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This research aim is to develop a method for modeling the conditions for the critical hydraulic impacts emergence on thermal and nuclear power plants’ pipeline systems pressure pumps departing from the general provisions of the heat and hydrodynamic instability theory. On the developed method basis, the conditions giving rise to the reliability-critical hydraulic impacts emergence on pumps for the thermal and nuclear power plants’ typical pipeline system have been determined. With the flow characteristic minimum allowable (critical) sensitivity, the flow velocity fluctuations amplitude reaches critical values at which the pumps working elements’ failure occurs. The critical hydraulic impacts emergence corresponds to the transition of the vibrational heat-hydrodynamic instability into an aperiodic one. As research revealed, a highly promising approach as to the preventing the critical hydraulic impacts related to the foreground use of pumps having the most sensitive consumption (at supply network) performance (while other technical characteristics corresponding to that parameter). The research novelty refers to the suggested method elaborated by the authors’ team, which, in contrast to traditional approaches, is efficient in determining the pump hydraulic impact occurrence conditions when the vibrational heat-hydrodynamic instability transition to the aperiodic instability.

В работе представлены результаты энергоаудита, проведенного на семи объектах в 2013 году сотрудниками Института Энергетики АНМ, которые являются авторизированными в электрои теплоэнергетике. Четыре энергоаудита относятся к анализу эффективности энергопотребления в зданиях, три к энергообследованию систем уличного и внешнего освещения. Для каждой организации были выявлены основные проблемы, которые ведут к повышенным потреблениям энергии и были предложены различные меры способствующие снижению энергозатрат, а также снижению выбросов СО2. Расшифровано понятие энергоаудита, дана характеристика мероприятиям, выполняемым в процессе его проведения. Описано использованное для проведения работ оборудование. Дан анализ характерным проблемам по каждому объекту, а также возможные способы их решения. Определены необходимые инвестиции для внедрения предлагаемых мер по энергоэффективности. Оценен экономический эффект и срок окупаемости как для каждого объекта, так и по всем объектам в целом.

În lucrare se analizează structurile existente de celulele fotovoltaice, parametrii acestora, ţinând cont de durata de viaţă, randament şi cost. S-a stabilit, că randamentul acestora variază de la unităţi de procent până la câteva zeci de procent. Cele cu randament înalt peste (20%) au un cost de 5-10 ori mai mare ca cele cu randament de până la 15%. Pe piaţa Republicii Moldova se comercializează numai panouri cu celule fotovoltaice de randament până la 15%. Durata de viaţă este cuprinsă între 20 şi 30 de ani, iar după 15 ani de viaţă randamentul celulelor solare se reduce cu 10%. În plus, acesta mai depinde şi de temperatura mediului şi se reduce cu aproximativ 0,3% la fiecare grad, parametrii tehnici fiind daţi pentru temperatura de 25oC. Totodată, se menţionează că în timpul apropiat se va pune accentul pe celulele solare organice care în prezent au un randament la nivel de 5-7%. Pentru a crea o nouă generaţie de celule solare cea mai promiţătoare este considerată construcţia, în care stratul de siliciu nanocristalin este încorporat între straturi subţiri de siliciu amorf. Aceasta oferă o eficienţă foarte mare a bateriei, în plus, ea elimină necesitatea de substraturi masive din monocristale de siliciu, consumul acestui material scump se reduce.

The work is devoted to the study of heat transfer in channels with a longitudinal pressure gradient. The aim of the work is to develop methods for increasing the heat transfer intensity in channels with a longitudinal pressure gradient. The goal was achieved by developing the original design of the surface intensifier, made in the form of a horseshoe-shaped dimples, as well as by conducting heat transfer studies in the channel with a longitudinal pressure gradient and dimples of various geometries and locations. It was found that a numerical solution using the k-epsilon turbulence model shows not sufficiently stable results, including the values of local heat transfer coefficients can exceed 2 ... 2.5 times their actual values for a single dimple. Moreover, the use of the k-w-sst turbulence model shows more stable results. The most significant results obtained in the work are as follows: it was revealed that the use of holes, their geometry and location have a significant effect on the heat transfer intensity in a channel with a longitudinal pressure gradient; the design of the original horseshoe-shaped dimples has been developed, the use of which allows to intensify heat transfer by 13 ... 47% depending on the Reynolds number when they are arranged in three rows in the corridor order compared to staggered hemispherical dimples; when comparing the efficiency of using the developed dimples with hemispherical holes installed in three rows in the corridor order, the heat transfer increased by 21 ... 51% when the Reynolds number changed from 3000 to 15000.

