Trane TRG-TRC004-EN manual 6OLGH9DOYH, Slide Valve

period two

Compressor Capacity Control

notes

6OLGH￿9DOYH

GLVFKDUJH	KRXVLQJ
SRUW

URWRUV

VOLGH￿YDOYH

Figure 37

Slide Valve

The helical-rotary compressor used as the example in this clinic is unloaded using a slide valve that is an integral part of the compressor housing. Other helical-rotary compressor designs may use a variety of methods to vary capacity. Some of these methods are similar in function to the slide valve presented in this clinic. One major determining factor is whether the compressor is designed to unload in steps, like a reciprocating compressor, or if it has variable unloading.

The position of the slide valve along the rotors controls the volume of refrigerant vapor delivered by the compressor, by varying the amount of rotor length actually used for compression. By changing the position of the slide valve, the compressor is able to unload to exactly match the evaporator load, instead of unloading in steps like the reciprocating compressor discussed earlier.

26 TRG-TRC004-EN