Which refrigerant is known for the lowest solubility of oil?

The refrigerant known for having the lowest solubility of oil is carbon dioxide (CO2). In refrigeration systems, the solubility of oil within a refrigerant can significantly affect system efficiency, lubricity, and overall performance. CO2, as a natural refrigerant, exhibits minimal solubility with common lubricating oils used in these systems. This characteristic allows for better separation of the refrigerant and oil, reducing issues such as oil fouling and ensuring consistent lubrication of the compressor.

This lower solubility is advantageous in particular applications, allowing CO2 systems to maintain better performance and efficiency due to reduced oil migration. In contrast, other refrigerants, such as HFC-134a, ammonia, and R-22, typically have higher oil solubility, which can lead to challenges in managing lubrication and overall system operation. Thus, CO2 stands out as an effective choice for applications where low oil solubility is desired.