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Re: [EnergyPlus_Support] Re: Combination of the OA unit system and Fancoil unit system



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@xxxxxxxx




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