Method for Calculation of the Current Concentration of Alkali in the Electrolyte During the Water Electrolysis Process

The article proposes a method for calculation of the current concentration of alkali in the electrolyte, taking into account the consumption and replenishment of feed water in the electrolyzer, which allows to estimate the specific electrical conductivity of the electrolyte during electrolysis process. This is important to increase the efficiency of the water electrolysis process. The calculated change of the current concentration of alkali in the electrolyte in high-pressure electrolyzers taking into account the volume of produced hydrogen is given. With the usage of the proposed method, it is established that the current concentrations of alkali in the electrolyte during the operation of the developed high-pressure electrolyzers are in the range of optimal concentrations, where the specific electrical conductivity of the electrolyte is close to maximum and changes according to alkali concentration change

Synthesis of fused heterocycles from 2-aryl-5-(chlorosulfonyl)-1,3-oxazole-4-carboxylates and α-aminoazoles involving the Smiles rearrangement

Reaction of methyl 2-aryl-5-(chlorosulfonyl)-1,3-oxazole-4-carboxylates with 1H-pyrazol-5-amines and 1H-1,2,4-triazol-5-amines proceeds with the participation of endocyclic aminoazole nitrogen atoms to yield products containing a primary amino group. Being treated by sodium hydride these products undergo a further transformation into the tricyclic compounds. It has been shown that the cyclocondensation pathway includes the Smiles rearrangement with extrusion of SO2 followed by the elimination of MeOH. This reaction sequence is a convenient approach to the synthesis of new annulated [1,3]oxazolo[5,4-d]pyrimidine derivatives

The influence of stator-rotor interspace overlap of meridional contours on the efficiency of high-pressure steam turbine stages

The results of a systematic study of the influence of meridional contours overlap in the stator-rotor axial interspace of the impulse and reactive type stages of a high-pressure steam turbine on the flow structure and gas-dynamic efficiency of the flow part are introduced. The studied flow parts of the impulse and reactive stages are typical for high-power high-pressure steam turbines. It is shown that the stages that have no overlaps and/or have a smooth shape of meridional contours have the best gasdynamic efficiency, and the most negative effect on the flow part is caused by the presence of caverns in the stator-rotor interspace. For cases where, due to technological limitations, it is impossible to avoid the presence of caverns and overlaps with a sharp (step-wise) change in the shape of the meridional contours, it is recommended to perform overlaps with positive size of overlap values near the rotor blades

Development and Experimental Validation of Real Fluid Models for CFD Calculation of ORC and Steam Turbine Flows

The article describes an interpolation–analytical method of reconstruction of the IAPWS-95 equations of state and the modified Benedict–Webb–Rubin equations of state with 32 terms (mBWR32). The method enables us to provide the thermodynamic closure in 3D computational fluid dynamics (CFD) calculations of turbomachinery flows with real working media, such as steam and Organic Rankine Cycle (ORC) fluids. The described approach allows for the sufficient accuracy of 3D flow calculations and does not require a significant increase in computational cost over perfect gas calculations. The method is validated against experimental data from measurements and compared with computational results from the model using the Tammann equation of state. Three turbine blading systems are considered—a multi-stage configuration from a low-pressure cylinder of a large-power steam turbine and two ORC microturbines working with organic media HFE7100 and R227ea. The calculation results obtained using the described method of approximation of the IAPWS-95 and mBWR32 equations exhibit satisfactory agreement with the experimental data, considering pressures, temperatures and enthalpies in key sections, as well as turbine power and efficiency in a wide range of changing thermodynamic parameters. In contrast, the Tammann equation of state provides acceptable results only for relatively small changes of thermodynamic parameters

Application of innovative solutions to improve the efficiency of the LPC flow part of the 220 MW NPP steam turbine

The results of the gas-dynamic calculation of the low-pressure cylinder flow part of the K-220-44 type steam turbine intended for operation at nuclear power plants are presented. The ways of the flow part improvement were determined. Some of those ways include the use of innovative approaches that were not previously used in steam turbines. The design of the new flow part was carried out on the basis of a comprehensive methodology implemented in the IPMFlow software package. The methodology includes gas-dynamic calculations of various levels of complexity, as well as methods for analytical construction of the spatial shape of the blade tracts based on a limited number of parameterized values. The real thermodynamic properties of water and steam were taken into account in 3D calculations of turbulent flows. At the final step, end-to-end 3D calculations of the lowpressure cylinder that consists of 5 stages were performed. The technology of parallel computing was applied in those calculations. It is shown that due to the application of innovative solutions, a significant increase in efficiency can be achieved in the developed low-pressure cylinder

