Abstract: Methods for improving a refrigeration systems comprising modifying the system and replacing existing refrigerant with a replacement refrigerant comprising: (1) at least about 50% by weight of R1234ze(E); (2) greater than 0% to about 11% of HFC-134a, HFC-134, HFC-227ea, HFC-125, and combinations of two or more of these; and (3) from about 4% to about 20% by weight of HFO-1336mzz(E), HFO-1224yd(Z), and combinations of these, wherein said second refrigerant: (i) has an Occupational Exposure Limit (OEL) greater than 400; (ii) is classified as class A1 by ASHRAE Standard 34; and (iii) has a GWP of about 150 or less.

Abstract: Methods for forming an improved, centralized refrigeration systems comprising: (a) providing an existing refrigeration circuit with an existing high GWP refrigerant; (b) disconnecting the fluid connection between the existing liquid refrigerant from the condenser and the evaporators; (c) disconnecting the fluid connection between the existing refrigerant vapor from the evaporators and the compressor suction; (d) establishing a new first refrigeration circuit comprising the compressor and the condenser; (e) establishing a new second refrigeration circuit comprising the evaporators by removing existing refrigerant from the evaporators and the disconnected conduits and replacing the removed refrigerant with a second refrigerant comprising at least 50% of R1234ze(E) and being Class A1 and having an OEL greater than 400 and a GWP of about 150 or less; and thermally interconnecting the new first refrigeration circuit and the new second refrigeration circuit with an inter-circuit heat exchanger.