What is the primary function of a screw compressor?

• A. To utilize the action of rotating blades
• B. To pressurize refrigerant vapor using two synchronized screws
• C. To cool the air using liquid refrigerant
• D. To measure energy efficiency ratios

Answer: (B)

The primary function of a screw compressor is to pressurize refrigerant vapor using two synchronized screws. In this type of compressor, the refrigerant is drawn into the compressor chamber where it is trapped between two helical rotors (the screws). As the rotors turn, the volume of space containing the refrigerant decreases, which increases the pressure of the vapor. This design allows for continuous and efficient operation, making it especially suitable for applications requiring substantial capacity and high reliability.

In contrast, utilizing the action of rotating blades pertains more to centrifugal compressors, which work differently than screw compressors. The cooling of air using liquid refrigerant relates to the system's evaporators or condensers, not the compressor itself. Lastly, measuring energy efficiency ratios is more associated with the performance evaluation of the entire HVAC system rather than a specific function of the compressor alone.