Issue 5 (151)
Section 1. Refrigeration engineering
G.M. Chen, A.V. Doroshenko, K.O. Shestopalov, O.Y. Khliyeva, A. Abdessemed
EVAPORATIVE COOLERS OF WATER AND AIR FOR COOLING SYSTEMS. ANALYSIS AND PERSPECTIVES
The concept of evaporative coolers of gases and fluids on the basis of monoblock multichannel polymeric structures is presented. Different schemes of indirect evaporative coolers, in which the natural cooling limit is the dew point of the ambient air, are discussed. In such systems the cooling temperature is lower than the wet bulb temperature of the ambient air. Special attention is paid to the recondensation of water vapor for deep evaporative cooling. It is shown that for the solution of the recondensation problem it is necessary to vary the ratio of the contacting air and water flows, particularly in each stage of the multistage system. Recommendations for the deep cooling process implementation in the evaporative coolers of gases and liquids are given.
Key words: evaporative cooler, multichannel packing, polymeric materials, coupled heat and mass transfer, recondensation
D.K. Kuleshov, I.N. Krasnovskiy
EXPERIMENTAL STUDY OF THE CHARACTERISTICS OF DOMESTIC REFRIGERATOR USING NANOFLYUID R600А/TiO2
Practical application of TiO2 nanoparticles doping for domestic refrigerator working with isobutene is considered. Experimental studies of energy consumption This work has demonstrated that nanoparticles can improve the performance of the refrigerator. The energy consumption test was conducted to compare the performance of the refrigerator with nano-refrigerant and pure refrigerant so as to provide the basic data for the application of the nanoparticles in the refrigeration system. It was demonstrated the nanoparticle doping reduces energy consumption of refrigerator ДХ-271 010 D 256/255/465 N/ST2,0 A+ about 4,7% at 0,05% nanoparticle concentation.
Key words: Energy consumption – Nanorefrigerants – Isobutene – TiO2 nanoparticles – Domestic refrigerator
V.Y. Labay, D.I. Harasym
THE DIAGRAM OF GRASSMANN IN EXERGETIC ANALYSIS OF AIR CONDITIONING SYSTEMS FOR CLEANROOMS
In modern technologies, which are related to energy transformation, namely in the air conditioning systems, important place are occupied by objects creation and improvement of which requires the use of innovation thermodynamics. Classic apparatus of this science is often insufficient to solve new tasks; it is necessary not only to its further development, but its combination with the elements of a systematic approach and energetic. Innovation mathematical research model of the central straight flow air conditioning system for cleanroom in order to computer’s estimation its energy effective by virtue of exergetic output-input ratio and losses of exergy depending on different factors, which have influence on its work, was used in this article. The diagram of Grassmann of exergy flows and losses for chosen air conditioning system at outdoor air temperature 42°С was defined thanks to this model. It is shown that the chosen air conditioning system has high losses of exergy in the refrigeration machine, in the pump of cold water and in the fan unit, decreasing which will give the opportunity to gain the highest exergetic output-input ratio е , and it means to gain the most advantageous economical variant of exploitation of chosen air conditioning system.
Key words: Exergy balance Air conditioning systems Cleanrooms Exergy efficiency Diagram of Grassmann
DEVELOPMENT AND IMPROVEMENT OF THE HEAT USING REFRIGERATING MACHINES
Heat-using refrigeration machines are a particular case of energy conversion systems working on the inverse thermodynamic cycles. The primary energy for such machines is thermal energy. The heat-using refrigeration machines can be divided into the three groups according to the so-called compensation process: (a) sorption (ab-sorption and ad-sorption) with thermochemical compression, (b) ejection with jet-compression, and (c) compression with mechanical compression/expansion. Development in the field of absorption refrigeration machines associates with using the water-ammonia mixture as a working fluid as well as with utilization of special schematics related to (a) rectification/dephlegmation processes and absorption process, and (b) absorption- compression machines that are most effective as low-temperature refrigeration machines and high-temperature heat pumps. Development in ejection machines goes to the direction of machines with (a) small refrigeration capacities, (b) using the natural working fluids, and (c) implementation of the renewable energy sources with different temperature levels. Development in compression heat-using refrigeration machines associates with (a) using carbon dioxide as a working fluid, (b) implementation of renewable energy sources, and (c) extended possibilities to use these machines within the tri-generation systems. Development and improvement in the field of the heat-using refrigeration machines and heat pumps are the result of long-term and successful theoretical and experimental research has been conducted in the chair “Refrigeration machines and installations” at Odessa National Academy of Food Technologies.
