Issue 3 (149)
Section 1. Refrigeration engineering
V. Geller, N. Shimchuk, M. Plokhotnyuk
TRANSPORT PROPERTIES FOR REFRIGERANT MIXTURES
A set of models to predict viscosity and thermal conductivity of refrigerant mixtures is developed. A general model for viscosity and thermal conductivity use the three contributions sum form (the dilute-gas terms, the residual terms, and the liquid terms). The corresponding states model is recommended to predict the dense gas transport properties over a range of reduced density from 0 to 2. It is shown that the RHS model provides the most reliable results for the saturated-liquid and the compressed-liquid transport properties over a range of given temperatures from 0,5 to 0,95.
Key words: Refrigerant – Mixtures – Viscosity – Thermal conductivity – Model – Prediction.
D. Kuleshov, V. Mazur
FUZZY THERMOECONOMIC APPROACH TO NANOFLUID SELECTION IN VAPOR COMPRESSION REFRIGERATION CYCLE
The working fluid selection in the vapour compression refrigeration cycles has been studied as a fuzzy thermoeconomic optimization problem. Three criteria: thermodynamic (COP Coefficient Of Performance), economic (LCC Life Cycle Cost), and ecologic (GWP – Global Warming Potential) are chosen as target functions. The decision variables X as an information characteristics of desired refrigerant are presented by its critical parameters and normal boiling temperature. Local criteria are expressed via thermodynamic properties restored from information characteristics of refrigerant X, as well as life cycle costs are calculated by the standard economic relationships. GWP values are taken from the refrigerant database. Class of substances under consideration is presented by the natural refrigerant R600a embedded with nanostructured materials.
Key words: Thermoeconomics – Fuzzy Set – Refrigerant Selection – Reverse Cycle – Nanostructured materials – Nanofluids
M. Khmelniuk, D. Vazhynskyi, N. Zhikhareva
MODERN DEHUMIDIFICATION TECHNOLOGIES
Most technological processes occur in the air environment. On the one hand, the air can be the raw material; on the other hand, it defines the parameters of the environment, in which the manufacturing processes take place. The air also plays essential role in the products storage, and it is applied not only to food but also to the construction material, technology etc. Human activity also occurs in the air environment. Finally, the air is a com- mon working substance of many machines and systems. In all these cases, the air parameters play a decisive role and affect both on the quality of a received or stored products, and in some cases, on safety. They also determine the level of indoor comfort. The main task is the automated maintaining of air composition and parameters (temperature, relative humidity and velocity), favorable for business and leisure of people or required by the technological process of manufacturing companies. The main parameters that determine the air quality are the temperature and humidity. In many cases, the level of contamination plays an essential role, and besides as the contaminants may act mechanical particles and human wastes. In the systems of comfort air and technological conditioning the refrigerating processes with further drying and heating with further humidification have gained the greatest distribution. In the chambers with temperatures close to zero and positive ones, it is required, as a rule, the stable maintaining of relative air humidity at a technologically specified level. Thus, depending on the conditions, as external with respect to the chamber, so as internal, arises the necessity in air dehumidification or its humidification. For the stores with nonfood products to avoid corrosion it is necessary to maintain the low relative humidity. Production processes can occur in a variety of recommended parameters of the air environment. Modern air processing technologies allow to maintain the temperature and relative humidity at almost any level and are notable for the diversity of applied technologies.
Key words: dehumidification - sorbent – condensing method
V. Kogut, V. Minienkov, M. Khmelniuk
HEAT EXCHANGER EJECTOR APPLICATION IN PRODUCTS REFRIGERATION PROCESSING
This paper describes the use of a heatexchanger ejector device for air humidification in a refrigeration treatment camera of meat half-carcasses, and the possibility of its application for artificial snow. The system of a two-step meat moistening in the isolated compartment by treating meat with a mixture of cooled air and the fine crystal ice particles is represented in this article. The design scheme and the principle of the heat exchanger ejector is shown. The ice crystals formed at the outlet of the diffuser of the heat exchanger-ejector from the mixture of injected water droplets through the nozzle into the incoming stream of compressed cooled air. Application of a heat exchanger-ejector allows to get 100% relative humidity in the chamber. Heat exchanger ejector can be used for meat stacks snowing.
