Final answer:
The type of oil most commonly used in stationary refrigeration applications with HFC-134a refrigerant is polyolester oil. It is compatible with HFC refrigerants and offers the necessary lubrication while being environmentally favorable.
Step-by-step explanation:
Type of Oil for HFC-134a Refrigerant
The type of oil most commonly used in stationary refrigeration applications with HFC-134a refrigerant is polyolester oil (POE). Unlike mineral oil, polyolester oil is compatible with hydrofluorocarbon refrigerants like HFC-134a. Mineral oils were more common with the older chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) refrigerants. With the phase-out of CFCs due to environmental regulations such as the Montreal Protocol, HFCs have become more prevalent. The lubricant needs to be miscible and stable with the refrigerant, and POE oils have been shown to perform well in these systems, providing the necessary lubrication for the moving parts, like compressors, while being less harmful to the environment than traditional mineral oils.