Re: [EnergyPlus_Support] about the different fan model

["Michael J. Witte" <mjwitte@xxxxxxxx>]

Changing the fan object alone is not sufficient to change a VAV system to a 
constant volume system.  The air terminal units establish the upper limit on 
airflow through a system and even a constant volume fan can deliver less than 
full flow (with linear power consumption) in order to maintain mass balance.  
To do your comparison, you could use either the VAV or CV fan object and simply 
change the minimum flow fractions on the VAV terminal units to 1.0.  This will 
force the system to function as a constant volume system.

Mike


On 16 Feb 2005, at 15:04, beyangj wrote:

> 
> 
> I built a model with air-cooled chiller, and the fan model is the 
> Fan:Simple:Variable Volume, and the fan coefficient values were set 
> as the values of Inlet Vane Dampers in table 20 on page 748 in the 
> InputOutReference. The model was run and the electricity consumption 
> of the fan and the chiller was got. Then the Fan:Simple:Variable 
> Volume was substituted by the Fan:Simple:Const Volume and the model 
> was run again, and also the electricity consumption of the fan and 
> the chiller was got. I found that results of these two cases were 
> almost the same, even the result of the model with constant air 
> volume fan was a little smaller thant that of the other model.  In 
> theory, the model with variable air volume fan will consume less 
> energy than the model with constan air volume fan. I wondered why 
> that happened. Thanks in advance!
> 
> Best, 
> 
> Stewart
> 
> 
> 
> 
> 
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
> 
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
> 
> Attachments are not allowed -- please post any files to the appropriate folder
> in the Files area of the Support Web Site.
> 
> Yahoo! Groups Links
> 
> 
> 
> 
> 
> 
> 
> 
> 



========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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