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# Pumps in EnergyPlus Hi,

In the pumps section of EnergyPlus, it asks for 4 coefficients which in order to have them I need to use pump curves for the following equation:

FractionFullLoadPower = C1 + C2PLR + C3(PLR^2) + C4*(PLR^3) which I am using from the EngineeringReference of EnergyPlus. I would appreciate it if someone can help me figure out what is the meaning of "FractionFullLoadPower" and "PLR" for a pump? I have the performance curve of my pumps.

Thanks,

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I think you may have just read the Input/Output Reference guide for Pump:VariableSpeed, because the Engineering reference for Variable Speed Pumps seems pretty clear in terms of explaining what these are. I'll take the key information out and format it here for convenience.

PLR is the current requested volume flow rate divided by the nominal volume flow rate:

$$PartLoadRatio = VolFlowRate / NomVolFlowRate$$

FracFullLoadPower is calculated from the equation you put in your question, based on PLR and the coefficients you have set (derived from the literature);

$$FracFullLoadPower= C1 + C2 \cdot PLR + C3 \cdot PLR^2 + C4 \cdot PLR^3$$

Then the power consumed by the pump is calculated:

$$Power = FracFullLoadPower * NomPowerUse$$

Where NomVolFlowRate and NomPowerUse are nominal = Design values you have entered in your pump object, respectively the Design Maximum Flow Rate and Design Power Consumption fields.

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