Introduction
Scroll compression principle
In a Danfoss CH scroll compressor, the compression is performed by two scroll elements located in the upper part of
the compressor.
Suction gas enters the compressor at the suction connection. As all of the gas flows around and through the
electrical motor, thus ensuring complete motor cooling in all applications, oil droplets separate and fall into the oil
sump. After exiting the electrical motor, the gas enters the scroll elements where compression takes place.
Ultimately, the discharge gas leaves the compressor at the discharge connection.
The figure below illustrates the entire compression process. The centre of the orbiting scroll (in grey) traces a circular
path around the centre of the fixed scroll (in black). This movement creates symmetrical compression pockets
between the two scroll elements. Low-pressure suction gas is trapped within each crescent-shaped pocket as it gets
formed; continuous motion of the orbiting scroll serves to seal the pocket, which decreases in volume as the pocket
moves towards the center of the scroll set increasing the gas pressure. Maximum compression is achieved once a
pocket reaches the center where the discharge port is located; this stage occurs after three complete orbits.
Compression is a continuous process: the scroll movement is suction, compression and discharge all at the same
time.
© Danfoss | Climate Solutions | 2022.09
AB236986442743en-000501 | 5
Scroll compressors, CH290 and CH485 | Introduction