Formerly known as DR-3, and now to be marketed as XL20, the new refrigerant is a blend of R1234yf (78.5%) and R32 (21.5%). Its GWP of 148, based on IPCC 4, brings it just below the 150 limit demanded by the European F-gas regulations for commercial hermetically sealed systems from January 1, 2022. It has been submitted for ASHRAE approval and provisionally assigned the number R454C.
The HFO R1234yf provides the low GWP element of the blend with the R32 being added to increase its cooling capacity and provide a performance close to R404A. Though XL20 is a “mildly flammable” A2L, Chemours maintains that the small charge sizes found in single condensing unit systems and stand-alone coolers and freezers are able to accommodate refrigerants with some degree of flammability.
XL20 is said to exhibit slightly lower pressures and capacity than R404A, but the thermodynamic cycle efficiency is 7% higher than R404A. It does, however, have a moderate 5K temperature glide. Compressor discharge temperatures are also about 12K higher than R404A, but well below temperatures which would normally require liquid or vapour injection.
The results of tests on the new gas as a drop-in on a freezer originally designed to use R404A are to be presented at this summer’s International Refrigeration and Air Conditioning Conference at Purdue University, Indiana.
The drop-in performance of XL20 was evaluated in a 1.5m³ capacity double-door reach-in freezer originally designed for R404A and with a with a refrigerant charge of 1.05kg. The only change made to the system was an adjustment of the TXV.
The 16th International Refrigeration and Air Conditioning Conference takes place at Purdue University, West Lafayette, Indiana, from July 11-14. Further information on the Purdue conference can be found here.