Issue 6 (146)
Section 1. Refrigeration engineering
А. V. Doroshenko, К. А. Rzhesik, М. V. Gordienko
NEW FEATURES OF EVAPORATIVE COOLERS FOR POWER AND REFRIGERATION SYSTEMS
The concept of an evaporating cooling gases and fluids on the basis of the new generation multichannel polymeric structures. 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 you 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 condensation of water vapor when deep evaporative cooling media. Is made on the basis of theoretical and experimental data, the authors, preliminary analysis of the possibilities of such refrigerants with respect to evaporative cooling water in cooling towers and chillers.
Keywords: Evaporative cooler – Polymeric materials – Combined heat and mass transfer – Condensation of water vapor.
A. Gorin, M. Demin, A. Kudrin
USING METHOD ABOUT DIAGNOSING OF LEAKAGE OF THE REFRIGERATING AGENT FROM REFRIGERATING SYSTEM OF THE HOUSEHOLD REFRIGERATOR
In work demonstrated theoretical bases and results of experiment about distribution of temperature on a surface of the evaporator and in volume of the freezing chamber of the household DH-239 refrigerator (HR) working at isobutane are presented. The action principle, the location of the sensor and settings of the device of automatic equipment signaling about leakage of a coolant from the HR refrigerating system, working are proved at various states of a temperature regulator, in the range of ambient temperature from 16 up to 43 degrees сelsius.
Keywords: Household refrigerator –Evaporator – Izobutan – Filling dose – Ambient temperature.
V.А. Nayer, А.V. Rozhentsev, Hаsаn Vеsаm Anvar Аli
WORKING SUBSTANCES WITH THE «LIQUID-SOLID BODY-LIQUID» PHASE TRANSITION FOR CRYOSURGICAL APPARATUSES
An autonomous cryosurgical apparatus that uses latent heat of melting of a prefrozen working substance as a source of cold is considered in the present article. The process of the substance freezing is taking place in a cold accumulator that represents a hermetically sealed container. In the course of the phase transitions “liquid - solid body – liquid” amount of the working substance is unchangeable and therefore the cold accumulator can be used repeatedly. A separate refrigerating machine could be used to freeze the working substance in the accumulator and this makes the peculiarity of the apparatus. A Joule-Thomson refrigerating machine of a simple design with a phase separator and operating by use of azeotropic mixture of refrigerants can advisably be used for this purpose. Thermophysical properties of more than 20 substances candidates with melting temperatures within the range of (-100…-150)°С that is acceptable to the apparatus operating conditions are presented in the article. Ethanol seems to be the most appropriate agent, which is in a liquid state under the normal conditions; has the melting/freezing temperature of -114°С and the latent heat of phase transition “solid body – liquid” of 104.4 kJ/kg.
Keywords: Cryosurgical apparatus – Working substance – Phase transition – Melting temperature –Ethanol – Mixture of refrigerants.
A. S. Boychuk
EQUATIONS FOR CALCULATION REFRIGERANTS R32, R125 и R134a VISCOSITY AND THERMAL CONDUCTIVITY
Equations for viscosity and thermal conductivity of alternative refrigerants R32, R125 and R134a are made by temperature and pressure variables. Coefficients are determined from experimental and calculated data by means of least square method. Equations describe gas viscosity in temperature range from 298 to 423 K at pressure up to 5,5 MPa for R32, up to 3,7 MPa for R125 and up to 3,9 MPa for R134a. Gas thermal conductivity is described in temperature range from 283 to 434 K at pressure up to 5,0 MPa for R32, from 264 to 354 K at pressure up to 2,8 MPa for R125 and from 293 to 515 K at pressure up to 2,8 MPa for R134a. The precision of composed equations is quite acceptable for the engineering calculations.
Keywords: Refrigerants – R32 – R125 – R134a – Gas – Viscosity – Thermal conductivity – Equations.
Section 2. Power engineering and energy saving
V. P. Buzovskiy, M. M. Kologrivov
RESULTS OF HYDRODYNAMIC PICTURE MATHEMATICAL SIMULATION IN THE EJECTION APPARATUS
The paper presents the design of gas-liquid flow characteristics of the flambeau which is formed in a parallel-flow direct contact heat exchanger at horizontal liquid atomizing. All known earlier computational models were developed for vertical ejection apparatus. Presented model of the flambeau hydrodynamics can be used in the heat and mass transfer processes during condensation of oil products vapor from the vapor-gas mixtures on the drops of atomized liquid simulation. An algorithm for numerical solution of differential equations systems that constitute the model is proposed.
Keywords: Direct contact heat exchanger; Hydrodynamics of gas-liquid flambeau; Mathematical simulation.
A. Dimitrov, O. Yakovleva, M. Khmelniuk
IMPROVING OF THE TECHNOLOGICAL OBJECTS ENERGY EFFICIENCY
In this paper the overview and analysis of existing methods and ways of improving the technological plants’ energy efficiency in time of their reconstruction or design process are conducted. The different types of industrial plants are discussed. The ways of industry are chemical, petrochemical, mineral fertilization, metallurgy of black and colored metals, cellulose and wood-chemical, construction materials, food, chemical and pharmaceutical, agricultural products processing and different biotechnological processes and heat and power engineering as well.
Keywords: Energy consumption – Thermodynamic analysis – Exergy – Pinch-analysis – Com-pound curve – Technological objects – System analysis – System emergentness – System interactness.
