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[EnergyPlus_Support] Re: Combination of the OA unit system and Fancoil unit system
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
> >
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> > http://groups.yahoo.com/group/EnergyPlus_Support/
> >
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> >
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> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
>
> ========================================================
> Michael J. Witte, GARD Analytics, Inc.
> EnergyPlus Testing and Support
> EnergyPlus-Support@g...
>
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