Re: [EnergyPlus_Support] OA to zone calculation

[Vinay Devanathan <vinay.devanathan@xxxxxxxxx>]

Dr. Li,

 

Alright.

 

I vaguely remembered someone else askign the same or similar question regarding the variable fan on a unitary system, so I wanted to make sure I did not miss anything.

 

Thank you.

 

Vinay

On Sun, Jul 24, 2011 at 8:41 PM, YuanLu Li <yli006@xxxxxxxxxxx> wrote:

 

No detailed calculation is required.
 
Fan volume minus intake is the return air portion in the mixed air node.  The relief node volume is equal to the OA intake volume.

How the fresh air is distributed is not the function of the simulation.  It is the same fraction as in the mixed air, and does not have any different in heat properties.
 

 Dr. Li  

P.S.  I do not know why you wanted to use a variable speed  fan in the air loop.  I mention several times that a VAV fan requires a special control element to be added to the control manager object.  If you can specify the control, you can probably model it.

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To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: vinay.devanathan@xxxxxxxxx

Date: Sun, 24 Jul 2011 16:58:00 -0400
Subject: Re: [EnergyPlus_Support] OA to zone calculation

 

Dr. Li,

 

Thanks for your reply. So the OA inlet to zone is a fraction of the total OA fed in to the system right? How is that fraction calculated by E+? Is it based on a simple total airflow ratio to each zone vs. total system airflow?

 

Vinay

On Sun, Jul 24, 2011 at 1:20 PM, YuanLu Li <yli006@xxxxxxxxxxx> wrote:

 

Once the inlet air is mixed with return air, it  is just mixed air in the air loop.  The inlet OA is a fraction of the total air fed to the zones. 
 
The zone sizing is only a guide to add the OA amount.  The OA controller has the control of the air inlet amount. The OA controller is an item you add in for simulation. The inlet OA actuator may not normally be  found in a real building.
 
It is only those who wanted 100% OA supply  to the zones worry about this.
 
In a hospital, the oxygen and clean fresh air supply are piped to each bed location.

 Dr. Li  

 

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To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: vinay.devanathan@xxxxxxxxx
Date: Sat, 23 Jul 2011 23:33:32 -0400
Subject: [EnergyPlus_Support] OA to zone calculation

 

Hello,

I have been wondering about this question for a while now.

Let's say the system's OA requirements are defined by using a
Controller:OutdoorAir object. So this is the amount of minimum/maximum
OA that system brings in. But if there is no zone sizing done (all air-
side parameters hardwired), how does EnergyPlus calculate the
distribution of OA supply to different zones the system is serving?

Thank you.

Vinay

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