# Description of Chiller EIRFPLR in I/O Reference

I customised chiller performance curves of Chiller:Electric:EIR based on manufacturer's technical data.

I think the description of Electric Input to Cooling Output Ratio Function of Part Load Ratio Curve Name in I/O Reference is incorrect. I/O Reference says that "This curve is generated by dividing the operating electric input power by the available full-load capacity (do not divide by load) at the specific operating temperatures.", but I think the curve should be generated by dividing the operating electric input power by the rated electric input power.

I think the description in Engineering Reference is correct.

Pleaese correct me if I'm wrong.

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The nature of EIR is power (W) / cooling capacity (W), so I'm confident that the I/O Reference is correct. You might check the definition of EIR to gain confidence about this.

( 2023-01-23 04:52:00 -0500 )edit
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I know the definition of EIR. The problem is that this curve does not represent EIR. I think the curve name should be changed to avoid confusion. In this paper, @rraustad explains Cooling Energy Input Ratio Modifier Function of Part-Load Ratio Curve. He says that "The name of this curve is somewhat misleading in that this curve is a ratio of operating power to rated power". Although this paper is for VRF performance curves, I think the same is true of the chiller performance curve.

( 2023-01-30 22:27:54 -0500 )edit
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The curve in question:

this->ChillerEIRFPLR = Curve::CurveValue(state, this->ChillerEIRFPLRIndex, PartLoadRat);


with

this->Power = (AvailChillerCap / ReferenceCOP) * this->ChillerEIRFPLR * this->ChillerEIRFT * FRAC;


So EIRFPLR needs to provide the fraction of full load power at operating PLR.

Note that FRAC represents the chiller cycling on and off, not the fraction of full load power.

( 2023-02-02 10:54:13 -0500 )edit