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[EnergyPlus_Support] Re: Combination of the OA unit system and Fancoil unit system
Thanks very much,Mike.I will have a try according to your suggestion.
pch
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte"
<mjwitte@g...> wrote:
>
> If I understand the system correctly, this is very much like a 4-
pipe induction
> unit. There is central outside air which is preconditioned, then
this air is
> mixed with zone air and conditioned by heating/cooling coils in the
zone
> (fancoil unit). I would recommend using SINGLE DUCT:CONST VOLUME:4
PIPE INDUC,
> see 5ZoneFPIU.idf example file. In your case, the central unit is
100% outside
> air. EnergyPlus requires a return path in this case, even though
all of the
> "return air" will become "relief air" (exahusted) at the outside
air mixing
> box. (Note that HVAC Diagram is unable to draw this type of system.)
>
> Mike
>
>
> On 18 Oct 2005, at 11:01, hbn_pch wrote:
>
> > Thanks for your response,Mike.According to your suggestion,i have
> > modified the model.Waiting and appreciated your further response.
> >
> > Now i have a expanded issue for the model.In the original
model,the
> > oa unit supply air to the zone directly.In reality,i want to mix
the
> > oa system supply air and the zone exhaust air.The mixed air will
be
> > cooled/heated by fancoil unit and then supplied to zone.But i
don't
> > know how to connect the nodes.In fact,there is no return air for
the
> > oa unit.I'm puzzled.
> >
> > I have a supposition that i can divided the model into two single
> > models.
> > The first:fancoil units serve zone only.In this case,i tried to
set
> > the outside air temp of the fancoil to 14(cooling supply temp)or
50
> > (heating supply temp).It seems that the outside air of fancoil is
> > just the oa supply air.(In fact,there is no outside air specified
for
> > fancoil unit).The problem is that i can't find a approach to
specify
> > the fancoil outside air inlet temp.Can it be specified?
> > The second model:outside air unit serve zone only.
> >
> > Then i can combine the two models for analysis.I don't know
whether
> > it is available.If yes,how to specify the outside air inlet temp
for
> > the fancoil?If no,can you give me a correct approach?
> >
> > Thanks in advance.
> > pch
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte"
> > <mjwitte@g...> wrote:
> > >
> > > Whenever there is a sizing question, the first place to look is
in
> > the eio
> > > output file at the sizing reports. One this to note (which is
not
> > discussed in
> > > the Input Output Reference) is that the sizing algorithms do no
> > know how to
> > > split loads between multiple systems. Each system serving a
zone
> > will be sized
> > > to meet the full load of the zone. For this system type to
work,
> > you will
> > > probably need to specify the supply air flow rate for one
system or
> > the other.
> > > Some issues I've noticed so far:
> > >
> > > 1. The coil component sizing report lists "COIL:Water:Cooling,
> > RESISTIVE
> > > ZONE_FANCOILCOOLINGCOIL, Design Air Inlet Temperature [C],
> > 13.000" and
> > > "Design Air Outlet Temperature [C], 14.000". This is why the
> > coil water flow
> > > is sizing to zero. The 13C inlet temperature is coming from
the
> > SYSTEM SIZING
> > > object - this appears to be a program error. I will ask
someone
> > else to look
> > > at this more closely. Changing the SYSTEM SIZING cooling
supply
> > air
> > > temperature to 15C allows the run to continue past this point.
> > >
> > > 2. The CONTROLLER:OUTSIDE AIR, OA CONTROLLER, minimum outside
air
> > flow rate
> > > [m3/s] is 0.0000. There is no outside air in the OA system.
The
> > ZONE SIZING
> > > objects indicate an outside air flow per person, but there are
no
> > PEOPLE
> > > objects, so this becomes zero.
> > >
> > > Mike
> > >
> > >
> > > On 17 Oct 2005, at 9:14, hbn_pch wrote:
> > >
> > > > Dear,
> > > > Cry!
> > > > According to above two issues,i test more and more time.I
> > tried to
> > > > change the priority of the OA unit and FanCoil unit.But i
found
> > the
> > > > fancoil did't work yet.It also appeared that the design coil
load
> > is
> > > > zero for cooling coil and heating coil in the zone fancoil
unit.
> > > > Now i really don't know how to fix the problem.
> > > >
> > > > Waiting your kind help.thanks very very much.
> > > > pch
> > > >
> > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "hbn_pch"
> > <hbn_pch@y...>
> > > > wrote:
> > > > >
> > > > > Hi,
> > > > > I'm sorry that i had another doubt.If all element are
> > > > autosized,it
> > > > > seems that the oa unit always trid to meet the load because
of
> > its
> > > > > high priority for heating and cooling.And then all of the
> > fancoil
> > > > > unit will not work at all.Is it right?But the real
anticipant
> > > > result
> > > > > is : oa unit tried to meet load first,and if it could't
> > produced
> > > > > adequate energy,then fancoil will try to meet excess
load.How
> > to
> > > > > realize above controlld operation??
