Volume 51 Issue 2
Section 1. Refrigeration engineering
RESEARCH OF PERSPECTIVE FOR NEON-HELIUM MIXTURE ENRICHMENT HEAT AND MASS NOZZLE COLUMNS SURFACE CHARACTERISTICS
One of the main factors determining nozzle rectifying columns operation is the mass exchange sur-face. The presented researches focus on the choice of nozzle design unit for neon helium mixture pri-mary enrichment. Created universal experimental setup for studying the processes of rectification al-lows obtaining the basic characteristics of four nozzles: spiral, spiral-prismatic and two types of mesh saddle (10´10´0,2 mm and 12´12´0,4 mm). From the studied nozzles according to known requirements and taking into consideration a large-scale factor the best mesh saddle nozzle from a wire with a diameter 0,2 mm and the sizes 10×10 mm was chosen. This type of nozzle has low resistance of the irrigated nozzle (48 Pa) that is critical for the studied steam speeds (0,3 … 0,5 m/s).
Key words: Rectification – Neon-Helium Mixture – Nozzle Column – Heat and Mass-exchange Surface – Transfer Unit Height.
TECHNICAL FEATURES OF BINARY ICE SCREW TYPE GENERATORS DESIGN
In the paper the technical features of binary ice screw type generators design are considered. The basic element of this type machines is a pair heat-exchanger-screw. The heat exchanger may be deformed. Screw in the process wears out. During work with the oscillation loading at a subzero temperature there are problems that result in the decline of efficiency or machines breakage. Recommendations on planning of machines of this type are given. In addition, work of screw generator is considered in a pair with the accumulator of cold. Using of accumulator reduces capital and operational costs. A properly designed heat balance of such a system will make it possible to minimize internal losses of cold. The complete chart of setting of this type is presented. The machine operation modes are analyzed.
Key words: binary ice – ice-slurry – screw icemaker
V. N. Kukharenko, V. V. Kuznetsov
DEVELOPMENT POSSIBILITIES OF NEW STIRLING REFRIGERATING MACHINES ON THE BASIS OF EXISTING CONSTRUCTIONS
In the given paper the possibility of new Stirling refrigerating machine development on the basis of existing design has been considered. For refrigerating machine process analysis the isothermal model of Stirling cycle and method of separate loss analysis were used. Ambient and cooling temperatures were assumed constant in equation for cooling capacity calculation. The dimensionless complexes, namely, ideal cooling capacity and complexes taking into account cooler regenerator losses due to non-ideal heat exchange, hydraulic resistance and axial matrix heat flow have been obtained after mathematical transformation of the governing equations. According to the theory of similarity the pairwise equalities of heat exchanger volume simplexes (targeted volume divided by volume of refrigerator expansion space) and dimensionless complexes is needed for similarity of new and basis Stirling refrigerating machine. The equality of dimensionless complexes is achieved with equal regenerator length for both new refrigerator and basis cooler. For confirmation of this conclusion the basis refrigerator KGM-9000/80-1 with known experimental data and new designed refrigerator with cooling capacity 200 W have been used. For parameters calculation of refrigerators the one-dimensional mathematical model based on structure-module approach was used. The identical effectiveness for both coolers has been obtained. Variation of maximum pressure and working frequency of cycle does not allow creating new similarity Stirling refrigerating machine due to complicated influence of these parameters on dimensionless loss complexes. The procedure of effectiveness and refrigerating capacity increasing while changing the working frequency and maximum pressure for new refrigerator also has been shown.
Key words: Stirling refrigerating machine - Cooling capacity losses - Dimensionless complexes - similarity.
