GLOBAL WARMING – PHYSICS AND GEOPOLITICS (Review). 4. Climate service in energy

Introduction. Reducing the negative impact of global warming on the economy and adapting to its devastating effects remains an important global challenge. Its solution is actively taken care of by politicians, the world's leading scientific organizations and the expert community. Problems. Economic, innovative and social approaches and measures to reduce and / or neutralize climate change, as well as adaptation to warming are considered. A new direction has been formed - climate service of world energy. Goal. Assess the state of the problem, present measures and tools for their implementation to reduce greenhouse gas emissions and / or adapt to their negative impact, in particular, in the field of energy using the GFCS approaches. Materials and methods. Authoritative recent literature sources with analysis of approaches, measures and tools to reduce greenhouse gas emissions have been used. Results. The experience on development and use of innovative technologies of climatic service in power on the basis of GFCS is resulted. Conclusions. Undoubtedly, the physics and geopolitics of global warming have become one of the most pressing transdisciplinary problems in the realities of the modern world. It is necessary to develop and deepen the scientific basis for the adaptation of life and economy to possible climate change and its consequences. It is important to change the behavior of society in an adequate attitude to the comfortable living conditions, in particular to its energy supply, and in general to a careful attitude to world resources, for example, on the basis of consistent implementation of the principles of sustainable development

CFD SIMULATION OF HEAT TRANSFER WITH SPIRAL-WIRE DISPLACEMENT ON THE PIPE

The results of the study of the intensification of the heat transfer process under forced air convection in the annular gap of a pipe-in-pipe heat exchanger with a spiral-wire intensifier located near the outer surface of the inner pipe are presented. The intensifier does not touch the pipe surface. The height of the wire of the intensifier is taken as 1.5 mm. The change in the winding pitch varied within the range of 12-20mm. Boundary conditions of the first kind + 20 ° C are set on the inner surface of the inner pipe. The temperature of the air moving in the annular gap is 300 ° C. The air velocity varied from 6 to 15 m / s. For the CFD model of a pipe-in-pipe heat exchanger, the use of a computational grid with 4.7 million elements is justified. The CFD model was validated using literature data. Based on the analysis of the ratio of the intensified Nusselt number to the Nusselt number for a smooth pipe, a 1.7-fold increase in heat transfer was found for Reynolds numbers from 5000 to 7000. This result is explained by the periodic destruction of the boundary layer along the pipe. With a further increase in Reynolds numbers to 13000, the intensification of heat transfer decreases from 1.7 to 1.3, which is explained by an increase in the vortex zone immediately behind the wire and the appearance of recirculation zones that make a minimum contribution to heat transfer. It has been determined that the spiral-wire intensifier with the maximum possible step of 20 mm contributes to the greatest increase in heat transfer by 1.7 times and has the smallest coefficient of hydraulic friction of 0.076-0.06 for the studied range of Reynolds numbers.

INVESTIGATION OF THE EVAPORATION AND CRYSTALLIZATION OF A SESSILE DROP OF AMMONIUM SULFATE SOLUTION ON A SMOOTH HEATED SURFACE.