Analysis of the Efficiency of a Power Generating Plant Operating on the Basis of the Brayton Thermodynamic Cycle and Energy Recuperation

The thermal scheme of a power generating plant with a remote heat exchanger operating according to the Brayton cycle with energy recuperation is considered. It is assumed that the plant will work on non-certified (cheap) biofuel. It is shown that, in contrast to the usual Brayton cycle, in the cycle with energy recuperation, the greatest influence on the thermal efficiency is the heating temperature of the working medium and the internal efficiency of the main components of the plant, such as the compressor and the turbine. Also, in contrast to the usual Brayton cycle, a higher efficiency of the plant is achieved with smaller degrees of pressure reduction (increase) in the turbine (compressor). It was established that even at a relatively low temperature of the working medium heating (500 ºC), with high efficiency of the compressor and turbine, it is possible to achieve good characteristics of the power plant as a whole. At a temperature of up to 850 ºC, a thermal efficiency of 40% is achieved, but in this case the cost of materials and production increases. For a final conclusion about the possibility of using the proposed plant and its efficiency, it is necessary to conduct additional studies, in particular, of its main elements, such as a compressor, turbine, heat exchanger and others

Особливості функціонального забезпечення спеціальної працездатності каноїстів, які спеціалізуються на дистанції 1000 м

The aim of the study. To better understanding of the indicators of functional support for special endurance and physiological demands in canoeists at a distance of 1000 m.  Material and methods: 20 athletes (19-23 years) in canoeing from Shandong and Jiangxi provinces.  Results. According to the results of the analysis, the following typological groups of athletes-canoeists, specializing in the distance of 1000 m, with pronounced differences in the implementation of anaerobic energy supply. Typological groups of athletes had no significant differences in aerobic energy capacity (p > 0.05).  The first typological group (La max 90s <10.08 mmol·l-1, p < 0.05) is characterized by: power indicators 4.96 ± 2.35 mmol·l-1 and anaerobic energy supply capacity 6.93 ± 3.16 mmol·l-1, which were the lowest among other groups of athletes. Athletes showed significantly low performance in 10-s, 30-s and 90-s tests, and performed less work in the step test, with varying degrees of severity of fatigue compensation mechanisms.  The second typological group (La max 90s – 10.08-16.64 mmol·l-1, p < 0.05), is characterized by high power 7.4 ± 1.68 mmol·l-1 and low capacity anaerobic energy supply 13.32 ± 1.52 mmol·l-1. Athletes performed a sufficient amount of work in the step test (3-4 steps), but performance in the 90-s test was reduced, there were reduced characteristics of the ability to compensate for fatigue. The third typological group (La max 90 c-> 16.64 mmol·l-1, p <0.05) is characterized by: power indicators 8.20 ± 2.36 mmol·l-1  and anaerobic energy supply capacity 17.85 ± 1.05 mmol·l-1, which were the highest among other groups of athletes and significantly (p < 0.05) higher performance in 30-s, 90-s tests, and the level of power at which the maximum oxygen consumption in the step test is reached.  Conclusion. The results of the studies indicate differences in the level of functional support for special endurance for paddlers of uniform groups for canoeists that specialize in a distance of 1000 m. Цель исследования. Определить отличия функционального обеспечения специальной работоспособности каноистов, специализирующихся на дистанции 1000 м. Материал и методы: 20 спортсменов (19-23 года) по гребле на каноэ из провинций Шаньдун и Цзянси. Результаты. По результатам анализа выделяют следующие типологические группы спортсменов-каноэистов, специализирующихся на дистанции 1000 м, с выраженными отличиями в осуществлении анаэробного энергообеспечения. Типологические группы спортсменов не имели достоверных отличий в аэробной энергетической емкости (p > 0,05).Первая типологическая группа (La max 90-c <10,08 ммоль·л-1, p< 0,05) характеризуется: показателями мощности 4,96±2,35 ммоль·л-1 и емкости анаэробного энергообеспечения 6,93±3,16 ммоль·л-1, которые были самыми низкими из других групп спортсменов. Спортсмены показали достоверно низкие результаты в 10-c, 30-c и 90-c тестах, а также выполняли меньше работы в степ-тесте с разной степенью выраженности механизмов компенсации усталости.Вторая типологическая группа (La max 90-c – 10,08-16,64 ммоль·л-1, p<0,05), характеризующаяся высокой мощностью 7,4 ± 1,68 ммоль·л-1 и малоемкостью анаэробного энергообеспечения 13 ,32±1,52 ммоль·л-1. Спортсмены проделали достаточный объем работы в степ-тесте (3-4 шага), но показатели в тесте 90-с снизились, снизились характеристики способности компенсировать усталость.Третья типологическая группа (La max 90 c – > 16,64 ммоль·л-1, p< 0,05) характеризуется: показателями мощности 8,20 ± 2,36 ммоль·л-1 и емкостью анаэробного энергообеспечения 17,85 ± 1 ,05 ммоль·л-1, которые были самыми высокими среди других групп спортсменов, и значительно более высокими показатели в 30-с, 90-с тестах, а также уровня мощности, при котором достигается максимальное потребление кислорода в степ-тесте (p<0,05). Вывод. Результаты исследований свидетельствуют об отличиях в уровне функционального обеспечения специальной выносливости у гребцов однородных групп каноэистов, специализирующихся на дистанции 1000 м.Мета дослідження. Визначити відмінності функціонального забезпечення спеціальної працездатності каноїстів, які спеціалізуються на дистанції 1000 м. Матеріал і методи: 20 спортсменів (19-23 роки) з веслування на каное з провінцій Шаньдун і Дзянсі. Результати. За результатами аналізу виділяють наступні типологічні групи спортсменів-каноїстів, що спеціалізуються на дистанції 1000 м, із вираженими відмінностями у здійсненні анаеробного енергозабезпечення. Типологічні групи спортсменів не мали достовірних відмінностей за показниками потужності аеробного енергозабезпечення (p > 0,05). Перша типологічна група (La max 90-c <10,08 ммоль·л-1, p < 0,05) характеризується: показниками потужності 4,96 ± 2,35 ммоль·л-1 та ємності анаеробного енергозабезпечення 6,93 ± 3,16 ммоль·л-1, які були найнижчими серед інших груп спортсменів. Спортсмени показали достовірно низькі результати в 10-c, 30-c і 90-c тестах, а також виконували менше роботи в степ-тесті з різним ступенем вираженості механізмів компенсації втоми. Друга типологічна група (La max 90-c – 10,08-16,64 ммоль·л-1, p < 0,05), характеризується високою потужністю 7,4 ± 1,68 ммоль·л-1 та зниженими показниками ємності анаеробного енергозабезпечення 13,32 ± 1,52 ммоль·л-1. Спортсмени виконали достатній обсяг роботи в степ-тесті (3-4 кроки), але показники в тесті 90-с знизилися, знизилися характеристики здатності компенсувати втому. Третя типологічна група (La max 90 c – > 16,64 ммоль·л-1, p < 0,05) характеризується: показниками потужності 8,20 ± 2,36 ммоль·л-1 та ємністю анаеробного енергозабезпечення 17,85 ± 1,05 ммоль·л-1, які були найвищими серед інших груп спортсменів, та достовірно більш високими показниками потужності роботи у 30-с , 90-с  тестах, та рівнем потужності роботи, при якому досягнуто максимальне споживання кисню у степ-тесті (p <0,05). Висновок. Результати досліджень свідчать про відмінності в рівні функціонального забезпечення спеціальної витривалості у веслярів однорідних груп каноеістів, які спеціалізуються на дистанції 1000 м

