[Equest-users] How to set the COP of a chiller as constant in eQuest?

Esmireta e2fye2 at 163.com
Wed Apr 24 07:00:44 PDT 2013


Hi Wesley,
Thanks for your reply!
Actually, air-cooled chiller is required per ASHRAE90.1, thus, no energy consumption from cooling tower and cooling pumps will be included.
Thanks!
Esmi






At 2013-04-23 04:44:44,"Wesley S. Care" <wesley.care at esdaz.com> wrote:


Another point that might help some folks who are trying to model constant chiller COPs:

 

I needed to use the existing district plant method for a local utility rebate recently, and by inspecting the PS-H report for my “chiller,” which represented the plant, I found that I was not getting constant EIRs after creating my own curves, etc. It was also not a constant error, getting worse in the cooler months and closer to my expected value in the summer.

 

The fix was to remove any peripherals or vampire loads from the chiller power in the chiller properties dialog. I modeled the plant as a single, air-cooled chiller, set my calculated EIR, applied the flat curves (as noted by others below), allowed the “Min Ratio” to go down to 0.01, set “Elec to Condenser” to zero (assuming that is already calculated in my overall EIR), and set “Start-up Time” and “Standby Time” to zero, since in reality the water is available when the building needs it and we’re not firing up a chiller just for me.

 

Seemed obvious after the fact, but drove me crazy for a little while.

 

Thanks,

      Wesley

                 

Celebrating 25 Years

Mechanical Engineers + Electrical Engineers + Sustainable Design

 

Wesley Care, EIT | Mechanical Project Engineer|* wesley.care at esdaz.com|(480.481.4973|6480.481.4903

 

From: Nick Caton [mailto:ncaton at smithboucher.com]
Sent: Monday, April 22, 2013 9:41 AM
To: Joe Huang; Esmireta
Cc:equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] How to set the COP of a chiller as constant in eQuest?

 

This is something I haven’t ever fully resolved for myself actually… eQuest contains a set of DOE-2.2 manual volumes, found under the eQuest “Help” menu. 

 

I believe the first 4 volumes are the “core” DOE2.2 volumes, and the other volumes have been appended over time as eQuest/DOE2 have developed in more recent years.  I’m not clear on whether these in sum are any more or less “complete” than past or present manuals for the underlying DOE2 simulation engine itself.  I am pretty sure some parts of this are compiled by & for eQuest specifically (Volume 5: Compliance Analysis in particular jumps to mind).

 

More specifically to Esmireta’s follow up query, you can find the entry I cited on Chiller Energy Consumption, and explore the associated inputs further, in a few ways:

 

First, navigate to “DOE-2 Help” from the Help context menu.

From here, you can navigate to the previously appended chiller energy consumption entry.  Here’s a better citation for those who aren’t seeing images in my emails:  Volume 2 > HVAC Components > CHILLER > Chiller Energy Consumption.  You can also read up on all the associated BDL inputs by highlighting the branch elements following in the tree view:

 

Second, while working in eQuest and particularly after the wizards, you can also right-click most input fields to pull up a context-sensitive index of sorts to lead you to appropriate entries in the DOE2 manuals – this is the primary way I access & navigate the supporting documentation in practice:

 

Regards,

 

~Nick

 

 

 

NICK CATON, P.E.

SENIOR ENGINEER

 

Smith & Boucher Engineers

25501 west valley parkway, suite 200

olathe, ks 66061

direct 913.344.0036

fax 913.345.0617

www.smithboucher.com

 

From:equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Joe Huang
Sent: Monday, April 22, 2013 10:40 AM
To: Esmireta
Cc:equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] How to set the COP of a chiller as constant in eQuest?

 

I was referring to the DOE-2 Supplement, Version 2.1E, produced by LBNL in 1993 (LBL-34947).  I have not looked at the help function of eQUEST, so I can't tell how detailed is it.

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 108D
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
www.whiteboxtechnologies.com
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"


On 4/21/2013 9:49 PM, Esmireta wrote:

Hi Joe,

Thanks for your reply!

Is the DOE-2.2 manual the DOE help in the eQuest?

Esmi





At 2013-04-18 03:17:00,"Joe Huang" <yjhuang at whiteboxtechnologies.com> wrote:

Do you not have a copy of a DOE-2.2 or DOE-2.1E manual?  That would make it hard to understand how DOE-2 works.
DOE-2 has many performance curves, depending on the type of equipment. The EIR-FT curves are either bi-linear or bi-quadratic functions of the entering wetbulb and outdoor drybulb temperature.  The EIR-FPLR curves can be linear, quadratic, or cubic functions of the Part Load Ratio (PLR).

By the way,what I said yesterday was in reference to packaged SYSTEMS.  If your model contains a PLANT model with a Chiller, then
the keywords for the chiller performance curves change somewhat.

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 108D
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
www.whiteboxtechnologies.com
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"


On 4/16/2013 11:09 PM, Esmireta wrote:

Hi Joe,

In the simulation of a district cooling system, the guidance requires a virtual plant with a constant average efficiency.

In the DOE curves, how can I know the meaning of the equation and the coefficients in it? It seems there is no useful information in the DOE help.

Thanks!

Esmi





At 2013-04-17 10:35:35,"Joe Huang" <yjhuang at whiteboxtechnologies.com> wrote:

DOE-2 modifies the COOL-EIR using several curves COOL-EIR-FT as a function of outdoor conditions and COOL-EIR-FPLR as a function of the Part Load Ratio. I suppose you could set those to be constant. Another way would be to just take the Cooling Load from the SS-D report and divide that by your constant COP.  But my question would be, why do you want to do that ?

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 108D
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
www.whiteboxtechnologies.com
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"


On 4/16/2013 6:55 PM, Esmireta wrote:

Dear all,

I wonder how to set the COP of a chiller as constant? after I set the chiller type, the electric input ratio type is determined, which means the self-made constant curve cannot be input.

Thanks!

Esmi





 
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