Issue 6 (152)
Section 1. Refrigeration engineering
P.V. Borzenkov, V.P. Zhelezny
THE NANOPARTICLES EFFECT ON THE LIQUID-LIQUID PHASE EQUILIBRIUM PARAMETERS. PART 1.
Nanofluids (NF), i.e. fluids embedded with nanostructured materials, exhibit greatly enhanced thermal properties. The exploitation of NF phenomena is a tool for creation of new class of effi-cient working and heat transfer media for wide range of technological application. It is obvious that nanoparticles have an influence on thermophysical properties. The influence depends on nature of the NF, its size and concentrations and thermodynamical parameters. For today, the viscosity and heat conductivity are most investigated properties of the NF. On the other hand, the influence of the nanoparticles on the surface tension, phase equilibrium liquid-liquid (LLE), vapor-liquid (VLE), solid-vapor (SVE) has not been adequately investigated.The results ofstudies of the effectof nanoparticles(TiO2andAl2O3witha mass concentration of0.01% and0.017%in the sample, respectively) onthe parameters ofthe phase equilibriumliquid-liquidsystemsnitrobenzene-heptane andH2O-phenol-isopropanol are given in the article. The experimental setup for the study of the coexistence curves in a wide temperature range was created as part of the study. The experimental setup, methodology of the experiment are outlined. The tables of the experimental data are presented. Conclusion about the effect of nanoparticles on the parameters of the coexistence curve are made according to the results of studies. The presence of small amounts of TiO2 nanoparticle sin heptane and Al2O3in isopropanol reduced the separation temperature. This effect should be considered as positive. Because it will contribute to a better entrainment of compressor oil impurities from the evaporator.The composition of the solution in the upper critical point of the coexistence curve practically are unchanged.
Key words: Layering curve – Nanoparticle – Concentration – Nanofluid – Experiment
EQUATIONS FOR REFRIGERANTS R32 AND R125 THERMAL CONDUCTIVITY CALCULATION
Equations for thermal conductivity of alternative refrigerants R32and R125 for variable temperature and density were worked out. The reliable equation of state was used for each refrigerant. Coefficients of the equations were determined by least-square method on the experimental data. The equations describe the thermal conductivity in the temperature range from 223 to 466 K at pressure up to 50 MPa for R32and from 228 to 513 K at pressure up to 53 MPa for R125. The accuracy of the equations is acceptable for engineering calculations.
Key words: Refrigerants – R32 – R125 – Thermal conductivity – Equations.
V.A. Naer, A.V. Rozhentsev, Hasan Vesam Anvar Ali
CRYOSURGICAL APPARATUSES – COLD ACCUMULATORS
Cryosurgical apparatuses exploiting a phase transition “liquid – vapour” of the working agent (nitrogen apparatus) and phase transition “liquid – solid state” of the working agent (ethanol apparatus) are considered in the paper. Schematics and design of the apparatuses with the heat load input directly to the operating nozzle/cap, through a special cryoprobe which was manufac-tured as a solid copper rode and in the form of heat pipe. The main distinctions of those apparatus imply that in the nitrogen apparatus the working agent (N2) has to be replaced after every surgery unlike the ethanol apparatus where total amount of the working agent (ethanol) is steady and has to be just refreezed after surgery. Advantages and shortcomings of the considered designs are discussed. The prospects for the reported designs of the cryosurgical apparatus have been pointed out.
Key words: Cryosurgery – Cryoprobe – Heat pipe – Nitrogen – Ethanol – Phase transition.
А.N. Radchenko, A.V. Grich
ТНЕ COOLING OF TRIGENERATION SYSTEM GAS ENGINE ROOM INTAKE AIR
Based on the analysis of the cooling performance of trigeneration system gas engine room intake air the rational way of cooling by supplying a cooled intake air to the inlet of turbochargers and to the alternators and cylinder heads of the cogeneration gas modes and ventilation of the main volume of engine room was developed.
Key words: trigeneration system – engine room – reciprocating gas engine – cooling – ventilation.
Section 2. Power engineering and energy saving
D. Vybornov, S. Monakh
THE RESULTS OF EXPERIMENTAL AND ANALYTICAL STUDY OF HEAT PUMP SYSTEM OPERATION EFFICIENCY
The dependencies outlined the heat pump system operation efficiency obtained experimentally by experimental design are presented in the paper. Because the factors interaction effects in the tested object were negligible, the ¼ full factorial experiment replica was applied.
Key words: heat pump installation – refrigerant – the regression equation – exergic efficiency – the conversion coefficient of heat – efficiency.
A.V. Doroshenko, K.V. Lyudnitskij
SOLAR ABSORBING SYSTEMS OF HEATING AND COOLING OF ENVIRONMENTS ON BASIS OF MULTI-STAGE HEAT-MASS-TRANSFER APPARATUS
The worked out schematics for the alternative refrigeration systems and air-conditioning systems, based on the utilization of absorption cycle and solar energy for the regeneration (renewals) of absorbent solution were presented in the paper. Factorable principle of construc-tion of all heat-mass-transfer apparatuses is used with varying of both temperature level and growth of absorbent concentration on the cascade stages. Heat-mass-transfer apparatuses are compatible and executed on the basis of multi-stage monoblock compositions from polymeric materials. The preliminary analysis of possibilities of the solar systems was executed as it applied to the tasks of environments cooling and air-conditioning.
