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Re: [EnergyPlus_Support] Question about Cooling Tower



Mike and Edward,

thanks a lot for your comments but, unfortunately I
cannot find out what is going on. Mike, you are right,
there was some problem with the sizing. I was trying
to autosize everything (zones, system and plants) at
the same time, and i should maybe try to autosize
first the zone, then system and then plant (am I
correct?). So for that, I set some values of the
system and the plant in order to autosize the zones,
but then I keep getting this fatal error message:

**  Fatal  ** Node MassFlowRateSetPoint = 0.0,
Node=ESTE OUTLET NODE

ESTE OUTLET NODE is an air node just at the outlet of
the air primary loop (just after the heating
coil)which consist of an outside air mixer, fan,
cooling coil and single zone reheat coil.

I have even tried to set the maximum branch flow rate
to 1.3 m3/s in the air primary loop branch object
instead of autosizing it, but it keeps giving me the
same error message.

Any suggestions?

Thank you very much.

Carmen.




--- "Michael J. Witte" <mjwitte@xxxxxxxx> escribió: 
---------------------------------
There is something wrong with the sizing inputs,
because the condenser water 
pump flow rate is being sized to zero.  You should be
able to autosize the 
entire condenser loop and all of its components and it
will automatically match 
the chiller's condenser water flow rate.  See p. 317
(pdf p. 345) of the Input 
Output reference, Item 4. 

Mike


On 15 Jun 2004, at 18:20, carmen herrero prada wrote:

> Hello all,
> 
> I am having some problems while simulating condenser
> loop water cooled with a cooling tower. I am
> autosizing everything (plant sizing), except the
> Design Water Flow rate (m3/s) which has to be the
same
> that appears in the chiller object, in the field:
> Design Condenser Volumetric Flow rate (m3/s)
> 
> But, althouth I have tried with different options
(as
> creating a schedule for a Condenser Temperature
> Setpoint node in the Condenser Loop object or just
> typing AIR to use the outdoor air wet-bulb as the
> setpoint, as i have seen in the example files) I
keep
> getting the same errors:
> 
> ** Warning ** Check input. Pump nominal power or
motor
> efficiency is set to 0, for pump=CONDPUMP
>    ** Warning ** Check input. Pump nominal
volumetric
> flow rate is set or calculated = 0, for
pump=CONDPUMP
>    ** Severe  ** COOLING TOWER:SINGLE SPEED "TOWER".
> Free convection air flow rate must be less than the
> design air flow rate.
>    ** Severe  ** COOLING TOWER:SINGLE SPEED "TOWER".
> Free convection UA must be less than the design
tower
> UA.
>    **  Fatal  ** Errors found in Cooling Tower input
> 
> 
> I do not understand what is going on. I have also
> autosized the condenser pump and I have tried by
> changing the exit temperature and the delta
> temperature in the plant sizing object for the
> condenser plant.
> 
> I am sure i am missing something. Could anybody tell
> me what it is?
> 
> Thanks a lot,
> 
> Carmen.
> 
> 
> 
>
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> 
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> 
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> 
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> 
> 



========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx



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