Refrigeration engineering and technology

10 - 13

Authors: A.S. Boychuk

Equations for thermal conductivity of alternative refrigerants R32and R125 for variable temperature and density were worked out. The reliable equation of state was used for each refrigerant. Coefficients of the equations were determined by least-square method on the experimental data. The equations describe the thermal conductivity in the temperature range from 223 to 466 K at pressure up to 50 MPa for R32and from 228 to 513 K at pressure up to 53 MPa for R125. The accuracy of the equations is acceptable for engineering calculations.

20 - 25

Authors: А.N. Radchenko; A.V. Grich

Based on the analysis of the cooling performance of trigeneration system gas engine room intake air the rational way of cooling by supplying a cooled intake air to the inlet of turbochargers and to the alternators and cylinder heads of the cogeneration gas modes and ventilation of the main volume of engine room was developed.

32 - 42

Authors: A.V. Doroshenko; K.V. Lyudnitskij

The worked out schematics for the alternative refrigeration systems and air-conditioning systems, based on the utilization of absorption cycle and solar energy for the regeneration (renewals) of absorbent solution were presented in the paper. Factorable principle of construction of all heat-mass-transfer apparatuses is used with varying of both temperature level and growth of absorbent concentration on the cascade stages. Heat-mass-transfer apparatuses are compatible and executed on the basis of multi-stage monoblock compositions from polymeric materials. The preliminary analysis of possibilities of the solar systems was executed as it applied to the tasks of environments cooling and air-conditioning.

47 - 53

Authors: S.V. Artemenko

The review of recent papers related to modeling of refrigerant properties using artificial neural networks as an alternative to conventional thermodynamic approach for modeling prediction of thermodynamic properties of refrigerants has been given in the paper. The study also discusses efficiency, adequacy and limitation of this approach.

59 - 66

Authors: M.A. Kolosov; V.Yu. Emelianov

One-dimensional transient thermal model of the lengthy HTS conductor using thermoresistive effect to measure the level of cryogenic liquid was created. Resulting model made it possible to determine the distribution of pace-tures along the length of the HTS conductor and other characteristics. The comparing-of calculated and experimental data obtained at an atmospheric dewar with liquid nitrogen was carried out.

71 - 74

Authors: S.V. Sakharova; S.V. Rybka

The subject of the research, some results of which are presented in this paper, is focused on the development of modern telecommunication networks in Ukraine and allows solving the problems at the networks design and organization of access to infocommunication services. The chosen theme is closely related with the main directions of the world telecommunications development, which are defined in the main existing regulations and laws. A characteristic feature of computer information systems’ progress, which are actual in Ukraine, is an absolute priority of expert systems’ development. Questions of the expert systems’ usage at the design and development of telecommunications networks in the modern world are considered in the paper. The problem of expert system’s development, which allows enhancing of the design and operation of telecommunication and access networks, is being solved within the given work. Statement of the problem is limited by the development of the algorithm for the expert system’s development and analysis of the theoretical aspects of the knowledge based intelligent system’s design. Done work formulates the qualimetry problems and helps to understand how to build an expert system for the access networks’ rational development. Expert system, allowing to choose proper access technology, is developed as an example. Particularly DSL technologies are considered at the first stage. The last mile is quite specific network’s segment. It should have enough bandwidth while providing great transmission range without regenerators. This expert system will determine the best option of DSL technology on the basis of the desired properties. The system is developed with the usage of Expek Pro software (version 1.5+) for Windows. The article consists of five sections - introduction, problem statement, the main part - the necessity of an expert system’s development for the telecommunication networks’ design, an example of the developed expert system and conclusions, as well as includes bibliography, used at the work writing.