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Re: [EnergyPlus_Support] Re: Cooling set-point not fully achieved
What you describe is not a capacity issue, it is related to the
prediction of loads. If you add the report variable for "Zone/Sys
Sensible Load Predicted" and set the report variable frequency to
detailed, you will see why this is happening. Try reducing the Minimum
System Time Step in the System Convergence Limits object. You probably
will not eliminate the problem, but it should get better.
anarui.oliveira wrote:
>
> What if, in a similar (heating) case, water flow doesn't reach the
> maximum when the problem occurs, and increasing the air flow causes
> further departure from temperature setpoint?...(Less than about 1.5
> times the auto-sized air flow also leads to poorer setpoint
> tracking); reported air flow is always equal to the constant volume
> fan flow, and ouside air flow rate is (and must be) user specified.
>
> Regards,
> Ana.
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> <RRaustad@...> wrote:
> >
> > Then try again to manually size the coil in the problem zone to
> twice
> > the size reported in the eio file. Also increase the air flow rate
> for
> > that fan coil unit and fan to twice the autosized value. If htis is
> > happening in more than 1 zone, then just pick 1 for now to test
> this out.
> >
> > Then tell me what happens to the maximum zone temperature. Did the
> > maximum zone temperature go down? Also tell me if the water flow
> rate is
> > at a maximum when the zone temperature exceeds the set point. You
> can
> > report "System Node VolFlowRate" for the coil water inlet node and
> fan
> > coil air inlet node to easily match volumetric flow rate with your
> inputs.
> >
> > This just sounds like a sizing issue and should be easily resolved.
> >
> > anarui.oliveira wrote:
> > >
> > > Apparently, yes, but I set it to autosize (and I think I already
> did
> > > a trial with a larger, user-defined, water flow rate)...
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> > > <RRaustad@> wrote:
> > > >
> > > > I have not looked at your input file, can you tell me if the
> water
> > > mass
> > > > flow rate through the fan coil is at a maximum when the cooling
> set
> > > > point is not met?
> > > >
> > > > anarui.oliveira wrote:
> > > > >
> > > > > Please forgive me for insisting, but I DO have some urgency on
> > > this
> > > > > one...
> > > > > Again, thanks for any help,
> > > > > Ana.
> > > > >
> > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > > <mailto:EnergyPlus_Support%
> 40yahoogroups.com>, "anarui.oliveira"
> > > > > <anarui.oliveira@> wrote:
> > > > > >
> > > > > > Hi again.
> > > > > >
> > > > > > I'm uploading a new file (Zone36598_cFancoil_exp), hoping
> that
> > > > > someone
> > > > > > can help me figure out why the cooling setpoints are not
> being
> > > > > achieved
> > > > > > for all times when the controls are active (namely in Zone
> > > 36598).
> > > > > The
> > > > > > model consists of Fancoil units created with Compact HVAC,
> and
> > > then
> > > > > > edited in the expanded file.
> > > > > > I tried several user-defined and sizing options, but
> couldn't
> > > solve
> > > > > the
> > > > > > temperature peaks above 25ºC.
> > > > > >
> > > > > > Thanks in advance,
> > > > > > Ana Rui.
> > > > > >
> > > > >
> > > > >
> > > >
> > > > --
> > > > 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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