In which refrigerant is the solubility of oil lowest?

The solubility of oil in refrigerants plays an important role in the efficiency and reliability of refrigeration systems. In the case of CO2 as a refrigerant, it is known for having a very low solubility of oil compared to other refrigerants such as R-22, R-12, and NH2.

Low solubility is beneficial because it minimizes issues related to oil return in the system, ensuring that the lubricant remains effective in the compressor while avoiding potential clogging in the system. This characteristic of CO2 allows for better oil management and performance in refrigeration and heat pump applications.

In contrast, the other refrigerants mentioned tend to have higher solubility levels for oil, which can lead to complications such as inefficient lubrication and the formation of oil accumulation in critical areas of the system, impacting overall efficiency and lifespan.