• Energy Research

A mathematical model of the vaporization process in the coil is developed, taking into account the experimental data. To investigate and visualize the evaporation procedure in the coil, a mathematical pattern of the vapor-liquid mixture motion is compiled and reproduced. In the methodology of the study of the movement of the steam-water mixture, correction coefficients are proposed for calculating the velocities of the coolant in non-standard coaxial coils. The parameters were calculated using data sensitivity analysis and data validation was performed by repeated tests; uncertainty was detected when using the instruments, as well as the total extended uncertainty, the upper and lower limit of uncertainty for each measured parameter. In addition, as part of the steam generator set, solar collectors operate in the summer mode. Using the example of the studied steam generator operating in the conditions of an oil and gas field in the subarctic climate, it is shown that it is possible to use air-type solar collectors for the ventilation system of the production room, as well as water-heating solar collectors for technical systems of hot water supply and chemical water treatment.

The problem of increasing the reliability of wind turbines exists in the development of new offshore oil and natural gas fields. Reducing emergency situations is necessary due to the autonomous operation of drilling rigs and bulk seaports in the subarctic and Arctic climate. The relevance of the topic is linked with the development of a methodology for theoretical and practical studies of gas dynamics when gas flows in a pipe, based on a mathematical model using new mathematical methods for calculation of excess speeds in case of wind gusts. Problems in the operation of offshore wind turbines arise with storm gusts of wind, which is comparable to the wave movement of the gas flow. Thus, the scientific problem of increasing the reliability of wind turbines in conditions of strong wind gusts is solved. The authors indicate a gross error in the calculations when approximating through the use of the Fourier series. The obtained results will allow us to solve one of the essential problems of modeling at this stage of its development, namely: to reduce the calculation time and the adequacy of the model built for similar installations and devices. Experimental studies of gas-dynamic flows are carried out on the example of a physical model of a wind turbine. In addition, a computer simulation of the gas-dynamic flow process was carried out. The use of new approximation schemes in processing the results of experiments and computer simulation can reduce the calculation error by 1.2 percent.

In this study, hydrogen production by solar thermal energy has been studied in terms of economics, technology and hydrogen sources. Methane was captured and subjected to solar photovoltaic steam, solar methane cracking, high-temperature water electrolysis and thermochemical cycles. The price of hydrogen production was calculated compared to other methods, and means of using and exploiting hydrogen as an energy carrier were examined in addition to verifying the industrial need for hydrogen, especially in the presence of high solar energy, which improves hydrogen production. The study was carried out in order to generate hydrogen using a solar electrolyzer based on polymeric exchange membrane technology. The study was carried out using two methods. The first was involved the direct connection of the photovoltaic system to the hydrogen analyzer, and the second was a system for a solar electrolysis hydrogen analyzer consisting of a PV array and a maximum power tracker MPPT meant to operate the system at the maximum power of the photovoltaic system at all times uses a DC converter to supply the analyzer. With the necessary current and hydrogen tank, the results showed that the first method was less effective compared to the second method due to the instability of the intensity of solar radiation during the day, and the results show that adding potassium hydroxide, for example, enhances ionization and improves hydrogen supply.

The burning of organic fuel is one of the main factors influencing the greenhouse effect on the climate of the planet. The article examines the influence of the properties of lignite and coal–water slurries on the amount of carbon dioxide molecules formed as a result of chemical reactions. The authors give an overview of the results of other researchers in recent years and give the results of their research and development in the field of burning lignite and coal–water slurries in industrial recycling plants. The authors present the results of experimental studies of the thermophysical properties of coal and a coal–water mixture. The results obtained were compared with the results of calculations using a mathematical model and the results of numerical modeling in Ansys. New methods of approximation of step functions were used for the mathematical model. These methods make it possible to reduce errors in the approximation of the functions of the thermal properties of coal. The proposed methods do not have the disadvantages of traditional decompositions of step functions into Fourier series and can be used in problems of mathematical modeling of a wide class of processes and systems. In particular, when determining the coefficient of kinematic viscosity, ash content, and humidity by the method of approximation of the obtained data, the use of new mathematical methods makes it possible to reduce the error in calculations. In addition, data on numerical modeling of hydraulic transport and combustion processes are provided, and a data validation procedure is carried out. The data convergence shown and their location in the selected band of uncertainties satisfy the requirements for verification of experimental data adopted in the European Union and in the Eurasian Union.

