Refrigeration engineering and technology

11-15

Authors: A. A. Vasserman, A. S. Boychuk

Equations describing viscosity and thermal conductivity experimental data of refrigerants R125/R134a mixture are compiled. Coefficients are determined by the least square technique. Equations represent refrigerants mixture viscosity and thermal conductivity dependence from temperature, density and composition. Providing possibility to calculate mixture viscosity at temperature ranging 298…423 К at a pressure up to 6,0 MPa at subcritical and 248…345 К up to 2,8 МPа at supercritical densities. Thermal conductivity is described at temperature ranging 298…423 К up to 6,0 MPa at subcritical and 232…323 К up to 20 МPа at supercritical densities. Standard and maximum deviations of the experimental values from calculated do not exceed 3,1% and 5,3% for viscosity and 2,2% and 5,0% for thermal conductivity.

21-36

Authors: A. V. Doroshenko, V. Kh. Kirillov, A. R. Antonova, K. V. Lyudnitskij, V. V. Melekhin

The fundamental decisions of water and air evaporative coolers of direct and indirect type are developed with the lowered limit of cooling (in relation to the temperature of wet thermometer of entering to the cooler current of air). Heat-mass-transfer apparatus of film-type is executed on the basis of multichannel compositions from polymeric materials with the channels of intricate configuration. A mathematical model describing the common heat-mass-transfer processes in the evaporative coolers of indirect type (IECg and IEC-Rg) has been proposed, the comparative analysis of the developed evaporative coolers abilities has been carried out on the basis of the obtained experimental data on heat-mass-transfer processes efficiency. The initial parameters (temperature and humidity ratio) of air flow and contacting flows of gas and liquid correlation were varied in the experiment. The special attention has been spared to the features of heat-mass-transfer processes flowing at the low temperature water and air cooling.

42-48

Authors: N. V. Zhіkhareva

Using the basic principles of simulation the method for calculating of the annual consumption of cold by air-conditioning systems was developed. The initial data are: location of the building and the local weather conditions according to the long-term supervision; estimated barometric pressure; the number of working days, shifts; mass flow rates of the supply air G, outdoor air GH and recirculation Gp; coefficient of recirculation; constant or variable value of the enthalpy of recycling air hp and cooled air hoh; temperature (°C) and the enthalpy of the indoor air. On the basis of the database of the table monthly averages of temperatures tn.m (°C), outdoor air and water vapor partial pressure PH (kPa) the monthly average enthalpy hn.m. using the splines interpolation method, the total share of cold per unit of air conditioning systems air flow, the annual consumption of cold, taking into account the dimensionless factors are determined. The developed method allows to compare the alternative variants of air conditioning systems in the optimization problem.

52-60

Authors: Y. К. Коrnіenко, Y. S. Fеdchеnkо, F. А. Trіshyn

The article dwells upon the experience of implementation and application of support learning based on Moodle, which has been created and applied in the Odessa National Academy of Food Technologies since 2014. The role provided for the distance education programs is emphasized, the benefits of system based on Moodle are proved in a well-argued manner: the system is freely distributed, simple to install on any platform that supports PHP; it is spread among many institutions of higher education; it has a multilingual interface (including supported Ukrainian, English), designed to meet the advances of modern pedagogy (focus is on the interaction between the students, forum discussion); has a simple, "easy", efficient, compliant web-based interface. Besides, the system provides great possibilities to conduct assessment of knowledge. It is noted that at this stage of application of the system based on Moodle is used in the academy to support traditional education as intramural and extramural forms of study, including the organization of independent work of students. Distance Learning Center website was developed by e-mail: http://moodle.onaft.edu.ua/, requirements document, the Center operates by, were prepared and approved. Along with installing Moodle software environment it was made possible to design distance learning courses on server hosting registration. It is noted that the present system of distance learning of ONAFT contains 285 distance learning courses filled with the necessary teaching materials. In general, 190 teachers are recorded as well as more than 3,000 students of all faculties of the academy and this number is growing. The requirements that developers of distance learning courses must consider are described. Examples of already created distance learning courses, their composition and characteristics are given. Some of them are offered teachers as a model for creating your own courses. Special attention is paid to the test control of knowledge required for current control of students' knowledge. The main types of tests, such as Multiple choice, Matching, Numerical, Essay, due to their features and settings are considered. Hereafter the mechanism of creation of these types of tests is explained on examples. Considerable attention is paid to the Journal of levels, which contains test results. Quality of creation of tests is analyzed, quality parameters are provided, the means to improve this quality are offered. The latest can be done by the application of external resources in the system Moodle, for example, by applying of such online resource as LearningApps.org.

