Research continues to develop solutions to replace high GWP HFC refrigerants, mainly R-404A (GWP 3,922 – Note 1), R-410A (GWP 2,088) and HFC-134a (GWP 1,430), under the F-Gas Regulation provisions regarding HFC phase-down and equipment use restrictions, and recently under the Kigali Amendment to the Montreal Protocol.
R-404A and R-410A are essentially targeted because of their GWP, specifically by the GWP > 2.500 use ban (affecting R-404A) from January 2020 for commercial applications and by the GWP > 750 single split air conditioner use ban from 2025.
HFC-134a has a predominant share of the CO2-equivalent available quota for HFCs. The quantities of HFCs as CO2-equivalent placed on the market will have to be reduced, in order to comply with the F-Gas Regulation mandated phase-down schedule (minus 37 % in 2018 and minus 55 % in 2021), ) and options to replace HFC-134a with lower GWP alternatives would be helpful in meeting the cap.
The main issues to be met in the search of alternative solutions are : suitable thermodynamic properties, capacity to meet systems requirements, energy efficiency, and flammability – however mild – of some products or blends.
Substitutes should preferably be non flammable, but this requirement leads to blends having a GWP in a range of 300 to 1,300 or even more.
Mildly flammable (ASHRAE A2L safety group) substitutes have generally GWPs lower than 300 but their final acceptance will depend on safety standards updates which are expected following the results of the ongoing research on Flammable refrigerants.
A previous News had listed a few following alternatives :
For R-404a (GWP 3,922)- they are all ASHRAE A1 safety group (non flammable, non toxic) :
– R-448A (GWP 1,386)
– R-449A (GWP 1,397)
– R-452A (GWP 2,140) (Note 2)
For R-410a (A1 – GWP 2,088) : R-452B (A2L – GWP=698)
For HFC-134a (GWP 1,430) : R-513A (A1 – GWP=631).
More recently more blends showing promising results have been proposed, such as (the list is not supposed to be comprehensive, as research is still going on) :
For R-404A :
– R-407H (A1 – GWP 1,495)
– R-449A (A1 – GWP 1,397)
– R-449B (A1- GWP 1,412)
– R-454A (A2L – GWP 239)
– R-455A (A2L – GWP 148)
– R-454C (A2L – GWP 148)
– R-457A (A2L – GWP 139)
For R-410A :
– R-447B (A2L – GWP 740)
– R-454B (A2L – GWP 466)
– R-459A (A2L – GWP 460).
For HFC-134a : (A2L blends have not been included)
– R-450A (A1 – GWP 604)
– R-513B (A1 – GWP 596)
The composition of all ASHRAE presently listed blends is given in a recently released factsheet.
Note 1 : GWP values are from the F-Gas Regulation 517 (2014), based on IPCC AR4.
Note 2 : Despite its high GWP of 2,140, R-452A has be retained for transport refrigeration, where the system requirements are particularly hard to meet, and since it represents a perfect drop in to replace R-404 in a large fleet of trucks, trailers, and marine containers.
Source : BITZER – Refrigerant report 19