Jean,
You can propagate a contaminant through an air flow network in EnergyPlus, but the results will not be very useful (so mixing also works). The problem is that
the contaminant will be fully mixed in the first zone as it is dispersed. If you start a fire in Zone 1, smoke rises to fill the space from the ceiling down. It doesn’t flow to the next zone until it reaches the top of a door (or some other crack in the
ceiling). In EnergyPlus the contaminant is immediately fully mixed in the space (fully diluted) and will start moving into the next zone in a diluted form where it is again further diluted by complete mixing in that zone. Generally you want to be able
to see high concentration areas when working with contaminates. CFD is better at moving the contaminant and maintaining concentrations with in a space, but many codes only have the contaminant riding on the air movement and not propagating on their own vapor
pressures. Consequently, it is difficult to properly simulate a pool of warm water in a space using most CFD because the water only moves as a contaminant on the air streams and not by vapor pressure. More sophisticated CFD that can handle phase change materials
can do better, but most of the focus in on combustion and very turbulent flow regimes, not typical of most building environments.
Ned Lyon, P.E. (MA, WV)
Staff Consultant
SIMPSON GUMPERTZ & HEGER
781.907.9000 main
781.907.9350 direct
781.907.9009 fax
www.sgh.com
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
On Behalf Of Jean marais
Sent: Tuesday, June 04, 2013 7:35 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: Contaminant Modeling
Nothing wrong with uniform gas, but the question would be how this is or can be handled across zone boundries, i.e. non-CFD, IMO. It couldn't be too hard, or?
Jean
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