9 - 14

Authors: Y. Zasiadko, O. Pylypenko, A. Forsiuk, R. Gryshchenko

The use of cold accumulators based on the principle of ice build up on the cooled surfaces during off-peak periods and ice melting during on-peak periods is an effective method of electricity bills reduction. Within comparatively short periods of on-peak demand a noticeable amount of thermal energy related to ice melting is to be released, it becomes clear that not only sizing of ice accumulators based on balance calculations is actual, but also the determination of time periods of ice accumulation becomes critical. This work presents experimental unit for obtaining data on the ice build-up on the vertical cooled pipes and later on to continuously register data on the ice thickness diminishing at the regimes of ice melting when cooling of pipe stops. The data for ice build-up and melting for some regimes have been presented and analyzed. The data form the base for deriving semi-empirical correlations allowing to determine a time intervals necessary to generate of ice layers of a given thickness.

25 - 28

Authors: I. Butovskyi, V. Kogut, N. Zhikhareva, M. Khmelniuk

Loss control of oil products is the one of the relevant paths of saving of the fuel and energy resources play a crucial role in development of economics. Now a great many of different procedures of a choice of means of reduction of oil losses and petrol from evaporation are known. However the one part from them did not allow for value of these means and expenditures for them maintenance, another – did not allow for diversity of implementation of means of reduction of losses, third – uses outdated, now, the criterion. In the conditions of petroleum storage depots, as a rule, usage of ejector systems of trapping of light fraction are more preferential, than other hardware’s of reduction of losses. The positive effect from application of an ejector heat exchanger for preventing of losses of petroleum products are calculate.

36 - 41

Authors: V. Z. Geller, N. I. Lapardin

In this paper, solubility and low temperature miscibility of refrigerants R407C and R410A in four different commercial Polyolester (POE) lubricants, produced by the same company but with different ISO standard viscosity grade, are measured with the aim to evaluate the possible correlation of solubility and miscibility with standard viscosity of the lubricant. Vapor pressure (solubility) is measured using calibrated, constant volume cells at oil mass fractions 30, 50, 70, 80, and 90% over a temperature range from -20 to 100 °C, and pressures up to 5 MPa. The measurements of low temperature miscibility limit (lower critical solution temperature LCST) were made using high-pressure sapphire cell. LCST was directly obtained by visual observation of a «milky haze» followed by a phase separation. Miscibility data were obtained at oil mass fractions from 5 to 50% over a temperature range from -60 to 0 °C. A set of simple equations was derived to describe the experimental results. Analysis of the obtained results showed that the solubility of refrigerant/lubricant mixtures depends weakly on the viscosity grade of the oil. At the same time, the miscibility gap (LCST) differ much bigger for various refrigerant/lubricant mixtures. The lower viscosity grade of the oil, the lower LCST of the refrigerant/lubricant mixture. LCSTs for the mixtures of R407C with the lubricants with the viscosity grades 32 and 220 differ by 30-45 °С.

48 - 52

Authors: Olga V. Olshevska

Creating a computer program to calculate microchannel air condensers to reduce design time and carrying out variant calculations. Software packages for thermophysical properties of the working substance and the coolant, the correlation equation for calculating heat transfer, aerodynamics and hydrodynamics, the thermodynamic equations for the irreversible losses and their minimization in the heat exchanger were used in the process of creating. Borland Delphi 7 is used for creating software package.

