The method by which airflow between adjacent air nodes is
computed is by adding a TRNFlow or CONTAM (Type97) model in
parallel with your Type56 building model. You'll define airflow
paths in between your air nodes. Both of those engines, however,
are based on the assumption that the resistance to airflow between
two air nodes (i.e. through the paths that you define) is high in
comparison to the resistance to airflow of the nodes themselves.
Think of two large rooms connected by a small opening; the opening
offers much more resistance to airflow than do the rooms
themselves. Now thing of a long narrow room that is broken into
two adjacent air nodes. The airflow resistance offered by the
connection is basically the same as the air flow resistance of the
nodes themselves. Both TRNFlow and CONTAM do a better job
predicting airflow in the first case than they do in the second.
There are certainly reasons why you might want to break up a large zone into a number of adjacent airnodes, natural ventilation being one of the most common. Given that the simulation methods for estimating the mixing airflow are somewhat limited, I would only split that zone into multiple airnodes if there was a very compelling reason to do so.
kind regards,
David
Hello!
I built a large space area model, which is 8 meters long, 8 meters wide and 3 meters high. The space area is provided with four air nodes. There are no adjacent walls between the air nodes, and only two outer walls are provided in each area. Is it correct to set the area with multiple air nodes in this way? Do you need to set adjacent walls between each air node? How to determine the coupled flow between these air nodes?
Thank you very much.
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-- *************************** David BRADLEY Principal Thermal Energy Systems Specialists, LLC 3 North Pinckney Street - suite 202 Madison, WI 53703 USA P:+1.608.274.2577 d.bradley@tess-inc.com http://www.tess-inc.com http://www.trnsys.com