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Increasing the efficiency of using fossil fuels at thermal power plants is an urgent task. This problem arises most acutely during the operation of pulverized coal power boilers using flare fuel combustion technologies. The purpose of this work is an experimental and computational study and justification of the technology of low-temperature combustion of coal in a combustion chamber with a vertical precessing vortex and the creation of a prototype combustion chamber for a power steam boiler. To achieve this goal, a study of the process of two-stage coal combustion was carried out, when the first stage of coal combustion is carried out in a pre-furnace with a fluidized bed, and the after-combustion of the products of incomplete combustion of coal is carried out with gas illumination in an after-combustion chamber with a vertical precessing vortex. The relationship between the main design parameters of the combustion chamber and the main operating characteristics of the diffusion vortex has been determined. The most important results are: development and experimental validation of the parameters of the combustion chamber with a vertical precessing vortex; determination of optimal operating modes of the furnace when burning coal and combined combustion of coal and gas; creation of a prototype furnace for a power steam boiler with natural circulation, operating on Kansk-Achinsk coal. The significance of the results obtained lies in the possibility of their use in the design of new or modernization of existing power boilers in order to increase the efficiency, reliability and environmental safety of operation.

Topics related to fuel combustion and its impact on the environment will never lose their relevance, as the issues of efficient combustion and emission reduction are key in power generation and environmental protection. The countries of the European Union are massively abandoning the use of natural gas as a fuel for thermal power stations. However, in Asian countries, the ease of using natural gas as the main fuel and its environmental friendliness compared to coal made it possible to widely use natural gas in industry and energy sector. Comparing natural gas with alternative combustible gases (generator, blast furnace, mine, biogas), the main conclusion that it has the most attractive characteristics for its use in industry, including energy facilities, can be drawn. Therefore, it is impossible to replace it with alternative fuels in the chemical, heavy industry and energy sector in the near future. The paper is devoted to CFD modeling of stabilized combustion without premixing in a burner with low swirl for two operating modes of the boiler unit - nominal one and at 60% capacity. The study was carried out using numerical methods with the ANSYS-Fluent application program package. The object of the study is a burner built according to the technology based on the use of jet-niche systems with gas distribution of fuel by circular jets fed perpendicularly into the flow of the oxidizer through a single-row system of holes. Hydrodynamics and heat exchange processes were chosen as the subject of research, based on the analysis of which a model of NOx generation in jet-niche systems was obtained. The authors of the paper believe that replacing the regular burners of the DKVR-10-13 water heating boiler with a jet-niche ones can contribute to better mixing of fuel and air and ensure more complete combustion. In this paper, two types of burners are considered. In one of the burners, fuel is supplied through rectangular slits, in the other – through round holes arranged in a row. Air is supplied to both burners through rectangular slits. It was determined that gas distribution through round holes increases the spraying of the mixture and increases the area of combustion products spraying. Visualization of the distribution of pressure, temperature, kinetic energy profiles of turbulent pulsations and vorticity was carried out. The obtained results indicate that there are no changes in the flow regime, flame displacement or its instability. It was determined that both the axial velocity and the tangential velocity of the flow affect the distribution of combustion products and harmful impurities such as NOx. Gas distribution in circular jets stabilizes combustion and reduces flame expansion.

Producing powder compositions using conventional processing technology can lead to the formation of large agglomerates and, therefore, makes it difficult to obtain a uniform microstructure. The production of composites by self-propagating high-temperature synthesis can reduce costs and the number of technological stages, as well as lead to obtaining composites that are more homogeneous. Synthesis by the combustion of mixtures of powder reagents of sodium azide (NaN3), fluoroplastic (C2F4), aluminum and titanium with different ratios of reagents in a nitrogen gas atmosphere at a pressure of 4 MPa was used for the production of a highly dispersed powder ceramic AlN–TiC composition. Thermodynamic calculations have confirmed the possibility of synthesis of AlN–TiC compositions of different formulations in combustion mode. The dependences of temperature and combustion rate on the composition of the initial mixtures of reagents were experimentally determined for all stoichiometric reaction equations. The study have shown that the experimentally found dependences of combustion parameters on the ratio of the initial components correspond to the theoretical results of thermodynamic calculations. The formulation of the synthesized composition differs from the theoretical composition by a lower content of target phases and the formation of Al2O3, Na3AlF6 and TiO2 side phases. The powder composition consists of aluminum nitride fibers with a diameter of 100–250 nm and ultradisperse particles of predominantly equiaxed and lamellar shapes with a particle size of 200–600 nm. As the combustion temperature increases to produce the largest amount of titanium carbide phase, the particle size increases to the micron level.

The paper highlights advantages of using furnaces for processing vegetable waste, including the absence of condensation, minimal ash production, stable coolant temperature, and efficient heat exchange. To improve this machine and intensify the drying process, it is necessary to gather data on the heat and mass transfer characteristics during high-temperature drying of moisture-laden particles. Due to the inherent challenges of studying the drying process in a real furnace, the experiment was conducted using an isothermal (cold) model under laboratory conditions closely resembling real-world processes. (Research purpose) The research aims to assess the effectiveness of the proposed aerodynamic models for drying plant waste and validate the mathematical model for drying particles in a suspended bed. (Materials and methods) The study employs two suspended bed models with distinct vortex flow aerodynamics (flare and cyclone) in combustion chambers. The study investigates the drying kinetics of two specific fractions of sunflower husks, each with an equivalent particle diameter of 0.25 and 1.5 millimeters, and initial moisture levels of 15 and 18 percent. At various time intervals, measurements were taken for both the temperature and humidity of the husk particles, in addition to recording the temperature and relative humidity of the drying agent as it exited. The drying process operated in a cyclical mode. (Results and discussion) When the sunflower husk particles had an initial moisture content of 15 percent, two phases of increasing drying rates were observed, while at an 18 percent moisture content, three such periods were identified, with the first period displaying a constant rate. The results suggest that when the husks start with an initial moisture content of 15 percent, the drying curves exhibit minimal linear segments. This observation implies that the process is occurring as the drying rate decreases. (Conclusions) The experiment reveals the most effective drying mode in terms of intensity. It becomes evident that both the flarevortex and cyclone-vortex aerodynamic modes facilitate particle drying, with the cyclone-vortex mode delivering a notably more intense drying process. When transitioning from a model to a real-world process, it is essential to undertake a comparison of estimated processes with practical operational conditions, as exemplified by the particle drying model in a suspended bed.

The paper presents the results of laboratory experiments to study the parameters of the gas environment during the combustion of wood, rubber and plastic under conditions that exclude oxygen access to the reaction area. A laboratory bench has been developed to create the conditions. Graphs of temperature changes and reduction of light transmission of combustion products accumulated in the upper part of the combustion chamber layer have been obtained. Changes of the controlled parameters are analysed and correlation dependences between them are obtained. The results obtained can be used as estimates for building prediction models of fire development in enclosed storage rooms, as well as for assessing the fire hazard of substances when burning in an enclosed volume.

