[EnergyPlus_Support] Re: Fan Electric Power

["anarui.oliveira" <anarui.oliveira@xxxxxxxxx>]

Sorry, could you add some legends to make sure I'm looking at the 
right variables?...
If I understood, those calculations correspond to an independent 
estimate of electric power consumption of the fans?

In the cases when I detected large differences between E+ and 
supplier data, the supplier data indicated straightforward electric 
power consumption of the fans... and delta-Pressure and nominal 
airflow. I used that dP and airflow (which does not vary 
significantly beacuse I was using CAV models) to feed to E+ and 
obtain its electric power estimate... I had also high values of 
(total) efficiency (above 0.7), but even trying to reduce those in E+ 
did not increase the power estimate to values anywhere near the 
supplier data...

I guess the supplier data may sometimes include the effect of the 
selected fans not working at nominal conditions for the intended 
aiflows, but still... differences of twice over?...

Anyway, thanks for everything,
Ana.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "JV Dirkes II" 
<jvd2pe@...> wrote:
>
> Dear Ana,
> 
> I get excellent agreement for fan power when using (US 
measurements):
> 
> BHP =    CFM x    Î"P
>                    η x    6,355
> 
> =   f3 x    in. w.c. x    62.316 lb              x     min-HP
>      min               η            ft2 x 12 in. w.c.      33,000
> ft-lb
> 
> =    CFM x     Î"P
>            η  x   6,355
> 
> It is important to know the mechanical efficiency of the fan "η"
> from a fan chart, or to derive it from known Brake HP.
> 
> Also, you must make sure that the E+ report reflects the correct 
flow. A
> relief fan, for example, may never operate at the rated airflow and 
the
> .eio report only shows Watts for the modeled airflow.  The .ssz will
> show the design airflow.
> If you are using a sizing factor greater than 1.0, don't forget to 
use
> the rated airflow x sizing factor as your basis for power 
calculations.
> 
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "anarui.oliveira"
> <anarui.oliveira@> wrote:
> >
> > Hi, me again.
> >
> > Has anyone tried to compare the E+ estimates of Fan Electric Power
> with
> > rated electric consumptions for these equipments?
> > I've been trying to "calibrate" these values, but I keep getting 
E+
> > plus estimates much lower than supplier data (like 2 to 10 times
> > smaller values, for E+ estimate of Fan electric power).
> >
> > Regards,
> > Ana Rui.
> >
>



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