THE CONCEPT OF MULTI-LEVEL MODIFICATION IN THE TECHNOLOGY OF HIGHLY FILLED FLUOROCOMPOSITES

The structural and technological aspects of obtaining composite materials based on polytetrafluoroethylene are considered. It is shown that due to the existence of inert components in the process of interfacial interaction with the degree of filling in the traditional technological paradigm implemented, structural paradox manifests itself in proportion to the reduction of the parameter of tensile strength with increasing degree of filling. According to the concept of multi-level modification, the technological principles are proposed to eliminate the negative impact of the structural paradox fluorine composites by controlling the structure of the organization at various levels – molecular, supramolecular, and interfacial phase. Efficient methods of manufacture of products from highly filled fluorine composites containing 25–35 wt. % carbon fiber with parameters of deformation and strength characteristics higher than the corresponding parameters of analogs.

Cement-polymer materials for well casing

The work shows the efficiency of using the SСADC reagent as an additive in cement-polymer mixtures. It also outlines physicomechanical properties of the cement slurry and the stone formed on their basis at temperatures of 22 C and 80 C. The main regularities of the formation of structures of various levels in cement-polymer solutions are revealed, depending on the degree of filling and the type of introduced modifications of the SСADC reagent. It was found that an entangled fibrous structure is formed between the hydrated cement minerals and the complex additive SСADC. At a concentration of 0.2%, it provides a self-healing effect for a damaged cement stone, and also improves the properties of cement-polymer grouting mixtures, contributing to a decrease in the filtration rate of the solution to 30%, an increase in bending strength by 25-27% and by 36-42% in ultimate strength for compression.

OPTIMIZATION OF THE DRYING PROCESS GRAIN CROP IN A TUMBLE DRYER WITH HEAT PUMP

Рассмотрена возможность автоматической оптимизации процесса сушки зернобобовых культур в барабанной сушилке с парокомпрессионным тепловым насосом по технико-экономическому показателю при выполнении ограничений на качество готового продукта. В качестве критерия оптимизации использованы суммарные энергетические затраты, приходящиеся на единицу массы испаряемой влаги. Определены три составляющие числителя критерия оптимизации: затраты на преодоление аэродинамического сопротивления слоя продукта в барабанной сушилке, затраты электроэнергии на привод компрессора парокомпрессионного теплового насоса (ТНУ), привод вращения барабана. Затраты электроэнергии на привод компрессора рассчитывали через холодопроизводительность ТНУ. Установлена зависимость разности влагосодержаний сушильного агента до сушки и после нее от степени заполнения сушильного барабана зернистым продуктом при различных значениях его начальной влажности. Получена однозначная функциональная связь суммарных энергетических затрат, приходящихся на единицу массы испаряемой влаги от степени заполнения барабана. На примере сушки зерна пшеницы в барабанной сушилке с профильной канальной насадкой, укомплектованной парокомпрессионным тепловым насосом, показана возможность управления степенью заполнения барабана по минимальной величине удельных энергетических затрат. Сочетанием экспериментальных и аналитических методов исследования разработана система экстремального управления процессом сушки зерна в барабанной сушилке с тепловым насосом, позволяющая с помощью микропроцессора осуществлять оперативный поиск оптимального значения степени заполнения барабана, что существенно снизит удельные энергозатраты на процесс сушки. При этом по текущей информации, получаемой с датчиков, микропроцессор непрерывно вырабатывает сигнал отклонения текущего значения степени заполнения от оптимального и посредством исполнительного механизма воздействует на расход влажного зерна, а следовательно, и на степень заполнения барабана продуктом, так чтобы суммарная удельная мощность энергооборудования для выбранного режима сушки была бы минимальной. Для многозонной барабанной сушилки предложенный алгоритм управления необходимо повторять для каждой из зон, в которых степень заполнения регулируется с помощью секторных заслонок. The possibility of automatic optimization of the drying process of legumes in a tumble dryer with a steam compression heat pump according to the technical and economic indicator when the quality of the finished product is limited. As an optimization criterion, the total energy costs per unit mass of evaporated moisture. Three components of the numerator of the optimization criterion are determined: the costs of overcoming the aerodynamic resistance of the product layer in the drum dryer, power consumption for the compressor drive of a steam compression heat pump (HPI), drum rotation drive. The energy costs for the compressor drive were calculated through the cooling capacity of the HPI. The dependence the difference in the moisture content of the drying agent before and after drying on the degree of filling the drying drum with a granular product is established for different values its initial humidity. An unambiguous functional relationship between the total energy costs per unit mass of evaporated moisture, the degree filling the drum. On the example wheat grain drying in a drum drier with a profile channel nozzle equipped with a steam compression heat pump, it is shown that it is possible to control the degree of filling of the drum by the minimum value of the specific energy costs. A combination experimental and analytical research methods developed a system for extreme control of the drying process grain in a drum dryer with a heat pump, allowing using the microprocessor to perform an operative search for the optimal degree of filling of the drum, which will significantly reduce the specific energy consumption for the drying process. At the same time, according to the current information received from the sensors, the microprocessor continuously generates a signal of deviation of the current value the filling degree from the optimal one and by means of the actuator it affects the consumption wet grain, and consequently, the degree of filling of the drum with the product, so that the total specific power of the power equipment for the selected drying regime would be minimal. For a multi-zone drum dryer, the proposed control algorithm must be repeated for each zone in which the degree of filling is controlled by sectoral dampers.

