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[EnergyPlus_Support] Re: Pump Power calculations
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, "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, 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
> >
> > UCF - From Promise to Prominence: Celebrating 40 Years
> >
>
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