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

["Kristin Field" <fieldkm@xxxxxxxxx>]

Thanks for the response!  From the manufacturer and mech. schedule
data, it looks like the fans are about 46% total efficiency.  Feel
free to tell me if that doesn't sound reasonable.  To answer your
question, I'm not using the airflow network for this model.

--Kristin

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "JV Dirkes II" <jvd2pe@...>
wrote:
>
> 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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