12 - 22

Authors: L. I. Morosuk, S. V. Gaiduk, B. G. Grudka

Compression refrigeration machine driven by turbine (working fluid is the same as for refrigeration machine) is classified as heat-using compression refrigeration machine. The scientific development of the heat-using compression refrigeration machines associates with introducing R744 (carbon dioxide) as the working fluid. It leads to an expand in the opportunities of these machines through (a) utilization of heat with different temperature levels, (b) development of new schematics and corresponding thermodynamic cycles, (c) contribution to the energy saving, and (d) contribution to the ecological problems associated with refrigeration. A heat-using compression refrigeration machine consists of two thermodynamic cycles: direct (for generation of work) and inverse (for generation of cold). Efficiency of each cycle depends on the schematic. In this paper, the two possibilities for the direct cycle have been evaluated: simple and with heat regeneration. The energetic and exergetic methods of thermodynamic analysis have been applied. It is shown that the thermodynamic effectiveness (exergetic efficiency) depends on the combination of schematic and operation parameters within the gas heater, and the magnitude is the function of the temperature level of utilized heat. Results obtained from the exergetic analysis showed the irreversibilities within each system component and identified the components that have highest priority to be improved in order to contribute to the energy saving problem.

29 - 33

Authors: V. E. Kogut

During the last decades world industrial projects are characterized by increasing of power consumption. Considerable contribution to the power balance is deposited by manufacture of refrigeration machinery. It is the challenge for development of information technologies, revising of fuel strategies revision in favor of natural gas and other factors. Burning of petroleum hydrocarbons is associated with greenhouse gas emissions into the atmosphere, which is an environmental problem. Therefore, an intensive search for alternative compression refrigeration continues. Ejector refrigerating machines can be attributed to the best solutions. However, the wide practical application depends on many constraints - low energy efficiency (small thermal coefficients compared with absorption chillers). The author focuses on a series of relevant issues related to economic efficiency in the power industry sector. Economic efficiency of ejector heat exchangers utilization in the branch depends on the quality of heat application and investments to such heat exchangers, as well as on the operating costs. The utilization of heat exchangers is based on the qualitative usage of contact heat exchange. The classification of the ejector heat exchanger utilization in various industry branches directly related to workflow systems is given.

40 - 45

Authors: N. A. Borisov, V. V. Miroshnichenko, V. M. Arsenyev, O. G. Golubkov

Preheating fuel gas in the gas turbine can be carried out in recuperative heat exchangers installed in the lubricating system of gas-turbine engines, in which heat from the heated oil is passed to fuel gas. In such exchangers it is necessary to exclude the possibility of leakage and mixing of fluids and, in case of emergency, to provide emergency shutdown of the machine. To such heat exchangers belong gas-oil heat exchangers, which are made of bimetallic tubes with safe (signaling) channel. Secure channel provides automatic operation of the system in an emergency. The article describes a constructive solution of the gas-oil heat exchangers from bimetallic tubes with safe channel. Bimetallic tubes are used both smooth and finned, with different design of safe channel. Feasibility analysis of the use of smooth and finned bimetallic tubes in gas-oil heat exchangers was performed. It is shown that the bimetallic finned tubes allow increasing the compactness of the heat exchanger and reducing the weight and material cost of the tube bundle. The lack of methods of thermal calculation of heat exchangers with safe channel resulted in the setting of goals for further research, in particular the development of mathematical models, conduction of numerical studies and physical experiments.

62 - 65

Authors: N. V. Zhіkhareva, В. І. Реrеpека, M. G. Khmelniuk

The paper considers the method for calculating the branched air-supply systems, ventilation and air-conditioning. This paper presents a small segment of power saving tasks in the ventilation and a microscopic segment of the huge complex problems rational use of energy with the necessary reduction of harmful impact on the ecology of the system environment. The method of calculating the air supply ICU-ventilation and air conditioning is considered. The aero-dynamic calculation of fresh air system with fan was carried out according to this methodology and the "working" point was found. In a specific example, the technique evaluation of technical solutions made at the design stage in order to reduce the total cost of establishing and operating air supply system that supplies air to several pro-industrial premises and technological units. Quantitative techno-economic analysis of 3 variants of the air-supply system is given (with calculations of the payback period) for applying of a predetermined amount of air with over-pressure data in three rooms. Special recommendations on power saving during exploitation of ventilation and air conditioning systems are also given.

