Re: [EnergyPlus_Support] Airflow Network Modelling

[Lixing Gu <gu@xxxxxxxxxxxx>]

Sherif:

The Airflow Network model calculates airflows driven by the pressure 
differences based on given relationships between pressure and airflow. The 
stack effect is included, but simplified. The detailed description is given 
in the section of AirflowNetwork Model in the Engineering Reference. You may 
not use the model to examine stack effect only. My suggestion is to try CFD.

My guess to get  the same amounts of volume flow rates from node 1 to 2 and 
from node 2 to 1 through the same internal opening is that the pressure 
differece across the internal opening is zero or near zero. You may try a 
different object to have one-directional flow: 
AIRFLOWNETWORK:MULTIZONE:SURFACE CRACK DATA. When the pressure difference is 
zero, the flow is also zero for this object.

Lixing

----- Original Message ----- 
From: Sherif Ezzeldin
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Sent: Monday, August 11, 2008 11:46 AM
Subject: [EnergyPlus_Support] Airflow Network Modelling


Hi,
I'm trying to simulate natural ventilation through a zone with connected two 
wind stacks.
The two stacks have openings from four directions, I scheduled the operation 
of those openings according to wind direction in order to have a supply 
stack and an extract stack for the majority of time.
Theoretically, the air enters the windward stack through its upper opening, 
moves downward towards the main zone passing through an internal opening 
connecting the stack to the zone. The heated air will be extracted by the 
extract leeward stack passing through another internal opening connecting 
the main zone with the leeward stack.
By analysing the simulation results, volume flow rates from node 1 to 2 and 
from node 2 to 1 through the same internal opening are often getting equal 
amounts at the same time which counteract the general airflow and cause 
disturbance in the general ventilation theme.
Could you please justify those results or advice me what to do in order to 
solve this problem and reach a smooth continuous one-directional flow?
Kind regards,
Sherif


 


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