bluuebunny/crossref_metadata_2025 huggingface dataset:
IMPROVING THE PLANTS EFFICIENCY OF THERMAL INCINERATION HOUSEHOLD WASTE BY RECOVERING WASTE HEAT
Authors: Fialko N.M. , Navrodska R. , Shevchuk S. , Gnedash G.
Published: February 2025

The work is devoted to research on the creation of recovery exchanger for waste heat exhaust gases of household waste incineration plants. The purpose of the work is to develop a technical solution for the heat recovery exchanger of waste incineration plants (WIP) and determine its thermal efficiency indicators. The main objectives of the study were to analysis of the modern experience of using the WIP and establish requirements for the creation of the exhaust gas heat recovery exchanger, develop a new technical solution for the heat recovery exchanger, and determine the change patterns in its main thermal indicators in different operating modes of the WIP. The known methods of thermal calculation of heat exchangers and the results of previous studies on the development and implementation of heat recovery equipment operating on dusty gases were used. The results of work on the creation of a new technical solution for an air-heating heat recovery exchanger with the ability to clean working surfaces from dust deposits are presented. The heat exchange surface of the heat recovery exchanger is composed of steel panels formed by tubes with membranes. The tubes applied have circular flow turbulizators on their internal surfaces. Turbulizators provide heat transfer intensification by 1.4 to 1.8 times with a moderate increase in aerodynamic resistance compared to other methods of heat transfer intensification. The regularities of changes in the main indicators of the heat recovery unit in different operating modes during the year in the practical range of changes in its input parameters were established. The research results show that, depending on the initial temperatures of gases and air, the excess air ratio in exhaust gases and the dust level of the working surface, the heat recovery exchanger provides heating capacity of 72-263 kW; cooling of exhaust gases to a temperature of 107-245 °C; heating of air to 96-220 °C. It was also established that the deposition of dust on the heat exchange surface of the heat recovery unit under the considered conditions leads to a decrease in the heating air temperature by 1.3-1.4 times and an increase in the final exhaust gas temperature by 1.1-1.2 times. At the same time, the heating capacity of the heat recovery exchanger is reduced by half. To increase heat recovery efficiency, it is necessary to periodically clean the working surfaces of the heat recovery unit with compressed air.
REFINED PHYSICAL MODEL OF STEAM FLOW IN THE LOW-PRESSURE PART OF A HIGH-POWER TURBINE IN LOW-FLOW RATE MODES
Authors: Shubenko O. L , Goloschapov V. M. , Kotulska O. V. , Paramonova T. M.
Published: February 2025

Analytical methods for calculating the performance of the turbine are operational as long as the “layered” character of the steam flow is preserved in the flow part. However, as shown by experimental studies, the character of the flow changes significantly in low-flow rate modes. In these cases, existing methods of three-dimensional calculations require reliable formation of boundary conditions. The purpose of this study is to analyze the characteristics of low-pressure cylinder (LPC) stages operating in high-power stationary steam turbines, and to form physical models of the flow of the working medium (steam) in such stages at low-flow rate modes, taking into account their location in the flow part. It is advisable to imagine the physical model of the movement of steam in the turbine, starting from the last stage of the LPC and the outlet nozzle, in which separation of flow from the hub the develops. Its formation occurs when the relative volumetric flow rate decreases, starting with = 0.8, depending on the angle b2к at the root of the working blades. A decrease in the operating mode of the LPC turbine stages is also accompanied by a decrease the flow speed in the peripheral zone and a negative angle of attack at the flow entry into the channels of the impeller. On the concave surface of the profile part of the blade, a separation area is formed, which rotates in the rim clearance in the circumferential direction. Reverse flow from the inlet part of the channels of the impeller into the rim clearance occur when the static pressure in it exceeds the full pressure of the flow coming out of the channels of the guide apparatus. Turbulization of the flow of the rotating vortex leads to large irreversible losses of the mechanical energy of the moving flow, which are converted into heat, heating the mass of the working medium of the vortex and the main flow averaged through the channels of the working blade. Thus, the analysis of the gas-dynamic structure of the flow and its thermal state made it possible to clarify the physical model of the steam flow in the LPC at low-flow rate modes.
INFLUENCE OF HEAT GENERATION ON DETONATION IN REAL GAS
Authors: Avramenko A.A. , Kovetskaya M.M. , Kondratieva E.A. , Skitsko O.I.
Published: February 2025

