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[EnergyPlus_Support] Re: Circulation-only Fans: Zone Equipment?



Dear Kristin,

If you model the fans as unit heaters (which seems like a reasonable
choice to me), make sure that you've got the fan efficiency properly
defined so that the KW calculated by the Fan object is appropriate.  I
don't know typical efficiency for the circulation fans you're
modeling, but it can be derived from the air flow rate, delta Pressure
and motor data.

Although not very familiar with the EPlus algorithms, I wonder if it
even "cares" about airflow from fans in any of its convection
calculations; there's not enough information provided in the IDF
objects such as Unit Heaters, to describe airflow patterns....  Maybe
you're using Airflow Network for that (which I'm unfamiliar with)

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Kristin Field"
<fieldkm@...> wrote:
>
> Hi, I'm trying to model a set of greenhouses that are heated only with
> fin tube radiators.  The only "cooling" is through natural ventilation
> and intake fans, which I have modeled using AirFlow objects.  I don't
> have a question about this part of the model, just providing this
> info. as background.
> 
> The question I have is about modeling the circulation fans that run
> continuously in the greenhouse.  I thought of doing them as zone
> equipment, but the I/O Reference lists the types of zone equipment
> allowed, and plain "fans" are not among them.  Another option I
> considered is modeling them as unit heaters with the heating cool
> never enabled, but I was hoping for an easier solution.  The cfm is
> high and, I would think, will have a big effect of the convection part
> of the heat balance.  Without the effect on convection, I would
> otherwise just input the fan heat as an electric internal gain.
> 
> Any thoughts?
> 
> Thanks,
> Kristin Field
>




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