2030. The fourth generation refrigerant is marked by alternative working fluids represented by R134a. Its patent protection period is 20 years, calculated from the date of patent application. The fourth generation refrigerant is non-polluting and does not produce a greenhouse effect. It is environmentally friendly, but has low refrigeration efficiency, poor safety, and high production costs. As of December 25, 2023, it is mainly used in the commercial refrigeration market.