diameter of microdroplets occurs transverse force, called the Saffman force and shear microdroplets to the center of vapour channel. Using installed in the top cover capacitors we can record the radial displacement of the condensable microdroplets.

In the present study experimental heat transfer data on condensation of almost immobile water-ethanol and water-isopropanol vapor mixtures on the vertical smooth copper tube 100 mm long with an outer diameter of 12.0 mm were obtained. Experiments for water-ethanol mixture were carried out at mass concentrations of ethanol from 0.4 to 16% in the vapor phase, and for a water-isopropanol mixture - from 0.6 to 8.4%. The pressure was 0.12...0.13 MPa, vapor-to-surface temperature difference varied from 2 to 40K. The experimental data are represented as dependency of heat transfer coefficient and heat flux on the vapor-to-surface temperature difference. The results of high-speed photography of the condensation process are discussed. It is noted that the transition from film mode to pseudo-dropwise condensation occurs when vapor-to-surface temperature difference is close to dew point - bubble point temperature difference for a given composition of the mixture. According to experimental data, the diffusion thermal resistance and thermal resistance of the liquid phase at different concentrations of the mixture were calculated.

A theoretical model for calculation of heat transfer during condensation of multicomponent vapor-gas mixtures on vertical surfaces, based on film theory and heat and mass transfer analogy is proposed. Calculations were performed for the conditions implemented in experimental studies of heat transfer during condensation of steam-gas mixtures in the passive safety systems of PWR-type reactors of different designs. Calculated values of heat transfer coefficients for condensation of steam-air, steam-air-helium and steam-air-hydrogen mixtures at pressures of 0.2 to 0.6 MPa and of steam-nitrogen mixture at the pressures of 0.4 to 2.6 MPa were obtained. The composition of mixtures and vapor-to-surface temperature difference were varied within wide limits. Tube length ranged from 0.65 to 9.79m. The condensation of all steam-gas mixtures took place in a laminar-wave flow mode of condensate film and turbulent free convection in the diffusion boundary layer. The heat transfer coefficients obtained by calculation using the proposed model are in good agreement with the considered experimental data for both the binary and ternary mixtures.

Membrane-type total heat exchanger (THX) is an air-to-air heat exchanger used to reduce the building energy consumption associated with forced ventilation by recovering both heat and moisture from ventilation air. It contains a heat/moisture exchange core made of a water vapour permeable membrane, supply outdoor air and exhaust indoor air flow through the membrane channels in the core in a crossflow manner and exchange heat and moisture across the membranes. The present work numerically investigates the airflow channel entrance effects on the THX performance. The results show that such effects on the air temperature and humidity distributions are inconspicuous and so are they on the THX effectiveness, it is therefore appropriate to use the constant Nusselt number to evaluate the THX performance.

The paper is devoted to research of the heat and mass transfer processes in liquid and vapor phase on the basis of the uniform approach assuming the through description of liquid, interface and vapor. Multiparticles interactions in liquid will be taken into account. The problem is studied when temperature in the depth of liquid differs from temperature in the vapor region. In this case there are both mass flux and heat flux. The study of influence of the correlations resulting from interactions of molecules set in thin near-surface liquid layers and an interface on intensity of evaporation is made. As a result of calculations the equilibrium line of the liquid-vapor saturation is obtained, which corresponds good enough with experimental data. Distributions of density, temperature, pressure, heat and mass fluxes, both in a liquid and in vapor are also presented.

The heat flux measurement is used for research of heat transfer during condensation of saturated water steam at the surface of the tube made of stainless steel. A number of produced experimental setups allowed us to set different directions of movement of steam and cooling water, to change the space orientation of the tube, and also rotate the tube around its axis. In addition, the places of installation of the gradient heat flux sensors at internal and external surfaces of the tube were ranged. In the experiments we determined the local heat transfer coefficients, and their change along the length of the tube and for different values of the azimuthal angle. The obtained data allow to study in detail the formation of the film of condensate on the inside and outside surfaces of the tube and the heat transfer. The experimental results is in accordance with the classical ideas. The graphs show the pulsations of heat flux, which enable us to investigate non-stationary parameters of heat transfer during condensation. Experimental results differ from those calculated according to the Nusselt's formula for 15% with standard uncertainty lower than 10%.

The process of bulk condensation was studied on a basis numerical solution of kinetic equation for the mass distribution function of droplet size and the equations of mass and energy balance. The effect of the condenser and preheater deference temperature was studied. Obtained results were compared with other authors' experimental and numerical data qualitatively and quantitatively.

A thermo mechanical aspect of the fragmentation of a liquid metal droplet, solidified as it falls into cold water, is considered in the presented model. The formation of a solid phase in the form of continuous, fluid-tight and relatively rigid casting skin results in a pressure decrease inside the droplet due to the difference between liquid and solid metal density. Because of the high compression modulus of the melt, the pressure in the droplet becomes negative when the thickness of the solid skin achieves several microns. The tensile stress in the melt results in the deformation of the casting skin or the melt's continuity violation in the form of a shrinkage pore. The rupture of the deformed solid crust results in the penetration of steam jets into the liquid part of the drop. Due to the difference in pressure in the surrounding steam and in the droplet, the casting skin is crushed and the melt is blown out. Both scenarios contribute to the hydrodynamic destruction of the droplet. The suggested thermo mechanical model gives a qualitative explanation for experimental data. In the experimental part of the work, droplets of molten Sn were solidified in water. The solidified pieces of the droplets usually include deformed, thin-walled shells and dispersed particles. On a qualitative level the composition and shape of the solid fragments can be explained within the bounds of the suggested thermo mechanical model.

The most generally useful methods for cleaning and processing of surfaces are the sand-jets and shot blasting jets. Installations of this kind are used for cleaning of corrosion surfaces, the oil-dirt deposits, paint coatings. However the use of these installations follows to high investment and operational expenditure, larger risk of operators disease, the negative affect for a environment. These problems can be solved with the use of new cleaning method through application of mono-disperse (identical by the size and the form) ice granules of 300 - 1000 microns, accelerated by air stream in the nozzle device to the speed of 10 - 100 m/s. In view of the extreme complexity of the receiving such particles by means of cooling and the subsequent freezing of water drops are necessary additional experimental researches. For study of thermal processes of receiving mono-disperse ice granules the experimental installation was created and experiments on deactivation and cleaning of surfaces with pollution of various types are made. Experiments showed that by means of a stream of the accelerated ice granules it is rather successfully possible to delete oil-dirt deposits, outdated paint coats and rust. Besides, efficient deactivation of radioactive surfaces is possible. The coefficient deactivation of γ activity is highest.

The basic possibility of creation of high speed cryogenic monodisperse targets is shown. According to calculations at input of thin liquid cryogenic jets with a velocity of bigger 100 m/s in vacuum the jets don't manage to freeze at distance to 1 mm and can be broken into monodisperse drops. Drops due to evaporation are cooled and become granules. High speed cryogenic monodisperse targets have the following advantages: direct input in vacuum (there is no need for a chamber of a triple point chamber and sluices), it is possible to use the equipment of a cluster target, it is possible to receive targets with a diameter of D < 20 μk from various cryogenic liquids (H2, D2, N2, Ar,...) with dispersion less than 1%, the high velocity of monodisperse granules(> 100m/s), exact synchronization of the target hitting moment in a beam with the moment of sensors turning on.

The report presents: the methodology of calculation of contact condensation of steam from the steam-gas mixture into the stream of water, taking into account: the mass flow of steam through the boundary phase, particularly the change in turbulent transport properties near the interface and their connection to the interface perturbations due to the surface tension of the mixture; the method of calculation of the surface tension at the interface water - a mixture of fluorocarbon vapor and water, based on the previously established analytical methods we calculate the surface tension for simple one - component liquid-vapor systems. The obtained analytical relation to calculate the surface tension of the mixture is a function of temperature and volume concentration of the fluorocarbon gas in the mixture and is true for all sizes of gas molecules. On the newly created experimental stand is made verification of experimental studies to determine the surface tension of pure substances: water, steam, C₃F₈ pair C₃F₈, produced the first experimental data on surface tension at the water - a mixture of water vapor and fluorocarbon C₃F₈. The obtained experimental data allow us to refine the values of the two constants used in the calculated model of the surface tension of the mixture. Experimental study of jet condensation was carried out with the flow in the zone of condensation of different gases. The condensation process was monitored by measurement of consumption of water flowing from the nozzle, and the formed condensate. When submitting C₃F₈, there was a noticeable, intensification condensation process compared with the condensation of pure water vapor. The calculation results are in satisfactory agreement with the experimental data on surface tension of the mixture and steam condensation from steam-gas mixture. Analysis of calculation results shows that the presence of surfactants in the condensation zone affects the partial vapor pressure on the interfacial surface, and the thermal conductivity of the liquid jet. The first circumstance leads to deterioration of the condensation process, the second to the intensification of this process. There is obviously an optimum value of concentration of the additive surfactants to the vapour when the condensation process is maximum. According to the developed design methodology contact condensation can evaluate these optimum conditions, their practical effect in the field study.

A mathematical model has been constructed that describes the deposition of material on a curvilinear surface. This model considers convective heat transfer, heat transfer by radiation, and heat and mass transfer during the attachment of the substance to the surface. For the model numerical algorithm is constructed to find the temperature profile in a curvilinear plate; results of calculations for different materials are given.

Using of heat-exchanger-condenser in the air conditioning system of the airplane Tu-204 (Boeing, Airbus, Superjet 100, MS-21, etc.) for cooling the compressed air by the cold air with negative temperature exiting the turbine results in a number of operational problems. Mainly it's frosting of the heat exchange surface, which is the cause of live-section channels frosting, resistance increasing and airflow in the system decreasing. The purpose of this work is to analyse the known freeze-up-fighting methods for heat-exchanger-condenser, description of the features of anti-icing protection and offering solutions to this problem. For the problem of optimizing the design of heat exchangers in this work used generalized criterion that describes the ratio of thermal resistances of cold and hot sections, which include: the ratio of the initial values of heat transfer agents flow state; heat exchange surface finning coefficients; factors which describes the ratio of operating parameters and finning area. By controlling the ratio of the thermal resistances can be obtained the desired temperature of the heat exchange surface, which would prevent freezing. The work presents the results of a numerical study of the effect of different combinations of regime and geometrical factors changes on reduction of the heat-exchanger-condenser freezing surface area, including using of variable ratio of thermal resistances.

In the present work experimental data on heat transfer are obtained for the condensation of almost immobile pure steam and water-ethanol vapor mixture on three copper horizontal finned tubes with a cooled length of 100 mm. The fins are rectangular in shape, their height and thickness are 1 mm, and the spacing between fins 1.3, 2.0 and 3.0 mm. The experiments were carried out at pressures of 0.12...0.15 MPa, the vapor-to-surface temperature difference varied from 5 to 35 K. The mass concentration of ethanol in the vapor phase varied from 8.7 to 14.5%. The experimental data are presented in the form of the dependences of heat transfer coefficient on the vapor-to-wall temperature difference. The heat transfer coefficients for the condensation of pure steam are in good agreement with the calculations by the method of Srinivasan et al. According to experimental data for the condensation of the vapor mixture, diffusion thermal resistance and thermal resistance of the liquid phase at various ethanol concentrations and the spacing between fins were calculated.

The paper deals with issues related to determining the value of the thermal resistance of the fin-wall contact in heat exchangers. The description of the process of heat transfer between heat carriers and the main factors and the key parameters which determine the thermal resistance between the rib and the wall is presented. The experimental stand for thermal-hydraulic studies of the tube bundle model was developed. A technique for estimating the thermal resistance of a rib-wall contact on the basis of experimental studies is proposed. An estimation of possible sources of errors that should be taken into account when performing calculations is carried out.

This paper presents the results of validation a model in which the flow of a vapour—air mixture is described by the Navier–Stokes equations for laminar regime or by the RANS equations for turbulent regime and the condensate film is considered using a one-dimensional model. The data available from the literature was employed to verify the proposed model for forced convection condensation with and without noncondensables. The numerical results are in good agreement with the literature experimental data. A description is presented of the details of the numerical implementation of the algorithm developed. The results of the addition test to validate the assumptions and simplifications used in the model are also presented.