Background. The increase in the number of publications on the production and use of coal-water suspensions is due to the global increase in energy consumption, rising energy prices, as well as the needs to expand the fuel base in modern energy. On the other hand, interest in this area is associated with the issues of disposal of accumulated coal waste. In this regard, the task of systematizing and classifying the approaches proposed by various authors in the field of effective use of coal-water suspensions and coal-water fuel becomes urgent. Materials and methods. This paper presents an analysis of publications using modern methods of statistical and semantic analysis of big data. Results and conclusions. In particular, based on frequency analysis data, latent trends in the field of research related to coal-water fuel have been identified, methods for recycling water-coal fuel, and factors that determine the rheological properties of water-coal fuel have been identified. In addition, a classification of studies by type of coal was made.

The relevance of the work is determined by a wide interest in the technologies of pyrolysis of waste of various origin and the need to increase their effectiveness. Since pyrolysis liquid is an obligatory product of pyrolysis with yield up to 70 % of the mass of the raw material, its combustion is one of the essential conditions for maintaining the energy sufficiency of almost any technology. Problems with direct burning of such liquid are associated, majorly, with the instability of its properties and low calorific value. Its combustion in the mixture with traditional solid fuel allows leveling these shortcomings, which determines interest in the study on abovementioned processes. Purpose: determining the parameters of ignition and combustion of low reactivity coal mixtures with two different samples of pyrolysis liquids obtained at industrial pyrolysis enterprises, which use oil sludge and wood sawdust, as well as the identification of the relationships between the ignition parameters and the characteristics of fuel mixtures. Methods. Study on the properties of the component of used fuels was carried out using standard techniques. The oxidation parameters were determined by thermogravimetric analysis, and the data obtained were processed by the Coats–Redfern method. The characteristics of the ignition and combustion of fuel mixtures were determined using the experimental setup of fuel ignition in conditions similar to industrial equipment. Results. The properties of the studied low reactivity coal and two samples of pyrolysis liquid were determined, in particular, the values of the lower calorific value, ash content, as well as their elemental composition were determined. In the conditions of thermal analysis, the characteristics of the oxidation of the mixtures of low reactivity coal with pyrolysis liquids with a concentration of the latter equal to 5, 10 and 25 wt. % were investigated. It was established that the additive of pyrolysis oil did not lead to a significant change in the temperature ranges of the individual stages of the low reactivity coal oxidation, while the promotional effect of the additive was found, which consisted in a disproportionate reduction in the reaction rate compared to the composition of the fuel mixture. This conclusion was confirmed by a decrease in the value of activation energy for low reactivity coal as part of a mixture with pyrolysis oil. The addition of pyrolysis liquid also led to a decrease in the ignition delay time up to 65 %, while the maximum effect was achieved at 10 wt. % of the additive at 500 and 600 °C, and at 25 wt. % at 700 °C. A linear dependence of the ignition delay time on the lower calorific value was observed at 700 °C for mixtures of low reactivity coal with pyrolysis liquid from oil sludge and rubber waste. A similar relationship was observed between the activation energy for the mixture and the ignition delay time at 600 and 700 ° C for all considered pyrolysis liquids.

The relevance of the research is caused by the need for accurate reproduction of experimental measurements by mathematical models, since numerical simulation is widely used both for the development of new technologies for the combustion of solid fuels and for the modernization of existing boiler units. And as it is known, the parameters of a pulverized coal flame predicted by numerical simulation directly depend on the way the combustion chemistry in a turbulent flow is modeled. The main aim of the research is to study the accuracy of reproduction of experimental measurements for four approaches to the numerical simulation of ignition and burnout of combustible components of pulverized coal fuel in a turbulent flow. Objects: temperatures, concentrations of gas components (CO2, O2, CO and NOx), axial and tangential velocity components inside the IFRF 2.4 MW furnace. Methods: comparison of experimentally measured parameters of a pulverized coal flame and those predicted by numerical simulation. Numerical simulation was performed using the ANSYS FLUENT software package. The combustion of coal dust in the furnace is modeled as a two-phase turbulent flow system consisting of gas and discrete phases. Results. Numerical modeling of the combustion of pulverized coal in a turbulent flow has been carried out using four different approaches: equilibrium chemistry models with one and two mixture fractions; model of «eddy dissipation» and its combination with the kinetic model of combustion. A comparative analysis of the simulation results with the experimentally measured parameters of a pulverized coal flame established that all the studied approaches to modeling the pulverized coal combustion in a turbulent flow demonstrate a fairly good agreement with the experimental data. The «eddy dissipation» model in combination with the combustion kinetic model has the advantage in accuracy, and the equilibrium chemistry model with one mixture fraction has the advantage in the time of solution convergence.

Introduction. Alternative fuels in IC-engines make it possible to reduce the harmful effects of exhaust gases on the environment without the use of expensive cleaning systems, diversify the fuel market, and reduce the consumption of non-renewable energy recourses, while research aimed at studying the use of alternative fuels makes it possible to find optimal options for replacing non-renewable raw materials. The purpose of the work is to study the effect of using ethanol in a standard tractor diesel engine with volumetric mixing and combustion from flare resulting from the autoignition of a rapeseed oil pilot portion and to optimize separate cyclic fuel deliveries to obtain maximum energy and environmental effect. Materials and Methods. The article deals with the description of the results of the use of rapeseed oil and ethanol in a serial tractor diesel engine of dimension 2F 10.5/12.0 with separate fuel injection directly into the combustion chamber. In the course of experimental studies, the working process was indicated by a piezo quartz pressure sensor installed in the cylinder head, fuel and air consumption were measured, and samples of exhaust gases to study the gas composition and determine the content of toxic components and smokiness were taken. Results. The exact ethanol and rapeseed oil delivery was determined; the values of the average effective pressure, the average temperature of gases in the cylinder, and active and full heat generation were obtained. It is shown that with an increase in the cyclic ethanol delivery, the proportion of heat from kinetic combustion increases, while the diesel process is characterized by an increase in the proportion of diffusion combustion when the load increases. The analysis of the processes inside the cylinder when the engine runs on ethanol and rapeseed oil in comparison with the traditional diesel process is carried out. Discussion and Conclusion. The use of rapeseed oil and ethanol can completely replace the traditional fuel of petroleum origin for an operating diesel engine by installing additional fuel equipment and modifying the head of cylinder block through mounting an additional nozzle. In this case, the environmental performance of the diesel engine improves significantly.

