Which of the following is a style of oil pulling for compressors?

Oil pulling in the context of compressors refers to methods used to maintain the proper lubrication and cooling of the compressor components. Liquid injection is an effective technique that involves injecting a mixture of liquid (often refrigerant oil) into the compressor. This helps to reduce wear, maintain temperature, and ensure that the compressor operates efficiently through effective lubrication.

Thermosiphon systems utilize the natural circulation of liquid based on temperature differences, while water/glycol mixtures are commonly used as coolants in refrigeration systems. This approach not only helps in cooling the compressor but also aids in keeping the oil at optimal viscosity, which is critical for efficient compressor operation.

The other methods mentioned, such as centrifugal separation, multi-stage compression, and heat exchanger methods, serve different purposes in the refrigeration cycle but do not directly pertain to the style of oil pulling. Centrifugal separation is primarily a technique for separating oil from the refrigerant, multi-stage compression is related to compressing refrigerant in steps to achieve higher pressures, and heat exchanger methods involve transferring heat rather than oil pulling specifically.