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

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period two

Compressor Capacity Control

notes

6OLGH9DOYH

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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

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Contents Air Conditioning Clinic Refrigeration Compressors Business Reply Mail One of the Fundamental Series Comment CardRefrigeration Compressors 5HIULJHUDWLRQ&RPSUHVVRUV PrefaceContents TRG-TRC004-EN 9DSRU&RPSUHVVLRQ5HIULJHUDWLRQ Introduction5HIULJHUDWLRQ&\FOH RPSUHVVRU7\SHV Compressor TypesReciprocating Compressor 5HFLSURFDWLQJ&RPSUHVVRUFrpsuhvvlrq Vwurnh Rshqlqj Glvfkdujh Slvwrq Scroll Compressor 6FUROO&RPSUHVVRUMrxuqdo Lqwdnh Skdvh Frpsuhvvlrq Glvfkdujh Helical-Rotary Screw Compressor +HOLFDO5RWDU\6FUHZ&RPSUHVVRU+HOLFDO5RWDU\&RPSUHVVRU Phvklqjsrlqw Centrifugal Compressor HQWULIXJDO&RPSUHVVRUYroxwh Gliixvhu Sdvvdjhv Udgldo Lpshoohu Eodghv Uhiuljhudqw 2SHQ&RPSUHVVRU 6HPLKHUPHWLF&RPSUHVVRU +HUPHWLF&RPSUHVVRU0HWKRGVRI&RPSUHVVRU8QORDGLQJ Compressor Capacity ControlCylinder Unloaders \OLQGHU8QORDGHUVXqordghufrqwuroohu Vrohqrlgydoyh Ydoyh DSDFLW\9HUVXV6XFWLRQ7HPSHUDWXUH RPSUHVVRU8QORDGLQJ $OWHUQDWLQJ&\OLQGHUV2QDQG2II \FOLQJ2QDQG2II \FOLQJ6FUROO&RPSUHVVRUVCycling On and Off \FOLQJ6FUROO&RPSUHVVRUV Slide Valve 6OLGH9DOYHInlet Vanes QOHW9DQHVInlet vanes presented in this section of the clinic Variable Speed 9DULDEOH6SHHGCompressor in a System \VWHP/HYHO&RQWUROSystem-Level Control RQVWDQW9ROXPH6\VWHP KLOOHGDWHU6\VWHP 9DULDEOH$LU9ROXPH6\VWHPPreventing Evaporator Freeze-Up 6HQVLQJ6XFWLRQ7HPSHUDWXUH +RW*DV%\SDVVWRYDSRUDWRU,QOHW +RW*DV%\SDVVWR6XFWLRQ/LQH System Components clinic 5HYLHZ²3HULRG2QH Review5HYLHZ²3HULRG7ZR \VWHPOHYHOFRQWURO 5HYLHZ²3HULRG7KUHHFor more information, refer to the following references TRG-TRC004-EN Questions for Period QuizAnswers Glossary Glossary Glossary Trane Company