71 - 77

Authors: D. О. Pupkov

Development of a parabola-cylindrical solar heater designed for heating and cooking food using solar energy is presented in the study. The design consists of a reflector, as parabola-cylindrical lens and receiver as skewers for food. Reflector is made of flexible materials but also has an advantage - resistance to external influences. Simple mount design allows to collect the heater into the drawing tube, the weight of which doesn’t exceed three kilograms, making the device convenient for transportation and in use. This is a special device due to which it is possible to concentrate solar radiation in the desired point and to reach the necessary temperatures suitable for heating and cooking of foodstuffs. The heater comfortable design has been shown and calculation features of basic geometric parameters of the parabola-cylindrical solar heater are given. The comparison with existing prototypes is given.

87 - 92

Authors: S. O. Sharapov, V. M. Arsenyev

The article describes the mathematical model for calculating the geometric and power parameters of liquid-vapor ejector with a cylindrical mixing chamber and the results of numerical simulation of two-phase medium in a mixing chamber. Also the results of an experimental study of a plane-parallel liquid-vapor ejector with a cylindrical mixing chamber are submitted and compared with theoretical data. The analysis of the exergetic efficiency of the ejector with the mixing chamber is carried out.

97 - 105

Authors: S. G. Siromlia

The article discusses the features of technological preparation the company (TPC) in terms of a virtual enterprise (VE) energy machine manufacturer. The main way of the development of the TPC is complex automation on the basis of increasing the level of intelligence of the AS TPC. Integration of the system in terms of VE takes place on the basis of CALS-technologies, which provides a link for various business processes. As a basis for building such systems was selected multi-agent paradigm. To build as architecture AS TPC the most appropriate solution is to use agent-oriented architecture as a framework, divided into intelligent agents.

12-17

Authors: L. I. Morosuk

The cascade refrigeration machines are used for producing the cold at temperature level –110…-50℃. The thermodynamic cycle of the cascade refrigeration machine consists of one-stage refrigeration cycles in series. In earlier time, R12 or R22 were used as the working fluid for the high-temperature cascade as well as R13 or R14 as the working fluid for the low-temperature cascade. In modern refrigeration engineering these working fluids are forbidden. This fact requires to select another working fluids taking into account energy saving and ecological issues. R744, R717 and R290 (different combinations between high-temperature and low-temperature cascades) are the working fluids that can be used for generating the cold at temperature level -30…-60℃. They have the following advantages: the ODP values are equal to zero as well as GWP values tend to zero. In the paper, the thermodynamic analysis of the cascade refrigeration machines with R744/R744, R744/R717, R744/R290 has been conducted with R744 transcritical cycle for the high-temperature cascade. The thermodynamic analysis is based on the method of the comparison of the thermodynamic cycles proposed by R. Plank. For each cascade machine the operation parameters have been optimized to solve the “energetic problem”. For the R744/R744 cascade refrigeration machine the “transport” and the “unification” problems are also solved. The parametric study of effect of the temperature within the condenser-evaporator on effectiveness of the thermodynamic cycles has been reported. The influence of the thermodynamic properties of the working fluids to the energetic and volumetric characteristics of the cascade refrigeration machines has also been evaluated.

