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



And 3. Yes (sorry I forgot that one).

On 13 Jan 2008 at 22:36, jpei82 wrote:

> Thank you so much for your reply! Now I have some questions, :)
> 
> 1. If constant volume system is used, the OA flow and the primary 
> loop air flow rate will be constant as designed, right?
> 
> 2.if I still use VAV system, but change the VAV terminal unit min 
> flow fraction to 1, and set the primary loop flow rate, then the sum 
> of zone flow rate will be the primary loop flow rate, am I correct?
> 3. if 2) is correct, the real OA flow will be the same as set in zone 
> sizing. is that true? 
> 
> Since I am a beginner of EnergyPlus, Thank you so much again for 
> patience!
> 
> Jingjing
> 
> 
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte" 
> <mjwitte@...> wrote:
> >
> > 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@...
> >
> 
> 
> 
> 
> 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
> 
> 
> 
> 






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