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Re: [EnergyPlus_Support] Re: Fan Power Pressures and Efficiencies - Are the calculations based on Pstat or Pt

Why don't you enter a pressure and see if you get the power you expect?

jeannieboef wrote:
>
> That is a very circular answere that does not at all answere the 
> question. I've looked the documentation and it is not clear which is 
> the input, static pressure rise "across the fan" or dynamic pressure rise.
>
> The definition of "Supply Fan Delta Pressure" is not clear!
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad 
> <RRaustad@...> wrote:
> >
> > The value you enter in the fan object is used by E+ in the 
> calculations:
> > the equations are described in the Engineering Reference. The detlaP
> > used in those equations are the value you enter in the fan object (in
> > this case 600 Pa)
> >
> > Fan:OnOff,
> > Supply Fan 1, !- Name
> > FanAndCoilAvailSched, !- Availability Schedule Name
> > 0.7, !- Fan Efficiency
> > 600.0, !- Pressure Rise {Pa}
> >
> >
> > jeannieboef wrote:
> > >
> > > Correct, however still not clear which is used as user input and 
> which
> > > is calculated by e+.
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > > <RRaustad@> wrote:
> > > >
> > > > Total pressure.
> > > >
> > > > Ptotal = Pstatic + Pdynamic
> > > > Ptotal = Pstatic + 1/2 * rhoV^2
> > > >
> > > >
> > > > jeannieboef wrote:
> > > > >
> > > > > Are the calculations based on total pressure or static 
> pressure rise?
> > > > >
> > > > > Field: Supply Fan Total Efficiency
> > > > > Enter the total efficiency of the supply fan. This is the 
> ratio of
> > > the
> > > > > power delivered to the air to
> > > > > the electrical input power at maximum flow. This is also the 
> product
> > > > > of the fan motor
> > > > > efficiency and fan (impeller) efficiency. The motor efficiency 
> is the
> > > > > power delivered to the
> > > > > shaft divided by the electrical power input to the motor. The fan
> > > > > efficiency is the power
> > > > > delivered to the air divided by the shaft power. The power 
> delivered
> > > > > to the fluid is the mass
> > > > > flow rate of the air multiplied by the pressure rise divided 
> by the
> > > > > air density. Must be greater
> > > > > than 0 and less than or equal to 1. The default is 0.7.
> > > > >
> > > > > Field: Supply Fan Delta Pressure
> > > > > Enter the pressure rise in Pa at full flow and standard 
> conditions.
> > > > > Standard conditions are
> > > > > considered 20o C at sea level, 101325 Pa. The default is 1000 Pa.
> > > > >
> > > > >
> > > >
> > > > --
> > > > 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> <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 <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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