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Re: [EnergyPlus_Support] Question about Cooling Tower

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Question about Cooling Tower
From: "Michael J. Witte" <mjwitte@xxxxxxxx>
Date: Thu, 17 Jun 2004 20:50:46 -0500
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The autosizing usually works best when you autosize everything.  Go back to 
that run and look at the sizing reports in the eio output file.  Did the zones 
show a cooling load?  Did the chilled water coils size to a nonzero water flow 
rate?  Did the chiller condenser water flow rate size to a nonzero value?  Did 
the condenser loop flow rates size to a nonzero value?  If you find a zero size 
at some point along the way, then you need to check the inputs related to that 
part of the system.

Mike


On 17 Jun 2004, at 10:14, carmen herrero prada wrote:

> 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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> 
> 
> 
> ========================================================
> Michael J. Witte, GARD Analytics, Inc.
> EnergyPlus Testing and Support      
> EnergyPlus-Support@xxxxxxxx
> 
> 
> 
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References:
- Re: [EnergyPlus_Support] Question about Cooling Tower
  - From: Michael J. Witte
- Re: [EnergyPlus_Support] Question about Cooling Tower
  - From: carmen herrero prada

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