Re: [EnergyPlus_Support] Supply air temperature control

["Michael J. Witte" <mjwitte@xxxxxxxx>]

First, check the controller on your cooling coil.  Are the nodes correct?  Is 
the controller reverse action?  Next, try using the detailed cooling coil (it 
is autosizable in version 1.1.1).  If that does not help, please upload your 
idf file to the yahoo problem files area or send zipped to energyplus-
support@xxxxxxxx  

Mike


On 15 Jan 2004, at 9:50, Michael J Mccarty wrote:

> Hi
> I am having problems with my program not keeping the supply air temperature at
> the appropriate setpoint.  I have used purchase chilled water and have more than
> enough capacity.  My cooling coil has water supplied at 3°C and  a delta T of
> 9°C.  The supply air temperature is set at 12°C.  The trend I have been seeing
> is that when the cooling coil has the maximum flow rate of water through it, it
> can not meet the supply air setpoint.  However, when the max flow rate is
> present, the temperature rise of the water is only 1-2°C.  When the setpoint is
> actually met, the flow rate through the coil is usually small and the
> temperature rise of the water is often large.  Many times the temperature rise
> is about 12-15°C which is more than the design value of 9°C.  Also, there seems
> to be a large gap in flow rates between the maximum and the flow rates at the
> times where the setpoint temperature is met.  My cooling coil UA is about 2000
> W/delK which has been on autosize.  I have tried to increase the UA manually and
> this has not solved the problem.  I have also adjusted the chilled water
> capacity with no luck.  The delta T of the cooling water has also been adjusted.
>  Any suggestions of what might be happening?
> 
> Mike McCarty
> Graduate Student, Mechanical Engineering
> Iowa State University
> 2043 Black Engineering
> Ames, IA 50010
> 515-294-3080
> mmccarty@xxxxxxxxxxx 
> 
> 
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx


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 are of the Support Web Site.




 -- please post any files to the appropriate folder in the Files are of the Support Web Site.




 

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