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RE: [EnergyPlus_Support] Re: Cooling set-point not fully achieved
If you are losing control during a certain period of the year that differs from when *the* design day is occurring, then the problem can often be solved by adding extra design days for those times of the year. EnergyPlus can use many different design days and will pick the largest results for sizing.
For example, we very often find that a mid-summer design day isn't always the most stringent for cooling because during fall the lower sun angles lead to larger solar loads. In this case, adding a design day in September or October can solve the problem.
________________________________
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of anarui.oliveira
Sent: Wednesday, February 06, 2008 10:16 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: Cooling set-point not fully achieved
OK, then it goes like this (apparently, the catch was in sizing the
water flows):
- basically, I increased these "a lot" and looked at the reported
maximum flows
- the reported maximum flow, (with a large maximum design flow, which
indeed solves the set-point problem) was, not 2, but about 4 times
larger than the auto-size maximum water flow;
- which strikes me as odd, specially because the outside temperatures
in the simulation period are between 7 and 10 ºC lower than the given
design day;
In any case, the problem is located and solved. Thanks for the
guidance.
An additional, unrelated question: if the pump if PUMP:CONSTANT
SPEED, shouldn't the water flow graphics be "square-like"?
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
>
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