Re: [EnergyPlus_Support] Re: Actual Air flow ?

Vaibhav Jain

www.vaibhavjain.co

On 5 July 2012 15:10, lisacng <lisa.ng@xxxxxxxx> wrote:

Vaibhav,

How do I see the attached picture? Is there a link?

Thanks!

Lisa

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Vaibhav Jain <vaibhav.energyarchitect@...> wrote:
>
> I have this picture (attached) I made for myself to remember the
> terminology. Might save us time, because: a picture = many words :)
>
> Vaibhav Jain
> www.vaibhavjain.co
>
>
>
>
> On 3 July 2012 15:54, Jean marais <jeannieboef@...> wrote:
>
> > **

> >
> >
> > Bidirectional flow is also calculated depending on what object you are
> > using (AirflowNetwork models such two-directional flow, but only for
> > vertical openings).
> >
> > I think you may be right that only infiltration is considered in load
> > calcs, but then exfiltration is usually less interesting (has very small
> > impact on building energy usage). This is the case for TrnSys.
> >
> > However,
> > the io ref states that exfiltration is better handled with an exhaust
> > componant and that AFN can "16) Determine the impact of zone exhaust fans
> > on air flows, pressures, air temperatures/humidity levels and energy
> > consumption."
> >
> > I've not checked the engineering ref on this.
> >
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "lisacng" <lisa.ng@> wrote:
> > >
> > > Alberto, Oscar
> > >
> > > Just to make things clear, "inside" and "outside" aren't inside the
> > building and outside the building. It is the inside or outside face of the
> > referenced surface (AirflowNetwork:MultiZone:Surface // Surface name //
> > Leakage component name) where your leakage element is.
> > >
> > > Also, in the same hour, you are seeing two different values for 1-->2
> > and 2-->1 in the same window because your time step is smaller than an
> > hour. If you output detailed or timestep results, you will see that only
> > one flow should have a value and the other is zero. The hourly output is an
> > average of the timestep outputs. If using the hourly results is fine, then
> > the flow of air is the difference of 1-->2 and 2-->1 and the direction is
> > determined by which is greater.
> > >
> > > It should be noted that EnergyPlus only uses the flow into a building
> > from the outdoors to affect the load on a zone. Exfiltration (air leaving a
> > building) and mixing of air between zones does not affect load
> > calculations. Someone out there can correct me if I'm wrong.
> > >
> > > Lisa Ng
> > > NIST
> > > IAQ & Ventilation Group
> > >
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, oscar hernandez
> > <oscarhernandez_81@> wrote:
> > > >
> > > >
> > > > Don't worry.
> > > >
> > > > If I remember, 1 to 2 is from outside to inside and 2 to 1 inside to
> > outside. Look at the energyplus input output manual (airflow network) you
> > have everything about that.
> > > >
> > > > Let me know if you need more help.
> > > >
> > > > Oscar.
> > > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > > From: ahneto@
> > > > Date: Sat, 30 Jun 2012 17:44:40 -0300
> > > > Subject: RE: [EnergyPlus_Support] Actual Air flow ?
> > > >
> > > >
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> > > > Dear Oscar,
> > > >
> > > >
> > > >
> > > > Sorry to bother you again but , regarding the air flow network, how do
> > > >
> > > > I know the direction (from inside to outside and vice versa) of the
> > > >
> > > > flow in the window?
> > > >
> > > >
> > > >
> > > > Thanks for your help.
> > > >
> > > >
> > > >
> > > > Alberto
> > > >
> > > >
> > > >
> > > > Citando oscar hernandez <oscarhernandez_81@>:
> >
> > > >
> > > >
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > > THe value 1 to 2 or 2 to 1 is the flow rate. You have to inside or
> > > >
> > > > > to outside.
> > > >
> > > > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > >
> > > > > From: ahneto@
> > > >
> > > > > Date: Fri, 29 Jun 2012 13:54:19 -0300
> > > >
> > > > > Subject: [EnergyPlus_Support] Actual Air flow ?
> > > >
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> > > > > Dear Forum,
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > > I modeling a room with the AirFlowNetwork object. I would like to
> > > >
> > > > >
> > > >
> > > > > confirm the following:
> > > >
> > > > >
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> > > > > When I set as output variable AirflowNetwork Mass Flow Rate from Node
> > > >
> > > > >
> > > >
> > > > > 1 to 2 and AirflowNetwork Mass Flow Rate from Node 2 to 1 for a
> > > >
> > > > >
> > > >
> > > > > exterior window, the difference between these two variables will give
> > > >
> > > > >
> > > >
> > > > > the actual flow rate and the direction will be set verifiying which
> > > >
> > > > >
> > > >
> > > > > variable is greater?
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> > > > > Regards,
> > > >
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> > > > > Alberto Hernandez Neto
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