[Equest-users] Free cooling Chiller on eQuest

Neil Bulger nbulger at integralgroup.com
Thu Feb 6 07:21:17 PST 2014


A very interesting device you are trying to model! I assume it looks
something like this:

In looking at the diagram and spec, I think their air cooled chiller acts
most like a non integrated waterside economizer. The free cooling either
does everything or it does nothing.

I would advise

   1.  setting up 1 CHW loop with an Air cooled chiller and the WSE chiller
   2. The WSE chiller should autosize to whatever the air cooled chiller
   is. For safety, I might just put in the size manually.
   3. Create a CW loop and tower to attach to the WSE chiller
   4. Set the tower to be a closed tower, so water does not evaporate and
   it acts just like the air cooled condenser coil of your product
   5. Manually size the cooling tower
   6. Set the CW loop to size based on the Secondary equipment. The loop
   defaults to the primary equipment, which in this case is our WSE chiller
   which might crash or not size. By selecting secondary, the loop will now
   look at the cooling tower and determine it's size
   7. Use the CHW plant manager and sequence the chillers so the WSE
   chiller always goes first. It may not be able to provide cooling if it is
   to hot outside but it will always try to and succeed when weather permits.

The other thing I would recommend is getting the chiller curves right. The
product I found says they have a buffer tank for refrigerant to help
balance out demand and smooth out compressor performance. I bet this is
doing a lot more for efficiency than the WSE is and should be included.



*Neil Bulger, PE* | Energy Modeling Team Manager

*Integral Group *| 427 13th Street | Oakland CA USA 94612
T 510.663.2070 x235
c 707.363.3954

integralgroup.com <http://www.integralgroup.com/> |
nbulger at integralgroup.com

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On Thu, Feb 6, 2014 at 7:10 AM, <bfountain at greensim.com> wrote:

> You cannot set that with range and approach. eQUEST calculates if the
> tower can carry the loop load for each timestep and if it can, the WSE is
> used. Otherwise the chiller is engaged.
> Brian Fountain
> bfountain at greensim.com
> -----Original Message-----
> From: Sebastian Carrizo <juan.carrizo at alumni.carleton.ca>
> Sender: equest-users-bounces at lists.onebuilding.org
> Date: Thu, 6 Feb 2014 09:59:58
> To: Neil Bulger<nbulger at integralgroup.com>
> Cc: equest-users at lists.onebuilding.org<equest-users at lists.onebuilding.org>
> Subject: Re: [Equest-users] Free cooling Chiller on eQuest
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