**3. Need of moving towards natural refrigerants**

In early 1970s, scientists come to know about the hazardous impacts contributed to the earth's atmosphere by Chlorofluorocarbons (CFCs). CFCs were widely used as foams, refrigerants and thinners for many industrial applications. UV-B radiation which is passing through the ozone depletion areas from the sun can spread straight to the Earth's surface and will cause distinctive harms in the human cells, plants and animals. And this is because of the ozone layer destruction by CFC's. An international treaty was decided at Montreal, Canada, to ensure further damage of ozone layer. The outcome of Montreal protocol was to begin the phasing-out the usage of CFCs and other Ozone Depleting Substances (ODS) like Hydro chloro fluorocarbons (HCFCs).

Hydro fluoro carbons (HFCs) are considered to be one of the major, fastest growing, and most potent, greenhouse gases. In the past two decades, discharges of hydro fluoro carbons (HFCs) have been increasing swiftly. HFC's are the substitutes for chlorofluorocarbons and hydro chloro fluoro carbons (HCFCs). But stratospheric ozone is not destroyed by HFC's, but they are considered to be one of the effective greenhouse gases with a significant global warming potential (GWP) [1]. Many commercial refrigeration systems, such as beverage coolers, vending machines, ice cream freezers, open deck coolers and freezers used in hypermarkets


## **Table 2.**

*ODP and GWP of popular refrigerants.*

use Hydro chloro fluorocarbons (HCFCs) and Hydro fluoro carbons (HFCs) gases as refrigerants. HCFCs are one of the ozone depleting agents and they have to be phased out as per the Montreal Protocol.

Even though the phasing out of CFC's are a great success in developed countries, there is still a delay in phasing out of HCFC's in the developing countries. There is a need of awareness among the general public about the safe use of fluorinated refrigerants and their adverse effects to our planet earth. Necessary training for the refrigeration and air conditioning technicians in the developing countries as this will ensure the safe recovery of these harmful refrigerants. There is a repeated history prevailing now in the use of natural refrigerants in the air conditioning industry. Because of the climatic changes and associated global warming problems, nowadays natural refrigerants are preferred in place of CFC's. In the present technology in the refrigerant sector, two ozone-friendly refrigerant technologies are available instead of CFC's: 1. Fluorinated refrigerants (HFC's) which are harmful to climate and 2. Natural refrigerants which not harmful to environment. So it is obvious and mandatory to move towards the use of natural refrigerants which have advantages on climate ozone layer. The **Table 2** as shown below present the ODP and GWP of popular refrigerants.
