Unmet Hours - RSS feedhttps://unmethours.com/questions/Question-and-Answer Resource for the Building Energy Modeling CommunityenFri, 16 Aug 2019 02:53:53 -0500Pumps in EnergyPlushttps://unmethours.com/question/39764/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 + C2*PLR + 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,
Thu, 25 Jul 2019 09:57:13 -0500https://unmethours.com/question/39764/pumps-in-energyplus/Answer by Julien Marrec for <p>Hi,</p>
<p>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:</p>
<p>FractionFullLoadPower = C1 + C2<em>PLR + C3</em>(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. </p>
<p>Thanks,</p>
https://unmethours.com/question/39764/pumps-in-energyplus/?answer=39975#post-id-39975I think you may have just read the Input/Output Reference guide for [Pump:VariableSpeed](https://bigladdersoftware.com/epx/docs/9-1/input-output-reference/group-pumps.html#field-coefficient-1-of-the-part-load-performance-curve), because the Engineering reference for [Variable Speed Pumps](https://bigladdersoftware.com/epx/docs/9-1/engineering-reference/pumps.html#variable-speed-pump) 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](https://bigladdersoftware.com/epx/docs/9-1/input-output-reference/group-pumps.html#field-design-maximum-flow-rate) and [Design Power Consumption](https://bigladdersoftware.com/epx/docs/9-1/input-output-reference/group-pumps.html#field-design-power-consumption) fields.
Fri, 16 Aug 2019 02:53:53 -0500https://unmethours.com/question/39764/pumps-in-energyplus/?answer=39975#post-id-39975