Refrigeration engineering and technology

12-16

Authors: N.V. Zhikhareva

The paper describes the features of air conditioning systems design for indoor year-round operation pools. The features of humid heat load calculation and air consumption of air conditioning swimming pools air consumption are shown. According to studies, a comprehensive model for calculating of swimming pool air conditioning, including the determination of optimal parameters definition of insulation thickness economic feasibility has been carried out. Selection of air conditioning system was made.

21-29

Authors: А.S. Lukiyanova

Taking note of bulk viscosity is especially important at the description of high-intensity processes, such as explosion, a flow with high speeds, the acoustic phenomena, and also in characteristic points of a condition of substance. Bulk viscosity characterizes ability of substance to transformation of mechanical energy in thermal at nonequilibrium volume deformation. In the work the main theoretical directions of bulk viscosity influence studying are considered: physical acoustics, hydrodynamics, molecular and kinetic theory of gases and liquids. It is established that the molecular mechanism of the bulk viscosity emergence described in Landau's Enskog, Kramer works allows more deep understanding of the physical processes which are taking place at change of volume in the compressed liquid. Special interest is submitted to the theory of relaxation proposed by Mandelstam and Leontovich where the equation of a state includes the parameter defining internal structure of liquid that allows to consider effects of acoustic waves distribution. Expediency of Green-Kubo formula application which connects bulk viscosity with autocorrelation function of pressure microscopic fluctuations is noted. The existing methods of bulk viscosity coefficient experimental determination such as acoustic spectroscopy and Brillouin-Mandelstam scattering are analyzed. Problems of bulk viscosity near a critical point liquid-gas determination are considered.

37-44

Authors: V. P. Zaykov, V. I. Mescheryakov, Yu. I. Zhuravlev

A comparative analysis of the basic parameters and reliability indicators of the single-stage thermoelectric cooling devices while using different combinations of settings compared to traditional initial materials of a similar efficiency for changes in temperature from 0 to 60 K and operation modes from maximum cooling capacity to the minimum failure rate is presented. It is shown that the use of initial materials with higher conductivity compared to the traditional means to increase the cooling capacity or to reduce the number of elements, to increase the thermoelectric cooling power, to reduce the failure rate and thereby to increase the probability of thermoelectric cooling device failure-free operation. It was obtained the simple ratios of interrelation of parameters and indicators of reliability for a variety of combinations of initial materials depending on the thermoelectric cooling power and temperature differential. It is shown that under the condition of a constant heat load and temperature difference parametric constants of thermocouples amount on the thermoelectric cooling capacity production. Analysis of the traditional version failure rate and other combinations of failure rate had helped to identify that the failure rate production on the maximum thermoelectric power is a constant for any combinations of the parameters of the source material, for any operation mode and temperature difference. The possible application of the superposition principle when building a single-stage thermoelectric cooling devices of a high reliability by combining of a constructive method (mode selection of thermoelectric cooling devices) and parametric method (selected combinations of the initial material) were discussed. It’s shows the application of the principle of superposition of structural and parametric methods of construction of thermoelectric cooling devices could significantly increase the reliability of thermoelectric cooling devices.

53-59

Authors: V.Y. Labay, D.I. Harasym

Nowadays for Ukraine the problem with saving energy resources is especially relevant in a conditions of market economy, where the main energy carriers, such as oil and gas, are limited. That’s why in the last decade with the aim of saving energy resources the fundamental researches of activity of different branches, manufactures and technologies from positions of exergy methodology are held abroad. Today cost estimates can’t be the only measure of effectiveness of energy equipment which recycles energy resources. Exergy is physical, not economical criterion and determines independence of this parameter from price fluctuations. The application of exergy allows to give objective assessment of energy resources of any type as it is the only measure of working capacity, applicability of energy resources. There are many examples of successful application of exergy methodology by technical and economical optimization in industry, especially in energy intensive branches. The minimum should be determined by exergy losses per unit of provided heat, not by financial costs. The analysis of exergy effectiveness of implemented central straight flow air conditioning system (ACS) for operating cleanrooms which was obtained on its innovative mathematical research model depending on different factors that have influence on its work was presented in this article, and ways of energy saving for this ACS was proposed. It was found that the biggest impact on exergy output-input ratio of its air conditioning system have the temperature difference between inside and supplied air in a room, temperature of inside air which is depends on temperature of outside air, and coefficient of transformation EER of chosen refrigeration machine of air conditioning system. It was shown that with the aim of energy saving the implemented air conditioning system should be preferably used at a higher temperature difference between inside and supplied air, for example, = 9,0°С (at any temperature of inside air) and at higher coefficient of transformation, for example = 4,0, which gives the opportunity to get the highest exergy output-input ratio , which means to get the most energy saving variant of exploitation of implemented air conditioning system.