V.Y. Labay, D.I. Harasym
INFLUENCE OF COEFFICIENT OF TRANSFORMATION OF REFRIGERATION MACHINE ON EXERGETIC OUTPUT-INPUT RATIO OF AIR CONDITIONING SYSTEM FOR CLEANROOM
Exergetic method is a universal way of thermodynamic research of various processes of energy transformation in energy technological systems, to which air conditioning system for cleanroom belongs. Implementation of exergetic analysis for energy technological system makes it possible to determine the influence of various elements of its system on its work and because of this to increase the effectiveness of work of energy technological system in general. Effectiveness of work of any air conditioning system depends on energy effectiveness of refrigeration ma-chine, which serves it and consumes electricity for reducing the heat of supply air which enters the room. And it means that the main purpose of selection of certain refrigeration machine for air conditioning system is to reach the maximum cooling capacity with minimum energy consumption. Innovation mathematical research model of the central straight flow air conditioning system for cleanroom in order to computer estimation of its energy effectiveness by virtue of exergetic output-input ratio depending on different factors, which have influence on its work, in particular the coefficient of transformation EER of its refrigeration machine was used in this article. The dependences of exergetic output-input ratio of chosen air conditioning system for cleanroom on coefficient of transformation EER of its refrigeration machine by different parameters of outdoor and indoor air and the temperature difference between the indoor and supply air were presented. It is shown, that the chosen air conditioning system should be preferably used by higher coefficient of transformation EER of its refrigeration machine and higher difference between temperatures of indoor and supply air by various temperatures of outdoor air, that will give the opportunity to gain the highest exergetic output-input ratio , which means to gain the most advantageous economical variant of exploitation of chosen air conditioning system.
Key words: Exergetic balance - Air conditioning systems - Cleanrooms - Exergetic efficiency - Coefficient of transformation EER
Section 2. Power engineering and energy saving
А.V. Doroshenko, A.R. Antonova, K.V. Lyudnitsky
SOLAR MULTI-STAGE ABSORPTION REFRIGERATION SYSTEMS BASED ON FILM TYPE HEAT-MASS EXCHANGE APPARATUSES
The paper presents the developed circuit solutions for alternative refrigeration systems based on the of heat-absorption cycle and solar energy utilization for regeneration (recovery) of the absorbent solution. Cascade principle of heat-mass exchange apparatuses construction was ap-plied, of drying and cooling loops with varying of temperature level and increasing of absorbent concentration on the cascade steps. Film type heat and mass transfer equipment, which is the part of the drying and cooling loops is unified and executed on the basis of monoblock polymeric materials compositions. The preliminary analysis of solar refrigeration systems potentialities was carried out.
Key words: Solar systems; Dehumidification; Medium cooling; Heat-mass transfer equipment; Film flows; Absorption; Desorption; Evaporative refrigeration.
A.N. Radchenko, О.V. Ostapenko
HEAT TRANSFORMATION IN THE PLANT FOR INTEGRATED ENERGY SUPPLY BY LITHIUM BROMIDE ABSORPTION MACHINE
The efficiency of waste heat transformation from gas engines in the plant for integrated energy supply by lithium bromide absorption refrigerating machine was analyzed. Such gas engines are equipped with heat ex-changers for producing hot water from the engine recoverable heat. The waste heat from gas engine jacket and lubricant oil cooling water, scavenge gas-air mixture and exhaust gas are used to produce hot water with the temperature of about 90 °С as heating source for absorption chiller. The analysis was made for trigeneration plant on the base of cogeneration reciprocating gas engine modules JMS 420 GE Jenbacher (electrical power output of each cogeneration gas engine 1400 kW, thermal power output 1500 kW). This trigeneration plant was designed for combined energy supply of the factory "Sandora"–"PepsiCо Ukraine" (Nikolaev, Ukraine). The trigeneration plant, equipped with two cogeneration JMS 420 GE Jenbacher gas engine modules and a single-stage absorption chiller, has been designed and assembled by "Sinapse"–"GE Energy" (Kiev) and "Khladotechnika" (Nikolaev). The absorption chiller produces chilled water for technology process cooling and conditioning of engine room intake air. The significant heat losses were revealed caused by the cogeneration gas engine modules and the lithium bromide absorption chiller temperature regime performance discrepancy. In its turn it was caused by the increased temperature of return water from the single-stage absorption chiller of about 75 °С to the parts of the gas engine to be cooled. But in respect of the condition of engine reliable maintenance at the appropriate thermal rate the temperature of the return cooled water entering the engine cogeneration system is limited to the design