Heat pump water heaters and car air conditioners, are also used as refrigerant in the binary refrigeration cycle of refrigerated showcases. When used as a hot water heater, it is characterized by being extremely high pressure and exceeding the supercritical zone and becoming a transcritical cycle. The reason why the use of CO2 , which needs to be reduced, as a refrigerant, is because it is a natural refrigerant with a LOWER GWP than the other refrigerant overwhelmingly.

Refrigerant number
NameCarbon dioxide
CategoryNatural refrigerant
Molecular structure
GWP1 (carbon dioxide is the benchmark)
Safety classificationNonflammable, non-toxic (A1)