In this work the studies of the hydraulic resistance and the heat transfer of tubes with inner helical finning over a wide range of the geometric and operating parameters are presented: Re_D=4·10³-2·10⁵ under the variation of the angle of swirling θ=14°-87°, the relative height of a protrusion h/D=(25-87.5)·10^-3, the relative axial pitch p/D=0.16-12.73. It is revealed that the hydraulic resistance of tubes with helical finning increases by a factor of 1.1 to 11.7 and the augmentation of the Nusselt number varies in the range 1.05-3.35.

Results of experimental investigation of hydrodynamics and heat transfer in turbulent boundary layer before and after a rectangular rib with sharp corners and a rectangular rib with round top corners are presented. The rib is placed on the flat plate and heated by the law of q_w=const. Experimental studies were conducted using hot-wire anemometry system by Dantec Dynamics and obtained are new experimental data on the mean and fluctuating characteristics in turbulent boundary layer in flow over ribs – in the laminar sublayer and transition region. A faster growth of the coefficient heat transfer is observed from the distribution features of drag and heat transfer coefficients..

The technical progress in information and communication sphere leads to a sharp increase in the use of radio electronic devices. Functioning of radio electronics is accompanied by release of thermal energy, which must be diverted from the heat-stressed element. Moreover, using of electronics at negative temperatures, on the contrary, requires supply of a certain amount of heat to start the system. There arises the task of creating a system that allows both to supply and to divert the necessary amount of thermal energy.

The development of complex thermostabilization systems for radio electronic equipment is due to increasing the efficiency of each of its elements separately. For more efficient operation of a heat exchanger, which directly affects the temperature of the heat-stressed element, it is necessary to calculate the mode characteristics and to take into account the effect of its design parameters. The results of optimizing the microchannel heat exchanger are presented in the article. The target optimization functions are the mass, pressure drop and temperature. The parameters of optimization are the layout of porous fins, their geometric dimensions and coolant flow. For the given conditions, the optimum variant of porous microchannel heat exchanger is selected.

The serpentine-like one and half-pass cooling channel systems are primarily used in blades fabricated by the lost-wax casting process. The heat transfer turbulators like cross-sectional or angled ribs used in channels of the midchord region failed to eliminate the temperature irregularity from the suction and pressure sides, which is reaching 200°C for a first stage blade of the high-pressure turbine for an aircraft engine. This paper presents the results of a numerical and experimental test of an advanced heat transfer augmentation system in radial channels developed for alignment of the temperature field from the suction and pressure sides. A numerical simulation of three-dimensional coolant flow for a wide range of Reynolds numbers was carried out using ANSYS CFX software. Effect of geometrical parameters on the heat removal asymmetry was determined. The test results of a blade with the proposed intensification system conducted in a liquid-metal thermostat confirmed the accuracy of calculations. Based on the experimental data, the dependencies for calculation of heat transfer coefficients to the cooling air in the blade studied were obtained.

We have carried out Investigation into aerodynamic and convective heat transfer of the annular channel. Inner or outer surface of annular channel has shape of blunt-nosed cone tapering to outlet end. Truncated cone connects to a cyclone swirling flow generator. Asymmetric and unsteady flow from the swirling generator in the shape of periodic process gives rise to the formation of secondary flows of the type Taylor-Görtler vortices. These vortices occupy the whole space of the annular channel, with the axes, which coincide with the motion direction of the major stream. Contraction of cross-sectional area of channel (in both cases 52%) causes a marked increase in total velocity of flow, primarily due to its axial component and promotes a more intensive vortex generation. Vortex structures have a significant influence on both average heat transfer and surface distribution. At cross-sections of the annular channel we observe similarity of curves describing distribution of total velocity about wall and heat flux density on the surface. The coordinates of maximum and minimum values of velocity and heat flux coincide. At the average cross-section channel of maximum value of heat transfer is greater than minimum of about by a factor of 2.7 times for outer heat transfer surface and about by a factor of 1.7 times for inner heat transfer surface. Taper channel has a much higher influence on heat transfer of the inner surface than the outer surface and manifests itself at lower values of dimensionless axial coordinate. For the investigated taper cone geometry of the annular channel the heat transfer coefficient of inner surface increases at the outlet section and exceeds value in comparison with straight-line section by 91 ... 98%. Heat transfer of the outer cylinder in the same section increases only by 5 ... 11%. The increase in average heat transfer over the surfaces is 36% and 4% respectively.

While formulating a mathematical model of the flow and interaction between oxygen-methane fuel combustion products with tangentially swirled ballast water injected in the end of the combustion chamber in CAE product Fluent, which integrated into the ANSYS Workbench platform, the problem of structural-parametric synthesis is solved for structure optimization of the model. Equations are selected from the catalogue of Fluent physical models. Also optimization helps to find "regime" model parameters that determine the specific implementation of the model inside the synthesized structure. As a result, such solutions which were developed during creation of a numerical algorithm, as the choice of a turbulence model and the state equation, the methods for determining the thermodynamic thermophysical characteristics of combustion products, the choice of the radiation model, the choice of the resistance law for drops, the choice of the expression which allows to evaluate swirling flows lateral force, determination of the turbulent dispersion strength, choice of the mass exchange law, etc. Fields of temperature, pressure, velocity and volume fraction of phases were obtained at different ballast water mass flows. Dependence of wall temperature from mass flow of ballast water is constructed, that allows us to compare results of the experiment and mathematical modeling.

The results of film cooling numerical simulation over a flat plate with coolant supply through a single span-wise array of inclined (α = 30°) holes arranged inside cylindrical, triangular, and hemispherical dimples are represented in the paper. Such configurations are of a great practical interest for application in advanced blade cooling systems of high-performance gas turbines. The schemes with coolant supply into triangular and hemispherical dimples were first proposed and patented by the IET of the NAS of Ukraine. For numerical simulation the ANSYS CFX 14 commercial code was used. Numerical simulation were carried out in a wide range of the blowing ratio parameter varied from 0.5 to 2.0. For low blowing ratio parameter (m = 0.5) the laterally averaged film cooling efficiency is actually the same for all investigated schemes over the main film cooling area. In this area, the most simple in terms of the film cooling production technology configuration can be used. At the medium and high blowing ratios (m = 1.0 or higher) all investigated film cooling schemes allow to increase the laterally averaged film cooling efficiency in comparison with the traditional cooling scheme with single row of incline holes. In this case the configuration with coolant supply into triangular dimples of the «crater» type demonstrates the best film cooling efficiency due to significant reduction in the intensity and scale of the "kidney" vortex beyond configuration, as well as due to decrease in the coolant blowing non-uniformity factor.

The conditions for the realization of energy-saving heat exchange enhancement are experimentally determined, in which the increase in heat transfer in the investigated surface ducts is equal to the growth of aerodynamic losses. A method for determining the geometric and regime parameters of surface ducts, which determine the energy-saving regimes of heat exchange enhancement, is implemented. Energy-saving enhancement of heat transfer in the interrupted ducts and channels with ridges and valleys allows, respectively, to 2.78 and 1.40 times to reduce the heat exchange surface and the mass of the heat exchanger with the previous energy costs. The results of the research make it possible to eliminate the intuitive choice of the shape and parameters of the ducts of the heat exchanger surfaces and to ensure their operation in energy-saving regimes.

One of the efficient ways to disrupt and redevelop the boundary layer for the purpose of heat transfer enhancement is application of discrete roughness elements in the form of spanwise ribs. To further improve the efficiency of this method, the flow can be exposed to some additional forcing. Forced pulsations of flow are considered to be a promising technique. The paper studies the combined effect of discrete roughness elements and forced pulsations of flow on heat transfer. Turbulent pulsating flow in the entrance region of the channel with discrete roughness elements has been considered. The Reynolds number based on the channel hydraulic diameter was Re_D = 18200, relative rib height e/h = 0.117, rib pitch p/e = 10. Strouhal number, Sr, and relative amplitude of forced velocity pulsations, β, varied in the following ranges: Sr = 0.04 ... 0.6; β = 0.15 ... 0.8. The Strouhal number was based on the bulk velocity and the rib height. Smoke visualization of flow downstream of the third rib in the channel has revealed the effects introduced by forced periodic pulsations to mass transfer behavior. The obtained flow behavior allowed qualitative and quantitative classification of the flow pattern.

One of the famous ways to improve efficiency of a heat exchanger is associated with the topography of the surfaces being in contact with coolants. So, use of hemispherical dimples leads to progressive growth of the relative heat transfer coefficient compared to increase of the relative resistance coefficient. Usually a plate having the spherical dimple intensifiers for heat transfer is considered as a flat one with embedded cavities. However, such a plate can be also considered as the plate with inbuilt fins which are formed by dimples in the form of ball segments. Given that for the flow of fluid (gas) from left to right, the minimum local heat transfer enhancement occurs in the first (left) half of the dimples, and the maximum falls on the edge of the second (right) half, we obtained an analytical solution describing the temperature distribution along the height of the fin. In the solution we used the Harper-Brown approach. Presented are the results of the calculation of the efficiency of the surface on the parameters of the considered fin and on a known value of the average heat transfer coefficient corresponding to the stage of the fluid flow steady state.

The results of an experimental investigation on the effect of large-scale vortex structures on the heat transfer and drag coefficients on smooth wall are presented. Cylinder of diameter Ø=8 mm was installed in a channel of height H=30 mm. The models were installed at distance of 40 mm from cylinder. The gap Y₀ between the wall and the edge of the cylinder varied from 1 to 21 mm. The value of the averaged relative drag coefficient c_x/c_x0 as well as the relative heat transfer coefficient St/St₀ were determined behind the cylinder at different flow velocity and position of cylinder in the channel. The maximum value of c_x/c_x0=1.48-2.04 (depending on the Reynolds number Re_x) is obtained for the case of Y₀=11 mm. At Y₀=21 mm the shear stress on the wall decreases to c_x/c_x0=0.00-0.17. At Y₀=1-2 mm, negative values of the c_x/c_x0 are observed. The minimum value c_x/c_x0=-1.01–-0.71 corresponds to smallest gap Y₀=1 mm. The local value St/St₀ for Y₀=1-2 mm has maximum at distance of 80 mm from cylinder's axis. With further increase in Y₀ to 9 mm, the value of St/St₀ decreases along the plate. At Y₀=11 mm local maximum is observed at distance of 90 mm from cylinder's axis. At Y₀=21 mm, the values of St/St₀=1. The local values of St/St₀ varied in range St/St₀=1.0 2.5.

The paper presents results of the investigation of the thermal resistance in soil thermal stabilizers in the permafrost region. The schemes of the composite and single thermostabilizers, the dependences of the evaporator temperature of the heat stabilizer are presented. The thermal resistance is presented depending on the refrigerating capacity for Freon R22 and water.

When evaluating the effectiveness of the heat exchange surfaces in the main considered characteristics such as heat flow (Q, Watt), the power required for pumps (N, Watt), and surface area of heat transfer (F, m²). The most correct comparison provides a comparison "ceteris paribus". Carried out performance comparison "ceteris paribus" in-line and staggered configurations of bundles with a circular pipes can serve as a basis for the development of physical models of flow and heat transfer in tube bundles with tubes of other geometric shapes, considering intertubular stream with attached eddies. The effect of longitudinal and transverse steps of the pipes on the energy efficiency of different configurations would take into account by mean of physical relations between the structure of shell side flow with attached eddies and intensity of transfer processes of heat and momentum. With the aim of energy-efficient placement of tubes, such an approach opens up great opportunities for the synthesis of a plurality of tubular heat exchange surfaces, in particular, the layout of the twisted and in-line-diffuser type with a drop-shaped pipes.

The paper describes and considers the possibility of using the method of cooling by a gas-water spray of a working area heated by a beam of charged particles. The design of a gas-water spray generator and an experimental installation for visualizing the process of outflow of the working environment from it has been developed, the necessary components of the system have been prepared, and an experimental setup has been installed. The cooling of the surface is carried out by evaporation of the impalpable drops of water from spray flow. Photographs of coolant outflow from the gas-water spray generator were obtained. The experiments revealed that the dispersion of liquid drops in the spray flow increases with air pressure rise, with a constant water consumption. It was concluded from the experiments carried out that the optimum dispersity of drops is achieved at air pressure (2÷3)·105 Pa and water flow (50÷100) g/s.

The effectiveness of the heat exchange intensifier "rib-twisted wire" is considered in this paper. The main goal was to study the influence of the wire coiling step t on heat transfer and hydraulic resistance for different values $\dot{H}$ of the dimensionless height of the edge $\dot{H}$, as well as some results on heat exchange during bubbly boiling in an annular channel.

