Articles in "Energy"

Summary: Hydrogen technologies are rapidly penetrating all aspects of life, forming the basis of the Hydrogen Civilization of the future. Hydrogenated amorphous silicon (a-Si:H) thin films are widely used in solar cells due to their advantageous optical properties. Here are some key points about their optical characteristics: 1. Optical Band Gap: The optical band gap of a-Si:H can be tuned by adjusting the hydrogen content during deposition. This allows for better absorption of sunlight and improved efficiency in solar cells. 2. Refractive Index: The refractive index of these films is crucial for designing anti-reflective coatings, which enhance the amount of light entering the solar cell. 3. Urbach Energy: This parameter indicates the width of the tail of localized states in the band gap. Lower Urbach energy values are desirable as they signify fewer defects and better electronic properties. 4. Absorption Coefficient: High absorption coefficients in the visible spectrum are essential for thinfilm solar cells to absorb maximum sunlight with minimal material. 5. Hydrogen’s Role: Hydrogenation helps in passivating dangling bonds in the silicon network, reducing defects and improving the material’s optical and electronic properties. These properties make hydrogenated amorphous silicon thin films a popular choice for cost-effective and efficient solar cells. Infrared (IR) absorption spectra are investigated hydrogenated amorphous solid solution films a-Si1-xGex: H (x = 0 ÷ 1) plasma chemical vapor deposition at different partial pressures of hydrogen PH2. Defined force, oscillator, which essentially depended on PH2. It is shown that the hydrogen contained in films mostly in the forms of GeH, SiH. Using integrated acquisitions JW, determined the amount of hydrogen in the films. Film properties depend on the composition and level of hydrogenation. The number of hydrogen atoms in films, varied by changing the composition of the gas mixture. In the work measured IR absorption for films a-Si1-xGex: H, a-Ge:H and a-Si0,88Ge0, 12: H based on films and a-Si: H and a-Si0,88Ge0, 12: H fabricated three-layer solar cells with an area of item 1.3 cm2 and efficiency equal to ~9.5%.

Summary: Exactly 50 years have passed since the beginning of the active phase of hydrogen energy (since 1974). The start of hydrogen energy in the 20th century was given by the efforts of the Patriarch of hydrogen energy, Professor T. N. Veziroglu. In the early works of Professor T.N. Veziroglu, the direction of solar-hydrogen energy already appears as the cleanest energy for improving the quality of life on the planet. The development of solar energy is carried out fantastically quickly. In 2023, 428 GW of solar energy were added, which is 76% more than the same period last year, as a result of which the total installed solar capacity worldwide reached 1.6 TW. An important direction of the solar-hydrogen system is the work to increase the efficiency of solar photovoltaic panels. In this work, various parameters of films of amorphous and nanocrystalline silicon-carbon alloy (a-nc-Si1-xCx:H (x = 0–1)) doped with phosphorus (PH3) and boron (B2H6) are investigated. The properties of these films obtained on various substrates of quartz, glass and silicon with a coating of Fe, Al, Pd, Ni, Ti, Ag, are studied. The morphology of the obtained nanotubes is studied using transmission electron microscopy (TEM). The structural properties of the films are also studied using infrared spectroscopy and X-ray diffraction. Cascade solar cells with an area of S = 1.0 cm2 and an efficiency of 14.09% are created. Solar photocells made of amorphous and nanocrystalline silicon-carbon alloy currently have the highest warranty resource - up to 35 years. This allows for long-term investments in the use of land that has a low cost with high benefit. At the same time, a good basis is created for the intensive development of solar-hydrogen energy.

Summary: The article provides information on the creation and study of energy systems based on the power of air flows with maximum use of advantages in processes associated with nature. An analysis of available data in this area is carried out, the advantages and disadvantages of energy installations are indicated. Based on the analysis and theoretical considerations, the indicators of the model for improving the energy system using the power of the air flow, including economic efficiency, are analyzed. Changes in influencing parameters to improve the efficiency of using the design of the energy installation are described, a comparative analysis is given.

