Re: [EnergyPlus_Support] Supply fan and Return Fan Air Flow Rate

[Zhen Tian <tianzhen9@xxxxxxxxx>]

Thank you very much for your response, Mike.
   
  I guess the zone exhuast fan is the constant air flow fan module, right?
   
  If both supply and return fans are variable air flow fans, then the zone exhaust fan cannot be used. Can I use fan: simple:variable volume as the relief fans with delta presssure as zero?
   
  Thanks again.
   
  Regards,
   
  Zhen
   
  
"Michael J. Witte" <mjwitte@xxxxxxxx> wrote:
          EnergyPlus currently requires that all flow rates in an air loop be balanced. 
To model a system like this, you must specify zone exhaust fans which remove 
10% of the flow directly from the zones. Set the ZONE EXHAUST FAN delta 
pressure to zero so that it does not consume additional electric power.

Mike

On 3 Nov 2006 at 11:43, Zhen Tian wrote:

> Dear All,
> 
> I experienced a problem when I modelled supply constant volume fan and
> return fan in the same air system. The air system uses 100% outdoor air flow
> with heat recovery. The supply fan air flow rate is 0.62m3/s. When I did not
> add the return fan, the system node check shows the system air flow rate is
> 0.62m3/s. To represnt the real situation, a return fan was added to the air
> system with the fan air flow rate of 0.56m3/s (90% of supply flow rate so that
> room has 10% positive pressure). However, I found that the system supply air
> flow rate was also reduced to 0.56m3/s. When I change the return fan airflow
> rate, the system supply air flow rate always keeps the same as the return fan
> airflow rate.
> 
> In my air system, the component configuration sequencey is "return
> fan-cooling coil-heating coil-supply fan". The heat recovery unit is also in
> the air system but not listed in the air system branch. Could somebody help
> me out of this problem? I have no ideal what is wrong with the configuration.
> I cannot find an example that includes both return fan and heat recovery unit
> in the air system.
> 
> Thanks a lot for your help in advance.
> 
> Regards,
> 
> Zhen
> 
> 
> 
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support 
EnergyPlus-Support@xxxxxxxx



         

 
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