[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [EnergyPlus_Support] Re: Precooling chilled water return
I thought you wanted them in series, I see now you were asking about a
bypass around the smaller chiller. I can't say for sure if that will
work correctly. You will just have to try it and see. I think you need
the same number of splitters and mixers, so put a splitter at the inlet
(return) of the small chiller and a mixer at the outlet (supply) of the
small chiller and connect with a bypass pipe. Let us know if this works
correctly.
zhaicq98 wrote:
>
> Thanks Richard. I donot quite understand when you said both chillers
> will operate at the same evaporator volumeric flowrate. Can I bypass
> some of the chilled water flow around the small chiller? In this
> way, the big chiller can have a higher flow and the small chiller
> has a lower flow.
>
> Thanks again,
> Chaoqin
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> <RRaustad@...> wrote:
> >
> > This should work in E+. You would need to use constant flow
> chillers and
> > the chillers should not be auto-sized (or at least the smaller
> one). The
> > only problem I see is that you can not have a significant
> difference in
> > the capacities of the series chillers. The reason is that both
> chillers
> > will operate at the same evaporator volumetric flow rate (and the
> > performance curves should account for off-design flow rates).
> There is
> > an upper (and lower) limit to the water velocities through a
> chiller's
> > heat exchanger. Above the upper limit, erosion of heat exchanger
> will be
> > excessive (and so will the pressure drop). Below the lower limit
> there
> > is a chance of freezing the heat exchanger or reducing oil
> transport
> > through the refrigeration system. Of course this will not hurt the
> > simulation, but you want to be as close to reality as possible.
> And if
> > you actually built a chiller with an over-sized heat exchanger,
> you
> > would not have this problem. Check with manufacturers for
> appropriate
> > ranges of water flow rates through the evaporators for your type
> of
> > chiller. The same holds true for the condenser heat exchangers,
> but you
> > could pipe the condensers in parallel.
> >
> > zhaicq98 wrote:
> > >
> > > I have a big and a small water cooled vapor compression chiller
> in the
> > > system. They are configured in series, but the chilled water
> flowrate
> > > of the
> > > big chiller is much greater than the small one. The small
> chiller is
> > > used to
> > > pre-cool a portion of the chilled water return to the big
> chiller.
> > >
> > > I wonder if EnergyPlus is able to handle this system. Thanks for
> your
> > > help.
> > >
> > > -Chaoqin
> > >
> > >
> >
> > --
> > 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/