Air conditioning: which refrigerant will become the leading alternative to R410A?
R32 refrigerant is now being adopted on a huge scale by manufacturers for residential and small commercial applications as a replacement for R410A, which has a GWP of 2088.
R32 is classified as A2L, indicating that it is mildly flammable. However, for larger capacity systems, there is a limitation regarding the use of R32, notably when used in variable refrigerant flow (VRF) systems. Even though Daikin and Mitsubishi Electric have developed prototype models, few large-scale air-conditioning units using R32 have been launched on the market1.
GWP of R32 (675) is within the GWP upper limit of 750 imposed by Japan for residential and light commercial air conditioners. However, R32 GWP is higher than the average target GWP of 400 involved by EU F-gas Regulation (517/2014) by 2030*, which indicates that R32 could be considered as a medium-term solution for a period of 10 to 15 years.
Several refrigerant alternatives to replace leading air-conditioner refrigerant R410A were announced last year.
In June 2018, Honeywell unveiled R466A, a non-flammable and non-toxic (A1) refrigerant with a GWP of 733. Its ASHRAE approval process is still ongoing.
Toshiba Carrier, which announced test results of R466A in a VRF system, concluded that it was a promising alternative to R410A. It can be handled in the same way as R410A and does not require the safety devices to mitigate flammability risk normally required for other A3 (flammable refrigerants) or A2L (mildly flammable) alternatives used in air conditioning. R466A’s discharge temperature is higher than R410A’s due to its thermodynamic properties, but not as high as R32’s. Other performances (volumetric capacity, theoretical COP) are similar to R410A’s.
R466A is composed of R32, R125 and CF3I. CF3I – a fire suppressant also known as trifluoroiodomethane –gives the refrigerant its lower GWP of just 733 and ensures its non-flammability. However, CF3I is not without critics. Previous research has raised stability issues1. In an interview in April 2019 by JARN1, G. Koutsaftes, Honeywell Advanced Materials’ President, specified that R466A has been extensively tested in different applications and confirmed it was compatible with the equipment life, that can be greater than 20 years.
In October 2018, Honeywell announced the commercial availability of R452B, a mildly flammable R32/R125/R1234yf blend with a GWP of 676, which is also offered by Chemours. Honeywell’s representative also specified to JARN that R452B was introduced as a R410A replacement for small charge applications than can tolerate the use of an A2L. R452B performance is very similar to R410A’s, with a discharge temperature that is lower than R32, which enhances compressor life2.
For its part, Chemours recommends R454B as an alternative to R410A. R454B is a R32/R1234yf blend with a GWP of 466, which can be used as a near drop-in alternative in new equipment. According to Chemours, R454B properties very closely match those of R410A, and in some cases demonstrate better capacity and efficiency than R410A. R454B, which is mildly flammable but is said to have lower flammability properties than R322, can be used safely in much larger charges than other flammable refrigerants when following the applicable standards and guidelines.
Chemours is also promoting its non-flammable RHFO-based R463A, that can replace R410A in refrigeration equipment, chillers and air-conditioning applications. It has a GWP of 1377 and its properties and performance are comparable to R410A.
Finally, Daikin – which was the pioneer in introducing R32 as a lower GWP replacement for R410A –announced in mid-May 2019 that the company was employing Artificial Intelligence technology to develop a new refrigerant with a GWP of 10 or less. This, they hope, would be introduced in 2023 to replace R32 in air conditioners. Predicting that it would be a “ground-breaking” refrigerant, they indicated, however, that like R32, it would be a “mildly flammable” A2L3.
Currently, in Japan, R32 is becoming the mainstream refrigerant used in room and packaged air conditioners. In Europe as well, R32 air conditioners are becoming more common, but in the small chiller segment, products using R452B and R454B have also been announced. Chinese air conditioner manufacturer Midea has released air conditioners using R452B in the US market, and Johnson Controls has announced a chiller using R454B. Carrier has adopted R454B in ducted residential and light commercial air conditioners sold in North America. Furthermore, the industry is closely watching developments regarding promising non-flammable R466A, to be put on the market soon.
As of today, nothing is yet certain regarding the refrigerant or refrigerants which will replace R410A in the long term.
* The European Commission considers that the HFC phase down required by the EU F-gas Regulation (517/2014) means that the average GWP of HFCs should fall to about 400 by 2030 across all sectors.
1 JARN, April 25, 2019