Key words: ejector, crystal ice, moisture evaporation, snow gun, freezing, moisture, snowing.
REGIMES MAP OF FLOW DURING REFRIGERANT CONDENSATION INSIDE SMOOTH HORIZONTAL TUBES: STUDIES REVIEW
The studies review on the hydrodynamic flow regimes of two-phase refrigerant flow inside smooth horizontal tubes is provided in this paper. For engineering calculations of vapor compression RU and TP (with oil separator) condensers is recommended the El Hajal-Thome-Cavallini map utilization.
Key words: Refrigerant – Condensation – Two-phase flow – Horizontal tube – Regime map – Regime flow
Section 2. Power engineering and energy saving
V.А. Аrsіry, V.О. Мakarov, Y.N. Serbova, О.V. Vishnevskaya
ANALYSIS OF WORK PARAMETERS OF THE FORCED-DRAFT MACHINES WITH DIFFERENT ANGLES SETTINGS OF IMPELLERS BLADES
In the thermal power plants and heating plants about 30% of the total cost of energy for their own needs is spent on the forced-draft system. When these systems were designed and was created the basic capacity thermal power complex, as blowers were used forced-draft machines: VD series draft fans and exhaust fans series D. Development of fan structure and aerodynamics оf the blade flow in the impeller predetermined ineffectiveness of used impeller design with forward curved blades and approved the higher performance for fans with backward curved blades. In order to save energy sources instead of draft machines series VD and D mainly were used blowers series VDN and DN. Installation of new high-efficiency blowers led to efficiency increasing, but at the same time occurred a significant reduction of the boiler thermal rating. Focusing on maximum fan efficiency, modern blowers basically became a system limiting problem, which causes draft and forced draft systems production limiting. Analysis of aerodynamic parameters of the most common draft machines VD - 15,5 and VDN - 17 showed that on the characteristics of the VD - 15,5 with rotations n = 730 rev / min in maximum efficiency ηv = 70%, the fan supplies Q ≈ 65 K. m3/hr and at maximum efficiency fan VDN- 17 efficiency ηv = 85%, the supply in the zone of maximum efficiency does not exceed Q ≈ 56 К. m3/hr. According to the comparison of the parame- ters can be seen that blowers performance with forward curved blades is up by 20% and the efficiency is 15% lower. Selection priority in the process of design and modernization of forced draft systems between two types of fans still has not been resolved. Therefore to summarize and derive concepts to solve the problem of optimal choice of a blower were made the following general conclusions: - Changing the approach to the economic value of optimal operating mode TDM providing their stable work will partially solve the nominal power derating problem of heating boilers and thermal power plants; - Indication of the aerodynamic efficiency of the systems is still efficiency blowers - fans or smoke exhausts that doesn’t fully reflect processes in the power systems, as blowers are only part of the complex processes of compression and transportation of air or flue gas; - It is advisable to analyze the epresentations of forced-draft parameters of the boilers, and the calculation of the efficiency of their work in order to have more accurate representation of the characteristics of blowers as well as individual sections of aerodynamic systems.
Key words: Boiler - Fan - Exhauster - Fan efficiency - Aerodynamic characteristics.
EFFECT OF INORGANIC MATERIALS ON THE BEHAVIOR OF SUPERCRITICAL WATER NEAR PSEUDOSPINODAL
Supercritical water is a promising working fluid in the new nuclear power plants of the 4th generation. Due to the presence of the pseudo-critical line, thermo-hydraulic as well as physical and chemical properties of supercritical water differ significantly from the pressurized hot water used in cooling loops of water reactors. The impact of small amount of inorganic substances addition to the thermal properties and hydraulics of the supercritical water utilized as working fluid for nuclear reactors cooling as well as nonnuclear supercritical water-cooling loops applications is analyzed in the paper.
Key words: equation of state, supercritical water, Widome line, nuclear power plants of 4th generation, working fluid
A.V. Doroshenko, Amina Abdessemed
SOLAR REFRIGERATION AND AIR CONDITIONING SYSTEMS ON THE BASIS OF ABSORBING CYCLE AND EVAPORATED COOLERS OF GASES AND LIQUIDS. ANALYSIS OF FUNDAMENTAL POSSIBILITIES
The concept of evaporating cooling gases on the basis of the new generation multichannel polymeric structures is developed. Natural cooling limit in such systems is the dew point of the ambient air, which significantly extends the capabilities of evaporative cooling technology in general and allows to solve a number of problems of refrigeration and air-conditioning with a significant reduction in energy costs for implementing the processes. Special attention is paid to the water vapor re-condensation during the transition to the deep evaporative cooling of media. On the basis of the authors theoretical and experimental data, preliminary analysis of such refrigerants possibilities with respect to evaporative cooling problem solving is performed.
