[Equest-users] IPLV Curve Fit

[Lyle Keck]

All,

I am trying to create a part load curve for an air-cooled screw chiller.  I have the EER & COP data for 100%, 75%, 50%, and 25% loading.

I have read through the various posts in the archives and I am still unsure if I should input this data as 'raw data' or 'coefficients'

>From previous posts:

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

It is my understanding that EIR-PLR curves give the EIR as a function of part load ratio.

SO, if I create a 'cubic' curve with input type 'curve coefficients', and input a=(1/COP-100%), b=(1/COP-75%), c=(1/COP-50%), and d=(1/COP-25%) and specify this curve as the EIR - f(part load ratio) curve, would that be accurate?

Additionally, this chiller has a condenser water temp of 95 degF and design conditions that differ from AHRI conditions (design EWT=58 degF and LWT=44 degF)
Do these values have direct correlation to the curve creation ? Or can the condenser and CHW temp simply be defined in the 'basic specifications' tab for the chiller, and the EWT defined via the CHW loop deltaT?

I know this topic has been widely discussed, but I am still uneasy about the actual inputs for the creation of the part load performance curve.

Any input, or reference to a previous post would be appreciated.

Thanks in advance,

Lyle Keck
SustainablE Systems Analyst



AEI | AFFILIATED ENGINEERS, INC.
Westlake Center Office Tower, 1601 Fifth Avenue, Suite 1400 | Seattle, WA  98101

P: 206.256.0800 | F: 206.256.0423
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