Effect of 3D Shape of Pump-Turbine Runner Blade on Flow Characteristics in Turbine Mode

The effect of blade spatial profiling with the help of tangential blade lean of Francis pump-turbine runner with heads up to 200 m on the flow structure and energy characteristics was numerically investigated. A flow part model of Francis pump-turbine of the Dniester pumped storage plant was adopted as original version. Two new blade systems were designed, which differed from the original version by mutual position of cross-sections in tangential direction: with positive and negative lean, while the shape of the cross-sections themselves remained unchanged. Modeling of the viscous incompressible flow in calculation domain, which contains one channel of the guide vane and the runner, for three variants of flow parts, was performed using the IPMFlow software based on numerical integration of the Reynolds equations with an additional term containing artificial compressibility. To take into account the turbulent effects, the SST differential two-parameter turbulence model of Menter is applied. Numerical integration of the equations is carried out using an implicit quasi-monotonic Godunov scheme of second order accuracy in space and time. The study was carried out for models with runner diameter of 350 mm in a wide range of guide vane openings at reduced rotation frequencies corresponding to the minimal, design and maximal heads of the station. A comparison of pressure fields and velocity vectors in the runners, pressure graphs on runner blades, distribution of velocity components at inlet to a draft tube, and efficiency of three variants of flow parts are presented. It was concluded that calculation domain with the new RK5217M2 runner with negative tangential lean has the best characteristics. An experimental study of three runners on a hydrodynamic stand are planned