Key words: Heat using machines - absorption machines - ejection machines - compression heat-using machines -tri-generation – energy saving.
А. N. Radchenko
THERMOECONOMICAL METHOD OF ANALYSIS OF EFFICIENCY OF AIR COOLING AT ENGINE INTAKE BY WASTE HEAT RECOVERY COOLING MACHINES
A method of analysis heat engine (gas turbine and internal combustion engines) cyclic has been proposed. The method is based upon thermohour potential of engine intake cyclic air cooling that depends on climate conditions of performance and a type of cooling machine. The feature of the method of thermoeconomical analysis with the use of thermohour potential of cooling, that takes into account a temperature and time factors, is the possibility to determine a rational type and power installed of cooling machine, that provides achieving the maximal effect in concrete climate conditions of engine performance.
Key words: waste heat recovery cooling machine, engine, thermohour potential of air cooling.
Section 2. Power engineering and energy saving
O.S. Solomakha, E.V. Novakivskyy, O.M. Nedbailo
TEMPERATURE DISTRIBUTION IN WALLING WITH THERMAL BARRIER
We consider mitigation of heat consumption for heating by conventional energy by using lowgrade energy in the soil thermal barrier. Thermal barrier is a system of pipelines, which is located in the opaque envelope between the insulation and bearing walls. Feed warm or cold coolant in the winter or summer respectively can reduce heat loss or heat leakage everywhere envelope. The paper investigates the heat loss through the envelope with thermal barrier, temperature distribution inside the wall, depending on the ambient temperature. The influence of the thickness of the bearing wall envelope and insulation thickness on the temperature distribution in the middle of the wall Found minimum coolant temperature in the thermal barrier and the analysis of the transformation coefficient of thermal heat pump capacity building needs of the coolant at the inlet of the thermal barrier. Constructed depending the heat and heat the room, depending on the volume of heat thermal barrier. Energy savings are calculated as a percentage of heating and cooling, depending on the volume of heat (heat consumption) thermal barrier in the summer and winter periods.
Key words: thermal barrier, energy pile.
M.O. Cheplyukha, M.S. Bondarenko, D.S. Minchev, A.V. Nagirnyi
HEAT EXCHANGERS DESIGN FOR THE REGASIFICATION SYSTEM OF THE LNG TERMINAL WITH ANNUAL CAPACITY OF 5 BILLION M3
The paper is devoted to the important scientific and technical problem of development of the modern and high- efficient storage and regasification liquefied natural gas terminal. The design, calculated performance and mass-dimensional parameters of heat exchangers and pumping equipment for the regasification system of the LNG terminal with annual capacity of 5 billion m3 at the northern Black Sea coast conditions are presented. The regasification system provides evaporation and superheating of liquefied natural gas to meet the given parame- ters of evaporated gas at the inlet of the main pipeline. The composition of the system includes heat exchangers: reboilers to evaporate the liquefied gas and superheaters to get the necessary temperature of evaporated gas. The seawater is suggested as the source of heat for evaporation and superheating of the natural gas, with the pumping station is to be used for pumping the water through heat exchangers. To make a sufficient investigation the change in seawater temperature throughout the season is had to be taken into account. Peculiarities of the annual maintenance of reboilers, superheaters and pumps due to change in the seawater temperature have been shown in the paper. A shell-and-tube heat exchanger type with multiple reverse flow of LNG is suggested to use for the reboiler. The superheater is designed as the finned-tube heat exchanger with multiple cross-flow of sea- water. The set of limits was applied to the calculations among them are: the temperature drop of seawater on the heat exchanger is less then 3 °C (±1) and the maximum permissible speed of seawater in heat exchanger is 2 m/s. According to the calculations, the necessary amount of reboilers and superheaters is 10 items each type with the dimensions of reboiler about 1,25Ч1,4Ч4,1 m and superheater about 3,6Ч1,55Ч1,55 m. Seawater flow adjustment during the year, corresponding to its temperature, permits to meat ecological limits and to provide the regasification of the daily capacity of liquefied natural gas at the pressure of 4 MPa and outlet temperature greater than 2 єC as it is shown by dint of mathematical simulation. The range of seawater flow is 6700…9350 kg/s, the necessary pumping station power – 4300 kWt.
Key words: Liquefied natural gas – Regasification – Reboiler – Superheater – Seawater heat.