value not exceeding 70 °С. If it excess, a surplus heath of return water is rejected to the atmosphere by the cooling tower. Return of excess heat to a single-stage absorption chiller is impossible because of its temperature of 75…78 °С lowered rather design temperature of the supply hot water for a single-stage absorption chiller of 90…95 °С. Fall of temperature of the supply hot water to a single-stage absorption refrigerating machine would cause considerable dropping the efficiency of transforming a gas engine recoverable heat into a cold – decrease in coefficient of performance (COP) from nominal (design) value of about 0.7 to 0.5 and lower. The results of water temperature and flow measuring showed the heat losses of 30...40 % of the heat transformed by absorption chiller into a cold. There were proposed an improved two-stream system of return water flow to the cogeneration gas engine modules that reduces the heat losses compared with traditional one-stream variant. In the two-stream system the water mass flow through cogeneration gas engine modules and absorption chiller is increased up to about 150 % compared with the base variant and the return cooled water flow from the absorption chiller is divided into two streams. With this the temperature of the supply hot water for the absorption chiller, leaving the cogeneration gas engine modules, and the temperature of return cooled water from the absorption chiller is lowered as compared with the base one-stream system. One of the return water stream – of the same mass flow as in the base variant but at the lowered temperature – is cooled down to the required temperature of 70 °С as in the base variant and directed to the gas engine nodes those need cooling. The other (addition) return water stream of the 50 % mass flow and of increased temperature higher than 70 °С is delivered directly to the gas engine exhaust gas recovering boiler (economizer) by-passing the gas engine cooling nodes. It was shown that the two-stream system of return water flow to the cogeneration gas engine modules increases cooling capacity by approximately 25 % compared with traditional one-stream variant due to reducing the heat losses during transformation of gas engine waste heat into a cold.
Key words: trigeneration, соgeneration module, lithium bromide absorption chiller, gas engine.
Section 3. Refrigerating and accompanying technologies
FROZEN SEMI-PRODUCTS FROM BEANS FOR RESTAURANT BUSINESS ESTABLISHMENTS
The article shows the feasibility of using lentils which is a valuable raw material with high content of protein and carbohydrates. It was scientifically substantiated that germination of lentils process significantly improves its assimilation in the human organism. It was proved that during the germination the starch content decreases as a result of amylase effect, which is cleaved with forming a significant amount of dextrin. It was also proved that germination of lentils improves digestion of proteins that constitute it, increases the mass fraction of vitamins, reduces the duration of the product heat treatment. It is shown that germinated lentils can be used immediately after germination or kept refrigerated or frozen, which allows to make a meal after the semi-products order for 12…15 min and greatly intensifies technology.
Key words: freezing; lentils; germination; moisture exchange; protein; starch; organoleptic properties.
EQUATIONS FOR REFRIGERANT R134a VISCOSITY AND THERMAL CONDUCTIVITY CALCULATION
Equations for alternative refrigerant R134a viscosity and thermal conductivity calculation expressed in terms of independent variables, such as temperature and density are worked out. Equation coefficients are determined by the least square technique according to the experimental data. The equations describe viscosity at temperature ranging from 248 to 439 K at a pressure up to 6,0 MPa and thermal conductivity at temperature ranging from 248 to 533 K at a pressure up to 60,9 MPa. The composed equations accuracy is quite acceptable for the engineering calculations.
Key words: Refrigerant – R134a – Viscosity – Thermal conductivity – Equations.
J. Kozonova, А. Avdeeva
FUNCTIONAL VEGETABLE SALADS WITH ALGAE
Now on the Ukrainian market frozen vegetable salads are well represented. They contain a small amount of protein and have an unbalanced composition nutrientny. Adding algae to the vegetable salads composition allows to resolve this contradiction. In this paper the functional vegetable salads expanding assortment possibilities are represented. The product components composition was designed. It is advisable to add different types of algae (kelp, spirulina and fucus) to the quick-frozen functional vegetable salads for nutrient correction and rising in nutritional value. For the product manufacture modern raw materials low-waste processing technology was used. The selected process conditions, as well as preservation method provide finished product high quality and nutritional value. This product is recommended for all population groups, as well as for people with poor health.
Key words: functional properties; vegetable salads; frozen products; spirulina; kelp; fucus.
