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Re: [EnergyPlus_Support] Fan Power modeling in Energy Plus



To answer your question 2, always use Total static pressure (TSP) and NOT External static pressure (ESP).
You should make a habit of requesting that the MEP includes BHP and TSP in their mechanical schedules.

Best,
Julien

Envoyé de mon iPhone

Le 2 oct. 2017 à 18:29, Javed Iqbal eee.javed@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> a écrit :

 

Hi,

You should use fan BHP for the energy cost calculations. To achieve the desired fan power, there are some ways of doing this based on individual preferences:
  1. Keep other parameter fix and change one perhaps total fan efficiency
  2. give PowerperFlow (W/m3/sec) input based on data sheet. Make sure the fan flow is hard sized. see below<image.png>
Hope this helps!!


On Fri, Sep 29, 2017 at 10:26 PM, fer.ricardo1@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
 

Hello, everyone.


I had an audit questioning of a certifying entity regarding the fan power output in Energy Plus, which is smaller than the fan power provided by the manufacturer data. Energy Plus simulation output shows the “Rated fan power” that considers the airflow, pressure and efficiency. Therefore, fans will consume power based on the flow and pressure under which a device operates, follow the equation:


Rated Fan Power [W] = (Airflow [m³/h] * Pressure [Pa]) / (Fan Efficiency [%])


If I use the values of Airflow, Fan Total Efficiency and Fan Pressure of the fan that I’m modeling in the Energy Plus input, the Rated Fan Power calculated by Energy Plus is usually smaller than the Nominal Power provided by the manufacturer data.


I have two questions regarding this subject:

1-) Should I modify the values of pressure and/or fan total efficiency so the rated fan power showed by Energy Plus match the nominal power provided by the manufacturer data? Or should I use the right values of these input data, as usually the nominal power provided by manufacturers usually are oversized compared to what fan actually consumes?

2-) Should I use the external static pressure provided by the manufacturer data, or should I use the total pressure drop, adding the pressure drop of the serpentine and the filter used by the equipment?


Thanks.





--


Javed Iqbal, LEED AP, CEA
Sr. Energy Analyst 



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Posted by: Julien Marrec <julien.marrec@xxxxxxxxx>


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