Trane TRG-TRC004-EN manual 9DULDEOH$LU9ROXPH6\VWHP, KLOOHGDWHU6\VWHP

Page 39

period three

The Compressor in a System

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Figure 45

As mentioned previously, a VAV system varies the quantity of air supplied to the space in order to satisfy the load. The supply temperature is held constant in this system.

In a VAV DX system, the capacity of the compressor is controlled by sensing the temperature of the air being supplied to the system. The compressor is loaded or unloaded based on how close the actual supply air temperature is to the set point.

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In contrast to the DX system examples shown previously, a chilled-water system responds to changing space loads by controlling the capacity of the chilled-water cooling coil. Although there are various methods of controlling the capacity of this coil, this discussion will assume the use of a modulating water valve.

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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