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[EnergyPlus_Support] Re: Pump Power calculations
Dear Richard,
Thank you for the additional info.
Clarification: Is the "0.78d0" below really just 0.78, or is it
something else? If it's 0.78, is that the assumed mechanical
efficiency of the pump?
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad
<RRaustad@...> wrote:
>
> Because I left out 1 important equation:
>
> TotalEffic = 0.78d0 * PumpEquip(PumpNum)%MotorEffic
>
>
> JV Dirkes II wrote:
> >
> > Dear E+ Forum,
> >
> > I've got the pump power equation figured out and am now trying to
> > reconcile the data in .eio with my calcs.
> >
> > Per .eio:
> > Rated Volumetric Flow Rate [m3/s] .0130493
> > Rated Power Consumption [W] 5041.09232
> >
> > My calcs say it should be:
> > .0130493 * 301322 = 3,932W (Note that efficiency = 1)
> >
> > Why is there a difference?
> >
> > PUMP:VARIABLE SPEED,
> > HtgWtr Pump_1, !- Pump Name
> > NodeIn_HtgWtr Pump_1, !- Inlet_Node
> > NodeIn_Boiler1, !- Outlet_Node
> > Autosize, !- Rated Volumetric Flow Rate {m3/s}
> > 301322, !- Rated Pump Head {Pa}
> > Autosize, !- Rated Power Consumption {W}
> > 1, !- Motor Efficiency
> > 0, !- Fraction of Motor Inefficiencies to
> > Fluid Stream
> > -0.006429, !- Coefficient1 of the Part Load
> > Performance Curve
> > 1.362214, !- Coefficient2 of the Part Load
> > Performance Curve
> > -0.348214, !- Coefficient3 of the Part Load
> > Performance Curve
> > 0, !- Coefficient4 of the Part Load
> > Performance Curve
> > 0, !- Min Flow Rate while operating in
> > variable flow capacity {m3/s}
> > CONTINUOUS, !- Pump Control Type
> > SchCpct_AlwaysOn; !- Pump Flow Rate Schedule Name
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > <mailto:EnergyPlus_Support%40yahoogroups.com>, "JV Dirkes II"
<jvd2pe@>
> > wrote:
> > >
> > > Dear Richard,
> > >
> > > So, pardoning my ignorance of SI, if
> > > %Power = %Head x %NomFlowRate / Eff
> > > does that mean that m3/s x Pa = W ?? (i.e., no units conversion
> > > constant? That doesn't seem right...)
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > > <RRaustad@> wrote:
> > > >
> > > > Straight out of the sizing routine...
> > > >
> > > > PumpEquip(PumpNum)%NomPowerUse =
> > > (PumpEquip(PumpNum)%NomPumpHead
> > > > * PumpEquip(PumpNum)%NomVolFlowRate) / TotalEffic
> > > >
> > > >
> > > > JV Dirkes II wrote:
> > > > >
> > > > > Dear E+ Forum,
> > > > >
> > > > > For ASHRAE 90.1 baseline models, a pump is limited to a specific
> > unit
> > > > > power (e.g., 22W / gpm for chilled water pumps). I want to
autosize
> > > > > the pumps, but use a Delta P and motor efficiency that will
always
> > > > > result in the desired unit power. My derivation of that Delta P
> > value
> > > > > does NOT result in the power level that I expect when I run
E+. So,
> > > > > either my derivation is incorrect, or E+ calculates the
power in a
> > > > > different manner.
> > > > > Will someone direct me to the E+ power formula for situations
> > when the
> > > > > pump is autosized? I must be missing something, but cannot find
> > it in
> > > > > "Help". Thanks!
> > > > >
> > > > >
> > > >
> > > > --
> > > > Richard A. Raustad
> > > > Senior Research Engineer
> > > > Florida Solar Energy Center
> > > > University of Central Florida
> > > > 1679 Clearlake Road
> > > > Cocoa, FL 32922-5703
> > > > Phone: (321) 638-1454
> > > > Fax: (321) 638-1439 or 1010
> > > > Visit our web site at: http://www.fsec.ucf.edu
> > <http://www.fsec.ucf.edu>
> > > >
> > > > UCF - From Promise to Prominence: Celebrating 40 Years
> > > >
> > >
> >
> >
>
> --
> Richard A. Raustad
> Senior Research Engineer
> Florida Solar Energy Center
> University of Central Florida
> 1679 Clearlake Road
> Cocoa, FL 32922-5703
> Phone: (321) 638-1454
> Fax: (321) 638-1439 or 1010
> Visit our web site at: http://www.fsec.ucf.edu
>
> UCF - From Promise to Prominence: Celebrating 40 Years
>
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