23-34

Authors: A. V. Doroshenko, V. A. Goncharenko, A. N. Tsapushel, Yu. I. Demianenko

The schematics of heat and mass transfer apparatus are worked out with the fluidized beds attachment "gas - liquid - solid body" for the evaporated cooling of environments (evaporative coolers of water (cooling towers CTW) and evaporative coolers of air (direct and indirect type coolers). The multifunction solar refrigeration systems and air conditioning system are worked out on the based on absorbing open-cycle with the indirect regeneration of absorbent. In the basic contours of drainage of air and cooling of environments of the solar systems heat and mass transfer apparatus are used with fluidized beds. Decisions for heat and mass transfer apparatus with the fluidized beds "gas - liquid - solid body" have been worked out in a few basic variants, in particular, with possibility of heat-exchanger placing directly in the volume of the fluidized beds. It is the evaporated air coolers of indirect type (IECg) and evaporated liquid coolers of indirect type (IECw) of cool contour of the solar systems; absorber on the air flow and desorber-regenerator of absorbent of contour of drainage of outward air of the solar systems. The cycle of experimental researches of fluidizing bed "gas - liquid - solid body" features was executed both for a variant with the free fluidized bed of attachment and in a variant with placing of heat-exchanger directly in the volume of the fluidized bed of attachment. Influence of height of stationary layer of elements, geometrical parameters of distributive grate was studied, initial parameters of current of air, entering in the heat and mass transfer apparatus. On the basis of cycle of theoretical and experimental researches practical recommendations were proposed on determination of optimal geometrical parameters of basic elements and regime parameters of heat and mass transfer apparatus operation in autonomous regime and in composition with multifunction solar absorbing systems.

42-47

Authors: A. Pavlenko, B. Usenko, H. Koshlak

The article presents the results of research of energy-resource-saving technologies of massive amorphous structures formation. This technology differs mainly the realization internal heat removal by means of local heat sink (inoculator). The peculiarities of processes of heat and mass transfer during the formation of in the melt additional active cooling centers, local heat sink to generate internal heat removal. A mathematical model of melting inoculator in melts for optimizing the process of obtaining massive amorphous structures, which allows to reduce time of experimental research and material resources to create massive amorphous structures. Mathematical modeling of processes heat and mass transfer inoculator in melts allows you to identify peculiarities of the technological process, and establish influence inoculator on the degree of amorphization melt. The results of physical experiments are compared with the results of the calculation. The results can be used to analyze the physical regularities and informed choice of technological modes of formation of massive amorphous structures in different metals and alloys. The melt metal with the cooled particles (inoculator) is characterized by supercooling condition throughout the volume of the solid ingot. Inoculators not only remove overheating and supercooling melt. The results provide an effective assessment of the intensity of heat transfer during the casting process, which makes it possible to estimate and predict the ability of alloys to the amorphization of the structure.

53-61

Authors: O. Yu. Rozina, V. B.Rogankov

The present paper concerns the generation of the sonic-capillary heat flux. Its conceptual model was presented in paper [1] and based on the experimental investigation of the sonic-capillary effect. The main statements of this model are: if the capillary was immersed into liquid, where an ultrasonic field was formed, the cavitations arise near the capillary cannel and due to the sonic-capillary force are translating into the capillary. Thus, all thermodynamic processes, connected with extension of cavities need some quality of heat should be located near the capillary cannel; the decreasing of cavities and reverse of heat to liquid are located in the capillary cannel; that’s why the heat flux is form throw the open capillary section. In this paper the results of numerical investigation of the optimal conditions for the generation of the sonic-capillary heat flux are presented. Using the original program product, the influence of the cavity parameters on the heat flux is investigated. It is shown, that an ultrasonic frequency ν determines the acceptable range of the internal diameters of the capillary, and, as consequence, the permissible range of cavities radius Rmax can be also defined. The calculations cover the range ν = (20÷100) kHc, and corresponding range of cavities radius Rmax= (0,025÷0,100) mm. Also, the results of numerical investigation for the wide range of equilibrium temperature of liquid are presented. It is shown, that due to the arising of the equilibrium temperature the kinetics of vaporization changes its parameters: the vapor in cavity remains unsaturated, thus the quality of heat, transferred throw the open end of capillary, decreases. The boundary temperature for two regimes of the evaporating is caused by the ultrasonic frequency too.

