There is a growing focus on a new group of low GWP lower flammable HFCs, none of which are in broad use today. The main members of this group are currently R1234yf, R1234ze and blends between these and non-flammable HFCs. R1234yf, R1234ze are examples of unsaturated HFCs also known as HFOs (hydrofluoroolefin).
The low GWP HFCs are likely to have a significant role in the future, but are typically lower flammable and must be handled according to this.
The HFO R1234yf is a low GWP alternative to R134a with similar pressure but with slightly less volumetric efficiency and cooling capacity. The GWP of R1234yf (4) is much lower than R134a (1430), and this is one of the reasons why it has been selected by most of the car industry as the replacement for R134a in Europe for automotive A/C. R1234yf is an important ingredient in the most promising low-GWP HFC blends.
The HFO R1234ze(E) is a low GWP alternative to R134a with similar pressure but with less volumetric efficiency and cooling capacity. Originally developed for foam blowing the production cost is lower than R1234yf. Along with the high molecular weight this is among the reasons why R1234ze(E) is being considered for replacing R134a in centrifugal chillers for large A/C systems. R1234ze(E) is an important ingredients in future HFC blends just like R1234yf.
Low flammable HFCs must be handled appropriately both with respect to avoiding ignition sources and with respect to relevant standards and legislations. If they are used responsibly, Low flammable HFCs can be employed in a variety of refrigeration and air conditioning applications.
Low flammable HFCs tends to break down relatively fast in the atmosphere. This gives these refrigerants low GWP, and is the primary reason for the increased interest in these fluids.