Re: [EnergyPlus_Support] Oversized equipment

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

My apologies for the delayed response.

I am not sure I understand completely what you are trying to do.  When 
economizer operation is not active, the outside air flow rate is calculated as 
follows.  All names in quotes are field names for CONTROLLER:OUTSIDE AIR:

a) If "MinimumLimit"=FIXED MINIMUM, then OAFlowRate = "minimum outside air flow 
rate" * "Minimum Outside Air Schedule"

b) If "MinimumLimit"=PROPORTIONAL MINIMUM, then OAFlowRate = "minimum outside 
air flow rate" * "Minimum Outside Air Schedule" * (Current system flow 
rate/Design system flow rate) 

It sound like you need to specify a value for "minimum outside air flow rate".  
If you autosize this, the autosize value is the sum of the outside air 
requirements in the ZONE SIZING objects for zones served by this air loop.

Does this give you enough information to control the outside air flow as 
desired?

On 7 May 2006 at 4:12, eric_zhou1223 wrote:

>   Hi all,
> 
>  I was trying to simulate  an oversized equipment in a real 
> project.  A huge amount of outside air was introduced in the 
> simulation, because I must manually size both the capacity and flow 
> rate at the same time and increase them proportionally to avoid the 
> out of range error.
> 
> To keep appropriate outdoor air intake,  I have to remain the 
> autosizing value of airflow rate while only to increase the 
> autosized capacity to the real value by some way.
> 
> I noticed there is a OAFractionSched in Controller:outside Air which 
> now is all set to 1. Can I change it to a small number (such as 
> 0.01) to consider a situation where an oversized equipment is used 
> like in my case?   Is it the key to solve an oversized unit's 
> simulation?  I found modifying OAFractionSched as 0.01 didnot lead 
> to an expected result like "OA =0.01* original air flowrate" . 
> Instead,it was a much smaller value seemingly no related to the 
> original one.
>  
> Could anybody instruct me how to simulate an oversized equipment 
> like this? Thank you.
> 
> Eric
> 
> 
> 
> 
> 
> 
> 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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