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[EnergyPlus_Support] Re: Zone components of a 2-pipe system?
In case anyone else is interested in similar modelling, Compact HVAC
also duplicates zone thermostatic controls, so one (per zone) must
be deleted and there's some minor node connection adjustments to be
done, but it was fairly simple and it worked beatifully.
I had values to define the HVAC components, but if I wanted to auto-
size, given the issue you mentioned, what would you suggest
(priority 1 to Direct Air and priority 2 to FanCoil)?
Thanks,
Ana.
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte"
<mjwitte@...> wrote:
>
> > Another question, to add to the previous:
> > - The Compact HVAC approach doesn't let us define both a
Zone:VAV and
> > a FanCoil? (I get errors about duplicate Zone sizing objects...)
>
> That is correct. Compact HVAC currently supports only one system
per zone.
> But the workaround is fairly straightforward, unless you have a
large number of
> zones.
>
> 1. Using the idf file you have already created, take the expidf
output file
> and save it to a new name as .idf
>
> 2. For each zone served by the vav and fan coil, delete one of
the ZONE SIZING
> objects. Note that EnergyPlus sizing does not recognize that
there are two
> systems serving a zone - it will try to size both system to meet
the full load,
> but that's another issue. Let's get this file running first.
>
> 3. For each zone served by the vav and fan coil, there are also
duplicate
> CONTROLLED ZONE EQUIP CONFIGURATION and ZONE EQUIPMENT LIST
objects. You must
> merge these objects into one of each for each zone. The final
CONTROLLED ZONE
> EQUIP CONFIGURATION object will have 2 zone inlet nodes, a zone
air node, one
> exhaust node, and one return node. In order to specify 2 inlet
nodes, you will
> need to create a NODE LIST object which lists the two inlets and
then use the
> NODE LIST name in the CONTROLLED ZONE EQUIP CONFIGURATION object.
>
> With these changes, the file should run.
>
> Mike
>
> On 4 Feb 2008 at 16:15, anarui.oliveira wrote:
>
> > Another question, to add to the previous:
> > - The Compact HVAC approach doesn't let us define both a
Zone:VAV and
> > a FanCoil? (I get errors about duplicate Zone sizing objects...)
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "anarui.oliveira"
> > <anarui.oliveira@> wrote:
> > >
> > > Thanks a lot.
> > >
> > > The Central AHU has a heat recovery component, which receives
the
> > > return airflow from more than 1 zone, so I think I should keep
the
> > > two levels of the heating/cooling process?...as opposed to
letting
> > > the fan-coils addressing the full thermal load?...
> > > In this case, it appears it wouldn't actually be easier to
treat
> > the
> > > heat recovery by "manual" post-processing?...Or are there any
known
> > > downsides to this two-level approach?
> > >
> > > At the moment, is there any approach in E+ that would
accurately
> > > mimic the system I described? I mean, could I actually (with
nore
> > or
> > > less "manual work"), set up both a heating and a cooling coil
to
> > act
> > > on the supply air, at zone level, setting both coils operation
to
> > > depend on the zone thermostat (at the moment, I don't really
need
> > > many details on this, I would just like to know the
possibilities)?
> > >
> > > Again, thanks a lot,
> > > Ana Rui.
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte"
> > > <mjwitte@> wrote:
> > > >
> > > > If I am understanding the system correctly, the simplest
approach
> > > would be to
> > > > use the 4-pipe fan coil with mutually exclusive schedules
for the
> > > heating and
> > > > cooling coils. However, do not set the inlet conditions to
be
> > from
> > > the central
> > > > ahu, simply let the fancoil unit carry the entire load.
> > > >
> > > > It is not clear to me whether it matters that the
heaitng/cooling
> > > be modeled in
> > > > two parts. If it does matter, then I would still use the 4-
pipe
> > > fan coil, but
> > > > with no outside air. And then describe a constant volume
air
> > loop
> > > which
> > > > delivers the partially conditioned outside air using a
direct air
> > > terminal unit
> > > > in each zone. If the direct air unit is listed with heating
and
> > > cooling
> > > > priority 1, then the fan coil will pick up any remaining
load.
> > > >
> > > > Mike
> > > >
> > > >
> > > > On 26 Jan 2008 at 17:03, anarui.oliveira wrote:
> > > >
> > > > > Hello, all.
> > > > >
> > > > > I'm having a hard time to figure out the best options to
model
> > a
> > > > > specific 2-pipe HVAC configuration...
> > > > >
> > > > > Any ideas about which could be the simplest way to
approximate
> > > the
> > > > > zone level model of a 2-pipe (constant volume) system with:
> > > > > - an AHU that delivers 100% OA at inermediate
heated/cooled
> > > > > temperatures (18/27 ºC) to the zone level,
> > > > > - where a battery with either hot or chilled water coil
> > (mutually
> > > > > exclusive at any given moment, and necessarily in the same
> > > operation
> > > > > regime - heating or cooling - serving the central AHU)
meets
> > the
> > > > > additional load (when needed),
> > > > > - raising/decreasing the air temperature of the supply air
loop
> > > to
> > > > > design Temperatures of 35ºC(heating) or 16ºC (cooling), to
meet
> > > Room
> > > > > Air setpoint conditions according to a 20-25ºC thermostat?
> > > > >
> > > > > The "Single Duct:Const Volume: Reheat" and "Single
Duct:Const
> > > Volume:4
> > > > > pipe" don't quite seem to reproduce this behaviour?...
> > > > >
> > > > > No recirculating or induced air from the room actually
happens
> > in
> > > the
> > > > > real situation (the zone level re-conditioning is
performed
> > > directly
> > > > > and uniquely in the air supplied by the AHU, and then
delivered
> > > to the
> > > > > room, where the mixed model should take care of the
rest)...
> > > > > ...but perhaps, in terms of global thermal loads and
energetic
> > > > > analysis, it wouldn't be too far fetched to use
> > > > > - "Single Duct:Const Volume:4 pipe"
> > > > > or
> > > > > - "direct air" and "fan coil: 4 pipe"
> > > > > with mutually exclusive availability schedules for the
coils
> > and
> > > > > design air inlet temperatures equal to the setpoints of
AHU
> > > supply
> > > > > air?...
> > > > > ... the main differences between these options being?...
> > > > >
> > > > > Better options?...
> > > > >
> > > > > Thanks in advance,
> > > > > Ana Rui.
> > > > >
> > > > >
> > > > >
> > > > > 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
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > > > ========================================================
> > > > Michael J. Witte, GARD Analytics, Inc.
> > > > EnergyPlus Testing and Support
> > > > EnergyPlus-Support@
> > > >
> > >
> >
> >
> >
> >
> > 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
> >
> >
> >
> >
> >
>
>
> ========================================================
> Michael J. Witte, GARD Analytics, Inc.
> EnergyPlus Testing and Support
> EnergyPlus-Support@...
>
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