[Equest-users] using IPLV in eQuest

R B slv3sat at gmail.com
Fri Feb 25 10:32:04 PST 2011


Thanks all. As I thought all along, seems like there is no easy way out.
Any ideas on how HAP/TRACE treat chiller simulation? Do they use IPLV's or
do they have many more options for performance curves or is it same as
eQuest?

On Fri, Feb 25, 2011 at 12:21 PM, Nick Caton <ncaton at smithboucher.com>wrote:

>  James et al,
>
>
>
> Rohini will need to create performance curves to make this particular
> comparison.  Otherwise using the default curves will result in identical
> part load performances.
>
>
>
> The following is excerpted from the following (short) recommended reading
> concerning what IPLV means:
> http://ashrae-cfl.org/2010/03/understanding-iplvnplv/
>
> IPLV (or NPLV) = 0.01A+0.42B+0.45C+0.12D
>
> Where:
>
> A = COP or EER @ 100% Load
>
> B = COP or EER @ 75% Load
>
> C = COP or EER @ 50% Load
>
> D = COP or EER @ 25% Load
>
> John is saying knowing only the IPLV and the 100% load condition efficiency
> (variable ‘A,’ above) is not enough information to extrapolate the IPLV
> curves to compare the two chillers.
>
>
>
> For the exercise of comparing the two non-centrifugal chillers of the same
> technology/type, I would just focus on making a custom EIR-FPLR (not
> EIR-fPLR&dT) for each chiller, and use the library CAP-FT AND EIR-FT curves.
>  My understanding is the effects of temperature on capacity and EIR outside
> of centrifugal VSD chillers is negligible.  NOTE:  Whenever using any of the
> default library chiller performance curves, that means you MUST normalize to
> and specify the chiller at ARI conditions – those curves aren’t normalized
> to anything else.
>
>
>
> So!  If you can find the IPLV A, B, C and D values for both chillers’
> curves, you could come up with your EIR-FPLR curve coefficients (*curve
> type = quadratic or cubic*) using a curve-fit in excel… or alternatively
> make eQuest figure the coefficients by entering those points as raw data.
>
>
>
> You may more easily just make your own curves, following John’s advice and
> getting part load unloading curves (100%, 90%, 80%... etc) held at a
> constant chilled & condenser temperature to match the ARI* conditions (85CWT
> if this is water cooled) at which you’re specifying the chiller
> capacity/EIR.  Again, you could either go into excel, normalize the data
> (review DOE2 help entry for EIR-FPLR), make a scatter chart, and get the
> coefficients using a curve fit… or enter the data as raw points into eQuest
> and the coefficients will be figured by eQuest… whatever makes more sense to
> you.
>
>
>
> For others and personal future reference…. If you are looking to make an *
> EIR-fPLR&dT* curve (for centrifugal chillers or otherwise):  Ask your rep
> instead for multiple (minimum 3) part load unloading runs, holding the
> delivered chilled water temp constant, and vary the condenser water
> temperature incrementally for each run (i.e. 85, 75, 65).  Choose a range of
> CWT’s that cover the anticipated range to be encountered in the actual
> design. This will get you enough data to have the minimum 3 delta-T’s
> represented in your part load data points to build this curve correctly.
> You’ll be using eQuest “raw-data” entry method to make it generate the
> coefficients.
>
>
>
> ~Nick
>
>
>
> * Rather than ARI conditions (85F CWT), you could be normalizing to Design
> condition EIR/CAP, provided you’re making a full set of custom curves in the
> same fashion.
>
>
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *NICK CATON, E.I.T.***
>
> PROJECT ENGINEER
>
> Smith & Boucher Engineers
>
> 25501 west valley parkway
>
> 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 *James Waechter
> *Sent:* Friday, February 25, 2011 10:55 AM
> *To:* equest-users at lists.onebuilding.org
>
> *Subject:* Re: [Equest-users] using IPLV in eQuest
>
>
>
> John,
>
>
>
> If the only parameter Rohini enters into the program is the full-load EIR –
> which he said is the same for both chillers – how will eQuest know to bend
> the curves differently for the two chiller options.  It is my understanding
> that program would use the same chiller efficiency curves for both machines
> even though their IPLVs are different.
>
>
>
> In order to overcome this issue, are you saying Rohini should get chiller
> performance data from each of the manufacturers and enter his own custom
> curves?  I recall there was a discussion on that topic a few months back.
>
>
>
> Regards,
>
> James Waechter Jr., P.E., CEM, LEED A.P.
> Energy Engineer – Rocky Mountain Region
> p 303 215 4062 | m 727 686 3248
>
> *McKinstry*
> Consulting | Construction | Energy | Facility Services
>
> www.mckinstry.com
>
>
>
>
>
>
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *John Aulbach
> *Sent:* Friday, February 25, 2011 9:41 AM
> *To:* R B; eQUEST Users List
> *Subject:* Re: [Equest-users] using IPLV in eQuest
>
>
>
> Rohini:
>
>
>
> Won't happen. IPLV is a number which has one equation and 4 unknowns.
> Actually, three unknowns as you know the 100% point. You need a
> manufacturer's curve run at 85F constant condenser water temperature. Let
> eQuest do the curve bending after that. ARI curve won't work right.
>
>
>
>
>
> John R. Aulbach, PE, CEM
>
> Senior Energy Engineer
>   ------------------------------
>
> *Partner** **Energy***
>
> 1990 E. Grand Avenue, El Segundo, CA 90245
> W: 888-826-1216, X254| D: 310-765-7295 | F: 310-817-2745
>
> www.ptrenergy.com | jaulbach at ptrenergy.com
>
>
>  ------------------------------
>
> *From:* R B <slv3sat at gmail.com>
> *To:* eQUEST Users List <equest-users at lists.onebuilding.org>
> *Sent:* Fri, February 25, 2011 7:25:18 AM
> *Subject:* [Equest-users] using IPLV in eQuest
>
> Hi All,
>
> I would like to compare two screw chillers with same full load kW/ton and
> different IPLV kW/ton. I am using the full load number for the EIR. Where
> can the IPLV number be used? Is there some way to scale the performance
> curves to reflect different IPLV's?
>
> -Rohini
>
>
>
>
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