65-69

Authors: L.I. Morosuk, S.V. Gaiduk, B.G. Grudka

Development of small agricultural production outside the settlements is constrained by the technical difficulties of implementation and cost of centralized power and heat supply. Low power energetics is capable for combined production of electricity and heat in a cogeneration system. Further energy efficiency increase of a small power plant is provided by trigeneration, wherein one kind of primary energy is transformed simultaneously in the three beneficial effects: electricity, heat and cold, which are equally needed to agricultural production. In the particular example of the farm, which has quarters, greenhouse and cold storages, the needs of recovered heat during the year were calculated, set a reserve and recommendations for its redistribution between the two beneficial effects: heat and cold, in accordance with the technological process of agricultural production were made. It is shown that the trigeneration system is capable of providing high energy efficiency of small autonomous power plant in the agricultural sector.

75-81

Authors: K. V. Agyeyev , A. E. Denysova

The paper considers the basic theoretical concepts of vortex motion in relation to the solution of technical problems. The issue of instability of spiral vortex spatial structures when doublet or triplet of vortex filaments occurs is considered on the basis of the vortex theory. The problem of current importance is investigation of existence parameters for swirl or spiral shape disturbances. The disturbances so called processes with precessing vortex core (spiral shape vortex). The assessment of heat engineering equipment, in particular, recuperative heat exchangers is conducted. It is displayed that heating engineering units – vortex devices such as vortex combustor, combustion chambers etc. – have considerable advantages due to the operation in the active hydro–gasdynamic modes, and efficiency of their work is mainly depends on the operating and design parameters. The vortex effect that occurs in these devices allows making them compact, with an increased energy efficiency ratio, which corresponds to the objectives set in the Energy Strategy of Ukraine 2030. A construction of the jet-vortex compact recuperative heat exchanger, the operation features of which are in good agreement with the theory of the concentrated vortices, is given. It is displayed that the work of the jet-vortex recuperative heat exchanger is not completely identical to the cyclone vortex heat exchangers by the nature of the processes occurring there. The process of making decisions on the design parameters of a physical model (a cold aerodynamic experimental unit), its aerodynamic calculations and the selection of parameters for CFD-simulation of jet-vortex recuperative heat exchanger is considered. A technique for research on a physical model and its design is represented. The operation of the experimental unit is described. According to the results of CFD-research for recuperator operation, the high adequacy of the numerical CFD-model developed on the basis of the physical and simulation modeling results is presented.

92-96

Authors: J. Kozonova, N. Povarova

Functional foods market is changing rapidly. Now the market has the highest growth. In the European Union food producers try to fit virtually every product under the "functional" definition. In this article we will review major trends in the EU functional foods market and try to analyze them. It is well known that foods fortified with nutritional and disease-preventing qualities are invigorating the world food industry. Health-conscious consumers are driving the demand for products that aim to promote better health, increase longevity and prevent the onset of chronic diseases. With a fast-emerging middle class, more disposable income, and a greater number of working/more educated women in emerging markets, the worldwide potential for functional foods/beverages is unprecedented. Milk formula, energy drinks, probiotic yogurt, juice drinks, sports drinks, cereal, and biscuits were among the top-performing functional global health and wellness food categories in 2014. There is a breakout of the year's top trends driving the market for functional foods and beverages. A review of recent deal drivers, the fastest-growing products and innovation trends can help businesses identify the most promising entry points to this market.

102-107

Authors: N.A. Kniazieva, A.S. Kalchenko

The method of controlling the quality of services in next generation net-works using the theory of fuzzy sets is presented in the paper. The algorithm of the quality of services management system is given. The proposed method of service quality management can effectively monitor and maintain the degree of users satisfaction with the services at the required level.