I am not an expert in this particular field yet of using the AFN and room air model together.
I would suggest separating the atrium volume horizontally using floors with Material:InfraredTransparent
.
You now have two or three zones each may be controlled to a different temperaure. It is not really a zone air model.
There will be no direct convection between the zones, but you may add air mixing using ducts.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: aymericnovel@xxxxxxxxx
Date: Thu, 29 Jul 2010 13:47:29 +0000
Subject: [EnergyPlus_Support] coupling zone gradient model with airflow network calculations?
Hi,
i am modelling an atrium. Obviously, I use Airflownetwork model to calculate the natural ventilation created by the height difference between the lower and higher openings.
It seems to me that the airflownetwork model assume the same temperature at both openings, right? In the engineering reference, they say the air density is assumed to be constant for pressue nodes in a zone. Actually, they describe this for a basic case of one opening with its 2 pressure nodes. But I think it also means that if a zone has two opening, just like my atrium, the density taken into account at each opening internal face is the same. Am I right?
If so, is it planned in future E+ development to allow zone gradient model calculated temperature to be used ateach opening's face? it could make a big difference regarding the calculated natural ventilation airflow...
also, if htere is indeed such a limitation right now, does anyone has come up with a good "trick" to imitate a gradient? I thought of generating this atrium by just adding holes in the intermediate floor of several piled up zones (an atrium made of several layers). that way the temperature node taken into account at the low and high level wouldn't be the same.
Now, perhaps that involves some precaution regarging the equivalence of the overall thermal balance of the atrium.
Moreover, that would pretty much screw up the pressure difference derived from heght difference right? because adding pressure differences due to everal small heigh differences is not the same as the pressure difference due to he total atrium height...
Some opinion or advises?
Thank you!
Aymeric
i am modelling an atrium. Obviously, I use Airflownetwork model to calculate the natural ventilation created by the height difference between the lower and higher openings.
It seems to me that the airflownetwork model assume the same temperature at both openings, right? In the engineering reference, they say the air density is assumed to be constant for pressue nodes in a zone. Actually, they describe this for a basic case of one opening with its 2 pressure nodes. But I think it also means that if a zone has two opening, just like my atrium, the density taken into account at each opening internal face is the same. Am I right?
If so, is it planned in future E+ development to allow zone gradient model calculated temperature to be used ateach opening's face? it could make a big difference regarding the calculated natural ventilation airflow...
also, if htere is indeed such a limitation right now, does anyone has come up with a good "trick" to imitate a gradient? I thought of generating this atrium by just adding holes in the intermediate floor of several piled up zones (an atrium made of several layers). that way the temperature node taken into account at the low and high level wouldn't be the same.
Now, perhaps that involves some precaution regarging the equivalence of the overall thermal balance of the atrium.
Moreover, that would pretty much screw up the pressure difference derived from heght difference right? because adding pressure differences due to everal small heigh differences is not the same as the pressure difference due to he total atrium height...
Some opinion or advises?
Thank you!
Aymeric
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