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[EnergyPlus_Support] Re: Pump and fan efficiencies

Dear Leslie,

  1. Changing efficiency of the fan does not affect flow rate.  It affects the POWER used by the fan to deliver a given flow.  Check the Engineering Reference for the power calculation.
  2. The above is also true for a pump.  In that case, your load ( and the corresponding autosized flow rate), the pump head and efficiency determine the peak power requirement.  The part load coefficients then modify the peak power.  If you change the pump efficiency, ALL pump power calcs will be affected.  (Once again, check the Engineering Reference)

So, the short answer is "YES", improving efficiency is as easy as changing the respective efficiency parameter.


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, L Herrmann <l.herrmann@...> wrote:
>
> Yes, This was informative, thank you.  Now my questions are more defined:
>
> 1. I have a variable speed fan with auto-sized min and max flow rates, and a set pressure rise of 600 Pa.  Will changing the fan efficiency (not the motor efficiency) adjust the volume flow rates accordingly or do I need to get involved with the coefficients of the 'part load factor?'
>
> 2. I have a variable speed pump also with auto-sized 'Rated flow rates' and 'Rated power consumption.' The rated pressure head is set at 179,000 Pa. The same question applies; can I increase the 'Motor efficiency' value to improve the overall efficiency of the pump or do I need to tweak the coefficient values?
>
> The general question here is: Is improving the fan and pump efficiency (not the motor efficiency) as easy as increasing the value in 'Fan efficiency' and 'Motor efficiency,' respectively?
>
> Thanks!
> Lesley
>
>
> ________________________________
> From: JV Dirkes II jvd2pe@...
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Sent: Monday, March 16, 2009 1:05:57 PM
> Subject: [EnergyPlus_Support] Re: Pump and fan efficiencies
>
>
> Did my post of earlier today not answer your question? If it did not, please clarify your question a bit. Thanks!
>
> --- In EnergyPlus_Support@ yahoogroups. com, L Herrmann <l.herrmann@ ...> wrote:
> >
> >
> >
> > I was wondering about how to adjust pump and fan efficiencies in EP.  For example, to change the efficiency of the pump motor, would one need to create an entirely new pump with a higher efficiency- which meets the flow rate and head for the system? 
> >  
> > Thanks
> >
>



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