HEAT PUMP INSTALLATIONS CHARACTERISTICS ANALYSIS
Heat pump installation are very efficient heating and cooling systems and can significantly reduce your energy costs. The technical and economic performance of a heat pump is closely related to the characteristics of the heat source. This paper presents an overview of different heat sources for heat pumps, recommendation for designing this systems. The heat source temperature and its constancy during a year depend very strongly on the type of heat source. The heat pump performance were analyzed using ground and air temperatures for Odessa. The results of research indicate of natural temperature distribution in ground. Areas of natural temperature distribution in ground demonstrate short and long-term fluctuations of temperatures. Short-term fluctuations are influenced by weather and they exist only up to 1 m below ground surface. Long-term fluctuations (known also as seasonal fluctuations) occur in the second area (up to 8 or 20 m depending on the ground type). In deep area for every particular ground type temperature stays constant and very slowly increases with depth according to geothermal gradient, which indicates thermal impact of Earth's inner core.
Key words: Heat pump – Low-grade heat - Temperature - Heat flow – Effectiveness
Section 4. Automatic, computer and telecommunication technologies
A.A. Gnatovskaya, T.B. Vokhmentseva, L.B. Kovalenko, S.D. Kuznichenko
TWO-CASCADE THERMOELECTRIC DEVICE RELIABILE-ORIENTED DESIGN IN CAD OF CRITICAL SYSTEMS
The paper deals with the design of thermally loaded vehicles with two-stage thermoelectric cooling devices in CAD critical systems. In the design of thermoelectric cooling devices thermally loaded elements that are part of the critical information systems, an integral characteristic is reliability. The fundamental approach to ensure the reliability is the parametric method, because the failure rate of the components are naturally included in the resulting intensity of a system failure. The importance of the parametric approach for the design of reliable information systems and its constituent components predetermines considerable attention to the development of computer-aided design in this direction. Research is aimed at solving problems of increasing the reliability of thermal loaded funds with cascade thermoelectric cooling devices that occur in CAD of critical information systems in a wide range of thermal loads, are relevant. Application of cascade thermoelectric cooling devices provides the highest reliability in comparison with other types of coolers. Quantitative estimation of reliability indices is crucial in the early stages of design and development tools of thermal-critical systems. The implementation of a subsystem CAD parametric models of the relationship of reliability and the basic parameters of a two-stage thermoelectric cooling device based on the selected mode of operation are proposed. Using this model allows to carry out reliability-oriented design of a two-stage thermoelectric cooling device in CAD critical systems. CAD subsystem provides quantitative estimation of the failure rate and probability of failure of the two-stage thermoelectric cooling devices at the design stage in accordance with the specifications. When designing the thermal-funds, proposed by CAD, calculated parameters of two-stage thermoelectric cooling devices provide the minimum failure rate, which is the determining criterion. Comparative analysis of calculated data for the basic parameters of a two-stage thermoelectric device of specified design shows a choice of current modes of functioning, capable of predicting and significantly improve the performance of the failure rate and the probability of failure-free operation.
Key words: Reliability-oriented design – Thermoelectric devices – Reliability – Critical Information Systems – Heat-loaded elements.
S.S. Surkov, A.N. Martynyuk
AUTHORIZATION FOR AUTOMOBILE HEADUNIT WITHOUT BROWSER SUPPORT WITH MOBILE DEVICES THROUGH BLUETOOTH
Along with the crucial growth of information-technologies the communicability of the society is rapidly developing. Multiple social networks is the brightest example of this fact. All automobiles manufacturers strive to provide embedded computers with access to the Internet, but some embedded computers does not have a built-in browser. To solve the problem of applications authorization protocol OAuth was created, the aim of which is to enter Web-browser accounting data. This paper describes the implementation of the OAuth realization solution for embedded computers that do not have browser support. All social networks such as Facebook, Twitter, Google+, Foursquare, Evernote, VK provide WEB REST API which allows to create native application easily for any platform which have internet access. The communication is going through Bluetooth. As access to internet is implemented via Bluetooth protocol there won’t be technical difficulties to use the app. This method could be implemented as for iOS (headunit is needed to be MFI certified) or for Android. This paper describes the solution of implementing OAuth for headunits which without browser support.
Key words: Authorization Method – Headunit – OAuth – REST API – Smartphone – iOS – Android