[Equest-users] Waterside Economizer

[Demba Ndiaye]

There are two loops as you know: the condenser water (CW) and the chilled water (CHW) loops. The economizer acts on the CHW side, and the cooling towers, on the CW sides. Basically, the water-side economizer may be seen as a chiller with no compressor.

In some cases, economizers are used to pre-cool the return chilled water (CHW loop) before it gets back to the chillers: that is what the rule 1 below precludes.

________________
Demba NDIAYE

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Sami, Vikram
Sent: Monday, June 28, 2010 2:58 PM
To: Howe, Timothy; Varkie C Thomas
Cc: Sethi, Amarpreet; equest-users at lists.onebuilding.org; Jonathan Smith
Subject: Re: [Equest-users] Waterside Economizer

I do have a question about that - point # 1  - A water-side economizer cannot precool the return flow prior to entering the chillers.

I might be showing my ignorance here, but - isn't that what the cooling tower does? So if you have a CHW loop with two chillers attached - a normal (lets say centrifugal) chiller and a water side economizer. When the water side economizer cannot satisfy all the load, it would switch completely to the centrifugal. However - wouldn't the cooling tower still be used as a heat rejection to " precool the return flow prior to entering the chillers"? In which case is point 1 not really a shortcoming?

Vikram Sami, LEED AP
Sustainable Design Analyst
1382 Peachtree St. NE, Atlanta, GA 30309
t: 404-443-7462    f: 404.892.5823       e: vikram.sami at perkinswill.com   www.perkinswill.com<http://www.perkinswill.com/>
Perkins+Will.  Ideas + buildings that honor the broader goals of society


From: Howe, Timothy [mailto:Timothy.Howe at stantec.com]
Sent: Monday, June 28, 2010 2:49 PM
To: Sami, Vikram; Varkie C Thomas
Cc: Sethi, Amarpreet; equest-users at lists.onebuilding.org; Jonathan Smith
Subject: RE: [Equest-users] Waterside Economizer

The only problem is this:

[cid:image001.png at 01CB16DF.5BF545B0]


Timothy Howe, MS, LEED® AP
Mechanical Engineer
Stantec
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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Sami, Vikram
Sent: Monday, June 28, 2010 2:44 PM
To: Varkie C Thomas
Cc: Sethi, Amarpreet; equest-users at lists.onebuilding.org; Jonathan Smith
Subject: Re: [Equest-users] Waterside Economizer

Varkie,
Which version of eQUEST are you using? If it's a new version then you should be able to model it as a chiller. See attached documentation - pg 68 (73 of the PDF)

Vikram Sami, LEED AP
Sustainable Design Analyst
1382 Peachtree St. NE, Atlanta, GA 30309
t: 404-443-7462    f: 404.892.5823       e: vikram.sami at perkinswill.com   www.perkinswill.com<http://www.perkinswill.com/>
Perkins+Will.  Ideas + buildings that honor the broader goals of society


From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Varkie C Thomas
Sent: Monday, June 28, 2010 1:08 PM
To: Varkie C Thomas
Cc: Sethi, Amarpreet; equest-users at lists.onebuilding.org; Jonathan Smith
Subject: Re: [Equest-users] Waterside Economizer

I am having a hard time getting �Chiller Type = Waterside Economizer� to work in eQ.  I received 2 messages recommending this as the solution.  I have 2 more saying that they have not been able to model WSE in eQ.  Please let me know if it is not supposed to work.

Unlike DOE2.1E this is the only minimum input required in eQ.  In this project during WSE operation we require a Clg-Twr leaving temp (Plate & Frame HX entering temp) of 42F so that the CHW temp leaving the HX is 44F or 46F.  The eQ default is 85F.  Even with this default and �Chiller Type = Waterside Economizer� I get the error message �Condenser Water Loop has Zero Design Flow�.

Unlike DOE2.1E there is no way of attaching a schedule for WSE operation.  I have attached eQ input-output �Without-WSE-1� and �With-WSE-2�; DOE2.1E definitions of WSE commands and keywords;  a sample DOE2.1E plant section input showing WSE; a schematic of Plate & Frame HX; and my eQ input for WSE and the resulting error message.  The attached project is dummy to test eQ for WSE.

Has anyone modeled WSE with eQ?  WSE works with DOE2.1E commands and keywords.  Does Waterside Economizer work with EnergyPlus (this project is also going to be modeled with E+ using Design-Builder interface for building and systems), TRACE or HAP

Varkie



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