Miscibility between refrigerants and lubricants has long been considered essential to the refrigeration cycle. Many compounds that have been proposed for use as lubricants for hydrofluorocarbons (HFC) have polar molecular structures in order to be fully miscible with the refrigerants. However, it seems difficult for these lubricants to maintain long term durability in rotary compressors when R-407C is used.
In order to overcome the durability problem, a new type of lubricant has been developed that sacrifices some of its miscibility in return for better anti-wear properties.
This paper presents new methods for selecting the best lubricant for future air conditioning applications.