An American study tries to identify the best candidates to replace HFC refrigerants in air conditioning.

27 suitably-efficient fluids were found to replace HFCs in air-conditioning systems. However, they all are at least slightly flammable.
The current context of the HFC's phase down involved by the ratification of the Kigali amendment implies the search for replacement fluids. A multiyear study focused on refrigerants used in air conditioning systems was therefore conducted by a team of researchers from the US National Institute of Standards and Technology (NIST).

A comprehensive chemical database, PubChem,  was screened to find low-GWP fluids among 60 million chemical structures. The researchers team searched for fluids by applying thermodynamic and environmental screening. According to them, "only a few pure fluids possess the combination of chemical, environmental, thermodynamic and safety properties necessary for a refrigerant and [...] these fluids are at least slightly flammable." These screens actually yielded a set of 27 low-GWP fluids.

They are listed in this table:

The results of the study were recently published in a Nature Communications article, also available on Fridoc.