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Re-cooling zone air after mixing with return air

asked 2015-09-21 02:34:14 -0500

Dewan gravatar image

updated 2015-11-12 20:05:20 -0500

I am modeling a mechanical VAC system in Energyplus similar to the image below where the system mixes fixed amount of conditioned and return air and cools it down again. image description

But I am facing difficulties with the zone equipment side. So I was wondering if I am building the system correctly or not.

  • Is it possible to build the system in Energyplus as depicted in the figure above?
  • If yes, any specific components that I should use? (I have tried the AirTerminal:SingleDuct:InletSideMixer combined with ZoneHVAC:FourPipeFanCoil but I'm getting a node error at the inlet side mixing box)
  • Any other suggestion/tips in implementing this example system in energyplus are also very welcome.

Thank you

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answered 2015-09-21 06:33:44 -0500

updated 2015-09-21 06:36:34 -0500

It depends if your are using constant flow or variable flow with fixed proportions.

For constant flow:

I believe your application actually warrants using an AirTerminal:SingleDuct:ConstantVolume:FourPipeInduction, for which you'll set the Induction Ratio to $\frac{80\%}{20\%} = 4$. If you don't have a heating coil in your terminal unit, you might have to include one anyway and zero it out, as I believe it's required.

For help and examples:

  • This object is available in the OpenStudio Application as of 1.9.0 (release candidate right now) if you need help setting it up.
  • The example file 5ZoneFPIU.idf uses one of these.

For variable flow

Probably try to debug your error, using a VAV terminal and a ZoneHVAC unit is likely the way to go.

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Asked: 2015-09-21 02:34:14 -0500

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Last updated: Sep 21 '15