V. Kogut, I. Butovskyi, N. Nosenko
DESIGNING OF THERMO EJECTOR CONDENSER
The article dealt about inkjet devices, heat exchangers in the oil processing industry. The authors focus on an entirely new design inkjet device, heat exchanger with contact heat exchangers - thermal condenser ejector. The analysis of the thermal condenser are represented the phenomenological model of the flow behavior in the unit. Also in this article presents a superficial calculation thermo ejector condenser.
Keywords: contact heat exchanger – thermal condenser ejector – condensation of hydrocarbons.
B. V. Коsоy, Y. Utaka, М. І. Slobodenyuk
TECHNOLOGY OF MICROCHANNEL EVAPORATIVE THERMOREGULATION
This study is devoted to experimental and theoretical analysis of application of flow boiling heat transfer phenomenon for thermal control issues. The authors present an experimental research of heat transfer and critical heat flux (CHF) for subcooled flow boiling of ethanol in microchannel heat exchanger consisting of 28 rectangular channels with hydraulic diameter of 0.5 mm. Investigation was completed for ethanol velocities range of 0.5-1 m/s and inlet temperatures 48, 58 and 68o C. The onset of the critical heat flux is directly related to the hydraulic instabilities which result in the emission of vapor into the inlet manifold. Subcooling of the fluid significantly effects the value of CHF, especially at high flow rates.
Key words: Microchannel – Boiling – Heat Transfer – Wetting – CHF.
Section 3. Refrigerating and accompanying technologies
V. V. Klymenko, A. V. Skrypnyk, M. V. Lychuk
IMPROVING THE EFFICIENCY OF NATURAL COLD USAGE IN FRUIT AND VEGETABLE STOREHOUSES
The article deals with the classification of fruits and vegetables storehouses on the basic characteristics that determine the conditions of natural cold use in them. The schematic solution of the storehouse with outside air active ventilation system, equipped with dynamic thermal insulation and natural cold gas hydrate battery is proposed. The usage of natural cold gas hydrate battery for heat flows localization allows to reduce energy consumption for cooling of products in the system of active aeration and to increase an exergy efficiency in 1,2...1, 8 times.
Keywords: fruit and vegetable storehouse - Dynamic heat insulation – Battery of natural cold - Energy consumption – Gas Hydrates - External heat gains - Coefficient of external heat inflows - Share of losses from products shrinkage - Exergy efficiency.
S. M. Kontush, S. A. Shchekatolina, S. M. Dykhanov
APPLICATION OF PARTICLE LASER COUNTER FOR AIR PURITY MEASURING
The capabilities of Novatek-Electro LTD laser counter under the conditions of expeditious monitoring (7 secs. for measuring of air contamination with aerosol fraction PM 2.5) have been studied in the paper. Possibility of determination of aerosol mass concentration using this counter is also shown and calibrating for different dusts with the coefficients of refraction from 1.17 by comparing to the testimonies of AFA VP filter for the same dusts is carried out. It is found that 1.65 calibration coefficient enables to define the mass concentration of dust in the air by a laser counter with the error of less than 20%.
Keywords: Laser counter; Sizes of aerosol particles; Number concentration; Mass concentration.
Section 4. Automatic, computer and telecommunication technologies
I. V. Grishchenko
INFOCOMMUNICATION NETWORKS SURVIVABILITY INCREASING METHOD
The article provides the method of optimal reservation hub equipment to ensure the required level parameter «betweenness». Solution of the problem of optimal reservation enables you to define the structure of the provision of network nodes to ensure sustainable operation of the network to improve survivability of the infocommunication network functioning.
Keywords: Infocommunication network – Survivability – «Betweenness» – Reservations – Node.
O. N. Degtyarev, V. A. Kudryavcev
PUMP TESTING STAND MODERNIZATION
The output of the aircraft equipment was reduced after disintegration of the USSR. Problems of creation of the special test and measuring devices applied at modernization and repair of the aviation equipment became actual. The purpose of the work is modernization of pump test stand – a component of hydromechanical system the ГП-21 drive generator which is the main source of power supply on aircrafts. The upgraded stand provides maintenance of the set temperature of working liquid in the range of 100 - 140 °C with a margin error ±5 °C. Into the system of temperature regulation are included PID regulator РП1-3 and digital temperature gauges firm "РегМик" (The Chernigov Region). The system of regulation is debugged directly on the object and transferred to the customer – the aircraft repair enterprise "МИГ-ремонт" (Zaporozhye).
Keywords: Measurement –Regulator – Range –Error –Stand.
А. G. Stepanenko
METHODOLOGICAL PROBLEMS OF THE TRAINING FOR SEAFARERS IN VIEW OF THE REQUIREMENT OF MANILA AMENDMENTS TO THE INTERNATIONAL CONVENTION ON STANDARDS OF TRAINING CERTIFICATION AND WATCHKEEPING FOR SEAFARERS (IC STCW 78)
Sets out the requirements of the Manila amendments that have made significant changes in training requirements for masters and chief mates are given. Five programs, where all requirements of amendments-2010 are considered, for training courses are developed. The analysis of the problem of simulator training students in light of the requirements of the Manila amendments to the STCW IC is done. In these programs, special attention is given to practice skills on simulators and practice sessions.
Keywords: Navigation Simulators, Maneuvering, Mooring, Harbor Water, Difficult Conditions
ANALYSIS AND JUSTIFICATION OF NETWORK WIRELINE ACCESS PARAMETERS SELECTION
The executed researches belong to the area of perspective access networks design. The work is devoted to the access networks parameters analysis and to the choice of the most significant among them. Results of researches for wire decisions of the network organization are given.
Keywords: Access network; Parameters of access networks.