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Re: [EnergyPlus_Support] Re: Electric Chiller: air cooled
Even a constant volume plant should shut down when there is no call for
cooling. Are you sure there is no flow through any of the cooling coils?
Is the demand side bypass pipe flow rate EQUAL to the supply side flow
rate at these times? If there is no flow through any cooling coils and
the demand bypass is equal to the supply flow rate (these are the first
checks to be verified), then submit your file to the EnergyPlus Support
Group for further study.
Elmer Morrissey wrote:
> Hi,
>
> That makes sense. I had a constant volumetric flow rate, so even
> though the unit was not required to do any work (the cooling coil's
> operations was never requested), the system WAS requesting 7C at the
> outlet of the loop year round.
>
> I scheduled this loop to off during the winter months. This took
> care of the errors however I noticed that there is still a flow
> through the system!!!? Any idea why this would remain operating?
>
> However, I still have two issues with the system.
>
> (1) In the summer, the system is not pulling the cooling coil air
> outlet node temp to 12C. It gets close, but never all the way during
> peak times. The system if fully autosized..
>
> (2) The .err file says that "Loads Initialization did not Converge
> (CheckWarmupConvergence)"
>
> I've tried increasing the warmup days to 40 but this doesn't seem to
> have an effect.
>
> Kind regards
>
> -Elmer
>
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad
> <RRaustad@...> wrote:
> >
> > The message is warning you that an "air cooled" chiller is
> operating
> > when outdoor temperatures are below 0C. This type of operation
> could
> > freeze the chiller barrel and damage the unit. Good thing it is
> only a
> > simulation. What type of loads are in your building that require
> cooling
> > when it is 0C outside? How about scheduling you chiller off in the
> > winter and using an economizer.
> >
> >
> > Elmer Morrissey wrote:
> >
> > > Hello all,
> > >
> > > I'm am getting the following error from an electric chiller (air
> > > cooled) which supplies the cool water at 7C for the cooling coil
> in
> > > the AHU...
> > >
> > > ElectricChillerModel:Air Cooled Condenser Inlet Temperature
> below 0C
> > > continues
> > >
> > > Can anyone point me where I would remove this error?
> > >
> > > My chiller definition looks like this
> > >
> > > CHILLER:ELECTRIC,
> > > Z1:Plant1, !- Chiller Name
> > > AIR COOLED, !- Condenser Type
> > > autosize, !- Nominal Capacity {W}
> > > 3.2, !- COP
> > > Z1:Plant1In, !- Plant_Side_Inlet_Node
> > > Z1:Plant1Out, !- Plant_Side_Outlet_Node
> > > ZC1:Plant1In, !- Condenser_Side_Inlet_Node
> > > ZC1:Plant1Out, !- Condenser_Side_Outlet_Node
> > > 0, !- Minimum Part Load Ratio
> > > 1, !- Maximum Part Load Ratio
> > > 0.65, !- Opt Part Load Ratio
> > > 35, !- Temp Design Condenser Inlet {C}
> > > 2.778, !- Temp Rise Coefficient
> > > 6.67, !- Temp Design Evaporator Outlet {C}
> > > autosize, !- Design Evaporator Volumetric
> Water
> > > Flow Rate {m3/s}
> > > autosize, !- Design Condenser Volumetric Water
> > > Flow Rate {m3/s}
> > > 0.9949, !- Coefficient1 of the capacity
> ratio
> > > curve
> > > -0.045954, !- Coefficient2 of the capacity
> ratio
> > > curve
> > > -0.0013543, !- Coefficient3 of the capacity
> ratio
> > > curve
> > > 2.333, !- Coefficient1 of the power ratio
> curve
> > > -1.975, !- Coefficient2 of the power ratio
> curve
> > > 0.6121, !- Coefficient3 of the power ratio
> curve
> > > 0.03303, !- Coefficient1 of the full load
> ratio
> > > curve
> > > 0.6852, !- Coefficient2 of the full load
> ratio
> > > curve
> > > 0.2818, !- Coefficient3 of the full load
> ratio
> > > curve
> > > 5, !- Temp Lower Limit Evaporator
> Outlet
> > > {C}
> > > ConstantFlow; !- Chiller Flow Mode
> > >
> > > I've attempted reducing the design inlet temperature into the
> > > condenser but it doesn't appear to be making a difference. Also
> the
> > > cooling coil is not reducing the temperature of the outlet air
> > > stream to the desired temp of 12C. It gets close (13C) but never
> > > quite down there at peak times.
> > >
> > > I appreciate the help, kind regards
> > >
> > > -Elmer
> > >
> > >
> > >
> > >
> > >
> > >
> > > 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
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> > >
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> and
> > > press the "search" button.
> > >
> > >
> > >
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> > >
> > > -----------------------------------------------------------------
> -------
> > >
> >
> > --
> > 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
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
>
>
>
>
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> ------------------------------------------------------------------------
>
--
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
[Non-text portions of this message have been removed]
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