Given:

• a brief description and an image of the heat exchange intensifier "rib-twisted wire";

• generalized results of studies of heat exchange and hydraulic resistance in the annular channel in the single-phase convection with different geometric characteristics of the intensifier;

• empirical correlations of the generalized experimental results that allow to calculate the coefficient of hydraulic resistance and heat transfer in the range of regime parameters in the single-phase convection that is being studied.

• some results of experiments in bubbly boiling regimes and near-critical thermal loads.

The results of experimental research of gas dynamics and heat transfer in the exhaust process in piston internal combustion engines are presented. Studies were conducted on full-scale models of piston engine in the conditions of unsteady gas-dynamic (pulsating flows). Dependences of the instantaneous flow speed and the local heat transfer coefficient from the crankshaft rotation angle in the exhaust pipe are presented in the article. Also, the flow characteristics of the exhaust gases through the exhaust systems of various configurations are analyzed. It is shown that installation of the ejector in the exhaust system lead to a stabilization of the flow and allows to improve cleaning of the cylinder from exhaust gases and to optimize the thermal state of the exhaust pipes. Experimental studies were complemented by numerical simulation of the working process of the DM-21 diesel engine (production of "Ural diesel-motor plant"). The object of modeling was the eight-cylinder diesel with turbocharger. The simulation was performed taking into account the processes nonstationarity in the intake and exhaust pipes for the various configurations of exhaust systems (with and without ejector). Numerical simulation of the working process of diesel was performed in ACTUS software (ABB Turbo Systems). The simulation results confirmed the stabilization of the flow due to the use of the ejection effect in the exhaust system of a diesel engine. The use of ejection in the exhaust system of the DM-21 diesel leads to improvement of cleaning cylinders up to 10 %, reduces the specific fuel consumption on average by 1 %.

Results of experimental and analytical studies of the plant main element – plant turbomachine (turbo-expander) operating on organic Rankine cycle were obtained for facilities of the heat supply systems of small-scale power generation. At simultaneous mathematical modeling and experimental studies it was found that the best working medium to be used in the turbomachines of these plants is Freon R245fa which has the most suitable calorimetric properties to be used in the cycle. The mathematical model of gas flow in the turbomachine was developed. The main engineering dependencies to calculate the optimal design parameters of the turbomachine were obtained. The engineering problems of providing the minimum axial size of the turbomachine impeller were solved and the main design elements were unified.

The growing aspiration to energy saving and efficiency of energy leads to necessity to build tight enough buildings. As a result of this the quantity of infiltration air appears insufficient for realization of necessary air exchange in. One of decisions of the given problem is development and application for ventilation of premises of the decentralized forced-air and exhaust systems (DFAES) with recuperative or regenerative heat-exchangers. For an estimation of efficiency of DFAES following basic parameters have been certain: factor of energy saving; factor of efficiency of energy; factor of a heat transfer; factor of an effective utilization of a surface of heat exchange. Were estimated temperature of forced air; actual speed of an air jet on an entrance in a served zone; actual noise level; the charge of external air. Tests of DFAES were spent in natural conditions at which DFAES influenced all set of factors both an external climate, and an internal microclimate of a premise, and also the arrangement on a wind side or behind wind side of a building, influence of surrounding building, fluctuation of temperature of external air is considered. Proceeding from results and the analysis of the lead researches recommendations have been developed for development and manufacture of new sample of DFAES.

The paper explores challenges of power supply for remote users through the case of the Northern Sea Route (NSR) supportive infrastructure development and specially nature protected areas (NPA) of the Russian Arctic. The study is based on a comprehensive analysis of relevant data of the state of renewable energy in the Russian Arctic. The paper gives policy recommendations on how to extend the use of renewable energy power plants in the region, optimize their input and increase cost-effectiveness and safety.

Analysis of existing designs of boilers with low power consumption showed that the low efficiency of the latter is due to the fact that they work in most cases when the heating period in the power range is significantly less than the nominal power. At the same time, condensing boilers do not work in the most optimal mode (in condensing mode) in the central part of Russia, a significant part of their total operating time during the heating season. This is due to existing methods of equipment selection and joint operation with heating systems with quantitative control of the coolant. It was also revealed that for the efficient operation of the heating system, it is necessary to reduce the inertia of the heat generating equipment. Theoretical patterns of thermal processes in the furnace during combustion gas at different radiating surfaces location schemes considering the influence of the very furnace configuration, characterized in that to reduce the work condensing boiler in conventional gas boiler operation is necessary to maintain a higher temperature in the furnace (in the part where spiral heat exchangers are disposed), which is possible when redistributing heat flow - increase the proportion of radiant heat from the secondary burner emitter allow Perey For the operation of the condensing boiler in the design (condensation) mode practically the entire heating period.

The article discusses the main thermal processes in the automated control systems for heat consumption (ACSHC) of buildings, schematic diagrams of these systems, mathematical models used for description of thermal processes in ACSHC. Conducted verification represented by mathematical models. It was found that the efficiency of the operation of ACSHC depend from the external and internal factors. Numerical study of dynamic modes of operation of ACSHC.

The assessment of the power efficiency realized in the current of heat supply system of technology of regulation of loading of the hot water supply system, considering unevenness consumption of hot water is executed. For the purpose of definition the applicability boundary of realized technology comparative analysis of indicators of the effectiveness of its work within the possible range of the parameters of regulations. Developed a software application "The calculation of the total economy of fuel and energy resources in the hot water supply system when you change of the parameters of regulations", which allows on the basis of multivariate calculations analyses of their results, to choose the optimum mode of operation heat supply system and to assess the effectiveness of load regulation in the hot water supply system.

The report describes issues in connection with improving urban district heating systems from combined heat power plants (CHPs), to propose the ways for improving the reliability and the efficiency of the energy usage (often referred to as "energy efficiency") in such systems. The main direction of such urban district heating systems improvement suggests transition to combined heating systems that include structural elements of both centralized and decentralized systems. Such systems provide the basic part of thermal power via highly efficient methods for extracting thermal power plants turbines steam, while peak loads are covered by decentralized peak thermal power sources to be mounted at consumers' locations, with the peak sources being also reserve thermal power sources. The methodology was developed for assessing energy efficiency of the combined district heating systems, implemented as a computer software product capable of comparatively calculating saving on reference fuel for the system.

The relevance of the topic due to the decision of problems of the economy of resources in heating systems of buildings. To solve this problem we have developed an integrated method of research which allows solving tasks on optimization of parameters of heat exchangers. This method decides multicriteria optimization problem with the program nonlinear optimization on the basis of software with the introduction of an array of temperatures obtained using thermography. The author have developed a mathematical model of process of heat exchange in heat exchange surfaces of apparatuses with the solution of multicriteria optimization problem and check its adequacy to the experimental stand in the visualization of thermal fields, an optimal range of managed parameters influencing the process of heat exchange with minimal metal consumption and the maximum heat output fin heat exchanger, the regularities of heat exchange process with getting generalizing dependencies distribution of temperature on the heat-release surface of the heat exchanger vehicles, defined convergence of the results of research in the calculation on the basis of theoretical dependencies and solving mathematical model.

Currently, major part of climatic system, are stationary in projected mode only. At the same time, many modern industrial sites, require constant or periodical changes in technological process. That is 80% of the time, the industrial site is not require ventilation system in projected mode and high precision of climatic parameters must maintain. While that not constantly is in use for climatic systems, which use in parallel for different rooms, we will be have a problem for balance of duct system. For this problem, was created the algorithm for quantity regulation, with minimal changes. Dynamic duct system: Developed of parallel control system of air balance, with high precision of climatic parameters. The Algorithm provide a permanent pressure in main duct, in different a flow of air. Therefore, the ending devises air flow have only one parameter for regulation – flaps open area. Precision of regulation increase and the climatic system provide high precision for temperature and humidity (0,5C for temperature, 5% for relative humidity). Result: The research has been made in CFD-system – PHOENICS. Results for velocity of air in duct, for pressure of air in duct for different operation mode, has been obtained. Equation for air valves positions, with different parameters for climate in room's, has been obtained. Energy saving potential for dynamic duct system, for different types of a rooms, has been calculated.

The generalized mathematical model of decision-making in the problem of planning and mode selection providing required heat loads in a large heat supply system is considered. The system is multilevel, decomposed into levels of main and distribution heating networks with intermediate control stages. Evaluation of the effectiveness, reliability and safety of such a complex system is carried out immediately according to several indicators, in particular pressure, flow, temperature. This global multicriteria optimization problem with constraints is decomposed into a number of local optimization problems and the coordination problem. An agreed solution of local problems provides a solution to the global multicriterion problem of decision making in a complex system. The choice of the optimum operational mode of operation of a complex heat supply system is made on the basis of the iterative coordination process, which converges to the coordinated solution of local optimization tasks. The interactive principle of multicriteria task decision-making includes, in particular, periodic adjustment adjustments, if necessary, guaranteeing optimal safety, reliability and efficiency of the system as a whole in the process of operation. The degree of accuracy of the solution, for example, the degree of deviation of the internal air temperature from the required value, can also be changed interactively. This allows to carry out adjustment activities in the best way and to improve the quality of heat supply to consumers. At the same time, an energy-saving task is being solved to determine the minimum required values of heads at sources and pumping stations.

The paper is devoted to the analysis of fuel economy efficiency increase possibility at thermal power plants (TPP) due to the transition from the use of black oil as a reserve fuel to liquefied natural gas (LNG) produced at the very station. The work represents the technical solution that allows to generate, to store and to use LNG as the reserve fuel TPP. The annual amounts of black oil and natural gas that are needed to ensure the reliable operation of several power plants in Russia were assessed. Some original schemes of the liquefied natural gas production and storing as alternative reserve fuel generated by means of application of expansion turbines are proposed. The simulation results of the expansion process for two compositions of natural gas with different contents of high-boiling fractions are presented. The dependences of the condensation outlet and power generation from the flow initial parameters and from the natural gas composition are obtained and analysed. It was shown that the choice of a particular circuit design depends primarily on the specific natural gas composition. The calculations have proved the effectiveness and the technical ability to use liquefied natural gas as a backup fuel at reconstructed and newly designed gas power station.

This paper deals with the variant of modernization of the heat point within urban heat supply network in order to create the system of heat and cold supply on its basis, providing the suppliers with heat in cold months and with heat and cold in warm months. However, in cold months in the course of heating system operation, the reverse delivery water temperature is maintained below 40 °C. The analysis of heat and power indicators of the heat and cold supply system under different operating conditions throughout the year was conducted. The possibility to use the existing heat networks for the cold supply needs was estimated. The advantages of the system over the traditional heat supply systems that use Combined Heat and Power (CHP) plant as a heat source as exemplified by heat supply system from CHP with ST-80 turbine were demonstrated.

Low pressure district heating systems have low breakdown rate and allow decreasing heat carrier transportation energy cost by means of avoiding throttling of available water head. One of the basic elements of such systems is thermohydraulic dispatcher (THD) which separates primary circuit and secondary circuit (or circuits) that allows avoiding mutual hydraulic influence of circuits on each other and reducing water heads of network pumps. Analysis of perspective ways of using thermohydraulic dispatcher (THD) in low temperature district heating systems is made in this paper. Principal scheme and mathematical model of low pressure and temperature district heating system based on CHP generation with THD are considered. The main advantages of such systems are pointed out.

Currently the actual problem is a precise definition of the normative and actual heat loss. Existing methods - experimental, on metering devices, on the basis of mathematical modeling methods are not without drawbacks. Heat losses establishing during the heat carrier transport has an impact on the tariff structure of heat supply organizations. This quantity determination also promotes proper choice of main and auxiliary equipment power, temperature chart of heat supply networks, as well as the heating system structure choice with the decentralization. Calculation of actual heat loss and their comparison with standard values justifies the performance of works on improvement of the heat networks with the replacement of piping or its insulation. To determine the cause of discrepancies between normative and actual heat losses thermal tests on the magnitude of the actual heat losses in the 124 sections of heat networks in Kazan. As were carried out the result mathematical model of the regulatory definition of heat losses is developed and tested. This model differ from differs the existing according the piping insulation type. The application of this factor will bring the value of calculative normative losses heat energy to their actual value. It is of great importance for enterprises operating distribution networks and because of the conditions of their configuration and extensions do not have the technical ability to produce thermal testing.