Summary: Thermomechanical processing is a combination of the operations of deformation by heating and cooling (in different sequences), as a result of which the formation of the final structure of a metal alloy, and consequently its properties, occurs under conditions of increased density and the corresponding distribution of structural imperfections created by plastic deformation. Therefore, firstly, research in the field of thermomechanical processing is reduced to studying the effect of plastic deformation on transformations in heat-treated alloys and on the structure in properties after these transformations. Secondly, thermomechanical processing is advisable in all cases where heat treatment of metal alloys is effective. Phase transitions during heat treatment and plastic flow occur as a result of the restructuring of the same atoms, connected not only by general regular structures, but also by certain, also to a certain extent regular, deviations from these structures, the main ones of which are dislocations.

Summary: In the article, two cylindrical shells with different dimensions are statically analyzed using the finite element method. Cylindrical shells with a height to outer diameter ratio (h/d=2) of two and four (h/d=4), and a wall thickness of 1 mm were selected as the research objects. Carbon steel grade 1023 was selected for the cylindrical shells. The cylindrical shells were rigidly fixed on one side (Fixed Geometry fastening type was selected), and free on the other side. A compressive force of 1000N was applied to the inner surfaces of the cylindrical shells. Static analysis was performed using the simulation application in the Solidworks program. As a result of the analysis, the distributed values of the Von Mises stress, normal stress along the x, y and z axes were obtained. At the same time, the distributed values of the total displacement along the x, y and z axes were obtained. The maximum values of von Mises stress, normal stress (along the given axes) and displacement were observed in the sample with a small diameter (d=25mm) and a large height (h=200mm) (h/d=4). A difference of 98% was obtained between the maximum values of stress and displacement in both samples.

Summary: This study focuses on the stabilization of residual stresses in welded structures of presses through pulse unloading prior to vibration treatment. Residual stresses in welded components can compromise structural integrity, reduce fatigue life, and lead to premature failure. The proposed approach involves applying controlled pulse unloading to redistribute and stabilize stress fields, creating a more uniform stress state before subjecting the structure to vibration. Experimental and analytical results demonstrate that the combination of pulse unloading, and vibration treatment significantly reduces peak residual stresses and improves the mechanical properties of welded assemblies. This method provides an efficient solution for enhancing the durability and performance of welded structures in industrial applications. The influence of various stabilizing treatments on the properties of steel welded samples is investigated. The efficiency of the vibration method with pulsed unloading for reducing the level of residual stresses in samples by 1.3-2.3 times and ensuring their geometric stability is demonstrated.

Summary: The article discusses issues of improving the operational properties of pressure and drilling compressor pipes. For oil and gas production, three main types of pipes are used: drill casing and tubing. Taking into account production requirements and the importance of this element in the chain of work carried out, the service life of oil country pipes is complex and varied. In oil-producing and exporting countries, the requirements for the main technical parameters of pipes used in the oil industry differ from the requirements in other areas, the pipes and pipe fittings used. Taking into account the above, pipes intended for the production and transportation of oil and gas must have the necessary performance properties in terms of performance, reliability and safety. At the same time, taking into account operating pressures and other environmental factors, the issue of improving the properties (strength and stability) of the material from which pipes are made, while maintaining mechanical characteristics, is relevant. Improving the properties of pipes, especially the mechanical properties, is an important and important issue. Therefore, you should first be careful when choosing the material from which the pipe is made. Because the material from which the pipe is made must be of high quality in terms of mechanical properties. Considering that pipes, especially those used for oil and gas transportation, carry material for large kilometers. That is, the pipes pass through deserted and empty areas. In other words, if there is a malfunction in them, it can result in the loss of the transported material, which is considered undesirable for the economy. In this regard, their properties, especially mechanical properties, should be high. Corrosion can occur in the part where liquid flows through the pipes, which can also be cavitation corrosion. Cavitation corrosion is also considered a defect for pipes.