[esp-r] VAV and Positive Air Pressure Control

[Lewis Yook]

Dear All.

This question is about VAV in control function.
Let me assume one zone to which 100 CMH air volume is supplied for heating. And the 90 CMH air volume is returned through diffuser in the same zone. 
The surplus 10 CMH air supply volume plays the role of the source of positive net pressure that prevents the air infiltration from the adjacent zones.

In this case, how should i set the the max air volume flow rate in control law? 
1) Real volume 100 CMH? or net volume 10 CMH?

2) How can I describe the supply and return separately in VAV control law?

And, I have done above simulation with the setting of  the supply air volume as net volume 10 CMH.

I found some strange results which seem to be fluctuating.
In other words, in some nodes, the flow direction changes in every time step from positive to negative and from negative to positive.
I tried to adjust the time step. However, the flow direction fluctuates between positive and negative value regardless of the time step.

3) Do you think this kind of pattern can be obtained in VAV control?

I appreciate for your interests and ideas.


Lewis Yook
Team Manager,
Integrated Simulation Team.
Design and Simulation for Sustainability (DASS) consultants Ltd.

139-743
31-dong(Business Incubator Center) 103-ho,
Seoul National University of Technology
174 Gongreung 2-dong Nowon-gu, Seoul, Korea
T. 82.2.913.2585 F. 82.2.949.2585
H. www.dasskorea.com
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