The paper presents the results of a detailed study of the process and products of combustion during self-propagating high-temperature synthesis (SHS) of ZnO zinc oxide powder from mixtures of such common reagents as oxidizer zinc nitrate and reducing agent (fuel) glycine, as well as the application of synthesized highly dispersed submicron and nanosized ZnO powder for the phenol photocatalytic decomposition under the action of ultraviolet irradiation. An aqueous solution of a mixture of reagents (the SHS-S process or Solution Combustion Synthesis – SCS) and the gel from a mixture of initial dry reagents formed when they were moistened due to hygroscopicity (the SHS-G process or Gel Combustion Synthesis – GCS) were combusted. The authors studied the phase and chemical compositions, the structure of the combustion product, and the effect of calcination in an oxidizing air medium and grinding in drum ball and planetary-centrifugal mills, as well as in mortar, on them and their photocatalythic activity. The study showed that calcination considerably increases the photocatalytic activity of combustion products due to a significant decrease in carbon impurity in the unburned fuel remains, and grinding in mills reduces the photocatalytic activity due to iron contamination and coarsening of ZnO particle agglomerates. The difference between the photocatalytic activity of the SHS-G and SHS-S products in the phenol decomposition is evident only at the initial stage of ultraviolet irradiation, after which this difference disappears. The authors discuss the direction of further research to increase significantly the photocatalytic activity of zinc oxide synthesized during combustion to use it effectively for the phenol decomposition under the action of visible light.

In the present paper, a single host phosphor for a white light emitting diode (W-LED) Sr3(VO4)2:Eu3+, prepared by the co-precipitation method and combustion one, has been reported. Formation of the compound was confirmed by studying the X-ray diffraction pattern. The photoluminescence (PL) properties were studied by fluorescence spectrophotometer F-7000. The Sr3(VO4)2:Eu3+ exhibited a broad emission band covering the entire visible region centered at 520 nm wavelength and a sharp peak at 613 nm, when excited by 350 nm. The excitation spectrum at 520 nm emission wavelength was found to be suitable for pc-W-LED application.

Introduction. In this scientific article a scheme of the no synergistic effect is observedion process is considered. It has been shown that to slow down or suppress the main process occurring in the condensed phase and determining the formation of gaseous fuel several methods can be used: addition of polymers with increased thermal stability; addition of nanoadditives that reduce the amount of gaseous degradation products; introducing nanoadditives that affect the heat capacity or thermal conductivity of the system, thus changing the thermophysical characteristics of the polymer material. At the same time reduced reaction speeds, occurring in the gas phase and supporting the combustion process, can be achieved through reduction of the concentration of combustible gases and inhibition of the reactions responsible for the branching of the combustion chain process. Methods and materials. The composition and physical properties of kaolin are given. Kaolin monocrystal is a two-layer aluminosilicate containing water of hydration and consisting of chemically bonded layers of silicon dioxide and hydrated alumina. Results and discussion. We have studied the dependence of the attenuation time of a PVC composition on a composition containing from 3 to 10% kaolin. The introduction of kaolin into the PVC compound has led to decrease of decay time from 4.5 to 1 seconds. The effect of the amount of plasticizer on the oxygen index has been studied. We used dibutoxyethyl adipate (DBEA) as a plasticizer. It has good polymer compatibility and is environmentally friendly. The possibility of reducing the content of dibutoxyethyl adipate in the basic formulation of the original plasticate I40-13A by increasing the amount of calcium carbonate was studied, then the performance properties of the resulting compositions were studied. The content of PVC and other components in the basic recipe remained unchanged. Analysis of the data showed that for plasticization of 62% wt PVC contained in I40-13A, 20% wt DBEA is sufficient, while the filler content can be increased at least twice. The oxygen index (OI) value at a component ratio of 20% DBEA + 13.56% CaCO3 increases by 4 OI units and becomes equal to 29.1%. The dependence of the oxygen index of PVC compound on the composition containing from 5 to 20% kaolin has been studied. The results showed that the oxygen index of plastic compound increases significantly with increasing kaolin content. The OI drops with a decrease in the amount of the introduced, and it remains unchanged with its increase. Thus, the optimal content is 15%. Conclusion. Thus, kaolin is a promising, inexpensive and environmentally friendly filler for PVC materials, which effectively reduces their combustibility. The same effect is achieved by increasing the content of calcium carbonate in the original PVC compound formulation. However, no synergistic effect was observed while mixing kaolin and an excess of calcium carbonate.

THE PURPOSE. To carry out mathematical modeling of interrelated physicochemical processes in radiation chambers of tubular furnaces of pyrolysis of hydrocarbons. Perform numerical calculations of heat and mass transfer in the furnace furnace chamber with a multi-tiered arrangement of wall burners on the side lined walls.METHODS. Using our own package of applied programs based on the numerical solution of a system of differential equations of energy conservation and equations of radiation gas dynamics, the fields of velocities and temperatures of natural gas combustion products in the radiation chamber of a hydrocarbon pyrolysis tubular furnace are calculated. Interrelated processes of natural gas combustion, radiant-convective heat transfer, and turbulent flow of flue gases take place in the radiation chamber. These processes are modeled by two-dimensional equations of the combustion model, energy transfer by radiation, and equations of motion. In the side walls of the radiation chamber on both sides in eight horizontal tiers there are wall burners in the amount of 128 pieces. Combustion products emerging from the nozzles of these burners create complex velocity and temperature fields in the chamber volume. Due to the radiation of flue gases, the smallest soot particles and hot lined walls of the radiation chamber, heat flows are formed to the tubular screen, where hydrocarbons are pyrolyzed to produce ethylene.RESULTS. As a result of calculations, the velocity fields, the temperature in the volume of the radiation chamber and the concentration of the main components of the combustion products were obtained. Local values of surface densities of radiant heat fluxes to reaction pipes for methane and propane pyrolysis furnaces are calculated. Comparisons of some of the results obtained with the readings of the devices of existing technological installations are carried out.CONCLUSION. Calculations show that the developed software package makes it possible to obtain realistic values of local velocities and temperatures in the radiation chambers of tube furnaces, surface densities of convective and radiant heat fluxes to boundary surfaces, and other thermal and gas-dynamic parameters in the furnace volume. With a multi-row arrangement of a large number of wall burners of low thermal power, a complex field of temperature and velocities of combustion products in the furnace volume is formed on the side walls of the radiation chamber of the furnace. At the same time, this arrangement of the burners ensures a fairly uniform distribution of heat flows over the surface of the tubular screen of the hydrocarbon pyrolysis furnace.

