Eastern-European Journal of Enterprise Technologies

A comparative analysis of gas-cooled fast reactor using heterogeneous core configurations with three and five fuel variations

2024-02-07T20:05:41+02:00

GFR or Gas-cooled Fast Reactor is one type of fast generation-IV that uses a very high cooling temperature. Thus, it is necessary to have the right reactor core design so that the power distribution of neutrons produced reaches a safe and even limit point. The use of a uniform (homogeneous) reactor core can produce peaking power. This is very avoidable because it will cause a reactor accident. In this study, researchers tried to compare the results of the analysis for two heterogeneous reactor core designs including the configuration of 3 fuel variations and 5 fuel variations using UN-PuN fuel. This study aims to determine the k_eff value produced by both types of fuel variations during 5 years of burn-up and determine the characteristics of neutron flux, fission rate, and fission product during 15 years of burn-up. This study was started by calculating the homogeneous and heterogeneous core of 3 and 5 fuel variations with neutron transport simulation involving OpenMC. The calculation results show that the heterogeneous core configuration of 5 fuel variations for the k_eff value is more optimal than 3 fuel variations, because it has the smallest excess reactivity value. The neutron flux and fission rate characteristics for 5 fuel variations are more evenly distributed when compared to 3 fuel variations to maintain neutron lifetime and reactor life in operation. Burn-up residual plutonium material and minor actinide waste for 5 fuel variations have less mass than 3 fuel variations. The results of neutronic analysis of GFR reactors with heterogeneous reactor core designs for 5 fuel variations are better in terms of reactor criticality, neutron power distribution, and waste produced. Finally, optimization of the UN-PuN fuel volume fraction of 60 % provides the optimal k_eff value

Neutronic design of small modular longlife pressurized water reactor using thorium carbide fuel at a power level of 300–500 MWth

2023-11-15T17:37:58+02:00

This study presents the neutronic design of a small modular longlife Pressurized Water Reactor (PWR) using thorium carbide fuel with ²³³U fissile material. The target optimization for this study is a reactor designed to operate for 20 years, with excess reactivity throughout the reactor operational cycle consistently below 1.00 % dk/k. The analysis involves dividing the reactor core into three fuel regions with ²³³U enrichment levels ranging from 3 % to 8 %, with a 1 % difference for each fuel region. To achieve optimum conditions, ²³¹Pa was randomly added to the fuel. The fuel volume fraction in this design varied from 30 % to 65 %, with a 5 % incremental variation. Power level variations are also studied within the 300–500 MWth with increments of 50 MWth. Calculations were performed using the Standard Reactor Analysis Code (SRAC) program with the PIJ and CITATION modules for cell and core calculations utilizing JENDL4.0 nuclide data. Neutronic calculations indicate that the fuel with a 60 % volume fraction achieves optimum conditions at a power level of 300 MWth. The best performance was observed with a fuel volume fraction of 65 %, reaching optimum conditions across power levels ranging from 300 to 500 MWth. For the fuel with the best performance, the power density distributions for low and high power levels follow the same pattern radially and axially. The power peaking factor (PPF) for all fuel configurations approaching the optimum conditions remains below two, a safe limit for the PWR. Other neutronic safety parameters, such as the Doppler coefficient and void fraction coefficient, also stay within the safe limits for the PWR, with both values remaining negative throughout the reactor operational cycle

Enhancing savonius rotor model with additional grooves on hydrokinetic turbine performance

2024-02-22T19:35:25+02:00

Hydrokinetic turbines use different rotors for technological and economic reasons. Even though it performs poorly, vertical-axis hydrokinetic turbines use the Savonius rotor. The object of research is a Savonius rotor model with additional grooves. The study addresses the need to improve the efficiency and overall performance of Savonius rotor models in hydrokinetic turbines, which are widely used for harnessing energy from flowing water currents. The problem involves understanding how different groove configurations affect the aerodynamic behavior and energy extraction efficiency of the Savonius rotor in hydrokinetic turbine applications. The test results revealed that incorporating grooves led to notable improvements in efficiency (ɳ) and coefficient of drag (CD). Grooved blades exhibited a maximum efficiency of 30.97 % and a maximum drag coefficient of 2.71. Notably, blades with a groove width of 12.5 mm emerged as the optimal model, demonstrating an efficiency peak of 35.66 % and a drag coefficient 3.08. This indicates a substantial increase in efficiency by 4.69 % and a corresponding rise in the drag coefficient by 0.37 for grooved blades. The grooves on grooved blades increase friction, improving performance. Grooved rotor blades improve turbine performance significantly. Savonius rotor models in hydrokinetic turbines extract more energy by optimizing groove width and arrangement to maximize drag coefficient and efficiency. This research affects hydrokinetic turbine design and optimization for renewable energy generation. Engineers and designers can improve the performance and efficiency of the Savonius rotor model in hydrokinetic turbine applications by applying this study’s findings

Identifying some regularities of the aerodynamics around wind turbines with a vertical axis of rotation

2024-02-16T19:55:49+02:00

The design of wind turbines with a vertical axis of rotation is quite simple, which successfully increases the level of efficiency. Existing vane wind turbines have a shortage of currents in the form of negative torque, and installations operating on the Magnus effect have a low lifting force. In this regard, the development and research of installations operating at speeds from 3 m/s, with combined blades with increased work efficiency is an urgent topic.