Establishing the conditions for the formation of a near-wall layer of solid granular fill of a rotating drum

This paper reports the assessment of the influence of dynamic motion parameters on the formation and disappearance at the cylindrical surface of the chamber of the rotating drum of the near-wall layer of non-loose granular fill. Based on the results of experimental visualization of the flow, the effect of solidity on the behavior of granular fill was revealed. The hydrodynamic effect of fill quasi-liquefaction under the action of solidity has been established, which involves the occurrence of a connecting interaction between adjacent layers and the surface of the chamber. Conversion of shear circulation flow to homogeneous dense clustered stream with slipping and rolling without relative movement of particles was detected. The hydrodynamic characteristics of circulation flow transition to the near-wall layer mode during rotation acceleration have been defined. Such a transition is implemented by smoothly increasing the thickness of the layer when the rest of the fill is circulated at the bottom of the chamber. The effect of the rheological hysteresis of the movement of the rotating chamber fill, caused by quasi-liquefaction of non-loose granular environment, has been established. The effect implies exceeding the speed limit ωfl in the formation of a near-wall layer, at rotation acceleration, above the boundary ωdl of the layer disappearance when the rotation slows down. The manifestation of hysteresis mainly increases with an increase in Reynolds number. The intensity of increased hysteresis manifestation increases with a decrease in the degree of filling the chamber. The value of the Froud number for the ωfl and ωdl boundaries increases with the increase in Re. It has been established that at the relative particle size of the dispersed fill ψdc≈(0.065–1.04)·10‑3 and Re=30–500, Fr=1–2.9, for the ωfl boundary, and Fr=0.5–1.4, for the ωdl boundary. The Fr value for the ωfl limit was found to exceed this value for the ωdl boundary by 1.6–2.1 times. The established effects make it possible to substantiate the rational parameters for the grinding process in drum-roll mills

New Copper Alloys Used to Make Products Intended for Contact with Drinking Water

This article presents the results of tests conducted as part of a research project with the primary objective of developing new copper alloys with limited lead content. The new group of materials were created in a production plant. As part of tests, a group of 22 alloys were selected for testing in castability, structural characteristics and hardness. Based on the test results obtained, the group of alloys under study was narrowed down to nine. The mechanical properties of these alloys were determined in static tensile tests as well as in uniaxial upsetting tests at elevated temperature, on the basis of which the group of alloys under investigation was further narrowed to three. Further studies involved technological verification of the application of these alloys under industrial conditions. These alloys were subject to numerical forging analyses, along with forging tests, under semi-industrial conditions, where the degree of filling of a die impression at a specific temperature was measured using an optic scanner. The quality of production of the obtained forgings was evaluated macroscopically with simultaneous observations of the microstructure.