When conducting an energy survey of heat supply enterprise operating several boilers located not far from each other, it is advisable to assess the degree of heat supply efficiency from individual boiler, the possibility of energy consumption reducing in the whole enterprise by switching consumers to a more efficient source, to close in effective boilers. It is necessary to consider the temporal dynamics of perspective load connection, conditions in the market changes. To solve this problem the radius calculation of the effective heat supply from the thermal energy source can be used. The disadvantage of existing methods is the high complexity, the need to collect large amounts of source data and conduct a significant amount of computational efforts. When conducting an energy survey of heat supply enterprise operating a large number of thermal energy sources, rapid assessment of the magnitude of the effective heating radius requires. Taking into account the specifics of conduct and objectives of the energy survey method of calculation of effective heating systems radius, to use while conducting the energy audit should be based on data available heat supply organization in open access, minimize efforts, but the result should be to match the results obtained by other methods. To determine the efficiency radius of Kazan heat supply system were determined share of cost for generation and transmission of thermal energy, capital investment to connect new consumers. The result were compared with the values obtained with the previously known methods. The suggested Express-method allows to determine the effective radius of the centralized heat supply from heat sources, in conducting energy audits with the effort minimum and the required accuracy.

Analysis of existing designs of boilers with low power consumption showed that the low efficiency of the latter is due to the fact that they work in most cases when the heating period in the power range is significantly less than the nominal power. At the same time, condensing boilers do not work in the most optimal mode (in condensing mode) in the central part of Russia, a significant part of their total operating time during the heating season. This is due to existing methods of equipment selection and joint operation with heating systems with quantitative control of the coolant. It was also revealed that for the efficient operation of the heating system, it is necessary to reduce the inertia of the heat generating equipment. Theoretical patterns of thermal processes in the furnace during combustion gas at different radiating surfaces location schemes considering the influence of the very furnace configuration, characterized in that to reduce the work condensing boiler in conventional gas boiler operation is necessary to maintain a higher temperature in the furnace (in the part where spiral heat exchangers are disposed), which is possible when redistributing heat flow - increase the proportion of radiant heat from the secondary burner emitter allow Perey For the operation of the condensing boiler in the design (condensation) mode practically the entire heating period.

In this paper the description of the basic equations which can be used for calculation of melting of fuel and cladding of the fast reactor, moving of the melt on a fuel pin surface and its solidification is presented. The special attention is given speed of calculation algorithms and fidelity of the phenomena which are observed at a stage of severe accidents in fast reactors.

For check of working capacity of initial models, numerical calculations of Stefan-type problems on front movement of melting/solidification in cylindrical geometry are presented. Comparison with the solutions received by known analytical methods is executed. For validation of the numerical realization of calculation algorithms the analysis is carried out and experiments in which melting of the model fuel pins of fast reactors was studied are chosen. On the basis of the chosen experiments calculation schemes taking into account initial and boundary conditions are prepared and modeling is performed. Modeling results are shown in the present paper. Estimation of calculation error of the basic physical parameters is done by results of the modeling and conclusions are drawn on a correctness of algorithms operation.

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.

The results of studies are aimed at developing theoretical foundations and instrumentation system to ensure a technology of vortex diagnostics of the state of flows of fluids for nuclear power installations with power water reactors and fast neutrons reactors with liquid-metal coolants. The technology of vortex diagnostics is based on the study of acoustic, magneto-hydrodynamic and resonant effects related to the formation of stable vortex structures. For creation a system of monitoring and diagnostics of the crisis phenomena due to hydrodynamics of the flow, it is proposed to use acoustic method to record the radiation of elastic waves in the fluids caused by the dynamic local rearrangement of its structure.

The verification of the FENIA finite element code on some problems and an example of its application are presented in the paper. The code is being developing for 3D modelling of thermal, mechanical and hydrodynamical (THM) problems related to the functioning of deep geological repositories. Verification of the code for two analytical problems has been performed. The first one is point heat source with exponential heat decrease, the second one - linear heat source with similar behavior. Analytical solutions have been obtained by the authors. The problems have been chosen because they reflect the processes influencing the thermal state of deep geological repository of radioactive waste. Verification was performed for several meshes with different resolution. Good convergence between analytical and numerical solutions was achieved. The application of the FENIA code is illustrated by 3D modelling of thermal state of a prototypic deep geological repository of radioactive waste. The repository is designed for disposal of radioactive waste in a rock at depth of several hundred meters with no intention of later retrieval. Vitrified radioactive waste is placed in the containers, which are placed in vertical boreholes. The residual decay heat of radioactive waste leads to containers, engineered safety barriers and host rock heating. Maximum temperatures and corresponding times of their establishment have been determined.

The largest contribution to the probable frequency of core damage is blackout events. The main component of the heat capacity at each reactor within a few minutes following a blackout is the heat resulting from the braking of beta-particles and the transfer of gamma-ray energy by the fission fragments and their decay products, which is known as the residual heat. The power of the residual heat changes gradually over a long period of time and for a VVER-1000 reactor is about 15–20 MW of thermal power over 72 hours. Current cooldown systems increase the cost of the basic nuclear power plants (NPP) funds without changing the amount of electricity generated. Such systems remain on standby, accelerating the aging of the equipment and accordingly reducing its reliability. The probability of system failure increases with the duration of idle time. Furthermore, the reactor residual heat energy is not used. A proposed system for cooling nuclear power plants involves the use of residual thermal power to supply the station's own needs in emergency situations accompanied by a complete blackout. The thermal power of residual heat can be converted to electrical energy through an additional low power steam turbine. In normal mode, the additional steam turbine generates electricity, which makes it possible to ensure spare NPP and a return on the investment in the reservation system. In this work, experimental data obtained from a Balakovo NPP was analyzed to determine the admissibility of cooldown of the reactors through the 2nd circuit over a long time period, while maintaining high-level parameters for the steam generated by the steam generators.

The report addresses the issue of the optimal water level in the horizontal steam generators of NPP with WWER. On the one hand, the level needs to be kept at the lower limit of the allowable range, as gravity separation, steam will have the least humidity and the turbine will operate with higher efficiency. On the other hand, the higher the level, the greater the supply of water in the steam generator, and therefore the higher the security level of the unit, because when accidents involving loss of cooling of the reactor core, the water in the steam generators, can be used for cooling. To quantitatively compare the damage from higher level to the benefit of improving the safety was assessed of the cost of one cubic meter of water in the steam generators, the formulated objective function of optimal levels control. This was used two-dimensional separation characteristics of steam generators. It is demonstrated that the security significantly shifts the optimal values of the levels toward the higher values, and this bias is greater the lower the load unit.

The paper describes the calculation procedure of heating element thermal state based on the experimental study of heating element thermal processes under impulse heating in a subcooled pool. This procedure can be used to analyze the thermal state of the reactor fuel element in case of accidents with unauthorized introduction of excessive reactivity in process of core loading and accidents in pool-type reactors.

The article discusses the combining nuclear power plants (NPP) with pressurized water reactors and distillation-desalination plants (DDP), their joint mode of operation during periods of coating failures of the electric power load graphs and thermo-economical efficiency. Along with the release of heat and generation of electric energy a desalination complex with the nuclear power plant produces distillate. Part of the selected steam "irretrievably lost" with a mix of condensation of this vapor in a desalination machine with a flow of water for distillation. It means that this steam transforms into condition of acquired product - distillate. The article presents technical solutions for the return of the working fluid for turbine К-1000-60/1500-2 и К-1200-6,8/50, as well as permissible part of low pressure regime according to the number of desalination units for each turbine. Patent for the proposed two-product energy complex, obtained by Gagarin State Technical University is analyzed. The energy complex has such system advantages as increasing the capacity factor of a nuclear reactor and also allows to solve the problem of shortage of fresh water. Thermo-economics effectiveness of this complex is determined by introducing a factor-"thermo-economic index". During analyzing of the results of the calculations of a thermo-economic index we can see a strong influence of the cost factor of the distillate on the market. Then higher participation of the desalination plant in coverage of the failures of the graphs of the electric loading then smaller the payback period of the NPP. It is manifested more clearly, as it's shown in the article, when pricing options depend on time of day and the configuration of the daily electric load diagram. In the geographical locations of the NPPs with PWR the Russian performance in a number of regions with low freshwater resources and weak internal electrical connections combined with DDP might be one of the ways to improve the competitiveness of NPPs, especially for foreign coastal areas.

There was carried out an analysis of technical characteristics of boiler houses in a number of Russian NPPs. We justified the possibility of their usage for autonomous generation of electrical energy and improvement of maneuvering properties of power complexes as a single object of regulation, as well as the possibility of increasing the total generation capacity of NPP power units during peak hours. Then the selection of the main equipment of house boiler for its autonomous work was done. There were composed basic thermal diagrams of the power complex on the basis of NPP start-up boiler (SUB) and the satellite turbine. The article also considers some options of reconstruction of SUB into the heat-recovery boiler. The developed power complexes are designed to be used on the basis of the two-loop NPP with pressurized power reactors (PWR). They can be applied with serial and projected domestic NPP units with the aim of getting more power, improving the plant capacity factor (PCF), as well as with the aim of NPP participation in the regulation of the load curve above the nominal value with partial replacement of new construction. The power complexes can be a relevant solution in the light of the energy strategy of the Russian Federation, which is aimed at, firstly, further improvement of efficiency and safety at the NPP, and, secondly, solving the problem of adequate maneuverability and ensuring the adjustment range limits in power systems with high share of nuclear power plants. Implementation of new hybrid thermal diagrams allows simultaneous increase in the safety of NPP, and usage of nuclear power plants emergency frequency control in power systems by fast load drop and rise by -4÷+2 % of the nominal value. Due to the usage of different fuels in power complexes, uranium loading in the core of reactor facilities and gas in SUB, there was proposed and formalized the criterion of "thermoeconomic index". This criterion represents the ratio of the gross receipt from the sale of electricity to the total cost of fuel of all kinds, spent on ensuring power efficiency.

The high-temperature oxidation tests were carried out for the regular fuel rod claddings specimens made of sponge-based zirconium alloy (E110G) and for the accident tolerant fuel (ATF) ones – pure vacuum melted molybdenum (VCPM) and niobium alloy (Nb-1%Zr). The tests were carried out under the ambient pressure p ∼ 0.1 MPa in pure water steam. The experimental data on the oxidation characteristics were obtained for E110G specimens in the temperature range T = 1100 − 1500 °C, that for VCPM and Nb-1%Zr are investigated under extended temperature-duration range (more than 1 hour). The thermal effects of molybdenum (Q_SMR) and niobium (Q_SNR) interactions with steam were defined and the derived oxidation rate constants for refractory metals were compared with the known ones. Based on the computations performed with PARAM-TG code the high-temperature oxidation characteristics of model fuel assemblies of large-scale facilities under LOCA conditions with regular and ATF claddings were compared. It was shown that Zr-steam interaction of fuel rod cladding (Q_SZR) is more intensive compared with VCPM and Nb-1%Zr ones under investigated conditions.

This paper provides the description of temperature cycle testing of U-Zr heterogeneous fuel composition. The composition is essentially a niobium-doped zirconium matrix with metallic uranium filaments evenly distributed over the cross section. The test samples 150 mm long had been fabricated using a fiber-filament technology. The samples were essentially two-bladed spiral mandrel fuel elements parts. In the course of experiments the following temperatures were applied: 350, 675, 780 and 1140 °C with total exposure periods equal to 200, 30, 30 and 6 hours respectively. The fuel element samples underwent post-exposure material science examination including: geometry measurements, metallographic analysis, X-ray phase analysis and electron-microscopic analysis as well as micro-hardness measurement. It has been found that no significant thermal swelling of the samples occurs throughout the whole temperature range from 350 °C up to 1140 °C. The paper presents the structural changes and redistribution of the fuel component over the fuel element cross section with rising temperature.

Created new scientific direction: "Diagnosis, prognosis and prevention of vibration - acoustic resonances in the nuclear power plant (NPP) equipment. The possibility of using methods for calculating and analyzing electric oscillation systems in the study of the properties of acoustic systems with a two-phase medium is proved, based on the similarity of the differential equations describing the state of these systems. Is shown that the developed methods can be used to predict and prevent the occurrence of vibration - acoustic resonances in the NPP equipment. Is shown that the volume of pressurizer at NPPs with VVER and PWR as well as boiling water reactor that exploded at Japan's NPP Fukushima Daiichi is a Helmholtz resonator, which contain water and steam volumes and able many times increases the impact on them of outside periodic oscillations. Paper presents most important results published long before the severe accidents at NPPs Three Mile Island (TMI), Chernobyl and Fukushima Daiichi that could be used for the prediction of a severe accident scenario, identification of measuring data and process control in order to minimize the damage. Worked out results also could be useful in another industrial technologies based on applications of single and two-phase flows.

