[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[EnergyPlus_Support] Re: AFN Node Pressure Distribution & Air Density & STACK
Dear Lixing (or anybody else who was dealing with this before),
one more - may be a misunderstanding with the therm "thermal chimney" in the correspondence before.
1) Is it possible to use the AFN for a internal stack connecting zones in different floors, which is not utilizing solar radiation to enhance the natural ventilation - only using the inside outside temperature differences and stack hight (chimney - but no solar chimney).
2) I also read some different opinions about an atrium design with vertical zone stratification. Is that generally possible with horizontal openings (not considering entering solar radiation)? Or should here better used a single central and tall zone?
Thank you again,
Tobias
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "stray359" <steve.d.ray@...> wrote:
>
> Hi all,
>
> Does anyone know the planned future work for the AirFlowNetwork model? Are any capabilities currently being expanded for future E+ versions?
>
> From whom or where can I find out?
>
> Thanks for your help,
> Steve
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Lixing Gu <gu@> wrote:
> >
> > Tobias:
> >
> > The existing AirflowNetwork model does not address the thermal chimney yet.
> > A horizontal opening is manly used to introduce a circular flow between two
> > zones.
> >
> > Thanks.
> >
> > Lixing
> >
> > -----Original Message-----
> > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of tobiasschulzeoooitu
> > Sent: Monday, May 03, 2010 7:49 AM
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > Subject: [EnergyPlus_Support] Re: AFN Node Pressure Distribution & Air
> > Density
> >
> > Dear Lixing,
> > Thank you for your prompt answer. I have one more question about vertical
> > airflow in the AFN which for I first should describe my model a little.
> > I try to connect several floors of a high rise building to a common used
> > thermal chimney. So this stack has openings on different heights to
> > different zones. I simulated the case 1) with one chimney zone 2) multi
> > chimney zones (one per floor) connected by horizontal openings (90deg Cd=1).
> > With the one zone chimney i had a faster decrease of flow rates from bottom
> > to higher floors than with the multi zone model.
> > Anyway, my question is, if it is a meaningful way to connect more than 2
> > zones vertically by horizontal openings? What are the restictions here?
> > There is one example file available, where only two zones are stacked
> > (AirflowNetwor_Multizone_HorizontalOpening.idf). Would the model work, if
> > more zones are stacked, for example in stairways, elevator stack, atrium or
> > double skin facade? I wonder if the AFN Restriction In-Out-Ref also counts
> > for horizontal openings connections or if it was written before the
> > introduction of horiz.open. in E+.
> >
> > "Air circulation and/or air temperature stratification within thermal zone.
> > For example, you should not try to divide a high space, such as an atrium,
> > into subzones separated by artificial horizontal surfaces that have cracks
> > or openings with the expectation that AirflowNetwork will give you a
> > realistic temperature in each subzone and/or a realistic air flow between
> > subzones."
> >
> > If you would know a reference dealing with a similar problem, that would be
> > also helpful for me.
> > Best regards,
> > Tobias
> >
> >
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Lixing Gu <gu@> wrote:
> > >
> > > My answers are under your questions.
> > >
> > > 1a) Where is the Zone_Node situated Floor/ceiling/center?
> > >
> > > A: Center.
> > >
> > > 1b) Is there a link to the room-air-model (temperature at a specific
> > height
> > > - if not mixed air)?
> > >
> > > A: No.
> > >
> > > 1c) could you please give the formuala for the zone 'AirflowNetwork Node
> > > Total Pressure'? Especially how is the zone static pressure calculated?
> > >
> > > A: The model uses the total pressure, The static pressure is not
> > calculated
> > > alone. The section of AirflowNetwork model in the Engineering Reference
> > > provides detailed information.
> > >
> > > 2) For the calculation of the air density i used following formula, which
> > > wasn't found in the eng.reference - but it gives slightly different
> > results:
> > >
> > > ρ=(P_atm (1+W_air))/(461,518(T_air+273,15)(W_air+0,62198))
> > [kg/m3]
> > > ρ = Air density [kg/m3]
> > > Patm = Outdoor barometric pressure at ground level [Pa]
> > > Wair = Air humidity ratio [kgWater/kgAir]
> > > Tair = Air Temperature [°C]
> > >
> > > A: the following equation is used to calculate air density
> > > rhoair = pb/(287.d0*(tdb+KelvinConv)*(1.d0+1.6077687d0*w))
> > >
> > > Lixing
> > >
> > > ------------------------------------
> > >
> > > 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 currently allowed but be mindful that not everyone has a
> > > high speed connection. Limit attachments to small files.
> > >
> > > EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the
> > > Documentation link and press the "search" button.
> > > Yahoo! Groups Links
> > >
> >
> >
> >
> >
> > ------------------------------------
> >
> > 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 currently allowed but be mindful that not everyone has a
> > high speed connection. Limit attachments to small files.
> >
> > EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the
> > Documentation link and press the "search" button.
> > Yahoo! Groups Links
> >
>
------------------------------------
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 currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/EnergyPlus_Support/
<*> Your email settings:
Individual Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/EnergyPlus_Support/join
(Yahoo! ID required)
<*> To change settings via email:
EnergyPlus_Support-digest@xxxxxxxxxxxxxxx
EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx
<*> To unsubscribe from this group, send an email to:
EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/