[Equest-users] Free cooling Chiller on eQuest

Neil Bulger nbulger at integralgroup.com
Wed Feb 5 22:07:28 PST 2014


The water side economizer chiller should be thought of as a
secondary-cooling device on a CHW loop and will cause many head aches if
used by itself without any actual chiller object.  On a CHW loop, actual
chillers are the only elements that can be used to autosize a CHW loop and
any attached CW loop. Without one, loops will not size and the model will
crash.

The error you posted is only a partial story so it is hard to know the full
problem. My guess is you have the WSE chiller on a dedicated cooling tower
loop, possibly called DEFAULT-CW, and there is no other chiller attached to
this CW loop. In this case, the CW loop will not size itself upon
simulation because eQuest does not see the WSE as a primary source of
cooling. *You can manually size the loop, any pump, and the cooling tower
and the model should run.*

In a larger picture of accounting for WSE, eQuest can only really capture a
non-integrated water side economizing (WSE). This setup and control scheme
means that the WSE heat exchanger will only operate if the cooling tower
and HX are able to handle the full cooling load. In several scenarios, this
is a very rare occurrence given standard CHW supply temperatures and the
low wetbulb temperature required to make this for free.

It is possible to design a system where a WSE heat exchanger only handles
part of the load and pre-cools the return water before it goes to the
chillers which handles the remainder. However, it is impossible to model
such a system in eQuest. EnergyPlus and IES are the best bet for something
like this and even then, it can be tricky to capture the full benefit. It
would likely be easiest to post process the eQuest hourly outputs of the
cooling load if you have a true fully integrated WSE.

Happy eQuesting!

*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

 *Trust* | *Nurture* | *Inspire*

Please consider the environment before printing this email.



On Wed, Feb 5, 2014 at 1:34 PM, Sebastian Carrizo <
juan.carrizo at alumni.carleton.ca> wrote:

> Thanks for the quick responses. After setting the parameters to match my
> design conditions I keep getting the error
>
> *Tower: Dummy CT on loop DEFAULT-CW is not needed.  No simulation will be
> performed.   *
>
> Any thoughts?
>
>
> On Wed, Feb 5, 2014 at 3:52 PM, Paul Riemer <Paul.Riemer at dunhameng.com>wrote:
>
>> Some of these have an economizer functionality that can operate instead
>> of or in series with the compressors.  I was excited about this once but
>> the first pass showed it wouldn't payoff for my project.  If your situation
>> shows promise, you need a detailed model, and if an eQUEST waterside
>> economizer will not give you the series functionality, then I wonder if you
>> could model the modes as separate air cooled chillers in eQUEST with custom
>> curves for each and staging based on outdoor air or seasonal dates.  Good
>> luck.
>>
>> *Paul Riemer, PE, LEED AP BD+C*
>>
>> *DUNHAM*
>>
>>
>>
>> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
>> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Bishop, Bill
>> *Sent:* Wednesday, February 05, 2014 2:33 PM
>> *To:* Sebastian Carrizo; equest-users at lists.onebuilding.org
>> *Subject:* Re: [Equest-users] Free cooling Chiller on eQuest
>>
>>
>>
>> Sebastian,
>>
>> It sounds like you're talking about a water-side economizer, which can be
>> modeled as a WATER-ECONOMIZER, one of the chiller types in eQUEST.
>>
>> Regards,
>>
>> Bill
>>
>>
>>
>> *William Bishop, PE, BEMP, BEAP, LEED AP | Pathfinder Engineers &
>> Architects LLP*
>>
>> *Senior Energy Engineer*
>>
>> [image: webCertified_logo_colorRGB72DPI.jpg]
>>
>>
>>
>> 134 South Fitzhugh Street                 Rochester, NY 14608
>>
>> *T: (585) 698-1956 <%28585%29%20698-1956>              *          F: (585)
>> 325-6005
>>
>> bbishop at pathfinder-ea.com <wbishop at pathfinder-ea.com>
>> www.pathfinder-ea.com
>>
>> [image: earth for signature]Sustainability - the forest AND the trees.
>>
>>
>>
>>
>>
>> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
>> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Sebastian
>> Carrizo
>> *Sent:* Wednesday, February 05, 2014 3:15 PM
>> *To:* equest-users at lists.onebuilding.org
>> *Subject:* [Equest-users] Free cooling Chiller on eQuest
>>
>>
>>
>> Hi all,
>>
>>
>>
>> I'm trying to model a packaged air cooled/free cooling chiller in eQuest.
>> I was hoping someone could shed some light as to how one would go about
>> doing this.
>>
>>
>>
>> Regards,
>>
>> Sebastian
>>
>>
>>
>> --
>>
>> *Juan Sebastian Carrizo*
>>
>> M.Eng Sustainable Energy | B.Eng Industrial Engineering
>>
>> (c) 647-225-2243 | juan.carrizo at alumni.carleton.ca
>>
>>
>>
>>
>>
>
>
>
> --
>
> *Juan Sebastian Carrizo*
> M.Eng Sustainable Energy | B.Eng Industrial Engineering
>
> (c) 647-225-2243 | juan.carrizo at alumni.carleton.ca
>
>
>
>
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