Agro-economic substantiation of the feasibility of green manured fallow in sugar beet crop rotations of the Central Chernozem Region

The aim of the study is to find out the feasibility of including green manured fallow in specialized sugar beet crop rotations by comparing necessary assessment indicators with their values in a traditional crop rotation with black fallow against the background of unequal fertilization levels. The study was based on the analysis of experimental data from a long-term stationary experiment, laid out simultaneously in all fields and variants on typical chernozem in triplicate. The results are as follows: within the same fertilization levels, no significant differences in the yield of winter wheat (sugar beet precursor) were revealed, and the yield of sugar beet in a crop rotation with green manured fallow was stably higher (no more than 5 to 7%), an increase in yield relative to the control fertilizer variant (6 tons of manure per hectare per year) against the background of a double rate of manure in combination with mineral fertilizers amounted to 21.7 to 23.4% for wheat and 14.3 to 15.6% for beets with an increase in the productivity of crop rotations (in natural and value terms) by 1.2 times, but an increase in costs by 1.3 times caused an absolute decrease in the level of profitability by 23 to 25%. Differences in the assessment indicators for specific fertilization variants increased over time due to an unequal degree of soil fertility reproduction, and therefore in the fifth cycle of the crop rotation with black fallow turned out to be 1.1 to 1.3 times greater than in the green manured rotation

Optimal Sizing of the Evaporation Chamber in the Low-Flow Aerothermopressor for a Combustion Engine

Konovalov, D. Optimal Sizing of the Evaporation Chamber in the Low-Flow Aerothermopressor for a Combustion Engine. In: , et al. Advanced Manufacturing Processes II . InterPartner 2020. Lecture Notes in Mechanical Engineering. Springer, Cham. – P. 654–663. –https://doi.org/10.1007/978-3-030-68014-5_63The efficiency of gas turbine plants will be improved by cooling the cyclic air with an aerothermopressor. Constructive and technological factors affecting the aerothermopressor work were considered in this paper. CFD simulation and calculation of the water evaporation process in the evaporation chamber (working chamber) of the aerothermopressor was carried out. The Eulerian–Lagrangian approach was used to simulate the interaction of water droplets injected and airflow. The developed software was used in order to determine the characteristics of the aerothermopressor workflow. It is based on the methods of calculating thermogasdynamic compression and pressure losses due to the aerodynamic resistance of the two-phase flow in the aerothermopressor flow part. An empirical equation has been determined for calculating the optimal relative length of the aerothermopressor evaporation chamber depending on the initial droplet diameter at the inlet and the mass water concentration in the airflow. Analytical determination of the optimal relative length of the aerothermopressor evaporation chamber allows determining the length section of the evaporation chamber in order to obtain the maximum value of pressure increase, as a result of thermogasdynamic compression

Analysing the efficiency of thermopressor application in the charge air cooling system of combustion engine

As the analysis of the research results has shown, the use of a thermopressor makes it possible to increase the fuel and energy efficiency of a ship power plant in a wide range of the operation parameters. It can be achieved by cooling the charge air before the engine inlet receiver and by reducing the compression work of the turbocharger. A scheme with the thermopressor application in the cooling system of a low-speed main engine and in the system for utilizing the exhaust gases heat in a heat recovery boiler of one and two pressures was proposed. The use of thermopressors led to a decrease in the compressor power consumption, and therefore in the turbine required power. Therefore, it was appropriate to pass (bypass) the excess amount of gas past the turbine. Accordingly, the thermal potential of exhaust gases was increased. As a result, the temperature of gases at the inlet to the heat recovery boiler was increased by 10-15 °C, and gases heat was increased by 10-15% respectively. The obtained additional steam is advisable to use for driving the utilization turbine generator, thereby reducing the load on the ship's power plant, with a corresponding decrease in fuel consumption of diesel generators by 2-4%

Optical Diagnostics of Supercritical CO2 and CO2-Ethanol Mixture in the Widom Delta

The supercritical CO2 (scCO2) is widely used as solvent and transport media in different technologies. The technological aspects of scCO2 fluid applications strongly depend on spatial–temporal fluctuations of its thermodynamic parameters. The region of these parameters’ maximal fluctuations on the p-T (pressure-temperature) diagram is called Widom delta. It has significant practical and fundamental interest. We offer an approach that combines optical measurements and molecular dynamics simulation in a wide range of pressures and temperatures. We studied the microstructure of supercritical CO2 fluid and its binary mixture with ethanol in a wide range of temperatures and pressures using molecular dynamics (MD) simulation. MD is used to retrieve a set of optical characteristics such as Raman spectra, refractive indexes and molecular refraction and was verified by appropriate experimental measurements. We demonstrated that in the Widom delta the monotonic dependence of the optical properties on the CO2 density is violated. It is caused by the rapid increase of density fluctuations and medium-sized (20–30 molecules) cluster formation. We identified the correlation between cluster parameters and optical properties of the media; in particular, it is established that the clusters in the Widom delta acts as a seed for clustering in molecular jets. MD demonstrates that the cluster formation is stronger in the supercritical CO2-ethanol mixture, where the extended binary clusters are formed; that is, the nonlinear refractive index significantly increased. The influence of the supercritical state in the cell on the formation of supersonic cluster jets is studied using the Mie scattering technique