A review of lubrication and performance issues in refrigeration systems using a HFC (R-134a) refrigerant

It has been considered critical for refrigerant and compressor lubricants to be miscible with each other over part of the range of operating conditions of refrigerant systems. Adequate miscibility, many believe, provides oil return to the compressor. Presently, synthetic polyol esters have been selected for use with HFC refrigerants, such as R-134a, which are considered appropriate alternatives to CFCs. The authors will review the mechanical issues in miscible vs. non-miscible naphthenic hydrocarbon oil-based lubricants. Extensive lab, test stand and cabinet testing has been conducted and data will be presented which show reasonable and predictable performance based on the chemical and physical properties of the lubricant and refrigerant. Many non-miscible systems show satisfactory performance with the proper selection of lubricant, additives and mechanical configuration.