The study of detonation processes in gaseous media is of interest for the coal mining, aviation, aerospace industries, and hydrogen energy. Under high pressure conditions during the passage of a detonation wave, it is necessary to take into account the equation of state of a real gas, the effects of endothermicity and exothermicity.
The paper considers the flow of real gas through a plane detonation wave. A modified Rankine-Hugoniot equation has been obtained to describe the dynamics of changes in the parameters of a van der Waals gas flow when it passes through a detonation wave.
An equation for the maximum increase in gas density during the passage of a detonation wave is obtained. The influence of parameters A and B in the van der Waals gas equation of state on the asymptote of the maximum increase in density is shown. It follows from the equation that the asymptote of the maximum increase in density shifts to the region of lower values ​​of  r2/r1  with an increase in the value of parameter B, and parameter A does not affect the position of the asymptote of the maximum increase in density.
The influence of heat release and thermodynamic properties of gas on the pressure jump in the detonation wave is shown. Pressure jumps in a van der Waals gas are greater than in the case of an ideal gas. Calculations have shown that an increase in parameter A slows down the increase in pressure in the detonation wave, and an increase in parameter B enhances it. An increase in heat release leads to an increase in the pressure jump, to an equidistant increase in the Hugoniot curve compared to the case without heat release.
INVESTIGATION OF THE EFFECT OF DPEI-TREATMENT AND BIOPOLYMER ADDITIVES ON THE CHARACTERISTICS OF FRUIT HETEROGENEOUS SYSTEMS AS OBJECTS OF SPRAY DRYING
Authors: Turchina T. Ya , Avdieieva L.Yu. , Makarenko A.A. , Kozak M.M.
Published: February 2025

This research focuses on the crucial stage of raw material preparation in spray drying technologies, as it defines the potential properties of liquid heterogeneous systems and the characteristics of the resulting powder. The objective of this study was to examine the influence of DPEI treatment on different types of fruit and vegetable raw materials in two types of rotor-pulsation apparatus, along with the introduction of biopolymer additives, on the characteristics of obtained heterogeneous systems destined for spray drying. The article presents the results of investigating the effects of two types of rotor-pulsation apparatus, as well as the physico-chemical and morphological peculiarities of fruit and vegetable raw materials, on the dispersion process to obtain water suspensions with specified dispersion and structural-mechanical properties. Challenges encountered during the drying process of plant-based raw materials are highlighted, and the characteristics of the obtained suspensions (temperature, pH, degree of dispersion, flowability) after hydro-mechanical processing of heterogeneous systems are presented. The necessity of using biopolymer additives is justified. Three types of fruit and vegetable compositions were utilized in the research: berry, fruit-vegetable, and vegetable. To enhance thermal stability and improve structural, moisture-conductive, and structural-mechanical properties of the heterogeneous systems, as well as to create optimal conditions for subsequent spray drying, biopolymer additives such as starch syrup and whey protein concentrate were employed.
Based on the experimental and analytical investigations, it was determined that the introduction of structuring biopolymer additives during the first 2 minutes of hydro-mechanical treatment of fruit and vegetable masses improved their flowability and thermal stability during subsequent drying. This approach also resulted in pH stabilization at a level of ≥4.0, preservation of newly formed nano- and micro-particles of insoluble fractions and other thermolabile substances of the raw material in the dispersed medium of the heterogeneous system until it was fed into the spray dryer.
ENERGY AND ENVIRONMENTAL EFFICIENCY OF EVAPORATION AND DRYING OF LIQUID PRODUCTS IN A SINGLE EVAPORATION-DRYING UNIT
Authors: Shmorgun V.V. , Martiuk O.V.
Published: February 2025

The energy consumption indicators of the technology of combining evaporation and drying of liquid products in a single unit were studied. The results of the approbation of this technology are presented on the example of the operation in industrial conditions of the "ИСАР-700" unit, developed at the Institute of Technical Thermophysics of the National Academy of Sciences of Ukraine. Analysis of thermo-technological processing characteristics as applied to producing dry powdered milk products with using the evaporation-type recirculation drier "ИСАР-700" has been performed. It has been shown that the given technology, which allows the performance of both evaporation and drying processes with the aid of the same spray drier, may be considered as a very efficient method of dehydration from viewpoints of energy saving and environmental protection.
Thus, in the production of dry substitute for whole milk, 703 kWh were consumed for the evaporation process of 700 kg of moisture per hour by the "ИСАР-700" evaporation-drying unit. Electrical and thermal energy, i.e. 1.1 kWh of energy per 1 kg of evaporated moisture. These indicators testify to the high thermal efficiency of both the heat generators included in the "ИСАР-700" unit, as well as the practical implementation of evaporation and drying processes during the dehydration of dairy products by the spray method. Taking into account the significantly smaller (practically absent) emissions of powder into the environment, compared to the traditional technology of evaporation of dairy products in vacuum evaporators and drying of the concentrate in spray dryers, the absence of the need for steam, and therefore also in the boiler room, the absence of the need for large volumes of water for the operation of vacuum-evaporating devices, the absence of discharges into the sewage network of used water contaminated with dairy products, the technology of carrying out the processes of evaporation and drying of dairy products by the spray method in a single unit with its own autonomous heat generators can be considered as very effective, both from the point of view of energy consumption, and environmental cleanliness.
ENERGY EFFICIENT TECHNOLOGY OF RECTIFIED ETHYL ALCOHOL
Authors: Bulii Y.V. , Obodovych O.M. , Stepanova O.E.
Published: February 2025