The object of the study is a wind turbine consisting of a system of rotating cylinders and fixed blades operating at low air flow speeds starting from 3 m/s. Numerical studies were carried out using the Ansys Fluent program and the implemented k-ε turbulence model. A special feature of the work is the combined use of two lifting forces: a cylinder and fixed blades, which made it possible to increase the output aerodynamic parameters. Calculations were performed for incoming flow rates of 3 m/s, 9 m/s, 15 m/s and cylinder rotation speeds of 315 rpm, 550 rpm, 720 rpm. It is determined that the period of change of the moment of forces T is 0.5 m/s, which corresponds to 2 revolutions of the wind wheel per minute. It was found that the cylinder rotation frequency in the range from 315 rpm to 720 rpm does not affect the period of change in the moment of forces, but the amplitude of the moment of forces increases with decreasing rotation frequency. The dependences of the rotation speed of the wind wheel on the velocity of the incoming flow, found by the method of sliding grids and 6DOF, are also obtained. It is determined that the installation begins to make revolutions from 3 m/s, with a positive torque of forces. The field of practical application of the numerical results will be useful for further research of wind turbines with combined blades

Development of a wind turbine with two multidirectional wind wheels

2024-02-26T19:36:10+02:00

The object of research is a wind generator with counter-rotating blades. A special feature of this design is the presence of two wind wheels that rotate in opposite directions. Wind wheels are on the same axis, between them there is a certain distance, which is determined based on research data. The problem of modern wind power is the low range of operating wind speeds, weak generation at low wind speeds. The upper speed limit is 25 m/s, exceeding which leads to breakdowns of various units of the wind station, especially this affects the integrity of the blades, rupture of the wind wheel, cracking of the metal parts of the bearings and their fasteners. The wind turbine presented in the article allows to achieve an increase in the generation of electric energy by 50–70 %. This is achieved by increasing the relative rotational speed of the rotor relative to the stator. Therefore, even at low speeds, the rotor speed relative to the stator increases, which leads to an increase in power generation. The design of the device includes: two wind wheels, one transmits its rotation to the stator, the second to the rotor axis, a metal base, a current collector mechanism. For conducting the research, an experimental model and a semi-industrial installation were used. Results studies have confirmed the theoretical increase in the generation of electrical energy by this design. The peculiarity of the obtained results is connected with the determination of the distance between two wind wheels, the optimal distance between them corresponds to the maximum energy generation. A distinctive feature of the results obtained can be considered an increase in the number of blades on the second wind wheel

Development of a new fast drying determinant method using resistivity for the industry of coconut shell charcoal briquettes

2024-01-29T18:53:33+02:00

The charcoal briquette industry faces the problem of the method for determining the drying stop during its production. The combustion method as the main method is time-consuming. The test needs 3 hours to get the result. In order to find a new fast method for drying determinant, the resistivity method was proposed for rainbow coconut shell charcoal briquettes. The briquettes had a length of 3.8 cm, height of 2.2 cm, and width of 2 cm with a half-tubular top side. 50 samples of each three drying conditions (wet, half-dry, and dry) of the same drying batch were collected. These conditions were determined by a drying expert of a coconut shell charcoal briquette company. Then, the resistances were measured and the geometrical factor was applied to find their resistivities. A model of resistivity in the cross-sectional layer was also applied to find the coefficients of front-tail, base-top, and side-side directions. These coefficients became a special way to find the position of the wet part in half-dry briquettes. The results of the work show that resistivities in combination with their distribution can potentially be used for fast drying stop determinant. The wet and dry briquettes have a resistivity difference order of 10². The resistivities of the wet and dry briquettes are 450 kiloohms and 28 megaohms for every centimeter of length, respectively. The half-dry and dry briquettes have the same order of resistivities. However, the resistivity distribution of both conditions is very different. The dry briquettes have homogenous resistivities among the measurements emphasizing the drying process of the solid. It was also found that the half-dry briquette has a surface dry part until 0.55 cm depth. The center of the briquette is still wet