RE: [EnergyPlus_Support] Airflow Network: Difference between Flow rate and Infiltration Volume

[Lixing Gu <gu@xxxxxxxxxxxx>]

Farhang:

The mass flow rate is used in the program. The output of Volume Flow Rate is
calculated by the mass flow rate divided by the air density as a function of
outdoor conditions.

The output of Zone Infiltration Volume is calculated by the mass flow rate
divided by air density as a function of indoor conditions. 

Therefore, you may get close results and will not get the same results due
to air density differences. In addition, air specific heat and other factors
are also involved, but may not be discussed in detail here.

Hope this helps.

Lixing   

-----Original Message-----
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Farhang
Sent: Wednesday, June 08, 2011 5:55 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Airflow Network: Difference between Flow rate
and Infiltration Volume

Hi,

I created a simple one-zone model with two windows to better understand the
Airflow
Network Outputs, and I got the following results in an specific hour:

1st_WIN:AirflowNetwork Volume Flow Rate from Node 1 to 2 [m3/s]: 0.39
1st_WIN:AirflowNetwork Volume Flow Rate from Node 2 to 1 [m3/s]: 0.00
 
2nd_WIN:AirflowNetwork Volume Flow Rate from Node 1 to 2 [m3/s]: 0.00
2nd_WIN:AirflowNetwork Volume Flow Rate from Node 2 to 1 [m3/s]: 0.39

AirflowNetwork Zone Infiltration Volume [m3](Hourly): 1417.06


I believed that the Infiltration Volume is equal to (Flow rate into the zone
* 3600) so the infiltration volume = 0.39 * 3600 = 1386.12 m3. But the
output Infiltration volume is always larger than my simple manual
calculations. 

I am an architect and I am not too into the engineering base of EnergyPlus.
Can anyone tell me, why there is a difference between the "flow rate into
the zone" and "infiltration" and how EnergyPlus calculates infiltration?




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Primary EnergyPlus support is found at:
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