[Equest-users] Centrifugal Chiller Curves

Wed Apr 8 16:46:48 PDT 2015

Jordan:

You can use the equipment management to allow one virtual chiller that is the WSE to run up to a certain capacity, then stage on a single chiller, and then a virtual chiller that is equivalent to the performance of the two SCF chillers as a unit.

The chiller vendor most likely will need to provide the performance data of the two SCF chillers working together as a unit. I’m not sure you have the data necessary to construct that performance curve yourself from the standard submittals.

So to be clear, you’ll have three chillers in your model:

1.       Equivalent WSE chiller

2.       A single chiller, as designed

3.       A virtual chiller for both machines operating in series counterflow

You won’t have two single chillers as designed, eQUEST would operate these in parallel instead of in series.

David

David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
Grumman/Butkus Associates

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Brian Fountain
Sent: Wednesday, April 08, 2015 6:12 PM
To: jordan jackson; Michael Busman; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Centrifugal Chiller Curves

DOE-2.3 (eQUEST 3.70) does serial chillers. DOE-2.2 does not and as you observed the WSE will only work when it can take all the load. Have not tried. The DOE-2.3 WSE in series.

From: jordan jackson
Sent: Wednesday, April 8, 2015 6:31 PM
To: Michael Busman; equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: Re: [Equest-users] Centrifugal Chiller Curves

Michael,

…deleted…

On a similarly frustrating note... I'm trying to come up with a workaround to model series chillers in eQuest with free cooling on the upstream chiller. From reading the DOE manual it seems waterside economizer won't do what I need it to since I can't be in WSE and supplementing with the downstream chiller. I considered combining performance of the two chillers into one machine, but I haven't totally figured out how that will work.

Any ideas are welcome.

Thanks,

Jordan Jackson.

On Tue, Apr 7, 2015 at 8:44 AM, Michael Busman <mbusman at opterraenergy.com<mailto:mbusman at opterraenergy.com>> wrote:
Jordan,

Many, many years ago I used to do a lot of modeling in VisualDOE.  I don’t do much in eQUEST or other simulation program anymore.

Anyway, I’ve attached a spreadsheet I put together way back when that is based on calculation methodology that was published by Pacific Gas & Electric.  If you look through the tabs you’ll see that I have some sample data that is used to calculate the curve coefficients.  Originally it was based on a constant speed chiller, however, a few years ago I added a tab for a variable speed chiller.

Don’t expect the manufacturers’ reps to produce the curves for you but they should be able to generate the data you need.  Key to this for reasons I don’t recall is that the reps need to generate at least 10 data points of full load data at different chilled and condenser water temperatures in order to map the chiller.  You will also need several part load data points at different water temps also.  If you give the reps the blank data sheet they should be able to run their software to generate the data you need.

Browse through the spreadsheet tabs and hopefully it will make sense to you.  Any questions, I’ll do my best to answer you, however, please remember that it’s been a long time since I’ve developed custom curves.

My best,

Mike

Mike Busman, C.E.M.
Lead Project Engineer

765 The City Dr South Suite 475
Orange, CA 92868
T.   657-216-3261<tel:657-216-3261>
M. 310.387.2083<tel:310.387.2083>
mbusman at opterraenergy.com<mailto:mbusman at opterraenergy.com>

[OpTerra]<http://opterraenergy.com/>

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From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org>] On Behalf Of jordan jackson
Sent: Monday, April 06, 2015 3:55 PM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: [Equest-users] Centrifugal Chiller Curves

I have been using eQuest to evaluate chiller performance for retrofit projects. I have not had a problem modeling air-cooled, but I can't seem to get the data from the reps that I would like for water-cooled centrifugal projects. I have settled on using standard curves for CAPFT and EIRFT and using a cubic curve with coefficients created through a curve fit in excel for EIRFPLR.

The manufacturers reps aren't able to produce a capacity or EIR curve as a function of temperature (entering condenser water temp). Has this been everyone's experience with this.

I'm attaching the excel file I created to calculate all of this.

Any feedback is appreciated. I'm just concerned about the data I'm reporting to the client without touching those curves.

Thanks,

Jordan Jackson.

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