A tribological study of refrigeration oils under HFC-134a environment

• Published in: Tribology international Vol. 30; no. 9; pp. 707 - 716
• Main Authors: Chul Na, Byung, Jin Chun, Keyoung, Han, Dong-Chul
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1997; Elsevier
• Subjects: alternative refrigerant; Applied sciences; boundary lubrication; close type wear tester; Energy; Energy. Thermal use of fuels; Exact sciences and technology; friction; Friction, wear, lubrication; Machine components; Mechanical engineering. Machine design; Refrigerants; Refrigerating engineering; Refrigerating engineering. Cryogenics. Food conservation; refrigeration oil; wear profile; refrigeration oil; close type wear tester; alternative refrigerant; boundary lubrication; friction; wear profile; Lubricating oil; Ester; Wear test; Miscibility; Olefin oxide polymer; Friction test; Boundary lubrication; Material compatibility; Experimental study; Refrigerant fluid; Tribology
• ISSN: 0301-679X; 1879-2464
• DOI: 10.1016/S0301-679X(97)00072-8

HFC-134a is a potential alternative material for CFC-12, which depletes the ozone layer. However, problems arise when used together with conventional refrigeration oils due to the extreme polarities of HFC-134a. PAG (polyalkylene glycol) and esters are tested with HFC-134a. This investigation enhances the testing method by taking the compressor's environment into account. Miscibility and material compatibility are proved with sealed glass tests. A testing environment charged with refrigerant gas more closely simulates the conditions of a compressor. The conventional refrigeration oils (mineral oils, alkylbenzene, PAO (polyalpha olefin)) tested here are immiscible with HFC-134a. However the PAG and ester oils are miscible with HFC-134a. The friction coefficient of the PAG/HFC-134a system is similar to that of the mineral oil/CFC-12 system at operating conditions. Ester oils are preferable at the start and stop condition in the lubricity aspect. PAG shows good lubricity in conditions of extreme contact pressure. Consequently, this test provides reliable results on compressor lubricity and material compatibility of refrigeration oils with HFC-134a. It suggests a methodological way for the proper selection of refrigeration oils that may improve the durability and performance of a compressor.