In the conditions of rising energy prices, the urgent task for the alcohol industry is the development and implementation of energy-efficient technologies of rectified ethyl alcohol, which allow reducing water and steam consumption and increasing the output of the finished product from a unit of raw materials. To solve it, modernized distillation units (BRU) are being implemented, which work under rarefaction or provide for the heating of some columns by the secondary steam of high potential of other columns operating under pressure, equipping the units with booster and sieving columns, increasing the number of contact devices, using the heat of bard and Luther water , closed column heating, introducing cyclical installations, etc. A promising direction in the creation of energy-efficient technologies is the optimization of the operation of the heat exchange equipment included in the BRU, as well as the use of the heat of secondary steam.
One of the factors for optimizing heat exchange equipment is the correspondence of the heat transfer surface of dephlegmators and condensers to their heat load, as well as the methods of their connection to water communication. Also, to optimize the operation of heat exchange equipment, the connection schemes of dephlegmators and vertical condensers of BRU are of great importance.
The efficiency of the innovative technology of rectified alcohol has been determined under production conditions, which provides for the supply of alcohol-containing fractions in the form of non-condensed in the deflegmators of the main columns of vapour to the feed plate of the impurity concentration column. This solution allows to reduce the total water consumption by 0,032 m3/dal (5,1 %) and the heating vapour by 1,2 kg/dal (1,9 %) in terms of anhydrous alcohol in comparison with the known method. The expected profit for the plant with a capacity of 3000 dal of alcohol per day will be about UAH 1,5 million per year. Increasing the amount of non-condensed vapour from 2 to 5 % to feed the column will reduce the heating vapour consumption from 10 to 8,8 kg/dal, and increase the profit by 33,3 %. During the tests the qualitative indicators of rectified alcohol corresponded to the normative ones for "Lux" grade.
ANALYSIS OF DIRECTIONS TO OPTIMIZE LOGISTICS OF BIOMASS FUEL SUPPLY TO ENERGY FACILITIES
Authors: Zheliezna T.A. , Drahniev S.V.
Published: February 2025

The objective of the work is analysis of the best options for harvesting and logistics of biomass supply to energy facilities. Another purpose is to develop recommendations for implementing best practices of biomass logistics in Ukraine. Effective logistics of biomass fuel supply is one of the important prerequisites for a successful implementation of bioenergy projects. The share of logistics cost in the whole supply chain is 30...50% for biomass delivered to the consumer. In case of long-distance international transportation this share may reach more than 75%. The composition and complexity of harvesting and logistics operations, which affects the final product cost, depends on biomass source, type and commercial form (pellets, briquettes, chips, bales). The more compressed biomass is, the more efficient its transportation is from an economic and energy point of view in terms of ton-kilometer. Effective biomass supply logistics minimizes its cost as a fuel for an energy facility. This is important because fuel cost is the largest component (up to 70% and more) and often plays the crucial role in forming the price of energy produced. It is important for Ukraine to study and implement the best European experience in harvesting and logistics operations for biomass supply for energy conversion. In particular, this includes the creation of a system for biomass electronic trading as well as practical implementation of the concept for wood chips production from felling residues on a forest roadside. Drafts of required basic documents, including legislative ones, have already been developed for these areas. Other priority tasks for the domestic bioenergy sector are the mastering of technologies for corn and sunflower stalks harvesting, development of energy crops growing, creation of trade and logistics centers for wood/agrarian biomass or the implementation of other similar concepts, introduction of long-term contracts for biomass supply and payment for biomass delivered per its energy unit (not per ton), development of companies that specialize in biomass and biofuel logistics.
IMPROVING THE EFFICIENCY OF COMPLEX HEAT RECOVERY SYSTEMS OF BOILER PLANTS
Authors: Fialko N.М. , Navrodska R.O. , Shevchuk S.I. , Presich G.O.
Published: February 2025

The results of studies for heating boiler plants of the main thermal characteristics of complex heat recovery systems with deep cooling of flue gases of higher thermal efficiency are presented. Systems for heating various heat-transfer agents, which, in accordance with the needs of heating boiler houses, can be return heat-network water, cold water entering the chemical water-purification system (CWP), and combustion air are considered. Two effective variants of such complex systems have been developed. These options differ in the sequence of installation of heat recovery exchangers for heating combustion air and cold water for the chemical water-purification. In the first variant, the heat-recovery exchanger for heating air is placed after the heat-recovery exchanger for heating the heat-network water in front of the heat exchanger for heating water for the CWP, and in the second, on the contrary, after the latter. In order to protect the gas exhaust ducts from condensate formation, these systems provide for the joint application of two thermal methods: air and drying in the gas-heater. The thermal efficiency of the developed system options was investigated according to such indicators as efficiency and coefficient the use heat of fuel of boiler CUHF, heating capacity and condensate formed volume of the system in different modes of boiler operation during the heating period. Studies have shown that these systems provide a 6.8-8.3% increase in coefficient the use heat of fuel of boiler CUHF. At the same time, the total indicators of the considered heat recovery systems are approximately the same for the two options. The redistribution of the values of these indicators is carried out in separate heat-recovery exchangers. On the basis of the conducted studies, the choice of the most rational option of the complex heat recovery system with the placement of heat recovery exchangers according to the second of the considered options is substantiated. This technical solution allows the aggregation of two water-heating exchangers in one housing. This aggregation provides increased compactness of the heat-recovery equipment and reduction of heat losses from the surface of the connecting gas ducts and pipelines.
THE STUDY OF THE INFLUENCE OF HYDRODYNAMIC CAVITATION EFFECTS ON THE PROPERTIES OF COMPLEX MULTICOMPONENT SYSTEMS
Authors: Avdieieva L.Yu. , Pavlyk V.Yu.
Published: February 2025