66-69

Authors: N. I. Lapardin, V. Z. Geller

The present work is dedicated to the development of the model for calculating the viscosity of the oil-refrigerant solutions based on experimental data. The results of experimental studies of density and viscosity of the mixture of compressor lubricant ISO 10 with the refrigerant R134a over a temperature range from 273 to 353 K and oil mass concentration from 0.7 to 1 are presented. Description of liquid viscosity at various temperatures and pressures based on the rough hard sphere (RHS) model, in recent years successfully in use for hydrocarbons, including pure refrigerants – derivatives of ethane and methane. Parameters of the modified RHS model were derived from experimental data for many polar liquids, including refrigerant R134a. The same model was used to describe the viscosity of binary and ternary refrigerant mixtures with the help of combination rules of molecular parameters for pure substances. We have modified the RHS model in order to apply it to the oil-refrigerant solutions. The obtained experimental viscosity data were introduced in the form of reduced viscosity, and the correlations of the reduced viscosity and density in the hard spheres model were determined with the empirical and universal for different fluids function of molar volume. Changes in the RHS model related to one of the combination rules of the molecular parameters and using an additional nonlinear term in the specified empirical polynomial function. As a result, the use of the hard spheres model for the viscosity of the oil-refrigerant mixtures was successful in spite of the task complexity (the viscosity of the lubricant is higher than the viscosity of the refrigerant by two to three orders of magnitude). The standard deviation for all compositions and temperatures was less than 6 %. Density and viscosity of the mixtures of synthetic polyolester lubricant oil ISO 10 with the refrigerant R134а have been measured over a temperature range from 273 до 353 K and a range of oil mass fraction from 0,7 to 1. The viscosity of liquid mixtures of lubricant oil-refrigerant is modeled with the modified rough hard-sphere method. The results are compared with the experimental data.

80-85

Authors: L. N. Yakub, O. S. Bodiul

The theoretical equation of state for solid methane, developed within the framework of perturbation theory, with the crystal consisting of spherical molecules as zero-order approximation, and octupole-octupole interaction of methane molecules as a perturbation, is proposed. Thermodynamic functions are computed on the sublimation line up to the triple point. The contribution of the octupole-octupole interaction to the thermodynamic properties of solid methane is estimated.

12-16

Authors: R. Gryshchenko, A. Forsiuk, Ya. Zasiadko, O. Pylypenko

The advisability of thermal energy accumulators’ utilization in food industry is presented and substanti-ated in the article. The time graphs of energy consumption for some plants along with the plots of electri-cal energy payments within a single- triple-zones tariffs as characteristic for the “Danone” diary plant in the city of Kherson have been analyzed. The results obtained have proved that the effectiveness of cold accumulators application is greatly determined not only by the available time of ice accumulation, but also by the achievable speed of the ice melting, which, eventually, determines the amount of ice which is necessary to generate during the accumulator “charge” period. The proposed considerations will be used at the developing of an ice accumulator design calculations methodology.

21-26

Authors: V. E. Kogut, I. D. Butovskyi , V. M. Bushmanov, M. G. Khmelniuk

In a paper the mode and a procedure of lifecycle calculation for systems of hydrocarbon light fractions catching on the ejector heat exchangers basis are given. The details of calculations for different systems that are necessary to take into consideration in the process of devices design. The introduced methodology of lifecycle makes it possible to evaluate the object qualitatively at on the stage of design and maintenance.

35-45

Authors: Guangming Chen, Alexander Doroshenko, Kostyantyn Shestopalov, Ivan Mladionov, Paul Koltun

Full-scale traditional metal solar collectors and solar collector specimens fabricated from poly-meric materials were investigated in the present study. A polymeric collector is 67.8% lighter than a traditional metal solar collector, and a metal solar collector with transparent plastic cov-ering is 40.3% lighter than a traditional metal solar collector. Honeycomb multichannel plates made from polycarbonate were chosen to create a polymeric solar collector. A test rig for the natural circulation of the working fluid in a solar collector was built for a comparative experi-mental investigation of various solar collectors operating at ambient conditions. It was shown experimentally that the efficiency of a polymeric collector is 8–15% lower than the efficiency of a traditional collector.