Results of special measurements of coolant pressure oscillations in primary loops on unit No 3 of Novovoronezh NPP with VVER-440 are presented. Acoustical models and calculating algorithms for determinations of frequencies of acoustic standing waves (ASW) are designed. Models based on the Method of Electro-Acoustic Analogies gives a sensible interpretation of ASW sources. The calculated values of ASW frequencies for each acoustic element and for their compositions are presented. Identifying the sources of ASW in the first circuit held at all stages of the start-up power. Analysis of the results of comparison ASW rate with the measurement data of the main equipment vibration revealed a number of modes in which resonance of vibration with ASW occurs. Shown that developed approach can be used both in normal operation and in emergency modes for research and development of vibration - acoustic certification of reactor facilities; Improvements of process control and computer codes.

Nitride nuclear fuel is a perspective type of fuel for fast reactors. This type of fuel has a number of advantages, including high thermal conductivity, high density of uranium and low fission gas (FG) release together with moderate swelling. Modeling the change of fuel properties with burnup is of interest from the point of justifying the safe operation of fuel rods. Changes in the phase composition of the fuel during irradiation lead to a complex changes in its properties. This paper examine the thermal conductivity, diffusion coefficient of FG and solid-state swelling change in (U, Pu)N fuel with 20% plutonium content at various stoichiometry and oxygen and carbon impurities. The thermodynamic calculation of the phase composition was carried out with the help of the multi-purpose program complex ASTRA-4 in the burnup range 0-15% fima and temperature range 900-1800 K. The dependences of concentrations of phase inclusions from content of nitrogen and oxygen in the initial fuel are received. Their fraction can attain ∼ 50% by volume at significant burnups and deviations from the stoichiometric composition. It is shown, that the main phase inclusion is U₂N₃, the concentration of which increases with the burnup and stoichiometric coefficient growth of the initial fuel. The increase in stoichiometry leads to a significant decrease in thermal conductivity, an increase in the diffusion coefficient of FG in fuel, and with increasing burnup this effect is enhanced. The calculated solid-state swelling of the fuel is in range 0,25-0,5% per burnup %, which is in satisfactory agreement with the literature data.

The object of this study is a contact combined-cycle plant with the injection of dry saturated steam into a regenerative air heater and with water heating recovery boiler. Peculiarity of the scheme is that for cooling the turbine flow range and for injection, we used dry saturated steam and the mixing point is a regenerator. In order to reduce heat loss to the environment we additionally inserted water heating recovery boiler. The study was conducted using the software package "Computer analysis system for CCP and GTP combination". We introduced the results of the optional optimization parameters of working fluids, which were made according to the given scheme. Additional useful power increase of CCP occurs due to the use of steam cooling. Efficiency thus reaches 47.52% and the capacity of water heating recovery boiler reaches 2.1 MW. To verify the calculations, we used mathematical modeling method based on graph theory.

Noise is the most important factor of physical effects at normal operation thermal and nuclear power equipment. Increasing the safety of the power equipment of thermal power (TPS) and nuclear power stations (NPS) is important task. This task is also associated with a decreasing the noise from power equipment. The problem of noise reduction by thermal and nuclear power equipment in the surrounding areas is discussed. Here are the original theoretical developments of the education of the most intense noise sources. There is also given and original examples of devices to reduce noise from them: from steam emissions, draft machines, cooling towers, etc. Creating mathematical models of thermal or nuclear power plants allows us to consider the effect of the limiting factors in the development of the noise safety from TPP and NPS. Mathematical models allow us to study the effects of sound power sources and its amount, location of sources at the site, the mode of operation of the equipment, index of their direction, the orientation of the power equipment and other factors on the noise levels in the surrounding area. The results of the original tests various silencers and acoustic barriers are given. The importance of complex noise reduction on the totality of sources of noise to ensure noise sanitary standards in the surrounding area are shown.

The energy sector embraces solid oxide fuel cells (SOFC) since they are highly efficient and ecologically sound power generators. Yet, maintaining fuel cells sustainability in power units takes a lot of resources. Hence, we need to find the appropriate ways to increase the efficiency of the whole SOFC power system inclusive of its balance-of-plant equipment. This can facilitate our fuel and energy complex green transition through the SOFC technology introduction. As a matter of fact, anode gas recirculation is instrumental for boosting the SOFC power units efficiency. One of the challenges in developing the SOFC power unit with anode gas recirculation is to return the amount of anode gas appropriate for carbon deposition free reforming. The paper contains the anode gas recirculation ratio in the SOFC power units calculation method for various reforming temperatures. The safest operation modes of the SOFC power units with anode gas recirculation were determined. The 3 kW SOFC power unit with high temperature ejector and nickel-based catalyst for methane conversion was designed. For the given flow channel geometry, the high temperature ejector off-design performance was plotted. In addition, fields of temperature, pressure and velocities were plotted for the ejector design point using Ansys computational fluid dynamics software.

The condensing mode of operation steam boiler using as fuel blast furnace gas is analyzed. The heat transfer in the flue of the boiler is calculated, the maximum depth of the cooling of the flue gases is defined, the scheme of installation of the heat exchanger in the flue tract is developed. The optimal operating parameters of heat exchanger are defined.

An external wind has an adverse effect on the thermal efficiency of a cooling tower. At the top of the tower, the wind effect is manifested by the interaction of the incoming wind flow with the rising steam–air torch. Here a partial closing of the exit section of the cooling tower occurs, which reduces the free convective thrust and as a consequence reduces its cooling capacity. To reduce the adverse wind effect, a new aerodynamic method is developed for decreasing the negative wind impact on the thermal efficiency of the cooling tower through the use of its own kinetic energy. On the basis of the experimental studies on a laboratory model of the evaporative cooling tower, an optimal variant of a passive wind tip is created. Its optimal parameters under which the cooling capacity of the model with a wind load is maximum are determined.

It is shown that along with development of a heat and electrical energy on combined heat and power plants there is a possibility of implementation of the engineering procedures necessary in municipal economy, one of which is utilization of the snow and ice weight deleted during the winter period from city streets. New technologies for utilization of snow with use of low-potential sources of warmth at combined heat and power plant are offered. Scientific reasons are carried out them and comparative cost effectiveness analysis of developed technologies is made.

Methodology for thermodynamic analysis, fuel efficiency determination, and mathematical economic calculation model of comparative economic effectiveness of combined-cycle cogeneration plant (CCCP) are elaborated. CCCP with a single, dual and triple pressure heat-recovery steam generators (HRSG) are investigated with account for real-time use in Heating System. Employment of CCCP with a triple pressure HRSG ensure high value of system effectiveness. Modes of CCCP, conditional and functional scope of electricity and heat, and condition of construction investment financing of CCCP are main factors have an impact on effectiveness of different schemes of CCCP.

In this article we consider the questions connected with efficiency of equipment of gas transmission services of gas-compressor stations with the combined drive: with electrical one in addition to the existing gas turbine drive. In our research we consider geological and geographical regional features of the European part of Russia in coordination with an arrangement of large gas trunk pipelines, the existing boosting compressor stations (BCSs), the NPP, high-voltage transmission lines and saliferous basins suitable for creation of underground storage tanks for accumulation of stored air for needs of the gas turbine drive of gas transmission services. The following possible benefits of the schemes offered by authors are researched: the advantage of the additional charge of nuclear power plant units with increase in their capability utilization index during the off-peak periods account of transition to the electrical drive of superchargers; the advantage of use of stored air during the separate periods for partial unloading of the gas turbine drive; replacement of fuel gas as a valuable export resource; the advantage of improvements of the ecological indicators of already operating and expansions of layout opportunities of again constructing BCSs under the terms of acceptable concentration of emissions and to noise indicators. We provided the technique and results of calculation of technical-and-economic efficiency of re-equipment of BCSs under the offered scheme. In the offered method of application are considered: the mean effective performance factor of the NPP, the increase in the capability utilization index due to growth of gross generation and economy of nuclear fuel. We have considered questions of rationalization of configurations of residential settlements adjacent to BCSs under the terms of improvement of ecological indicators and to noise impact of BCSs by various number of working hours of the electrical drive in a year. The offered technique in combination with the specified starting base of data, which bases are provided in this article, will allow to perform the zoned optimization of a profile and the equipment of the compressor yard with BCSs taking into account already existing background and noise pollution Method for calculating the noise level from compressor stations.

It is shown that joint use of engineering infrastructure of centralized heat and water supply of consumers will be the cost-efficient decision for municipal services of the city. The new technology for regulated heating of drinking water in the condenser of steam turbines of combined heat and power plant is offered. Calculation of energy efficiency from application of new technology is executed.

Raising the efficiency and environmental friendliness of electric power generation from coal is the aim of numerous research groups today. The traditional approach based on the steam power cycle has reached its efficiency limit, prompted by materials development and maneuverability performance. The rival approach based on the combined cycle is also drawing nearer to its efficiency limit. However, there is a reserve for efficiency increase of the integrated gasification combined cycle, which has the energy efficiency at the level of modern steam-turbine power units. The limit of increase in efficiency is the efficiency of NGCC. One of the main problems of the IGCC is higher costs of receiving and preparing fuel gas for GTU. It would be reasonable to decrease the necessary amount of fuel gas in the power unit to minimize the costs. The effect can be reached by raising of the heat value of fuel gas, its heat content and the heat content of cycle air. On the example of the process flowsheet of the IGCC with a power of 500 MW, running on Kuznetsk bituminous coal, by means of software Thermoflex, the influence of the developed technical solutions on the efficiency of the power plant is considered. It is received that rise in steam-air blast temperature to 900°C leads to an increase in conversion efficiency up to 84.2%. An increase in temperature levels of fuel gas clean-up to 900°C leads to an increase in the IGCC efficiency gross/net by 3.42%. Cycle air heating reduces the need for fuel gas by 40% and raises the IGCC efficiency gross/net by 0.85-1.22%. The offered solutions for IGCC allow to exceed net efficiency of analogous plants by 1.8-2.3%.

The use of heat exchangers in which the working fluid before it enters the gas turbine is warmed up due to the combustion of fuel or other external energy source still is of interest due to the method advantages: the cleanliness of the working fluid; the ability of using cheap low-grade fuels, solar or nuclear energy; the possibility of usage of the closed gas turbine cycle with gases as a working medium, that having favorable thermodynamic properties in comparison with air (helium, CO₂, etc.). However, the desired gas turbine inlet temperature – up to 1,700°C currently not possible to provide even with the use of ceramic heat exchangers. Therefore, this technology is now being considered for solid-fuel micro gas turbines operating at temperatures 900-1100°C, or for reducing the need for fuel gas of integrated gasification combined cycle (IGCC) by the means of preheating of cyclic air as well as it is considered for solar gas turbines and gas turbines on the basis of high temperature gas cooled reactors. The authors have developed a metal recuperative air heater based on external combustion of coal for 500 MW IGCC power plant, the development of IGCC is determined by the Energy strategy of Russia for the period up to 2030. In the article the thermal characteristics of the heating of pressurized air, the possible options for the configuration of the heater, heat-resistant materials suitable for its production and the results of the feasibility calculations are considered. In conclusion the design that allows to significantly reduce the specific capital and operating costs for the heater compared to the classic one is proposed.

In this article there are given results of possible efficiency enhancement on thermal power plants with low-potential heat utilization. Intensive usage and restricted stocks of organic fuel creates demand of methods reducing its consumption. Thus, on thermal power plants one of important tasks is increasing of primary energy resources efficiency usage. In the research different thermal schemes based on thermal pumps, thermotransformers and installations using detander-generating aggregates were designed and thermal efficiency of these schemes was determined. Schemes calculation was executed using «Thermoflow» and «Gate Cycle» software products. It is shown, that implementation of various low-potential heat utilization technologies at thermal power plants leads to fuel economy. There are presented financial and economic performance indicators for the researched schemes.