Emulsions have high efficiency and biological activity, easy absorption, and high digestibility, because they include extracts and parts of medicinal plants, essential oils, vitamin and mineral complexes. They are widely used in medicine, pharmaceutical, chemical and food industries, as well as agriculture. At the same time, the treatment of liquid multicomponent heterogeneous systems to obtain stable micro- and nano emulsions is a long and energy-intensive process.
Modification or replacement of obsolete energy-intensive technological processes and equipment to increase their efficiency is one of the main problems of modern production.
Various cavitation devices have proven to be highly efficient and productive with low energy consumption when producing high-quality liquid emulsion systems.
Streaming hydrodynamic cavitation devices of the static type based on the Venturi tube are reliable high-performance equipment and are widely used for the formation of microemulsions by hydrodynamic cavitation. Although the influence of Venturi tube geometry on the occurrence of hydrodynamic cavitation has been widely studied, there is no clear relationship between cavitation and Venturi tube geometry parameters.
The aim of this work was to study the influence of the geometry features of the Venturi nozzle design in cavitation mixers on the flow characteristics in the formation of emulsion systems as the basis of light emulsion creams.
The presented results of experimental studies describe the influence of the geometry features of the Venturi nozzle design on the flow characteristics during the formation of emulsion systems in static cavitation mixers. Flow rate, flow velocity, Reynolds number and cavitation number are defined among the characteristics of hydrodynamics of the flow. The quality of the obtained emulsions is evaluated by dispersion and stability of the emulsion over time.
ANALYSIS OF ACTIONS FOR UKRAINE TO COMPLETELY REJECT RUSSIAN NATURAL GAS
Authors: Geletukha G.G. , Zheliezna T.A. , Drahniev S.V. , Haidai O.I.
Published: February 2025

The aim of the work is to identify and analyse the most effective measures for Ukraine to completely reject Russian natural gas. The annual consumption of natural gas in Ukraine is about 28 billion m3, while the volume of its own production makes up around 20 billion m3/year. In recent years, Russian gas has been imported from Slovakia, Hungary and Poland. To achieve Ukraine's independence of Russian natural gas, it is proposed to implement ten actions: replacement of natural gas with biomass and solid biofuels for heat production; further construction of wind and solar power plants; production of biomethane; increasing the flexibility and level of decarbonization of Ukraine’s energy system; improving energy efficiency in district heating systems, buildings and industry; substitution of Russian supplies with natural gas from other sources; introduction of heat pumps; extension of the service life of existing nuclear power plants; encouraging consumers to temporarily reduce the room temperature by 1°C; introduction of natural gas storage obligations. The implementation of the suggested actions may provide projected reductions in the consumption or replacement of natural gas in the amount of 10 billion m3/year by 2030 and 25.8 billion m3/year by 2050. Among these actions, switching to biomass and solid biofuels for heat production could replace 3 billion m3/year by 2030 and 10.3 billion m3/year by 2050. The production and consumption of biomethane might substitute 0.8 and 3.7 billion m3/year of gas in 2030 and 2050, respectively. A number of required organizational and legislative measures have been formulated to implement the proposed actions to replace Russian natural gas in Ukraine. When the military operations end, Ukraine will urgently need to elaborate an effective and ambitious program to reject Russian gas, coal, oil and oil products within several years.
EXPERIENCE OF EU COUNTRIES IN DEVELOPING RENEWABLE ENERGY AND REDUCING NATURAL GAS CONSUMPTION
Authors: Geletukha G.G. , Zheliezna T.A. , Drahniev S.V. , Haidai O.I.
Published: February 2025

