Experimental evaluation and field trial of low global warming potential R404A replacements for commercial refrigeration

R404A refrigerant is widely used for various refrigeration applications ranging from centralized refrigeration systems for supermarkets to transport refrigeration for truck/trailer. Various environmental regulations have been proposed in the United States and Europe that phase out the use of high global warming potential refrigerants like R404A (global warming potential = 3943) in these applications. This article presents an evaluation of two low global warming potential R404A replacements: A nonflammable refrigerant R448A with global warming potential of 1273 and a mildly flammable refrigerant R455A with global warming potential of 146. Tests carried out with a commercially available R404A self-contained freezer showed that the compressor run time of R448A and R455A are similar to R404A due to similar capacity. The 24-h energy consumption of the compressor is 9% lower for R448A and 6% lower for R455A compared to R404A. Tests were also performed with R448A in a commercially available walk-in freezer/cooler. R448A matches the capacity with 4 to 8% higher efficiency compared to R404A. This indicates that R448A and R455A can reduce both the direct and indirect emissions significantly in these systems. Finally, this study presents the performance results conversion of an actual supermarket refrigeration system from R404A to R448A, which resulted in energy savings from about 9 to 20% depending on outdoor ambient temperature.