The research results focused on improving the efficiency of gas-liquid cyclone separator with high operating pressure value of 2.5 MPa and a high flow density in the separation chamber are presented. With increasing of the gas dynamic pressure value increases the probability of entrainment processes and ascending film flow on the chamber walls which leads to a decrease of the separation efficiency. The gas-liquid separator construction provided the gas dynamic pressure reduce in the areas with high concentration of the liquid phase and excluded the separated liquid removal to the output collector is performed. This collector formed by conical confuser and round tube with external finning is located in the center of the separator's cylindrical chamber. A ribbed tubular flow conditioner is placed before collector's inlet face. The detailed structure of the flow in the separator by using a computational fluid dynamics based on RANS equations solving with the anisotropic RSM turbulence model is obtained. CFD simulation results are used to evaluate the main separator characteristics and the probability of entrainment processes and ascending film flow.

The paper gives an analysis of the current state and development trends of the energy sector in a competitive electricity market. The most probable scenarios of the electricity innovative development and the electricity market structure changes have been outlined. A study of technology foresight methods that allow developing parametric models of the technological industry development has been undertaken.

In the absence of an effective technological possibility for the storage of electricity in industrial volumes, consumption and production of electrical energy are carried out simultaneously. The ability to generate cover the unevenness of the daily schedule of consumption provides a balance of power system parts, leads to the minimization of network infrastructure costs. This article represents the analysis of the results for balancing certain parts of the UPS Russia, based on the methodological approach described below. Volume of "basic" electrical energy consumption specifies requirements for the structure of generating capacity. Reducing the share of "basic" consumers, including by the construction of its own "base" generation, leads either to an increase in the depth of discharge of generating capacities in the power system, or to the necessary shutdowns of generating equipment at night. Performed calculations showed non-optimal placement of the "base" generation in the Russian Federation. The proposed method allows you to determine the presence and absence of the adjustment range in the power system as a whole or in its individual parts, avoid errors in the placement of generating capacity in the Russian Federation, including nuclear power plants, heat supply units, "green" generation, optimize the cost for the construction of the network infrastructure.

The paper is concerned with an integrated system of internal combustion engine and mini combined heat and power plant (ICE-CHP). The system is based on multi-stage wood biomass gasification. The use of producer gas in the system affects negatively the internal combustion engine performance and, therefore, reduces the efficiency of the ICE-CHP plant. A mathematical model of an internal combustion engine running on low-calorie producer gas was developed using an overview of Russian and foreign manufacturers of reciprocating units, that was made in the research. A thermal calculation was done for four-stroke gas engines of different rated power outputs (30, 100 and 250 kW), running on producer gas (CO₂ – 10.2, CO – 45.8, N₂ – 38.8%). Thermal calculation demonstrates that the engine exhaust gas temperature reaches 500 – 600°C at the rated power level and with the lower engine power, the temperature gets higher. For example, for an internal combustion engine power of 1000 kW the temperature of exhaust gases equals 400°C. A comparison of the efficiency of engine operation on natural gas and producer gas shows that with the use of producer gas the power output declines from 300 to 250 kW_e. The reduction in the effective efficiency in this case makes up 2%. The measures are proposed to upgrade the internal combustion engine to enable it to run on low-calorie producer gas.

Despite existing issues related to durability and convenience of operation plate heat exchangers are more and more often used in various industries, from the housing and utilities sector to nuclear power. One little-known peculiarity of plate heat exchangers is breathing effect. This effect takes place when pressures of heat exchanging mediums are not equal. Pressure difference between adjacent channels makes channels with lower pressure to narrow and channels with higher pressure to extend. This peculiarity of plate heat exchangers is not advertised and thermal-hydraulic calculations often ignore it. However, this effect can increase the hydraulic resistance of the heat exchanger up to 3.5 times. Given the sufficiently high hydraulic resistance of the plate heat exchangers, its significant increase can affect the functional characteristics of the heat exchanger negatively. Therefore, in thermal-hydraulic calculations it is necessary to take account of breathing effect. In this paper, we consider available experimental data, analyze the factors causing breathing effect and propose measures to minimize it.

There are almost no experimental data on the head-capacity curves for liquid-jet compressors with the inlet gas pressure of liquid-jet apparatus more than 1 MPa. Meanwhile, this range is important for many engineering applications in which relatively low compressor ratio is required for the pumping of gas under high pressure. This is mostly the case when gas circulation is to be provided in a closed or almost closed circuit. A head-capacity curve of a liquid-jet apparatus has been estimated experimentally for the air pumping at up to 2.5 MPa by a water jet. To obtain this curve, a new original technique has been submitted and verified which is based on an inverse unsteady problem of gas pumping and allows derivation of the whole curve instead of one operating point, which is the case for conventional methods. The experiments have demonstrated that the relative head of the liquid-jet compressor grows with the apparatus inlet air pressure in the middle part of the curve.

The exit-gas temperature behind the recovery boiler depends on the location, climate conditions, operation modes of the gas and steam turbine equipment at the combined-cycle cogeneration plant and can be slightly higher than the minimum admissible value. It leads to emergence of additional of exit-gas heat behind the recovery boiler. However the high-grade heat of the steam turbine extraction not only for own flows needs but also system water is used for heating. It reduces profitability of work of all power plants. The ways of use of the additional of the exit-gas heat behind the recovery boiler system water heating and chemically treated water of district heating makeup heating are offered. It leads to production the extra power by steam turbine and to improve the efficiency of binary combined-cycle cogeneration plant operation.

In the present article researches of statistical material on the refusals and malfunctions influencing operability of heat power installations have been conducted. In this article the mathematical model of change of output characteristics of the turbine depending on number of the refusals revealed in use has been presented. The mathematical model is based on methods of mathematical statistics, probability theory and methods of matrix calculation. The novelty of this model is that it allows to predict the change of the output characteristic in time, and the operating influences have been presented in an explicit form. As desirable dynamics of change of the output characteristic (function, reliability) the law of distribution of Veybull which is universal is adopted since at various values of parameters it turns into other types of distributions (for example, exponential, normal, etc.) It should be noted that the choice of the desirable law of management allows to determine the necessary management parameters with use of the saved-up change of the output characteristic in general. The output characteristic can be changed both on the speed of change of management parameters, and on acceleration of change of management parameters. In this article the technique of an assessment of the pseudo-return matrix has been stated in detail by the method of the smallest squares and the standard Microsoft Excel functions. Also the technique of finding of the operating effects when finding restrictions both for the output characteristic, and on management parameters has been considered. In the article the order and the sequence of finding of management parameters has been stated. A concrete example of finding of the operating effects in the course of long-term operation of turbines has been shown.

We put quite a difficult task maintaining a temperature drop to 11-12 degrees at thermal power plants to ensure the required depth of cooling of vacuum in the condenser, cooling towers. This requirement is achieved with the reducing of the hydraulic load with the low efficiency of the apparatus. The task analysis process in this unit and identify the causes of his poor performance was put in the work. One of the possible reasons may be the heterogeneity of the process in the volume of the apparatus. Therefore, it was decided to investigate experimentally the distribution of the irrigation water and the air flow in the cross section of industrial cooling towers. As a result, we found a significant uneven distribution of flows of water and air in the volume of the apparatus. We have shown theoretically that the uneven distribution of irrigation leads to a significant decrease in the efficiency of evaporation in the cooling tower. The velocity distribution of the air as the tower sections, and inside sections are interesting. The obtained experimental data allowed to establish the internal communication: the effects of the distributions of the density of irrigation in sections of the apparatus for the distribution of changes of the temperature and the air velocity. The obtained results allowed to formulate a methodology for determining process problems and to develop actions on increase of the efficiency of the cooling tower.

At the stage of pre-proposals unit of the thermal power plants for regions with a hot climate requires a design study on the efficiency of possible options for the structure of the thermal circuit and a set of key parameters. In this paper, the thermal circuit of the condensing unit powerfully 350 MW. The main feature of the external conditions of thermal power plants in hot climates is the elevated temperature of cooling water of the turbine condensers. For example, in the Persian Gulf region as the cooling water is sea water. In the hot season of the year weighted average sea water temperature of 30.9 °C and during the cold season to 22.8 °C. From the turbine part of the steam is supplied to the distillation-desalination plant. In the hot season of the year heat scheme with pressure fresh pair of 23.54 MPa, temperature 570/560 °C and feed pump with electric drive (EDP) is characterized by a efficiency net of 0.25% higher than thermal schem with feed turbine pump (TDP). However, the supplied power unit with PED is less by 11.6 MW. Calculations of thermal schemes in all seasons of the year allowed us to determine the difference in the profit margin of units of the TDP and EDP. During the year the unit with the TDP provides the ability to obtain the profit margin by 1.55 million dollars more than the unit EDP. When using on the market subsidized price of electricity (Iran) marginal profit of a unit with TDP more at 7.25 million dollars.

Electricity, heating and cooling are the three main components that make up the energy consumption base in residential, commercial and public buildings around the world. Demand for energy and fuel costs are constantly growing. Combined cooling, heating and power generation or trigeneration can be a promising solution to such a problem, providing an efficient, reliable, flexible, competitive and less harmful alternative to existing heat and cold supply systems. In this paper, scheme of the tri-generation plant on non-aqueous working substances is considered as an installation of a locally centralized electro-heat and cold supply of a typical residential house in a hot climate. The scheme of the combined installation of electro-heat (cold) supply consisted of the vapor power plant and heat pump system on low-boiling working substance for local consumers under the climatic conditions of Iraq is presented. The possibility of using different working substances in the thermodynamic cycles of these units, which will provide better efficiency of such tri-generation systems is shown. The calculations of steam turbine cycles and heat pump part on the selected working substances are conducted. It is proposed to use heat exchangers of plate type as the main exchangers in the combined processing. The developed method of thermal-hydraulic calculation of heat exchangers implemented in MathCad, which allows to evaluate the efficiency of plants of this type using the ε - NTU method. For the selected working substances of the steam part the optimal temperature of heat supply to the steam generator is determined. The results of thermodynamic and technical-economic analysis of the application of various working substances in the "organic" Rankine cycle of the steam turbine unit and the heat pump system of the heat and cold supply system are presented.

In the article, the issues of operational flexibility improvement for CCGT with a triple-pressure heat recovery steam generator are described. The factors limiting the operational range of CCGT were identified and analyzed. Analytical dependences for the minimum and maximum load of the CCGT on the ambient air temperature were obtained. The ways of expanding an operational range due to water spray into air-intake path, supplementary firing before the heat recovery steam generator, intensifying regulation of compressor airflow using the IGV and its pre-heating are described.

The issue of the choice of the working fluids for power plants, operating on the basis of (according to the foreign literature sources) the Organic Rankine Cycle – ORC – has multifactorial character, which is first of all imposed by famous international (Montreal, Kyoto, Paris) ozone-hazardous freons application prohibition and greenhouse emissions control agreements. At the analysis of different working fluids implementation prospects also the ecological and technological safety issue has a paramount importance. When all mentioned above factors are taken into account the chosen fluids thermodynamic efficiency and thermal stability issue comes to the fore. The authors justify the use of organofluorine it working substances, is formulated and confirmed by a number of their advantages.

Application on the Central heat source (CHS) local generation of electricity is primarily aimed at solving problems of own needs of electric energy that not only guarantees the independence of the work of the CHS from external electrical networks, but will prevent the stop of heat supply of consumers and defrosting heating networks in case of accidents in electrical networks caused by natural or anthropogenic factors. Open the prospects of electric power supply stand-alone objects, such commercial or industrial objects on the territory of a particular neighborhood.

Direct three-dimensional printing is a new manufacturing method that can improve the efficiency of the energy equipment. Additive manufacturing allow reduce the weight of products, to increase the toughness, to improve the shape of parts, reduce the number of components, etc. An example of a new approach to the design is the improvement of heat exchanges for which it is possible to use new materials, increase in the area of heat transfer, make turbulators create items, create heat exchanger as a single part, etc. The actual problem is the improvement of pipeline systems through the reduction of local hydraulic resistance. Additive manufacturing are used for the development of new turbomachinery with complex cooling channels. Moreover, the advantage of additive manufacturing is full integration in PLM digital interface. However, the revolutionary new Design for Additive Manufacturing (DFAM) approach must be developed.

