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exhaust fan - input air

asked 2015-12-15 04:18:52 -0600

J Monteiro's avatar

I need to put a exhaust fan in a kitchen for the cooking hotte with the value of 5000m3/h. How openstudio model the input air of the room, it´s infiltration? it needs a supply fan?

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answered 2015-12-15 05:49:24 -0600

I'm assuming you fan to use a Fan:ZoneExhaust object. Like most E+ objects, you can usually gain a lot of valuable information by looking at the Input/Ouput reference guide of EnergyPlus. This should become a reflex.

Here is the documentation for Fan:ZoneExhaust

As stated in the introduction paragraph (emphasis is mine)

The way in which the exhaust fan impacts central air system can be controlled by declaring what portion of the flow has been balanced by simple airflow from infiltration, ventilation, or mixing. However it is important to note that presence of an exhaust fan does not by itself drive any simple airflow such as infiltration, ventilation, or zone mixing. There is no comprehensive automatic mass balancing between air system flows, exhaust flows, and the separate simple airflows. For balancing, the simple airflows need to have their own input objects that need to be coordinated with the exhaust fan.

The field Balanced Exhaust Fraction Schedule Name will be of interest to you too. By default, "it is assumed that all the exhaust air is assumed to be unbalanced by any simple airflows". What it means is that it will be reflected at the central air system (if you have one) by: - Limiting the return air going to the central handler - If the exhaust airflow is bigger than the regular return, the OA mixer will draw in even more airflow to compensate

In your case, I guess it depends where the air for the kitchen hood is coming from. If there is a a direct intake (even if just a passive duct or something), I'm not sure you should even bother to use a zone exhaust fan, but rather just a central handler. If you do want to, you'd have to make sure you create an infiltration component that matches your zonal exhaust, fan set the Balanced Exhaust Fraction Schedule Name to always 1.

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answered 2015-12-15 09:40:37 -0600

updated 2015-12-15 09:43:31 -0600

If you do have direct intake from outside, we have added ZoneVentilation:DesignFlowRate to the API and have posted a measure to add this object to BCL.

Ventilation type can set to Natural, Exhaust, Intake, or Balanced. All of these have the same airflow, but the ventilation type affects both the energy consumption and if any fan heat is added to air entering the zone.

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Asked: 2015-12-15 04:18:52 -0600

Seen: 869 times

Last updated: Dec 15 '15