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Re: [EnergyPlus_Support] Re: Zone components of a 2-pipe system?
> 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@xxxxxxxx
The primary EnergyPlus web site is found at:
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The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
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