The relevance of the article is caused by the growing interest in biomass pyrolysis technologies to reduce the carbon footprint of its processing. To increase the economic and energy efficiency of these technological solutions, it is necessary to maximize the full use of all material and energy flows, one of which is the formation of liquid pyrolysis products (the so-called pyrolysis liquid or bio-oil). The main aim of the research is determination of technological solutions for the disposal of liquid pyrolysis products of woody biomass with the determination of the level of technical readiness. Methods: analytical literature review of literature data using materials from the RSCI, Scopus and Web of Science databases; the level of technical readiness was assessed according to the TRL scale. Results. The main methods of utilization of the pyrolysis liquid obtained as a result of slow pyrolysis of woody biomass were identified, classified and described. A review of technological solutions and research works in the field of disposal of liquid products of slow pyrolysis was made. The most common technologies for converting a pyrolysis liquid to obtain thermal and/or electrical energy were direct combustion in burners of boilers and heat generators, in the combustion chamber of gas turbine engines, gasification to produce synthesis gas, and the use in piston engines as fuel. Technologies for obtaining chemical products and substances were divided into simple (obtaining components for road construction, wood preservative, phenol-formaldehyde and saponified resins, etc.) and complex, requiring complex multistage processing. It was established that the energy application of this product has the highest level of technical readiness, while the chemical application technologies have the highest economic efficiency, despite the relatively low level of readiness. Commercial solutions for the disposal of pyrolysis fluid are available in the field of combustion in burners and diesel generators.

The relevance of the research is caused by the interest in ensuring the thermal costs of oil refining technologies at the expense of by-products (oil sludge), as well as the need to reduce harmful emissions of technological processes. The main aim is research of the possibility of burning the carbon residue obtained during steam gasification of oil sludge as part of a fuel composition with the addition of peat. Objects of the research are carbon residue of oil sludge obtained after steam gasification of oil sludge at 600 °C, and a fuel composition based on it with the addition of peat (25 wt. %). Methods. Thermotechnical characteristics of the studied samples are determined according to SS R 55661-2013, 33503-2015 and 55660-2013. Net calorific values of the peats were determined in the ABK-1 calorimeter (Russia), the elemental composition of the organic matter was determined using the analyzer Vario Micro Cube (Elementar, Germany). Particle size (СROS) was determined using a scanning electron microscope JSM-6000C (JEOL, Japan). The study of the combustion of the samples under consideration was carried out using the differential thermal analyzer STA 449 F3 Jupiter (Netzsch, Germany) and an experimental stand equipped with a high-speed video camera FASTCAM CA4 5 (Photron, USA). The characteristic melting temperatures of ash and its composition are determined according to the SS 2057-94 and the SS 10538-87, respectively. Results. The carbon residue has a calorific value exceeding peat and comparable to brown coals and a rather low ignition temperature (220 °C), which is due to a rather high content of volatile substances (Vdaf =64,3 %). However, high values of ash content (Ad=60 %) and sulfur content (Sdaf=4,3 %) indicate the need to dispose of a large amount of ash and capture sulfur oxides SOx. It is shown that the joint combustion of carbonaceous residue and peat (25 wt. %) allowed reducing the amount of ash residue formed. In addition, when adding 25 wt. % of sukhovskoу peat it was possible to reduce the amount of generated SO2 emissions by more than 3 times. This effect is due to the gas phase interaction with peat mineral part, namely, with calcium and magnesium carbonates.

THE PURPOSE. To assess the possibility of burning coal sludge, waste of coal preparation, in the furnaces of power boilers at the thermal power station of the Irkutsk region. METHODS. Technological and mathematical research methods were used to analyze the incineration of coal preparation waste. RESULTS. The article presents the experience of using coal preparation wastes from Cheremkhovsky coal at CHPP-12 of Irkutskenergo. Presented are the results of thermal tests of the TP-30 boiler at CHPP-12 during the trial combustion of granular waste from coal enrichment together with waste from marble production mixed with Golovinsky coal. As a result, it was revealed that the main parameters of the boiler operation practically did not change, there was a slight decrease in the temperature of the air mixture at the outlet of the mills in comparison with pure Golovinsky coal, which is due to the higher moisture content of the resulting mixture, in addition, there is a decrease in sulfur dioxide emissions by 18- 30% in depending on the proportion of granular waste of coal preparation in the mixture. CONCLUSIONS. Experimental studies carried out at CHPP-12 when burning Golovinsky coal mixed with granular waste of coal preparation in amounts up to 30% of the total amount of the mixture indicate that granular waste of coal preparation can be burned without any special restrictions in the operation of the equipment of the CHPP. Based on the results obtained, an analysis was carried out and recommendations for the incineration of coal preparation wastes were developed.

Studies on the influence of applying various technologies for combustion knock reduction have been presented in the paper. Among others, investigation concerning the following: over-expanded cycle, variable valve timing, internal and exhaust gas recirculation, leaning the combustible mixture and cooling the in-cylinder charge were of the interest. The research works were focused on impact of these technologies on both knock intensity reduction, and engine performance and toxic emissions. Results presented in the paper were coming from experimental investigation based on in-cylinder combustion pressure data acquisition. Additionally, knock intensity calculation methods were discussed. They are based on incylinder combustion pressure pulsations. Combustion knock intensity expressed by the maximum peak of the incylinder pressure pulsations shows a strong negative correlation with both the EGR ratio and relative equivalence ratio – lambda. With respect to a catalytic converter installed on the exhaust pipe line, applying EGR appears as better solution for knock reduction then leaning the combustible mixture because the catalytic converter needs stoichiometric mixture for effective NOx reduction. Furthermore, application of the over-expanded cycle to the hydrogen or coke gas fueled IC engine significantly reduces intensity of potential knock by 50 % in comparison to Otto cycle for all loads. Additionally, over-expanded cycle contributes to increase in engine thermal efficiency. Summing up, all the presented measures and technologies can be successfully implemented into practice in stationary engines as well as in traction engines, both of them working on either natural gas or gaseous renewable fuels.

The analysis of the state of modern technologies for utilization of reinforced polymers is carried out. The task of the study was formulated. Based on thermodynamic analysis and consideration of various combinations of compositions for conducting experiments, six types of test multicomponent samples were selected for conducting experimental studies on their combustion. To determine the maximum combustion temperature, the ignition temperature of the samples, and the mass of combustion residues. The analysis of the results obtained was carried out, and the compositions of the components for further research were identified

The methane-hydrogen fraction is a gaseous hydrocarbon by-product during oil processing for obtaining petroleum products. Until recently, the methane-hydrogen fraction was used as furnace oil in internal technological processes at a refinery. Some of the low-calorie methane-hydrogen fraction was burned in flares. Driven by the prospect of the methane-hydrogen fraction use as a fuel alternative to natural gas for burning in thermal power plants boilers, it became necessary to study the methane-hydrogen fraction combustion processes in large volumes. The conversion of ON-1000/1 and ON-1000/2 furnaces from the combustion of the methane- hydrogen fraction with combustion heat of 25.45 MJ/m3 to the combustion of the composition with combustion heat of 18.8 MJ/m3 leads to a decrease in temperature in the flame core for 100 °C as an average. The intensity of flame radiation on the radiant tubes decreases. Therefore, the operation of furnaces during combustion of methane-hydrogen fraction with a low heat of combustion at the gas oil hydro-treating unit is carried out only with a fresh catalyst, which allows lower flame temperatures in the burner.The experiments to determine the concentration of nitrogen oxides NOx and the burning rate w of the methane-hydrogen fraction in the ON-1000/1 furnace and natural gas in the TGM-84A boiler, depending upon the heat of combustion Qnr were carried out. The obtained results showed that the increase in the hydrogen content Н2 from 10.05 % to 18.36% (by mass) results in an increase in the burning rate w by 45%. The burning rate of natural gas with methane CH4 content of 98.89% in the TGM-84A boiler is 0.84 m/s, i.e. it is 2.5 times lower than the burning rate of the methane- hydrogen fraction with H2 content of 10.05%. The distributions of heat flux from the flame qf over the burner height h in the TGM-84A boiler were obtained in case of natural gas burning and calculation of burning of the methane-hydrogen fraction with a hydrogen content of 10.05% and methane of 28.27%. The comparison of the obtained data shows that burning of methane- hydrogen fraction causes an increase in the incident heat flux qf at the outlet of the burner.