The aim of the work is to analyse the experience of EU countries in reducing the consumption of natural gas and other fossil fuels, the development of renewable energy sources and improving energy efficiency in order to determine the most effective measures for their implementation in Ukraine. In the last months before the start of Russia's war against Ukraine, there was a significant increase and fluctuations in natural gas prices in Europe. After a period of some stabilization, there was a sharp surge in prices with a peak of up to 2300 EUR/1000 m3 in the first half of March 2022 (TTF gas hub data). By mid-April 2022, the gas price dropped to 1000…1100 EUR/1000 m3, however there is no objective reason for its further reduction. The urgent task for the European Union and for Ukraine is to completely reject Russian natural gas. It is likely that even after switching to other potential suppliers (such as Qatar or the United States for exporting liquefied natural gas), the prices will not fall due to reduced supply of Russian gas in the market and increased competition for this energy source. Among the priority measures to replace Russian natural gas, most experts name the large-scale development of renewable energy sources and the implementation of energy efficiency measures. It is important to note that biomethane and all types of solid biomass are becoming fully competitive with natural gas at the current prices from an economic point of view. For many years, the European Union has been pursuing a comprehensive and consistent policy of reducing fossil fuel consumption, developing renewable energy and improving energy efficiency. Currently, the EU countries are making significant efforts to ensure the overall decarbonisation of the economy, a significant part of which is the decarbonisation of energy. Perspective areas include the introduction of production and consumption of biomethane, renewable hydrogen, and second-generation biofuels, as well as electrification of transport and industry.
PROSPECT FOR THE USE OF SECOND GENERATION BIOFUELS AS JET FUEL
Authors: Zheliezna T.A. , Drahniev S.V. , Bashtovyi A.I.
Published: February 2025

The aim of the work is to analyze the prospects for the development of bioenergy sector related to the production of second-generation aviation biofuels in the world and in Ukraine. The transport sector is a powerful source of greenhouse gas emissions. To meet the ambitious goal of achieving climate neutrality by 2050, the EU must reduce greenhouse gas emissions by 55% by 2030 from 1990 levels. According to experts, up to a third of this reduction is accounted for transport. Compared to other sectors, transport is difficult to decarbonize; this is especially true in segments such as aviation and water transport where electrification opportunities are limited. Therefore, in these segments it is necessary to move, first of all, to the use of second generation liquid biofuels. Today, the only technology for alternative aviation fuels that has fully reached the commercial level is the production of hydro-treated esters and fatty acids (HEFA). The reason for the possibility of commercialization was the development of technology for obtaining renewable diesel – hydro-treated vegetable oil (HVO). Each HVO plant can separate 15-50% of the fraction of hydro-treated esters and fatty acids, from which it is possible to obtain such aviation biofuel as synthetic paraffin kerosene (HEFA-SPK). The results of the preliminary feasibility study for the production of HEFA from false flax oil in Ukraine show that under the current conditions, such a project is not profitable given the high cost of this oil. To ensure profitable production and sale of HEFA aviation biofuel on Ukraine’s domestic market, it is necessary to work towards reducing the capital and operating costs of the project and/or introduce a temporary state subsidy for the production of sustainable liquid biofuels.
OPPORTUNITIES FOR REDUCTION AND REPLACEMENT OF NATURAL GAS CONSUMPTION IN DISTRICT HEATING OF UKRAINE
Authors: Geletukha G.G. , Zheliezna T.A. , Drahniev S.V.
Published: February 2025

The aim of the work is to identify and analyze the necessary steps for Ukraine to reject Russian natural gas. Russia's war against Ukraine has challenged our country, the EU and the world to an urgent introduction of embargo on the purchase of oil, gas and coal from the aggressor country. Unfortunately, Ukraine has to buy about 40% of its energy abroad, including from Russia, the required import of natural gas in recent years being 8… 10 billion m3/year. With the projected development plans and implementation of the proposed measures, by 2030, Ukraine will be able to completely reduce/replace the imported natural gas in the amount of up to 10 billion m3/year and become independent of it. By 2050, the volume of the reduction/replacement of natural gas may reach almost 26 billion m3/year. Substitution of natural gas with biomass and solid biofuels in heat production is one of the most cost-effective ways, especially given the current and projected high prices of natural gas in the EU, where Ukraine is currently purchasing it. In addition, Ukraine can potentially produce up to 10 billion m3 of biomethane/year, mainly from agricultural waste and residues such as manure, cereal straw, corn stalks, sunflower stalks, sugar beet pulp, molasses, corn silage, as well as municipal waste and other types of biomass. By 2050, the total production of biogas/biomethane in the country may reach 6 billion m3/year, some of which can be exported. We believe that Ukraine as soon as possible needs to develop an effective and ambitious state program to reduce and replace the consumption of imported gas, which should be the basis for the recovery of Ukraine's energy sector.
IMPROVEMENT OF THE CONDITIONS OF DISPERSAL OF HARMFUL EMISSIONS FROM GLASS FURNACES IN CASE USING HEAT-RECOVERY TECHNOLOGIES
Authors: Fialko N.M. , Navrodska R. , Shevchuk S. , Gnedash G.
Published: February 2025

