The gas used in a freezer (and also in refrigerators) is called a refrigerant. Over the years, different refrigerants have been used in cooling systems. Historically, chlorofluorocarbons (CFCs) were commonly used as refrigerants, but they were found to contribute to ozone depletion and were subsequently phased out due to environmental concerns.
Currently, one of the most commonly used refrigerants in freezers and refrigerators is hydrofluorocarbon (HFC). HFCs, such as R-134a (1,1,1,2-tetrafluoroethane), have a lower impact on the ozone layer compared to CFCs but still have a relatively high global warming potential (GWP). As environmental concerns have increased, efforts have been made to find more environmentally friendly alternatives.
One of the more environmentally friendly refrigerants used today is hydrofluoroolefin (HFO), such as R-1234yf. HFOs have a significantly lower GWP than HFCs, making them more environmentally friendly choices.
It's important to note that regulations and best practices for refrigerants may vary by region, and ongoing research and innovation are continually leading to the development of even more eco-friendly refrigerant options. The ultimate goal is to reduce the environmental impact of refrigeration systems while maintaining efficient cooling performance.