Refrigeration engineering and technology

11-15

Authors: A. A. Vasserman, A. S. Boychuk

Equations describing viscosity and thermal conductivity experimental data of refrigerants R125/R134a mixture are compiled. Coefficients are determined by the least square technique. Equations represent refrigerants mixture viscosity and thermal conductivity dependence from temperature, density and composition. Providing possibility to calculate mixture viscosity at temperature ranging 298…423 К at a pressure up to 6,0 MPa at subcritical and 248…345 К up to 2,8 МPа at supercritical densities. Thermal conductivity is described at temperature ranging 298…423 К up to 6,0 MPa at subcritical and 232…323 К up to 20 МPа at supercritical densities. Standard and maximum deviations of the experimental values from calculated do not exceed 3,1% and 5,3% for viscosity and 2,2% and 5,0% for thermal conductivity.

21-36

Authors: A. V. Doroshenko, V. Kh. Kirillov, A. R. Antonova, K. V. Lyudnitskij, V. V. Melekhin

The fundamental decisions of water and air evaporative coolers of direct and indirect type are developed with the lowered limit of cooling (in relation to the temperature of wet thermometer of entering to the cooler current of air). Heat-mass-transfer apparatus of film-type is executed on the basis of multichannel compositions from polymeric materials with the channels of intricate configuration. A mathematical model describing the common heat-mass-transfer processes in the evaporative coolers of indirect type (IECg and IEC-Rg) has been proposed, the comparative analysis of the developed evaporative coolers abilities has been carried out on the basis of the obtained experimental data on heat-mass-transfer processes efficiency. The initial parameters (temperature and humidity ratio) of air flow and contacting flows of gas and liquid correlation were varied in the experiment. The special attention has been spared to the features of heat-mass-transfer processes flowing at the low temperature water and air cooling.

42-48

Authors: N. V. Zhіkhareva

Using the basic principles of simulation the method for calculating of the annual consumption of cold by air-conditioning systems was developed. The initial data are: location of the building and the local weather conditions according to the long-term supervision; estimated barometric pressure; the number of working days, shifts; mass flow rates of the supply air G, outdoor air GH and recirculation Gp; coefficient of recirculation; constant or variable value of the enthalpy of recycling air hp and cooled air hoh; temperature (°C) and the enthalpy of the indoor air. On the basis of the database of the table monthly averages of temperatures tn.m (°C), outdoor air and water vapor partial pressure PH (kPa) the monthly average enthalpy hn.m. using the splines interpolation method, the total share of cold per unit of air conditioning systems air flow, the annual consumption of cold, taking into account the dimensionless factors are determined. The developed method allows to compare the alternative variants of air conditioning systems in the optimization problem.

52-60

Authors: Y. К. Коrnіenко, Y. S. Fеdchеnkо, F. А. Trіshyn

The article dwells upon the experience of implementation and application of support learning based on Moodle, which has been created and applied in the Odessa National Academy of Food Technologies since 2014. The role provided for the distance education programs is emphasized, the benefits of system based on Moodle are proved in a well-argued manner: the system is freely distributed, simple to install on any platform that supports PHP; it is spread among many institutions of higher education; it has a multilingual interface (including supported Ukrainian, English), designed to meet the advances of modern pedagogy (focus is on the interaction between the students, forum discussion); has a simple, "easy", efficient, compliant web-based interface. Besides, the system provides great possibilities to conduct assessment of knowledge. It is noted that at this stage of application of the system based on Moodle is used in the academy to support traditional education as intramural and extramural forms of study, including the organization of independent work of students. Distance Learning Center website was developed by e-mail: http://moodle.onaft.edu.ua/, requirements document, the Center operates by, were prepared and approved. Along with installing Moodle software environment it was made possible to design distance learning courses on server hosting registration. It is noted that the present system of distance learning of ONAFT contains 285 distance learning courses filled with the necessary teaching materials. In general, 190 teachers are recorded as well as more than 3,000 students of all faculties of the academy and this number is growing. The requirements that developers of distance learning courses must consider are described. Examples of already created distance learning courses, their composition and characteristics are given. Some of them are offered teachers as a model for creating your own courses. Special attention is paid to the test control of knowledge required for current control of students' knowledge. The main types of tests, such as Multiple choice, Matching, Numerical, Essay, due to their features and settings are considered. Hereafter the mechanism of creation of these types of tests is explained on examples. Considerable attention is paid to the Journal of levels, which contains test results. Quality of creation of tests is analyzed, quality parameters are provided, the means to improve this quality are offered. The latest can be done by the application of external resources in the system Moodle, for example, by applying of such online resource as LearningApps.org.