[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[EnergyPlus_Support] Re: Condenser Water Plant - 4 Two-Speed Cooling Towers Parallel+Headered Pumps
Dear Richard,
Thank you very much for your immediate response.
I have tried once more to model a headered pump object in lieu of a variable speed pump in my condenser loop. I have also verified that it is the very first object in the condenser loop ("Supply Inlet Branch") and received the proper node declaration. Unfortunately and once more the simulation terminated with a fatal error:
** Fatal ** SimCondEquip: Invalid Equipment type requested=HEADEREDPUMPS:CONSTANTSPEED
...Summary of Errors that led to program termination:
..... Reference severe error count=0
..... Last severe error=
I don't think headered pumps can be currently modeled in a condenser loop, opposed to a chilled water loop (which works really well).
I have studied the example file "HeaderedPumpsConSpeed.idf" that specifically describes how to model a headered pump object in a chilled water loop but unfortunately does not advise on modeling a headered pump in a condenser loop. Are there any other files in this specific regard I should pay attention to and what are their dedicated filenames?
The engineering reference still states, that a pump object can only be modeled on the supply side of a condenser loop (opposed to plant loop).
In regards to the issue of evenly diverting flow into all of the four parallel arranged cooling towers. My first attempt considered all of the four cooling towers with a description of their nominal capacity, hence it is not possible to enter a design water flow rate. I would very much like to retry once more and follow your suggestion and describe the cooling tower's capacity with "UFactorTimeAreaAndDesignWaterFlowrate" and have to rely on my best judgement when entering the remaining fields (U Factor...etc).
Thank you Richard,
Sandro
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@...> wrote:
>
> 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
>
------------------------------------
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are not allowed -- please post any files to the appropriate folder in the Files area of the Support Web Site.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/EnergyPlus_Support/
<*> Your email settings:
Individual Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/EnergyPlus_Support/join
(Yahoo! ID required)
<*> To change settings via email:
mailto:EnergyPlus_Support-digest@xxxxxxxxxxxxxxx
mailto:EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx
<*> To unsubscribe from this group, send an email to:
EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/