Heat exchangers of various types (gas-gas, gas-liquid, liquid-liquid) are widely used in power plants of thermal power plants and nuclear power plants. Like any technical system, the heat exchange apparatus is estimated by the main quality indicator-energy efficiency. At present, most of the studies devoted to this issue are related to the determination of the intensification of the heat transfer process and the determination of the energy efficiency of convective heating surfaces. At the same time, both at the design stage, and especially for the functioning heat exchanger, it is required to determine its energy efficiency (further energy efficiency), which usually decreases with time. It is necessary to distinguish between the energy efficiency of the heat exchanger as a whole, in which the heat transfer occurs in the case of two-sided flow around the heat exchange surface and the energy efficiency of the surface on each side. (In the case of a heat exchanger with one-sided flow around the heat transfer surface, these concepts are often assumed to be identical, which is far from always correct). At the same time, after increasing the energy efficiency of the heat exchanger, due to the justified introduction of design changes, it is necessary to carry out a technical and economic calculation showing the means and time spent on the modernization of the apparatus. In the present paper, the existing design methods for increasing energy efficiency in low-pressure heaters of the PN-1100-25-6-1 type are considered and one of the promising ones is selected. The technical and economic calculation of this heater has been completed

The comparative feasibility study of the energy storage technologies showed good applicability of hydrogen-oxygen steam generators (HOSG) based energy storage systems with large-scale hydrogen production. The developed scheme solutions for the use of HOSGs for thermal power (TPP) and nuclear power plants (NPP), and the feasibility analysis that have been carried out have shown that their use makes it possible to increase the maneuverability of steam turbines and provide backup power supply in the event of failure of the main steam generating equipment. The main design solutions for the integration of hydrogen-oxygen steam generators into the main power equipment of TPPs and NPPs, as well as their optimal operation modes, are considered.

Over the past 3 years there have been significant changes in Russian environmental legislation related to the transition to technological regulation based on the principles of the best available technologies (BAT). These changes also imply control and accounting of the harmful impact of industrial enterprises on the environment. Therefore, a mandatory requirement for equipping automatic continuous emission monitoring systems (ACEMS) is established for all large TPPs. For a successful practical solution of the problem of introducing such systems in the whole country there is an urgent need to develop the governing regulatory document for the design and operation of systems for continuous monitoring of TPP emissions into the air, allowing within reasonable limits to unify these systems for their work with the state data fund of state environmental monitoring and make easier the process of their implementation at operating facilities for industrial enterprises. Based on the large amount of research in the field of creation of ACEMS, which conducted in National Research University "MPEI", a draft guidance document was developed, which includes the following regulatory provisions: goals and objectives of ACEMS, the stages of their introduction rules of carrying out preliminary inspection of energy facilities, requirements to develop technical specifications, general requirements for the operation of ACEMS, requirements to the structure and elements of ACEMS, recommendations on selection of places of measuring equipment installation, rules for execution, commissioning and acceptance testing, continuous measurement method, method for determination of the current gross and specific emissions. The draft guidance document, developed by the National Research University "MPEI", formed the basis of the Preliminary national standards PNST 187-2017 "Automatic systems for continuous control and metering of contaminants emissions from thermal electric power stations into the atmospheric air. General requirements". [1]

The problem of enhancing energy and economic efficiency of CP is urgent indeed. One of the main methods for solving it is optimization of CP operation. To solve the optimization problems of CP operation, Energy Systems Institute, SB of RAS, has developed a software. The software makes it possible to make optimization calculations of CP operation. The software is based on the techniques and software tools of mathematical modeling and optimization of heat and power installations. Detailed mathematical models of new equipment have been developed in the work. They describe sufficiently accurately the processes that occur in the installations. The developed models include steam turbine models (based on the checking calculation) which take account of all steam turbine compartments and regeneration system. They also enable one to make calculations with regenerative heaters disconnected. The software for mathematical modeling of equipment and optimization of CP operation has been developed. It is based on the technique for optimization of CP operating conditions in the form of software tools and integrates them in the common user interface. The optimization of CP operation often generates the need to determine the minimum and maximum possible total useful electricity capacity of the plant at set heat loads of consumers, i.e. it is necessary to determine the interval on which the CP capacity may vary. The software has been applied to optimize the operating conditions of the Novo-Irkutskaya CP of JSC "Irkutskenergo". The efficiency of operating condition optimization and the possibility for determination of CP energy characteristics that are necessary for optimization of power system operation are shown.

Domestic heat and power engineering needs means and methods for optimizing the existing boiler plants in order to increase their technical, economic and environmental work. The development of modern computer technology, methods of numerical modeling and specialized software greatly facilitates the solution of many emerging problems. CFD simulation allows to obtaine precise results of thermochemical and aerodynamic processes taking place in the furnace of boilers in order to optimize their operation modes and develop directions for their modernization.

The paper presents the results of simulation of the combustion process of a low-emission vortex coal boiler of the model E-220/100 using the software package Ansys Fluent. A hexahedral grid with a number of 2 million cells was constructed for the chosen boiler model. A stationary problem with a two-phase flow was solved. The gaseous components are air, combustion products and volatile substances. The solid phase is coal particles at different burnup stages. The Euler-Lagrange approach was taken as a basis. Calculation of the coal particles trajectories was carried out using the Discrete Phase Model which distribution of the size particle of coal dust was accounted for using the Rosin-Rammler equation. Partially Premixed combustion model was used as the combustion model which take into account elemental composition of the fuel and heat analysis. To take turbulence into account, a two-parameter k-ε model with a standard wall function was chosen. Heat transfer by radiation was calculated using the P1-approximation of the method of spherical harmonics. The system of spatial equations was numerically solved by the control volume method using the SIMPLE algorithm of Patankar and Spaulding.

Comparison of data obtained during the industrial-operational tests of low-emission vortex boilers with the results of mathematical modeling showed acceptable convergence of the tasks of this level, which confirms the adequacy of the realized mathematical model.

«Soot carbon» or «Soot» - incomplete combustion or thermal decomposition particulate carbon product of hydrocarbons consisting of particles of various shapes and sizes. Soot particles are harmful substances Class 2 and like a dust dispersed by wind for thousands of kilometers. Soot have more powerful negative factor than carbon dioxide. Therefore, more strict requirements on ecological and economical performance for energy facilities at Arctic areas have to be developed to protect fragile Arctic ecosystems and global climate change from degradation and destruction. Quantity of soot particles in the flue gases of energy facilities is a criterion of effectiveness for organization of the burning process. Some of heat generators do not provide the required energy and environmental efficiency which results in irrational use of energy resources and acute pollution of environment. The paper summarizes the results of experimental study of solid particles emission from wide range of capacity boilers burning different organic fuels (natural gas, fuel oil, coal and biofuels). Special attention is paid to environmental and energy performance of the biofuels combustion. Emissions of soot particles PM2.5 are listed. Structure, composition and dimensions of entrained particles with the use of electronic scanning microscope Zeiss SIGMA VP were also studied. The results reveal an impact of several factors on soot particles emission.

The refrigeration and air-conditioning industries are important sectors of the economy and represents about 15 % of global electricity consumptions. The chlorofluorocarbons also called CFCs are a class of refrigerants containing the halogens chlorine and/or fluorine on a carbon skeleton. Because of their environmental impact the Montreal Protocol was negotiated in 1987 to limit the production of certain CFCs and hydrochlirofluorocarbons (HCFCs) in developed and developing countries. The halogenated refrigerants are depleting the ozone layer also major contribution to the greenhouse effect. To be acceptable as a refrigerant a fluid must satisfy a variety of thermodynamic criteria and should be environment friendly with zero Ozone Depletion Potential and low Global Warming Potential. The perspective of a future phase down of HFCs is considered in this report taking into account a strategy for the phase out of HCFCs and perspective of choosing of various refrigerant followed by safety issues.

Wood and by-products of its processing are a renewable energy source with carbon neutral and may be used in solving energy problems. ZAO «Arkhangelsk plywood factory» installed and put into operation the boiler with capacity of 22 MW (saturated steam of 1.2 MPa) to reduce the cost of thermal energy, the impact of environmental factors on stability of the company's development and for reduction of harmful emissions into the environment. Fuel for boiler is the mixture consists of chip plywood, birch bark, wood sanding dust (WSD) and sawdust of the plywood processing. The components of the fuel mixture significantly differ in thermotechnical characteristics and technological parameters but especially in size composition. Particle dimensions in the fuel mixture differ by more than a thousand times which makes it «unique» and very difficult to ensure the effective and non-explosive use. WSD and sawdust from line of cutting of plywood are small fraction material and relate to IV group of explosion. Criterion of explosive for them has great values (К_f^WSD=10.85; К_f^saw=9.66). Boiler's furnace equipped with reciprocating grate where implemented a three-stage scheme of combustion. For a comprehensive survey of the effectiveness of installed equipment was analyzed the design features of the boiler, defined the components of thermal balance, studied nitrogen oxide emissions, carbon and particulate matter with the determination of soot emissions. Amount of solid particles depending on their shape and size was analyzed.

MPEI conducts researches on physical and mathematical models of furnace chambers for improvement of power-generation equipment fuel combustion efficiency and ecological safety. Results of these researches are general principles of furnace aerodynamics arrangement for straight-flow burners and various fuels. It has been shown, that staged combustion arrangement with early heating and igniting with torch distribution in all furnace volume allows to obtain low carbon in fly ash and nitrogen oxide emission and also to improve boiler operation reliability with expand load adjustment range. For solid fuel combustion efficiency improvement it is practical to use high-placed and strongly down-tilted straight-flow burners, which increases high-temperature zone residence time for fuel particles. In some cases, for this combustion scheme it is possible to avoid slag-tap removal (STR) combustion and to use Dry-bottom ash removal (DBAR) combustion with tolerable carbon in fly ash level. It is worth noting that boilers with STR have very high nitrogen oxide emission levels (1200-1800 mg/m³) and narrow load adjustment range, which is determined by liquid slag output stability, so most industrially-developed countries don't use this technology. Final decision about overhaul of boiler unit is made with regard to physical and mathematical modeling results for furnace and zonal thermal calculations for furnace and boiler as a whole.

Overhaul of boilers to provide staged combustion and straight-flow burners and nozzles allows ensuring regulatory nitrogen oxide emission levels and corresponding best available technology criteria, which is especially relevant due to changes in Russian environmental regulation.

The present work analyzes the effect of physical properties of liquid fuels with high viscosity (including biofuels) on the spray and burning characteristics. The study showed that the spray characteristics behind devices well atomized fuel oil, may significantly deteriorate when using biofuels, until the collapse of the fuel bubble. To avoid this phenomenon it is necessary to carry out the calculation of the fuel film form when designing the nozzles. As a result of this calculation boundary curves in the coordinates of the Reynolds number on fuel - the Laplace number are built, characterizing the transition from sheet breakup to spraying. It is shown that these curves are described by a power function with the same exponent for nozzles of various designs. The swirl of air surrounding the nozzle in the same direction, as the swirl of fuel film, can significantly improve the performance of atomization of highly viscous fuel. Moreover the value of the tangential air velocity has the determining influence on the film shape. For carrying out of hot tests in aviation combustor some embodiments of liquid fuels were proved and the most preferred one was chosen. Fire tests of combustion chamber compartment at conventional fuel has shown comprehensible characteristics, in particular wide side-altars of the stable combustion. The blended biofuel application makes worse combustion stability in comparison with kerosene. A number of measures was recommended to modernize the conventional combustors when using biofuels in gas turbine engines.

Development of a solid fuel ramjets requires mathematical modeling of the solid fuel regression inside a combustor with accounting of solid fuel gasification and combustion processes and a numerical method to calculate parameters of these processes. This report presents a quasi-one-dimensional model of processes inside the solid fuel ramjet combustor. The model allows to calculate the solid fuel regression rate and gas flow parameters at the combustor outlet while air flow parameters at the combustor inlet are fixed. The model is based on mass, energy, species and momentum conservation equations and deals with thermochemical processes inside the ramjet combustor. It considers gas flow inside the combustor, gasified fuel combustion, convective heat transfer, solid fuel pyrolysis kinetics. The model is verified by comparison of the numerical results with the experimental data available from other authors. The analysis of the numerical results shows a dependence of the flow structure and thermochemical parameters of a solid fuel employed on the regression rate.

The study on coal char ignition by CO₂-continuous laser was carried out. The coal char samples of T-grade bituminous coal and 2B-grade lignite were studied via CO₂-laser ignition setup. Ignition delay times were determined at ambient condition in heat flux density range 90–200 W/cm². The average ignition delay time value for lignite samples were 2 times lower while this difference is larger in high heat flux region and lower in low heat flux region. The kinetic constants for overall oxidation reaction were determined using analytic solution of simplified one-dimensional heat transfer equation with radiant heat transfer boundary condition. The activation energy for lignite char was found to be less than it is for bituminous coal char by approximately 20 %.

