Alkylbenzene (AB) oil is miscible in HCFC refrigerants.

• A. True
• B. False
• C. Not sure
• D. Only with CFC

Answer: (A)

In HCFC systems, Alkylbenzene oil acts as a hydrocarbon-based synthetic lubricant that dissolves in the refrigerant rather than forming separate layers. This miscibility means the oil and the refrigerant mix into a single phase over the typical operating temperature and pressure range, which helps the oil circulate with the refrigerant and return to the compressor, ensuring proper lubrication. The interaction is favored by the nonpolar hydrocarbon structure of AB oil, which blends well with HCFC molecules like R-22. Keep in mind that this favorable miscibility is specific to HCFCs; many HFC refrigerants (like R-134a) behave differently and may require different oils. Given the HCFC context, the statement is true.