[EnergyPlus_Support] Re: Mixing objects assumptions

["anarui.oliveira" <anarui.oliveira@xxxxxxxxx>]

I find the documentation isn't completely clear to me on this point.

So, if I have a zone which, in reality, has only forced exhaust, and 
which receives air by pressure difference from an adjacent zone, what 
would be the best way to model it, for the purpose of heat balance 
and thermal loads calculation?

If I use just the mixing and infiltration objects, is it actually as 
if I was continuously increasing the zone air volume? Should I add a 
mixing object to extract the correspondent airflow to some dummy zone?

If I implement an exhaust fan, since the mixing object does not use 
inlet nodes, I suppose I'll get unbalanced flow errors?...

Thanks again,
Ana.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Edwin Lee" 
<leeed2001@...> wrote:
>
> There is also a cross-mixing object, which is described in the
> documentation, that simulates air exchange between two zones, and 
therefore
> affects both zones energy balance.
> 
> On Mon, Apr 28, 2008 at 9:36 AM, Richard Raustad <RRaustad@...>
> wrote:
> 
> >   When mixing objects are used, the user is responsible for 
accurately
> > predicting the air flow into and out of a zone. Only air entering 
a zone
> > is used in the heat balance. Infiltration and mixing (into a 
zone) are
> > included in the heat balance predict step (mi and minf in Eng. 
Ref. Eq 2
> > and 5) Supply air entering a zone is included in the heat balance
> > correct step (msys in Eng. Ref. Eq 5). The return air leaving the 
zone
> > is assumed to be balanced based on the supply and exhaust node 
mass flow
> > rates (mixing and infiltration are not included here). You can 
read more
> > about the assumptions for balanced flow in the text near these 
equations
> > in the Engineering Reference.
> >
> >
> > anarui.oliveira wrote:
> > >
> > > Hi, everyone.
> > >
> > > I think I've read this somewhere, but I can't find it now:
> > >
> > > - When doing the heat Balance for a Zone Air volume that is 
receiving
> > > air with a mixing object, does E+ assume that an equal amount 
of air is
> > > withdrawn from that zone, for heat balance purposes?
> > >
> > > Thank you in advance,
> > > Ana Rui.
> > >
> > >
> >
> > --
> > Richard A. Raustad
> > Senior Research Engineer
> > Florida Solar Energy Center
> > University of Central Florida
> > 1679 Clearlake Road
> > Cocoa, FL 32922-5703
> > Phone: (321) 638-1454
> > Fax: (321) 638-1439 or 1010
> > Visit our web site at: http://www.fsec.ucf.edu
> >
> > UCF - From Promise to Prominence: Celebrating 40 Years
> >
> >  
> >
> 
> 
> [Non-text portions of this message have been removed]
>



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