The purpose of this study is to improve the operating modes of chimneys of gas-burning glass melting furnaces by applying the methods of their ecologization in systems for using the waste heat of furnace gases.
Known methods of thermal calculation of heat-exchangers and chimneys and methods for dispersing harmful emissions from thermal power plants in the environment were used. For the first time, the effectiveness of the proposed methods of greening to improve the conditions for dispersing harmful emissions from gas-burning glass melting furnaces in the environment under the conditions of using heat-recovery technologies has been studied. The results obtained will be used in the development of energy-efficient gas-burning thermal installations for technological purposes.
Computational studies have been carried out to improve the safety of operation of chimneys of regenerative-type glass melting furnaces by using technologies for recovering the waste heat of furnace gases using water and air-heating heat-exchangers and chimneys of various designs.
The influence of structural features of chimneys on their operating modes by using heat-recovery technologies with water and air-heating heat-exchangers is studied.
It is proposed to increase the environmental efficiency and operational reliability of chimneys by using the thermal method of bypassing a part of waste gases exhausted from regenerators past the heat-recovery equipment in heat-recovery technologies. An analysis of the effectiveness of this method to improve the ground-level concentrations of harmful emissions from furnaces by using the proposed heat-recovery systems was carried out. This method is more efficient for heat-recovery systems with water heat-recovery exchangers, is shown. Thus, with an increase in the share of waste-gas bypass from 0 to 40 %, the values of the coefficient showing the relative change in the maximum surface concentrations of harmful emissions increase to 6.5 % for heat-recovery systems with air-heating heat-exchangers and up to 30% by using water-heating heat-exchangers.
DYNAMICS OF SHOCK WAVE DEVELOPMENT IN VAN DER WAALS GAS
Authors: Avramenko A.A. , Dmitrenko N.P. , Kondrateva O.O. , Protsenko L.M.
Published: February 2025

The difficulty of studying flow passing through the supersonic threshold and the braking of supersonic flows is associated with the formation of shock waves of different shapes and structures. It cause breakdown of gas state parameters. A shock wave is a strong nonlinear disturbance that travels at supersonic speeds. Under this type of disturbance, the main physical characteristics of the flow (temperature, density, pressure) are breaking, passing through pressure jump.
In this paper changing of the Van der Waals gas flow parameters are analytically considered where stream passes through the normal pressure jump. Namely, the influence of the degree of compression of real gases and Van der Waals constants on the shock adiabatic are investigated. The modified Rankine-Hugoniot conditions are used for the analytical study of changing the parameters of the Van der Waals gas flow.
An increase in the parameter B of the van der Waals model contributes to the shift of the shock adiabatic towards smaller values. Analysis of the effect of parameter A of the van der Waals model on the behavior of the shock adiabatic showed a slowing down of pressure growth in the shock wave. Limit values of parameter Acr, above which the proposed calculation method becomes unusable, have been determined. It is shown that the limiting value of the parameter Acr is affected by the parameter B. An increase in the parameter B contributes to the expansion of the range of values of the parameter Acr. It is range, in which the proposed model, adequately describes the physics of the process.
The obtained analytical solutions also make it possible to estimate the influence of parameters A and B on the flow rate. Increasing parameter A, as well as parameter B, leads to a slight increase in the speed jump.
RESEARCH OF THE CAUSES OF PIPE DESTRUCTION IN HEAT EXCHANGER APPARATUS
Authors: Demchenko V.G. , Pogorelova N.D. , Khomenko M.V.
Published: February 2025

This article is devoted to issues of accident prevention and safe operation of tubular heat exchangers.
The purpose of the work is to identify and investigate the most common causes of damage and destruction of tubular heat exchange surfaces used in shell-and-tube heat exchange devices (hereinafter referred to as TA) and further provide recommendations for preventing their damage and destruction.
The object of research is pipe heat exchange surfaces.
The subject of research is the causes of damage and destruction of pipes of heat exchangers.
The most common causes of damage and destruction of the TA pipe surface can be grouped by technological, technical and production factors.
Consider the issue of choosing the materials of the pipe bundle, the quality of its installation and fastening. An analysis of the influence of the pipe geometry was made. For the first time, the question of the impact of pipe bending on the safe operation of the heat exchanger was formulated. The procedure for calculating the coolant flow rate and operating pressure is given.
Consider the issue of tube vibration, which is caused by vortex shedding. An example of ignoring the phenomenon of turbulent buffeting, which led to the destruction of the pipe bundle, is given. Examples of pipe destruction of a shell-and-tube heat exchange device from the real practice of its improper operation are given.
A systematic approach to solving problems of failure of heat exchange equipment, setting priority scientific and technical tasks in its design and operation has been formed.
The main causes of damage to pipes and their subsequent destruction have been determined, which include: design and manufacturing errors, use of inappropriate materials, changing the location of the pipe bundle without taking into account vibration and buffeting, mechanical damage during transportation and installation, non-compliance with operating rules.
Scientifically based recommendations on the prevention of emergency situations during the operation of the heat exchange apparatus are offered.
CFD - ANALYSIS OF THE THERMAL AND HUMIDITY STATE OF THE NEW SAFE CONFINEMENT AT THE CNPP BASED ON OPERATIONAL DATA
Authors: Krukovskyi P.H. , Smolchenko D.A.
Published: February 2025

