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Re: [EnergyPlus_Support] Condenser Water Plant - 4 Two-Speed Cooling Towers Parallel+Headered Pumps
Well actually the pump can now be on the demand or supply side of the
loop. Just make sure it's the first object. It is usually listed on the
inlet branch (either Plantloop or Condenserloop). Looking at some of the
water cooled example files may help. You can also read the description
for "Pumps" in the Engineering Reference.
Richard Raustad wrote:
>
>
> Sorry, the pump must be on the plant supply side. Check the first
> "supply" branch (see Plantloop object) and make sure the pump is listed
> on that branch.
>
> Richard Raustad wrote:
> >
> >
> > Your first attempt delivers a warning that tells you that the pump must
> > be the first object at the inlet of the plant loop. Check the demand
> > side branchlist and make sure the pump is defined on that branch.
> >
> > Your alternative of modeling 4 cooling towers in parallel may be running
> > into the fact that the cooling towers are passive devices and can handle
> > up to 2.5 times the nominal or design flow rate. You might try reducing
> > the water flow rate through each tower (by a factor of 2.5) and see if
> > that gets you the performance you are looking for.
> >
> > berlinclownfish wrote:
> > >
> > >
> > > Dear EnergyPlus-Support,
> > >
> > > I'd like to model a typical Condenser Water Plant consisting of four
> > > Two-Speed Cooling towers in a parallel arrangement and fed by a
> > > headered constant speed pump.
> > >
> > > First attempts to incorporate a headered pump object instead of a
> > > common single and constant speed condenser water pump (reflecting
> > > total volume flow rate) ended in a fatal error with the following
> > > message:"The following pump is not the first component on its
> > > loop/branch: TOWERWATERSYS1 PUMP". Did I overlook anything, possibly a
> > > mistake in node connections and declarations?
> > >
> > > As an alternative, I have modeled a single variable speed pump in an
> > > attempt to reflect a variable volume flow condenser loop depending on
> > > the demand by a set of 4 parallel Two-Speed Cooling towers.
> > > However, I was unable to divert any flow into 3 of the 4 cooling
> > > towers, irregardless of the amount of trial combinations in creating
> > > various operation schemes and branch control types. Did I possibly
> > > miss a "smart" combination.
> > >
> > > It turned out, that the very first cooling tower in the arrangement
> > > requested/received the entire amount of flow available from the
> > > variable speed pump. Replacing the condenser pump in this arrangement
> > > with a headered pump or constant speed pump was unsuccessful. By the
> > > way, a headered pump works extremely well for the staged arrangement
> > > of 4 parallel centrifugal chillers, supplying appropriate amounts of
> > > chilled water in a staged fashion.
> > >
> > > As another alternative, I attempted to model branch pumps for each
> > > cooling tower, which also did not end very well.
> > >
> > > I am well aware of simplification methods when modeling, but would
> > > like to reflect upon the free convection regime on all of the four
> > > cooling towers as realistic as possible and furthermore evaluate the
> > > option of replacing a single or two out of the four cooling towers by
> > > upgrading it to a variable speed tower, hence the effort.
> > >
> > > EnergyPlus-Users, did anyone come across this challenge and succeeded?
> > > Submitting a working reference example file would be outmost generous
> > > and I would be very thankful!
> > >
> > > Thank you,
> > >
> > > Sandro
> > >
> > >
> >
> > --
> > 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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