One-dimensional axis-symmetrical and plane-symmetrical problem of propagation of the combustion and displacement fronts in oil-containing layer in situ has been considered numerically. Two combustible components, viz. liquid (oil) and solid (kerogen, oil sorbate), were considered. The influence of the blast rate, liquid component viscosity, oxygen concentration in blasted air and heat losses (the width of the oil-containing layer) on the dynamics of the heat dissipation and displacement fronts is investigated. In the cylindrical system the oxidizer flow to the combustion front is reducing over time; and the shift-down of the maximum temperature from the solid combustion front to the oil displacement front takes place (the combustion front “jump”). The time of the “jump” may vary from tenths to hundreds of days and the distance of the shift, – up to 10 or more meters, depending on the parameters of the system. After the “jump”, the combustion rate and maximum temperature continue to deteriorate and after the period of time close to the time lapse before the “jump” the chemical reaction ceases. Herewith the transition of combustion to the liquid phase after the “jump” doesn’t influence notably on oils displacement front speed. The time of the “jump”, as well as the velocity of the mutual combustion (maximum temperature) front and displacement front removal nearly linearly depends on incoming gas blast rate and non-linearly – on oil viscosity. When viscosity is low, the displacement front rapidly runs away from the combustion front, time of the “jump” retards and the distance between the fronts at the instance of the “jump” may reach 10 m or more. The oxygen concentration in the gas being blasted influences significantly on the mutual dynamics of the combustion and displacement fronts since combustion front velocity is proportional to oxygen concentration and displacement front velocity is independent on it. Oxygen enrichment of the gas being blasted just after the “jump” may help localize the area of heat release (combustion) near the oil displacement front. The mentioned manipulation may be utilized for sustainability control of the displacement front. However for its practical implementation it is necessary to have information on concentration and temperature fields inside the layer, which may be obtained from indirect data and via modeling. The results of investigation may be utilized for development of technical projects of oil recovery via in-situ combustion.

The relevance of the research is caused by generation of a huge amount of oil refinery waste (mainly oil sludge and acid tars). The development of technologies for processing such type of raw materials is an important area for many research teams. Despite the significant harm to the environment, refining waste contains a huge energy potential. Therefore, it is necessary to create technologies that will combine both environmentally friendly recycling and effective use of this potential. Now, there are many different ways of such materials utilization. The main one is direct combustion. However, almost all existing approaches are expensive and difficult in their implementation. In addition, most of them do not provide the required environmental safety of the process. The main aim of the research is to demonstrate the applicability of the fluidized bed combustion method for efficient refinery waste utilization. Objects of the research are the oil/water mixtures of various component ratio modeling waste resulting from refining processes (production, storage, processing into commodity products). In addition, samples of real oil refining waste (oil sludge of various origin) were investigated. Methods: analysis of literary sources in order to determine the main approaches to oil waste utilization; physical experiments to determine ash, moisture and volatile content in the samples; physical experiment on combustion of model and real oil waste. Results. The paper analyzes the existing methods of thermal processing with a sufficiently detailed consideration of individual methods used in practice. In addition, a series of physical experiments on combustion of both model oil/water mixtures in various ratios and real oil sludges of various origin was carried out. The authors showed that the combustion of both model and real sludge under conditions of a fluidized bed of catalyst provides a high environmental safety of the process – the content of harmful emissions (CO, NOx, SO2) does not exceed 100 ppm. In addition, the studies have shown the possibility of implementing the autothermal mode of combustion, which allows one to use their energy potential in most efficient way.

Investigation of combustion of complex heterogeneous systems and particularly of twophase “combustible liquid – solid fuel” systems is topical because of the need to improve combustion of multicomponent and non-standard fuels as well as for resolution of specific ecological problems. The qualitative and quantitative peculiarities of combustion of two model combustible systems, notionally corresponding to the “sawdust – oil” and “wood chips – oil” mixtures are investigated numerically. The main peculiarity of the systems is volatility of the fluid component, being gaseous-flow driven inside porous media. A one-dimensional plain problem of combustion of compact layer with the ignition from the bottom and from the upper side is considered. It is demonstrated that due to low gas permeability of the fine-dispersed solid matrix (sawdust), air flow velocity is relatively low which results in slow formation of the combustion front (the characteristic time is tens of minutes). In case of coarse solid phase (wood chips), airflow rate is higher and corresponding time of temperature fronts formation is smaller (a few minutes). Both for the cases of fine-dispersed and coarse particles solid matrix phase, when set on fire from below, the fluid component is evacuated from the hot zone before the combustion front is formed. Since that, the main characteristics of the temperature front dynamics correspond to “dry” fuel system. In case of upper side ignition the combustion wave is formed at the time of the order of 100 s (when the used magnitudes of parameters are being used again), then it spreads downstream of the layer, accompanied by incomplete oxidation of solid fuel and complete combustion of oxygen. The effect of incomplete solid fuel combustion was noted earlier in the investigations of combustion of lean coal layer and some other systems. The velocity of the combustion wave propagation does not differ much for the cases of upper side and bottom side ignition. But the time of establishing the quasi-stationary velocity of the front to the steady-state value at the initial stage is much less in case of bottom side ignition. The results obtained by the authors can be utilized for optimization of multi-phase fuels combustion in compact layer, the regime parameters of in-situ combustion method of oil recovery increase as well as for improvement of some specific chemical processes.

In this paper, the criteria for determining the composition and physicochemical properties of aviation kerosene were formulated. The data on the physicochemical properties of known kerosene surrogates were systematized and classified. The main classes of individual chemical components of aviation kerosene were determined, and the main representatives of these classes which were used in the preparation of surrogates, were investigated. Four- and six-component kerosene substitutes are proposed. The physical properties of the developed surrogates were validated according to the flow characteristics and the spray angle of the flame of a centrifugal fuel nozzle. The dependence of the flame speed on the composition of the mixture of developed kerosene surrogates was determined. The results of determining the composition of combustion products during the combustion of TS-1 brand aviation kerosene and its surrogates in a model combustion chamber were compared.

