Refrigeration engineering and technology

17 - 20

Authors: A.N. Gorin; A.B. Kudrin; M.V. Domin; O.N. Burdiyan

Experimental researches of temperature distribution on the evaporator surface of the household DH-239 refrigerating appliance working at isobutane depending on a charge dose of refrigerating system are conducted. The received results can be used for microleaks diagnosing methods development during household refrigerating appliances operation.

25 - 30

Authors: А.Е. Lagytin; P.F. Stoianov

Finned heat exchangers are the basic type of heat exchanger employed in many industrial applications such as refrigeration, air conditioning and other thermal processes. This paper presents experimental research of air-side heat transfer of finned surfaces. Seven types of finned surfaces are employed in this study. Investigation describes temperature fields and temperature cooling air-flow changing in the inter-fin duct without taking into account tube section. Temperature difference in-between local real air temperature data and fin surfaces are determined. The air-side heat transfer coefficients of finned tubes were evaluated at various air flow rate. Experimental setup was designed to simulate a single passage in a fin-tube heat exchanger. The heat transfer improvement of finned surfaces is a problem which includes several factors. Among the main factors are the fin form and its material. A series of tests presented in this paper reveal visual and quantitative details of local fin-surface temperature distributions for steel and aluminum fins. The air-side thermal performance data of finned surfaces were analyzed using conditional coefficient of heat transfer. Tube displacement in regard to fin on its thermal characteristics is evaluated. Experimental results have also shown that edge type of the inter-fin duct is not influenced on heat exchange performance. The results of research indicate that conditional coefficient of heat transfer can be used for performance comparison of finned heat exchange surfaces. This method is very useful for simple heat transfer estimation of finned surfaces for a wide range of practical applications.

35 - 46

Authors: A.V. Doroshenko; V.A. Goncharenko

Scheme solutions of heat-cold supply and air conditioning combined solar systems, based on the open absorption cycle with an absorbent indirect regeneration and new types of heat-mass exchange apparatus with “gas- liquid- solid body" movable nozzle utilization were developed. For the first time evaporative air and water coolers of indirect type with regular structure nozzle and mobile-three-phase layer placed between the nozzle heat transfer elements, which increases the homogeneity of the moving layer processes and growth of the of heat-mass-transfer processes efficiency were developed. On the basis of theoretical and experimental research practical recommendations for determining solar systems optimal mode parameters and geometric parameters of the main elements of heat-mass-transfer equipment have been worked out.

55 - 60

Authors: О. Pylypenko; А. Forsiuk; Ya. Zasiadko; V. Glushkov

The use of correlations that would be capable to adequately account for the heat transfer between the surface and refrigerant are crucial for the accurate design calculations and proper heat transfer equipment sizing, including cold accumulators with ice generation on the heat transfer surface. A vast multitude of such correlations for the determination of overall heat transfer coefficient valid for different cross sections pipes and processes conditions are available now in the literature. The calculations of heat transfer pertinent to the conditions of cold accumulators, lead to the results drastically deviating from those obtained in the framework of the direct experimentation carried out at the Department of Power Engineering and Industrial Refrigeration of NUFT. In order to mark one or some of such correlations, that might have been used within the engineering calculations under condition of their proper correction, the critical comparative analysis of the literature sources has been carried out. The mathematical modeling of the heat transfer process in the condition of boiling refrigerant, with taking into account the valid limitations towards correlations, has been performed. The graphical comparison of the modeling results calculation with chosen correlations is performed. The results of the analysis allowed choosing the correlations, which could be recommended to be used within the engineering design calculations of cold accumulators with the ice accumulation on the heat transfer surface. The applications of such design correlations that adequately reflect the mechanism of heat transfer between the surface and refrigerant would be critical for the accurate design calculations of the transfer equipment of the refrigeration units, including cold accumulators with ice generation.

69 - 75

Authors: L.N. Yakub

The results of the calculation of the thermodynamic properties: density, enthalpy, entropy, volume expansion coefficient and heat capacity of the solid polymeric nanocrystal - C60 at low temperatures in a wide range of pressures using theoretical equation of state are presented.