Vol 104, No 1 (2015)

Theoretically possible cooling capacity of an ideal refrigeration system using the effective radiation into space was calculated by two methods. The calculations were performed for the cities located from 43 ° to 59 ° north latitude: Almaty, Vladivostok, UstKamenogorsk, Petropavlovsk, Omsk, Kazan, Moscow and St. Petersburg. The graphs of the total amount of cold for the year and for some months depending on the temperature of the radiating surface are shown. It is found that the greatest amount of cold for the year can be produced in the climatic conditions of the city of Omsk, and the smallest in Almaty. A method for estimating the amount of heat withdrawn from the radiator due to convective heat transfer through the cooling degreehours is developed. The results of the calculation of the cooling degreehours for the year for all of the above cities are presented. Also graphs in the article are showing how many hours per year the temperature in each of the cities is below given temperature. With the help of these graphs it is expected to make an assessment of the working time of the refrigeration system during the year. In the summer period due to effective radiation the coolant temperature can become not lower than 15...20 °C. In the winter, it is impossible to use the effective radiation for stable cooling to a temperature below -10 °C all reviewed cities. The data obtained can be used in the design of cooling systems of the considered type, as well as in the standard refrigeration systems that use natural cooling (Free cooling).

Hardphase materials having special magnetic, electric and mechanical properties are needed for microelectronics, hightemperature conductors, computer engineering and other modern fields of engineering and technology. The needed properties and the structure of hardphase materials in particular nanopowders, may be obtained using cryochemical technologies. When producing nanopowders by a cryochemical method the most responsible phase is the phase of freezing of a liquidphase system of metal salt - dissolvent (water) using a lowtemperature coolant that predetermine the structure and the properties of a final product. There are different methods of a liquidphase system freezing, the most spreading of which is pulverization into boiling nitrogen. The disadvantages of this method may be overcome using cryogranulation in nonboiling refrigerant. Herewith a number of requirements are made of refrigerants (low temperature coolants). These requirements may be fulfilled using not watersoluble organic liquids (for example geksan). Refrigerating machines refrigerate the coolant up to low temperatures. It is knows that regenerative gas refrigerating machines (GRM) operating on a Stirling cycle at cooling temperatures lower -80 °C are more efficient than the vapor compression ones. Moreover their construction and exploitation are simpler, the servicing is minimal during operating life as well as they begin faster to operate on running conditions. In this connection it is offered to use GRM to refrigerate coolants but it will require additional studies and the establishment of a heat engineering test bench.