A significant number of domestic and industrial boilers are in operation in Ukraine. Nitrogen oxides are the most dangerous among all combustion products that pollute the atmosphere, therefore, one should take some measures for decreasing the formation of nitrogen oxides during combustion. The studies were carried out at the boilers of low power (100 kW) with a tubular radiator and an open end. The studies in the furnaces of industrial steam boilers having a tubular radiator with a closed end have not been done. The numerical study results of the gaseous fuel combustion processes in the furnace of a DE-10/14 steam water-tube boiler are presented. The fuel-air mixture is formed by premixing the 15% part of the air with a primary burner twist factor n=2.4 and a secondary burner twist factor n=1.6, and an air excess factor αв=10. As a result of the studies, the temperature and velocity distributions of gases in the combustion chamber, the density of heat flows on the screen tubular surfaces, and the concentrations of the combustion components were determined. Flue gas recirculation in the volume of 80-100% is provided, and the reversible movement of combustion products towards the combustion front provides a reduction in the concentration of nitrogen oxides up to 123-125 mg/m3 at the furnace outlet. Disadvantages are the following: the formation of stagnant zones near the end of the secondary radiator. The optimum diameter of the tubular radiator equals to two burners diameters and tubular radiator is located at a distance of one meter from the burner cutoff.

The purpose of this work is the theoretical substantiation and development of a practical method for calculating the exchange fund of electrical equipment of an industrial enterprise. The purpose is achieved through the use of separate methods of queuing theory if the flow of applications for repairs and restoration are the simplest. It is confirmed by the results of statistical studies. Therefore, for the mathematical description of the repair problem the authors use the scheme [Mm; Ms; n], which corresponds to the process of death and reproduction. As a criterion for optimizing the exchange fund of electrical equipment it is proposed to use the zero probability waiting for the replacement of a faulty electrical component with a working from the exchange fund. For the case of the simplest flow of applications for service, the authors suggest to use the Peck and Hazelwood tables, which significantly simplify the calculation of the exchange fund for known failure rates and electrical equipment recoveries. For practical use of the proposed method, the authors have developed convenient forms for presenting initial data for calculating the exchange fund, and it is proposed to present the results of calculations in the form of several options for the optimal number of electrical equipment in the exchange fund depending on the accepted level of zero expectation probability, the number of elements from the exchange fund and their recovery time. The proposed method will optimize the exchange fund of electrical equipment and reduce the cost of its formation.

The presence of higher current harmonics has a negative impact on the efficiency and reliability of the elements of network. Higher current harmonics can lead to significant increases of resistance, voltage drop and active losses in busbar, also to decreasing network power factor. Existing engineering techniques can’t provide a reliable calculation of the parameters of busbars at higher current harmonics influences. Therefore, the aim of the work is to develop a new approach of parameters determination and the voltage drop estimation in busbar at higher current harmonics influence. Mathematical model of electromagnetic processes in busbar, which takes into account their design features, non-linearity of magnetic and electrophysical properties, proximity effects, surface and external surface effects, was developed and proposed. This model will allow to determinate the components of active and reactive resistances of busbar, voltage drops for each eigenvalue of the amplitude and frequency of current harmonics. Based on field simulation results was obtained the functional dependence in bicubic polynomial form. For effective spectra and amplitudes of higher harmonics, at selecting the corresponding polynomial coefficients, it will allow to determinate the components and the resulting values of voltage drops for an individual busbar’s design without spending time on field simulation. Based on the proposed approach, a method will be developed for the busbar's parameters identification and voltage drop estimation. This will allow effectively define the network configuration, installed capacity of compensating devices, which will provide the reliability of electrical collectors with the declared technical data and etc.