[Bldg-sim] Fw: Scroll Chiller

[W. Peter Anderson]

----- Original Message ----- 
From: W. Peter Anderson 
To: Bishop, Bill 
Sent: Monday, May 19, 2008 2:48 PM
Subject: Re: [Bldg-sim] Scroll Chiller


Thanks Bill, that is correct.  Scrolls (reciprocating, screw) ARE positive displacment compressors.  

As I was writting I had a sense I typed this incorrectly.  But I knew what I meant and did not read what I wrote.

If anyone cares to learn more, read ASHRAE Handbook Chapter S34 for details.

Regards,
Peter
  ----- Original Message ----- 
  From: Bishop, Bill 
  To: W. Peter Anderson 
  Sent: Monday, May 19, 2008 2:19 PM
  Subject: RE: [Bldg-sim] Scroll Chiller


  Did you mean to say that centrifugal chillers do not have positive displacement compressors?

   

  William Bishop, EIT, LEED® AP | Pathfinder Engineers LLP

  Mechanical Engineer


  3300 Monroe Ave., Suite 306 
  Rochester, NY  14618

  TEL (585) 218-0730 Ext. 114
  FAX (585) 218-0737 

  bbishop at pathfinderengineers.com

   

  www.pathfinderengineers.com

  P Please consider the environment before printing this email


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  From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of W. Peter Anderson
  Sent: Monday, May 19, 2008 1:39 PM
  To: Eric Youngson; bldg-sim at lists.onebuilding.org
  Subject: Re: [Bldg-sim] Scroll Chiller

   

  Not having looked too closely at the options, I would suggest not centrifugal.  

   

  Centrifugals are almost always water cooled, have modulating capabilites from10% to 100% capacity, and generally dont go below 200 tons capacity.  They are positive displacment compressors and will follow the "fan laws", meaning there is a cubic relationship between energy used and cooling capacity (tons).  Similar to a centrifugal pump and fan.

   

  Scrolls are (until the very near future) air cooled and on/off control.  They are staged.  You wont see them over about 150 tons total chiller size.  Part load capacity is pretty constant, in terms of kW/ton.  There are usually multiple stages.  At 50% load, half the compressors (therefore power requirement) is used.

   

  Generally speaking, scroll IPLVs run about 1.1 kW/ton

  water cooled centrifguals operate at around .50 kW/ton.  But cooling towers need to be added, as well as condenser water pumps.  

   

  Lots of variables to consider.  

   

  Hope this was helpful.

   

  W. Peter Anderson, P.E
  JP Engineering
  41 Mechanic Street
  Windsor, CT 06095
  Ph: 860/688-5223
  Fax: 860/688-5269

   

   

    ----- Original Message ----- 

    From: Eric Youngson 

    To: bldg-sim at lists.onebuilding.org 

    Sent: Monday, May 19, 2008 12:47 PM

    Subject: [Bldg-sim] Scroll Chiller

     

    SIM List,

                    I need to model a scroll chiller (. Does anyone have an opinion on which eQUEST chiller is a reasonable choice for this? I was thinking that centrifugal would be the closest but this is simply based on mechanical operation. I would like to choose the closest model based on performance.

     

     


         Eric Youngson 
         
         PAE Consulting Engineers, Inc. 
         
         503.226.2921 Main
          503.542.0567 Direct
          503.226.2930 Fax
          ericy at pae-engineers.com 
         
          Mechanical 
         808 SW Third Avenue - Suite 300
          Portland, OR 97204-2426
          www.pae-engineers.com 
         
          inspire  interpret  integrate 
         







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