Creation of new composite granular fertilizers with layered structure, which are formed due to the layered mechanism of granulation in the granulator of the fluidized bed is an urgent task. The process of forming these granules is achieved due to the layered granulation mechanism, the basis of which is the formation of a layer of solids on the surface of the granules by mass crystallization. In the production of granular fertilizers based on ammonium sulfate with the addition of organic and inorganic impurities an important place is occupied by the processes of evaporation and mass crystallization, which determine the morphological properties of the obtained granular material. During the experimental study of the evaporation process, it was found that the process consists of three main evaporation periods: the heating period from the initial temperature to equilibrium, the period of equilibrium evaporation and the decreasing drying rate period with crust formation, during which a solid crystal structure is formed. The beginning of each period according to the example of drying droplets in a gas stream during spray drying is described by the nature of the change in droplet temperature. This paper presents the obtained thermograms of the process of evaporation of droplets with a diameter of 3–7 mm 40%, 50% and 60% aqueous solutions of ammonium sulfate with the addition of a mixture of bone meal. The evaporation of 40%, 50% and 60% solutions of ammonium sulfate with the addition of a mixture of bone meal, with a given ratio of AS: BM on a dry residue of 60:40 and 80:20 on a surface temperature of 95°C in the second evaporation period crystalline nuclei appear, and the concentration of solute is close to saturated and almost unchanged, so that the evaporation rate and temperature of the drop, as can be seen from the thermogram, remain constant temperature for all solutions of ammonium sulfate. Increasing the content of bone meal from 8 to 24% to shift the wet thermometer in the kinetics of the evaporation process. The paper also presents the results of morphological analysis of the obtained solid crystallized drops of ammonium sulfate with impurities of bone meal. It was found that the solid crystallized drop of ammonium sulfate with bone meal consists of a framework of microcrystals of ammonium sulfate, with a reduced size of 10 to 80 μm, bone meal in the form of inclusions is placed in the frame, the particle size of bone meal varies up to 100 μm, indicating that the solution is a suspension.

FEATURES OF WATER TREATMENT FOR BOILER ROOMS

Thousands of medium and low steam boilers and hot water boilers operate in the country's industry, municipal energy and agriculture. Their reliable operation is largely determined by the maintenance of a rational water-chemical regime. The main problems of source water are the presence of dissolved oxygen, iron ions, salts of calcium, and magnesium. The aim of the work is to analyze the existing technologies and equipment for water treatment for different types of boilers. Determination of physicochemical parameters and requirements for source and prepared water. Presentation of new multi-purpose energy-efficient and resource-saving water treatment equipment. The article considers the negative impact of dissolved iron, hardness salts, dissolved gases present in the feed water on the operation of boiler equipment. The main requirements for feed water in terms of hardness, the content of dissolved oxygen, and oils for steam and hot water boilers are given. The mechanism of scale formation is given. The main existing methods of feed water treatment are considered, namely softening on Na-cation exchange resin, liming, softening, and reduction of total salt content on reverse osmosis units, softening, and reduction of total salt content by the sequential passage of water through H, OH-ion exchange filters. A multi-purpose aeration-oxidation setup of rotor type (AORT) is presented, which implements the method of discrete-pulse energy input, on which it is possible to carry out operations to remove iron, manganese, hardness salts, increase pH and degassing from water.

ADSORPTION OF OBSOLETE SLUDGE, PEAT, BUCKWHEAT HUSKS AND COMPOSITIONS FROM THEM

The problem of accumulation of obsolete silt deposits at aeration stations is relevant for the whole territory of Ukraine. This can lead to environmental hazards. Therefore, the task of processing silt deposits with the creation of granules based on them with the addition of peat and buckwheat husks. Van Bamelen's tensometric (static) method was used to determine the equilibrium humidity of the experimental samples depending on the relative humidity . As a result of researches kinetic curves of adsorption over obsolete silt deposits, peat, buckwheat husk and the three-component composition created on their basis are received. Kinetic adsorption curves indicate a slow process. The adsorption curves of the three-component composition have the character of curves of obsolete sludge, which have a non-uniform character. The obtained equilibrium humidity does not exceed the standard humidity for fuel pellets. The adsorption isotrams of the three-component composition and its components are determined, from which the equations of experimental and linearized isotrams are obtained. The analysis of experimental isotherms allows to relate them relatively to the isotherms of adsorption IV, which are observed in inorganic oxides and in other porous bodies. For the first time, the adsorption properties of three-component compositions based on peat, sludge and buckwheat husk were studied. The obtained equilibrium humidity of the compositions does not exceed the standard humidity for fuel pellets (is 20%) and is 6 - 7%. Therefore, they can be used for combustion in biomass boilers. The resulting ash can be used for the production of bricks, cement and other building materials. During storage of composite granules in order to prevent loss of their technological properties, it is recommended to maintain humidity at the level of 60 - 70%.