For the first time, modeling of the non-stationary thermal and humidity conditions of the New Safe Confinement (NSC) at the Chernobyl Nuclear Power Plant was conducted (based on the development of the author's work [1]) using monthly operational data (temperature, humidity, and fan flow rates) within the NSC volume, taking into account changing climatic conditions (temperature, humidity, wind speed, and direction) over the course of a month. Additionally, the operation of special dehumidification units to maintain air humidity within the circular space (CS) of the NSC (with a volume of approximately 1 million m3) at no more than 40% over a 100-year period was considered. Operational temperature and humidity values at 8 local points at the inlet of the recirculation circuits in the CS were used to determine the temperatures and humidity at the outlet of the dehumidification units through 16 supply pipes of dehumidified and heated air with specified flow rates into the CS volume. These temperatures and humidity levels from the dehumidification units were achieved by minimizing the quadratic criterion of matching model and operational values at the aforementioned 8 local points for all 677-time moments, allowing for detailed three-dimensional non-stationary temperature and humidity fields throughout the CS volume. An analysis of these fields over a period of 28 days revealed humidity values exceeding 40% in areas where humidity sensors were absent. It was demonstrated that such exceedances could be addressed by including specific recirculation circuits. Thus, it is shown that only with the help of such models and continuous acquisition of operational data, it is possible to control temperature and humidity variations over time throughout the CS volume, which is the objective of this work. The possibility of using the models to prevent humidity values from exceeding 40% through optimal control of the NSC's humidity conditions using dehumidification units is considered.
ANALYSIS OF DIRECTIONS FOR INCREASING THE COMPETITIVENESS OF SECOND GENERATION BIOFUELS
Authors: Zheliezna T.A. , Drahniev S.V.
Published: February 2025

The purpose of the work is analysis of measures aimed at reducing the production cost of second-generation biofuels (advanced biofuels), as well as elaboration of recommendations for Ukraine on the development of this area. One of today's challenges is decarbonization of the transport sector. Among other things, this can be achieved by replacing traditional petroleum fuels with biofuels. At the same time, the biggest effect of decarbonization can be achieved from the use of advanced biofuels, as they provide a significant reduction in greenhouse gas emissions. The current global production volumes of second generation biofuels are ten times lower than that of traditional biofuels from food and feed feedstock. This is due to the complexity of production technologies and high cost of advanced biofuels. Right now, there are ways to reduce the production cost of second-generation biofuels, which can be divided into medium and long-term measures. The use of cheap feedstock, reduction of capital and operating costs and more efficient use of by-products are classified as medium-term measures that can be implemented within 10…15 years. Other measures, for example, learning lessons from the operation of previous installations, are considered long-term, which will be implemented over a period of more than 15 years. One of the means for reducing the cost of second-generation biofuels is co-location and integration of advanced technologies in existing fuel or industrial production infrastructures. In Ukraine, this can be implemented by integrating the production of advanced bioethanol in existing modern plants for the production of traditional bioethanol. Research and development work on optimizing and increasing the efficiency of lignocellulosic bioethanol production was carried out at the Institute of Engineering Thermophysics, Institute of Cell Biology and Institute of Food Biotechnology and Genomics of the National Academy of Sciences of Ukraine. Implementing findings of domestic researchers will contribute to the improvement of technologies for the production of advanced biofuels and the reduction of their cost.
MODEL OF HEAT AND MASS TRANSFER THROUGH THIN PARTIALLY PERMEABLE WALLS
Authors: Krukovsky P. , Diadiushko Ye.
Published: February 2025

The model under consideration addresses the transfer of heat and mass (air) through thin walls, described as partially permeable, which are composed of numerous impermeable metal sheets joined together by seams that are not entirely airtight and are permeable to mass. Such walls are found in large industrial facilities in the form of roofs and shells, covering areas of tens of thousands of square meters with metal sheets and tens of kilometers of seams between them. Therefore, modeling the transfer of heat and mass through these thin walls, which are subject to pressure differentials, poses a significant challenge not fully addressed by current CFD models. While modeling the part of heat transfer across the general surface area of thin walls is relatively straightforward, accurately modeling the transfer of mass and heat fraction through the numerous seams between sheets is problematic with CFD technology.
This work proposes a method for calculating mass flowrates and the heat fraction through the seams between sheets, distributing it across the entire surface area of the wall according to the signs and values of local pressure differentials between the calculation cells on both sides of the wall. It is noted that while a porous wall model could be used for such purposes, it does not account for the conjugate and radiative heat exchanges between both surfaces of such a wall with airflows and other walls. Unlike this approach, the proposed model incorporates conjugate and radiative heat exchanges and can also accommodate a wall of zero thickness, significantly reducing the number of cells in the main model required for CFD simulation. This submodel has been verified on number of simplified cases and currently applied to simulate air and moisture exchange through the inner and outer shells of the New Safe Confinement of the Chernobyl Nuclear Power Plant.
EXPERIMENTAL STUDY OF HEAT EXCHANGE DURING FORCED WATER FLOW IN A VERTICAL STEAM GENERATING CHANNEL
Authors: Tyrinov A.I. , Antipov V.G , Kovetskaya M.M. , Dmitrenko N.P. , Protsenko L.M
Published: February 2025

