• Energy Research
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• Sumy State University close

The problems of environmental pollution in the conditions of high dust content in the air during the development of coal mines in the territory of the Czech Republic are considered. A mechanism for making managerial decisions was developed using an integrated approach using the new technological process Nastup Tušimice (DNT) aimed at eliminating pollutant emissions and managing workers in dusty conditions in mining operations. The recommendations of active and passive measures aimed at reducing dustiness in the process of coal mining have also been developed.

The article deals with the theoretical description and experimental study of the hydrodynamic and heat transfer properties regarding the operation of multistage gravitational devices of the fluidized bed with inclined perforated shelves. The peculiarities of the work and the implementation field of the multistage shelf units are described. A theoretical model to define the solubilizer’s velocity above the perforation holes, in the above-shelf space of the device and in the outloading gap, as well as the residence time of the dispersed phase at the stage (perforated shelf contact) of the device is presented. The results of experimental studies regarding the influence, made by the structural parameters of the perforated shelf contacts, on the distribution pattern of single-phase and gas-dispersed flows in the workspace of the device, on the intensity of interphase heat transfer are presented. The conditions to create active hydrodynamic operating modes of multistage gravitational shelf devices, which provide higher efficiency of heat-mass transfer processes, and with lower gas consumption and hydraulic resistance compared to typical fluidized bed devices, are proved. Peculiarities regarding the implementation of heat-mass transfer processes in multistage devices are described using heat treatment and drying processes as examples.

The study focuses on the challenges of implementing fuel cell technologies and materials to achieve efficient use of green hydrogen and zero CO2 emissions. It is shown that only identifying the optimal parameters for each fuel cell component and technology and testing the system will help achieve the planned output-specific power. The thorough structure optimization of the membrane-electrode complex and testing in actual operating conditions will accelerate the implementation of fuel cell technologies. An example of structural optimization and improvement of catalytic activity of electrodes and electrolytes is shown. The current density of 0.36 μA/cm2 was obtained at a voltage of 0.6 V and a temperature of 500 °C for the fuel cell with 75–80 μm thick ZnO electrolyte and without membrane electrode assembly optimization. It is shown that the fuel cell electrodes’ catalytic activity depends on the modeling profile and structure of the catalytic layer, which was verified by testing in real fuel cell operating conditions.

Despite the rapid development of alternative energy sources, the role of hydrocarbons in the global fuel and energy balance remains significant. For their transportation and further processing, pre-processing is carried out using a set of equipment. In this case, the mandatory devices are separators. In terms of specific energy consumption and separation efficiency, methods based on the action of inertia forces are optimal. However, standard designs have common disadvantages. A method of dynamic separation is proposed to eliminate them. The proposed devices are automatic control systems. The object of regulation is hydraulic resistance, and elastic forces are the regulating actions. Aerohydroelastic phenomena accompany the operation of dynamic separation devices. Among them, the most interesting are flutter and buffeting. Oscillations of adjustable baffles accompany them. It is necessary to conduct a number of multifactorial experiments to determine the operating parameters of dynamic separation devices. In turn, physical experiments aim to identify patterns and features of processes occurring during vibration-inertial separation (i.e., the dependence of various parameters on velocity). Therefore, the article proposes a methodology for carrying our physical experiments on dynamic separation and a designed experimental setup for these studies. As a result, the operating modes of separation devices for different thicknesses of baffle elements were evaluated. Additionally, the dependences of the adjustable element’s deflections and oscillation amplitudes on the gas flow velocity were determined for different operating modes of vibration separation devices.

This paper focuses on the study of the effect of electrolysis on activated sludge in a microbial electrolysis cell (MEC) under the anaerobic digestion of poultry manure. This study was conducted using a bioreactor design with and without electrodes (conventional condition). Measurements of pH, redox potential (ORP), and total dissolved solids were carried out, as was the microscopy of activated sludge during treatment and gasometry. There was an increase in the yields of CH4 and CO2 compared to conventional conditions. Thus, on the 14th day, there was an increase in the CH4 yield to 35.1% compared with the conventional conditions—31.6%—as well as in the CO2 yield to 53.5% compared with the cell without electrodes—37.7%. Visually, the microscopy of anaerobic activated sludge showed changes in the aggregation process itself, with the formation of cells of clusters of microorganism colonies with branches of a delineated shape. ORP fluctuations were related to the process of the dissociation into ions during the passage of an electric current through the electrodes, and were observed before and after the inclusion of a current into the system. A model of the effect of electrolysis during anaerobic digestion was developed, taking into account the influencing factors on the condition of the activated sludge.

This article is devoted to modeling, researching and optimizing the main properties of an environmentally clean polymer composition based on oligofurfuryloxysiloxanes (OFOS), which can be used to produce casting molds and cores in the production of castings from ferrous and nonferrous metals. Polymer compositions were examined for strength, survivability, gas permeability, moisture, crumbliness, fire resistance, knockout, and stickability. It has been established that the increase in the strength of the polymer composition over time obeys an exponential law. Mathematical equations were derived for all the exponential curves. The indications of compressive strength of the polymer composition with OFOS with all the acid catalysts used were, on average, as follows: after 1 h—1.3–1.54 MPa; after 3 h—2.5–2.9 MPa; after 24 h—4.9–6.1 MPa, which meets the requirements for casting molds before pouring with metal. The use of polymer compositions with OFOS ensures environmental safety of the technological process, due to the lack of emission of toxic substances, both in the “cold” stage of the process and during casting with molten metal, cooling, knocking out, and disposal of polymer compositions. This makes it possible to save energy resources, and thereby reduce the total cost of the entire technological process and castings.

This paper elaborates on the theoretical and methodological fundamentals of a tradable green certificates system to foster renewable energy development in Ukraine. It proposes a management mechanism premised on the classical market model of tradable green certificates aiming at increasing the share of electricity from renewable energy sources in the country’s energy mix. Organizational stages of the mechanism formation at the national level and a methodological approach to assess green electricity generation cost are developed. The modeling has shown that the annual increase in the cap for green electricity consumption by 1% will raise the electricity tariff by 3%, which is not a significant financial burden for consumers. The proposed changes in the tradable green certificates system can be an effective management tool to achieve the required amount of electricity from renewable energy sources in the country’s total electricity consumption and to foster the development of the Ukrainian renewable energy sector.

The article deals with the study on the efficiency of units for porous ammonium nitrate production. The ways which increase the effective implementation of energy resources are determined by including the ejector recycling module, heat and mass exchangers that utilize principles of regenerative indirect evaporative cooling, and the sub-atmospheric inverse Brayton cycle. Mixed exergy analysis evaluates all flows of the system contour as those of the same value. The target parameter for determining the efficiency of both systems is the ratio of the unit’s productivity to the exergy expenditures to produce the unit mass of the product. As a result, it is found that the mentioned devices and units enable to increase the efficiency of the basic scheme by 87%.