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Re: [EnergyPlus_Support] How to control the outdoor air rate and total air flow rate in the HVAC system?

The values in zone sizing objects and the desing flow rates will occur when the 
system is running a full flow.  For a VAV system, this will not occur very 
often - only on the hottest days and during recovery from setback.

For VAV systems, the outside air flow rate can be proportional to the system 
flow rate (which means the outside air fraction remains constant), or a fixed 
amount (which means the outside air fraction varies).  See CONTROLLER:OUTSIDE 
AIR for more details.  But note that the VAV terminal unit min flow fractions 
must be consistent with the OA requirement.  If the total system supply air 
flow falls below the min OA requirement, the OA flow will also drop, even when 
using the fixed amount OA control.

Mike


On 9 Jan 2008 at 23:20, jpei82 wrote:

> Hi, all, now I want to simulate the energy consumption difference 
> between different ourdoor air flow rate. I specify the required OA flow 
> rate in "zone sizing" by "outside air flow per zone", but found that 
> the "zone mechanical ventilation volume flow rate" in the result does 
> not agree with the value I specified. what is the reason? 
> 
> Also , I give a fixed value in "design air flow rate" for "primary air 
> loop"  , but the volume flow rate for "mixed air node" (also VAV sys 
> inlet node, VAV sys outlet node, they have the same value), is not the 
> value I gave, but much smaller. I supposed they should be the same. Can 
> anyone tell me the reason? Thanks a lot!
> 
> 
> 
> 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.pdf under the
> Documentation link 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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Attachments are not allowed -- please post any files to the appropriate folder in the Files area of the Support Web Site.

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