We describe the external and internal hydrogen interaction on contacting surfaces in the “cylinder–piston rings” friction coupling. Under the influence of high temperatures and pressure, the oil in the combustion chamber at a temperature up to 1473 K decomposes and forms small amounts of water. External hydrogen (H₂) is subsequently formed. Hydrogen removal from the piston rings reduces the heterogeneity of the structure, residual stresses, and uneven physical and chemical properties of the near-surface layers, which reduces the stress concentration and, as a consequence, results in an improvement in the performance characteristics of the surface layers of the friction couple “cylinder-piston rings” of the spark ignition engine.

This article is devoted to the following issues: calculating the values of temperatures obtained by simulating welding heating and the subsequent implementation of the welding process at the given mode parameters made it possible to obtain a welded joint of the rotor with an improved initial structure and increased mechanical properties, hydrogen resistance and durability by up to 10–15%; simulating welding heating in the areas of fusion, the overheating and normalization of the HAZ and the formation of austenite grains; specified welding heating creates the conditions for the formation of new products of austenite decomposition in the form of sorbitol in the area of the incomplete recrystallization of the HAZ. In air and gaseous hydrogen, the destruction of the combined joints took place on the weld metal, as well as on the fusion areas, the overheating and the incomplete recrystallization of the HAZ of 20H3NMFA steel as the base metal. Structural materials have a relatively low strength and high fracture toughness in air. This is manifested in a significant reduction in the elongation (δ), the area (ψ) and critical stress intensity factor (K_Ic) of welded joints and the endurance limit of cylindrical smooth rotor steel specimens, which were cut from transverse templates. Welded joints in the whole range of load amplitudes are sensitive to the action of hydrogen.

The article is devoted to the following issues: boiling of fluid in the cooling jacket of the engine cylinder head; agents that influenced the thermal conductivity coefficient of nanofluids; behavior of nanoparticles and devices with nanoparticles in the engine’s cylinder head cooling system. The permissible temperature level of internal combustion engines is ensured by intensification of heat transfer in cooling systems due to the change of coolants with “light” and “heavy” nanoparticles. It was established that the introduction of “light” nanoparticles of aluminum oxide $A{l}_2{O}_3$ $A{l}_2{O}_3$ into the water in a mass concentration of 0.75% led to an increase in its thermal conductivity coefficient by 60% compared to the base fluid at a coolant temperature of 90 °C, which corresponds to the operating temperature of the engine cooling systems. At the indicated temperature, the base fluid has a thermal conductivity coefficient of 0.545 $\frac{W}{\left(m^2\times °\mathrm{C}\right)}$ W/(m °C), for nanofluid with $A{l}_2{O}_3$ particles its value was 0.872 $\frac{W}{\left(m^2\times °\mathrm{C}\right)}$. At the same time, a positive change in the parameters of the nanofluid in the engine cooling system was noted: the average movement speed increased from 0.2 to 2.0 m/s; the average temperature is in the range of 60–90 °C; heat flux density 2 × 10²–2 × 10⁶ $\frac{W}{m^2}$; heat transfer coefficient 150–1000 $\frac{W}{\left(m^2\times °\mathrm{C}\right)}$. Growth of the thermal conductivity coefficient of the cooling nanofluid was achieved. This increase is determined by the change in the mass concentration of aluminum oxide nanoparticles in the base fluid. This will make it possible to create coolants with such thermophysical characteristics that are required to ensure intensive heat transfer in cooling systems of engines with various capacities.

This article presents a theoretical analysis of the use of spiral-elliptical ducts in the atomizer of a modern fuel injector. The parameters of the injected fuel stream can be divided into quantitative and qualitative. The quantitative parameter is the injection dose amount, and the qualitative parameter is characterized by the stream of injected fuel (width, atomization, opening angle, and range). The purpose of atomizer modification is to cause additional flow turbulence, which may affect the stream parameters and improve the combustion process of the combustible mixture in a diesel engine. The spiral-elliptical ducts discussed here could be used in engines powered by vegetable fuels. The stream of such fuels has worse quality parameters than conventional fuels, due to their higher viscosity and density. The proposal to use spiral-elliptical ducts is an innovative idea for diesel engines.

The aim of this article is to assess the possibility of using neural networks to analyse the life cycle of rolling stock in the operational phase by selecting the number of rolling stock sets and rail using the example of public transport in the Szczecin agglomeration. The research was conducted in September 2019 and June 2020. It included the number of tram and bus rolling stock sets on individual public transport lines based on data from the Central Public Transport Management System in the Szczecin agglomeration. The research, which was based on comparative analyses of individual types of rolling stock and their technical and economic data, took into account the life-cycle assessment criteria associated with the operation of vehicles in relation to the number of rolling stock sets. The use of neural networks on the example of the city of Szczecin for the purpose of life-cycle analysis, can make a significant contribution to creating a decision model for the improvement of public transport in cities with various types of public transport vehicles.