[EnergyPlus_Support] Re: how can I change the HOT WATER PLANT HW SUPPLY PUMP power in a HVAC Template

["Jean marais" <jeannieboef@xxxxxxxxx>]

Are you saying that for air fans, the field Motor Efficiency = motor eff. x fan mech eff. AND Fan Efficiency = fan mech eff. ?

This will explain why my powers are still off by a little bit.


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jim Dirkes" <jim@...> wrote:
>
> Well??
> 
> In order to calculate pump power, you must know flow, head, motor efficiency
> AND pump (mechanical) efficiency.  Since there is no input field for pump
> efficiency in E+, I looked into this a while back and the documentation
> indicated that the pump efficiency was a constant 78%.  Since you are
> indicating otherwise, I checked again and see that things appear to have
> changed!
> 
> So, is it the case that pumps now follow the E+ fan convention and use a
> combined (motor efficiency * pump mechanical efficiency) as the "Motor"
> efficiency input field?
> 
> p.s., I always thought that this was confusing, since it's not a normal
> engineering convention and the field label clearly says "Motor efficiency".
> It's workable, just confusing J.
> 
>  
> 
> The Building Performance Team
> James V. Dirkes II, P.E., BEMP , LEED AP
> 1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
> 
>  
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Richard Raustad
> Sent: Thursday, June 16, 2011 8:56 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: Re: [EnergyPlus_Support] how can I change the HOT WATER PLANT HW
> SUPPLY PUMP power in a HVAC Template System VAV
> 
>  
> 
>   
> 
> The pump efficiency is not actually used in the calculation but it is
> calculated internally to provide warnings for the user. The Engineering
> Reference shows the pertinent calculations for the pump (search for
> "Variable Speed Pump" or "Constant Speed Pump").
> 
> The calculation for pump efficiency is:
> 
> TotalEffic =   PumpEquip(PumpNum)%NomVolFlowRate *
> PumpEquip(PumpNum)%NomPumpHead  / PumpEquip(PumpNum)%NomPowerUse
> 
> PumpEquip(PumpNum)%PumpEffic =  TotalEffic / PumpEquip(PumpNum)%MotorEffic
> 
> 
> On 6/15/2011 7:31 PM, Jim Dirkes wrote: 
> 
>   
> 
> .. and E+ always assumes pump efficiency to be a constant value (78% I
> think.)
> 
>  
> 
> The Building Performance Team
> James V. Dirkes II, P.E., BEMP , LEED AP
> 1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
> 
>  
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jason Kirkpatrick
> Sent: Wednesday, June 15, 2011 6:57 PM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: Re: [EnergyPlus_Support] how can I change the HOT WATER PLANT HW
> SUPPLY PUMP power in a HVAC Template System VAV
> 
>  
> 
>   
> 
> Jose,
> 
> You can modify the pump power by changing the pump rated head in the
> HVACTemplate:Plant objects that you need to include to create the chilled
> water, hot water, and condenser water loops.
> 
> Pump Electric Power = Pump Volume Flow Rate  x  Pump Head /  Total Pump
> Efficiency
> 
> Refer to the EngineeringReference.pdf documentation that came with your
> install of energyplus for more detail.
> 
> Alternatively, once you have an expanded input data file that works, you
> could directly input the rated power consumption into the pump object and
> autosize the pump head. 
> 
> In order to accomplish this you will need to rename the file that end with
> .expidf to a file with name .idf and then you can edit and run the expanded
> idf like any other input file.
> 
> Hope this is of help.
> 
> Jason
> 
> 2011/6/14 José Ernesto Castillo Peralta <joercape@...>
> 
>   
> 
> Hi,
> 
> how can I change the power of the HOT WATER PLANT HW SUPPLY PUMP, CHILLED
> WATER PLANT CHW SUPPLY PUMP and CHILLED WATER PLANT CNDW SUPPLY PUMP in a
> HVAC Template System VAV
> 
> -- 
> 
>  
> 
> Jose Ernesto Castillo Peralta
> 
>  
> 
>  
> 
>  
> 
> 
> 
> 
> 
> -- 
> 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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