Key words: Solar Systems – Absorption cycle –Evaporative cooler – Multichannel nozzle –Polymeric materials – Combined heat and mass transfer– Condensation of water vapor
PROSPECTS FOR IMPLEMENTATION OF INTEGRATED HEAT PUMP ENERGY SYSTEMS WITH STIRLING ENGINE FOR FARMS
A large number of agro-industrial complexes and farms in Ukraine are outside the centralized power supply and rising prices for gas and oil stimulate research of the effectiveness of integrated autonomous power supply systems based on renewable energy sources. So, implementation of power supply with integrated heat pump energy systems with Stirling engine running on biofuel is appropriate. Integrated power systems with Stirling engine utilization not only gives necessary fuel, but also different household wastes are recycled, that make treatment facilities unnecessary, as well as other measures related to the protection of the environment. Implementation of the abovementioned system will solve a number of essential problems of of security of energy supply for modern agro-industrial complexes and farms of the country.
Key words: Stirling engine Integrated power system Biofuels Efficiency Heat pump
Section 3. Refrigerating and accompanying technologies
V.G. Marchenko, A.I. Lipa, A.P. Ponomarenko
RESEARCH OF AIR IONS DISTRIBUTION IN AIR PREMISES
In the paper the experimental results of the different charge air ions distribution for working ionizer of effluence type in the office space are given. The study has been carried out using the ions generator IWS-12D1-AE (Israel) – corona type with the productivity of 5·109 ion/sec. The small air ions counter MAC-01 (Russia) was used for determination of ions concentration. The results are presented as scheme demonstrating the air ions distribution at various height and distance from the ionizer. The high local area concentration of negative air ions under the ionizer is detected. It is established that trajectory of air ions distribution from corona type ionizer IWS-12D1-AE is characterized by a parabolical shape. The concrete recommendations for the arrangement of this device are determined.
Key words: Air ions – Ionization – Indoor air quality.
Yu.О. Kozonova, D.Yu. Pruts
FUNCTIONAL DRINKS FOR ATHLETS
In this article the assortment sports drinks’ extending possibility is presented. The juice component compositions for sports drinks with different osmolality were designed. The feasibility of calcium lactate adding into the drink as a source of quick body energy renovation and as calcium deficiency’s reducer were proved.
Key words: juice drinks, drinks for athletes, energy drinks, osmolality, calcium lactate.
А.М. Kosmacheva, А.L. Tsikalo
THE PROBLEM OF SANITARY PROTECTION ZONES OPTIMIZATION
XXI century – is a century of scientific and technical progress. Scientific researches that contribute the best technical development expose many-sided possibilities for work of modern and home enterprises. Products of their production provide the necessities of population, but here, natural resources are exhausted, an environment is contaminated, the places of dumps are increased, wastes utilization is small controlled. Taking into account these and many other questions by estimation and saving environmental preservation, where we live, there is a pressing question to reorganize the structure of SPZ of the dangerous enterprises and especially vulnerable objects with the purpose of maintenance of natural environment that will contribute the best existence of living objects.
Key words: sanitary protection zone (SPZ ) – stationary and mobile sources of pollution – ammonia – chlorine – hydrogen chloride – ethylene – methane – natural filters – biogeocoenosis – flora – fauna.
Section 4. Automatic, computer and telecommunication technologies
M. O. Drozd, O. V. Drozd, I. M. Nikolenko
THE MODELS OF DIGITAL COMPONENTS CHECKABILITY IN SAFETY-RELATED SYSTEMS
The problem of the hidden faults for which fault tolerant structure of the digital components does not guarantee function safety of the safety-critical systems is considered. The structural, functional and dual-modes models of checkability for the digital components are offered. The different ways for solving the problem by these models are determined. The expedience in use of the dual-modes model which opens the way for the methods of leveling of the checkability in normal and emergency modes and also detection and elimination of the potentially hazardous points in the digital components is shown.