Pulmonotoxicants are the substances causing structural and functional disorders of respiratory system. The main sources of pulmonotoxicants in the environment are thermal decomposition of synthetic polymeric materials in fires. The possibility of formation of pulmonotoxicants during the combustion of synthetic polymers of different composition with regard to the conditions of combustion (temperature, time, sufficient oxygen) was analyzed. The risk of lung damage has been considered taking into account the duration of exposure to the toxicant. In addition to general toxic carbon monoxide and cyanide, the products of thermal destruction of halogen-containing and nitrogen-containing substances pose a great danger in case of fire due to their high pulmonotoxicity. The lung damage risk is considered with account for toxicants exposure duration. The pulmonotoxicants classification has been proposed according to their hazard in relation to their concentration in the air. Main mechanisms of effect of pulmonotoxicants formed during the pyrolysis of various polymeric synthetic materials have been proposed. The description of clinical manifestations as the result of intoxication with these materials under various toxodoses effect has been shown. The hazardous risk spectrum has changed depending on the toxic exposure duration that determines the variance of treatment approaches: from possible etiotropic treatment to pathogenetic therapy of toxic pulmonary edema.

The one-dimensional axisymmetric problem of initiation of a combustion wave in an oil-saturated reservoir is solved numerically. Two combustible components, viz. liquid (oil) and solid (kerogen, oil sorbate) were considered. The influence of the abovementioned components on time of the hot site ignition and combustion front speed was simulated and analyzed. It was demonstrated that growth of the mass fraction of liquid component (the total heat content being preserved) results in retard of formation of the hot site near the well and in reduction of the maximum temperature of the combustion wave, disregarding of the higher reactivity of liquid combustible. Simulation revealed existence of the two “peaks” of thermal front velocity. The first one corresponds by time to ignition of combustion site. The second one corresponds to a moment when the solid component combustion front overrides the oil displacement front. Calculations shown, that thermal wave propagation velocity, at least after passing the “peaks” and transition to quasi-steady regime, does not considerably depend on mass traction of the fluid component in the system. A typical term of the exothermic reaction site formation may increase from 50 to 200 days in case of growth of the liquid component content from 30 to 80 mass % at the considered thermal conditions in the oil reservoir. Thus, the implementation of the thermo-gas method in high-productive layers increases the likelihood of difficulty of initiation of a fire. Therefore, the study of the regularities of intra-combustion in such cases is of a particular interest. For instance, the task of combustion site ignition may be resolved by increase of oxygen content in blowing-gas or by means of non-steady (periodical) blowing. It is found that taking into consideration of highly reactive liquid component results in widening (diffusion) of the thermal front, which may play positive role in its spatial thermo-hydrodynamic stabilization. The results of simulation may be utilized for development of technical projects of oil recovery via in-situ combustion, for designing of furnaces utilizing multicomponent fixed layer fuels and for thermochemical investigation of multicomponent fuels.

The relevance of the research is caused by the need to involve renewable biomass (in particular, peat) to generate heat and electrical energy. This will partially solve the problem of resource-deficient regions, depending on the supply of fuel from developed coal deposits. The main aim of the research is the investigation of thermal characteristics and the mineral matter of the peat of a number of large deposits of the Tomsk region to assess the possibility of their energy use. Objects of researches are the samples of low-moor peat from Sukhovskoye and Arkadyevskoye deposits and one of the Tomsk region deposits. Methods. Thermal characteristics of the studied samples were determined according to GOST 33503-2015 (ISO 11722:2013), 55661-2013 (ISO 1171:2010), 55660-2013 (ISO 562:2010). Net calorific values of the peats were determined in the ABK-1 calorimeter (Russia), the elemental composition of the organic matter was determined using the analyzer Vario Micro Cube (Elementar, Germany). Peat mineral matter composition was studied by X-ray fluorescence analysis using an EDX-720-P spectrometer (Shimadzu, Japan) as well as by X-ray diffractometry using a Shimadzu XRD7000 diffractometer (CuKα-radiation) with a Shimadzu CM-3121 monochromator counter. Typical ash melting points were determined according to GOST 2057-94 (ISO 540-81). The structure of the samples under study was examined by scanning electron microscopy using a TM 3000 electron microscope (Hitachi, Japan). Results. On the basis of the obtained results, it can be concluded that, due to the high ash content, the use of okolotomsky peat for chamber-type combustion is impractical. However, this resource can be considered as a mineral fertilizer in agriculture due to the presence of such elements as phosphorus, potassium. The high content of carbonates indicates the possibility of its using as an additive to high-sulfur coal to reduce emissions of sulfur oxide SOx. The characteristics of sukhovskoу and аrkadyevsky peat make it possible to consider them as an alternative to imported fuel. The preferred method of energy use of peat from Tomsk region fields is its combustion in a fluidized bed.

The difficulties of burning the watered fuel oil used at the TPP as a reserve fuel for boilers are associated with its preparation by heating to reduce viscosity and the choice of a method of spraying with nozzles into the combustion zone. The quality of the preparation of fuel oil for combustion affecting the boiler efficiency is estimated by the length of the flame, the presence of burning large particles of fuel oil, the injection of coke and unburned particles onto screen and other heat-receiving surfaces. One of the ways to prepare fuel oil for combustion is cavitation treatment, which results in an emulsion consisting of fine micronsized particles. Heating of fuel oil particles after the nozzle in contact with the combustion zone is due to the flow of radiation from the burning torch. Therefore, in this article, the values of the flux density from the torch during the combustion of fuel oil are experimentally determined. The influence of particle size on the burning rate of the fuel oil M100 with the different density of the thermal radiation of the flame. It is found that the effect of cavitation treatment of fuel oil on the combustion rate is most significantly manifested in particle sizes less than 10 microns. For this purpose, the use of hydrodynamic cavitators are preferred at high fuel oil consumption rate.

Ammonium bifluoride is a by-product of a number of industrial processes, which has not sufficient marketing in the industry. Thus, it should be created a method for producing hydrogen fluoride, the major fluorinating agent in the modern industry, from ammonium bifluoride. The authors propose a way for producing hydrogen fluoride by processing ammonium bifluoride in oxygen. Adiabatic temperature of the products is about 2400 K. In this paper, using the calculations performed via thermodynamic program complex ASTRA.4, it was shown that at a following ratio of chemical elements N-5H-2F-1,5O appropriating to the proposed process, in the equilibrium mixture in the temperature range 600-2500 K, hydrogen fluoride is the only fluorine-containing substance. Nitrogen fluorides and hydroxy nitrogen fluorides are absent. Combustion of ammonia in oxygen had been extensively studied. However, there is have not been uncovered any data about this process in literature. The authors have experimentally investigated the combustion process of ammonia and oxygen in the presence of hydrogen fluoride. It have been showed that, for the tunnel burner reactor type used in the experiments, at a molar ratio of ammonia to hydrogen fluoride flow rates 1:2, it is possible to form a stable flame in oxygen, supplied by stochiometry, only by utilizing methane as fuel. The conditions were determined for the ratio of the components consumption, when, in the combustion mode, the conversion of ammonia, when methane was fed into the reaction zone, reached 98 % in a laboratory installation, and hydrogen fluoride remained stable.

