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ESIE10-01 General Outline

Part 1 – System Outline 1–101

Compression

process

With the single-screw compressor, the suction, compression and discharge process takes place in a

continuous manner thanks to the two satellites. In this process, the suction gas penetrates into the

profile between the rotor, teeth of the upper satellite and the compressor body. The volume is gradually

reduced by compression of the refrigerant. The compressed gas under high pressure is thus

discharged into the built-in oil separator. In the oil separator, the gas/oil mixture separates and the oil

is collected in a cavity in the lower part of the compressor, where it is injected into the compressor

mechanisms in order to guarantee compression sealing and lubrication of the ball bearings.

Q STAGE 1-2 SUCTION

During screw rotation, the main rotor flutes communicate with the suction chamber, where they

begin suction without compressing the gas mixture. As it rotates, the main rotor increases the

effective length of the free flute, thereby increasing the volume open to the suction. This fills the

flute up to its closing towards the suction chamber by means of the satellite teeth, which gears

onto the screw. Once the gas is closed into the flute and the suction chamber is separated, the

suction stage is complete.

Q STAGE 3 COMPRESSION

As the main rotor turns, the volume of gas trapped within the screw flute is reduced by the satellite

teeth that gear onto the screw, thereby reducing the volume available to the gas mixture. This

entails compression mixture to its maximum value.

Q STAGE 4-5 DISCHARGE

As the satellite tooth approaches the end of the flute, the pressure of the trapped vapour reaches

a maximum value occurring near the triangular aperture of the discharge port. Compression

immediately ceases and the gas is delivered into the discharge manifold. The satellite tooth con-

tinues to push the vapour until the flute volume reaches a minimum value.

This compression process is repeated for each screw flute at each turn.

Refrigeration

capacity control

The compressors are set up as standard with an infinite control of their capacity. Two shutters reduce

reduce suction capacity, delaying flute closing and decreasing its effective length. These shutters are

used to allow the compressor to operate at minimum and maximum loads. The shutters are controlled

by the pressure of the oil from the separator or drained towards compressor suction. A spring helps

create the force necessary to move the shutter. The compressors for the EWAD-C- series use two

shutters for both load and discharge, controlled by the oil-gas flow through the circuits and directly

controlled by the controller through the solenoid valves that are normally closed (NC). The first shutter

allows you to change both the load and discharge continuously. The second, on the other hand, has

the on/off operation. Both individually guarantee a 50% change in load/discharge.

STAGE 1: Initial suction STAGE 2: Suction end

STAGE 4: Discharge start STAGE 5: Discharge end

STAGE 3: Compression