Centrifugal Compressor

•  single stage 1 impeller

•  multi stage 2 or more impellers

• can operate in vacuum

Operation of Economizer

•  Economizer is a two stage storage for liquid refrigerant takes flash gas vapor back to compressor

•  Reduces flash gas by having a two stage pressure drop through float suction

Purpose of Purge Unit

•  removes non-condensable gases from system (operates in vacuum)

•  part of centrifugal system

Capacity control

Variable inlet vanes, butterfly damper, speed control