Uranium hexafluoride, depleted in the isotope U-235 (DUHF), is a by-product of the isotopic enrichment of uranium in the nuclear fuel cycle, which is sent for long-term storage. Currently, there are no effective industrial technologies allowing to return fluorine into the technological cycle. The authors of the article propose a method for processing DUHF in a flame of hydrogen-containing fuel (for example, hydrogen) and oxygen, on the basis of which hydrogen fluoride and uranium oxides can be obtained. Using the program code of our own design and the ASTRA.4 complex, thermodynamic calculations of the equilibrium compositions of substances in the UFHO system of elements were performed and it was shown that if the number of hydrogen atoms exceeds the number of fluorine atoms, then in a thermodynamically equilibrium mixture at a temperature above 1150 K, the main fluorine-containing substance is hydrogen fluoride, and the main uranium-containing one is uranium dioxide. The specified temperature can be achieved by processing DUHF in a hydrogen and oxygen flame. This process was experimentally investigated on a pilot plant created by the authors and it was shown that the composition of its products is close to thermodynamic equilibrium. The results obtained can become the basis for industrial technology for the production of anhydrous hydrogen fluoride from DUHF.

In the article there is considered one of directions of increase of efficiency of use of coal — burning coal-water fuel (CWF). There is developed a physical and mathematical models of the combustion of droplets of CWF with division of the process into a sequence of repetitive stages of evaporation and burning out of the solid phase. The formula for calculating the time of burnout of a single drop of CWF on the basis of the Sreznevsky equation is obtained. The results of calculation of time of burning of a drop depending on a radius of a drop and a moisture content are presented.

An original improvement of modern information models of conventional engine is proposed. Within the model all internal as well as external processes related to engine are integrated to a general system. Additional procedure to simulate nitric oxide kinetics in a combustion chamber is elaborated. The problem of exhaust toxicity is solved in relation to partial engine loads. Compared to prototypes the model enables to estimate engine toxicity appreciably more precise.

Some original modifications of the genetic algorithms for analyzing the stationary states of the chemical dynamic systems at the defined thermodynamic parameters, IC engines among others, are offered. The development feature is allocation of small and large equation parameters among the equations and their solutions. Along with the known neuronet methods, the development can be integrated in ‘Engine’ simulation system.

The problem of the combustion of a gas suspension with an inhomogeneous distribution of particles over space occurs exists for the coal dust suspension combustion in combustion chambers and burners. The inhomogeneous distribution of particles in space can significantly affect the combustion velocity of the aerosolve of coal dust. The purpose of the present work is the numerically study the effect of the inhomogeneous distribution of particles and the composition of the coal dust on the combustion velocity of the coal dust in the air. The physical and mathematical model of combustion of air-coal dust mixture with an inhomogeneous distribution of coal dust particles over space has been developed. The physical and mathematical formulation of the problem took into account the release of combustible volatile components from the particles upon their heating, the subsequent reaction of volatile components with air, a heterogeneous reaction on the surface of the particles, and the dependence of the thermal conductivity of the gas on temperature. A parametric study was made of the effect of mass concentration, the content of volatile and the particle size of coal dust on the burning speed of a suspension of coal dust in the air. It is shown that the burning rate is greater for particles with a lower content of volatile components. The influence of the spatial distribution of particles on the burning rate of the coal-air mixture is analyzed. It is shown that the propagation velocity of the combustion front with respect to the suspension with an inhomogeneous particle distribution is higher than the propagation speed of the combustion front with respect to the suspension with a homogeneous particle distribution.

The paper presents results of the study of processes of coal dust detonation combustion obtained using a technique approved by the authors. The essence of the technique is the use of a specific coal dust fraction to study the explosion pressure, explosion pressure increase rate and transformation coefficient. It allows applying the results of a laboratory experiment to the actual data of explosion and combustion of dust and gas mixtures of mines that have a much larger volume. In other words it allows predicting the explosion pressure increase rate in relation to specific excavation of coal mines. The methodology for studying combustion and detonation processes, briefly described in the article, is based both on requirements of modern regulatory documents and the practical experience of research institutes engaged in similar research. The practical component of the method is based on an installation which represents an explosive combustion chamber in the form of a sphere with a volume of 20 liters. The data of detonation combustion are processed using application software and presented graphically in three figures. It is shown that dispersion composition of coal dust indluences on the explosion pressure, explosion pressure increase rate and transformation coefficient. Research work is carried out with a sample of coal of KS-type from a thick beam of the mine named after Dzerzhinskiy. As a result of the analysis of digital and graphic data obtained during processing, it is proved that dust with fractional composition of 63-94 μm is the most explosive. It is revealed that explosion pressure increase rate changes as a function of dust concentration in the installation reaction volume in the way that there was two maxima of the explosion pressure increase rate where one was at 100 g/m3 and the second at 400 g/m3. The results obtained during determination of the explosion pressure increase rate have shown the necessity of a non-trivial, more thoroughtful approach to study explosion pressure increase and, consequently, determin the transformation coefficient. In addition, analysis of the experimental data presented in the article confirmed that during the development of means of flame retardation and explosion suppression used in automatic means for explosion localization it is necessary to carry out further investigations with the coal dust fraction equal to 63-94 μm. The results obtained in the work will allow starting the study of the processes of detonation combustion in a dusty air containing methane.

А calculation scheme for the utilization of chips of old wooden sleepers in a vortex furnace is proposed. The vortex furnace provides two zones of reaction of a combustible substance with air: the primary zone is the gasification of old sleepers and the afterburning of the solid residue with a lack of air oxygen, the secondary zone is the burning of the gas phase. The initial data for the thermodynamic calculation is given. The results of the equilibrium calculation of the thermal decomposition of wood on the grate and the combustion of gasification products are presented for different values of the excess air factor, as well as some experimental data. A comparison of the calculation results with the experimental data is carried out.

The article presents the estimated environmental performance of the boiler KV-GM-100 (116,3/150) burning high-sulphur oil received on the basis of modeling of characteristics of the combustion process. The analysis of the influence of the residence time of combustion products in the furnace, the average integral temperature in the zone of active combustion, the adiabatic combustion temperature of the fuel on the intensity of the formation of nitrogen oxides and benzpyrene in flue gases. The resulting new mathematical dependences for calculation of the concentrations of toxic components of flue gases based on temperature and time parameters of the combustion process and combustion products of fuel oil.

