الفهرس 
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Abstract
In last few decades significant attention has been given to the research for alternative refrigerants, which have ODP and GWP leading eventually and inevitably to the so-called “natural refrigerants”. These are, by definition, substances which have no adverse effects on the ecological balance of our planet and are part of the natural environment. Such substances which are practically available today are ammonia, hydrocarbons, air, carbon dioxide and water. Water has high specific heat and latent heat of vaporization about 2500 [kJ / kg], which is 10 times higher than of refrigerant R22. Water - clean stuff, do not deplete the ozone layer (ODP = 0) and do not contribute to global warming (GWP = 1 that is 1300 times less than the R134). Chemical stability, explosion and fire safety and full compatibility with the environment are the unique qualities that offer great opportunities for the use of water as the working substance in refrigeration. Application of water in refrigeration system is limited by its high freezing point, which does not provide a temperature below 0 °C. This disadvantage is eliminated by the possibility of using water-salt solutions, as well as organic liquids - alcohols, ethers and their mixtures with each other and with water. Estimations show that the vacuum-evaporation unit with the suitable working fluid can be used successfully in the temperature level of -10 ……....- 30 ° C Vacuum-process technology for cooling liquids needs no refrigerant of the conventional kind, but water from the process itself is used to generate cooling. The use of water as a Refrigerant (R718) in refrigeration systems is an environmental friendly new technology suggested and successfully installed over the recent years. It is easily available and there are no problems disposing it after use. In vacuum refrigeration machines, water may be as a refrigerant and coolant simultaneously, which lowers costs and makes the refrigeration system simpler. The purpose of the present study is obtaining the experimental characteristics and analytical description of vacuum cooling process of water to near-zero temperatures by creating ice-water composition of alternating layers of ice and water with calculation of the loss of their mass.