Solubility and Viscosity of Variably Miscible Mixtures of Refrigerant and Lubricant

Achieving appropriate miscibility, solubility, and working viscosity between a lubricating oil and a refrigerant is vital for proper compressor performance. These properties are all interrelated and cannot be optimized independent of one another; the thermodynamics that define one interaction also influence the others. Choosing the best fluid combination is therefore a tradeoff between the different properties, making it critically important to understand their possible behaviors. This paper will investigate the range of liquid–liquid miscibility behaviors and explore the resulting solubility and working viscosity outcomes. Different lubricant chemistries will be tested to demonstrate the impact of lubricant chemical family on performance, as well as looking within a chemical family to show how finely tuned chemistry choices can shift test results. The outcome from this investigation will help compressor engineers design more reliable and energy-efficient systems.