[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: [EnergyPlus_Support] Re: Actual Air flow ?





Dear Vaibhav,

Sorry for my ignorance of the details in the I/O manual.

 

What you are indicating is that the originating zone is 1 and the adjacent zone is 2.  1 is the zone which the surfaceis defined, and w is the other side.   The interior and exterior may not be a factor in the naming.

 

When you have the full AFN diagram with the 5 external OA zones, how are the variable named?

 

A corner zone would have flow in four directions or more.  For each direction there will be 1 to 2, and 2 to 1.
 
Therefore, I was suggesting that your diagram was too simple.  If you have four cracks in one zone, I am not sure whether  flow direction 1 to 2 and 2 to 1 would have signs to indicated the actual flow.  I have not read the I/O manual yet. 
 
There may not be two flows together through one crack, and the sign for flow direction  is not easy to use.  Therefore, 1 to 2 and 2 to 1 is used to indicate the flow direction.  1 to 2 is out of the zone and 2 to 1 is into the zone.  A crack is always between two zones (OD is also a zone). If you define the wall for Zone A, and the other (Zone B) is the other side or external, zone A is node 1.  If the crack is defined in Zone B, Zone B is node 1.
 
 
 Dr. Li  

 


To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: vaibhav.energyarchitect@xxxxxxxxx
Date: Tue, 10 Jul 2012 21:19:10 +0200
Subject: Re: [EnergyPlus_Support] Re: Actual Air flow ?

 
Dear Dr.Li, 

The diagram is a graphical translation/representation of output variable: AirflowNetwork Mass Flow Rate from Node 1 to 2 (or node 2 to 1) as per I/O manual page no. 747, which is copied below. I used it to explain my colleagues in a simple/quick way about what this output variable means, hence shared here for others to see. 

AirflowNetwork Mass Flow Rate from Node 1 to 2 [kg/s] 
This is the AirflowNetwork linkage mass flow rate output in kg/s in the direction from Node 1 
to  Node  2.  It  reports  surface  airflows  through  a  crack  or  opening,  and  through  linkages 
defined in an AirflowNetwork:Distribution:Linkage object. The surface linkage is divided into 
two  types  of  surfaces,  exterior  surface  and  interior  surface.  Node  1  for  an  exterior  surface 
linkage is a thermal zone and Node 2 is an external node. The value of AirflowNetwork Mass 
Flow Rate from Node 1 to 2 represents the flow rate from a thermal zone to outdoors. The 
flow  direction  through  an  interior  surface  crack  or  opening  is  defined  from  a  thermal  zone 
defined  by  a  surface?s  Zone  Name  (Node  1)  to  an  adjacent  thermal  zone  defined  by  a 
surface?s  OutsideFaceEnvironment  (Node  2).  For  an  AirflowNetwork:Distribution:Linkage 
object, the value represents the air mass flow rate flowing from Node 1 to Node 2. 

Vaibhav Jain




On 10 July 2012 20:25, Lixing Gu <gu@xxxxxxxxxxxx> wrote:
 

I would like to clarify what Lisa said in the last paragraph.

All incoming airflows are a part of zone loads, including infiltration,
ventilation and mixing. All outgoing airflows are not a part of zone loads.

Lixing



-----Original Message-----
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of lisacng
Sent: Tuesday, July 03, 2012 9:36 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: Actual Air flow ?

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 ?
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> 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 ?
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> > Dear Forum,
>
> >
>
> >
>
> >
>
> > I modeling a room with the AirFlowNetwork object. I would like to
>
> >
>
> > confirm the following:
>
> >
>
> >
>
> >
>
> > 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?
>
> >
>
> >
>
> >
>
> > Regards,
>
> >
>
> >
>
> >
>
> > Alberto Hernandez Neto
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>

------------------------------------


Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to
energyplus-support@xxxxxxxx

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






__._,_.___


Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx

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.




Your email settings: Individual Email|Traditional
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe

__,_._,___