Key words: solar systems – air drainage – environments cooling v air-conditioning v heat-mass-transfer apparatuses – absorption – desorption – evaporated cooling
N.A.Prusenkov, S.N. Bаbyuk
SUPERPOSITIONING OF MOVABLE STREAM ON СОNSTITUENTS: А) CROSSING OUTWARD SURFACES AND B) WITH MOVABLE ENVIRONMENT
The above arguments that illustrate the moving layers potential using perspectives and lack of regulations in the theoretical basis and methodics of calculation methods for energy losses reducing due to retrofitting and exploitation of fences with moving layers, should encourage the organization, research and implementation of their results to reduce losses in the multilayer walling.
Key words: the reserved layer, movable layer, heat transfer temperature of surface, moving of en-ergy, loss of energy a stream, cooperation, environment, constituents.
Section 3. Refrigerating and accompanying technologies
NEURAL NETWORK PREDICTION OF REFRIGERANTS PROPERTIES: REVIEW
The review of recent papers related to modeling of refrigerant properties using artificial neural networks as an alternative to conventional thermodynamic approach for modeling prediction of thermodynamic properties of refrigerants has been given in the paper. The study also discusses efficiency, adequacy and limitation of this approach.
Key words: Artificial neural network – Properties of refrigerant – Phase equilibria
N.V . Zhikhareva
MATHEMATICAL MODEL OF PELLICLE HUMECTANT FOR FRUIT AND VEGETABLES STORES
The mathematical model of pellicle humectants is worked out for fruit and vegetables stores. The adequacy of this model has been tested and calculation of pellicle humectants for fruit and vegetables store has been conducted. This humectants was realized on typical fruit and vegetables store.
Key words: pellicle humectants, fruit and vegetables store, heat and mass exchange рrocesses, mathematical model, cooling system
M. Kolosov, V. Emelianov
One-dimensional transient thermal model of the lengthy HTS conductor using thermoresistive ef-fect to measure the level of cryogenic liquid was created. Resulting model made it possible to de-termine the distribution of pacetures along the length of the HTS conductor and other characteristics. The comparing-of calculated and experimental data obtained at an atmospheric dewar with liquid nitrogen was carried out.
Key words: HTS conductor - nonstationary thermal conductivity - level gauge.
Section 4. Automatic, computer and telecommunication technologies
G.S. Gayvoronska, Y.S. Kazak
RESEARCH MODEL OF CLOUD TECHNOLOGIES DEVELOPMENT DESIGN
Existing forecasting methods of cloud technologies development are researched in the paper. Nowadays cloud computing topic became the most popular in the IT-sphere. Cloud computing is a new field of research; its evolution prospects are still hazy. It is necessary to have forecasting method of cloud computing technology development in time (both on short-term, and for the long term period) in order to assess prospects of its usage. Process of forecasting is rather actual now as forecasting is widely used in industry and economics. It is possible to make preliminary conclusions concerning development of different processes, phenomena, reactions and operations for the usage of extrapolation for available tendencies identification. Design of forecasting method of cloud technologies development process includes the development of task research model. Time series served as basis of graphical representation the further development technology is the result of model application. Designed model is tested under the research the information technologies development, in general. After that necessary changes allowed the application modified model for investigation the cloud and hazy technologies were inserted. During the subsequent researches by means of the developed model it is planned to define features of cloud technologies usage for Internet of Things concept’s introduction in Ukraine. This direction of researches is very important and urgent at creation of information society in our country.
Key words: Forecasting – Cloud Technologies – Information-communication technologies – Net-work access – Internet of Things.
The subject of the research, some results of which are presented in this paper, is focused on the development of modern telecommunication networks in Ukraine and allows solving the problems at the networks design and organization of access to infocommunication services. The chosen theme is closely related with the main direc-tions of the world telecommunications development, which are defined in the main existing regulations and laws. A characteristic feature of computer information systems’ progress, which are actual in Ukraine, is an absolute priority of expert systems’ development. Questions of the expert systems’ usage at the design and development of telecommunications networks in the modern world are considered in the paper. The problem of expert system’s development, which allows enhancing of the design and operation of telecommunication and access networks, is being solved within the given work. Statement of the problem is limited by the development of the algorithm for the expert system’s development and analysis of the theoretical aspects of the knowledge based intelligent system’s design. Done work formulates the qualimetry problems and helps to understand how to build an expert system for the access networks’ rational development. Expert system, allowing to choose proper access technology, is developed as an example. Particularly DSL technologies are considered at the first stage. The last mile is quite specific network’s segment. It should have enough bandwidth while providing great transmission range without regenerators. This expert system will de-termine the best option of DSL technology on the basis of the desired properties. The system is developed with the usage of Expek Pro software (version 1.5+) for Windows. The article consists of five sections - introduction, problem statement, the main part - the necessity of an expert system’s development for the telecommunication networks’ design, an example of the developed expert system and conclusions, as well as includes bibliography, used at the work writing.
Key words: Access network – Parameters of access networks – Expert system – Design of telecommunication networks