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Re: [EnergyPlus_Support] Purchased Air variables
2) Sorry, wrong equation - Q=M*dH
Richard Raustad wrote:
>
> 1) - the maximum reported heating/cooling rate increases
> The load met by purchased air should not change IF the zone conditions
> have not changed. Mass flow rate should increase. Check the zone
> conditions.
> PAOutput = M*Cp*dT
> 2) - Why, for instance, when cooling, the cooling rate/energy increases
> greatly when lowering the supply humidity ratio in Purchased Air
> definitions?
> Since you specified a lower humidity ratio, the dH from zone supply
> inlet to zone is greater. Q=M*Cp*dH. Mass flow rate should be the same.
> 3) - what should be the approach to choosing the supply temperature and
> humidity ratio to be set in Purchased Air objects?
> Choose the SA temp/humrat inputs to closely resemble the supply air
> conditions of the "real" system you expect to use to replace PA.
>
> anarui.oliveira wrote:
> >
> > Hello.
> > I've been doing some experimenting with Purchased Air and I'd
> > appreciate some help to better understand why:
> >
> > - the maximum reported heating/cooling rate increases as I set the
> > supply air temperatures in Purchased Air to be closer to the zone
> > setpoint temperatures?
> >
> > - Why, for instance, when cooling, the cooling rate/energy increases
> > greatly when lowering the supply humidity ratio in Purchased Air
> > definitions? Does PA actually accounts for the energy necessary to
> > force the supply airflow below dew point and then back to the
> > defined supply temperature again? I was under the ideia that PA was
> > much simpler than that?... In the affirmative case, which are the
> > departure conditions that PA considers to calculate those extra
> > energy consumptions due to HR adjustments?
> >
> > Considering that I'm using PA for a first approach of thermal load
> > estimates and equipment sizing, what should should be the approach
> > to choosing the supply temperature and humidity ratio to be set in
> > Purchased Air objects (especially HR greatly influences results)?
> >
> > Regards,
> > Ana Rui Oliveira.
> >
> >
>
> --
> 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 <http://www.fsec.ucf.edu>
>
> UCF - From Promise to Prominence: Celebrating 40 Years
>
>
--
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
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