Natural refrigerants as the substitute for CFC/HFC refrigerants in vapor compression refrigeration units: A review

Most of the vapor compression refrigeration systems in India still continue to utilize chlorofluorocarbon (CFC), hydro-chlorofluorocarbon (HCFC), hydro-fluorocarbon (HFC) based refrigerants, which have the major advantage of thermo-physical properties. CFC and HFC refrigerants have adverse environmental impacts like, the ozone layer depletion (ODP) and global warming (GWP). In order to meet the objectives of the international protocols (Montreal and Tokyo), and also to satisfy the needs of growing demand of these substances for various applications, continuous efforts are going on, around the world to arrive at alternative, eco-friendly refrigerants. Hydrocarbon (HC) based natural refrigerants, like propane (R290), butane (R600), isobutene (R600a), carbon dioxide (R744)) are found to be better replacements for the CFCs and HFCs. An attempt is made here to review the important experimental and theoretical works carried out around the world with these natural refrigerants. In addition, safety and scope of the natural refrigerants are also discussed.