> > > > >
> > > > > Thanks very much! appreciated your kind help.
> > > > >
> > > > > pch
> > > > >
> > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "hbn_pch"
> > <hbn_pch@y...>
> > > > > wrote:
> > > > > >
> > > > > > Dear sir,
> > > > > > I created a 3-zone model.Each zone has own fancoil
unit to
> > > > serve
> > > > > > and there is a indepent outside air unit to serve the
three
> > > > > > zones.Fancoil units specifies no outside air(maximum
outside
> > air
> > > > > rate
> > > > > > set to 0),and their cooling source is a chiller,heating
> > source is
> > > > > > purchased heating.
> > > > > > The OA unit used another purchased cooling and purchased
> > heating
> > > > as
> > > > > > its cooling&heating source. The OA unit had high priority.
> > > > > >
> > > > > > After simulation,there are some warnings and severes as
> > follows:
> > > > > >
> > > > > > ** Warning ** The design coil load is zero for
> > > > > COIL:Water:Cooling
> > > > > > RESISTIVE ZONE_FANCOILCOOLINGCOIL
> > > > > > ** ~~~ ** The autosize value for max water flow
rate
> > is
> > > > zero
> > > > > > ** Warning ** The design coil load is zero for
> > > > > COIL:Water:Cooling
> > > > > > EAST ZONE_FANCOILCOOLINGCOIL
> > > > > > ** ~~~ ** The autosize value for max water flow
rate
> > is
> > > > zero
> > > > > > ** Warning ** The design coil load is zero for
> > > > > COIL:Water:Cooling
> > > > > > NORTH ZONE_FANCOILCOOLINGCOIL
> > > > > > ** ~~~ ** The autosize value for max water flow
rate
> > is
> > > > zero
> > > > > > ** Warning ** Check input. Pump nominal power or motor
> > > > > efficiency
> > > > > > is set to 0, for pump=CW PUMP
> > > > > > ** Warning ** Check input. Pump nominal volumetric
flow
> > rate
> > > > is
> > > > > > set or calculated = 0, for pump=CW PUMP
> > > > > > ** Warning ** Check input. Pump nominal power or motor
> > > > > efficiency
> > > > > > is set to 0, for pump=OA HW PUMP
> > > > > > ** Warning ** Check input. Pump nominal volumetric
flow
> > rate
> > > > is
> > > > > > set or calculated = 0, for pump=OA HW PUMP
> > > > > > ** Warning ** Check input. Pump nominal power or motor
> > > > > efficiency
> > > > > > is set to 0, for pump=COND PUMP
> > > > > > ** Warning ** Check input. Pump nominal volumetric
flow
> > rate
> > > > is
> > > > > > set or calculated = 0, for pump=COND PUMP
> > > > > > ** Severe ** COOLING TOWER:SINGLE SPEED "CENTRAL
COOLING
> > > > > TOWER".
> > > > > > Free convection air flow rate must be less than the
design
> > air
> > > > flow
> > > > > > rate.
> > > > > > ** Severe ** COOLING TOWER:SINGLE SPEED "CENTRAL
COOLING
> > > > > TOWER".
> > > > > > Free convection UA must be less than the design tower UA.
> > > > > >
> > > > > > It seems that the oa unit has produced adequate energy
and
> > the
> > > > > > fancoil units did't need to work(Is it right???).But
there is
> > a
> > > > > > problem for the OA HW Pump,it did't work at all.The
cooling
> > tower
> > > > > > did't work yet.Why????
> > > > > >
> > > > > > In ordoer to urge the oa unit and fancoil unit working
> > > > together,i
> > > > > > tried to reduce the zone sizing temp from 14 to 4.And two
> > units
> > > > > work
> > > > > > together as anticipant.Only leaving warnings of the OA HW
> > > > Pump.But
> > > > > > changing the zone sizing temp to 4 is illogical,then what
can
> > i
> > > > > do???
> > > > > >
> > > > > > All of values are autosized.Can i specify the load
produced
> > by
> > > > oa
> > > > > > unit(eg.specify maximum air flow rate of the direct air
> > unit),and
> > > > > > auotsize the fancoil unit to decide their on/off????
> > > > > >
> > > > > > I don't know whether the combination of the two unit
system
> > is
> > > > > > correct.I hope somebody can help me.Thanks very much.
> > > > > > I've upload the file(pch.idf) to file area.
> > > > > >
> > > > > > Thanks again.
> > > > > > pch
> > > > > >
> > > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > 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.idf
> > and press the
> > > > "search" button.
> > > >
> > > > Yahoo! Groups Links
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> > >
> > > ========================================================
> > > Michael J. Witte, GARD Analytics, Inc.
> > > EnergyPlus Testing and Support
> > > EnergyPlus-Support@g...
> > >
> >
> >
> >
> >
> >
> >
> >
> > 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.idf
and press the
> > "search" button.
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
>
> ========================================================
> Michael J. Witte, GARD Analytics, Inc.
> EnergyPlus Testing and Support
> EnergyPlus-Support@g...
>
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