A.M. Yakimets, H.G. Abdulkareem
METHODS OF DETERMINING THE DIFFERENCE EMF ARBITRARY WINDINGS
The possibility of difference in EMF and traditional conditions and possibility of determining the difference calculating power at any variants education parallel branches arbitrary multiphase windings and the possibility of a difference in traditional EMF conditions taking into account the characteristics of their manifestations in synchronous machines considering additional harmonics of the magnetic field.
Key words: Parallel winding, difference emf, equalizing currents.
SCHEME DETERMINING COMPONENTS HEAT LOSS IN A MOVING LAYER OF THE MULTILAYERS WALLING
Changing attitudes to the regulatory framework of mobility layers walling requires a revision of the calculation scheme for determining losses flow, passing it. This scheme favors the development of ways to avoid them arising from the temperature difference between adjacent layers on surfaces that are automatically excluded in enclosures consisting only of closed layers. It illustrated the temperature at the boundary alignment layers in the heat input moving component, the moving stream. Description of the method should be supplemented assessment of energy in the limit Lakh moving bed that goes beyond the purpose of publication.
Key words: agile and vicious layers component flow, heat transfer, energy loss
Section 3. Refrigerating and accompanying technologies
V.L. Bondarenko, S.V. Artеmenko, E.G. Korzh
THERMOPHYSICAL PROPERTIES OF TARGET AND BY-PRODUCT IN Kr-Xe CONCENTRATES AND WORKING FLUID APPLIED IN SEPARATION LOOPS
Improvement of installation for enrichment of inert gases (krypton and xenon) requires knowledge of properties for components of air and based on it mixtures. Review of equations of state is presented in this study. The methods and calculations for phase equilibira diagram for binary mixtures Kr-Xe, Kr- O2 and Kr-N2 are performed on the base of Soave – Redlich – Kwong equation of state. Results of calculations are in agreement with experimental data. The model developed in this study is applicable for elaboration of properties of multicomponent krypton and xenon concentrates mixtures
Key words: Krypton – Xenon – Thermophysical properties of mixtures – Equation of state – Phase equilibria
V. G. Marchenko, A. I. Lipa, A. P. Ponomarenko
AIR IONS DISTRIBUTION FROM DIFFERENT IONIZERS IN AIR PREMISES
In the paper the experimental results of air ions distribution from corona charge ionizers of different designs and capacities in the office space are given. The study has been carried out using such ionizers as: effluence bipolar ionizer IWS-12D1-AE (Israel) with the productivity of 5·109 ion/sec working in «dark corona»; effluence unipolar ionizer «Super Plus-Eco» (Russia) with the productivity of 5·1010 ion/sec working in «glowing corona»; ionizer «Breeze» equipped with fan and designed using the device IWS-12D1-AE working in «dark corona». The small air ions counter MAC-01 (Russia) was used for determination of ions concentration. The results are presented as schemes demonstrating the air ions distribution at various height and distance from the ionizer to the breathing space of the person. The high local area concentration of negative air ions under the ionizer is detected. It is established that trajectories of air ions distribution from tested ionizers is characterized by a parabolical shape. The concrete recommendations for the arrangement of these devices are determined.
Key words: Air ions – Ionization – Indoor air quality.
J. Kozonova, D. Prutz
SPORT DRINKS WITH DIFFERENT OSMOLALITY
In this article the assortment sport drinks’ extending possibility is represented. The juice component compositions for sport drinks with different osmolality were designed. The feasibility of adding into the drink calcium lactate 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.
Section 4. Automatic, computer and telecommunication technologies
М. S. Solodovnik, А. М. Aslanov
ANALYSIS OF FUZZY DECISION SUPPORT SYSTEM FOR COMPUTER SYSTEMS ENGINEER DESIGNER
Article, the authors considered, analyzes a very relevant topic. Indeed, fuzzy systems are being in- troduced today in virtually all spheres of human activity. With DSS, computer systems engineer designer can determine the quantitative characteristics of the network parameters (for example, the delay time). The authors have created a knowledge base. With this knowledge base, and Matlab (FuzzyTech) programming environment, the authors calculated the time delay of the video on a computer network, taking into account important parameters such as packet rate, channel capacity, channel length and the number of nodes in the network. The corresponding graphs and drawings were shown, as well as the appropriate conclusions regarding the application of this method in practice were drawn.
Key words: decision support system, engineer designer, time delay, bandwidth, knowledge base, the length of the communication channel, packet rate, the expert system.