Summary

Environmental concern along with re strictions imposed by regulatory agencies have stimulated the use of na tural fluids in cooling systems as an alternative to synthetic refrigerants, namely, CFC HCFC and HFC currently in use. As one of the options, carbon dioxide (CO 2 , R-744) stands out as a promising candidate due to its favorabl e physical properties, safety aspects and environmentally friendly charac teristics. Cooling systems using CO 2 as refrigerant have certain characteristic s which distinguish them from systems that use conventional fluids. In order for these systems to become technically, environmentally and economically feas ible alternatives, their cost and performance must be compatible with the requirements of current systems. Therefore, understanding the peculiarities of CO 2 application and its effects on the overall operation of such systems is vital.

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