[Equest-users] Free cooling for air-cooled chillers

Joe Fleming joe at thespinnakergroupinc.com
Thu Apr 7 17:47:32 PDT 2011


I have modeled it as follows, (I don't think I dropped the ball);  Set up a
water cooled chiller and set the chiller type to "water-side" economizer.
This will essentially model a cooling tower that pumps chilled water into
the building when the outdoor conditions permit (low wet bulb for the
tower).  Make sure to set the "approach" of the tower to something that
matches your air cooled chiller performance and do the same for the tower
range and fan power.  

Run a couple of iterations to see if the chilled water pumps are used.  If
they are then set the pumping power to a very small number, since you want
your condenser water pumps in the model to be your chilled water pumps in
the design.

Attach this chiller and cooling tower to the chilled water loop with the
other large chillers, with the proper design capacities.  

It should cycle on in the order that it was created, not sure if the free
cooling chiller will take precedence in the cycling (it's been a while),
maybe someone else can help here.  If you want to change the sequencing to
match the design that is another subject and it can be handled in the loop
controls under "Equipment Controls".

 

Let us know how it turns out.

 

 

Joe Fleming, E.I., LEED AP BD+C, BEMP

Commissioning Agent

561-602-3132

 

The Spinnaker Group

www.thespinnakergroupinc.com

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Neil Patel
Sent: Thursday, April 07, 2011 6:12 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Free cooling for air-cooled chillers

 

I'm modeling a building that wants to use modular air-cooled chillers.  So
in addition to several modular chillers, they want to install a few 'Free
Cooling' units.  These units will be tied in with the regular chillers and
will be able to provide free cooling during the winter whenever the outdoor
temperature drops below the mid 30s.  To my understanding, this works when
the ambient temperature is low enough, the return glycol is sent through
economizer coils before it enters the evaporator.  With colder temps, the
refrigeration compressors unload until they are no longer required, and the
full cooling capacity is provided by the condenser-fan alone.  

 

I was wondering if anyone has had any experience with these types of
chillers and what are some of the ways to model this 'free cooling.'  

 

Thanks in advanced for all the help,

 

 

 

 

Neil Patel, EIT, LEED AP BD+C

 

Logo 2

EME Group | Consulting Engineers, LLC

159 West 25th Street, 5th Floor

New York, NY 10001

Tel: 212-529-5969

Fax: 212-529-6023 

www.emegroup.com

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110407/8ec6ff59/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/jpeg
Size: 1822 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20110407/8ec6ff59/attachment-0002.jpeg>


More information about the Equest-users mailing list