R-404A, XL20, XL40, GWP, hydrofluoroolefin
Global pressures on hydrofluorocarbon (HFC) refrigerants have reached new levels. With ongoing country ratifications of the Kigali Amendment to the Montreal Protocol and refrigerant shortages across Europe driven by the F-Gas regulations, equipment manufacturers are working hard to implement lower global warming potential (GWP) solutions. R-404A is one of the higher GWP refrigerants (GWP100 Year = 3,922, per AR4) used widely in commercial refrigeration. Several very low GWP (LGWP) candidates have emerged as potential replacements. For many hermetic and split system applications, hydrofluoroolefin-based (HFO) blends represent lower flammability alternatives to hydrocarbon (HC) refrigerants, that also allow for significantly larger charge sizes. Two mildly flammable, very LGWP blends, XL40 (R-454A) and XL20 (R-454C) were tested and compared to the R-404A baseline performance of a commercially available, double-door, upright reach-in freezer via soft-optimization testing. Refrigerant compatibility with lubricants and other system materials was also examined. Miscibility, water solubility, and dielectric properties were also characterized.