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Design and Settings of AirFlowNetwork model in E+ for large space served by multiple AHUs

asked 2022-05-10 03:48:43 -0500

Mariam's avatar

updated 2022-05-10 08:42:54 -0500

I am attempting to model an AirFlowNetwork in E+ as presented in my previous question: Interzone airflow between adjacent zones with open walls and dedicated AHUs, and I have some doubts I would like your help to clear out, which are:

  • What is the difference between MultizoneWithDistribution and MultizoneWithoutDistribution, which are two types of the AirflowNetwork Control that is under Class AirflowNetwork:SimulationControl? For the large space served by multiple AHUs (and I have divided this space into smaller ones with open walls (i.e., open doors) and I want to simulate the airflow network, which option should I use?

  • Can I use AirflowNetwork:MultiZone:SurfaceCrack instead of AirflowNetwork:MultiZone:Component:SimpleOpening/DetailedOpening for my vertical openings, namely the artificial doors and windows I created in the process of dividing this large space I am working on? That is, those doors and windows are not meant to ever close or be operated.

  • Any advices on setting AirflowNetwork:MultiZone:ReferenceCrackConditions?

Thank you.

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answered 2022-05-10 09:43:54 -0500

Here are some answers, happy to clarify if needed:

  • MultizoneWithoutDistribution will only use the pressure network solver to compute the airflows directly between zones and not the distribution system while MultizoneWithDistribution will compute the direct movement and the movement through ducts etc. of the distribution system. MultizoneWithDistribution requires a great deal more input, so unless you're interested in the computing the duct flows rather than just taking what E+ gives you, I'd advise MultizoneWithoutDistribution (at least to start with).

  • Yes, you can do that. You should use whatever element you can that best matches your need. We don't have an explicit object that is formulated as an orifice with a discharge coefficient, but the crack object can reinterpreted into something pretty close to the orifice equation here (it may be off by a factor of the square root of density, but that's not a huge deal).

  • You should really only use the reference conditions object if you have measurements of crack properties under non-standard conditions. In this case, the default that gets used (E+ will assume standard conditions if you don't include a reference conditions object) is likely to be good enough.

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Thank you for your reply and help. This is very useful!

Mariam's avatar Mariam  ( 2022-05-11 04:58:39 -0500 )edit

@Mariam always happy to help!

Jason DeGraw's avatar Jason DeGraw  ( 2022-05-11 08:23:32 -0500 )edit

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Asked: 2022-05-10 03:48:43 -0500

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Last updated: May 11 '22