Why do screw-type compressors exhibit high volumetric efficiency?

Screw-type compressors exhibit high volumetric efficiency primarily due to the design that prevents the re-expansion of refrigerant in the clearance space. In these compressors, the compression process takes place in a continuous manner as refrigerant is drawn into the rotors, and the compactness of the design minimizes the volume where refrigerant can escape and not contribute to the compression cycle.

In other types of compressors, such as reciprocating compressors, there can be a significant amount of clearance volume where refrigerant can remain after the compression cycle, leading to inefficiencies such as re-expansion. In screw compressors, the efficient sealing between rotors and the design minimizes this effect, ensuring that more of the compressed refrigerant contributes to the discharge rather than being wasted.

Consequently, the design characteristics that minimize re-expansion allow screw compressors to achieve higher volumetric efficiency compared to other compressor types, making them suitable for a range of applications, particularly in larger systems where efficiency is critical.