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[EnergyPlus_Support] Re: Unrealistic ChillerEIRFPLR curves for data in the file: Chillers.idf?

Dear Damian,

2-4 times the peak capacity COP sounds like a stretch for believability.
On the other hand, improved part load COP is exactly the goal to be
striven for, since the vast majority of operation hours are at part
load.  I suspect that the "typical" COP vs PLR values in the example
file do not represent a specific chiller and may not represent most
chillers.  It's a good place to start, but if you can derive a curve for
the actual chiller, that is preferred!

I have not developed part load curves often enough to pretend that I am
an expert, but most chiller manufacturers publish performance with
varying entering water temps, delta T and condenser water temp / delta
T.  In theory, that allows you to create a performance curve which
incorporates those variables, although it sounds challenging.  I have
not needed to do so yet, so I've put off the task.  As I recall, the
information set varies quite a bit among the major manufacturers, so
standardization might be difficult.

This, it seems, is an opportunity for the modeling community.  I started
the process a while back by setting up a standard representation of
performance with those variables, but haven't figured out how to do the
curve-fit for multiple variables.  If you figure it out or someone else
has already figured it out, please share the information!

Actually, it would be VERY nice if the manufacturers would publish these
curves...


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "d_h51@..." <d_h51@...>
wrote:
>
> Hi all,
>
> When I plot the COP vs PLR dependence taken from the file
'Chillers.idf'
> for specific chillers (please see the file COP vs PLR
> (EnergyPlus).jpg
>
<http://f1.grp.yahoofs.com/v1/cA3eSXpIH0plWrUAXrH171qOeNo_sglXxA6WFL-5A1\
\
>
c9cj_Ewy5DotS8QUGcGAVrG8-yS_ZOkZM7K4eZBiXgSaqQ_1FPQsMlalsOvFE/_Problem_S\
\
> ubmittals/COP%20vs%20PLR%20%28EnergyPlus%29.jpg> ) it shows that for
> some chillers at e.g. PLR=0.4 the COP is 4times higher than for PLR=1,
> and for PLR =0.5 most of the chillers have 2times higher COP than at
> PLR=1.
>
> For me it's unrealistic, especially when i compare these results to
the
> catalogue data given from the producers (where the COP/COP_ref value
> reaches its maximum usually for PLR=0.5 and is about 1.6)
>
> Do I do a mistake somewhere? COP/COP_ref = 1/ChillerEIRFPLR, right?
>
> Or maybe this problem is related to my next question:
> COP vs PLR performance in catalogue data is mostly rated under ARI
> conditions, for instance for water2water chillers and PLR=1 ECWT=29.4C
> and for PLR=0.5 ECWT=18.3C. Do the ChillerEIRPLR curves are rated for
> constant ECWT? If yes how can I modify PLR curves rated according to
ARI
> standard into curves for constant ECWT?
>
> Thanks for any help in advance,
> Damian
>





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