A type of HFC, HFC32 has the potential to significantly reduce global warming: it has a global warming potential approximately one-third of HFC410A, and it is more efficient. It can be adapted for use in air conditioners in a relatively short time, and it is an economical way to contribute to reducing global warming impact. It is slightly flammable.
HFO1234yf
Hydrofluoroolefin. A refrigerant newly developed for use in car engines. Because it has about the same effect on global warming as natural refrigerants, it is slated for use as a next-generation car engine air conditioner. Research is underway to solve several issues that prevent HFO1234yf from being used in general air conditioners; it still contributes to global warming due to its low efficiency and its high power consumption. It is slightly flammable.
Carbon dioxide (CO2)
CO2 has a lower toxicity rating and is not flammable. Because it has similar performance as conventional refrigerants for applications like water heaters, Daikin uses CO2 as a refrigerant for heat pump water heaters. However, because it has a low COP, air conditioners using it require more electricity, thus, there are doubts whether it will lessen the total global warming impact.
Propane
Propane has equivalent performance to R22, and isobutane, a substance similar to propane, is used as a refrigerant in refrigerators. However, there are still many issues in using propane as a refrigerant in air conditioners. It is highly combustible and thus susceptible to explosion in the event of leakage into the air. To use as an air conditioner refrigerant, the volume of propane must be dramatically reduced to ensure that it is safe. As well, the pipe work for air conditioners must be done on-site. Current technology cannot guarantee the safety of propane air conditioners.
(by Daikin Industries, Ltd.)