Hydrofluoroolefin (HFO) and Hydrocarbon (HC) refrigerants are referred to as fourth-generation refrigerants for the 21st century following chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs).
HFO refrigerants are actually unsaturated HFC refrigerants and are widely recognized as the next generation of refrigerants because of their environmental friendliness, cost-effectiveness, and great energy efficiencies.