Description of Chiller EIRFPLR in I/O Reference

asked 2023-01-22 10:37:28 -0500

Keigo's avatar

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.

image description

I think the description in Engineering Reference is correct. image description

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.

Jim Dirkes's avatar Jim Dirkes  ( 2023-01-23 04:52:00 -0500 )edit

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.

Keigo's avatar Keigo  ( 2023-01-30 22:27:54 -0500 )edit

The curve in question:

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


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.

rraustad's avatar rraustad  ( 2023-02-02 10:54:13 -0500 )edit