Evaluating Lubricants For Lower GWP Refrigerant Compressor Operations

Refrigerant Lubricants are an essential component to refrigerant and air conditioning compressor operation regardless of the refrigerant used. But to maintain reliable and efficient operation, the choice of lubricant can vary depending on the type of compressor, design of the system and especially the kind of refrigerant. Historically, refrigerants used in applications have changed over the period of time since the invention of refrigeration due to various reasons. Today the global warming potential (GWP) value that exists for each refrigerant are being scrutinized if the GWP value is deemed too high which could result in a negative environmental impact. One of the so called high GWP refrigerants is R-404A which is on the fast track to be minimized through regional and global phase downs and potential phase outs. Various replacement/substitute refrigerants exist today that have been evaluated or are currently being evaluated as lower GWP choices in place of R-404A refrigerant. For R-404A the typical lubricant of choice has been a synthetic lubricant such as a polyolester (POE) which meets certain criteria for refrigerant and lubricant interaction. Replacement/substitute lower GWP refrigerants for R-404A will vary in the type of lubricant chemistry that is satisfactory for effective operation resulting in numerous lubricant selections.   This paper will evaluate lower GWP refrigerant options and what lubricant chemistry is best suited. Various rules that apply to what testing is needed to make the appropriate conclusions will be outlined and results of refrigerant and lubricant interaction will be presented. This data will then be used to determine how the changes in lower GWP refrigerant properties will dictate these lubricant options. This type of information will allow for maintaining the required compressor performance parameters associated with the industry