Which type of compressor does not require lubrication?

The correct answer is centrifugal compressors, which typically do not require lubrication in the same manner as other compressor types. This is primarily because they use a different mechanism for compressing refrigerant. In centrifugal compressors, the refrigerant is moved using an impeller that generates centrifugal force, allowing for a continuous flow of the refrigerant through the compressor without the need for direct lubrication on moving parts.

Unlike reciprocating compressors, which rely on pistons and require lubrication to minimize friction and wear, centrifugal compressors are designed to operate with minimal friction, as their design allows for smooth movement of refrigerant. This efficiency in operation reduces the need for additional lubrication, helping to maintain the integrity of the system and reducing maintenance requirements.

Scroll and rotary compressors, while different in their mechanics, still require lubrication to function effectively and prevent wear on their internal components. They rely on moving elements, which necessitate a lubricant to ensure smooth operation and longevity. The unique characteristics of centrifugal compressors highlight their efficiency and maintenance benefits compared to traditional mechanical designs that require lubrication.