Measurements of heat transfer during boiling water in a vertical heated pipe with a diameter of 13 mm and a length of 2.6 m were carried out. The studies were carried out in the range of pressure changes from 4 MPa to 16 MPa, mass velocity from 120 kg/m2s to 2000 kg/m2s, heat flow from 0.13 MW/m2 to 2.59 MW/m2. The region of developed boiling was studied in the range of changes in vapor content from 0 ≤ x ≤ 1.
Experimental results show that mass velocity does not have a significant effect on the heat transfer coefficient. With increasing pressure, the heat transfer coefficient increases.
An equation has been obtained that describes the dependence of the heat transfer coefficient on the flow parameters and heating intensity. It is shown that in the region 0 ≤ x ≤ 1 the heat transfer coefficient smoothly decreases with increasing vapor content.
An increase in the heat transfer coefficient before the heat transfer crisis is observed in some modes at high values ​​of steam content. Qualitatively, this result is consistent with the experimental results [7] and is explained by an increase in the convective component of the boiling process in the dispersed ring mode when the near-wall liquid film is depleted.
FEATURES OF THE PRETREATMENT OF WHEAT STRAW FOR HYDROLYSIS
Authors: Bulii Yu.V. , Sydorenko V. V.
Published: February 2025

One of the stages of the complex processing of plant raw materials is the separation of lignin and hemicellulose from the lignocellulosic complex, followed by obtaining valuable chemical products or fuel from it.
This stage is an integral part of the pretreatment of raw materials for hydrolysis. But this stage is the most energy-consuming of the fuel ethanol obtaining, and aims to destroy the stable structure of cellulosic biomass and make cellulose more accessible to enzymes that convert carbohydrate polymers into fermentable sugars.
High energy costs of pretreatment of raw materials for hydrolysis are because this process takes place at high temperatures and pressure.
The work aimed to compare the effect of temperature, alkali concentration, and treatment duration of alkaline solutions of wheat straw by two methods of alkaline pretreatment on the process of lignin removal during preparing of raw materials for hydrolysis.
It was determined that increasing the alkali concentration from 0.5 to 4% reduces the lignin content in the sample to 4.17% of the total amount of solids for autoclaving at 90 ºС, at 121 ºС the amount of lignin content decreases to 2.98%. Processing at a temperature of 90 ºС reduces the lignin content to 3.15%.
The processing duration of affected the process of pretreatment as follows. The minimum lignin content   in the sample for autoclaving at 90 ºС for 60 min of treatment was 4.12% of the initial one. The minimum lignin content in the sample at 121 ºС was observed for one hour and made up 3.15%. Processing in a rotor-pulsation apparatus leads to a lignin content in the sample of up to 2.98% in 120 minutes.
The lignin is the most effectively removed in the temperature range of 80-121ºС. The minimum lignin content in the sample for autoclaving was 2.98% at 121 ºС. For processing, the maximum value of removed lignin was 3.15% at 90 ºС.
RESISTANCE OF TRANSPARENT STRUCTURES TO EXPLOSION INFLUENCES. OVERVIEW OF RESEARCH METHODS AND ANALYSIS OF INDIVIDUAL RESULTS
Authors: Basok B.I. , Nedbailo O.M.
Published: February 2025

The paper analyzes the potential of numerical modeling of the destructive impact of explosions from the point of view of its application to enclosing structures (including translucent ones). For the most common methods, a brief comprehensive theoretical basis with requirements, implementation and corresponding examples of results is given. In addition, the interpretation of the measurements is given. Separate simplified mathematical models, basic discretization schemes of the obtained values of the determining variables and calculation results are presented in combination with abbreviated descriptions of the main parameters of the materials of the fencing structures.
After the blast wave modeling process, it is necessary to estimate the response parameters of the translucent structure and the corresponding error in determining the factors affecting it. Recommendations from the above standards, based on the definition of a specific variable representing the structural deformation of the structure, should be applied.
The determination of the critical pressure for a specific structure is tied to the determination of the critical distance at which the structure cannot withstand the destructive impact of the shock wave.
The work was carried out with the assistance of the National Research Fund of Ukraine. The materials of the article contain the scientific results obtained as part of the implementation of the project No. 208/0172 "Aerodynamics, heat exchange and innovations to increase the energy efficiency of window structures and their use for the reconstruction of war-damaged buildings of Ukraine" competition "Science for the reconstruction of Ukraine in the war and post-war periods".