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

www.vaibhavjain.co

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:
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> Don't worry.
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> 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.
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> 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,
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> Sorry to bother you again but , regarding the air flow network, how do
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> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
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> > Subject: [EnergyPlus_Support] Actual Air flow ?
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