Replacement of Chlorofluorocarbons (CFCs) By Natural Refrigerants

Chlorofluorocarbons (CFCs) have been the subject of worldwide attention due to the stratospheric ozone issue leading to the historic Montreal Protocol, an international agree­ment on control measures for ozone protection. The ozone layer in the stratosphere, which protects life on earth from the sun’s harmful ultraviolet radiation, is getting depleted due to use CFCs and other harmful substances in most of the conventional refrigeration systems. The problem threatens not only human beings, but also the plant and animal kingdom on earth’s surface. In view of this alarming problem, replacements of CFCs by eco-friendly refrigerants becomes an urgent necessity. Carbon dioxide, the old refrigerant in its new form, appears to be a viable alternative refrigerant for the future in the context of CFC phase-out and waste gas utilization. This paper is a state of the art report concerning the various possible alternative refrig­eration cycles based on carbondioxide as a natural refrigerant and the current understanding of the role of this refrigerant in environmental protection.