Transportable boiler plants are widespread in the northern regions of the Russian Federation and have a large and stable demand in various spheres of life. The equipment used and the schemes of existing boiler plants are outdated—they require replacement and modernization. Our proposed new installation includes a coil type steam boiler and ancillary equipment designed with the identified deficiencies in mind. The steam boiler coils are coaxial cylinders. The scope of the modernized transportable boiler plant is an oil field in the subarctic continental climate. The work is aimed at completing an experimental and theoretical study of the operation of a coil type steam boilers under real operating conditions. Experimental data on the operation of boiler plants are presented. The dependences of the fuel consumption of boiler plants on the temperature and pressure of the coolant are obtained. Statistical analysis is applied to the collected data. Conclusions are formulated and a promising direction is laid out for further research and improvement of coil type steam boilers. Equations are proposed for calculating the convective component of radiant-convective heat transfer in gas ducts, taking into account the design features of boiler units by introducing new correction factors. Comparison of the calculated and experimental data showed their satisfactory agreement.

The aim of this scientific research is to experimentally determine the exergy losses of a ground heat pump and further optimization for more efficient use of operating modes and improvement of individual structural elements. In addition, it is proposed to use photovoltaic panels as a backup power source for the experimental installation under study. The exergetic losses are calculated, not only for the ground heat pump itself, with R407C refrigerant. The research methodology consists in a comprehensive assessment of exergetic flows, their optimization using new methods of approximation of piecewise linear functions, and the development of prerequisites for the use of anergy as one of the components of a new type of analysis of the efficiency of low-potential energy sources. As a result of processing the experimental data, the values of Coefficient of performance (COP) 4.136, exergetic temperature for the lower heat source 0.0253 and for the upper heat source 0.155, exergetic efficiency of the installation 0.62, and total loss of specific exergy of the heat pump 24.029 kJ/kg were obtained. Controllers with the Modbus protocol were used for data collection. Matlab Simulink was used to process the experimental data. When carrying out the procedure for optimizing the operating modes and selecting several modes with minimal exergetic losses, an important role is given to mathematical methods of processing statistical data. The method of increasing the efficiency of the heat pump is shown, first of all, based on the use of photovoltaic panels as a backup power source and optimization of exergetic losses due to exergo-anergetic evaluation of operating modes. The authors present the measurement errors of the heat pump plant parameters in the form of a 3D Gaussian curve, which becomes possible only when applying new approximation methods in the processing of measurements.

The article presents an overview of modern analytical methods and experimental studies on the use of heat exchangers as part of different schemes, as well as technologies that increase the efficiency of heat exchangers using renewable energy sources. The main types of heat exchangers, and the principles of their operation, are considered. In addition, modern technologies for increasing the efficiency of heat exchangers through design are described. The practical experience of using plate heat exchangers in industry has been studied. An overview of the software development that is used in the design and optimization of heat exchange devices, as well as for the improvement of their energy efficiency, is presented. The presented mathematical models can be used for software that is applicable both to individual segments of plates of heat exchangers and heat exchangers in general, taking into account the dependence of the installation of the entire circuit on environmental parameters and location. In conclusion, recommendations are given for further research directions in the field of using heat exchangers with the inclusion of renewable energy sources. The technique of an energy technology complex, including a heat pump, a photovoltaic panel, and a desalination plant, is presented. The methodology is built around the basic design and energy balance of the complex, and it is also considered from the point of view of the exergetic balance. This allows for the use of additional components, such as a turbo expander for the implementation of the organic Rankine cycle, a wind turbine, and a solar concentrator. This scientific approach can become unified for the design and operation of an energy technology complex. In addition, an exergetic calculation method is presented for a thermal desalination plant operating as part of an energy technology complex with renewable energy sources.

Direct-flow steam boilers of the coil type are simple structures in which rather complex processes take place. To study this area, an educational laboratory stand was designed and constructed, which simulates the operation of a boiler of a similar design. In order to optimize the intensification of heat exchange processes in the device, raise its steam capacity, and improve its efficiency, the stand contains hydraulic and aerodynamic circuits for evaluating the movement of the coolant and air flows in the boiler. The proposed mathematical model gave an idea of the nature of the movement of the coolant in a curved pipe. The model takes into account the parameters of the screw channel for a more accurate result. The model can be used to predict the movement of the coolant in such coils with varying degrees of contamination. When designing a laboratory stand, the need for automated control is taken into account. The use of a controller to regulate the rotation speed of the pump motor made it possible to create a virtual desktop with which it is possible to control, regulate, and save all parameters. The results of the first test of the hydraulic system of the stand showed that the nature of movement in the object under study is turbulent, the critical value of the Reynolds number is higher than the generally accepted one due to the occurrence of additional forces in the curved pipe, and the mathematical model can be corrected by amendments for these forces.