Identifying lubricant options for natural refrigerants.

Natural refrigerants typically carry properties attractive to providing minimal impact on the atmospheric environment. These advantages can be ultimately lost if the operating system performs poorly resulting in increased power consumption or is unreliable. When it comes to the task of optimizing lubricants for natural refrigerants, in order to provide the best performance, the concepts and approaches taken are no different than those used in synthetic refrigerant investigations. Proper knowledge of lubricant and working fluid interaction in addition to an understanding of system design and operation are keys to making the correct choices. This paper will highlight techniques needed to adequately provide lubricant options for a variety of natural refrigerants and how these techniques have been used to identify suitable lubricant candidates. Focus will be placed on identifying lubricants for hydrocarbons, carbon dioxide and ammonia working fluid options used in a variety of commercial applications today and potential future applications.