[Equest-users] Centrifugal Chiller Curves

Wed Apr 8 19:21:48 PDT 2015

David/Nick,

The virtual chiller idea makes a lot of sense. I will play around with it tomorrow. I remember reading the post that you attached after re-reading. Too bad my sleep deprived brain couldn't get there first. 

Thanks,

-Jordan.

Sent from my iPhone

> On Apr 8, 2015, at 6:55 PM, Nicholas Caton <ncaton at catonenergy.com> wrote:
> 
> Jordan:
>  
> With respect to WSE, my practice to handle simultaneous chiller/WSE operations is to “roll my own” waterside economizer “chiller/heat-exchanger” leveraging load management inputs.  I’ve attached a discussion wherein I provided an outline for a starting point, and have also copied that text below this response since my attachments haven’t been working of late.
>  
> In short, you should be able to have your WSE operation function independently of the other chillers on the same loop.  It will be up to you to build on this framework to be sure to account for the pumping/fan energies/additional head associated with that “free cooling” operation (as applicable).
>  
> ~Nick
>  
> NICK CATON, P.E.
> Owner
>  
> Caton Energy Consulting
>   1150 N. 192nd St., #4-202
>   Shoreline, WA 98133
>   office:  785.410.3317
> www.catonenergy.com
>  
> Hi Nikola, good to hear from you!
>  
> An approach I like to start with (sometimes this is a rough approximation, other times it is very accurate & appropriate), is:
> 1.       Establish an outside temperature at and below which the waterside economizer is designed to handle the building’s cooling loads (or largely so)
> 2.       Create a “free cooling” chiller with an EIR a hair above zero (something like 0.0000001), attach it to the CHW loop(s) servicing your coils, alongside the regular chiller(s)
> 3.       Create a pair of equipment control sequences:  “Free” and “Normal”
> a.       For the “Free” control sequence, assign the “free cooling chiller” in the first row to handle loads first. You may optionally also assign the actual chillers and associated capacity ranges for each.
> b.      For the “Normal” control sequence, specify your normal chiller sequence of operations
> 4.       Then create a Load Management of type OA-TEMP. 
> a.       Set the outside air temperature below which free cooling is active under management sequence 1, and assign the free cooling control sequence defined in the previous step.
> b.      Set management sequence 2 to a maximum OSA temp of 999, and assign the normal control sequence from the previous step
>  
> Integrating WSE into eQuest is one of those things I always plan on spending extra time on – the devil is in the details!  I don’t believe waterside economizer systems are something you can make a simple rote procedure around, as actual waterside economizer system operations/limitations are varied and nuanced.  Consider this a simple outline to convey the approach concept & get you started.  I would particularly advise paying close attention to your pumping and heat rejection energies from this point forward.
>  
> Hope that helps get you started - Happy new year!
>  
> ~Nick
>  
> NICK CATON, P.E.
> Owner
>  
> Caton Energy Consulting
>   1150 N. 192nd St., #4-202
>   Shoreline, WA 98133
>   office:  785.410.3317
> www.catonenergy.com
>  
> From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nikola Kravik
> Sent: Tuesday, December 30, 2014 8:45 AM
> To: equest-users at lists.onebuilding.org
> Subject: [Equest-users] Water side economizer
>  
> Hi eQuest users,
>  
> Can you please share your experiences with implementing WSE successfully and workarounds in v3.65?
>  
> Thank you,
> Nikola   
>  
> Nikola Kravik, BEMP, LEED AP
> Energy Engineer
> ASHRAE Golden Gate BOG
> IBPSA USA San Francisco Committee
>  
> Willdan Energy Solutions
> Celebrating 50 years of service
>  
> 6120 Stoneridge Mall Road, Suite 250
> Pleasanton, CA 94588
> T. 925.416.4200 ext. 1228
> D. 925.416.4228
> C. 925.719.5883
> F. 925.737.0174
> Email: nkravik at willdan.com
> www.willdan.com
>  
>  
> From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Brian Fountain
> Sent: Wednesday, April 08, 2015 4:12 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
> Subject: Re: [Equest-users] Centrifugal Chiller Curves
>  
> Michael,
>  
> Thanks for the spreadsheet. That is definitely more elaborate than the one I put together.
>  
> I was able to successfully model air-cooled screws using the spreadsheet I attached, but the issue I'm running into with the water-cooled centrifugals is that the capacity provided by the rep does not change as a result of entering condenser water temperature. KW changes, but tonnage does not. This creates an unrealistic curve for CAPFT and EIRFT.
>  
> I'm at the mercy of the reps to provide this data and so far I have struck out. I was just curious if there was something I'm missing. Does something need to be held constant that will allow the capacity to change based on entering condenser water temperature and leaving chilled water temperature?
>  
> 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> 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
> M. 310.387.2083
> mbusman at opterraenergy.com
>  
> 
>  
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>  
>  
>  
>  
> From: Equest-users [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
> 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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