Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
I am seeing very similar results in V9.3 (not yet released) so this is an issue in EnergyPlus. I would agree that COP should be constant with these inputs (unless I'm missing something). I will post an issue on GitHub. I also see the VRF HP PLR and RTF are not equal using the unity Cooling/Heating Part-Load Fraction Correlation Curves, this also seems wrong.
| | 2 | No.2 Revision |
I am seeing very similar results in V9.3 (not yet released) so this is an issue in EnergyPlus. I would agree that COP should be constant with these inputs (unless I'm missing something). I will post an issue on GitHub. I also see the VRF HP PLR and RTF are not equal using the unity Cooling/Heating Part-Load Fraction Correlation Curves, this also seems wrong.
Update 1/21/20:
The Cooling/Heating Energy Input Ratio Modifier Function of Low/High Part-Load Ratio Curve cannot be 1. It must be proportional to PLR. When I made those changes in 4 places I get this. I'm still not sure of the changing cooling COP but I am getting closer to what you expect.
| | 3 | No.3 Revision |
I am seeing very similar results in V9.3 (not yet released) so this is an issue in EnergyPlus. I would agree that COP should be constant with these inputs (unless I'm missing something). I will post an issue on GitHub. I also see the VRF HP PLR and RTF are not equal using the unity Cooling/Heating Part-Load Fraction Correlation Curves, this also seems wrong.
Update 1/21/20:
The Cooling/Heating Energy Input Ratio Modifier Function of Low/High Part-Load Ratio Curve cannot be 1. It must be proportional to PLR. When I made those changes in 4 places I get this. I'm still not sure of the changing cooling COP but I am getting closer to what you expect.
Further Update 1/21/20:
The changing cooling COP was due to the Cooling/Heating Part-Load Fraction Correlation Curve not being 1.
| | 4 | No.4 Revision |
I am seeing very similar results in V9.3 (not yet released) so this is an issue in EnergyPlus. I would agree that COP should be constant with these inputs (unless I'm missing something). I will post an issue on GitHub. I also see the VRF HP PLR and RTF are not equal using the unity Cooling/Heating Part-Load Fraction Correlation Curves, this also seems wrong.
Update 1/21/20:
The Cooling/Heating Energy Input Ratio Modifier Function of Low/High Part-Load Ratio Curve cannot be 1. It must be proportional to PLR. When I made those changes in 4 places I get this. I'm still not sure of the changing cooling COP but I am getting closer to what you expect.
Further Update 1/21/20:
The changing cooling COP was due to the Cooling/Heating Part-Load Fraction Correlation Curve not being 1.
Update 1/22/20:
These curves cannot be 1 and must be proportional to PLR (i.e., second term = 1, not the first). Actually, I think the High EIRfPLR curves can remain 1 since when the high PLR curve is used when the PLR >= 1.
CoolingEIRLowPLR, !- Cooling Energy Input Ratio Modifier Function of Low Part-Load Ratio Curve Name
CoolingEIRHiPLR, !- Cooling Energy Input Ratio Modifier Function of High Part-Load Ratio Curve Name
HeatingEIRLowPLR, !- Heating Energy Input Ratio Modifier Function of Low Part-Load Ratio Curve Name
HeatingEIRHiPLR, !- Heating Energy Input Ratio Modifier Function of High Part-Load Ratio Curve Name
And these curves must be 1 so no cycling losses are modeled.
VRFCPLFFPLR, !- Cooling Part-Load Fraction Correlation Curve Name
VRFCPLFFPLR, !- Heating Part-Load Fraction Correlation Curve Name
