# Re: [EnergyPlus_Support] Re: EIR Chiller Performance Curve Fitting

```Hi Charlie,

As you know 1) the PRL is equal to the rated cooling load divided by the available cooling load. e.g. from the manufacture, tha standard rating for the specific leaving chilled water temperature (6.7oC) and the entering air temperature (35oC).
2) the value ChillerEIRFPLR (Y) is EIRavailable / (EIRdesign x PRL).  You can refer to the EngineeringDoc P.338.

SAMLEE

applezealot <applezealot@xxxxxxxxxxxx> 說：
Dear sam

I check your excel file. I have some question about your
calculation:
1. You used (Qr/Qa) as PLR and (Pa/Pr) as EIR output ratio for the
third.I get confused about these settings. Could you please tell me
why you choose these parameters? P.S. Pa,Pr,Qa,Qr are power
available, power rated, capacity available and capacity rated.
2. And I look into the curve fitting results in sheet1 of your
file. Is it related to our discussion?  I can not understand the
purpose of this sheet. Please explain it for me.

Thank you in advance
charlie

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, wing sun lee
<samwslee@y...> wrote:
> Hi,
>
> Please go here
http://groups.yahoo.com/group/EnergyPlus_Support/Files/Problem_Submit
tals/Input Problem/Fit curve biquadratic d.xls
>
> It seems to be corrected and solved
>
> SAMLEE
>
>
> donbshireyiii <shirey@f...> 撰寫:
> Charlie and SAMLEE,
>
> In the spreadsheet you are using, it looks like EIR as a function
> of PLR is not being properly calculated.
>
> The spreadsheet seems to be using available capacity at the current
> operating conditions divided by the design (rated) capacity of the
> chiller.  This is not correct.... is should be just as the
> input/output reference says... PLR = (cooling load) divided by
> (available capacity at the current operating conditions).
>
> Don
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, wing sun lee
> <samwslee@y...> wrote:
> > Hi Charlie,
> >
> > I just use your advice that the PRL shoudl equal to the ratio of
> cooling load to the available capacity.
> > Please see my attached file at
> http://groups.yahoo.com/group/EnergyPlus_Support/F
> iles/Problem_Submittals/Input
> Problem/Fit curve biquadratic b.xls
> >
> > SAMLEE
> >
> > energypluser <energypluser@y...> 撰寫:
> > Dear Mike,
> >
> >      I wanna simulate a electric chiller with the EIR module.
And I
> > found that you give a EXCEL example for the curve fitting. But I
> think
> > the third curve in your example file may not be correct.
> >      According to the input/output reference, the third curve is
> the
> > EIR output ratio in function of Part Load Ratio. The PLR
> calculation in
> > your file is the ratio of the available capacity to the nominal
> > capacity.  In my opinion, PLR should equal to the ratio of the
> cooling
> > load to the available capacity. Am I right?
> >       If I am right, could you please tell me how to obtain the
> third
> > curve for my simulation based on the manufacturer catalog.
> >       Thank you in adavance
> >
> >
charlie
>
>
>
>
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