51-60

Authors: S. K. Sosnovskii, V. P. Kravchenko

The analysis of existing regulatory designing documents on chimney-type and mechanical-draft water cooling towers is carried out. It is shown the documents are out of date and to be improved. The efficiency criteria for water circulating systems (WCS), such as the mass transfer coefficient, efficiency factor of fill packing and cooling curves are lost their applied significance and no condition to solve appropriate problems. To analyze WCS with different coolers, the thermodynamic cycles in the Temperature-Time plot are introduced. The ther-modynamic efficiency of WCS, which is equal to temperature difference to cooled water temperature ratio is proved as the integral efficiency index. Diagrammatical thermodynamic cycles for WCS with a cooling tower, sprinkling basin or cooling pond are adduced and comprehensive analysis of their specific operation features is carried out. Three rules for WCS control are formulated: 1) When putting into operation and removal from service of a heat exchanging equipment, it is necessary to observe the equation of a resulting water tempera-tures drop in both heaters and coolers; 2) The cooler hydraulic load variation without its efficiency decrease, is allowed only within the operation range of its individual performance; 3) The WCS thermodynamic efficien-cy drop under production and ambient conditions is an evidence necessity to fulfill required maintenance or to repair proper equipment. On the basis of the suggested thermodynamic cycles and their analysis a comparative estimation of cooling towers, the sprinkling basin and cooling ponds is carried out. The transpiration coolers disrepairings which influence the WCS operation efficiency require their timely elimination are indicated.

66-71

Authors: O. Ostapenko, P. Stoyanov, O. Yakovleva, M. Khmelniuk

The increasing demand of energy sources for urban, household and industrial facilities requires strategies development for seeking new energy sources. In recent years an important problem is to have energy storage, energy production and energy consumption which fulfill the environment friendly expectations. A lot of attention is devoted to renewable energy sources. One of the most attracting among them is energy production form geothermal sources. At a few meters below the earth’s surface the underground maintains a constant temperature in an approximation through the year allowing to withdraw heat in winter for heating needs and to surrender heat during summer for air-conditioning purposes. Heat pump is a rapidly developing technology for heating and domestic hot water production. Using ground as a heat source, heat exchange is carried out with heat pumps compound to vertical ground heat exchanger tubes that allows the heating and cooling of the buildings utilizing a single unit installation. Heat pump unit provides a high degree of productivity with moderate electric power consumption. In this paper a theoretical performance study of a vapor compression heat pump system with various natural and synthetic refrigerants (HFCs) is presented. Operation mode of the heat pump unit was chosen according to European Standard EN14511-2:2007 and EN255-2. An influence of discharge temperature on system performance was evaluated at different boiling temperatures. The comparison of mass flow rate and coefficient of performance for considered refrigerants at constant cooling capacity and condensation temperature was performed.

78-82

Authors: А. L. Tsykalo, А. М. Коsmacheva, V. М. Smirnov

The level of influence of technogenic pollution of soil and air with heavy metals on the condition of the grass cover urban agglomeration had been studied in this paper. On the example of the Nikolayev city the ability of Taraxacum officinale Wigg plants to absorb and accumulate heavy metals from technogenically polluted environment were analyzed.

91-93

Authors: O. Olshevska, A. Selivanova

Current software tools for data analysis, their main types and properties are considered in the paper, those which can be used at the processing of data and parameters obtained as a result of scientific and industrial experiments are identified. This is the first part of the series of articles dedicated to the fundamentals of data analysis modern methods and their possible application in the power engineering industry.

100-106

Authors: G. S. Gayvoronska, B. A. Rybalov

The analysis of optical signals switching with electrical and optical control and requirements for switching systems that provide increased bandwidth telecommunication network is presented in the paper. The model and methods of implementing all-optical switching, which do not use electro-optical and optoelectronic conversion of the information signal and do not require buffering of op-tical signals in all-optical switching device are considered. The feasibility of using different modes of information transfer for switching optical signals has been estimated. The benefits and limitations of the label and position multiplexing methods are shown. A model of optical network with all-optical switching blocks of information has been described. The block mode of information transfer usage expediency for the assigned task is proved.