Copyright of Stratum Plus Journal is the property of P.P. Stratum plus and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Cybernetics & Systems Analysis / Kibernetiki i Sistemnyj Analiz is the property of V.M. Glushkov Institute of Cybernetics of NAS of Ukraine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Showing comparative thermal and aerodynamic characteristics of technological tubular furnaces with injection burners located on the roof of the chamber and the acoustic radiation burner flame grazing arranged in one layer on the side wall. Isotherm shown in the amount of radiation chamber, view lines of the stream function, the distribution of molar concentrations of radiating components of the combustion products and graphs of the surface heat flux density along the length of the reaction tubes. The results obtained by numerically solving the system of equations of two-dimensional radiative transfer in S2 - approximation of the discrete ordinate method, the energy of the turbulent motion of the combustion products, k - e turbulence model and a simple model of the combustion of gaseous fuels.

As part of the differential method for calculating complex heat transfer in furnaces held a three-dimensional calculation of temperature and velocity fields of gaseous combustion products when using acoustic burner flame grazing type AGG. The method is based on the joint numerical solution of finite difference analogue of three-dimensional equations of radiation transport, energy, turbulent flow of flue gas and methane combustion model in the air. To account for the selectivity of heat radiation region is divided into six strips. A diagram showing the organization of a three-dimensional simulation of the burner. Results isotherm flatness of the wall around the burner and combustion products in the various sections of the furnace, and also shows the direction of movement of the combustion products.

Organization of pulsating combustion mode is one of the possible solutions to improve energy efficiency installations tasks that use hydrocarbon fuels. For stratified combustion of solid fuels, especially solid waste technogenic promising are coaxial system, allowing to provide secondary air flow to the combustion zone. In this paper, an analysis of its own oscillations of gas in coaxial pipes system. The effect of the mutual arrangement of the combustion chamber and the resonance frequency of the pipe on the gas fluctuations.

This article deals with the distribution of temperature and incident heat flux on the display surface boiler heating TG-104 at work at the Urengoy gas and the thermal efficiency of the burners to reduce the formation of nitrogen oxides. The temperature of the combustion products was measured using an optical method and thermocouple contact method. The incident heat fluxes measured by the radiometer the full radiation. Burned fuel - natural gas according to GOST 30319.1-96 with the lower heat of combustion 35146 kJ/m3.

We consider the possibilities of combustion and detonation initiation for propane mixtured with air by microwave discharges created by a quasi-optical electromagnetic beam. Comparison of initiation is performed by different types of discharge: spark, streamer, and attached one. The formation theory of streamer discharges is given, the velocity of their propagation and the volume of energy supplies are analyzed. Experiments have been carried out together with calculation of the propane-air mixture ignition by various types of discharges. It is shown that when burning is initiated by a streamer discharge, a multiple increase in the propagation velocity of the flame front and the completeness of the fuel combustion is obtained as compared to a spark discharge with an equal energy contribution. In the prechamber initiation of combustion by igniting a streamer discharge on the inner walls of the quartz tube, a significant acceleration of combustion was obtained up to the rates characteristic for the transition of deflagration to detonation. The results can be applied in the development of multivolumetric volumetric ignition systems in internal combustion engines, gas turbine engines, low-emission combustion chambers, for combustion in supersonic flow, and in combustion chambers for detonation engines.

We consider a nonstationary process of spreading some substance in a one-dimensional spatially inhomogeneous system of cells. It is assumed that a change in the concentration of \(u_n (t)\) in a cell with the number \(n\) with time \(t\) is determined by the difference in concentration in this cell and in its two neighbors on the left and on the right, as well as the source density, which depends on \(n\) and depends on \(u_n (t)\). Such a model leads to the initial-boundary value problem for the differentialdifference equation (differentiation with respect to t variable, the difference expression with respect to \(n\)). With a sufficiently small difference in concentration in each pair of neighboring cells we can replace the difference expression by the second partial derivative with respect to the spatial coordinate, and describe the propagation by the reaction-diffusion equation. This equation belongs to the class of quasilinear parabolic equations. It is assumed that the density of the sources vanishes (with changing the sign) at three values of the concentration, two of which, lower and upper, are stable. There is also an intermediate unstable state with zero source density, in which the sign reversal also takes place. The peculiarity of our model is that we assume, that two extreme roots of the source density function are degenerate (with an integer or fractional exponent). We intend to show analytically and by the computer simulation, that this model leads to the fact, that the rate of asymptotic aspiration of concentration to equilibrium values for a moving front becomes power-law instead of exponential, which takes place for standard models. In the paper, we have constructed a formal asymptotics solution of the initialboundary value problem for the reaction-diffusion equation in a homogeneous medium with a power-law dependence of the source density on the temperature, an upper and lower solutions are constructed, a rigorous justification of the formal asymptotics is given. Precise solutions of the diffusion reaction equation are constructed for a wide class of source density functions.

The article describes methods of investigation of the processes inside the combustion chamber of the gas turbine engine. The investigation is aimed at revealing changes in the combustion chamber workflow depending on the changes in the operating conditions of the gas turbine engine. Such investigations allow us to find design flaws and analyze possibilities of removing them. The main advantage of these investigations is that all experiments have been conducted in full scale. The article also presents a principal scheme of the test facility on which an engine was tested. The parameters being measured and methods of conducting measurements in the combustion chamber are presented. The conclusion is made that the implementation of measures described in the article makes it possible to analyze the intrachamber processes with the aim of developing it or testing various methods of providing its durability.

Some relations between various auto- and soliton models are investigated. Common features in the problem formulation of combustion, supersonic radiation wave propagation and moving of soliton wave on soundings are revealed. Realization of the known mathematical solutions for wave flame structure characterization in the reciprocating motor grain is proved.

Copyright of Renewable Energy / Vidnovluvana Energetyka is the property of Institute of Renewable Energy of NAS of Ukraine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The physical and mathematical model of combustion of the polydisperse suspension of coal dust was developed. The formulation of the problem takes into account the evaporation of particle volatile components during the heating, the particle emitting and the gas heat transfer to a surrounding area via the sphere volume side surface, heat transfer coefficient as a function of temperature. The polydisperse of coal-dust is taken into consideration. N - the number of fraction. Fractions are subdivided into inert and reacting particles. The oxidizer mass balance equation takes into consideration the oxidizer consumption per each reaction (heterogeneous on the particle surface and homogenous in the gas). Exothermic chemical reactions in gas are determined by Arrhenius equation with second-order kinetics. The heterogeneous reaction on the particle surface was first-order reaction. The numerical simulation was solved by Runge-Kutta-Merson method. Reliability of the calculations was verified by solving the partial problems. During the numerical calculation the percentage composition of inert and reacting particles in coal-dust and their total mass were changed for each simulation. We have determined the influence of the percentage composition of inert and reacting particles on burning characteristics of polydisperse coal-dust methane-air mixture. The results showed that the percent increase of volatile components in the mixture lead to the increase of total pressure in the volume. The value of total pressure decreases with the increasing of the inert components in the mixture. It has been determined that there is the extremism radius value of coarse particles by which the maximum pressure reaches the highest value.