Study of the rheological properties of the highly-filled paste-like fuel composition based on oligomeric rubber and dispersed fillers

We present the results of creation of paste-like fuel compositions with a high degree of filling (up to 90 wt.%) and investigation of their rheological properties. The developed composition contained the following components: a polymer matrix (type SNBR-N butadiene rubber) and a mixture of inorganic fillers (preliminarily surface-modified highly disperse potassium chloride, that was microencapsulated by using oligomeric products of polyehtyleneterepthalate glycerolize, and highly dispersed aluminum powder. A surface-active compound (oligomeric polioxypropylene glycol) and plasticizers of different natures were used as additional components, which were introduced in order to increase the degree of filling of the resulting paste-like compositions while maintaining a low level of their viscosity. The dynamic viscosity of the compositions was evaluated in the range of the shear stresses of 1 to 30 kPa and the temperatures of 293 to 323 K by using a rotary viscometer (cone–plane system). The viscosity of the composition which is a mixture of saturated and unsaturated methyl ester fatty acids at the maximum degree of filling (90 wt.%) was at the level of viscosity of the individual binder.

An Artificial Intelligence–Assisted Design Method for Topology Optimization without Pre-Optimized Training Data

Engineers widely use topology optimization during the initial process of product development to obtain a first possible geometry design. The state-of-the-art method is iterative calculation, which requires both time and computational power. This paper proposes an AI-assisted design method for topology optimization, which does not require any optimized data. An artificial neural network—the predictor—provides the designs on the basis of boundary conditions and degree of filling as input data. In the training phase, the so-called evaluators evaluate the generated geometries on the basis of random input data with respect to given criteria. The results of those evaluations flow into an objective function, which is minimized by adapting the predictor’s parameters. After training, the presented AI-assisted design procedure generates geometries that are similar to those of conventional topology optimizers, but require only a fraction of the computational effort. We believe that our work could be a clue for AI-based methods that require data that are difficult to compute or unavailable.

Analysis of factors affecting the efficiency of thermosyphones

The paper provides a review and analysis of research works aimed at studying the factors that affect the efficiency and reliability of closed two-phase thermosyphons as heat utilizers of heat technological emissions. Factors such as the geometric characteristics of thermosyphons and their ratio, the angles of inclination of the evaporation and condensation surfaces, the degree of filling of the thermosyphon pipe, the state and physical properties of the evaporation and condensation surfaces, the influence of acoustic and vibration influences on the efficiency of heat and mass transfer, as well as their use in as working bodies of nanofluids.

Influence of Detonation-Spraying Parameters on the Phase Composition and Tribological Properties of Al2O3 Coatings

Al2O3 coatings were applied on the surface of 12Ch18N10T steel by the detonation method at different degrees of filling of the detonation gun. The aim was to study the influence of technological parameters on the formation of the coating’s structure, phase composition and tribological characteristics. The degree of filling the gun with a gas mixture (C2H2/O2) varied from 53% to 68%. X-ray diffraction study showed that the content of α-Al2O3 increases depending on the degree of filling. The results showed that the hardness increases with an increase in the α-Al2O3 phase. When the gun is 53% filled with gas, the Al2O3-based coating has the hardness of 20.56 GPa compared to 58%, 63% and 68% fillings. Tribology tests have shown that the wear rate and friction coefficient of the coating is highly dependent on the degree of filling of the gun.

Obtaining multilayer coatings by the detonation spraying method

This work were studied the effect of technological parameters of detonation spraying on the phase composition and tribological characteristics on the bases of NiCr and Al2O3 coatings. As well as there was obtained and investigated multilayer coating on the bases of NiCr/NiCr- Al2O3/Al2O3 . It was determined that during detonation spraying the phase composition of Al2O3 coatings strongly depends on the degree of filling the borehole with a gas mixture. The a - Al2O3 -phase content in the coatings increases when the degree of filling is 63% and 54%. Only one CrNi3 phase is observed on the diffractograms and only increase of reflex intensity (020) at barrel filling by 58% is observed by sputtering on the bases of NiCr coatings in different degrees of barrel filling. The results of the coating nanohardness study showed that the hardness of the Al2O3 coating increases depending on the content of a- Al2O3 in it. Al2O3 coating has the maximum nanohardness values and is 16.42 GPa at the borehole is filled to 63%. The nanohardness of NiCr coating has the maximum values at barrel filling by 58% and consisting of 8.02 GPa.