AERODYNAMICS AND HEAT EXCHANGE OF SINGLE END TUBE DURING EXTERNAL FLOW

In Ukraine, the safety of modern thermal power plants depends on the reliable operation of the equipment installed on them. Unfortunately, the technical condition of the chimneys is not properly maintained. Of course, the modernization of basic equipment (boilers, switching to another type of fuel) leads to a decrease in the temperature of the exhaust gases. An important aspect to maintain the condition of the chimneys is to maintain the moisture of the exhaust gases. An important feature of the external flow of chimneys are large Reynolds numbers Re = wd/n, which reach 106 and more. In the thermal calculation only the average heat transfer coefficient on the outer surface of the pipe is usually determined, and the features of aerodynamics and local heat transfer due to the conicity of the pipe are not taken into account. The work is devoted to the study of aerodynamics and heat transfer in the air flow of a single conical chimney. The method of computer modeling with numerical integration of equations of motion and energy was used in the research. At the first stage, the single pipe with the uniform flow profile is considered. Further, the influence of the surrounding infrastructure on the aerodynamics and heat transfer of a single conical tube is studied. The single conical vertical pipe with 40 m height, 1.7 m diameter at the base and 0.85 m in the mouth was used for the calculation. The computer model was calculated in the ANSYS2020-R1 program. The model is developed in a homogeneous area with the air environment. In order to obtain reliable results, the study was conducted to obtain the optimal set of the grid parameters for the heat transfer conditions. The grids with parameters that affect the distance of the first node from the cylinder wall (options a, b, c, d) and the rate of increase in the size of the elements as they move away from the area of interest (Growth rate GR) were studied. The type of the cylindrical pipe with constant diameter of 1.7 m has been chosen to analyze the sensitivity and to check the grid. The turbulence model has been choosen as the following: RNG k-ε model which is common for the tasks of this class, the Enhanced Wall Function, the solution algorithm for the connection of the velocity pressure in stable flows Simplex. It is determined that in case if the distance between the first node from the cylinder wall and the area of interest (Growth rate GR) is more than 8 mm, instability and deviation of the obtained data from the values of the average coefficient of more than 20% appears. As a result of the research, the parameter grid area matching to the “2d” option of table 1 has been selected, i.e.: GR = 1.1, h = 8 mm. In the study of aerodynamics and heat transfer, the conical tube is conventionally divided into 22 sections (with 1 m height each). The case of uniform flow velocity in front of the pipe has been considered. As seen, the maximum value of the heat transfer coefficient is in the Zone(21-22). The research shows that oncoming flow velocity of 25 m/s causes the average value of heat transfer coefficient of the conical pipe 62.5 W/m2K, and 61.1 W/m2K according to the known formula . This indicates a small effect of taper on the average heat transfer of the entire pipe. In the calculations, three types of surrounding areas are considered: A - open coasts of seas, lakes and reservoirs, rural areas, including buildings less than 10 m high; B - urban areas, forests and other areas, evenly covered with obstacles higher than 10 m; C - urban areas with dense buildings with buildings higher than 25 m. Thus, the wind speed profiles for different types of terrain are nonlinear. The wind speed profile in front of the pipe (type of terrain) has a significant effect on the heat transfer coefficient. This confirms the need to take into account the type of terrain and the velocity profile in front of the pipe for local heat transfer.

CFD MODELING OF VORTEX AFTERBURNING OF BIOMASS GASIFICATION PRODUCTS IN A FLUIDIZED BED FURNACE

CFD modeling of the afterburning of biomass gasification products in a fluidized bed furnace with a vortex supply of secondary air has been carried out. The effect of secondary air heating on the ecological characteristics of flue gases has been determined. Modeling has shown that gasification products swirl in the primary chamber with the formation of a central vortex, which obeys the law of solid-body rotation. An increase in the temperature of the secondary air leads to an increase in its tangential velocity and, as a consequence, to an increase in centrifugal mass forces. Calculations have shown that with an increase in the secondary air temperature, the maximum of the kinetic energy of turbulence shifts to the periphery and increases in absolute value. This results in more efficient mixing of the central (producer gas) and peripheral (secondary air) streams. As a result, this leads to a more complete combustion. The influence of secondary air heating on the ecological characteristics of the furnace has been determined. As a result of air heating from 30° C to 300° C, the concentration of carbon monoxide decreases by more than 1.5 times. The concentration of nitrogen oxides practically does not change and amounts to 3.5 mg /nm3.

