Which type of compressor uses a damper to control capacity?

The correct choice is centrifugal compressors, which utilize a damper to control capacity through the regulation of airflow. In centrifugal compressors, capacity control is crucial for their operation, especially in varying load conditions. The damper helps manage the amount of air entering the compressor, thus adjusting the output without changing the compressor's speed or efficiency significantly.

In many applications, the ability to modulate capacity allows for more energy-efficient operation, especially in large chillers where demand can fluctuate substantially. By controlling the airflow with a damper, the centrifugal compressor can operate more efficiently under varying conditions, ensuring better performance and energy savings.

Other types of compressors, such as reciprocating, scroll, and screw compressors, typically employ different methods of capacity control. For instance, reciprocating compressors may use variable speed drives or unloaders, and scroll compressors often have a more fixed capacity due to their design. Screw compressors can adjust capacity through variable frequency drives or by unloading stages, but they do not utilize dampers in the way that centrifugal compressors do. Understanding these distinctions is essential for recognizing how different compressors adapt to changing operational demands.