[Bldg-sim] VSD Chiller Curves

[Steven Gates]

It's the differential between the entering condenser water temperature and
the leaving chilled water temperature.

 

Savings for chillers with VFDs are dependent on the pressure rise the
impellor must overcome.  Maximum savings accrue if the dT is low when the
load is low.  If the cooling tower is running warm when the load is low,
then the impellor may have to run at close to full speed to produce the
required pressure rise and avoid surge.  The dT term takes that effect into
account.

 

 

  _____  

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of David S
Eldridge
Sent: Tuesday, April 01, 2008 2:12 PM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] VSD Chiller Curves

 

http://doe2.com/download/DOE-22/DOE22Vol6-NewFeatures_44e2.pdf, printed page
74 (PDF page 79).

 

 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Chien Si
Harriman
Sent: Tuesday, April 01, 2008 3:17 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] VSD Chiller Curves

 

Hi there-

 

Curious if anyone out there knows anything about the chiller EIR-fPLR curve
that is inserted by default in eQuest, when a user selects a variable
frequency drive compressor?  Most of the time, the EIR-fPLR curve is a
quadratic curve based only on the PLR, but this curve is biquadratic, with
another term called dt.  Can anyone enlighten me on which dt they are
talking about here?  I can't find it in the documentation.

 

Sincerely,

 

 


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Chien Si Harriman 
West Coast Technical Manager 

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