INNOVATIVE METHODS OF JOINT PROCESSING OF HEAD AND FUSEL FRACTION IN RECTIFIED ALCOHOL END BIOETHANOL PRODUCTION

With rising energy prices, the development and implementation of innovative energy-saving technologies is a priority in the production of rectified alcohol and bioethanol. By-products of distillation are the head fraction of ethyl alcohol, fusel oil, and fusel alcohol. Existing methods of joint processing of the head and fusel fractions in one column do not provide effective removal together head and intermediate impurities, which adversely affects the quality of commercial alcohol. The aim of the work was to develop methods of joint processing of the head and fusel fractions in the column for the concentration of impurities of cyclic action, to determine the optimal technological parameters of the column, and to test the efficiency of innovative methods in production conditions: to determine the degree of extraction, the concentration of volatile impurities Three schemes of processing of the head and fusel fractions are given. The method I allowed to free the bottom products from the head and intermediate impurities of alcohol and use such a liquid for hydroselection in the epuration column. Method II allowed significantly improving the physicochemical parameters of the bottom water-alcohol products, improving the quality of rectified ethyl alcohol by more complete removal of volatile organic impurities from the zones of their maximum accumulation and reducing their content in the reflux entering the irrigation column. Method III allowed ensuring maximum removal of volatile head and intermediate impurities and reducing the loss of ethyl alcohol with the concentrate of impurities. The use of innovative methods allows for joint processing of the main and fusel fractions in the production of rectified alcohol and bioethanol, to increase the yield of marketable alcohol by 3.8%.

ANALYSIS OF THE HEATING CAPACITY OF ELECTRICALLY HEATED WINDOWS

Electric window heating has been used for some time in Europe and the Americas, but in Ukraine it only enters the market as an independent heating device and raises the question of its heating capacity in winter and the benefits of using them. There are several works in this field that determine the efficiency and contribution to the energy needs of an electric-heated window house, but it is necessary to answer more specifically the question of the heating capacity of such windows as a single heating system, for example rooms of certain sizes.In the work present the design, thermophysical processes occurring in such windows and, by computer simulation of the thermal state of the window with the selected typical room, the results of the study of the heating capacity of the windows, depending on the relative glazing area to the total area of the outer enclosure and the ambient temperature conditions not exceeding the maximum heat emission 450 / and temperature 45 °С on the inner glass of the double-glazed window. the presented thermal model of the window with the room is implemented as a computer program with the possibility of a detailed analysis of the heating capacity of the window, depending on the parameters of the room and the outside temperature, as well as optimization of operational parameters to maintain comfortable conditions.

GLOBAL PROSPECTS FOR BIOENERGY SECTOR

The aim of the work is to analyze some global scenarios for bioenergy development, including the development in certain sectors, as well as to identify priority areas for bioenergy in Ukraine. Today, bioenergy is a world leader in renewable energy, playing a significant role in replacing fossil fuels and reducing greenhouse gas emissions. Over the last twenty years, the global primary energy supply from biomass and biofuels has tripled and reached more than 10% of the total primary energy supply, accounting for almost 70% of the contribution of all renewable sources. The International Renewable Energy Agency predicts that by 2050, renewable energy sources could account for 60% or more of the total final energy consumption of many countries. The share of biomass in the global final consumption of renewable energy might be almost half in 2030 and 40% in 2050. According to the International Energy Agency, starting from 2030, one can expect to use only modern bioenergy technologies with increasing consumption of modern biomass up to about 100 EJ in 2050. For Ukraine, the priority areas seem to be combined heat and power production from biomass, as well as production of biomethane for the direct replacement of natural gas and carbon-neutral balancing of the energy system with a high share of renewable sources. For the thermal energy sector, the introduction of modern boilers and CHP plants running mainly on agricultural biomass is recommended. For the transport sector, prospects are the production of first and second generation liquid biofuels, as well as biomethane from biomass obtained in compliance with sustainability criteria.