Key words: Safety-critical computer systems – Digital components – Hidden faults – Models of checkability – Potentially hazardous points.
G.S. Gaivoronska, A.A. Nazarenko
APPROACH TO THE CHOICE OF ROUTING PROTOCOL FOR NETWORKS OF THE FUTURE
The article presents the studies results of some aspects of networks of the future design. In this paper, most attention is paid to routing protocols. This theme was chosen because of its significant relevance and importance of networks of the future design, as one of the priority directions of further development of information and communication technologies. Internet Engineering Task Force (IETF) published a series of recommendations related to routing protocols, in particular the recommendation RFC 2328 describes the protocol OSPF v2, recommendation RFC 1771 contains the basic provisions of the protocol BGP v4. Based on this information, as well as some other data were analyzed in order to select a routing protocol for a specific task. The paper presents the most famous routing protocols. Relevant protocols are OSPF and BGP v4, supporting a large number of network nodes with high reliability and low service traffic. For non-large networks often is used RIP v2 due to the simplicity of its realization. IS-IS protocol is currently not widely used because it does not satisfy a very important requirement for modern networks, namely not support IP-routing. Protocols IGRP and EIGRP are developed by Cisco and implemented, primarily, on their equipment. It should be noted that this study is directed primarily to show that the task of choosing a routing protocol is a controversial issue and has a large dependence on various factors. These factors include: the purpose of creating a network, the number of nodes in the network, the requirements for scalability and reliability, convergence. To solve global issues appropriate to apply protocols OSPF and BGP, while BGP is a major dynamic routing protocol in the Internet. By considering a particular example of a small corporate network, for which is not necessary to use such protocols like: OSPF and BGP v4, which will be characterized by high complexity for this situation, RIP v2 is best suited. Consequently, the value of this lies in correct, competent and flexible approach to the choice of routing protocol for each case, according to the recommendations of various standards organizations.
Key words: routing protocol, theory of decision making, networks of the future.
W. G. Degtev, H. G. Abdulkareem, S. J. Marulin
AUTOMATED SYNTHESIS OF ASYMMETRIC MULTIPHASE WINDINGS
The article presents the results of the software of the automated synthesis of two-and three-phase windings with a reduced level of asymmetry. The necessity of using such a weakly asymmetric windings periodically arises on the enterprises specializing in the repair of electrical machines, so the task of such symmetrize windings design is relevant. Algorithm of synthesis of these multi-phase windings is based on balancing - achieving of practical symmetry on harmonics symmetry that ensures the correct application of the method of symmetrical components to perform a detailed harmonic analysis of the winding MDS. Implementation of this algorithm in manual mode requires multiple graphic design of vector diagrams and performing of repetitive routine calculations, therefore characterized by higher labor input. The proposed software is characterized by a user-friendly interface. Both automated and manual input of initial data, as well as their operational adjustment are provided. Visualization module of vector diagrams eliminates the need of manual graphic design, on the order reduces the time required in the process of balancing using the method of successive approximations and provides almost complete symmetry by working harmonica. On the second stage the compliance of detailed harmonic analysis and printing of the obtained results or saving in files are provided so you can use them for subsequent determination of operational properties of electric machines, in which such winding are used. Effectiveness of the developed software is illustrated by the example of symmetrize three-phase winding synthesis with demonstration of performance technology of each stage of design and comparing of its electromagnetic properties before and after balancing.
Key words: automated synthesis, multiphase windings, workers harmonic, harmonic analysis, symmetrical components method.
V.G. Tkachenco, O.V. Sinyavsky
THE CRYPTOSYSTEM CONSTRUCTION ON THE POLYGONAL CODES BASIS
The polygonal block nonlinear codes are defined in the article. The methods of certain polygonal codes constructing is considered and effective universal recursive method of codes of great length constructing on the basis of Steiner systems for cryptosystems with error correction is proposed. Cryptosystem with correction code based on this code is developed. The advantages of this cryptosystem are speed encryption and decryption, as well as the ability to change the code quickly without encryption and decryption tables changing.
Key words: Correcting Codes - Nonlinear polygonal codes – Сryptosystem – Steiner system – Affine plane – Projective plane