CARBON DIOXIDE UTILIZATION FEATURES AS VAPOR-COMPRESSION REFRIGERATING MACHINE WORKING SUBSTANCE. EFFECTIVE CYCLES AND EXPERIENCE OF INTRODUCTION IN THE NATIONAL ECONOMY

As working substances of the vapor-compression refrigerators (VCR) it is possible to use various substances. These are specially synthesized mixtures ? freons, and natural coolants ? ammonia, carbon dioxide, hydrocarbons. VCR cycles suitable for operation on carbon dioxide (R744) are analyzed in the paper. Subcritical, transcritical, throttle, detander and cascade cycles in which carbon dioxide is applied as a coolant of the low temperature contour are considered. Comparison of throttle cycles with various cooling temperature characteristics, one - and two-level compression is given. The short history of the refrigeration units working at CO2 introduction is presented, the list of the producers manufacturing the equipment taking into account features of the studied working substance is provided. Advantages of the cooling systems working at carbon dioxide on the basis of their operation experience in various European countries are shown.