Experimental study results of a droplet ignition and combustion were obtained for coal-water slurry containing petrochemicals (CWSP) prepared from coal processing waste, low-grade coal and waste petroleum products. A comparative analysis of process characteristics were carried out in different conditions of fuel droplet interaction with heated air flow: droplet soars in air flow in a vortex combustion chamber, droplet soars in ascending air flow in a cone-shaped combustion chamber, and droplet is placed in a thermocouple junction and motionless in air flow. The size (initial radii) of CWSP droplet was varied in the range of 0.5–1.5 mm. The ignition delay time of fuel was determined by the intensity of the visible glow in the vicinity of the droplet during CWSP combustion. It was established (under similar conditions) that ignition delay time of CWSP droplets in the combustion chamber is lower in 2–3.5 times than similar characteristic in conditions of motionless droplet placed in a thermocouple junction. The average value of ignition delay time of CWSP droplet is 3–12 s in conditions of oxidizer temperature is 600–850 K. Obtained experimental results were explained by the influence of heat and mass transfer processes in the droplet vicinity on ignition characteristics in different conditions of CWSP droplet interaction with heated air flow. Experimental results are of interest for the development of combustion technology of promising fuel for thermal power engineering.

This paper presents the results of study on determination of degree and nature of influence of operating conditions of burner units and flare geometric parameters on the heat transfer in a combustion chamber of the fire-tube boilers. Change in values of the outlet gas temperature, the radiant and convective specific heat flow rate with appropriate modification of an expansion angle and a flare length was determined using Ansys CFX software package. Difference between values of total heat flow and bulk temperature of gases at the flue tube outlet calculated using the known methods for thermal calculation and defined during the mathematical simulation was determined. Shortcomings of used calculation methods based on the results of a study conducted were identified and areas for their improvement were outlined.

The experimental and theoretical study of combustion products has been carried out for the conditions of pulverized peat combustion in BKZ-210-140F steam boiler. Sampling has been performed in different parts of the boiler system in order to determine the chemical composition, radiative properties and dispersity of slag and ash particles. The chemical composition of particles was determined using the method of x-ray fluorescence analysis. Shapes and sizes of the particles were determined by means of electron scanning microscopy. The histograms and the particle size distribution functions were computed. The calculation of components of the gaseous phase was based on the combustion characteristics of the original fuel. The software package of calculation of thermal radiation of combustion products from peat combustion was used to simulate emission characteristics (flux densities and emissivity factors). The dependence of emission characteristics on the temperature level and on the wavelength has been defined. On the basis of the analysis of emission characteristics the authors give some recommendations how to determine the temperature of peat combustion products in the furnace of BKZ-210-140F steam boiler. The findings can be used to measure the combustion products temperature, support temperature control in peat combustion and solve the problem of boiler furnace slagging.

All articles must contain an abstract. The abstract text should be formatted using 10 point Times or Times New Roman and indented 25 mm from the left margin. Leave 10 mm space after the abstract before you begin the main text of your article, starting on the same page as the abstract. The abstract should give readers concise information about the content of the article and indicate the main results obtained and conclusions drawn. The abstract is not part of the text and should be complete in itself; no table numbers, figure numbers, references or displayed mathematical expressions should be included. It should be suitable for direct inclusion in abstracting services and should not normally exceed 200 words in a single paragraph. Since contemporary information-retrieval systems rely heavily on the content of titles and abstracts to identify relevant articles in literature searches, great care should be taken in constructing both.

The paper is devoted to numerical investigation on combustion singularities of the bi-dispersed coal-dust methane-air mixture in a slot recuperative burner. The aim of the research is to determine the stable combustion conditions of the methane-air mixture depending on the fuel flow rate at the inlet of the burner and on the parameters of the mixture (the particle size and the mass concentration of the coal particles, the percentage composition of inert particles and the methane volume content). The problem was solved by finite difference method. The regimes of stable combustion for the coal-dust methane-air mixture depending on the fuel content and the fuel flow rate at the inlet of the burner the have been defined.

Single-stage fuel gasification processes have been developed and widely studied in Russia and abroad throughout the 20th century. They are fundamental to the creation and design of modern gas generator equipment. Many studies have shown that single-stage gasification process, have already reached the limit of perfection, which was a significant improvement in their performance becomes impossible and unprofitable.

The most fully meet modern technical requirements of multistage gasification technology. In the first step of the process, is organized allothermic biomass pyrolysis using heat of exhaust gas and generating power plant. At this stage, the yield of volatile products (gas and tar) of fuel. In the second step, the layer of fuel is, the tar is decomposed by the action of hot air and steam, steam-gas mixture is formed further reacts with the charcoal in the third process stage. The paper presents a model developed by the authors of the multi-stage gasifier for wood chips. The model is made with the use of CFD-modeling software package (COMSOL Multiphisics). To describe the kinetics of wood pyrolysis and gasification of charcoal studies were carried out using a set of simultaneous thermal analysis. For this complex developed original methods of interpretation of measurements, including methods of technical analysis of fuels and determine the parameters of the detailed kinetics and mechanism of pyrolysis.

There are two groups of atmosphere protecting measures: technology (primary) and treatment (secondary). When burning high-calorie low-volatile brands of coals in the furnaces with liquid slag removal to achieve emission standards required joint use of these two methods, for example, staged combustion and selective non-catalytic reduction recovery (SNCR). For the economically intelligent combination of these two methods it is necessary to have information not only about the environmental performance of each method, but also the operating costs per unit of reduced emission. The authors of this report are made an environmental-economic analysis of SNCR on boiler Π-50P Kashirskaya power station. The obtained results about the dependence of costs from the load of the boiler and the mass emissions of nitrogen oxides then approximates into empirical formulas, is named as environmental and economic characteristics, which is suitable for downloading into controllers and other control devices for subsequent implementation of optimal control of emissions to ensure compliance with environmental regulations at the lowest cost at any load of the boiler.

The analysis of the trial-industrial research of the effectiveness of burning water fuel mixtures in steam boilers of medium and high pressure at the combustion of natural gas and fuel oil is carried out. As a result of a research decrease in nitrogen oxide concentration is depending on the amount of moisture pumped to the boilers and type of the incinerated fuel. The theoretical model of the formation of nitrogen oxides in the furnace of the boiler in order to optimize the combustion process with the introduction of moisture, whereby to determine the concentrations of nitrogen oxides formed in the combustion process of the method of expansion of the exponential is received. The dependences of the maximal temperature of a torch, reaction rate of formation of nitrogen oxides, the conditional time of reaction, theoretical concentration of nitrogen oxides taking into account input of moisture in a fire chamber of a copper and coefficient of an exit of nitrogen oxides are defined at combustion of fuel taking into account moisture input. The divergence between the experimental and the theoretical value of the NO_x concentration does not exceed 3.8%. The methodical provisions of the economic assessment of concentrations of pollutants reduction when entering the water are drafted. The rate the net present value (NPV) is applied. The optimal water-fuel ratio is selected based on the maximum value of the net present value (NPV). The evaluation of the application of environmental protection measures carried out taking into account the fact that by reducing the emission values in the implementation of this activity will decrease the amount of payment for emissions of polluting substances, which are collected from the profits of the enterprise. The cost estimate for the implementation of environmental activities carried out on the basis of lump-sum costs and current costs in environmental technology (increased fuel and water consumption).

In this paper, we propose to use the slag and ash material of thermal power plants (TPP) operating on pulverized coal fuel. The elemental and chemical composition of fly ash of five Kuzbass thermal power plants differs insignificantly from the composition of the mineral part of coking coal because coke production uses a charge, whose composition defines the main task: obtaining coke with the required parameters for production of iron and steel. These indicators are as follows: CRI reactivity and strength of the coke residue after reaction with CO₂ – CSR. The chemical composition of fly ash of thermal power plants and microsilica with bulk density of 0.3-0.6 t/m³ generated at production of ferroalloys was compared. Fly ash and microsilica are the valuable raw material for production of mineral binder in manufacturing coke breeze briquettes (fraction of 2-10 mm) and dust (0-200 μm), generated in large quantities during coking (up to 40wt%). It is shown that this binder is necessary for production of smokeless briquettes with low reactivity, high strength and cost, demanded for production of cupola iron and melting the silicate materials, basaltic rocks in low-shaft furnaces. It is determined that microsilica contains up to 90% of silicon oxide, and fly ash contains up to 60% of silicon oxide and aluminum oxide of up to 20%. On average, the rest of fly ash composition consists of basic oxides. According to calculation by the VUKHIN formula, the basicity index of briquette changes significantly, when fly ash is introduced into briquette raw material component as a binder. The technology of coke briquette production on the basis of the non-magnetic fraction of TPP fly ash in the ratio from 3.5:1 to 4.5:1 (coke breeze : coke dust) with the addition of the binder component to 10% is proposed. The produced briquettes meet the requirements by CRI and require further study on CSR requirements.

Nowadays the problem of improvement of pulverized coal combustion schemes is an actual one for national power engineering, especially for combustion of coals with low milling fineness with significant portion of moisture or mineral impurities. In this case a big portion of inert material in the fuel may cause impairment of its ignition and combustion. In addition there are a lot of boiler installations on which nitrogen oxides emission exceeds standard values significantly. Decreasing of milling fineness is not without interest as a way of lowering an electric energy consumption for pulverization, which can reach 30% of power plant's auxiliary consumption of electricity. Development of a combustion scheme meeting the requirements both for effective coal burning and environmental measures (related to NO_x emission) is a complex task and demands compromising between these two factors, because implementation of NO_x control by combustion very often leads to rising of carbon-in-ash loss. However widespread occurrence of such modern research technique as computer modeling allows to conduct big amount of variants calculations of combustion schemes with low cost and find an optimum. This paper presents results of numerical research of combined schemes of coal combustion with high portion of inert material based on straight-flow burners and nozzles. Several distinctive features of furnace aerodynamics, heat transfer and combustion has been found. The combined scheme of high-ash bituminouos coals combustion with low milling fineness, which allows effective combustion of pointed type of fuels with nitrogen oxides emission reduction has been proposed.

The ignition and burning of monodisperse and two-fraction suspensions of carbon particles at gas temperature in the range 1100 ÷ 1500 K are modeled. The critical gas temperature of the suspension ignition, the particles ignition delay and burning time, the burning temperature, and the extinction parameters are determined. The data obtained are compared with burning characteristics of single particle of equal size. The ignition temperatures of the fine fraction (the particle diameter 60 μm) and the coarse one (120 μm) are practically the same. The ignition temperatures of the equivalent single particles are much higher and they differ by 100 K and more. The gas temperature is found below which the ignition delay of the fine fraction exceeds the one of the coarse fraction. It is found that, at critical ignition temperatures the burning temperature of the fine fraction is lower than that of the coarse fraction. At gas temperatures above 1250 K, the burning temperature of the fine fraction is higher. It is established that, in contrast to single particles, the temperature difference between the particles and the gas is small during gas-suspension extinction. Further oxidation of the particles occurs in the kinetic regime, so it is possible to estimate the time of their complete conversion.

The investigation of the oil shale pyrolysis with a solid heat carrier was carried out using the experimental retorting system that simulates the Galoter industrial process. This system allows verifying both fractional composition of the oil shale and solid heat carrier, and their ratio and temperature. The oil shale of the Leningradsky deposit was used in the work, and quartz sand was used as the solid heat carrier. It is shown that the yield of the shale oil under the pyrolysis with solid heat carrier exceeds by more than 20% the results received in the standard Fisher retort. Using ash as the solid heat carrier results in a decrease in the yield of oil and gas with simultaneous increase in the amount of the solid residue. This is due to the chemical interaction of the acid components of the vapor-gas mixture with the oxides of alkaline-earth metals that are part of the ash.

Development of advanced oil shale processing technologies for production of liquid and gaseous fuels, as well as chemical raw materials, is a very topical problem. The article provides information on commercially implemented oil shale thermal processing technologies which use gaseous (Fushun, Kiviter and Petrosix) and solid (Lurgi-Ruhrgas, Tosco II, Aostra-Tasiyuk, Galoter) heat carriers. The authors note that the Galoter process implemented in plants with solid heat carriers has significant advantages compared to other processes.